WORKING PAPER 2018-15

Fuel-efficiency technology trend assessment for LDVs in : technology

Authors: Zifei Yang, Yong Chen, Aaron Isenstadt Date: 17 September 2018 Keywords: transmission technology, fuel efficiency, passenger

1 Background Fuel e ciency Fuel-consumption standards drive technologies down China’s use of fuel by the on- road sector and encourage the uptake of advanced vehicle-efficiency tech- Advanced Vehicle Thermal Hybrids and Transmissions nologies. Understanding the need for engines technology management electrifction a policy roadmap and long-term strat- egies to provide certainty for long- Figure 1 Categorization of fuel efficiency technologies in the working papers term fuel consumption, technology advancement, and potential compli- This series of technical working papers This research relies on information ance costs for manufacturers, China is aims to provide a comprehensive from publicly available sources, third- looking ahead to advance post-2020 understanding of the current availability, party databases, and information standards for light-duty vehicles. effectiveness, and future market from the participating partners. Our In its “Made in China 2025” strategic penetration of key fuel-efficiency approach includes: initiative (MIIT, 2015), China set a 2025 technologies that manufacturers are • A detailed literature survey, fleet efficiency target of 4 L/100 km likely to use in China by 2030. This including both Chinese and for passenger , a 20% decrease information enables a more accurate, global regulatory documents, from the 2020 target of 5 L/100 km. In China-specific understanding of future official announcements, and the Technology Roadmap for Energy technology pathways. industry and academic reports. Saving and New Energy Vehicles We group technologies into sev- published by the Society of Automo- • Analysis of databases from Polk eral categories: advanced engine, tive Engineers of China (SAE China, and Segment Y. transmission, vehicle technologies, 2016), a 2030 fleet efficiency target thermal management, and hybrids and • Conversations with manufactur- of 3.2 L/100 km was set. To evaluate electrification (Figure 1). The specific ers, tier one suppliers, research whether and how these targets can be technologies we considered include entities, and domestic and inter- met, it is essential to understand what those that are available today and national experts. technologies will be available within others that are under development the 2020-2030 timeframe and what For each key technology, we discuss and expected to be in production in the costs of applying those technolo- how it reduces passenger-car fuel the next 5-10 years. gies in the Chinese market will be. consumption, its effectiveness in

Acknowledgments: The authors thank the Energy Foundation China for sponsoring this series of studies. We greatly appreciate valuable comments from Hui He (the ICCT) and Ameya Joshi (Corning).

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Manual Automatic reducing fuel consumption, and its 100% current level of application or poten- tial application in the China market. 90% Wherever applicable, we compare 80% technology trends in China with those in the United States and the European 70% Union to reflect potential technology 60% pathways in the long term. 50% This working paper assesses tech- nology progress and new develop- 40% ments in transmissions. 30%

20% 2 Introduction 10% Because of lower costs and fuel consumption, manual transmis- 0% sions (MTs) have been the main- 2007 2008 2010 2011 2012 2013 2014 2015 2016 2017 stream technology for decades in Market penetration of manual and automatic transmissions in China, China. However, MTs’ leading market Figure 2 2007-2017 share has eroded in recent years as demand for automatic transmissions to its most efficient speeds more pairs of concentric cones, with grew in response to an expanding of the time. This significantly infinite variability between the vehicle population and increasing reduces the efficiency gap. maximum and minimum gear city congestion. The market share • Dual-clutch transmissions ratios. The efficiency of the of MTs has decreased from a peak (DCTs) consist of two separate transmission is reduced by fric- of more than 70% in 2009 to 39% manual transmissions with odd- tional losses related to clamp- in 2017 (Figure 2). Today, automatic numbered gears on one shaft ing forces on the belt/chain transmissions account for the major- and even-numbered gears on a as well as the need for high- ity of new vehicle sales. second shaft. Each shaft has its pressure hydraulics. However, the system produces an infinite The automatic transmission (AT) own clutch, and the gear on one number of engine/wheel speed market is split among several types shaft is disengaged at the same time that the gear on the other ratios, allowing the engine to in China: shaft is engaged. This design always run at optimal speed/ • Conventional ATs traditionally approaches the efficiency of an load points, thus maximizing use a torque converter and a MT and offers the potential for engine efficiency. set of planetary gear sets. Shift- smooth and quick shifts without • Automated Manual Transmis- ing gear ratios is accomplished torque interruption. Because a sions (AMTs) are manual trans- through the hydraulic selection vehicle with a DCT must start missions that employ an electro- of a specific planetary gear set. moving while engaging one mechanical clutch actuator to Although the efficiency of an MT clutch, manufacturers use either automatically complete the shift. is generally higher than that of a a wet hydraulic clutch (wet DCT) AMTs combine the efficiency of hydraulic AT, advances in torque or an accumulator and high- MTs with the convenience of ATs converter lockup and hydraulics pressure hydraulic (dry DCT) to as the gears shift automatically. have improved the efficiency of improve launch performance. AMTs have been widely used on ATs. As the number of gear ratios • Continuously variable transmis- commercial vehicles in . increases to six or more, ATs sions (CVTs) conventionally use Unlike DCTs, AMTs use a single allow an engine to operate closer a belt or a chain to connect two gear shaft.

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Table 1 shows fuel-consumption Table 1 Projected benefits and costs of considered transmission technologies benefits and costs for different Fuel-consumption Direct manufacturing transmission technologies based on reduction cost (CNY*) estimates by the U.S. National High- U.S. U.S. China China way Traffic Safety Administration estimate estimatea estimateb estimateb (NHTSA), Environmental Protection (2025)a Relative to Agency (EPA), and the China Auto- 6-speed MT 2.0%–2.5% 2.0% 1107 1800 5-speed MT motive Technology and Research 5-speed AT 1.1%-1.6% 448 4-speed AT Center (CATARC). It includes estima- 6-speed AT 1.7%–2.2% -70 4-speed AT tions of different types of transmis- 8-speed AT 6.4%–7.8% 5.74% 231 5500 4-speed AT sions, aggressive shift logic, early -1126 (dry) torque converter lockup, and high- 6-speed DCT** 5.7%–8.1% 4-speed AT efficiency gearbox. -794 (wet) 4% 1700 -154 (dry) As Table 1 shows, DCTs tend to 8-speed DCT** 9.7%–12.6% 4-speed AT -179 (wet) exhibit higher cost-effectiveness CVT 6.0%–8.7% 3.75% — 1200 4-speed AT in both U.S. and Chinese estimates Aggressive shift as they generate significant benefit 5.1%–7.0% 141 No ASL logic(ASL) while costing less than a conventional Early torque No early torque 4-speed AT (4AT). MTs consume less 0.4%–0.5% 128 converter lockup converter lockup energy than automatics, but ATs High-efficiency No high-efficiency 4.3%–5.7% 1043 select the optimum gear ratio at all gearbox gerabox times. So switching from a manual to an automatic with more gear ratios— * Exchange rate between USD and CNY is 1:6.4 ** Fuel consumption reduction estimation includes impact of AMT particularly a DCT—can offset the a U.S. EPA and NHTSA, 2012 advantage of a conventional MT and b CATARC, 2017 lead to greater fuel efficiency overall.

Others MT AT 3 Current status 2% 4AT 3% Most ATs and CVTs today have adopted torque converter lockup AT to reduce fuel consumption by low- 8AT 3% MT 33% ering the loss of power transfer 39% 5AT 9AT through the fluid inside the torque 6AT 25% 1% 1% converter and from slippage during CVT DCT rapid acceleration. Despite differ- DCT ent transmission control strategies, CVT 12% 5MT 33% 14% the lockup is usually triggered at 7DCT 9% higher speeds. At lower vehicle 6MT 6% CVT 14% 6DCT 2.3% speeds, torsional energy is harder to dampen, and it can create shak- Figure 3 Market penetration of transmission by type among passenger cars in 2017 ing or shuddering as it passes through the vehicle. Thus, early Atenza is mated with a 6-speed According to Table 1, ATs with torque converter lockup requires automatic transmission (6AT) with aggressive shift logic (ASL) could upgraded materials to withstand early torque converter lockup. This also significantly improve fuel effi- higher loads (Isenstadt, German, expands the lockup range from ciency compared with conventional Burd, and Greif, 2016). Only a few 64% on current 5ATs to 89% over ATs without ASL. ASL increases models enable lockup at lower the New European Drive Cycle efficiency through downspeeding, speeds. For example, the Mazda (NEDC) (Mazda, 2018). which enables earlier upshift—at

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lower rpm during acceleration—and Others AT DCT CVT MT Others shift optimization. This requires con- 2% 100% stant monitoring of all gear options and selecting the gear that puts the AT 80% 15% engine in the most efficient operat- 60% ing zone. This paper does not have DCT 7% information on shift control strate- CVT 5% 40% gies of vehicles in China. 20% As shown in Figure 3, the conven- MT 72% tional AT is the most popular non-MT 0% 2010 2014 2014 2017 2017 technology in China, with a market All All Independent All Independent share of 33% in 2017. Among these, 6AT is most prevalent, accounting for Figure 4 Transmission types among passenger cars from independent manufacturers 25% of the market. CVTs account for in 2017 (left); transmission penetration trends of all manufacturers and independent 14% and DCTs, 12%. manufacturers from 2010 to 2017 (right) Among independent automakers, 100% adoption of ATs remains low rela- MT AT tive to that of joint ventures. In 2017, DCT MTs accounted for 72% of new sales 80% CVT by independents, as most of their AMT products were designed for mid- to 60% lower-end consumer groups (Figure 4). Of ATs sold by independent auto- makers, conventional ATs had the 40% highest market share, followed by DCTs and CVTs. 20%

Figure 4 also illustrates the market development of different transmis- 0% sion types in China. CVTs and DCTs BYD have seen a huge increase in market Chang’an Great WallDongfeng share from 2010 to 2017, with pen- SGM-Wuling -GM FAW Toyota SGM-Dongyue Beijing-Hyundai Chang`an-FordDongfeng-PSA etration of CVTs expanding faster Dongfeng- FAW Volkswagen Guangzhou-Honda than that of DCTs from 2014 to 2017. Shanghai Volkswagen Dongfeng-Yueda-KIA The development of CVTs and DCTs has been much slower in the inde- Figure 5 Transmission types by major manufacturers in 2014 pendent manufacturer fleet. DCTs were more widely deployed by inde- Adoption rates for advanced trans- parent manufacturers, such as DCT pendents, and the market share of missions are generally much higher from VW and CVT from Japanese CVTs decreased from 2014 to 2017. among joint ventures. In 2014, manufacturers. deployment of DCTs by FAW-VW Independent manufacturers that was 48%, and by Shanghai-VW, The design of MTs is simpler than explored ATs chose different devel- 39%. CVT penetration for Dongfeng- that of ATs, and domestic sup- opment strategies. In 2014, BYD Nissan was 46%, for FAW-Toyota, pliers lead the way in meeting MT adopted DCTs on 29% of its cars; 34%, and for Guangzhou-Honda, demand from independent manu- Dongfeng and Chery had a grow- 41% (Figure 5). This shows that the facturers. Because ATs are techni- ing share of CVTs, 15%-20%; and advanced transmission strategies of cally more complex, they are still Chang’an, Great Wall, and Geely joint ventures are likely to depend mainly imported or supplied by focused on developing ATs. on the technology decisions of foreign companies that produce in

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China. In 2015, around 95% of ATs in years, independent manufacturers or focused more on DCTs than CVTs. China came from foreign companies domestic suppliers began to develop Chang’an, Geely, and JAC have (Chen, 2016). According to customs the capacity to mass produce ATs. developed DCTs for some models. data, this percentage decreased to Chery is the only one on this list that 75% in 2017. Table 2 lists applications of advanced has put CVTs into production. There transmission technologies by some are some applications of AMTs on As the localization of foreign of the main manufacturers in China. small vehicles, such as those by JAC transmission suppliers is slow, inde- As highlighted by shading, a number and Haima. pendent manufacturers and domes- of ATs, DCTs, CVTs, and AMTs have tic suppliers have increased invest- been developed by domestic suppli- There are many collaborations ment in research and development of ers or independent manufacturers. between domestic suppliers and for- transmission technologies. In recent Among those, manufacturers have eign companies. These are listed in

Table 2 Transmission application by some main manufacturers in China.

Type Segment Model example Status Mass production (2013-) 6MT A/compact Small production (2016-) 800,000 units/year estimate 7DCT (W) 2.0T(B/SUV), 1.5T(A/B/SUV) Lynk 01 Geely (2017.12-) 7DCT Hybrid – Under development 300,000 units/year (2010-); 6AT B/SUV Boyue, Borui 600,000 units/year (2018-) 6MT 1.5T (compact SUV), 1.8L+ (G)/2.0L+ (D) G10, MG5, 350 Mass production 6DCT (W) A/B/SUV /950, MG6 etc. 600,000 units/year SAIC 7DCT (D) A0/A/SUV MG6 600,000 units/year 9AT SUV Chevrolet Equinox Mass production EDU2AT EV Roewe e550/ei6 etc. Mass production 7DCT A Viaggio, Mass production GAC 7DCT (W) – – Mass production estimate (2018.12-) 9AT Medium/large SUV Avancer 370T Mass production 6MT A/compact/compact SUV Yuexiang V7/Raeton etc. Mass production 5DCT (W) A Eado PHEV, XT etc. Mass production Chang’an 7DCT 1.5T, 1.8T – Mass production bidding 5AMT Small Yuexiang, Benben Mini etc. Mass production 6MT SUV , Tiggo etc. Mass production Chery CVT 1.6-2.0L 、, etc. 600,000 units/year 8AT SUV Jaguar Landover Mass production 5MT Compact/SUV , Foton etc. Mass production BAIC 6MT Compact Aumark S1, Ollin CTS, etc. Mass production 6MT Small/compact SUV Ruifeng S3 etc. Mass production 6DCT (F) Compact SUV Ruifeng S7, S3 etc. Mass production JAC 6DCT (R) MPV Ruifeng M6 etc. Mass production 5AMT Small Tongyue Mass production 6MT Compact H2, H5, H6 Mass production Great Wall 7DCT (W) Flat engine WEY VV5/WEY VV7 500,000 units BYD 6DCT (W) – S7 etc. Mass production JMC 8AT SUV X5, X7 200,000+ units Haima 5AMT Small Cupid Mass production

Note: Shaded transmissions are developed and produced by domestic suppliers or independent manufacturers; others are developed in partnership with foreign companies. (W)– Wet; (D) – Dry; (F) – Front; (R) – Rear

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Table 2 without shading. For exam- Table 3 Transmission types by major domestic suppliers ple, the 7DCT of Great Wall is the first 7-gear wet DCT in mass production Supplier Type Application Note Harbin DongAn in China. It is currently applied on the 1.2L (Turbo)-2.6L Automotive Engine 6-speed AT WEY VV5 and VV7 in 2017, two SUV (Turbo) Manufacturing models introduced by Great Wall. The transmission control unit, sensor 5-speed MT cluster unit, and application software Wanli 6-speed MT Transmission are supplied by Continental, and the CVT 1.6L-2.0L dual clutch module, by BorgWarner. Small to large cars, Besides the WEY models, Haval H2S, Punch Powertrain CVT SUV H6, and H7 will be equipped with Compact, MPV, SUV, this 7DCT. Application may further 5-speed MT expand into other models as pro- Zhuzhou Gear duction capacity increases (Gasgoo, 6-speed MT Compact SUV mini, small, compact, 2017). The 8ATs applied on JMC’s 5-speed MT Landwind X5 and X7 were developed MPV A/compact/compact by Shengrui Transmission Co. with 6-speed MT Chongqing SUV support from Ricardo. This front 8AT Qingshan Industry is 3.16% more efficient than 6ATs on 5-speed DCT(Wet) Compact the NEDC. Shengrui Transmission has 5-speed AMT Mini, small already achieved strategic coopera- tion with eight manufacturers on 18 Shuanglin 6-speed AT B/SUV models. These models will mate with Auto Parts 6-speed AT (Front) In development Shengrui’s second generation 8AT. Shengrui 8-speed AT SUV Table 3 shows the production capac- Transmission 13-speed AT B+ SUV/MPV estimate In development ity of major domestic transmission suppliers in China. The transmis- gearbox patents are already by leading global suppliers, has sion technologies listed in the table monopolized by big international just begun in China. companies like Aisin (Japan), ZF were mainly developed by domestic • The hydraulic torque converter Friedrichshafen AG (Germany), suppliers. These companies usually is a key part of ATs and CVTs, BorgWarner (USA), and Xtronic have long-term strategic coopera- but China’s design and manu- (Japan). This makes it challeng- tion pacts with manufacturers and facturing capacity for hydraulic continue to expand their business as ing for domestic technologies to torque converters needs to be production capacity grows. Some catch up. For example: improved. suppliers mainly focus on certain • The accuracy of gear teeth has a market segments. For example, • Transmission control units of significant influence on vehicle Chongqing Qingshan Industry pro- CVTs, ATs, and DCTs are still noise, vibration, and harsh- vides transmissions for more than mainly supplied by foreign ness (NVH) and durability. The 60% of mini cars. companies. current automatic gear teeth • The electromagnetic valve and As Table 3 highlights, there is a big are produced mostly by grind- sensor cluster unit of hydrau- gap between domestic and leading ing or honing. The accuracy lic pressure control systems global transmission technologies. of teeth grinding by domes- Three main reasons explain this gap: tic suppliers is one class lower are mainly supplied by foreign than that of the leading sup- companies. Domestic suppliers a. The lack of core transmission plier. The internal gear honing are conducting research and technology. Many automatic technique, which is widely used pilot production.

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• The steel belt and chain of 4 Further development elements—vehicle price and fuel CVTs are purchased from pathways cost—largely influence consumers’ foreign companies. There is purchase decisions, significantly In response to consumer demand no manufacturing capacity for more vehicles have been equipped and regulatory requirements, trans- these parts domestically. with DCTs among independent auto- missions for passenger cars in China • The development of lubricants makers in recent years because of are moving toward a wider spread for automatic transmissions is their lower cost. DCTs have higher of gear ratios, optimized shift logic, lagging. Most lubricants used improved transmission efficiency, transmission efficiency and a wide by manufacturers come from and lightweighting (Figure 6). application range, such as from 1.0L foreign companies. to 3.0L turbo. The technology is • The transmission brake system, Based on the trend from 2007 to 2017, applicable to most mainstream mod- which influences gear change MTs are likely to be further replaced els. Future market uncertainty comes performance, consists of a by ATs. However, MTs will still be the from the complexity of gear teeth number of stamped parts. mainstream transmission technology and technical challenges faced by Domestic suppliers do not have among independent manufacturers. domestic suppliers. Comparatively, complete capacity to manufac- This is first because independent the structure of CVTs is simpler and ture all the parts. manufacturers started late in devel- more cost-effective, making them oping automatic transmissions and more applicable on vehicles with are thus constrained by automatic b. High R&D cost and market risk. smaller engines and on models from transmission supply. In addition, they Investment in transmission devel- have a large low-end consumer base independent manufacturers. Conse- opment may not be proportion- quently, the uptake of CVTs is likely ally related to benefit. The devel- with vehicle prices targeted between to be faster among small cars. opment cycle of transmissions is 50,000 yuan and 150,000 yuan, mak- ing sales sensitive to price fluctuation. relative long compared with the Based on announced production usage cycle. For example, adding Comparing three major AT tech- plans and existing domestic capac- one more gear to a transmission nologies, traditional ATs have been ity, demand for ATs will exceed sup- would require redevelopment of the major option. As price-related ply over the next five years. both hardware and software. The new product may then lose mar- ket competitiveness if the devel- Regulatory requirement: Consumer demand: low-carbon, e cient, opment cycle gets prolonged comfortable, economical environmental by unforeseen challenges. Espe- cially for manufacturers that pro- duce a number models with lower production volumes, investment in transmissions may influence a Adopt advanced, ecient technologies company’s entire operation. c. A lack of basic experimental Wider gear ratio, Shift logic Improve transmission The development and pro- Lightweighting data. more gears optimization e ciency duction of advanced transmis- sion technology requires not only manufacturing capacity but also substantial testing data to cali- Smooth shift, economical Lower fuel consumption and emissions brate the product, which domes- tic producers don’t have. Figure 6 Demand for vehicle transmission development

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The technology of 6-speed ATs are rel- 100% atively mature, so ATs with more gears Others may gain market penetration on high- 90% MT end models. Besides 9ATs which have CVT 80% DCT already been applied on some models AT in China, 10ATs are planned for coming 70% Lexus and Ford/GM models in the U.S., 60% enabling both better performance and lower fuel consumption. As for DCTs, 50% FEV has already estimated the cost of 40% 8- and 10-speed DCTs, which implies their potential application in future 30% models (Isenstadt et al., 2016). In the 20% China vehicle market, AT penetration overall may not change significantly, 10% while the share of CVTs and DCTs will 0% increase as the technologies mature. 2010 2014 2017 2020E The uptake of ATs among independent automakers will most likely focus more Figure 7 Projection of transmission technology penetration by 2020 on DCTs while applying CVTs among the smaller vehicle segments. Figure 7 Domestically, Shanxi Keliyuan Crane DHTs use at least two sources of pro- shows the projected transmission Equipment Co. has developed an pulsion, an ICE and at least one elec- technology penetration among con- eCVT that is similar Toyota’s but with tric motor. Without either of these ventional vehicles by 2020. two planetary gear sets rather than sources, they are not fully func- just one. tional. Because DHTs have the elec- Under China’s electrification trend, tric motor fully integrated into the a variety of transmission strategies EDCTs offer electro-hydraulic control transmission, they are different from have been adopted or are under with a dual pump system that consists parallel hybrids where the electric development for hybrid and electric of a mechanical pump and an elec- motor is an add-on component to the vehicles. Among transmission con- tronic pump. DCTs in full hybrids are drive train. DHTs maintain a simple figurations for hybrids and plug-in being used by many OEMs. Porsche architecture and do not require an hybrid electric vehicles (PHEVs), the has already used an eDCT in the 918 additional launch element to switch most prevalent transmission configu- Spyder hybrid; Hyundai launched between modes. ration in China is parallel P2 mode. DCT-based full hybrids in 2016; and Globally, the Aisin/Toyota DHTs are The emerging technologies are VW has used one in the concept the most established in the market, electric CVTs (eCVTs), electric DCTs model of the CrossBlue Coupé Group (eDCTs), and dedicated hybrid trans- but an increasing number of manu- PHEV. In Europe, Getrag is offering missions (DHTs). facturers are developing their own OEMs a broader range of DCTs for DHTs. Another mass-produced DHT ECVTs do not use a belt or chain con- hybrids. In China, Shanghai Auto- is the Voltec II hybrid drive from GM nected to a pair of variable pulleys as mobile Gear Works introduced its used in the Chevrolet Volt and Malibu in conventional CVTs. Instead, eCVTs eDCT hybrid transmission at the 2017 Hybrid. In China, SAIC developed use an or generator to Shanghai International Automobile an electric drive unit that uses two control the speeds of planetary gear Industry Exhibition (SAGW, 2017). electric motors and a simple straight set components. ECVTs have been Volvo/Geely is known to be develop- gear transmission. Because the used on the Toyota Prius for years. ing a DCT-based hybrid system. transmission cannot operate without

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the electric motors, the system by energy recovery, and shorten efficiency improvements can trans- definition is a DHT. SAIC is applying electric driving range. late into greater vehicle range or a this system on the Roewe 550 and smaller battery pack. Two-gear AMTs • Safety: If acceleration is limited e950 PHEV. eliminate the clutch and directly con- at high speed, it may influence nect to the electric motor output overtaking and thus reduce Toyota, the first manufacturer to shaft. They use the speed change of driving safety. Most reducers bring full hybrids to market, initially the electric motor to switch gears. also do not have the parking offered products mated with either They are the preferred option by gear function as on conventional CVTs or DHTs but quickly deter- suppliers because of lower cost, vehicles. mined to use DHTs. In 2016, IHS higher efficiency, and greater stabil- estimated that DHTs accounted for • Reliability: Running the electric ity. However, gear switching comfort, 75% of transmissions motor at high RPM is challenging bump, and control present technical (Guile, 2016). As more and more for thermal management, NVH, challenges. Because of load torque major transmission suppliers develop and airtightness of the elec- limitations of CVTs and low efficiency DHTs, their adoption will continue to tric motor. To operate reducers and smaller gear ratio ranges of ATs, increase. IHS predicts that DHTs will at high speed, there are tough CVT and AT transmission pathways account for 50% of the hybrid fleet— requirements on gear teeth pro- are less popular than DCT and AMT and 5% of the entire fleet­—by 2028 cessing technology, bearing pathways. (Guile, 2016). life, and friction, wearing, and lubrication. It is estimated that multi-gear trans- For battery electric vehicles, every missions for EVs will improve driv- has a single-speed trans- Because of these limitations, multi- ing range by 8%-10% while improving mission, or reducer. Because elec- gear transmissions are important to performance. A two-gear transmis- tric motors have a much larger RPM improve energy efficiency and per- sion is the more feasible solution for range, makers of these vehicles usu- formance of electric vehicles. Inter- light-duty vehicles. ally pick a gear ratio that provides a nationally and domestically, devel- good compromise between accel- opment of multi-gear transmissions eration and top speed. Single-speed 5 Summary has mainly focused on existing AMT, transmissions have limitations on: DCT, AT, and CVT technologies used Figure 8 summarizes the key tech- on conventional vehicles. nologies discussed in this working • Drivability: One gear ratio cannot paper. The adoption status of each optimize vehicle performance Tesla tried to develop a 2-speed technology in China is indicated under all circumstances, includ- transmission but failed. Conse- before the name of each technology. ing acceleration at low speed, quently, Tesla applies a single-speed The pie chart is shown to reflect the high-speed overtaking, and gearbox on its Model S. The electric latest market penetration of com- climbing. Acceleration is weak motor of the BMW i8 drives the front mercialized technologies in China, at high-speed driving, especially wheels via a 2-speed automatic gear- with 5MT, 6AT, and CVT having rela- at speeds of 80 km/h or more, box. It always runs in first gear while tively higher shares. The start signs which influences drivability. in eDrive but switches to second gear represent emerging technologies • Efficiency: With a single gear in mixed modes (InsideEVs, 2015). that appear on a couple of models, ratio, the electric motor cannot such as 6MT, 9AT, AMT, and DHT. The perform in its most efficient zone Controlled by software, an eDCT green flags represent underdevel- under different driving condi- with two gears has all the bene- oped technologies that have been tions. This may increase energy fits of a conventional DCT but with applied or researched in other coun- consumption at high speeds, reduced weight, size, power loss, and tries but are still under development reduce the benefit of brake cost. The performance, design, and in China.

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The percentages following each technology summarizes its poten- tial for reducing fuel consumption. In most cases, the reduction poten- tial is compared with a designated baseline. The number represents an impact range considering the differ- ences in baseline vehicles’ segment, specifications, and other elements.

Based on the application status of transmission technologies in China, we group them into three categories:

Commercialized technologies. These are already adopted on at least several production models in Fuel efficiency / GHG reducing China and could be applied widely technologies through the fleet.

Emerging technologies. While available on passenger cars in the Chinese market, these have been adopted on only a couple of models, such as variants of flagship models or luxury vehicles that target at high- end users.

Underdeveloped technologies. Such Percentages in () are fuel consumption/GHG emission reduction potential technologies have been adopted in other markets but are not currently Figure 8 Advanced transmission technology map for passenger cars in China available on cars produced in China, or they have been announced by Table 4 Transmission technologies at different development stages in China manufacturers or suppliers and are likely to be adopted on production Commercialized cars in the near future. technologies Emerging technologies Underdeveloped technologies • 5/6MT • 8/9AT • 8DCT* Table 4 lists the transmission tech- • 5/6AT • AMT • eDCT, eCVT nologies under each category based • 6/7DCT • DHT • multi-gear transmission (EV) on our definition. This information will be used to estimate fuel-saving • CVT potential of all efficiency technolo- • Single reducer (EV) gies in the summary of this series of *8DCT is categorized as underdeveloped because it has been applied on only one luxury version of working papers. the Honda Spirior.

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References: Mazda. (2018). Skyactiv technology. Retrieved from http:// www.mazda.com/en/innovation/technology/skyactiv/ Chen, Y. (2016). 汽车自动变速器行业发展及展望(Vehicle automatic skyactiv-drive/ transmission industry development and future）. Auto Manu- facturing Engineer. 2016 No.12. Special Plan. DOI:10.16173/j. Ministry of Industry, Information, Technology (MIIT). (2015). cnki.ame.2016.12.007 Interpretation of “Made in China 2025”: promoting develop- ment of energy saving and new energy vehicles. Retrieved Great Wall ends transmission supply cooperation with Hyundai from http://www.miit.gov.cn/n973401/n1234620/n1234623/ Powertech. (2017, October 23). Gasgoo. Retrieved from c3843796/content.html http://autonews.gasgoo.com/china_news/70010865.html Shanghai Automobile Gear Works. (2017). SAGW Attends the Guile, C. (2016). The effect of vehicle electrification on transmis- 2017 Shanghai International Automobile Industry Exhibition sions and transmission market. CTI Mag. December 2016. with Innovative Products. Retrieved from http://en.sagw. Isenstadt, A., German, J. Burd, M., & Greif, E. (2016). Transmis- com/2017/0420/News/136.html sions. Retrieved from the International Council on Clean ZF: Multi-speed transmissions coming soon for Transportation https://www.theicct.org/publications/ electric cars. (2015, March 22). InsideEVs. transmissions Retreived from https://insideevs.com/ Jiang, C. Huang, W., Fang, W., & Xin J. (2014). Development of a zf-multi-speed-transmissions-coming-soon-electric-cars/ New Wet Dual Clutch Transmission and Driveline. SAE Inter- national. doi:10.4271/2014-01-1724

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