WORKING PAPER 2016-17

Transmissions

Authors: Aaron Isenstadt and John German (ICCT); Mark Burd and Ed Greif (Dana Corporation) Date: 29 August 2016 Keywords: Passenger , advanced , fuel-efficiency, innovation, , CVT, DCT, automatics

Introduction four to five years ago.2 The ICCT is col- in the rule and how they impact laborating with automotive suppliers on cost and benefits; In 2012, the U.S. Environmental a series of working papers evaluating Protection Agency (EPA) and the • Customer-acceptance issues, technology progress and new develop- Department of Transportation’s National such as real-world fuel economy, ments in , transmissions, Highway Traffic Safety Administration performance, drivability, reliability, body design and lightweighting, and (NHTSA) finalized a joint rule estab- and safety. other measures that have occurred lishing new greenhouse gas and fuel since then. Each paper will evaluate: This paper provides an analysis of economy standards for vehicles.1 The transmission technology development standards apply to new passenger • How the current rate of progress and trends. It is a joint collaboration and light-duty trucks, model years 2012 (costs, benefits, and market pen- between ICCT, BorgWarner, Dana, the through 2025. A mid-term review of the etration) compares to projections ITB Group, and FEV. The paper relies standards will be conducted in 2017. in the rule; on data from publicly available sources Assuming the fleet mix remains • Recent technology develop- and data and information from the par- unchanged, the standards require ments that were not considered ticipating automotive suppliers. these vehicles to meet an estimated Table 1. Transmission technology compared to EPA/NHTSA 2017-2025 rulemaking. combined average fuel economy of Rapid improvements in continuously variable transmissions and conventional 34.1 miles per gallon (mpg) in model automatics have compensated for slower than projected growth in the use of dual- year 2016, and 49.1 mpg in model clutch automated manual transmissions. year 2025. The standards require an Behind RM average improvement in fuel economy of about 4.1 percent per year. On schedule Manufacturing Efficiency Market Ahead of RM cost benefits penetration The technology assessments conducted by the agencies to inform Dual-clutch transmissions the 2017–2025 rule were conducted Conventional Automatics

Continuously variable transmissions

2 U.S. EPA & NHTSA. Joint Technical Support Document: Final Rulemaking for 2017-2025 BACKGROUND Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average As recently as 2007, 4- and 5-speed Fuel Economy Standards. Aug. 2012. Web. automatic transmissions (ATs) 1 US. EPA & NHTSA. EPA/NHTSA Final June 2016. https://www3.epa.gov/otaq/ dominated the vehicle market (>75% Rulemaking to Establish 2017 and Later climate/regs-light-duty.htm#2017-2025 U.S. Model Years Light-Duty Vehicle Greenhouse NHTSA. Corporate Average Fuel Economy share). Lock-up converters had Gas Emissions and Corporate Average Fuel for MY 2017-MY 2025 Passenger Cars and been widely used for over 20 years, but Economy Standards. Oct. 2012. Web. Jun. Light Trucks: Final Regulatory Impact otherwise transmission efficiency had 2016. https://www3.epa.gov/otaq/climate/ Analysis. Aug 2012. Accessed June 2016. regs-light-duty.htm#2017-2025 http://www.nhtsa.gov/fuel-economy not improved significantly for decades.

Acknowledgements: Thanks to Keith Martin from BorgWarner Transmission Systems, Sean Osborne and Joel Kopinsky from the ITB Group and Greg Kolwich and Kiran Govindswamy from FEV for their input and reviews.

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These pre-2007 4- and 5-speed ATs transmission, and offers the potential thus maximizes efficiency. The were significantly less efficient than for smooth/quick shifts without efficient engine operation can more manual transmissions, due to losses torque interruption. One issue with than offset the inefficiencies of the in the and in the the DCT is launch performance, as continuously variable transmission, hydraulic systems inside the transmis- the vehicle must start moving while especially during low-speed urban sion. Since 2007, advances in torque engaging a single clutch. Some manu- operation, and so produce overall converter lockup and hydraulics facturers use a wet hydraulic clutch to fuel consumption reductions. CVTs have improved so much that modern solve this problem, although the need were introduced in small volumes in automatics have significantly reduced for continuous lubrication from the the United States in 1989. However, the gap in efficiency—in some areas hydraulic system reduces efficiency the early designs suffered from eliminating it entirely. somewhat. By contrast, dry DCTs use limitations, which, in addition to high an accumulator and high-pressure friction losses, restricted torque to A major breakthrough in transmis- hydraulics, which are used to shut off such an extent that the transmission sion design was the development the hydraulic system. could only be used on smaller cars. of the Lepelletier gear set system. Recent improvements in CVT controls This system enables additional gear The other major transmission type and system design have reduced combinations without increasing the is the continuously variable trans- losses and expanded the torque number of clutches and gearsets. mission (CVT). Conventionally, this capacity and ratio coverage, making Six-speed Lepelletier automatics are design uses a belt or chain to connect the CVT another strong transmission usually slightly cheaper to manufac- two pairs of concentric cones, with competitor even for larger vehicles. turer than 4-speed ATs,3 and much infinitely variable ratios between cheaper than previously-designed the maximum and minimum points. Technology history 6-speed ATs. The additional number The efficiency of the transmission is of gear ratios and increased ratio reduced by friction losses related to According to the EPA fuel economy 4 spans improves efficiency and perfor- clamping forces on the belt/chain (as trends report, manufacturers have mance by: well as high-pressure hydraulics), but been rapidly increasing the number of the system allows the engine to always transmission gear ratios. Automatic • enabling the engine to operate run at optimal speed/load points and transmissions (AT) considered by in more efficient regions of the EPA in this report were divided into speed/load curve; 70% • allowing more torque multipli- 4-5 speed cation for vehicle launch, for 6 speed 60% better performance and engine downsizing; 50% • allowing lower engine rpm in top gear, for better efficiency and less engine noise. 40% Another important development in 30% the last ten years is the dual-clutch transmission (DCT). Introduced in the European Union in 2003 on the 20% Volkswagen DQ250, a DCT is essen- 8+ speed tially a manual (layshaft) transmis- 10% CVT non-hybrid sion with the odd-numbered gears 7 speed on one shaft and the even-numbered 0% gears on a second shaft. Each shaft             has its own clutch, and the gear on one shaft is disengaged at the same Figure 1. Historic market share of transmissions by number of ratios. (Source: U.S. EPA. time the gear on the other shaft is Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy engaged (see Figure 4). This design Trends: 1975 Through 2015. Dec 2015.) approaches the efficiency of a manual

4 US. EPA. Light-Duty Automotive 3 FEV. 2030 Passenger and Light Technology, Carbon Dioxide Emissions, and Commercial Vehicle Powertrain Technology Fuel Economy Trends: 1975 Through 2015. Analysis. Report commissioned by ICCT. Dec 2015. https://www3.epa.gov/otaq/ Forthcoming. fetrends-complete.htm

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Table 2. U.S. market penetration trends (cars and light trucks). (Source: U.S. EPA. Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends: 1975 Through 2015.)

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015* 4–5 speed 95.7% 93.3% 86.9% 76.6% 70.7% 63.4% 48.1% 32.9% 26.3% 18.2% 10.0% 6.1% 6 speed 3% 4.1% 8.8% 14.4% 19.4% 24.5% 38.1% 52.3% 56.3% 60.1% 58.4% 57.2% 7 speed 0.2% 0.2% 1.4% 1.5% 1.8% 2.5% 2.7% 3.1% 2.8% 2.8% 3.3% 2.7% 8+ speed — — — 0.2% 0.2% 0.1% 0.2% 1.7% 2.6% 4.1% 9.5% 13.2% CVT non-hybrid 0.7% 1.3% 1.4% 5.1% 5.5% 7.3% 7.2% 8.0% 9.2% 11.8% 16.6% 18.2% CVT hybrid 0.4% 1.0% 1.5% 2.1% 2.4% 2.1% 3.8% 2.0% 2.7% 2.9% 2.3% 2.5% Manual 6.8% 6.2% 6.5% 5.6% 5.2% 4.8% 3.8% 3.2% 3.6% 3.5% 2.8% 3.6% AT w/ lockup 91.8% 91.5% 90.6% 87.1% 86.8% 85.6% 84.1% 86.5% 83.4% 80.4% 76.7% 74.0% AT w/o lockup 0.3% 0.1% 0.0% 0.0% 0.2% 0.2% 1.2% 0.3% 1.1% 1.4% 1.6% 1.7%

* 2015 values are preliminary estimates. two groups: ATs with lockup torque report.) Assuming it is correct that adoption of CVTs in conventional converter (lockup bypasses the torque all 6+ speed ATs without lockup powertrains (i.e., non-hybrids). converter under certain conditions referenced in the trends report are to improve fuel economy) and ATs DCTs, then DCTs are about ~2% of the Manual transmissions (5+ gears) without lockup. Chrysler introduced transmission market in 2015. have remained between 3% and the first lockup torque converter in 4% of the market since 2010. the 1980s. By 2000, all automatics CVTs have seen a huge increase in Although the number of gear ratios had lockup capabilities. Thus, dual market share in the last three years: an has increased in both manuals and clutch transmissions (DCT) are likely estimated 22.6% of new, non-hybrid automatics, the rate of increase is the main example of automatic cars and 11.8% of non-hybrid trucks higher for automatics. transmission technology without were equipped with a CVT in 2015, about twice the market share in 2012. lockup reported in the trends report. Historical estimates of costs The share of planetary gear systems Unfortunately, EPA does not (yet) and benefits track DCT production, so the data used in Toyota and Ford hybrid gathered for the trends report did not vehicles, commonly referred to as The National Academy of Sciences separate DCT into a distinct category. electric CVTs (e-CVTs), has remained (NAS) 2002 report5 estimated that (EPA acknowledges that data incon- relatively constant between 2% and a 5-speed AT would see a 2%–3% sistencies for DCTs represent an area 3% since 2007. Thus, all of the growth fuel consumption reduction over a of future improvement in the trends in CVTs is attributable to increased 4-speed AT at a cost of $70–$154.

Table 3. Historical estimates of transmission technology costs and benefits as compared to the 2017-2025 rulemaking.

NAS 2002 NHTSA 2008–2011 EPA/NHTSA 2017–2025 BENEFIT COST BENEFIT COST BENEFIT COST Relative to 5-speed AT 2%–3% $70–$154 2%–3% $73–$160 1.1%–$1.6% $70 4-speed AT 6-speed AT 1%–$2% $140–280 1%–$2%, $146–291 0.7%–$0.8% ($81) 5-speed AT 8-speed AT — — 1%–$2% — 4.8%–$5.7% $47 6-speed AT Aggressive Shift Logic 1%–3% $0–$70 1%–3% $0–$70 5.1%–7.0% $22 No ASL DCT 3%–5% $70–$280 3%–5% $73–$291 5.7%–12.6% ($176)–$28 4-speed AT CVT 4%–8% $140–$350 4%–8% $146–$364 6.0%–8.7% — 4-speed AT Adv CVT 0%–2% $350–$840 0%–2% $364–874 — — CVT

NB: The agencies assumed that an 8-speed AT would only be applied to a 6-speed AT vehicle with towing requirement, all other vehicles transition from 6-speed DCT to 8-speed DCT. DCT effectiveness and cost estimates include both wet- and dry-clutch.

5 Transportation Research Board and National Research Council. Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards. Washington, DC: The National Academies Press, 2002. doi:10.17226/10172.

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More speeds continue the trend of would be additional benefits from EPA/NHTSA 2017–2025 greater efficiency: a 6-speed AT switching to a 7-speed or 8-speed AT. PROJECTIONS: MARKET will give 1%–2% fuel consumption PENETRATION, COSTS, benefit over a 5-speed AT. Since The rapid increase in computational AND BENEFITS this transmission was estimated to power in onboard computers and the In the agencies’ analyses, aggressive cost an additional $140–$280 and development of the Lepelletier gear shift logic (ASL) and early torque would require complex controls, NAS set has led to levels of transmission converter lockup (ETCL) were 2002 predicted 6-speed ATs in 2015 technology adoption well beyond combined in the models with to be limited to luxury/performance what was expected in 2002 and in automatic transmissions (“improved vehicles. As shown in Figure 1, today the 2008–2011 NHTSA rulemaking. control”— 6-speed ATs occupy more than For the 2017–2025 rulemaking, the IATC). The logic behind that 50% of the market, and 7-speed+ agencies estimated that dual-clutch decision was that their addition automatics and non-hybrid CVTs take automated manual transmissions requires only minor physical modi- up the next two largest shares. (DCTs/AMTs) and conventional ATs with more gears and aggressive shift fications and calibration software. CVTs were estimated to have 4%–8% logic (ASL) would both be relatively DCTs use clutches instead of torque fuel consumption reduction (relative to inexpensive: an 8-speed AT with ASL converters, and are thus considered a 4-speed AT) at a cost of $140–$350 would cost only $58 more than a automated manual transmissions. in NAS 2002, but would be limited conventional 4-speed AT for a 11% As such, only ASL is applied to DCTs by consumer acceptance issues and or more reduction in fuel consump- in the agencies’ models. production cost. Advanced CVTs, with tion. DCTs would be even cheaper The agencies used two levels of toroidal friction elements or cone-and- and more efficient than comparable ASL. Level 1, essentially downspeed- ring, were estimated to have 0%–2% ATs. EPA/NHTSA also considered ing, involves earlier upshift (i.e., benefit over a conventional (belt) CVT, consumer acceptance issues for at lower rpm during accelera- at a cost of $350–$480; these are able DCTs and CVTs. CVT driveability tion). Level 2 (“shift optimization”) to handle higher , essentially issues were expected to continue requires constant monitoring of all opening up heavier vehicle classes to to plague consumers, while the gear options and selecting the gear CVT implementation. agencies assumed that better control that puts the engine in the most algorithms would mostly eliminate 6 efficient operating zone. Level 2 For its 2008–2011 rulemaking, DCT consumer acceptance issues ASL is expected to come with driver NHTSA largely accepted the NAS and DCTs would replace CVTs and acceptability dilemmas—including 2002 report estimates without most ATs by 2025.7 change, although NHTSA found there shift busyness—despite the progress that is being made in making shifting smoother and less noticeable (e.g.,

Table 4. Rulemaking projected market share, costs, and benefits of considered transmission technologies

2025 Direct Fuel consumption 2021 2025 Manufacturing Cost reduction Relative to Aggressive shift logic — — $22 5.1%–7.0% no tech Early torque converter lockup — — $20 0.4%–0.5% no tech High efficiency gearbox 44% 95% $163 4.3%–5.7% no tech 6-speed AT 7% 0% -$11 1.7%–2.3% 4-speed AT 8-speed AT 30% 35% $47 4.8%–5.7% 6-speed AT 6-speed DCT 12% 0% -$176 (dry), -$124 (wet) 5.7%–8.1% 4-speed AT 8-speed DCT 42% 56% -$24 (dry), $28 (wet) 9.7%–12.6%* 4-speed AT 6-speed MT 5% 4% $173 2.0%–2.5% 5-speed MT CVT — — — 6.0%–8.7%** 4-speed AT

* 8-speed DCT shows a 3.9%–4.7% improvement over 6-speed DCT, and costs $153 more. **CVT benefit was calculated in EPA’s Lumped Parameter Model,7 and is not in the rulemaking.

7 “Lumped Parameter Model (LPM) for Light- 6 U.S. NHTSA. Light Truck Fuel Economy Duty Vehicles.” EPA OTAQ: Transportation Standard Rulemaking, MY 2008–2011. March and Climate. Feb 23, 2016. Accessed June 2006. Web. June 2016. http://www.nhtsa. 2016. https://www3.epa.gov/otaq/climate/ gov/fuel-economy lpm.htm

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through more available gears). The much so that they project 6-speed today some wet-clutch DCTs have agencies assumed that suppliers can ATs will be virtually eliminated by mostly overcome this problem with minimize these issues by MY 2017, 2025 (although 6-speed MTs are on-demand hydraulic systems). It was and they noted that if the problems projected to maintain a 4% market also assumed that, because there is persist, effectiveness may be lower share in 2025). no torque converter, DCTs would and costs may be higher. The Level likely be paired with engines with 2 ASL fuel consumption reduction is The effectiveness of a 6-speed AT is high low-speed torque or with trans- relative to a transmission without any relative to a 4-speed AT, and incorpo- missions that have shorter gear ratios previously implemented ASL. Level 2 rates a 7% improvement in gearbox to match the torque multiplication of ASL is expected to improve efficiency efficiency that would accompany a a torque converter. over Level 1 by 4%–5%, at virtually no switch to 6-speed AT. An 8-speed AT additional cost. was applied after 6-speed AT only to Despite improvements in automatic vehicles with towing requirements transmission and dual-clutch trans- Locking the torque converter in (minivans, midsize and large trucks). mission efficiency, the agencies ATs (and CVTs) eliminates slip to The reported effectiveness of an consider manual transmissions to improve fuel economy. However, 8-speed is relative to a 6-speed. exhibit the most efficient energy at lower vehicle speeds, torsional Relative to a 4-speed AT, an 8-speed transfer due to low internal gear energy is harder to dampen, and it AT shows 6.5%–7.8% reduction in losses, minimal hydraulics, and can create shaking or shuddering fuel consumption. actuation energy input from the as it passes through the vehicle. driver. Of course, the driver may not Thus, early torque converter lockup The incremental direct manufac- select the optimum gear for best fuel (ETCL) and partial lockup require turing cost (DMC) for 8-speed ATs economy, so on the official test cycles upgraded materials to withstand from 6-speed is $47. Note that the advanced automatic transmissions higher loads. For the rulemaking, agencies predict a net savings of $11 usually provide better fuel economy. “early lockup” is considered to occur in switching from the older 4-speed at lower speeds than conventional design to a 6-speed Lepelletier AT. More gear ratios (usually lockup strategies. As before, driver Thus, switching from a 4-speed to an gears) permit the engine to operate acceptability (driveability, noise, 8-speed AT results in a DMC of $36. in the optimum efficiency range more vibration and harshness) is key to often. However, proper stepping of Vehicles with no towing requirement successful implementation. the ratios is important to driver sat- were modeled as having an 8-speed isfaction and acceptability. For the DCT after a 6-speed DCT. The Reduction of mechanical friction 2017–2025 rulemaking, the agencies effectiveness of 8-speed DCTs drives the improvements in gearbox assumed the number of gear ratios over 4-speed ATs is 9.7 12.6%, efficiency. A number of strategies are %– increases from 5 to 6 in manual trans- and 5.7%–8.1% for 6-speed DCTs available for reducing gearbox friction, missions. For reference, 6-speed and over 4-speed ATs. Note that in the and all are generally applicable to 5-speed manuals (MT) are estimated 2011 Ricardo study cited in the any type of transmission. The fuel to occupy 2.78% and 0.76% of the rulemaking, the effectiveness values consumption reduction of a high market, respectively, in 2015. efficiency gearbox (HEG) compared include high efficiency gearbox. to a baseline AT is 4.3%–5.7% (lower Independent of other improvements Lastly, neither agency felt that CVTs bound due to 4WD trucks with an in transmission, DCTs were estimated would be competitive within the unimproved rear ). to have 4%–6% improvement over 2017–2025 timeframe. Nevertheless, ATs with same number of gear ratios. the Lumped Parameter Model Increased numbers of gears also The agencies further split DCTs into (LPM, EPA’s model for effectiveness increase the transmission friction, wet-clutch and dry-clutch versions. of various vehicle technologies) costs, and weight. Thus, increasing Wet-clutch DCTs have higher torque estimated CVT effectiveness as the number of gears may see dimin- capacity since the clutches are 6.0%–8.7%, relative to a 4-speed AT. ishing returns. Furthermore, as cooled and hydraulically actuated. is common for many transmission Wet clutches are also useful in Figure 2 combines the historical technologies, increased shifting can vehicles with low-torque engines, market share from the FE Trends lead to consumer acceptance issues where cooling is required to allow Report with projected market shares (perceived shift busyness) as well as the clutch to be slipped over a of various transmissions from the additional losses (due to shifting). longer period of time. The agencies EPA/NHTSA 2017–2025 rulemaking The agencies expect 8-speed ATs to assumed that the hydraulic pump for 2021 and 2025 (identified by the be readily available beginning in MY leads to reduced efficiency compared dotted lines). As indicated by the 2017 and widespread by MY 2025, so to dry-clutch DCTs (although yellow region in the lower left of

WORKING PAPER 2016-17 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 5 TRANSMISSIONS

the figure, 4 speed transmissions 100% (both manual and automatic) have other 90% CVT been virtually phased out by 2015. eCVT

Similarly, 5-speed transmissions 80% 5-speed 7-speed (red) are losing market share and manual automatic 8-speed+ 70% DCT are estimated to taper off to zero by 2021. Future projections are for e 60% 5-speed 6-speed 8-speed+ATs and, especially, DCTs automatic 50% automatic to dominate the market, with CVTs et Shar tapering off to zero by 2021. 40%

Mark 6-speed manual 8-speed+ 30% automatic CURRENT PRODUCTION COSTS 20% 4-speed automatic AND BENEFITS ESTIMATES 6-speed DCT Since the rulemaking was written 10% in 2012, numerous developments 0% have occurred in CVTs, DCTs,                and conventional automatics. Model Year Several of these developments are described below. Figure 2. Market share of various transmissions by speed (color) and type (shade). CVT = continuously variable transmission for non-hybrid cars and trucks. eCVT = CVT continuously variable transmission. DCT = dual clutch transmission. (Source: US. EPA. Light-Duty Automotive Technology, Carbon Dioxide Emissions, and The typical CVT utilizes a belt Fuel Economy Trends: 1975 Through 2015. Dec 2015.) sandwiched between pairs of cones: essentially two variable-diameter pulleys (Figure 3). Historically, torque limitations hindered the adoption of CVTs in all but the smallest vehicles. HIGH GEAR But improvements in belt design have dramatically increased the torque capabilities of CVTs up to 450Nm.8 CVTs captured an estimated 18% of DRIVEN PULLEY the entire market in 2015 and sales include compact cars (1.0L to 1.8L) V-BELT/PUSHBELT all the way through large passenger vehicles (>2.5L)9 including the DRIVE PULLEY ELEMENT Nissan Murano—a midsize crossover RING BUNDLE/ SUV with a 3.5L engine. PACK

As an example of the improve- ments, Jatco produces a CVT for LOW GEAR small cars that has an increased RING gear spread, which enhances launch and acceleration. It couples a small

Figure 3. Typical belt-driven CVT configuration (left), and typical belt design (right).11 8 “Pushbelt (Working Principle).” Bosch Transmission Technology B.V. Accessed June 2016. http://www.bosch.nl/ “sub-transmission” to the CVT. This the efficiency benefits from reduced transmission_technology/en/html/5869. “sub-transmission” is an auxiliary weight and the increased gear htm “Bosch Pushbelt – Efficiency on the gearbox. Complexity is increased, spread, internal friction is reduced Road.” Bosch Mobility Solutions. Video 10 accessed June 2016. https://www.youtube. but the overall size is reduced by by 30%. com/watch?v=bwKKGdU0fjU 10% and weight by 13%. In addition to 9 As but one example of several CVT suppliers, Jatco offers CVTs suitable for a range of vehicle sizes. “Product 10 “Jatco CVT7.” Jatco Product Information. Information.” Jatco. Accessed June 2016. http://www.jatco.co.jp/ENGLISH/products/ http://www.jatco.co.jp/ENGLISH/products/ cvt/cvt7.html. Accessed June 2016.

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DCT11 CLUTCHES 1 & 2 6TH REVERSE 5TH As shown in Figure 4, a DCT includes two clutches, one for each concentric input shaft (orange, purple). The two output shafts (countershafts, hidden) each have a number of gears (blue- gray) that can spin freely around their respective output shaft. Gear selectors (smooth gray) axially slide on the output shafts to select a specific gear and connect it to its output shaft, thereby driving the output shaft. Only OUTER SHAFT one clutch is engaged at a time, so that only one of the countershafts drives the final output (largest gray INNER SHAFT gear). However, the gear selectors can 1ST preselect gears in order to shift faster 4TH without any torque interruption. That 3RD GEAR 2ND is, while one clutch and gear selector SELECTOR are engaged in a particular gear, a Figure 4. Typical DCT layout and operation. second gear selector on the non-driv- ing countershaft (corresponding to conventional 5-speed AT). The torque DCT packaging is a concern, the un-clutched input shaft) engages converter improves launch behavior especially as the number of gears the next gear. The shift occurs when and acceleration through torque increases. Odd-number-geared DCTs the first engaged clutch disengages multiplication, but additional costs, may be easier to produce (due to and the previously disengaged clutch complexity, length, and reduced the necessity of a reverse gear). engages. Basic animations of DCT efficiency come with it. However, the Several 7-speed DCTs are already on operation are widely available.12 cost of the clutches for a DCT can the market, and their market share be high, thus the torque converter is expected to grow. For example, Since DCTs represent a class of does not make the transmission sig- Hyundai now includes a 7-speed automated manual transmissions, nificantly more expensive. dry-clutch DCT option for all its they typically do not use a torque Sonata, Elantra, and Tuscon models.16 converter, as with conventional Today, wet-clutch DCTs approach automatics. This elimination leads to the efficiency of dry clutches due to In a report commissioned by the launch issues. One option to solve this the expanded use of an on-demand ICCT, currently in final draft form,17 problem is to simply include a torque hydraulic pump.15 DCTs have also seen FEV estimated the incremental cost converter.13 Honda uses one between improvements in clutches and trans- of a 10-speed wet-clutch DCT trans- the engine and an 8-speed DCT on the mission fluids, mainly by optimized mission over a 7-speed or 8-speed baseline 2015 2.4-L Acura TLX.14 The friction materials and clutch pressure conventional automatic would be DCT+torque converter combination control. These developments allow $156. Based on the total costs listed is designed to improve the launch of micro-slip of the clutches, which in the report, the incremental cost the DCT, and achieves a 7.4% decrease permits reduced system pressure and of a 10-speed wet-clutch DCT over in fuel consumption (compared to a lower fuel consumption. a 7-speed dry-clutch DCT is around $110. Thus, FEV’s estimated incremen- Wet-clutch DCTs are also useful tal cost of a dry-clutch DCT over a 11 U.S. Patent 5167587 & U.S. Patent 7846049 for cooling the clutch in conditions comparable automatic transmission is 12 Thomas Schwenke. “Dual-Clutch where the clutch is slipped longer approximately $46. This cost increase Transmission / Double-Clutch Gearbox for low-drag torque. Under these (Animation).” YouTube. May 7, 2014. https:// is higher than that estimated for the www.youtube.com/watch?v=t-oULh0I3iA. conditions, dry-clutch DCTs would 2025 rulemaking, which was actually Accessed June 2016. simply burn out. a cost reduction of $8–$165 for 13 Robinette, D., Skrzycke, T., “A Dual Clutch Torque Converter for Dual Input Shaft Transmissions,” SAE Int. J. Engines, April 8, 15 Matthew Beecham. “Q&A with BorgWarner: 16 Fuel Economy. U.S. EPA OTAQ. http://www. 2013. doi:10.4271/2013-01-0232 Dual clutch transmissions.” Just Auto fueleconomy.gov. Accessed June 2016. 14 Dan Carney. “Honda’s new 8-speed DCT News & Analysis. Jan. 22, 2013. http:// 17 FEV. 2030 Passenger Car and Light uses a torque converter.” Automotive www.just-auto.com/interview/dual-clutch- Commercial Vehicle Powertrain Technology Engineering. Aug. 6, 2014. http://articles. transmissions_id130903.aspx. Accessed Analysis. Draft: Sept. 2015. Forthcoming sae.org/13432/. Accessed June 2016. June 2016. report for ICCT.

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wet-clutch and dry-clutch DCTs over Table 5. Comparison of estimated costs from rulemaking and suppliers. Source: EPA/ their conventional AT counterparts. NHTSA 2017-2025 rulemaking, FEV 2015, and FEV/EPA 201322

Cost Estimates FEV estimated the incremental cost of a dual wet-clutch alone over a dual TECHNOLOGY BASELINE RULEMAKING FEV dry-clutch would be $44, which is 6-speed dry-clutch DCT 6-speed AT -$127 to $26 (NAS) — essentially on par with the estimated 7-speed dry-clutch DCT 7-/8-speed AT — $46 cost in the rulemaking of $52. Note 10-speed wet DCT 8-speed AT — $156 that FEV estimated a 10-speed DCT 8-speed wet-clutch DCT 6-speed wet-clutch DCT $153 $161* would cost only $66 more than a 10-speed wet-clutch DCT 7-speed wet-clutch DCT — $66 7-speed DCT. This is because FEV assumed 10 gear steps would be Wet-clutch (DCT) Dry-clutch (DCT) $52 $44 realized by applying an advanced 8-speed AT 6-speed AT $47 $54* connection scheme of gear 6-speed MT 5-speed MT $173 $40 and synchronization units, a concept *Costs extracted from FEV/EPA 2013 report on advanced 8-speed transmissions and reduced by different from typical DCT layouts that manufacturer learning trends as applied in the final rulemaking. tries to solve some of the packaging issues of 7-speed+ DCTs (albeit only gearsets are also nested to save The 9-speed ZF automatic consumes for front- drive vehicles).18 space, leading to smaller and lighter 16% less fuel than a 6 speed automatic transmissions for the same number at the same driving speed. One Upgrading a 6-speed manual to a of gears compared to DCTs. Thus, the innovation is that this 9-speed uses 7-speed dry-clutch DCT decreased number of gear ratios in conventional interlocking, splined dog clutches fuel consumption by 4.1%–7.9% on automatics is increasing rapidly, up to (rather than friction clutches) to the smaller vehicle classes modeled 10 in the upcoming Lexus application achieve faster and more efficient by FEV. Unfortunately, the addition and Ford/GM transmission, enabling torque transfer.23 Splined dog clutches of advanced stop/start functions both higher performance and lower have lower spin losses on clutches and weight reduction to all other fuel consumption than the 8-speed that are not engaged. DCT modeling prevents a separate automatic transmissions modeled in assessment of the efficiency benefit the rulemaking.20 And, due to some Ongoing research on better friction of DCT over conventional automatics. consumer dissatisfaction issues with materials has improved clutch some of the initial DCTs sold in the performance and reduced friction 24 Conventional Automatics market (discussed more below), losses, leading to decreased fuel 25 many OEMs are focusing on improved consumption. The groove patterns Conventional automatic transmissions automatic transmissions.2122 and material in the clutch friction have also been undergoing incremen- plates are engineered to reduce tal improvements. Unlike conventional drag, which, in addition to improving DCTs, which must add gears for 20 Sean Szymkowski. “General Motors fuel economy, provides seamless each expansion, the Lepelletier gear will introduct 10-speed automatic on shifts for better performance and set design allows easier expansion eight vehicles by 2018.” GM Authority. Mar. 16, 2016. http://gmauthority.com/ delivers durability that improves the of the number of gear ratios. For blog/2016/03/general-motors-will- life of the transmission. example, a 9-speed automatic made introduce-10-speed-automatic-on-eight- by ZF Friedrichshafen AG (and used vehicles-by-2018/. Accessed June 2016. 21 David Sedgwick. “Once-promising dual- by Chrysler, Jaguar Land Rover and clutch transmissions lose favor in U.S.” Honda) uses 4 simple planetary Automotive News. Dec 7, 2015. http:// 23 “9-speed Automatic Transmission.” gearsets and 6 shift elements.19 The www.autonews.com/article/20151207/ ZF Technology for Cars: Automatic OEM06/312079988/once-promising-dual- Transmission. http://www.zf.com/corporate/ clutch-transmissions-lose-favor-in-u.s. en_de/products/product_range/cars/ 18 Govindswamy, K., Hellenbroich, G. and Accessed June 2016. cars_9_speed_automatic_transmission. Ruschhaupt, J., “7-XDCT: Compact and 22 U.S. NHTSA. Corporate Average Fuel shtml. Accessed June 2016. Cost-Efficient Dual Clutch Transmission Economy for MY 2017-MY 2025 Passenger 24 Merkel, H. “Development Trends of Friction for Small and Mid-Size Vehicles,” SAE Int. Cars and Light Trucks: Final Regulatory Products”. BorgWarner Transmission J. Passeng. Cars - Mech. Syst. 6(2):2013, Impact Analysis.. Aug 2012. Accessed June Systems. CTI Symposium. December 2013. doi: 10.4271/2013-01-1271. “10-Speed Dual 2016. http://www.nhtsa.gov/fuel-economy. 25 “BorgWarner Delivers Advanced Clutch Transmission.” FEV North America, FEV. 2030 Passenger Car and Light Technologies For New GM 8-Speed Inc. https://www.youtube.com/watch?v=p_ Commercial Vehicle Powertrain Technology Transmission.” PR Newswire. Sep 21, cBBRY7qhg. Video accessed June 2016. Analysis. Draft: Sept. 2015. Forthcoming 2015. http://www.prnewswire.com/news- 19 Dan Carney. “Honda’s new 8-speed DCT report for ICCT. U.S. EPA. Light-Duty releases/borgwarner-delivers-advanced- uses a torque converter.” Automotive Vehicle Technology Cost Analysis, Advanced technologies-for-new-gm-8-speed- Engineering. Aug. 6, 2014. http://articles. 8-Speed Transmissions: Revised Final transmission-300145826.html. Accessed sae.org/13432/. Accessed June 2016. Report. FEV. April 2013. EPA-420-R-13-007. June 2016.

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Leakage from hydraulic pumps and valves is also a major source of trans- mission energy loss. Consequently, there is a concerted effort among suppliers and OEMs to improve hydraulics (especially in combination with start-stop).26

IMPROVEMENTS IN

DEVELOPMENT rp1 > rp2 rp1 = rp2 rp1 < rp2 Underdrive 1:1 Overdrive DCT Figure 5: Cross section diagram showing planetary ball tilt angle determining drive ratio. DCTs may be ideally suited for hybrid and applications (as in the VW Jetta Hybrid and the 2017 Hyundai Ioniq). The can provide assist during launch, eliminat- ing the starting clutch and allowing simpler clutches and lower cooling requirements.27 Several companies continue to make incremental improvements in DCTs.28

VariGlide planetary variator29 VariGlide planetary variator technology is a compact traction drive Figure 6: The VariGlide planetary variator employs elasto-hydrodynamic lubrication that employs rotating planets that can (EHL) to transfer torque. The components and ball clamping features in the ring be tilted on their axes to smoothly are shown on the right. and continuously vary the drive ratio. As shown in figure 5, by changing changes, and therefore the speed This of torque transfer is the angle of tilt of each planet’s axis ratio may be continuously varied as also known as elasto-hydrodyamic of rotation, the contact radii ratio the transmission is shifted through the lubrication (EHL).30 At the traction ratio range. contact there are losses that include 26 Reduced system pressure, electrohydraulic slip, side-slip and spin. Variable pumps (Getrag), variable mechanical It is similar to a dual-ring planetary gear clamping force is provided by simple pumps (ZF), bi-pressure pumps (GM, Aisin/ set, but the planets in the VariGlide Toyota), and low leak solenoid valves are mechanical ball , which enable some of the many approaches to reducing planetary variator are spherical rollers the correct amount of clamping force transmission leakage. (standard bearing technology), which for the given load without the need 27 Matthew Beecham. “Q&A with BorgWarner: transfer load through traction rather Dual clutch transmissions.” Just Auto for active control. News & Analysis. Jan. 22, 2013. http:// than gear teeth. The carrier allows the www.just-auto.com/interview/dual-clutch- planets to rotate about their tilting While the production capability has transmissions_id130903.aspx. Accessed yet to be proven, the design has a June 2016. axes and find their equilibrium. The number of potential benefits over 28 Ernest DeVincent. “GETRAG DCT New input and output power are delivered Modular Platform: From 100Nm to on the same centerline (as opposed to belt CVTs. It uses roller bearings 500Nm.” Getrag. Presentation given at instead of a belt to transmit loads, th spur gears), and like a planetary gear, 7 International CTI Symposium May which should be more durable. These 2013, Detroit. http://www.getrag.com/ the drive can be used to power-split media/products/powershift/7dct300/ or power-sum. bearings also eliminate the need for Presentation_7DCT300.pdf “Efficient a high-pressure pump, which con- Transmissions.” Getrag Transmission tributes to some of the benefits over Technology. 2016. http://www.getrag.com/ As a traction drive, it transmits en/technology/transmission_technology/ forces between the rolling surfaces pleasure_and_consumption/efficiency_ (between ring and planet ball 30 Fern Thomassy. An Engineering Approach and_dynamics_1.html to Simulating Traction EHL. CVT-Hybrid 29 This is a relatively new concept that operates contacts) through resistance to International Conference Mecc/Maastricht/ differently than current production CVTs. shearing of a thin film of traction fluid. The Netherlands, Nov. 17–19, 2010.

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belt CVTs.31 The planetary CVT can 12% 11.61% handle higher torque than belt CVTs FTP NEDC WLTC and the same design can be used in 10.56% both FWD and RWD applications. 10% 7.98% s.The VariGlide has some similarities 8% 7.83% to the (virtually extinct) toroidal/ 6.38% 5.91% roller CVT, in that both use a 6% 5.85% traction fluid, rather than friction, to transmit torque.32 Used by Nissan 4% (“Extroid CVT”) in the 1990s on 3.19% 3.32% several passenger cars and currently 2% produced by Torotrak33 for use on heavy duty vehicles, toroidal CVTs have largely stalled in development 0% City Highway Combined for light-duty vehicles. The VariGlide has some of the same potential issues Figure 7. Fuel economy comparison with 6-speed AT tied to the need for traction fluid, such as spin losses and traction fluid electrification, transmissions are also CONSUMER ACCEPTANCE ISSUES upgrading to handle these changes. durability. According to Dana, traction Consumer acceptance issues must be Not only are hydraulic systems fluids have shown significant improve- considered for any new or improving changing to adapt to more engine ments in both durability (resistance vehicle technology. Transmissions, in starting and stopping (discussed to degradation) and overall traction particular, suffer from these issues, above), auxiliary pumps are also coefficient. They continue to work since they directly affect how the being developed. For example, FEV with their OEM partners to jointly engine sounds and how the vehicle sees an integrated electric motor as develop specifications that will feels. DCTs and CVTs generally an option on their 7-speed+ DCTs.36 ultimately meet the expected “fill have much more pronounced issues for life” expectations.34 The core than improved automatics. But technology has also been subjected Manual transmissions automatics also have some issues, to 70,000 hours of durability testing, Manual transmissions, too, may use primarily gear “hunting” when the which shows robustness against slip- electric clutches for reducing fuel number of gears increases. 35 induced damage. consumption and increased comfort. A system by Schaeffler can reduce The transmissions with more gear Electrification fuel consumption by 3.1% (idling the ratios and wider gear spread have major positives in addition to better As manufacturers roll out increasing engine when coasting in the highest fuel economy: lower gears improve numbers of vehicles equipped with gear) to 8.2% (stopping the engine vehicle launch, a lower ratio for the start-stop (shutting of the engine when coasting) at a direct manufac- top gear provides quieter operation instead of idling while stopped or turing cost of $112. This system enables on the highway, and more gears coasting) and further levels of coasting start-stop for manual trans- misions; idling the engine or stopping can better maintain both lower rpm it entirely depending on the degree for better fuel economy and higher 37 rpm for faster acceleration. These 31 “VariGlide ® CVT Efficiency.” Dana Holding of savings. Corporation. June 21, 2016. https://www. advantages have contributed to the youtube.com/watch?v=N34pxHDoGO4&fea rapid adoption of more gear ratios in ture=youtu.be. Video accessed June 2016. recent years. 32 “Extroid CVT.” Nissan’s CVT Technologies. http://www.nissan-global.com/PDF/tcvt_e. pdf. Accessed June 2016. DCTs and CVTs have the potential for 33 “Torotrak.” Torotrak Group Products. http:// even better efficiency than ATs, but www.torotrak.com/products-partners/ 36 “10-Speed Dual Clutch Transmission.” FEV some early models of DCTs and CVTs products/torotraktransmissions/. Accessed North America, Inc. https://www.youtube. have been criticized for poor shift June 2016. com/watch?v=p_cBBRY7qhg. Video 34 Written comment received from Dana on accessed June 2016. quality and a different “feel,” respec- June 29, 2016. 37 Luca Ciferri. “Schaeffler touts fuel- tively, from what customers expect. 35 Dana claims over 70,000 hours of savings e-clutch for manual gearboxes.” component durability testing for the Automotive News. June 6, 2016. http:// DCTs are losing favor with some VariGlide. “VariGlide ® CVT Testing.” Dana www.autonews.com/article/20160606/ Holding Corporation. June 21, 2016. https:// OEM10/306069990/schaeffler-touts-fuel- manufacturers, largely due to abrupt www.youtube.com/watch?v=DZeJ1kUiEHg&f saving--e-clutch-for-manual-gearboxes. shifting and lurching on many initial eature=youtu.be. Video accessed June 2016. Accessed June 2016.

10 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2016-17 TRANSMISSIONS

DCT applications. For example, the Some manufacturers—primarily with high-pressure pumps and friction, first DCT used on the Ford Focus Nissan, Honda, Toyota, and offering net efficiency improvements. was criticized for abrupt shifts, shift Subaru—are avoiding the calibra- The CVT is an inherently lower cost “busyness,” and poor launch.38 Poor tion challenges and perceived shift design and suppliers have managed calibration and gear ratio selection “busyness” associated with many to keep costs low enough so that likely explain much of these early DCTs by switching to CVTs. However, CVT sales are increasing rapidly. challenges facing DCTs. Indeed, there CVTs also come with their share of Continued incremental development are examples of DCTs that have been criticism. CVTs have been derided for will further reduce losses and cost. widely praised, e.g. the 2015 VW the exact opposite behavior as DCTs. Golf,39 which suggests that part of With no “shifting,” CVTs can appear There is no doubt that CVTs suffer the problem is not the hardware but as constantly revving (or constantly greater losses than DCTs and con- software controls that are not yet not revving), with engine speed ventional ATs. Their eventual cost and sophisticated enough. However, it seemingly uncorrelated to accel- market share, especially compared may not be possible to remove all of erator pedal input, as consumers are to DCTs, depends on the degree to the shift shock with dry-clutch DCTs, accustomed to. Again, calibration is which these losses are minimized and as the high temperature variations partly at fault for this issue, but this the rate of improvement in DCTs (cost make it difficult to control clutch effect may simply take a bit of getting and consumer acceptance). engagement. And even wet-clutch used to. For example, Consumer New “planetary” CVTs,42 which use DCTs may never launch like a con- Reports recently praised the CVT traction fluid, show promise, although ventional hydraulic automatic used in the 2016 Honda Accord. This they have yet to be introduced at transmission, as they are, fundamen- evaluation suggests, again, that the a commercial scale. Their relatively tally, manual transmissions shifted primary problem is not the hardware, simple design, compared to belt- automatically. DCTs are popular in but software controls. New shifting driven CVTs, could also mean they Europe, as manual transmissions have logic attempts to recreate some of are, overall, less expensive to manu- a high market share in Europe and the shifting experience of driving facture. However, as with all traction- customers are used to the launch an automatic on a CVT.41 Indeed, drive transmissions, at the traction quality of a , improved drivability acceptance of contact there are losses that include but this familiarity is not the case in CVTs is reflected in the doubling of slip, side-slip and spin. Improvements the United States. Manufacturers are market share since 2012 to over 1 in are being made to traction fluid testing different options based on 10 trucks and 1 in 5 cars (Figure 1 and durability and assuring “fill for life” is their expertise: those with manual Table 2). a prerequisite for market acceptance. transmission experience (primarily European-based manufacturers) are DISCUSSION implementing DCTs, with or without DCT torque converters. Other improve- CVT DCTs have not taken off in the United ments are also coming to DCTs, States as forecast due to consumer such as electro-mechanical clutch After years of slow development, acceptance issues and difficulty in many of the solutions to problems actuation (rather than hydraulic).40 packaging.43 Furthermore, due to associated with CVTs have reached temperature constraints, it may not a point where CVTs are now a real 38 David Sedgwick. “Once-promising dual- be possible to solve the consumer alternative to traditional automatics. clutch transmissions lose favor in U.S.” acceptance issues with dry-clutch Automotive News. Dec 7, 2015. http:// Increased hydraulic pressure and DCTs. Wet-clutch DCTs are becoming www.autonews.com/article/20151207/ improved belts vastly expanded the OEM06/312079988/once-promising-dual- more efficient than predicted, torque range of CVTs. The engine clutch-transmissions-lose-favor-in-u-s. approaching the efficiency of some Accessed June 2016. efficiency benefits possible with CVTs dry-clutch DCTs, and they benefit 39 Mark Rechtin. “Volkswagen Golf, Ford finally offsets the losses associated F-150 win car, truck of the year awards.” from reduced temperature issues Consumer Reports. Jan 12, 2015. http:// compared to dry-clutch DCTs. Better www.consumerreports.org/cro/ 41 Lindsay Chappell. “Nissan tweaks CVTs news/2015/01/volkswagen-golf-ford-f- to be less CVT-like.” Automotive News. 150-win-car-truck-of-the-year-awards- July 13, 2014. http://www.autonews.com/ detroit-nactoy/index.htm. Accessed June article/20140713/OEM03/307149936/ 2016. VW Golf Consumer Reports’ Road nissan-tweaks-cvts-to-be-less-cvt-like. 42 McIndoe, G., VanSelous, J., Liu, T., and Test. Consumer Reports. http://www. Accessed June 2016. Keith Griffin. “Why David, J., “Efficiency Analysis of Multi-Mode consumerreports.org/cro/volkswagen-golf- do today’s transmissions have so many Passenger Car Transmission Concepts road-test.htm gears?” U.S. News & World Report. July 16, Featuring a VariGlide® CVT,” SAE Technical 40 Liu, F., Chen, L., Yao, J., Zhang, J. et al., “A 2015. http://usnews.rankingsandreviews. Paper 2016-01-1108, 2016, doi:10.4271/2016- New Clutch Actuation System for Dry DCT,” com/cars-trucks/best-cars-blog/2015/07/ 01-1108. SAE Technical Paper 2015-01-1118, 2015, Why_do_Todays_Transmissions_Have_so_ 43 According to BorgWarner, packaging issues doi:10.4271/2015-01-1118. Many_Gears/. Accessed June 2016. are mainly due to the DCTs increased girth.

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control logic will also improve the the small car segments, due to their improvements to CVTs and ATs, DCTs lurch and launch problems.44 low cost.46 are unlikely to largely replace CVTs and ATs in the 2025 time frame, as The need to add a wet clutch adds Changes since agency projected by EPA/NHTSA in the $52 to the cost according to agency evaluations were conducted 2017-25 rulemaking. James Verrier, estimates ($56 according to a recent for 2017–2025 rulemaking CEO of BorgWarner, thinks the DCT 45 FEV analysis ), and degrades fuel future in the United States “will be It appears that manufacturers may economy. The efficiency improve- primarily the wet DCT for higher be sticking to the transmissions they ments to the wet clutch reduce torque applications,” such as diesels know best. Most vehicles in Europe the efficiency penalty, but at some and gasoline turbocharged engines.47 additional (un-quantified) cost. still use manual transmissions. DCTs, which are simply manual transmis- FEV’s recent cost assessment Some, if not all, of the DCT shortfall sions shifted automatically, are suggests that DCTs may be more will be replaced by improvements to widely used by European manufac- expensive than assumed by the CVTs and conventional automatics. turers in the United States, and their agencies in the rulemaking, although Newer CVTs have reduced internal customers seem to be accepting still cheaper compared to conven- friction, wider ratio spread, and them. CVT transmissions are tional automatics. increased torque capacity. They will extremely popular in Japan, as they likely be strong competitors to DCTs excel in the low-speed congested Conventional AT and conventional ATs through at conditions that dominate driving in least 2025, especially for manufac- Some OEMs (particularly in North Japan. Japanese manufacturers used turers with extensive CVT expertise. America) are sticking to designs they to use conventional automatics in Conventional automatics can add have experience with and relying on the United States, due to the higher additional gear ratios in a relatively higher-speed ATs rather than DCTs performance and torque require- inexpensive manner and maintain a and CVTs. Incremental improvements ments and the better fuel economy compact size. Recent improvements in these higher-speed automatics of conventional automatics on the are increasing efficiency, such as have led to efficiencies roughly on highway. However, as CVTs have improved clutch designs and the par with what the agencies predicted. improved to handle higher torque use of splined dog clutches, and ATs However, 9- and 10-speed automatics and expand the ratio spread for largely avoid consumer acceptance have already been introduced in better highway fuel economy, the issues. They are likely to maintain a the market, which have incremental Japanese manufacturers have largely larger share of the market in 2025 efficiency improvements over the replaced conventional automatics than projected in the rulemaking. 8-speed transmission modeled for with CVTs in the United States. The the rulemaking. In addition, friction U.S. manufacturers are experimenting clutches can be replaced with with both CVTs and DCTs, but early SUMMARY mechanical clutches, as on the new ZF customer acceptance issues appears In their technology analyses for the 9-speed transmission, although that to be pushing them back onto their 2025 rulemaking, EPA and NHTSA requires faster on-board computers traditional expertise with conven- projected that DCTs would overtake to better calibrate shifting. tional automatics. Both manufactur- conventional automatics by 2021 ing history and consumer history with and continue to increase market The agencies projected in the the feel of a torque converter favor rulemaking that 8-speed ATs would share through 2025. However, due conventional automatics for the U.S. to numerous consumer acceptance completely replace 6-speed ATs manufacturers. by 2025. However, BorgWarner issues (which may be due primarily to calibration, rather than the actual believes it is likely that 6-speed ATs DCTs will certainly have a significant hardware), their sales have not will continue to be used for at least share of the future transmission reached levels indicative of such a market. However they will cost more transition. While some of the technical than estimated in the rulemaking, challenges faced by DCTs are being they may not be quite as efficient solved, the solutions will likely make due to the need for a wet clutch or 44 Cho, D., Gupta, R., Dai, E., McCallum, J. et a torque converter, and they will al., “Launch Performance Optimization of never shift quite like a conventional 47 Richard Truett. “Ford gets the PowerShift GTDI-DCT Powertrain,” SAE Int. J.Engines dual clutch transmission right, but is it too 8(3):2015, doi:10.4271/2015-01-1111. hydraulic automatic. Combined with late?” Automotive News. January 5, 2016. 45 FEV. 2030 Passenger Car and Light https://www.autonews.com/article/20160105/ Commercial Vehicle Powertrain Technology BLOG06/301059997/ford-gets-the- Analysis. Draft: Sept. 2015. Forthcoming 46 Personal from BorgWarner powershift-dual-clutch-transmission-right- report for ICCT. to ICCT, received on June 16, 2016, via email. but-is-it. Accessed June 2016.

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them slightly more expensive and share for higher speed automatics is agencies did not explicitly predict slightly less efficient than projected strong, putting ATs on track to meet the costs or benefits of CVTs in the by the agencies. Although DCTs projections, and possibly to help fill in rulemaking, CVTs today appear to remain an attractive option in terms the gap left by lagging DCTs. be on track to match the benefit of comparative cost-effectiveness estimates available in EPA’s lumped and efficiency, they are unlikely to When the rulemaking analyses were parameter model and they cost less match the penetration estimates in conducted four to five years ago, than conventional automatics. the rulemaking. CVTs were not projected to be a com- petitive option by 2025. However, While the VariGlide® Planetary Conventional automatics, in general, years of incremental improve- Variator was not considered in the are matching the predicted cost ments have shown that CVTs can, overall assessments in this paper, if it and likely exceeding the projected and are, a good alternative trans- proves successful it may offer another benefit, due to the introduction of 9- mission. Market share has grown bump in efficiency, reduced cost, and and 10-speed transmissions and the rapidly since 2012 and consumer improved durability. increased efficiency of mechanical/ acceptance issues no longer seem dog clutches. The growth in market to be plaguing CVTs. Although the

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