INDUSTRIAL MANAGEMENT & THE AMAZING Infinite- Ratio 'Gearbox'

This fuel-saving is going into a new Saturn SUV, among other vehicles. At its heart is--a very special belt -like the_one shown here.

No, this isn't a chic necklace but a superstrong steel belt that transmits power from engine to wheels.

ack in 1989 I was pilot• belowdecks to the crew members in charge gear ratios to suit the conditions of the ing a little mini• of actually opening the steam valves that moment. With its tiny 1.2-liter engine and car called the Justy send power to the propellers. There was an slo-mo throttle response, the Justy ECVT ECVT through the unsettling time lag before the car finally wasn't suited to American driving condi• rowdy traffic on Man• got up and went. tions and in a few years faded from the hattan's West Side The Justy was equipped with a contin• scene. But the idea of a thrifty transmis• Highway_ Spotting an uously variable transmission, or CVT, and sion with an infinite number of ratios, in• opening ahead in the I was experiencing what engineers at the stead of just a few, stayed alive in engi• adjacent lane, I nailed the throttle and be• time called the "rubber-band effect." neering labs around the world. gan steering to the right. That's when I Justy owners soon learned not to expect Now there's a new generation of CVTs narrowly missed sideswiping a big acceleration until a second or two after that really work. They are available in a Oldsmobile. Time expands a lot at such applying the throttle. It took that long for number of small European and Japanese moments,and as the milliseconds marched mysterious electrohydraulic hardware un• cars, and U.S. automakers are tooling up to by I felt like the captain of a huge ship der the hood to adjust the transmission's produce them as well. A small CVT• whohad ordered a change of speed. It was equipped sport-utility vehicle from GM's as if the first officer had briefly second• Saturn division is slated to go into produc• guessed my command before relaying it by Stuart f: Brown tion in the fall of 2001, and more American

November 13, 2000 FOR TUN E • 384[Y] GOING GEARLESS offerings will follow.'Once economies of Cars and light trucks with CVTs consume scale kick in, CVTs should cost less to make than the conventional automatic 6% to 15% less fuel, and automakers want to transmissions used in 90% of the vehicles sold in the U.S. be ready if consumers rediscover fuel efficiency. Cars and light trucks with CVTs also consume 6% to 15% less fuel than auto• be appearing in some light truck models. David Cole, director of the University matics. Even before the recent spike in gas• Arv Mueller, GM's group vice president of Michigan's Office for the Study ofAu• oline prices, this appealed to companies for powertrains worldwide, told FOR• tomotive Transportation, reports that like GM and Ford, which have seen their TUNE, "We think the CVT is a really cost• CVTs have shown up on the radar screen federally mandated corporate average fuel effective way to get a big chunk of fuel in his group's most recent survey of in• economy (CAFE) numbers dragged down economy, and in this business you'd kill dustry trends. "CVTs have a minimal pres• by all the thirsty trucks and SUVs and min• for half a percent. We're thrilled with the ence today," Cole says, "but we project ivans they're selling. Missing the magic performance and the feeling of it." that by 2009 they will account for 7% ofall CAFE number can cost them stiff fines. The newgeneration of CVTs isjust one of passenger-car transmissions in the U.S., And with fuel prices high, the automakers several technologies auto engineers have in which would be about 560,000 units." want to be ready if consumers rediscover their toolbox for boosting fuel efficiencyas That estimate could turn out low.In a fuel efficiency. well as driving performance. Among the joint venture, Ford and the German trans• GM and Ford have recently been in a others are direct fuel injection and camless mission maker ZF are outfitting a plant in public-image battle over which company's valve actuation, which uses hydraulic or Ohio to crank out as many as a million vehicles will have the better fuel economy electrical actuators to precisely tailor the CVTs a year by 2005. That doesn't count -particularly in SUV s-and GM vice timing and degree of valve openings and CVTs that GM will bring in from a plant chairman Harry Pearce has said CVTs will closings to improve engine breathing. in Hungary owned by its Opel subsidiary.

Shifting Without Gears

The transmission shown here replaces sets of toothed wheels with a lower sheaves are close together (left diagram), the effect is the equiv• sophisticated belt-and-pulley mechanism called a variator. The pulleys' alent of a small gear driving a large gear, as when a car is pulling tapered halves, or sheaves, slide close together or far apart, making away from a stop. Reversing the sheaves' positions (right) creates the possible infinite variations in the diameters the belt wraps around equivalent of a high, cruising gear ratio. A key component is the unu• on each pulley. When the upper pulley's sheaves are far apart and the sual belt, which transmits power by pushing instead of pulling.

384[Z] • FOR TUN E November 13, 2000 Nissan, and Subaru. These highly engi• neered stainless-steel beauties are not the V-belt from your father's rototiller. As Van Doorne's engineers moved awayfrom rub• ber belts and into more rugged metal de• signs, they dropped the convention of one pulleypulling the other via the belt, and hit upon the idea of a belt that pushes. It seems utterly counterintuitive at first, like pushing on a rope. But it works. The mighty push belt is made up of hun• dreds of flat stamped-steel elements with notched edges through which run thin steel bands that hold them together to form a loop. The whole shiny thing looks like a trendy high-fashion necklace. As the CVT's driving pulley is turned by the en• gine, each element of the belt pushes against the next, transmitting torque to the driven pulley, which connects to the axles and wheels. By constantly pinching the belt with considerable hydraulic force regardless of how close or far apart they That's Arv Mueller, GM'spowertrain boss, with the new Saturn transmission. It's a "really cost-effec• are, the sheaves keep the belt from devel• tive way to get a big chunk of fuel economy," he says. "In this business, you'd kill for half a percent." oping slack or slipping on the pulleys, which would destroy the variator. In Europe and Japan, where fuel prices times that amount of power. Eventually Van Doorne's patent portfolio bulges have long been sky-high and drivers have they could outnumber today's automatics, with metallurgic, heat-treating, and metal• shied away from automatic transmissions which are sometimes called step-gear forming wisdom gleaned during years of because they gulp more fuel, CVTs may transmissions because of the rigid ratios sticking with the tough challenge of mak• catch on even faster. defined by their three to five meshing sets ing belts survive ever higher power levels. If you have ever been aboard a snow• of toothed gears. Elias van Wijk, the engineer in charge of mobile, you've experienced a CVT, per• the company's work with GM, says belts haps without quite realizing what was go• now in production can live with about 160 ing on. A snowmobile's rudimentary CVT foot-pounds of torque (the output of a consists of two pulleys connected by a transmission mechanisms that could 150hp engine) and that heftier versions stout rubber belt. One pulley is driven by Inventorsconnectautomobilesthesinceenginehavethesweatedtodaystheofroadoverthe throughsteplessearliest now in development should be able to han• the engine, and the other one drives the infinitely variable ratios. Today's prevalent dle up to 310foot-pounds, which gets into track mechanism that propels the sled for• belt-type CVT technology was developed full-sized pickup-truck territory. ward. The tapered halves of the pulleys, by Dutch engineer Dr. Hub Van Doorne, An ironic aspect of U.S. automakers' in• known as sheaves, form a V-shaped notch whose company, Van Doorne's Trans• terest in CVTs is that they aren't intended that widens or narrows as you ride the missie, built a CVT called the Variomatic to fix something that's broke or banish a snowmobile. This forces the belt to move for the DAF, a small car that went into sales-destroying irritant from the product closer or farther from the centers of the production in the Netherlands in 1958. On the contrary, American customers are sheaves, effectively varying the diameters The Variomatic's rubber V-belt sufficed generally quite content with their auto• the belt wraps around. to handle the modest 30hp output of the matic transmissions. With a bit of luck, the As one pulley's diameter gets smaller DAF's tiny 0.6-liter two-cylinder engine. approximately 500 parts inside one of and the other's gets bigger, or vice versa, Van Doorne, in Tilburg, the Nether• these modern hydro-electro-mechanical the mechanical ratios between them shift lands, was acquired in 1995 by Germany's wonders-compared with about 180parts in a seamless continuum. Like other sim• Bosch Group and has become the Intel of in a typical engine-will do their jobs with• ple, useful mechanisms that somebody the CVT world. Its belt-and-pulley set, out complaining for the life for the car. else has perfected, the heart of a CVT called a variator, as well as its engineering looks right'and obvious and makes you expertise, are in almost all the belt-type wonder, Why didn't I think of that? CVTs built. The other significant CVT de• neers at GM's powertrain division CVTs were offered in little 1980s cars sign is the quite different and costlier "to• in Pontiac, Mich., who are working like the 73-horsepower Justy because the roidal" type offered by Nissan (see box), Thison thepresentscompany'sichallengefirst CVTto thevehicle,engi• technology of the day couldn't handle the This year Van Doorne expects to pro• They are struggling to make it perform in power output of bigger engines without duce 430,000 of its ultra-tough CVT belts, such a way that drivers will be largely un• going to pieces. But all that is changing. ramping up to 1.5 million belts by 2005. aware of anything different. under the Engineers have learned to make CVTs They're currently used in CVT cars built hood. They figure, Why tinker with suc• that can survive in cars producing four by Fiat, Lancia, Rover, Honda, Mitsubishi, cess? GM is putting its first CVT into the

384[BB] ., FOR TUN E November 13, 2000 GOING GEARLESS

four-cylinder version of a 2002 Sat• The CVT• urn SUV that will reach show• equipped rooms about 12months from now. Saturn SUV Judging by a drive in a "mule" test goes on sale vehicle equipped with a develop• next fall. ment version of the SUV's 2.2-liter CVT powertrain, customers will be treated to quite a creamy-feeling ex• perience, with no more noise than usual. Still, the sensation is novel. When you tios to let the engine run at wider, more ef• a comparable car with a traditional auto• step on the gas pedal with a conventional ficient throttle openings where pumping matic transmission. There have even been automatic, the vehicle pulls smoothly losses go down, while keeping rpms rela• rumors that Honda may roll out a CVT• away and you feel slight surges in the tively low to save fuel. equipped motorcycle, which would be power delivery as the transmission up• Part of the trick involves using a throt• something different indeed. shifts through its gears. Things feel dif• tle-by-wire setup instead of a direct me• Every car has a mechanism known as a ferent with a CVT, which holds the en• chanicallinkup between the driver's foot launch device to connect the engine's spin• gine speed within a narrower range. on the gas pedal and the throttle plate. A ning crankshaft with the transmission. There are none of those familiar engine• control chip, which considers various fac• Honda's Civic HX uses the most fuel-effi• speed run-ups and abrupt slowdowns as tors including engine speed, vehicle cient launch device, which is a multiplate an shifts gears; speed, and how far and abruptly the clutch pack that disengages when the car instead, the engine's revolutions per min• driver has pushed the gas pedal, instructs comes to a stop and idles, then hooks back ute (rpms) just slide up and down some• an electrical actuator that moves the up again when the driver steps on the ac- what as the vehicle accelerates and slows. This absence of familiar automatic• shifting cues in the seat of the driver's A CVT car can feel as though it's accelerating pants can make a CVT car feel as though it's accelerating sort of slowly. But the slowly. But some CVT cars can outsprint even a speedometer says otherwise. Track tests prove that some CVT cars can outsprint hotshot driver working a . even a hotshot driver working a manual five-speed transmission. One reason: plate. The CVT is yet another in a series celerator. Karl Janovits, GM's chief CVT There are no pauses in power delivery, of automobile control mechanisms that engineer, says he and his colleagues were which are unavoidable when traditional have benefited from today's cheap, smart willing to sacrifice a bit of fuel efficiencyin toothed gears are shifted. microprocessors. exchange for a smoother launch from While CVTs take a bit of getting used CVT control chips can be programmed standstill than a clutch pack is able to de• to, the engineers are doing a lot to make with different "ratio maps" to suit the liver. Their launch device is the same type them endearing. The Saturn SUV will driver's mood. For example, when a rapid of used with conven• have upshift-downshift buttons on the and deep push on the gas pedal signals tional automatic transmissions. steering wheel that drivers can tap when that the driver wants to sprint, the chip To understand how a torque converter they're feeling nostalgic for the discrete consults a performance-ratio "map" in its works, take a bagel and slice it the long gear ratios of yore. The CVT's control memory that temporarily sacrifices effi• way.Now scoop out the halves and put lit• chip will respond by adjusting the pulley ciency for acceleration by letting the en• tle dividers, or vanes, in them so they re• diameters to preset ratios stored in its gine rev faster. Once at cruise speed, the semble circular ice-cube trays. That's what memory. Otherwise the CVT will follow chip reverts to a fuel-saving map. I drove the two halves of a torque converter look its own muse, selecting the most fuel• a CVT-equipped Honda SUV called the like. In operation they face each other efficient ratio as conditions vary. HRV, which is sold in Japan and Europe. without touching in a bath of automatic The fuel-efficiency gains that a CVT de• It has steering-wheel buttons that allow transmission fluid, and as the driving half livers come from improving the fluid dy• the driver to choose sport or cruise modes. connected to the engine revs up, the swirl• namics of the engine's breathing. Gaso• They're fun to switch back and forth. ing fluid drags along the driven half. This line engines inhale air through an intake Americans who itch to get behind the fluid-coupling device is the reason auto• manifold that contains a round, pivoting wheel of a CVT car right now can head to matic-transmission vehicles have a slight plate called a butterfly valve. Stepping on a Honda dealer and ask if there's a Civic forward creep at idle that Americans are the gas pedal opens the plate, admitting HX coupe in stock. There probably won't fond of, as well as a creamy-feeling more air, which the fuel-injection system be, as the company hasn't promoted the launch. GM thinks the CVT should feel complements with gasoline, causing the HX very well. But it has a nicely engi• the same way. engine to rev up. At idle speed and at low neered Van Doorne-belt CVT that made Aside from the progress Van Doorne throttle, however, the constriction caused it the first automatic-transmission car on has made with its belts and pulleys, the by the narrow opening inhibits the air the EPA's list of top ten fuel-economy main development that's making CVTsvi• flow, causing what are called pumping champs. The recently unveiled next• able today is a smart, fast electrohydraulic losses. With its clever electronic control generation Civic line continues to include control system. Its key components are the system, the CVT forever juggles gear ra- a CVT model, which costs $200 more than microprocessor and a quiet-running, high-

384[DD] • FOR TUN E November 13, 2000 GOING GEARLESS pressure hydraulic pump that can generate In a plant near Cincinnati, a joint venture of Ford the pulley-clamping forces needed to keep the belt from slipping. "Today the system Motor and Germany's ZF is awaiting $500 million can change ratios quickly and ensure the durability of the belt and sheaves, which worth of new machine tools for making CVTs. just cannot be allowed to slip," says Karla Berger, GM's CVT calibration manager, hicles with less than 260 foot-pounds of get us 6% to 10% better fuel economy, and who predicts, "We are going to have a engine torque," which means most front• they represent an evolution in shift quality zero-maintenance transmission." wheel-drive vehicles. ZF engineers are that will enhance the driving experience." Like all CVTs, it will also have an unu• refining the design of a belt-type CVT From 1988 to 1997, Ford built a low• sually broad range between the highest that can handle a maximum of 180 foot• torque CVT in France called the CTX that and lowest multiples of engine speed to pounds of torque, or roughly the output was in about 200,000small cars sold in Eu• wheel speed. This provides both a strong of a 2.5-liter V-6. A higher-torque model rope. "Like a lot of early CVTs, the CTX launch and low engine rpms at cruising is also planned. had basic hydraulic controls, and we're able speed to improve fuel economy. In GM's ZF's origins go back to Count Ferdi• to do a much better job of making smooth CVT, the multiple will vary by a factor of nand Zeppelin of airship fame. (In Ger• ratio changes now with electronic controls," 5.9 to 1. That compares with ratios of only man the letters stand not for "Zeppelin saysCraig Renneker, executive engineer for 4.3 to 1 and 5.1to 1,respectively,in the com• factory" but for "gear factory.") The new automatic transmission programs. Like pany's four- and five-speed automatics. company has long experience in making GM, Ford has chosen to use a torque con• Janovits, who has worked on CVT pro• manual and conventional automatic verter as its launch device. grams at GM since 1984,says that the belt• transmissions; it has been working on Van Doorne isn't totally without com• and-pulley variator sets, which Van CVT designs for a decade and owns a petition in CVT belts. sells an A6 Doorne will supply to the company's plant Belgian plant that produces a low-torque model in Europe that's equipped with a in Hungary, are fairly costly. The pulleys CVT used in a Rover vehicle. One of the "" CVT that uses a proprietary, must be made from forged steel, he ex• tough tasks facing the engineers, Kehr fierce-looking pull-chain made by LUK, a plains, which is then precision ground and says, is making sure the CVT can deal German driveline components maker. heat-treated. Compared with GM's four• with the "back push" that occurs when a Audi says this A6, which is the highest• speed automatic, however, the CVT has car towing a trailer crests a hill and be• torque front-drive CVT car currently in 45% fewer parts, and Janovits expects it to gins descending. The CVT's controller production, may be exported to the U.S. cost no more initially than the older gear• has to be smart and quick enough to next year. Its 2.8-liter V-6 engine produces box. With mass-production economies, he clamp down on the pulleys and avoid belt 207 foot-pounds of torque. LUK's chain says, "it has the potential to get cheaper." slippage that could finish off the pricey consists of several hundred thin steel variator. plates connected with pins like a bicycle Ford managers won't reveal exactly chain. The system's pulley sheaves actu• topic No. 1 at ZF Batavia, the where CVTs will first appear in their ally squeeze the ends of the pins, which Ford-ZF joint venture near Cin• model lineup, but they are clearly itching protrude beyond the plates. Audi brags Masteringcinnati that'sCVTtoolingmanufacturingup for pro•is to get the fuel-saving CAFE benefits. that the chain wraps more tightly around duction starting early in 2002. The 1.8• "We're excited about the technology, and the pulleys than a belt can, giving its CVT million-square-foot plant at Batavia, we're in the process of a lot of develop• an unmatched ratio range. Ohio, is only half-occupied with machin• ment work to see what potential it has for Engineers familiar with Audi's CVT ery that produces four-speed automatic some of our smaller front-drive vehicles," development program say it took a lot of transmissions used in such Ford products says Barbara Samardzich, chief engineer sound-deadening material to suppress the as the Contour and Cougar, and in the for automatic transmissions. "CVTs can LUK chain's whining sound, but the re- Mazda 626. (The 1981-vintage factory's street address is 1981 Front Wheel Drive. Get it?) The unused space awaits $500 million worth of new machine tools for making CVTs using Van Doorne belt• and-pulley sets. The plant will sell the transmissions to Ford and other automakers. As CVT production ramps up in Batavia, tradi• tional automatic-trans• mission building will wind down. Karl Kehr, ZF Batavia's chief financial officer and a for• mer Ford guy, boldly predicts, "We The first believe that in eight to ten years there CVT car, the won't be a conventional automatic trans• tiny, Dutch-built mission on the market for front-drive ve- OAF,was introduced in 1958.

384[FF] • FOR TUN E November 13, 2000 GOING GEARLESS suit is a sweet-driving system that's a crop of fuel-saving technologies, with CVT has the best return on investment." benchmark for competitors. Its launch de• which it may later be combined. But to You can't add up the incremental fuel• vice is a multiplate clutch designed to de• many auto executives, the CVT alone ap• saving benefits of these technologies liver a slight amount of creep at a stand• pears to offer a satisfactory payoff for without some losses, Mueller notes: "Six still, and there's a six-speed "manual" now. "We have to decide where to spend percent plus 6% plus 6% does not equal mode, like the Saturn SUV's, that allows our lunch money," says GM powertrain 18%. The total will be less, so we are the driver to control the timing of steplike boss Mueller. "Camless valve actuation, starting with the highest-value system, gear changes. direct fuel injection, and the CVT are which is the CVT." 0 The CVT has a head start in the latest three ways to improve efficiency, but the FEEDBACK: [email protected]

Nissan's 'Toroidal' Approach by 10% when compared with a conventional automatic trans• and-pulley mechanism. Auto men have tinkered for mission. The Extroid's mechanism uses rotating, parallel years with "toroidal" mechanisms, so-called because disks with concave faces connected by pairs of "power roll• NOttheirallkeycontinuouslyfunctions variabletake placetransmissionsin a doughnut-shapeduse a belt• ers." When the engine is running, it spins the input disk, internal space where rolling elements transmit power at var• which turns the power rollers, which transmit the motion to iable ratios (see below). General Motors, using a Citroen de• the output disk and from there to the road. sign from the 1920s, had a fully developed toroidal CVT be• When the rollers swivel at different angles against the fore World War II and continues to study the design for use concave surfaces ofthe disks, which face each other, their in high-powered vehicles. points of contact produce varying multiples of engine In Japan, Nissan sells two luxury cars, the Cedric and the speed to wheel speed. Thus, when one side of the power Gloria, equipped with a toroidal CVT called the "Extroid." roller contacts the small-diameter area of the input disk, the power roller's other side con• ~ tacts the large-diameter area of the ~ output disk. The result is a low startup ratio equivalent to a small gear driving a big one. The power rollers create a "high gear" effect at the opposite angle and can swivel to provide a smooth spectrum of ratios in between. Engineering headaches have . dogged the toroidal CVT's develop• ment. One of the biggest issues was coming up with metal disks and rollers that could withstand the three to ten tons of pressure at their points of con• tact. Nippon Steel, a bearing manu• facturer whose metallurgists have long This continuously variable transmission, available on two Nissan luxury cars sold in Japan, worked on toroidal CVT develop• uses rollers instead of a belt. By tilting at different angles, they transmit power at varying ment, supplies the microfinished disk ratios. At low speed, for example (left), the rollers' tilt creates the effect of a small gear and roller components for the Extroid. driving a big gear. At a high cruising speed (right), a reverse tilt creates the opposite effect. They are made from a special steel al• loy of unusually high purity into which These real-wheel-drive cars have turbocharged V-6 engines carbon is deeply infused to impart the required toughness. that put out a hefty 285 foot-pounds of torque. Engineers Another major hurdle was coming up with a transmission who have driven the cars report that the novel CVT delivers fluid that could provide the metal-protecting benefits of oil, power quite effectively to the asphalt. Says the University of but without oil's slipperiness, which would render the disks Michigan's David Cole: "It's terrific, very smooth, respon• and rollers incapable of transmitting torque. Idemitsu, an• sive and quiet. I am particularly impressed with the power other supplier, figured out the weird chemistry needed for it can handle compared to other C.:vTs." what it calls "traction oil." This special sauce contains long• Jatco, the Japanese transmission maker, builds the Ex• chain molecules with hooklike projections that interlock and troids for Nissan on a low-volume basis. They come as a become grippy when subjected to the extremely high pres• $2,500 option and, the company says, improve fuel economy sures found at the disk-to-roller contact points ...

384[JJ] • FOR TUN E November 13, 2000