by-wire replacing mechanical systems

ELECTRIC POWERSTEERING

Electric power steeringremoves the need for hoses

and pumps, and offers fuelsavings over hydraulic steering.

HOW IT WORKSA battery-driven electric

motor provides the drive on thesteering system rather than ahydraulic device operated bythe engine. The solution alsodisconnects the steeringsystem’s power needs from theengine resulting in better fueleconomy than hydraulicsteering in a typical small car.

WHERE TO FIND ITElectric power steering is

most common in Europe andJapan but can also be found inthe US. Globally, about half of allnew cars are expected to haveelectric power steering by 2010.

The majority of the newsmall cars in Europe andJapan now have thetechnology. The 2005Volkswagen Passat is the firstvolume car above the lower-medium segment in Europe toget the technology. In NorthAmerica, electric powersteering is standard onChevrolet Malibu. Thetechnology also is available onthe new Lexus GS and typicallyis found in hybrid cars.

OBSTACLESFor suppliers, the cost of

electric power steering is still

relatively high, said PeterRieth, head of advancedengineering at ContinentalAutomotive Systems. As aresult, he said, “OEMs [are]very keen to have extrafunctions when they have

integrated electric powersteering.” Continental hasaddressed this need by usingan electronic control unit tolink its second-generationelectronic stability control toits electric power steering.Another issue is that electricpower steering is only startingto have enough power to beused in the upper-mediumsegment and above. The axleweight and the associatedtorque loads required to turnthe wheels in bigger carswould quickly drain thebattery.

PRIMARY SUPPLIERS Delphi, Koyo, NSK, Showa,

TRW Automotive, Visteon, ZFLenksysteme.

– Alex Graham

◆ 4 Automotive News Europe

By-wire replacing mechanical systems

By-wire systems can eliminate some of thejumble of hydraulic and mechanical links

in the car, replacing them with an electricarchitecture controlled by microprocessors.

A big benefit is that by-wire requiresfewer mechanical parts. That givesautomakers greater flexibility in a vehicle’sdesign. For example, the driver could bepositioned anywhere inside the car. Even inthe back seat.

Here’s why: Drive-by-wire technologyuses sensors to translate steering orbraking movements by the driver intoelectronic signals. Onboard computersinterpret the movements and relay them toelectric motors and actuators connected tothe moving parts of the car. The systemsrespond more quickly than today’s controlsand can give feedback to the computer asthey operate, allowing the car to deliverprecise performance.

By-wire systems already have replaceddirect links in one area.

“Most cars nowadays don’t have amechanical linkage between the acceleratorpedal and the fuel injection system. It’sdone electronically, and most people don’teven realize there’s no mechanical linkage,”says Steven Brown, director of NorthAmerican Programs for SKF Automotive’sdrive-by-wire business unit.

Little fanfareWhile General Motors demonstrated

drive-by-wire on its Autonomy and Hy-wirefuel cell concept cars in 2002 and 2003, moreprogress has happened with less fanfare inrecent years – especially in European-builtvehicles. Brakes, transmissions and safetysystems are bringing by-wire technologyinto the vehicle in small steps.

Electronic parking brakes such as thoseon the BMW 7 series, Audi A8 and RenaultVel Satis are examples.

Hybrid vehicles including the ToyotaPrius and Honda Civic Hybrid haveintroduced drivers to the advantages ofregenerative braking, a kind of brake-by-wire system that converts forward motioninto stored battery energy.

Shift-by-wire technology is available onhigh-end autos such as the Aston Martin DB9and Rolls-Royce Phantom, as well as someBMW, Mercedes-Benz and Lexus models.

Also, comfort and safety systems such asadaptive cruise control, automated parallelparking and steering intervention for lane-keeping, such as those shown byContinental Teves at last month’s IAA inFrankfurt, rely on by-wire control of somesteering and braking functions.

Any supplier doing work in the by-wirearena will tell you there are obstacles to massadoption of the technology. The auto industryis used to the highly refined technologycurrently in place. Also, car buyers are notclamoring for a change and some early by-wire technology features haven’t sold well.Until by-wire systems combine moreadvantages into a single system, adoption ofthe technology will be gradual.

By-wire adaptation stumbled whenpromised 42-volt electrical systems failed tobecome an industry standard, but new dual-voltage systems offer promise of enoughpower for high-force uses such as brakingand steering.

A European consortium called SPARC –short for Secure Propulsion using AdvancedRedundant Control – and organized byDaimlerChrysler and Fiat is working on by-wire accident-avoiding truck and cardemonstration vehicles. ANE

Chassis & Materials

October 31, 2005

Losing the linkPrimary suppliers of by-wire solutions:

● Bosch ● Continental● Delphi ● Denso ● Johnson Controls ● Hitachi ● Magneti Marelli ● Magna Steyr

● Mitsubishi Electric ● Motorola ● Siemens VDO● SKF ● Toyota ● TRW ● Valeo ● Visteon

TIM MORAN

AUTOMOTIVE NEWS EUROPE

Steer-by-wire means the end of the mechanical connection between the steering wheeland the road wheels. Electronically controlled actuators set the steering angles.

Delphi supplies its column-drive electric power steeringto the Opel Meriva. Theelectric motor is mounted onthe steering column (circled).

AN_suppl_051031_4-6.qxd 19.10.2005 19:22 Uhr Page 4

CONTINUOUSDAMPING CONTROL

Continuous damping controlis an electronic system that

can adjust the tension in ashock absorber to create amore dynamic ride quality forthe vehicle. The technologyincludes the use of magneto-rheological fluid that can bemade syrupy or water-likedepending on a mild electricalcharge. Other suppliers useelectronics to continuouslyvary the valves that controlfluid flow within the shock.Both systems let the shocksadjust to road input formaximum stability, handlingand comfort.

HOW IT WORKSIn US supplier Delphi’s

system the oil normally used inshocks and struts is replacedby a magneto-rheological fluid,which surges through specialorifices to dampen axle motion.When an electromagnetic coilinside the damper’s piston isactivated, the fluid’s

components align differently,rendering it thicker or thinneras needed. A computercontrols the coil to provide veryfast reaction to road inputsbased on input from sensorsthat monitor body and wheelmotions. Others, including ZFSachs of Germany, use a valvecontrol mechanism fordamping. Continuous valvecontrol uses a combination ofacceleration, displacement andsteering sensors to help anelectronic control unit choose adamping level for thesuspension. An electronic valveon each shock or strut reacts tothe computer commands byrestricting or enlarging thechannel that oil flows through.

WHERE TO FIND ITThis technology is mainly

seen in high-end and sportscars, but that is starting tochange. “Now it’s moving intomedium-class cars,” saidThomas Kutsche, head ofdevelopment of variabledamping systems at ZF Sachs.“There’s a general trend in

this direction.”In 2004, ZF Sachs provided

continuous damping controlto 175,000 vehicles. For2005, it will supplyabout 225,000vehicles. The newFord Galaxy largeminivan willhave Ford’snew continuousdampingcontrol.

OBSTACLESThis technology

is moving slowerinto mass-marketvehicles than otherssuch as tirepressuremonitoring systems orelectronic stability controlbecause it offers fewer clear-cut benefits to the consumer.The main issues are cost andmaintenance. Shocks are ahigh-wear item, which meansreplacement could beexpensive. Also, integratingelectrical, mechanical andhydraulic components in an

exposed underbody locationincreases the complexity ofdiagnostics.

PRIMARY SUPPLIERSThe main suppliers are

Delphi, Tenneco Automotive,ZF Sachs, Continental Tevesand most other shock absorbermakers.

– Alex Graham

◆ 6 Automotive News Europe

ELECTRONIC STABILITYCONTROL

E lectronic stability control helps preventskids and swerves that can happen in an

emergency. This makes ESC especiallyeffective in combating rollover accidents.

HOW IT WORKSThe electronic control unit at the heart of

the ESC system brakes each wheelindividually and decreases engine torque tomaintain a stable direction of travel. ESCcontinuously monitors key inputs such asyaw rate and wheel speed.

WHERE TO FIND ITThe overall installation rate in 2004 was

about 40 percent in western Europe. It tookantilock brakes twice as long to achieve a similar level, according to data fromGerman supplier Robert Bosch.

A law adopted in August 2005 requires USregulators to develop standards aimed atpreventing rollover crashes. Even withoutthe new law, the US National HighwayTraffic Safety Administration appearedheaded toward adoption of an antirolloverrule. Automakers also have been increasinginstallation rates for electronic stabilitycontrol systems in the US. As a result,installation rates should grow to about 50 percent of all passenger cars in NorthAmerica by 2009.

TRW Automotive has cooperated withGoodyear to develop ESC that can be linkedto the characteristics of the tires. New tiresare often fitted with identity tags. Usingthose tags “we can tailor the ESC softwareto suit different tires and wheels,” says PhilCunningham, product business director forchassis systems at TRW Automotive. “For

little or no cost, we can increase theperformance of the ESC.”

OBSTACLESConsumer and dealer awareness of ESC

remains relatively low, especially in NorthAmerica. As a result, Bosch in particularhas put considerable effort into holdingevents to raise awareness amongconsumers. ESC systems are increasinglyrequired to interact with a number of othersystems in the vehicle – such as steering,adaptive cruise control and tires –increasing the risk of electronics problems.

PRIMARY SUPPLIERS Advics, Bosch, Continental Teves, Delphi,

TRW Automotive.– Alex Graham

Chassis & Materials

October 31, 2005

PLASTIC PARTS

S uppliers are substituting super-strength plastic for steel in some

components such as front-end modulesand instrument panels. It’s a trend thatbegan in Europe and is finding its way intoNorth American vehicle programs.

HOW IT WORKSInjection molded plastic is mixed with

glass fibers to create high-strengthstructural frames and carriers forcomponents. These structural parts arestronger than standard plastic parts.

WHERE TO FIND ITFaurecia of France announced in July

2005 that it won a contract with the Chryslergroup, which includes Chrysler, Dodge andJeep, to make what it calls High IntegratedModule door systems in the US using acarrier made with an injection-molded long-fiber thermoplastic. The module consists of asingle structural plastic part that includesmechanical functions such as the window liftunit, internal and external handles, speakersand electrical harness. In addition,ArvinMeritor recently introduced what itterms as its Highly Integrated Plastic doormodule, which also uses a thermoplasticcomposite to replace a steel inner structure.

OBSTACLESAlthough the price of steel is high, the

resins used to make high-strength plasticsmay cost more per pound than steel.

PRIMARY SUPPLIERS Faurecia, ArvinMeritor, HBPO (a joint

venture with Hella, Behr and PlasticOmnium), RheTech Inc., Owens Corning.

– Rhoda Miel, Chaz Osburn

The modulator (1) and electroniccontrol unit (2) are at the heart ofContinental’s second-generationelectronic stability control system. The system provides individual wheelbraking to keep a vehicle from slidingout of control.

Sensors for acceleration, displacementand steering help an electronic controlunit (left) choose a damping level forthe suspension in ZF Sachs’ system.

AN_suppl_051031_4-6.qxd 19.10.2005 19:22 Uhr Page 6