Powertrain by wuyunqing


									                                           AWD grabs more traction
                                           In North America, according to a J.D.       erate AWD functionality, more FWD-
                                           Power-LMC Forecasting Service all-          based vehicles will offer AWD,” said Joe
                                           wheel-drive (AWD) report, more front-       Palazzolo, Manager of Propulsion Systems
                                           wheel-drive (FWD) vehicles will be fitted    at Wavecrest’s Vehicle Systems Group
                                           with four-wheel-drive technology by         and the Chairperson of the SAE (Society
                                           2008. In Europe, the forecast is the re-    of Automotive Engineers) All-Wheel-Drive
                                           verse, as rear-wheel-drive (RWD) vehicles   Standards Committee. “In Europe, for
                                           will grab a greater share of four-wheel-    fuel economy reasons, two-wheel-drive
                                           drive technology by 2008. In Japan and      vehicles that are RWD-based are very
                                           South Korea—the dominant Asian mar-         common. As European markets move
                                           kets for AWD technology—the penetra-        toward adopting AWD, the trend seems
                                           tion of four-wheel drive is expected to     to suggest greater growth in RWD-based
                                           decline by 2008.                            vehicles.”
                                               “In North America, AWD is a technol-        The popularity of AWD vehicles is
                                           ogy that could eventually become a stan-    abundantly evident in pickup trucks,
                                           dard feature as drivers are expecting en-   SUVs, and crossover vehicles in North
                                           hanced vehicle performance. So to prolif-   America. But other vehicle categories
                                                                                       could be a viable source for AWD func-
                                                                                       tionality. To prove that point, engineers at
                                                                                       Getrag Driveline Systems tagged a FWD
                                                                                       sub-compact car for an AWD vehicle
                                                                                       makeover. “We wanted a hard vehicle to
                                                                                       convert because we wanted to demon-
                                                                                       strate what we can do,” said Michael
                                                                                       Auweiler, Manager of Systems
                                                                                       Engineering, during the September SAE
                                                                                       International AWD Systems, Security, and
                                                                                       Driver Interaction Symposium at the
                                                                                       Dana Technical Resource Park in Ottawa
                                                                                       Lake, MI.
                                                                                           Getrag engineers recently fitted three
                                                                                       identical sub-compact cars with the sup-
                                                                                       plier’s Twinster, patent-pending AWD
                         The aluminum lid of a Haldex coupling shows the
                         location of the check valve and relief valve that have        technology that uses a modular power-
                         been added to the Generation II system to create a            takeoff unit (PTU). “The overall system is
                         pre-charge function.                                          unique in the sense that it has the elec-
                                                                                       tronically controlled couplings in the
                                                                                       front, whereas a classic AWD has one
                                                                                       coupling in the rear. One feature of the
                                                                                       PTU is that it can provide active yaw con-
                                                                                       trol at very competitive pricing,” said
                                                                                       Werner Hoffmann, Managing Director at
                                                                                       Getrag Driveline Systems, adding, “And
                                                                                       with very little hardware change, we can
                                                                                       achieve a completely different driveline
                                                                                       layout—or different torque flow in the
                                                                                       driveline—which is important for vehicle
                                                                                       branding.” Getrag’s Twinster system
                                                                                       could see production application in the
                                                                                       2008 model year.
                                                                                           The Volvo XC90 was the first vehicle
                         The Getrag Twinster patent-pending AWD technology             to feature Haldex Traction’s limited-slip
                         uses a modular power-takeoff unit.                            coupling Generation II product. The next

36 FEBRUARY 2005   aei
                                                 wheels as a result.”                             of torque is transferred prior to wheel
                                                     Generation II with pre-charge means          rotation through the use of electronic
                                                 the addition of a check valve, relief valve,     sensors and microcomputer controls de-
                                                 and a new piston-type pump. “The soft-           veloped by BorgWarner.
                                                 ware is changed to control the pump de-              “PTM is a new coupling technology
                                                 pending on the difference in actual pres-        that can be applied to north-south and
                                                 sure in the coupling and required pres-          east-west powertrains for AWD,” said
                                                 sure,” said Davidsson.                           Bruder, adding, “The PTM coupling can
                                                     Another difference between                   be activated without any movement from
                                                 Generation II and Generation II with pre-        the driveline.” The system can be mount-
                                                 charge is that Generation II “requires           ed anywhere between the transmission
                                                 about 45° of differential rotation of the        output and the secondary axle input. In
                                                 in- and outgoing shaft to create enough          addition, PTM can limit torque transfer to
                                                 pressure to transfer 2000 N·m. With pre-         the PTU and secondary axle. “PTM can be
The pre-emptive torque management device
from BorgWarner can be set to electronically     charge, 800 N·m can be transferred with-         set to electronically limit torque in the
limit torque in the driveline to enable use of   out any differential rotation at all, [and]      driveline to enable use of lighter weight
lighter weight driveline components.             2000 N·m requires 15° rotation.”                 driveline components,” said Bruder.
                                                 Davidsson declined to name the vehicle               AWD technology is continually evolv-
evolution of the torque control device is        manufacturer that will debut Generation          ing. “The goal of next-generation AWD
known as Generation II with pre-charge           II with pre-charge.                              systems is really two-fold,” said Andy
function.                                            BorgWarner engineers recently un-            Perakes, Four-Wheel-Drive/Driveline
   “In the Generation II with pre-charge,        veiled two new production-ready tech-            Technical Specialist for Ford’s Powertrain
the hydraulic system can be pre-charged          nologies for torque management: interac-         Research and Advanced Engineering. He
using the small electric feeder pump.            tive differential control (IDC) and pre-         points out that certain systems “will focus
The pump is also part of the standard            emptive torque management (PTM).                 on improving cost, quality, and fuel ef-
Generation I system, but in that case it is          IDC uses BorgWarner-developed elec-          ficiency to offer broader appeal on high-
only used to create a base pressure that         tronic controls to deliver optimal biasing       er-volume SUVs, minivans, cars, and
makes the whole system work,” said               torque across the center differential auto-      crossover vehicles, [while] advanced AWD
Per-Olof Davidsson, Application Manager          matically. “IDC combines the constant            systems—those that provide significant
for Haldex Traction Systems. “In a ve-           power delivery of a center differential          enhancements to handling and stability
hicle with Generation II with pre-charge,        with the active front-to-rear torque bias-       via torque vectoring—will focus on prov-
the system pressure can be built up inde-        ing of an on-demand system for superior          ing their worth and testing their market
pendently of the differential speed be-          traction and handling,” said Dave Bruder,        acceptance on premium-level SUVs and
tween the axles. The advantage is that           Chief Engineer at BorgWarner                     high-performance cars.”
the coupling can be locked before take-          TorqTransfer Systems. PTM delivers torque                                      Kami Buchholz
off with no initial wheel slip of the front      before a wheel slips as a precise amount

Valeo stops and starts
Hyundai announced at the Paris Auto                                                               the system does not operate during park-
Show that it had installed Valeo’s belt-                                                          ing maneuvers.
driven Start-Stop system on its ECO Getz                                                              The system combines the functions of
1.1 CRDi concept, described as a “super-                                                          a starter and an alternator into a single
low emission” vehicle. It is the first appli-                                                      unit, operating at 14-V. The electronics
cation of Valeo’s technology on a diesel                                                          and software specifically developed to
engine. Hyundai calls it ISG (Idle Stop &                                                         combine the functions have also delivered
Go). It was adapted specifically by Valeo                                                          better performance than the individual
and Hyundai for the new-generation die-                                                           components. In starter mode, the belt
sel engine to reduce noise and air pollu-                                                         drive and low inertia produce starting
tion.                                                                                             times quicker than a traditional starter. In
    After a halt in traffic or at a stop light,                                                    alternator mode, the machine outputs
the engine is restarted automatically                                                             over 15% more than a conventional al-
when the driver engages a gear or (with                                                           ternator of similar size.
an automatic gearbox) releases the brake                                                              Valeo’s Start-Stop technology will be
pedal. Fuel consumption in built-up areas,                                                        featured as an option on the production
where traffic routinely stops and starts, is                                                       2005 Citroën C3, and on a research proj-
claimed to be reduced by up to 10%. The          Valeo’s belt-driven Start-Stop system has been   ect micro-hybrid Ford Fiesta.
                                                 fitted to Hyundai’s ECO Getz diesel-engined
intelligent control strategy ensures that        concept.
                                                                                                                                  Stuart Birch

38 FEBRUARY 2005   aei
More power for Toyota’s I4 truck engine
Toyota’s new truck four-cylinder engine
made its North American debut in the
company’s Tacoma compact pickup. The
2.7-L 2TR-FE I4 engine is similar to the
company’s 2.4-L 1TR-FE engine that ar-
rived previously in the Hi Lux truck sold
everywhere else in the world.                                                                                Thinner valve stems, hollow
                                                                                                             camshafts, softer valve
    In the U.S. market, the 2.7-L 2TR-FE                                                                     springs, and low-friction roller
replaces two four-cylinder engines previ-                                                                    cam followers reduce strain
ously employed in the Tacoma, a 2.4-L                                                                        in the valvetrain, permitting
                                                                                                             a lightweight cam chain that
and a 2.7-L I4. One obvious change to
                                                                                                             produces less noise.
the new engine is the front cover, which
now incorporates direct mounting lugs
for the alternator, power steering pump,
oil pump, water pump, and thermostat.
Direct mounting reduces assembly com-
plexity and eliminates mounting brackets
as a source of NVH.                           Paul Williamsen, Product Education
    The new engine is significantly more       Manager for the University of Toyota.
powerful than the old engines, while          Output is 164 hp (122 kW) and 183 lb·ft
burning less fuel and creating less harm-     (248 N·m).
ful exhaust emissions. The improved per-          A new 32-bit engine management
formance is thanks to a raft of new tech-     computer processes data faster than the
nologies such as variable-valve timing        previous engine’s 16-bit computer, han-
that substantially modernize Toyota’s         dling input from switches and sensors
truck powerplant.                             sooner and providing quicker operation
    “With things like a plastic intake man-   of outputs such as ignition, fuel injection,
ifold and direct ignition system, you get     throttle angle, and transmission shifting.
a whole range of improvements,” said          “Putting in a dramatically more powerful
                                              computer gives you more control,”               Dual counter-rotating balance shafts reside
                                                                                              in the 2TR-FE’s iron block with a new quieter
                                              Williamsen observed.                            drive system.
                                                  The 2TR-FE’s valvetrain is probably its
                                              biggest advance. The variable-valve tim-
                                              ing system contributes to the engine’s              Similar refinements to the drive system
                                              LEV-II emissions rating along with im-          for the counter-rotating balance shafts
                                              proved driveability. “The torque curve is a     also reduce the noise from that source.
                                              lot nicer because this engine has variable      The purpose of the balance shafts is to
                                              valve timing, which the old one did not,”       cancel second-order vibration inherent in
                                              said Williamsen.                                large-displacement inline four-cylinder
                                                  While variable-valve timing attracts        engines, but the drive system can produce
                                              attention, the real advances are in the         as much noise as the shafts eliminate,
                                              details of this valvetrain, which was de-       according to Williamsen.
                                              signed for minimal reciprocating mass.              Air injection passages cast directly into
                                              Thinner valve stems reduce mass, while          the engine’s head contribute to its low
                                              roller cam followers cut friction. The re-      emissions without the complexity or po-
                                              duced mass permits softer valve springs,        tential failure of add-on air injection tubes
                                              which in turn allow lighter, hollow cam-        to the exhaust manifold. All of the ad-
                                              shafts. As a result, the cam chain is lighter   vances contribute to EPA fuel economy
                                              and smaller, so it produces less noise and      ratings of 22 mpg city and 28 mpg high-
                                              occupies less space under hood. Use of          way.
The Toyota 2TR-FE engine’s front cover        high-strength steel permits a surprisingly                                        Dan Carney
casting incorporates mounts for the           compact cam-chain system, according to
alternator, power steering pump, oil pump,
water pump, and thermostat for simplified      Williamsen. “The chain is 30% smaller
assembly and reduced noise.                   than the chain on your bicycle,” he said.

40 FEBRUARY 2005   aei
Chrysler’s next four-cylinder engine family
Electronically controlled intake flow-con-                                                                       three parties, but Hyundai had the lead
trol valves and dual variable-valve timing                                                                      design role of the base engine,” said
(VVT) are key engineering contributions                                                                         Bruce Coventry, President of the GEMA
from the Chrysler Group to a four-cylin-                                                                        joint venture. Because of economies of
der base world engine co-developed by                                                                           scale and bundled parts purchasing, the
Hyundai, Mitsubishi, and                                                                                        combined development approach will
DaimlerChrysler. Approximately two                                                                              save DaimlerChrysler an estimated $100
million engines will be produced annu-                                                                          million per year.
ally via the automakers’ Global Engine                                                                              Chrysler Group’s key contributions to
Manufacturing Alliance (GEMA) initia-                                                                           the base engine included the design of
tive.                                                  Flow control valves, located on the intake               the dual VVT and of an intake manifold
    The three automakers will employ a                 manifold in front of the intake ports, affect            with four flow-control valves. “The flow-
                                                       the charge-motion of air as it flows through
new engine variant in several vehicles.                the intake port and enters the combustion                control valves block off part of the air-
“We worked together on the program,”                   chamber.                                                 flow, and in doing so increase charge-air
said Eric Ridenour, Executive Vice                                                                              motion. In the past, we’ve accomplished
President of Product Development for the                                                                        this by the port design. But with flow-
Chrysler Group, adding, “But once we                                                                            control valves, it’s not such a compromise
get to market, we’re competitors.” The                                                                          between low- and high-speed perfor-
                                                                                                                mance,” said Gary Rogers, I4 Base Engine
                                                                                                                Manager for the Chrysler Group.
                                                                                                                Actuation of the flow-control valves is via
                                                                                                                an electric motor.
                                                                                                                    In addition to the intake charge-air
                                                                                                                motion-control valves, the new engines
                                                       A variety of select-fit components help to                will give Chrysler its first four-cylinder en-
                                                       minimize NVH on the new DaimlerChrysler                  gine with a die-cast aluminum block fea-
                                                       I4 engine.
                                                                                                                turing dual VVT. The original base world
                                                                                                                engine had intake VVT only, but the
                                                       new inline four-cylinder for Chrysler will               Chrysler Group added exhaust VVT to
                                                       be produced in displacements of 1.8, 2.0,                create dual VVT. “We’ve designed into
                                                       and 2.4 L at GEMA’s Dundee, MI, plants.                  the engine a dual variable-valvetrain sys-
                                                           For Chrysler, the new aluminum block                 tem, and that involved packaging it in the
                                                       engines—slated to replace the automak-                   engine and adapting the timing drive
                                                       er’s existing inline four-cylinder cast iron             mechanism as well as the calibration of
                                                       block engines—will improve engine fuel                   the final product,” said Rogers.
                                                       economy by 5%. In addition, the engines                      CAE tools, including Pro/Mechanica
                                                       will meet the ultra-clean ULEV II emissions              from PTC, Excite from AVL, MSC.Nastran
The new aluminum-block 2.4-L engine will               standards.                                               from MSC.Software, ABAQUS from
account for approximately two-thirds of
the inline four-cylinder production for the                “The base engine design did have a                   Abaqus, Valdyn from Ricardo, MATLAB/
Chrysler Group.                                        tremendous amount of input from all                      Simulink from The MathWorks,
                                                                                                                Flowmaster from Flowmaster, and
                                                                                                                FEMFAT from Magna Steyr, as well as
                 Preliminary DaimlerChrysler GEMA Engine Specifications                                          proprietary in-house tools, enabled
Displacement             2.4 L                         2.0 L                       1.8 L                        Chrysler Group engineers to finesse the
Estimated power          170 hp (127 kW)               150 hp (112 kW)             140 hp (104 kW)              NVH characteristics. For instance, the en-
Estimated torque         165 lb·ft (224 N·m)           140 lb·ft (190 N·m)         125 lb·ft (169 N·m)          gines will use select-fit pistons, bearings,
Bore x stroke            88 x 97 mm (3.5 x 3.8 in) 86 x 86 mm (3.4 x 3.4 in) 86 x 77.4 mm (3.4 x 3.0 in)        and tappets, as well as a damped oilpan
Valve system             Dual overhead camshaft, dual variable-valve timing, direct-acting shimless
                                                                                                                made of metal/composite/metal, and an
                         mechanical bucket tappet
                                                                                                                isolated valve cover that is separated from
Fuel injection           Sequential, multi-port, electronic, returnless
                                                                                                                the cylinder head via an elastomeric seal
Type                     Inline four-cylinder aluminum block
                                                                                                                and isolated fastener grommets. “That’s
Construction             High-pressure, die-cast aluminum block with cast-in-place iron liners, cast aluminum
                         ladder frame, aluminum cylinder heads                                                  another one of the things that we devel-
Compression ratio        10.5:1                                                                                 oped on our side of the equation,” said
Maximum engine speed     6750 rpm                                                                               Ridenour.
Fuel requirement         Unleaded, regular, 87 octane (R+M)/2 recommended                                           The world engine’s use of select-fit
Oil capacity             4.5 qt (4.3 L)                                                                         components also includes mechanical
                                                                                                                bucket tappets in the valvetrain. Current

                                                                                                                                         aei   FEBRUARY 2005 41
DOHC four-cylinder Chrysler Group en-          ers. “For an all-new engine, that’s the         Dundee, MI. Each of the two 450,000 ft2
gines use a roller finger follower valve-       most we’ve ever done—usually it’s about         (41,800 m2) Michigan plants will have
train with hydraulic lash elements, while      one-third of that,” said Don Goodwin,           capacity of 420,000 units a year. The first
SOHC engines use a roller rocker arm           Vice President of Scientific Laboratories        Dundee plant launches full production in
with hydraulic lash elements.                  and Proving Grounds for the Chrysler            September 2005 with the second plant
    More than 15 million customer-equiv-       Group.                                          launching full production in September
alent miles were accomplished during              Engines will be produced in Asan and         2006.
durability testing by the three automak-       Hwasung, South Korea; Shiga, Japan; and                                     Kami Buchholz

Nothing sad about ISAD
Hybrid versions of the 2005 Chevrolet          voltage directly from the battery.              storage, and subsequent conversion into
Silverado and GMC Sierra full-size pickup          ”Through a CAN interface, the control       propulsive power would therefore be less
trucks feature Continental’s integrated        electronics continually exchange informa-       than 20%. In contrast, the 42-V ISAD
starter-alternator damper (ISAD) as a way      tion about the current vehicle condition        system combined with the ultracapacitor
to improve the vehicle’s fuel economy by       with the other control devices of the ve-       storage unit can reach a total efficiency
up to 13%. The ISAD system replaces the        hicle. [The ISAD] can therefore adjust to       as high as 80%, making energy recovery
conventional starter, alternator, and fly-      the most favorable operating point of the       a viable proposition.”
wheel with an electronically controlled        starter-generator system at any time,”              After more than six years of research
unit that uses thin, flat copper sheets to      said Tom Herrington, ISAD’s Key Account         and development time, the ISAD technol-
fill the slots unlike a conventional winding    Manager at Continental Automotive               ogy’s primary challenge was the task of
motor. High-power control electronics          Systems.                                        making it part of an existing vehicle. “As
generate the ISAD system’s operating               One advantage associated with the           this system had to be background-com-
                                               ISAD’s control electronics relates to the       patible with the existing drivetrain—
                                               packaging needs. “Because of the sophis-        meaning a bolt-on system—the biggest
                                               ticated cooling system, the electronic          challenges for ISAD were working around
                                               components can be arranged three-di-            the current inputs and outputs, and inte-
                                               mensionally, thus making best use of            grating them into the ISAD technology to
                                               available space,” said Herrington, adding       satisfy the vehicle and customer-specific
                                               that the electronics can be built to mount      expectations,” said Herrington.
                                               directly on the electric motor without a            The final design consists of a 42-V
                                               connector cable. “Since no connectors           island configuration that is compatible
                                               are necessary between the electronic sys-       with today’s 12-V onboard networks. As
                                               tem and the motor, there is a significant        an option, ISAD can generate power for
                                               reduction in cost, weight, and power            110- or 220-V ac equipment, such as
                                               losses,” said Herrington.                       power tools commonly used at a con-
                                                   The ISAD technology is associated           struction site. “The 120-V ac power out-
                                               with regenerative braking. “Energy recov-       let testing was the most unique test done
                                               ery is uneconomical with conventional           during the development. We tested nu-
                                               systems since efficiencies today are only a      merous 120-V ac appliances, tools, etc. to
                                               maximum 50% for belt-driven 12-V alter-         ensure the correct functionality and safe-
                                               nators and motors, and 70% for lead-            ty,” said Herrington.
Continental’s ISAD is the primary technology   acid batteries,” Herrington said. “The                                       Kami Buchholz
that transforms select 2005 full-size pickup
trucks from Chevrolet and GMC into mild-       overall efficiency of the process of con-
hybrid vehicles.                               version from kinetic to electric energy,

Lotus takes the direct route to counting the cost
Gasoline direct-injection (GDI) technology     tleless for fuel efficiency with reduced         London. Their joint aim is to achieve bet-
offers many benefits for car makers, but        emissions), which is investigating the fea-     ter performance, lower emissions, and
there are several potential areas for im-      sibility of what it terms “an innovative        improved fuel efficiency.
provement that are receiving particular        approach” to managing a gasoline direct-            Operating in homogeneous mode to
attention from specialist companies, par-      injection engine. In effect it is a cost/ben-   provide high performance, and stratified
ticularly emissions performance and as-        efit ratio study. Other members of the           mode at part load for greater economy,
sociated costs. Lotus Engineering is           consortium are Siemens VDO                      GDI has many pluses. However, lean-burn
leading a collaborative research program       Automotive, Loughborough                        stratified mode precludes the use of a
called HOTFIRE (homogeneous and throt-         University, and University College              conventional three-way catalyst only; it is

42 FEBRUARY 2005   aei
                                                                                    SINGLE AXIS
                                                                             SERVO CONTROLLER
  Inlet                                             Exhaust

                                Fuel spray


Lotus is focusing on homogeneous charge direct injection technology
for the HOTFIRE program.

necessary to use a de-NOx catalyst and possibly also a particulate
trap, which adds complexity and, more significantly, cost. “Such
additional costs have, in part, been responsible for the slow
growth of sales of gasoline direct-injection powered vehicles,
because the first generation of stratified charge engines did not
achieve the fuel savings needed to justify the add-on cost,” said
Ian Watson, Lotus Engineering’s Chief Powertrain Engineer.
    Because of this, the HOTFIRE consortium believes that two
options are emerging: a second-generation stratified (spray-
guided) system delivering greater fuel savings that justifies the
add-on cost of a de-NOx system; and an homogeneous-charge
direct-injection strategy offering reduced fuel saving potential
but a lower system cost. It is the latter that the HOTFIRE pro-
gram is exploring.
    “The HOTFIRE consortium will investigate a new concept for
managing the combustion in the chamber,” said Watson. “The
research program will examine engines running permanently in
homogeneous mode while also eliminating throttling losses by
using Lotus’s Active Valve Train (AVT). This is a fully variable val-
vetrain to control the intake of air with minimal throttling losses.
With greater control of engine variables afforded by AVT, there is
                                                                         Aerotech’s SoloistTM single-axis digital servo controller
potential for remarkable strides to be made in maximizing the            combines advanced software architecture (.NET or
full capability of the internal combustion engine.”                      Windows®) with a power supply, an amplifier, and a
    Hardware for the program is being supplied by Lotus in the           position controller in a single package. The flexibility
form of two single-cylinder research engines, one with AVT and           and scalability of the SoloistTM make it the ideal
optical access, both fitted with a Siemens VDO direct-injection           controller for both small and large applications on the
system. The optical research engine will be run at Loughborough          production floor and in laboratory applications.
University, which has a laser diagnostics facility to better under-      Contact an Aerotech Application Engineer to learn
stand in-cylinder phenomena. The second engine, at University            more about the SoloistTM and Aerotech’s other motion
College London, will be used for measuring thermodynamic                 control and positioning solutions.
properties in relation to power and emissions. The HOTFIRE proj-
ect is slated for completion in September 2007. It is being part-
funded by the UK Engineering and Physical Sciences Research                                  Dedicated to the Science of Motion
Council (EPSRC).
                                                          Stuart Birch
                                                                                            Aerotech, Inc.         Ph: +1-412-963-7470
                                                                                            101 Zeta Drive         Fax: +1-412-963-7459
                                                                                            Pittsburgh, PA 15238   Email: sales@aerotech.com
                                                                         AHV1104A           USA

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