Eddy Current Brake Mechanism by f3j9He

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									Eddy Current Brake
   Mechanism



   December 4, 2007
Introduction
 Team members and positions
     Rodney Kremer (Team Lead)
     Aaron Noel (Systems Lead)
     Mike Martinez (Technical lead)
     James Witt (Finance Manager)
 Sponsor
   Honeywell
   Simon Waddell and Balwinder Birdi
 Faculty Advisor
   Dr. Hao Xin (EE/Physics department)
Outline
   Background of current Honeywell application
   Customer needs
   Functional requirements
   Constraints and Design effects
   Ideal Final Result
   Final Design
     Analysis
     FMEA-Disc Component
     Ideality
 Bill of Materials
 Plans For Next Semester
Background
 Honeywell’s current disconnect
  system
   Shear neck
     Not effective with variable speeds
     Irreversible
     Cannot be activated at will
 Honeywell’s new disconnect
   Needs activation system
Schematic of Shear Neck
Customer Needs
 Decelerates ball screw nut to activate
  disconnect system
 Produce required differential torque
  within given constraints and
  parameters
 Recommended use of eddy current
  brake system
Mission Statement
 Our mission is to develop, design, and test
  an innovative braking mechanism that will
  activate a mechanical disconnect system,
  applicable in a broad range of aerospace
  generators.
Functional Requirements
 Activate Disconnect
   Unscrew the ball-screw nut




 Be Resettable
 Maintenance free
Constraints
Environmental Conditions                   Functional Constraints
Temperature         -50°F to 300°F      Infinite Life

Humidity            10 – 80 percent     Cannot Deteriorate over time

Imbalance           0.005 oz.-inch      Design Envelop

Pressure Range      0.75-1 atmosphere   Diameter             5 inches

Altitude            3,000 below-        Width                1.25 inches
                    70,000 feet above
                    sea level
Operate in an oil mist Environment      No Hazardous Materials

    Operation Conditions                                 Budget
Speed Range         7,200-28,800 RPM                      $2,000
Power Source        28 Volt DC

99% Operational Readiness
Eddy Current Brake
 Produce magnetic field
 Changing of Magnetic flux induces eddy currents
 Eddy Currents produce another magnetic field opposing
  first
 Opposing magnetic fields create force that reduces
  velocity.
Eddy Current Brake Rationale
 Frictionless

 Resetable

 Light Weight

 Few moving parts

 Honeywell Recommendation
Components
 Electromagnets
   Cast Iron Core
   Conducting (Copper) Wire
   Mounting bolts
 Disc
   7075 Aluminum
   Machined from plates
FMEA - Disc component
Driving Factors for Disc Design
 Stress in Disc
   Due to Imbalance
   Due to Eddy Current Force
   Due to Rotating Disc
 Temperature of Disc
 Electrical Conductivity
 Density
Modeling Stress Due to Imbalance
Stress Due to Eddy Current Force
     Red Arrows Indicate Direction of Disc Rotation
    E vectors Indicate Direction of Eddy Current Force
Force on Disc from Eddy currents
                                            Imbalance Analysis (accounts for stress from imbalance of disc, acts radially) tensil_r (lbf/in^2)


                                  0.8



                                  0.7



                                  0.6
 Force from magnetic field (lb)




                                  0.5



                                  0.4



                                  0.3



                                  0.2



                                  0.1



                                   0
                                        1   1.2               1.4               1.6                1.8                 2                2.2      2.4
                                                                                          radius (in)
Stress Due to Rotating Disc




     Where a = inner radius
           b = outer radius
           v = Poisson’s ratio
           ρ = material density
           ω = angular velocity [rad/s]
           r = radius of interest
Heat Transfer       (assumptions)

 Disc is approximated as flat plate with
  average velocity, V
 Radiation Heat Transfer Rate is Negligible
 Disc Rotation Rate 7,200 RPM
 Thermo-physical of oil mist can be
  approximated with that of engine oil
 Neglect Heat Transfer out of outer edge of
  the disc
 Neglect Conduction through Disc/shaft
  mating surface
Eddy Current Force Analysis
 Preliminary MATLAB
  analysis

 Faraday Software
      Verification
      Optimization
        Single vs. Paired      (Images from current MATLAB simulation)
         Electromagnets
        Constant vs.
         Alternating Polarity
        Relative Proximity
        Coil Shape
        Radius
        Number of
         electromagnets/pairs
      Visualization
Test Rig
Test Rig Supports
Design Matrix
Ideal Final Result
   Predictable and Scalable Torque
   No weight
   Perfectly balanced
   No parts
   No frictional contact
   Lasts Forever
   Takes up no space
   Operates at any angular velocity
   Needs no power supply
   Maintenance Free
    Ideality
Function                                 Importance   Score Max
   1. Predictable and Scalable Torque    10           8      10
   2. No weight                          8            4      10
   3. Perfectly balanced                 7            8      10
   4. No parts                           1            2      10
   5. No frictional contact              10           10     10
   6. Lasts Forever                      5            5      10
   7. Takes up no space                  5            4      10
   8. Operates at any angular velocity   9            7      10
   9. Needs no power supply              2            1      10
   10. Maintenance Free                  9            9      10
9
     IMPORTANCE i * SCORE i     381
 IMPORTANCE * MAXSCORE 660  .577
i 1
                                        Ideality = 57.7%
              i             i
                                Bill of Materials
        Item           Source                   Specs                  Qty          Price        Total
Disc             Speedy Metals            7075-T651               1/4”x1’x1’         $49.42        +
EM Core          Speedy Metals            Cast Iron               5/8” Diameter      $3.84       $71.71
                                                                  Extruded 24”
Dewalt Motor     Sears                    24 VDC, 21000 RPM              1           $43.05      57.31
                                          nom T=94.5 in-lb
Faraday          Integrated Engineering   Calc. time dependant,   6 month license    $1,000      $1,000
                 Software                 3D Eddy Currents
DAQ Devices      AME Dept.
EM Bolts         McMaster-Carr            316 Stainless steel            8           $2.38       $27.03
Wire             WesBell Electronics      20 AWG                        500’         $17.50      $26.45
Wire             WesBell Electronics      22 AWG                        500’         $11.75      $20.70
Optical Sensor   Reliability Direct       Monarch remote                 1          $140.00     $151.00
                                          optical sensor
Test Rig Metal   Hi-Temp Metals           6061 Aluminum (+cut)     433 cubic Inch   $217.00     $230.24

Test Rig         Hardware Metal           Various Hardware                           $14.56      $14.56
Hardware         Specialties              Components
DMM              Multi-meter              DMM with Computer              1           $79.95      $84.90
                 warehouse                Output
Total                                                                               $1,579.45   $1,683.90
Plans for Next Semester
   Continue Remaining Analysis
   Build the Test Rig
   Build ECBS
   Testing and Optimization
   Develop Final Product
Questions???
                                         d
Faraday’s Law                  E  ds   dt  V
                  Faraday’s Law:
 Equations used with 
   Lenz’s Law, V  E  r ,   V  IR
 Induced Current by changing magnetic Flux
Faraday’s Law & Eddy Current
Brake Theory
 Our understanding of Eddy Current
 Relation of Faraday’s Law and Eddy
  Current brake


           Retardant Force:


                 FB
Ampere and Faraday’s Equations:
                      
             d            
   E  ds   dt &  BI  ds  0 I
                    B




Use Ampere’s Law to approximate eddy current
with a circular wire loop of radius r:
       
       E  ds  V             V  IR
                                   
                                  BI  2r
       BI  2r   0 I       I
                                       0
                                       
                  d  2               BI  2r
       E  ds   dt Br  V  IR         0
                                                  R

                     d  2R 
                     B     BI
                     dt  0r
Design Concepts
 A single electro-magnet
 Two electro-magnets of opposite
  Polarity
 Two electro-magnets on each side of
  disc
 Rotating arms of electro-magnets
Problem Statement
 Activate an existing disconnect
  system for high-speed Aerospace
  generator
   Non mechanical
   Resettable
   Activated at will (variable speeds)

								
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