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Basic Pneumatic Circuitry by ajizai

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									                                              《气动技术》双语电子教案 吴洪明
                                              Chapter 6




           Basic Pneumatic Circuitry
                For control and automation




WUHAN UNIVERSITY OF TECHNOLOGY LOGISTICS ENG. DEPT.   武汉理工大学 物流工程系
                                              《气动技术》双语电子教案 吴洪明
                                              Chapter 6



  Contents
       Introduction                     Sequential control
       Symbols                          Sequence solution
       Circuit layout                   5/3 Valves
       Actuator control 2/2 Valve       Poppet/spool logic
       Actuator control 3/2 Valve       Balanced spool logic
       Actuator control 5/2 Valve       Feedback




Click the section to advance directly to it
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Introduction
   This module shows the         A message to pneumatic
    methods of application of      circuit designers:
    pneumatic valves and               Use proven and reliable
    components for control and          design techniques
    automation                         Produce circuits and
   The methods of pure                 documentation that are
    pneumatic sequential control        clear to read
    are confined to simple             Design for safety
    examples                           Do not try to be too
   The majority of modern              clever, the circuit will be
    systems are controlled              difficult for others to read
    electronically and is the           and maintain
    subject of electro-pneumatic
    modules
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


Symbols
   The standard for fluid power symbols is ISO 1219-1. This
    is a set of basic shapes and rules for the construction of
    fluid power symbols
   Cylinders can be drawn to show their extreme or
    intermediate positions of stroke and any length above
    their width
   Valves show all states in the one symbol. The prevailing
    state is shown with the port connections
   Other components are single state symbols
                              《气动技术》双语电子教案 吴洪明
                              Chapter 6


Symbols single acting actuators
     Single acting, sprung
      instroked
     Single acting, sprung
      outstroked
     Single acting, sprung
      instroked, magnetic
     Single acting, sprung
      outstroked, magnetic
                                   《气动技术》双语电子教案 吴洪明
                                   Chapter 6


Symbols double acting actuators
      Double acting, non-
       cushioned
      Double acting, adjustable
       cushions
      Double acting, through
       rod, adjustable cushions
      Double acting, magnetic,
       adjustable cushions
      Double acting, rodless,
       magnetic, adjustable
       cushions
                             《气动技术》双语电子教案 吴洪明
                             Chapter 6

Symbols rotary actuators
    Semi-rotary double
     acting
    Rotary motor single
     direction of rotation
    Rotary motor bi-
     directional
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


Symbols valves
                                           2
   2/2 Valve push button    12             10

    / spring                               1


   3/2 Valve push button        12
                                           2
                                            10
    / spring                           3   1

   3/2 Valve detented                     2
                                            10
    lever operated          12
                                       3   1
                                   《气动技术》双语电子教案 吴洪明
                                   Chapter 6


Symbols valves
   3/2 Valve differential    12
                                             2
                                                  10

    pressure operated                   3    1

   5/2 Valve push button           4         2
                             14                12
    / spring
                                    5       1 3

   5/3 Valve double
                                    4        2
    pressure operated
    spring centre                   5       1 3
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6


Symbols valves
   A valve function is known by a pair of numbers e.g. 3/2.
    This indicates the valve has 3 main ports and 2 states
   The valve symbol shows both of the states
   Port numbering is to CETOP RP68P and shows:
       when the valve is operated at the 12 end port 1 is connected to
        port 2
       when reset to the normal state at the 10 end port 1 is connected
        to nothing (0)
                               2
                  12               10


                          3    1
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6


Symbols valves
   A valve function is known by a pair of numbers e.g. 3/2.
    This indicates the valve has 3 main ports and 2 states
   The valve symbol shows both of the states
   Port numbering is to CETOP RP68P and shows:
       when the valve is operated at the 12 end port 1 is connected to
        port 2
       when reset to the normal state at the 10 end port 1 is connected
        to nothing (0)
                             2
                    12             10


                         3   1
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


Symbols valves
    This example is for a 5/2
     valve
    This has 5 main ports and 2
     states
                                           4     2
    When the valve is operated       14             12
     at the 14 end port 1 is
     connected to port 4 (also             5   1 3
     port 2 is connected to port 3)
    When reset to the normal
     state at the 12 end port 1 is
     connected to port 2 (also
     port 4 is connected to port 5)
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Symbols valves
    This example is for a 5/2 valve
    This has 5 main ports and 2
     states
    When the valve is operated at
                                               4     2
     the 14 end port 1 is connected       14             12
     to port 4 (also port 2 is
     connected to port 3)                      5   1 3

    When reset to the normal state
     at the 12 end port 1 is connected
     to port 2 (also port 4 is
     connected to port 5)
                     《气动技术》双语电子教案 吴洪明
                     Chapter 6


Symbols operators manual
 General manual     Lever



 Push button        Pedal



 Pull button        Treadle



 Push/pull button   Rotary knob
                             《气动技术》双语电子教案 吴洪明
                             Chapter 6


Symbols operators mechanical
Plunger           Pressure



Spring normally   Pilot pressure
as a return


Roller            Differential pressure



Uni-direction     Detent in 3 positions
or one way trip
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


Symbols 5/3 valves
    All valves types shown in the normal position


    Type 1. All ports blocked



    Type 2. Outlets to exhaust



    Type 3. Supply to outlets
                                               《气动技术》双语电子教案 吴洪明
                                               Chapter 6

Symbols function components
    Non-return valve
    Flow regulator uni-
     directional
    Flow regulator bi-directional
    Two pressure ‘AND’                                         *
    Shuttle valve ‘OR’                            ISO 1219-1   Old


    Silencer
    Quick exhaust valve with
     silencer
    Pressure to electric switch
     adjustable
         * Note:   Traditional symbol in
                   extensive use (preferred)
                                    《气动技术》双语电子教案 吴洪明
                                    Chapter 6

Symbols air line equipment
    Water separator with
     automatic drain
    Filter with manual drain
    Filter with automatic drain
    Filter with automatic drain
     and service indicator
    Lubricator
    Pressure regulator with
     gauge
    F.R.L. filter, regulator,
     lubricator simplified symbol
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Circuit layout
   The standard for circuit        Circuits should be drawn
    diagrams is ISO 1219-2           with all actuators at the
                                     top of the page in order of
   A4 format or A3 folded to        sequential operation
    A4 height for inclusion in
                                    Other components to be
    a manual with other A4           drawn in sequential order
    documentation                    from the bottom up and
   To be on several sheets if       from left to right
    necessary with line             Circuit should show the
    identification code              system with pressure
   Minimum crossing lines           applied and ready to start
   Limit valves position of
    operation by actuators
    shown by a marker with
    reference code to symbol
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6


Component identification
   The ISO suggested                 Note: the a0 valve
    component numbering                symbol is drawn in the
    system is suited for large         operated position because
    circuits and those drawn on        the actuator A is
    several pages                      instroked
   For this presentation a                                a0       a1

    simple code is used                      A

   For cylinders: A,B,C etc.
   For associated feedback
    valves: alpha-numeric code                   2                   2
    ‘a0’ for proof of instroke,       12             10   12          10

    ‘a1’ for proof of outstroke       a0 3       1        a1    3    1

   For cylinder B: b0 and b1
                                                                   《气动技术》双语电子教案 吴洪明
                                                                   Chapter 6

Example circuit
                a0      a1                          b0        b1            c0    c1
        A                             B                                 C




                                                                                   Sequence
                                                                                   Run/End
                                                                                   A+
                                                                                   B+
                                                                                   B-
                                                                                   C+
                                                                                   C-
                                                                                   A-
                                                                                   Repeat
  Run/End




   a0          a1               b1                       b0        c1        c0

  10 bar max        6 bar
                             To all inlet ports marked
                 《气动技术》双语电子教案 吴洪明
                 Chapter 6




Actuator control 2/2 valve
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6

2/2 Valve actuator control
   A pair of the most basic of
    all valve types the 2/2 can
    be used to control a single
    acting cylinder
   The normally closed
    position of the valve is
    produced by the spring            2          1
   The operated position is 12        10   12    10

    produced by the push              1          2
                                OUT         IN
    button
   One valve admits air the
    other valve exhausts it
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


2/2 Valve actuator control
    The button marked OUT is
     pushed to operate the
     valve
    Air is connected to the
     cylinder and it outstrokes
    Air cannot escape to
     atmosphere through the         12
                                         2
                                             10   12
                                                       1
                                                        10
     valve marked IN as this is
     closed                      OUT
                                         1
                                                  IN
                                                       2

    The air at atmospheric
     pressure in the front of the
     cylinder vents through the
     breather port
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


2/2 Valve actuator control
   The push button of the
    valve marked OUT is
    released and it returns to a
    normal closed position
   Air is now trapped in the
    system and provided there
    are no leaks the piston rod          2          1
                                   12     10   12    10
    will stay in the outstroked
    position                             1          2
                                   OUT         IN
   If the load increases
    beyond the force exerted
    by the air the piston rod
    will start to move in
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


2/2 Valve actuator control
   The button marked IN is
    pushed to operate the valve
   Air escapes and the piston
    rod moves to the instroked
    position
   The push button must be
    held operated until the            2               1
                                 12     10        12       10
    piston rod is fully in
                                       1               2
   Atmospheric air will be      OUT         IN
    drawn in to the front of the
    cylinder through the vent
    port
                                 《气动技术》双语电子教案 吴洪明
                                 Chapter 6


2/2 Valve actuator control
   If the button marked
    IN is released the
    piston rod will remain
    in the instroked
    position
                                 2          1
                            12    10   12    10
   Any leaks in the
                                 1          2
    installation can cause OUT         IN
    the piston rod to creep
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


2/2 Valve actuator control
   To control the speed of
    the piston rod, flow
    restrictors are placed in
    the pipes close to each of
    the valves.
   Adjustment of the
    restrictors will slow down             2              1
                                 12         10   12        10
    the flow rate thereby
    giving independent                 1              2
                                 OUT             IN
    outstroke and instroke
    speed control
                                  《气动技术》双语电子教案 吴洪明
                                  Chapter 6


2/2 Valve actuator control
   By repeated operation
    of either button
    during movement the
    piston rod can be
    moved in small steps
    for approximate
                                      2              1
    positioning             12         10   12        10

   This will only be       OUT
                                  1
                                            IN
                                                 2

    successful under slow
    speeds
                                     《气动技术》双语电子教案 吴洪明
                                     Chapter 6


2/2 Valve actuator control
   With any compressed air
    system that intentionally
    traps air, the potential
    hazard of this must be
    recognised
   Unintended release or
    application of pressure can 12       2
                                          10   12
                                                        1
                                                         10
    give rise to unexpected
    movement of the piston rod OUT   1
                                               IN
                                                    2

   A pressure indicator or
    gauge must be fitted to
    warn of the presence of
    pressure
                 《气动技术》双语电子教案 吴洪明
                 Chapter 6




Actuator control 3/2 valve
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6


3/2 valve actuator control
   A 3 port valve provides the inlet
    and exhaust path and is the
    normal choice for the control of
    a single acting cylinder
   In the normal position produced               2
                                         12        10
    by the spring, the valve is closed
                                              3   1
   In the operated position
    produced by the push button the
    valve is open
   The push button must be held
    down for as long as the cylinder
    is outstroked
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6


3/2 valve actuator control
   A 3 port valve provides the inlet
    and exhaust path and is the
    normal choice for the control of a
    single acting cylinder
   In the normal position produced
                                                2
    by the spring, the valve is closed     12       10

   In the operated position produced       3   1
    by the push button the valve is
    open
   The push button must be held
    down for as long as the cylinder is
    outstroked
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6


3/2 valve actuator control
   A 3 port valve provides the inlet
    and exhaust path and is the
    normal choice for the control of
    a single acting cylinder
   In the normal position produced
                                                  2
    by the spring, the valve is closed   12        10

   In the operated position                  3   1
    produced by the push button the
    valve is open
   The push button must be held
    down for as long as the cylinder
    is outstroked
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


3/2 valve actuator control
    To generally slow the
     cylinder speed an adjustable
     bi-directional flow regulator
     or fixed restrictor can be
     used
    The flow regulator setting
     will be a compromise as the               2
                                      12        10
     ideal outstroke speed may
                                           3   1
     not produce the desired
     results for the instroke speed
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


3/2 valve actuator control
   To control the outstroke speed
    of a single acting cylinder
    without controlling the
    instroke speed, a uni-
    directional flow regulator is
    used
   The flow into the cylinder
    closes the non return valve and   12
                                               2
                                                10
    can only pass through the
    adjustable restrictor                  3   1

   By adjusting the restrictor the
    outstroke speed of the cylinder
    can be set
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


3/2 valve actuator control
    For independent speed
     control in each direction two
     flow regulators are required
    Installed in opposite
     directions to each other
    Upper regulator controls the             2
                                     12
     outstroke speed                           10

    Lower regulator controls the         3   1

     instroking speed
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

3/2 valve actuator control
    A 3 port valve provides the
     inlet and exhaust path and is the
     normal choice for the control of
     a single acting cylinder
    In the normal position produced
     by the spring, the valve is
     closed
    In the operated position                     2
                                         12        10
     produced by the push button the
     valve is open                            3   1

    The push button must be held
     down for as long as the cylinder
     is outstroked
                 《气动技术》双语电子教案 吴洪明
                 Chapter 6




Actuator control 5/2 valve
                                        《气动技术》双语电子教案 吴洪明
                                        Chapter 6

5/2 Valve actuator control
    For a double acting cylinder the        -         +

     power and exhaust paths are
     switched simultaneously
    When the button is pushed the
     supply at port 1 is connected to
                                                 4    2
     port 4 and the outlet port 2       14                 12
     connected to exhaust port 3.
                                             5       1 3
     The cylinder moves plus
    When the button is released
     port 1 is connected to port 2
     and port 4 connected to port 5.
     Cylinder minus
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


5/2 Valve actuator control
                                           -         +
    For a double acting cylinder the
     power and exhaust paths are
     switched simultaneously
    When the button is pushed the
     supply at port 1 is connected to
                                               4    2
     port 4 and the outlet port 2         14             12
     connected to exhaust port 3. The
                                               5   1 3
     cylinder moves plus
    When the button is released port 1
     is connected to port 2 and port 4
     connected to port 5. Cylinder
     minus
                                   《气动技术》双语电子教案 吴洪明
                                   Chapter 6


5/2 Valve actuator control
                                        -         +
   Independent speed control
    of the plus and minus
    movements
   In most applications speed
                                            4    2
    is controlled by restricting   14                 12
    air out of a cylinder               5       1 3
   Full power is developed to
    drive the piston with speed
    controlled by restricting
    the back pressure
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


5/2 Valve actuator control
                                            -         +
    Independent speed control of
     the plus and minus movements
    In most applications speed is
     controlled by restricting air out
     of a cylinder                              4    2
                                           14             12
    Full power is developed to
                                                5   1 3
     drive the piston with speed
     controlled by restricting the
     back pressure
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6


5/2 Valve actuator control
   Valves with a spring return are             -         +
    mono-stable and need the
    operator to be held all the time
    that the cylinder is required in
    the plus position
                                                    4     2
   Bi-stable valves will stay in the
    position they were last set         14                 12
                                                5       1 3
   The lever valve example
    illustrated indicates a detent
    mechanism. The lever need not
    be held once the new position
    has been established
                                           《气动技术》双语电子教案 吴洪明
                                           Chapter 6

Manual control
   Remote manual control of a                        -       +
    double acting cylinder
   Valve marked + will cause
    the cylinder to outstroke or
    move plus
                                                      4       2
   Valve marked - will cause              14                     12
    the cylinder to instroke or
                                                      5   1 3
    move minus
   The 5/2 double pilot valve
    is bi-stable therefore the    12
                                                2
                                                 10           12
                                                                           2
                                                                            10
    push button valves only
                                +      3        1         -            3   1
    need to be pulsed
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6

Manual control
   Remote manual control of a                    -            +

    double acting cylinder
   Valve marked + will cause
    the cylinder to outstroke or
    move plus
                                                      4    2
   Valve marked - will cause                    14                 12
    the cylinder to instroke or                       5   1 3
    move minus
   The 5/2 double pilot valve
                                             2                           2
    is bi-stable therefore the         12         10           12         10
    push button valves only             3    1                      3    1
                                   +                       -
    need to be pulsed
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Manual control
                                                  -           +
   Remote manual control of
    a double acting cylinder
   Valve marked + will cause
    the cylinder to outstroke or
    move plus
                                                      4       2
   Valve marked - will cause                    14                12

    the cylinder to instroke or                       5   1 3
    move minus
   The 5/2 double pilot valve             2                            2
    is bi-stable therefore the   12         10                12         10

    push button valves only +         3    1              -        3    1
    need to be pulsed
                                           《气动技术》双语电子教案 吴洪明
                                           Chapter 6

Manual control
   Remote manual control of a                        -       +
    double acting cylinder
   Valve marked + will cause
    the cylinder to outstroke or
    move plus
                                                      4       2
   Valve marked - will cause              14                     12
    the cylinder to instroke or
                                                      5   1 3
    move minus
   The 5/2 double pilot valve
                                                2                               2
    is bi-stable therefore the    12             10                    12           10
    push button valves only            3        1                           3   1
                                +                         -
    need to be pulsed
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Manual control
                                                     -       +
   Remote manual control of
    a double acting cylinder
   Valve marked + will cause
    the cylinder to outstroke or
    move plus                                        4       2
   Valve marked - will cause             14                     12

    the cylinder to instroke or                      5   1 3
    move minus
   The 5/2 double pilot valve                 2                          2
    is bi-stable therefore the   12             10           12            10

    push button valves only +         3        1         -            3   1
    need to be pulsed
                                           《气动技术》双语电子教案 吴洪明
                                           Chapter 6


Semi-automatic control
                                                      -           +                a1
    Manual remote start                        A
     of a double acting
     cylinder with
     automatic return
                                                          4       2
    Cylinder identified as                14                         12

     “A”                                                  5   1 3

    Trip valve operated at
     the completion of the        12
                                                2
                                                 10               12
                                                                               2
                                                                                10
     plus stroke identified            3        1                     a1   3   1
                              +                               -
     as “a1”
                                                                       《气动技术》双语电子教案 吴洪明
                                                                       Chapter 6


  Fully-automatic control   -        +        a0           a1
                                                                   Continuous automatic
                      A
                                                                    cycling from roller
                                                                    operated trip valves
                                                                   Manual Run and End of
                                4    2
                                                                    the automatic cycling
                 14                      12                        Cylinder will come to rest
                                5   1 3                             in the instroked position
                      2
                       10
                                                                    regardless of when the
12                                                                  valve is put to End
Run/End     3         1
                      2                                2
                                                                   Tags for the roller
          12                          12
                            10                          10          feedback valves a0 and
          a0 3        1                  a1        3   1            a1 show their relative
                                                                    positions
              《气动技术》双语电子教案 吴洪明
              Chapter 6




Sequential control
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6

Circuit building blocks
                     a0   a1                  b0   b1
                 A                    B




       Run/End




    These circuits can be considered as building blocks for
     larger sequential circuits consisting of two or more
     cylinders
    Each actuator will have a power valve and two associated
     feedback valves. The first actuator to move also has
     a Run/End valve
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6

Repeat pattern sequence
   A repeat pattern sequence       The signal starting the
    is one where the order of        first movement must pass
    the movements in the first       through the Run/End
    half of the sequence is          valve
    repeated in the second          Needs only the basic
    half                             building blocks to solve
   Each actuator may have          Examples of repeat
    one Out and In stroke            pattern sequences:
    only in the sequence            A+ B+ C+ D+ A- B- C-
   There may be any                 D-
    number of actuators in          A- B+ C- A+ B- C+
    the sequence
                                    C+ A+ B- C- A- B+
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6

Repeat pattern sequence   a0   a1                b0   b1
                 A                       B




       Run/End


           b0        b1             a1           a0


   The two cylinders A and B are to perform a simple repeat
    pattern sequence as follows: A+ B+ A- B-
   Apply the rule “The signal given by the completion of
    each movement will initiate the next movement”
   In this way the roller valves can be identified and labelled
                                              《气动技术》双语电子教案 吴洪明
                                              Chapter 6

Repeat pattern sequence
                      a0   a1            b0   b1               c0   c1
           A                         B                  C




Run/End


     c0          c1             a1       a0        b1          b0



         For three cylinders A, B and C also to perform a simple
          repeat pattern sequence as follows: A+ B+ C+ A- B- C-
         Apply the rule “The signal given by the completion of
          each movement will initiate the next movement”
                                           《气动技术》双语电子教案 吴洪明
                                           Chapter 6

Non-repeat pattern sequence a0   a1                  b0   b1
                   A                       B




         Run/End


             a0        b0             a1        b1


   If the rule applied to a repeat pattern sequence is applied
    to any other sequence there will be opposed signals on
    one or more of the 5/2 valves preventing operation
   This circuit demonstrates the problem
   The sequence is A+ B+ B- A-
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Opposed signals            a0   a1                 b0   b1
                  A                       B




        Run/End


            a0        b0             a1       b1


   When the valve is set to Run, cylinder A will not move
    because the 5/2 valve has an opposed signal, it is still
    being signalled to hold position by the feedback valve b0
   If A was able to move + a similar problem will occur for
    the 5/2 valve of B once it was +
   The sequence is A+ B+ B- A-
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Mechanical solution        a0   a1                 b0   b1
                  A                       B




        Run/End


            a0        b0             a1       b1


   The problem was caused by valves b0 and a1 being
    operated at the time the new opposing instruction is given
   If these two valves were “one way trip” types and over
    tripped at the last movement of stroke, only a pulse would
    be obtained instead of a continuous signal
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6

Sequence solution methods
   The main solutions to               Shift register circuits are
    solving sequences are:               similar to cascade but use
       Cascade (pneumatic)              one logic valve for every
       Shift register (pneumatic)       step
       Electro-pneumatic               Electro-pneumatic
       PLC (Programmable                circuits use solenoid
        logic controller)                valves and electro-
   Cascade circuits provide             mechanical relays
    a standard method of                PLC. The standard
    solving any sequence. It             solution for medium to
    uses a minimum of                    complex sequential
    additional logic hardware            systems (except where
    (one logic valve per                 electrical equipment
    group of sequential steps)           cannot be used)
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6

Cascade two group
   The A+ B+ B- A- circuit         Because only one group
    is solved by the two
    group cascade method             output is available at a
   The sequence is divided          time it is not possible to
    at the point where B             have opposed signals
    immediately returns
                                    A standard 5/2 double
   The two parts are
    allocated groups l and ll        pressure operated valve
   Gp l A+ B+ / Gp ll B- A-         is the cascade valve
   Two signal supplies are            Group l        Group ll
    provided from a 5/2 valve                    4    2
    one is available only in                14         12
    group l the other is         Select l        5   1 3    Select ll
    available only in group ll
                                               《气动技术》双语电子教案 吴洪明
                                               Chapter 6

Cascade (two group)   a0        a1                      b0   b1
             A                                 B




                           b0

                                          a1
   Gp l

   Gp ll

                                                   Sequence
                                                   Gp l A+ B+ Gp ll B- A-
       Run/End



                 a0                  b1
                                               《气动技术》双语电子教案 吴洪明
                                               Chapter 6

Cascade (two group)
                      a0        a1                      b0   b1
             A                                 B




                           b0

                                          a1
   Gp l

   Gp ll

                                                   Sequence
                                                   Gp l A+ B+ Gp ll B- A-
       Run/End



                 a0                  b1
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Cascade (two group)
                 a0        a1                      b0   b1
             A                            B




                      b0

                                     a1
   Gp l

   Gp ll

                                              Sequence
                                              Gp l A+ B+ Gp ll B- A-
       Run/End



           a0                   b1
                                     《气动技术》双语电子教案 吴洪明
                                     Chapter 6

Cascade (two group)
                 a0   a1                      b0   b1
             A                       B




                 b0

                                a1
   Gp l

   Gp ll

                                         Sequence
                                         Gp l A+ B+ Gp ll B- A-
       Run/End



           a0              b1
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Cascade (two group)
                 a0        a1                      b0   b1
             A                            B




                      b0

                                     a1
   Gp l

   Gp ll

                                              Sequence
                                              Gp l A+ B+ Gp ll B- A-
       Run/End



           a0                   b1
                                               《气动技术》双语电子教案 吴洪明
                                               Chapter 6

Cascade (two group)   a0        a1                      b0   b1
             A                                 B




                           b0

                                          a1
   Gp l

   Gp ll

                                                   Sequence
                                                   Gp l A+ B+ Gp ll B- A-
       Run/End



                 a0                  b1
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6


Cascade building blocks
    A two group building
     block consists of a lever
     valve to run and end the                                            Gp l
     sequence plus the 5/2
     double pilot operated                                 4    2
                                                                         Gp ll
     cascade valve                                    14            12

    For a two group system       Run/End
                                                           5   1 3       Sel ll
     consisting of any number                   2
                                                 10
     of cylinders this building   12
                                            3   1
     block and the cylinder        Sel l
     building blocks are all
     that is required to solve
     the sequence
                                 《气动技术》双语电子教案 吴洪明
                                 Chapter 6


Cascade building blocks
   This three group                         Gp l
    building block
    establishes an     Run/End

    interconnecting
                                             Gp ll
    pattern that can
                       Sel l
    be extended to     Sel ll
    any number of
    groups                                   Gp lll

                       Sel lll
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6

Dual trip building blocks
   When a sequence has a
                                                                      Send A+
    cylinder operating twice in
    one overall sequence a dual                                        a1 in x

    trip building block may be                                         a1 in y
    required for each of the two
    feedback valves
   The supply will be from           A+ in                   A+ in
    different groups and the          Group x                 Group y
    output go to different              a1
    destinations
   Example is for feedback
    valve a1 of cylinder A when    Note: can often be rationalised to less
                                   than these three components
    A is sent + both in Group x
    and Group y
                                        《气动技术》双语电子教案 吴洪明
                                        Chapter 6

Cascade rules
   Establish the correct           Interconnect the blocks as follows:
    sequence                        The first function in each group is
                                     signalled directly by that group
   Divide the sequence in to        supply
    groups. Always start a          The last trip valve operated in
    sequence with the Run/End        each group is supplied with main
                                     supply air and selects the next
    valve selecting group l e.g.     group
    R/E | A+ B+ | B- C+ | C- A-     The remaining trip valves are
                                     supplied with air from their
   Select the cylinder building     respective groups and initiate the
    blocks                           next function
   Select the cascade building     The “run/end” valve will control
                                     the signal from the last trip valve
    block                            to be operated
   Select dual trip building
    blocks if required
               《气动技术》双语电子教案 吴洪明
               Chapter 6




Three position valves
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6

5/3 Valve
   5/3 valves have a third           The majority of
    mid position
                                       applications are
   The valve can be tri-
    stable e.g. a detented             actuator positioning
    lever operator or mono-            and safety
    stable e.g. a double air or               4   2
    double solenoid with          14                  12
    spring centre                             5 1 3

   There are three common             14     4   2   12
    configurations for the mid
    position:                                 5 1 3
       All ports blocked              14             12
                                              4   2
       Centre open exhaust
       Centre open pressure                  5 1 3
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6


5/3 Valve actuator control
    The valve illustrated has “all
     ports blocked” in the mid
     position
    Whenever the mid position is              4    2

     selected the pressure
     conditions in the cylinder will
     be frozen                         14
                                               5   1 3
                                                         12

    This can be used to stop the
     piston at part stroke in some
     positioning applications
    Flow regulators mounted close
     to the cylinder to minimise
     creep
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


5/3 Valve actuator control
   The valve illustrated has “all
    ports blocked” in the mid
    position
   Whenever the mid position is             4    2

    selected the pressure conditions
    in the cylinder will be frozen
                                        14
   This can be used to stop the             5   1 3
                                                       12

    piston at part stroke in some
    positioning applications
   Flow regulators mounted close to
    the cylinder to minimise creep
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6


5/3 Valve actuator control
    The valve illustrated has “all
     ports blocked” in the mid
     position
    Whenever the mid position is              4    2

     selected the pressure
     conditions in the cylinder will
     be frozen                         14                12
                                               5   1 3
    This can be used to stop the
     piston at part stroke in some
     positioning applications
    Flow regulators mounted
     close to the cylinder to
     minimise creep
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6

5/3 Valve actuator control
    The valve illustrated has
     “all ports blocked” in the
     mid position
    Whenever the mid position           4    2

     is selected the pressure
     conditions in the cylinder
     will be frozen              14
                                         5   1 3
                                                12

    This can be used to stop the
     piston at part stroke in
     some positioning
     applications
    Flow regulators mounted
     close to the cylinder to
     minimise creep
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6

5/3 Valve actuator control
    The valve illustrated has “all
     ports blocked” in the mid
     position
    Whenever the mid position is              4    2
     selected the pressure
     conditions in the cylinder will
     be frozen                         14                12
                                               5   1 3
    This can be used to stop the
     piston at part stroke in some
     positioning applications
    Flow regulators mounted
     close to the cylinder to
     minimise creep
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


5/3 Valve actuator control
    This version of a 5/3 valve is
     “centre open exhaust”
    The supply at port 1 is
     isolated and the cylinder has
     power exhausted when this
                                      14   4    2    12
     centre position is selected
    The version illustrated shows         5   1 3
     a mono-stable version double
     pilot operated spring centre
    The cylinder will be pre-
     exhausted when changing
     from the mid position
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


5/3 Valve actuator control
    This version of a 5/3 valve is
     “centre open pressure”
    The supply at port 1 is
     connected to both sides of the
     cylinder and the exhaust ports   14             12
                                           4    2
     isolated when this centre
     position is selected
                                           5   1 3
    Can be used to balance
     pressures in positioning
     applications
    The version illustrated is
     mono-stable, double solenoid,
     spring centre
                   《气动技术》双语电子教案 吴洪明
                   Chapter 6




Logic functions for poppet and
         spool valves
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6


Logic AND
   To obtain the output Z both                    Z
    plungers X AND Y must be                           2
                                              12        10
    operated and held                     Y
                                                   3   1
   If X only is operated the air will
    be blocked at port 1 in valve Y
   If Y only is operated there will be                2
                                              12        10
    no pressure available at port 1       X
                                                   3   1
   If either X or Y is released the
    output signal Z will be lost
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Logic AND
   To obtain the output Z both                        Z
    plungers X AND Y must be
                                                           2
    operated and held                        12             10
                                         Y
   If X only is operated the air will             3       1

    be blocked at port 1 in valve Y
   If Y only is operated there will                       2
                                                  12             10
    be no pressure available at port 1
                                         X
                                                   3       1
   If either X or Y is released the
    output signal Z will be lost
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Logic AND
   To obtain the output Z both                   Z
    plungers X AND Y must be
                                                      2
    operated and held                        12        10
                                         Y
   If X only is operated the air will            3   1

    be blocked at port 1 in valve Y
   If Y only is operated there will
                                                      2
    be no pressure available at port         12        10
                                         X
    1                                             3   1

   If either X or Y is released the
    output signal Z will be lost
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Logic AND
   To obtain the output Z both                        Z
    plungers X AND Y must be
                                                           2
    operated and held                             12             10
                                         Y
   If X only is operated the air will             3       1

    be blocked at port 1 in valve Y
   If Y only is operated there will                       2
                                             12             10
    be no pressure available at port
                                         X
    1                                              3       1

   If either X or Y is released the
    output signal Z will be lost
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Logic AND
   To obtain the output Z both                   Z
    plungers X AND Y must be
                                                      2
    operated and held                        12           10
                                         Y
   If X only is operated the air will        3       1

    be blocked at port 1 in valve Y
   If Y only is operated there will                  2
                                             12           10
    be no pressure available at port     X
    1                                         3       1

   If either X or Y is released the
    output signal Z will be lost
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


Logic AND
   To obtain the output Z both                      Z
    plungers X AND Y must be
    operated and held                           12
                                                         2
                                                               10
   If X only is operated the air      Y
                                                 3       1
    will be blocked at port 1 in
    valve Y
   If Y only is operated there will                     2
                                           12             10
    be no pressure available at port   X
    1                                            3       1

   If either X or Y is released the
    output signal Z will be lost
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


Logic AND
   To obtain the output Z both                 Z
    plungers X AND Y must be
    operated and held                      12
                                                    2
                                                     10
   If X only is operated the air      Y
                                                3   1
    will be blocked at port 1 in
    valve Y
   If Y only is operated there will                2
                                           12        10
    be no pressure available at        X
    port 1                                      3   1

   If either X or Y is released the
    output signal Z will be lost
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6


Logic AND
    This method must not be used                 Z
     as a two handed safety control                   2
                                             12        10
    It is too easy to abuse. e.g. one   Y
                                                  3   1
     of the buttons could be
     permanently fixed down and
     the system operated from the                     2
                                             12
     other button only                                 10
                                         X
                                                  3   1
    Use the purpose designed two
     handed safety control unit
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Logic OR
   Use of an ‘OR’ function
    shuttle valve                                   Z
   Source X and Y can be
    remote from each other and
    remote from the destination
    of Z                                                         2
                                                        12        10
   When X or Y is operated the                     Y
    shuttle valve seal moves                                 3   1
    across to prevent the signal Z   12
                                              2
                                               10
    from being lost through the X
                                          3   1
    exhaust of the other valve
                                   《气动技术》双语电子教案 吴洪明
                                   Chapter 6


Logic OR
   Use of an ‘OR’ function
    shuttle valve                                Z
   Source X and Y can be
    remote from each other and
    remote from the destination
    of Z                                                      2
                                                     12        10
   When X or Y is operated the                 Y
    shuttle valve seal moves                              3   1

    across to prevent the signal   12
                                            2
                                                10
    Z from being lost through X
                                        3   1
    the exhaust of the other
    valve
                                        《气动技术》双语电子教案 吴洪明
                                        Chapter 6

Logic OR
   Use of an ‘OR’ function
    shuttle valve                                 Z
   Source X and Y can be
    remote from each other and
    remote from the destination
    of Z
                                                               2
                                                      12
   When X or Y is operated the                                 10
                                                  Y
    shuttle valve seal moves                               3   1
    across to prevent the signal   12
                                            2
                                             10
    Z from being lost through X
                                        3   1
    the exhaust of the other
    valve
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6

Logic OR
   Use of an ‘OR’ function
    shuttle valve                                     Z
   Source X and Y can be
    remote from each other and
    remote from the destination
    of Z
                                                                   2
   When X or Y is operated the                           12           10
                                                      Y
    shuttle valve seal moves                                   3   1
    across to prevent the signal       12
                                                2
                                                 10
    Z from being lost through      X
    the exhaust of the other                3   1

    valve
                                              《气动技术》双语电子教案 吴洪明
                                              Chapter 6


Logic OR
   Use of an ‘OR’ function
    shuttle valve                                       Z
   Source X and Y can be
    remote from each other and
    remote from the destination
    of Z                                                             2
                                                            12        10
   When X or Y is operated the                         Y
    shuttle valve seal moves                                     3   1
                                                  2
    across to prevent the signal Z       12        10
    from being lost through the      X
                                              3   1
    exhaust of the other valve
                                        《气动技术》双语电子教案 吴洪明
                                        Chapter 6

Logic NOT
   A logic NOT applies to the state
    of the output when the operating
    signal is present (the output is
    simply an inversion of the
                                                 Z
    operating signal)
                                                     2
   The valve shown is a normally           12        10
    open type (inlet port numbered 1)   X
                                                 1   3
   When the signal X is present
    there is NOT output Z
   When X is removed output Z is
    given
                                        《气动技术》双语电子教案 吴洪明
                                        Chapter 6


Logic NOT
   A logic NOT applies to the state
    of the output when the operating
    signal is present (the output is
    simply an inversion of the                   Z
    operating signal)
                                                     2
   The valve shown is a normally           12           10
                                        X
    open type (inlet port numbered 1)            1   3
   When the signal X is present
    there is NOT output Z
   When X is removed output Z is
    given
                                        《气动技术》双语电子教案 吴洪明
                                        Chapter 6


Logic NOT
    A logic NOT applies to the state
     of the output when the operating
     signal is present (the output is
     simply an inversion of the                  Z
     operating signal)
                                                     2
                                            12
    The valve shown is a normally                    10
                                        X
     open type (inlet port numbered              1   3
     1)
    When the signal X is present
     there is NOT output Z
    When X is removed output Z is
     given
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


Logic MEMORY
   A logic MEMORY allows
    the output signal state (ON or
    OFF) to be maintained after
    the input signal has been                      Z
    removed                           X
   Any bi-stable valve is a logic        12            10
                                               3       1
    MEMORY                            Y
   With this lever detented valve,
    once the lever has been
    moved X direction or Y
    direction it can be released
    and will stay in that position
                              《气动技术》双语电子教案 吴洪明
                              Chapter 6


Logic MEMORY

    A logic MEMORY
     allows the output                     Z

     signal state (ON or      X
                                  12           10
                                                    Y
     OFF) to be                        3       1

     maintained after the
     signal that set it has
     been removed
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6

Logic MEMORY
                                                      Z

    A bi-stable double                    12             10

     pilot valve can be set                       3       1

     or reset simply by a
                                                                   2
     pulse (push and                                      12        10
                                                  Y
     release) on buttons X                                     3   1

     or Y                         12
                                            2
                                             10
                              X
                                       3    1
                                  《气动技术》双语电子教案 吴洪明
                                  Chapter 6


Logic MEMORY
                                                    Z

    A bi-stable double                        12             10

     pilot valve can be set                     3        1

     or reset simply by a
                                                                   2
     pulse (push and                                     12         10
                                                    Y
     release) on buttons X                                     3   1

     or Y                         12
                                           2
                                                    10
                              X
                                       3   1
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6


Logic MEMORY
                                                     Z

    A bi-stable double                        12             10

     pilot valve can be set                      3       1

     or reset simply by a
                                                                   2
     pulse (push and                                     12         10
                                                    Y
     release) on buttons X                                     3   1

     or Y                         12
                                           2
                                            10
                              X
                                       3   1
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


Logic MEMORY
                                                     Z

   A bi-stable double                    12             10

    pilot valve can be set                       3       1

    or reset simply by a
                                                                   2
    pulse (push and                                           12       10
                                                 Y
    release) on buttons X                                      3   1

    or Y                         12
                                           2
                                            10
                             X
                                      3    1
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6

Logic MEMORY
                                                      Z

    A bi-stable double                    12             10

     pilot valve can be set                       3       1

     or reset simply by a
                                                                   2
     pulse (push and                                      12        10
                                                  Y
     release) on buttons X                                     3   1

     or Y                         12
                                            2
                                             10
                              X
                                       3    1
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6

Logic MEMORY (latch)
   A popular memory circuit is
    the latch                                                    Z
   Will not re-make after          Y
                                              1   3

    pneumatic power failure             12         10
                                                  2
   A pulse on X operates the pilot                     12       10
    / spring valve to give output Z
                                                             3   1
   A feedback from Z runs
    through the normally open                     2
    valve Y to latch the operation      12         10
                                    X
    of Z when X is released                   3   1

   A pulse on Y breaks the latch
    and Z is exhausted
                                              《气动技术》双语电子教案 吴洪明
                                              Chapter 6


Logic MEMORY (latch)
   A popular memory circuit is
    the latch                                                          Z
   Will not re-make after           Y
                                               1   3

    pneumatic power failure              12         10
                                                   2
   A pulse on X operates the                                 12           10
    pilot / spring valve to give
                                                                   3   1
    output Z
   A feedback from Z runs                         2
    through the normally open                 12         10
                                     X
    valve Y to latch the operation             3   1
    of Z when X is released
   A pulse on Y breaks the latch
    and Z is exhausted
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6

Logic MEMORY (latch)
   A popular memory circuit is
    the latch                                                    Z
                                              1   3
   Will not re-make after          Y
                                        12         10
    pneumatic power failure                       2

   A pulse on X operates the pilot                     12           10
    / spring valve to give output Z                          3   1
   A feedback from Z runs
    through the normally open           12
                                                  2
                                                   10
    valve Y to latch the operation X
                                              3   1
    of Z when X is released
   A pulse on Y breaks the latch
    and Z is exhausted
                                             《气动技术》双语电子教案 吴洪明
                                             Chapter 6


Logic MEMORY (latch)
   A popular memory circuit is the
    latch                                                        Z
                                              1   3
   Will not re-make after          Y
                                             12         10
    pneumatic power failure                       2

   A pulse on X operates the pilot                     12       10
    / spring valve to give output Z                          3   1
   A feedback from Z runs
    through the normally open           12
                                                  2
                                                   10
    valve Y to latch the operation X
                                              3   1
    of Z when X is released
   A pulse on Y breaks the latch
    and Z is exhausted
                                              《气动技术》双语电子教案 吴洪明
                                              Chapter 6

Logic MEMORY (latch)
   A popular memory circuit is
    the latch                                                     Z
                                               1   3
   Will not re-make after           Y
                                         12         10
    pneumatic power failure                        2
   A pulse on X operates the                            12       10
    pilot / spring valve to give                              3   1
    output Z
   A feedback from Z runs                         2
                                         12         10
    through the normally open        X
    valve Y to latch the operation             3   1

    of Z when X is released
   A pulse on Y breaks the latch
    and Z is exhausted
                  《气动技术》双语电子教案 吴洪明
                  Chapter 6




Logic arrangements for fully
   balanced spool valves
                                              《气动技术》双语电子教案 吴洪明
                                              Chapter 6

Logic circuits (spool valves)
    NO / NC                           5/2 OR
    Selection / Diversion             Single pulse control
    Latch                             Air conservation
    OR, AND, NOT                      Double flow
    Single pulse maker                Counting
    Slow pressure build
    Pre-select




Click the section to advance directly to it
                                   《气动技术》双语电子教案 吴洪明
                                   Chapter 6


3/2 NO / NC
   A fully balanced valve
    allows pressure on any pot               2
    or combination of ports         12        10

   A single valve can be used           3   1
    normally open or normally
    closed
   For normally open the                    2
    supply pressure is connected    12        10

    to port 1                            3   1
   For normally closed the
    supply pressure is connected
    to port 3
                                    《气动技术》双语电子教案 吴洪明
                                    Chapter 6


3/2 NO / NC
   A fully balanced valve allows
    pressure on any pot or
                                            2
    combination of ports               12       10

   A single valve can be used          3   1
    normally open or normally
    closed
   For normally open the supply
                                            2
    pressure is connected to port      12       10
    1                                   3   1
   For normally closed the
    supply pressure is connected
    to port 3
                                    《气动技术》双语电子教案 吴洪明
                                    Chapter 6

3/2 Valve selection / diversion
    Selection of one of two
     supplies connected to           12
                                              2
                                               10
     ports 1 and 3 can be
                                          3   1
     different pressures
    Diversion of one supply
     to one of two outlets
    If it is required to exhaust         3   1

     the downstream air a 5/2        12
                                              2
                                               10

     valve is required
                                     《气动技术》双语电子教案 吴洪明
                                     Chapter 6

3/2 Valve selection / diversion
     Selection of one of two
      supplies connected to               2
                                     12       10
      ports 1 and 3 can be
      different pressures             3   1

     Diversion of one supply
      to one of two outlets
     If it is required to exhaust    3   1
      the downstream air a 5/2       12       10
                                          2
      valve is required
                                       《气动技术》双语电子教案 吴洪明
                                       Chapter 6

Latch with controls
                                                             Out
    In this version of a latch
                                                             2
     the push button valves are                     12        10
     connected to perform ‘OR’                           3   1
     and ‘NOT’ functions
    The ‘OFF’ valve must be      ON   12
                                                2
                                                 10
     placed last in the signal              3   1
     chain so that if both
     valves are operated                        2
     together the ‘OFF’           OFF 12         10

     command will dominate                  3   1
     over the ‘ON’ command
                                   《气动技术》双语电子教案 吴洪明
                                   Chapter 6


OR, AND, NOT                                  z   2
                               OR    12            10
   A single 3/2 pilot                    3       1
    operated spring return
    valve can be use for any   x          y
                                              z
    of these logic functions   AND   12
                                                  2
                                                   10

   x OR y gives output z                 3       1
                               x                  y
   x AND y gives output z
                                              z   2
                               NOT
   x gives NOT z                    12            10

                                          3       1
                               x
                                   《气动技术》双语电子教案 吴洪明
                                   Chapter 6


Single pulse maker
    Converts a prolonged
     signal x into a single                    z
     pulse z                                       2
                                      12            10
    Signal z must be removed
                                           3       1
     to allow the valve to reset
     then x can be applied
     again
    The duration of the pulse             x
     can be adjusted with the
     flow regulator
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6

Slow initial pressure build up
    Choose a 3/2 pilot spring
     valve with a relatively high
                                                  2
     operating force e.g. 3 to 4         12        10
     bar                                      3   1
    When the quick connect
     coupling is made, the output
     at port 2 is controlled at the
     rate of the flow regulator
     setting
    When the pressure is high
     enough to operate the valve
     full flow will take over
                                                 《气动技术》双语电子教案 吴洪明
                                                 Chapter 6

Pre-select
   The lever valve can pre-
    select the movement of
    the cylinder OUT or IN                                    2
                                                     12        10
   The movement will occur
    the next time the plunger                             3   1

    valve is operated                 12
                                                 2
                                                  10
   The plunger valve can be                 3   1
    released immediately and
    subsequently operated                        2
                                                  10
    and released any number      12
    of times                    OUT/IN
                                             3   1
                                pre-select
                                        《气动技术》双语电子教案 吴洪明
                                        Chapter 6


5/2 OR function
    The valve at position ‘a’ is
     reversed connected and
     supplied from the valve                 4    2
                                                       12
     conventionally connected       a   14

     at position ‘b’                         5   1 3

    The cylinder can be
                                             4    2
     controlled from either                            12
                                    b   14
     position ‘a’ ‘OR’ position
                                             5   1 3
     ‘b’
                                                《气动技术》双语电子教案 吴洪明
                                                Chapter 6

Single pulse control
   Each time the foot
    operated valve is
    pressed the cylinder
    will single stroke +                             4       2
                                                                  12
    and - alternately                           14

   First foot operation                             5   1

    the cylinder moves                      2                          2
                                 12          10              12            10
    out
                                      3     1                     3    1
   Second foot operation
    the cylinder moves in
   Third….. out and so
    on
                            12        2
                                       10

                                  3   1
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6

Air conservation
   Power stroke in the instroke
    direction only
   Differential area of the piston
    gives an outstroke force when
    the pressure is balanced
                                           4       2
   Air used to outstroke is                           12
                                      14
    equivalent to a cylinder with
                                           5   1
    only the same bore as the rod
    diameter
   Assumes the cylinder is not
    loaded on the plus stroke and
    low friction
                                    《气动技术》双语电子教案 吴洪明
                                    Chapter 6

Air conservation
    Power stroke in the instroke
     direction only
    Differential area of the
     piston gives an outstroke
     force when the pressure is
     balanced                               4       2
                                                        12
                                       14
    Air used to outstroke is
     equivalent to a cylinder           5       1

     with only the same bore as
     the rod diameter
    Assumes the cylinder is not
     loaded on the plus stroke
     and low friction
                                     《气动技术》双语电子教案 吴洪明
                                     Chapter 6


Double flow
   Where a larger 3/2 valve
    is not available
   Two flow paths in a 5/2
    valve each with a
    separate supply can be             4     2
    arranged to give double     14               12
    flow or supply separate            5 1   3
    devices
   Ensure the tube size to
    the cylinder is large
    enough to take the double
    flow
                                《气动技术》双语电子教案 吴洪明
                                Chapter 6


Double flow
   Where a larger 3/2 valve
    is not available
   Two flow paths in a 5/2
    valve each with a
    separate supply can be
                                   4    2
    arranged to give double      14         12
    flow or supply separate
                                  5 1   3
    devices
   Ensure the tube size to
    the cylinder is large
    enough to take the double
    flow
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Counting                              4
   Counting applications are best
    achieved with electro-
    mechanical or programmable        3
    electronic counters
   Pneumatic counting circuits use
    large numbers of logic valves
                                      2
    and can be slow
   The counting chain shown will
    count to 4
                                      1
   Red and blue are non-
    overlapping alternate pulses,
    purple is the reset line
                                            《气动技术》双语电子教案 吴洪明
                                            Chapter 6

Counting application                                       a0   a1
                                                   A
   The counting circuit is applied
    to count 4 strokes of a cylinder
   At rest all counting valves are
    held reset by the start valve
   Start outstrokes ‘A’
   Alternate signals from ‘a1’ and
    ‘a0’ progresses operation of the
    counting valves up the chain
   On the 4th operation of ‘a1’ the               Start

    green signal resets the start
    valve to stop the cylinder
                                       a1     a0
            《气动技术》双语电子教案 吴洪明
            Chapter 6




Feedback methods
                                      《气动技术》双语电子教案 吴洪明
                                      Chapter 6


Time delay
   A signal is restricted to
    slow the rate of pressure
    build up on a pressure                      Output
    switch (3/2 differential
    pressure operated valve)                          2
                                           12             10
   When the pressure switch
                                                3 1
    operates a strong un-
    restricted output is given
   A reservoir provides
                                  Signal
    capacitance to allow less       in
    fine and sensitive settings
    on the flow regulator
    making it easy to adjust
                                           《气动技术》双语电子教案 吴洪明
                                           Chapter 6

Time delay
                                                    -        +
   Manual remote start                                                     a1

                                                A
    of a double acting
    cylinder with a time
    delay in the                                        4    2
    outstroked position                    14                    12

    before automatic                                    5   1 3

                                                                            2
    return                                                       12              10

                                                                      3 1
                         2                  2
                12           10   12         10

                     3       1    a1   3    1
                                         《气动技术》双语电子教案 吴洪明
                                         Chapter 6

Pressure decay
   Manual remote start of a                         -        +                a1
    double acting cylinder
                                                 A
   Uses a low pressure
    operated valve connected
    normally open
                                                         4    2
   When the back pressure in            14                       12
    the front of the cylinder                            5   1 3
    falls below 0.1 bar the
    return signal is given
                                         2                             2
   Connection taken between    12            10               10          12
    the cylinder and flow            3       1                         1   3   0.1bar
    regulator
   Useful for pressing work
    pieces of variable size
                                          《气动技术》双语电子教案 吴洪明
                                          Chapter 6

Electro-pneumatic
   The majority of systems use          Circuit building block for
    electrical/electronic control         each cylinder
    due to the high degree of
                                                   a0    a1
    sophistication and flexibility
   Solenoid valves are used to                A
    control cylinders
   Feedback signals are from
    reed switches, sensors and                     4     2
    electrical limit switches             14              12

   Logic is hard wired or                         5    1 3
    programmed in to a PLC
    (programmable logic
                                     a0                 a1
    controller)
      《气动技术》双语电子教案 吴洪明
      Chapter 6




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