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WORKING PAPER 2018-15
Fuel-efficiency technology trend
assessment for LDVs in China:
Transmission technology
Authors: Zifei Yang, Yong Chen, Aaron Isenstadt
Date: 17 September 2018
Keywords: transmission technology, fuel efficiency, passenger car
1 Background Fuel efficiency
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.
ef fectiveness , 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
likely to use in China by 2030. This • A d et a i l e d l ite r atu re s u r vey,
fleet efficiency target of 4 L/100 km
information enables a more accurate, including both Chinese and
for passenger cars, a 20% decrease
China-specific understanding of future global regulator y documents,
from the 2020 target of 5 L/100 km. In
technology pathways. of f i ci a l a n n o u n ce m e nt s , a n d
the Technology Roadmap for Energy
industry and academic reports.
Saving and New Energy Vehicles
We group technologies into sev- • Analysis of databases from Polk
published by the Society of Automo-
eral categories: advanced engine, and Segment Y.
tive Engineers of China (SAE China,
transmission, vehicle technologies,
2016), a 2030 fleet efficiency target • Conversations with manufactur-
thermal management, and hybrids and
of 3.2 L/100 km was set. To evaluate ers, tier one suppliers, research
electrification (Figure 1). The specific
whether and how these targets can be entities, and domestic and inter-
technologies we considered include
met, it is essential to understand what national experts.
those that are available today and
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 ef fectiveness 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).
© INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION, 2018 WWW.THEICCT.ORGFUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
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%
B ecause of lower costs and f uel
c o n s u m p ti o n , m a n u a l t r a n s m i s- 0%
sions (MTs) have been the main- 2007 2008 2010 2011 2012 2013 2014 2015 2016 2017
stream technology for decades in
Figure 2 Market penetration of manual and automatic transmissions in China,
China. However, MTs’ leading market
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 rati o s . T h e ef f i c i e n c y of th e
• Dual-clutch transmissions
of MTs has decreased from a peak transmission is reduced by fric-
(DCTs) consist of two separate
of more than 70% in 2009 to 39% tional losses related to clamp-
manual transmissions with odd-
in 2017 (Figure 2). Today, automatic i n g fo rce s o n th e b e lt /c h a i n
numbered gears on one shaf t
transmissions account for the major- as well as the need for high-
and even-numbered gears on a
ity of new vehicle sales. pressure hydraulics. However,
second shaft. Each shaft has its
own clutch, and the gear on one the system produces an infinite
The automatic transmission (AT )
shaft is disengaged at the same number of engine/wheel speed
market is split among several types
time that the gear on the other ratios, allowing the engine to
in China:
shaf t 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. m ov i n g w h i l e e n g a g i n g o n e 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 Europe.
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.
2 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2018-15FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
Ta ble 1 sh ows f u e l - co nsu m ptio n Table 1 Projected benefits and costs of considered transmission technologies
b e n ef it s a n d cos t s fo r dif fe re nt
Fuel-consumption Direct manufacturing
transmission technologies based on reduction cost (CNY*)
estimates by the U.S. National High-
U.S.
way Traffic Safety Administration U.S. China China
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)
A s Ta ble 1 sh ows , D C Ts te n d to 8-speed DCT** 9.7%–12.6% 4-speed AT
-179 (wet)
exhibit higher cost- ef fectiveness
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 converter lockup
0.4%–0.5% 128
converter lockup
energy than automatics , but ATs
High-efficiency No high-efficiency
select the optimum gear ratio at all 4.3%–5.7% 1043
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%
M o s t ATs a n d C V Ts to d ay h ave
adopted torque converter lockup
AT 8AT 3%
to reduce fuel consumption by low- 33%
MT
e rin g th e loss of p owe r tra n sfe r 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%
the lockup is usually triggered at 14%
7DCT 9%
h ig h e r s p e e d s . At l owe r ve h i cl e 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
th ro u g h th e ve h icl e . T h u s , e a rly Ate nza is m ate d with a 6 -sp e e d A c c o r d i n g to Ta b l e 1 , ATs w i t h
torque conver ter 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, G erman , ex p a n d s th e l o c k u p r a n g e f ro m ciency compared with conventional
Burd, and Greif, 2016). Only a few 64% on current 5ATs to 89% over ATs witho ut A S L . A S L increases
models enable lockup at lower t h e N e w E u r o p e a n D r i ve C y c l e efficiency through downspeeding,
spe e ds . For exa m ple , th e M azda (NEDC) (Mazda, 2018). which enables earlier upshif t—at
WORKING PAPER 2018-15 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 3FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
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% 0%
tional AT is the most popular non-MT
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% MT
adoption of ATs remains low rela-
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%
D
n
gf ll
C g
ry
ly
en
D jing u n
gf Hy ng
i
an
on Do `a -GM
g- ng rd
FA ed SA
G GM To IA
zh ng a
-H e
da
sion types in China. CVTs and DCTs Y
Sh g-N da
on a
ng Do ot
ou yu
’a
-W e
en
B
ee
he
en fe o
S W -K
W
C ang iss
ag
M ag
on
li
u -P
ng
en un
y
gf ng n-F
G
ng ai
a
have seen a huge increase in market
w
w
at
ha
h
ks
ks
re
C
on -
D
ol
ol
G
share from 2010 to 2017, with pen-
-
Y
SG
V
V
ha
ei
W
ai
etration of CVTs expanding faster
B
gh
ua
FA
an
than that of DCTs from 2014 to 2017.
Sh
D
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 CV T from Japanese
CVTs decreased from 2014 to 2017. a m o n g j o i n t ve n t u r e s . I n 2 0 1 4 , manufacturers.
deployment of DCTs by FAW-V W
Independent manufac turers that wa s 4 8 % , a n d by S h a n g h a i -V W, The design of MTs is simpler than
explored ATs chose different devel- 39%. CVT penetration for Dongfeng- t h a t o f ATs , a n d d o m e s ti c s u p -
opment strategies . In 2014 , BY D Nissan was 46% , for FAW-Toyota, pliers lead the way in meeting MT
adopted DCTs on 29% of its cars; 3 4% , and for G uangzhou- H onda , 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 CV Ts , 15%-20%; and advanced transmission strategies of cally more complex, they are still
Chang ’an , G reat Wall, and G eely joint ventures are likely to depend m a i n ly i m p o r te d o r s u p p l i e d by
focused on developing ATs. o n t h e te c h n o l o g y d e c i s i o n s o f foreign companies that produce in
4 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2018-15FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
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 C h a n g ’a n , G e e l y, a n d JAC h ave
(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- The re 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 Emgrand
Small production (2016-)
800,000 units/year estimate
Geely 7DCT (W) 2.0T(B/SUV), 1.5T(A/B/SUV) Lynk 01
(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) Maxus G10, MG5, Roewe 350 Mass production
6DCT (W) A/B/SUV Roewe 550/950, 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, Trumpchi 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 Riich, Tiggo etc. Mass production
Chery CVT 1.6-2.0L Chery A3、Chery E5, etc. 600,000 units/year
8AT SUV Jaguar Landover Mass production
5MT Compact/SUV Senova, 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 Haval 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 Landwind 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
WORKING PAPER 2018-15 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 5FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
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
in China. It is currently applied on the Harbin DongAn
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 Zhejiang Wanli 6-speed MT
Transmission
are supplied by Continental, and the CVT 1.6L-2.0L
dual clutch module, by BorgWarner.
Besides the WEY models, Haval H2S, Small to large cars,
Punch Powertrain CVT
SUV
H6, and H7 will be equipped with
Compact, MPV, SUV,
this 7DCT. Application may further 5-speed MT
Zhuzhou Gear minivan
expand into other models as pro-
duction capacity increases (Gasgoo, 6-speed MT Compact SUV
2017). The 8ATs applied on JMC’s mini, small, compact,
5-speed MT
Landwind X5 and X7 were developed MPV
by Shengrui Transmission Co. with A/compact/compact
Chongqing 6-speed MT
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 Ningbo 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
Transmission 13-speed AT B+ SUV/MPV estimate In development
Table 3 shows the production capac-
ity of major domestic transmission
suppliers in China . The transmis- g e a r b ox p ate nt s a re a l re a d y by leading global suppliers, has
sion technologies listed in the table monopolized by big international just begun in China.
were mainly developed by domestic companies like Aisin (Japan), ZF
• The hydraulic torque converter
suppliers. These companies usually Friedrichshafen AG (Germany),
is a key part of ATs and CVTs,
have long-term strategic coopera- BorgWarner (USA), and Xtronic
but China’s design and manu-
tion pacts with manufacturers and (Japan). This makes it challeng-
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 • Transmission control units of
m a r ke t s e g m e n t s . Fo r exa m p l e ,
significant influence on vehicle CVTs, ATs, and DCTs are still
Chongqing Qingshan Industry pro-
noise, vibration , and harsh- m a i n ly su p p li e d by fo re ig n
vides transmissions for more than
ness (NVH) and durability. The
60% of mini cars. companies.
current automatic gear teeth
are produced mostly by grind- • The electromagnetic valve and
As Table 3 highlights, there is a big
ing or honing. The accuracy sensor cluster unit of hydrau-
gap between domestic and leading
of teeth grinding by domes- lic pressure control systems
global transmission technologies.
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
t e c h n o l o g y. M a ny a uto m ati c technique, which is widely used pilot production.
6 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2018-15FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
• The steel belt and chain of 4 Further development elem ent s—vehicle price and f uel
C V Ts a r e p u r c h a s e d f r o m cost—largely influence consumers’
pathways
foreign companies . There is purchase decisions , signific antly
no manufacturing capacity for In response to consumer demand
more vehicles have been equipped
these parts domestically. and regulatory requirements, trans-
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 transmission efficiency and a wide
improved transmission ef ficiency,
by manufacturers come from application range, such as from 1.0L
and lightweighting (Figure 6).
foreign companies. to 3 .0 L 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
p e r fo r m a n ce , co n sis t s 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- independent manufacturers. Conse-
have a large low-end consumer base
opment may not be proportion- quently, the uptake of CVTs is likely
ally related to benefit. The devel- with vehicle prices targeted between
50,000 yuan and 150,000 yuan, mak- to be faster among small cars.
opment cycle of transmissions is
relative long compared with the ing sales sensitive to price fluctuation.
B ased on announced produc tion
usage cycle. For example, adding plans and existing domestic capac-
Comparing three major AT tech-
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- Consumer demand:
Regulatory requirement:
opment cycle gets prolonged low-carbon, efficient,
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, efficient technologies
company’s entire operation.
c. A lack of basic experimental
Wider gear ratio, Shift logic Improve transmission
data. The development and pro- Lightweighting
more gears optimization efficiency
duction of advanced transmis-
sion technology requires not only
manufacturing capacity but also
Smooth shift, economical Lower fuel consumption and emissions
substantial testing data to cali-
brate the product, which domes-
tic producers don’t have. Figure 6 Demand for vehicle transmission development
WORKING PAPER 2018-15 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 7FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
The technology of 6-speed ATs are rel-
100% Others
atively mature, so ATs with more gears
may gain market penetration on high- 90% MT
CVT
end models. Besides 9ATs which have
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 f ully f unc-
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
T h e e m e r g i n g te c h n o l o g i e s a r e Globally, the Aisin/Toyota DHTs are
V W has used one in the concept
electric CVTs (eCVTs), electric DCTs the most established in the market,
model of the CrossBlue Coupé Group
(eDCTs), and dedicated hybrid trans- but an increasing number of manu-
PHEV. In Europe, Getrag is offering facturers are developing their own
missions (DHTs).
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 electric motor 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
8 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2018-15FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
the electric motors, the system by energy recover y, 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
Toyota, the first manufacturer to ove r t a k i n g a n d t h u s r e d u c e
shaft. They use the speed change of
bring full hybrids to market, initially driving safety. Most reducers
the electric motor to switch gears.
offered products mated with either also do not have the parking
They are the preferred option by
CV Ts or DHTs but quickly deter- gear function as on conventional
suppliers because of lower cost,
mined to use D HTs . In 201 6 , I H S vehicles.
higher efficiency, and greater stabil-
estimated that DHTs accounted for • Reliability: Running the electric ity. However, gear switching comfort,
75% of hybrid vehicle transmissions motor at high RPM is challenging bump, and control present technical
(G uile, 201 6). As more and more for thermal management, NVH, challenges. Because of load torque
major transmission suppliers develop and air tightn ess of th e 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 ce s s i n g te c h n o l o g y, b e a r i n g 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-
electric car 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: Figure 8 summarizes the key tech-
DCT, AT, and CVT technologies used
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 indic ated
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
h i g h - s p e e d ove r t a k i n g , a n d
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 sof tware, an eDC T 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
re d u c e th e b e n e f i t o f b r a ke cost. The performance, design, and in China.
WORKING PAPER 2018-15 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 9FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
Th e p e rce nt a g e s fo llowin g e a ch
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
Fuel efficiency /
least several production models in 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
• CVT
will be used to estimate fuel-saving
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.
10 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2018-15FUEL-EFFICIENCY TECHNOLOGY TREND ASSESSMENT FOR LDVS IN CHINA: TRANSMISSION TECHNOLOGY
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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