PRELIMINARY DESIGN OF NEW CONCEPT COMPACT CONTINUOUSLY
VARIABLE TRANSMISSION
LAU ONG YEE
A project report submitted in partial
fulfillment of the requirement for the award of the
Degree of Master of Mechanical Engineering
Faculty of Mechanical and Manufacturing Engineering
Universiti Tun Hussein Onn Malaysia
JANUARY 2014
v
ABSTRACT
Continuous Variable Transmission (CVT) system provides a solution that enable the
generation of staples shifting of gear ratio regardless of the speed and torque
requirement. CVT technology had been available since century ago, and it become
popular among the luxury car. However, due to the certain limitation of current CVT
design, CVT are not popular among the machineries. In this paper, Autodesk Inventor
was used to develop a new concept of compact CVT with simple and compact.
According to David G. Ullman, there are five steps in design process which start with
determine of problems, planning, develop design requirement, evaluation, decision, and
lastly communication of the result. Selection of the design had been going thru several
processes such as House of Quality (HoQ), and development of Engineering Design
Specification (EDS). In order to finalize the design, morphological chart with weighted
rating method had been used. New concept of compact CVT that had been developed is
less complicated compare to existing CVT system. In this new concept of compact CVT,
two unit of curved surface cones are used. One unit of idler located between two cone
act as rotation transmitter in this compact CVT. In addition, multiplication of the gear
ratio can be achieved by using multiple cone concepts.
vi
ABSTRAK
Kewujudan sistem tansmisi boleh laras berterusan(CVT) telah menjadikan perubahan
gear lebih lancar tanpa mengira kelajuan dan tork yang diperlukan. Teknologi ini telah
wujud beberapa dekad yang lalu, dan kini ia telah menjadi popular di antara kenderaan
mewah. Walau bagaimanapun, disebabkan oleh batasan yang ada pada sistem tranmisi
boleh laras, ia masih tidah popular di antara mesin. Dalam kajian ini, perisian Autodesk
Inventor akan digunakan untuk membangunakn konsep baru CVT yang bersaiz padat
dengan mekanisma yang ringkas. Merujuk kepada David G. Ullman, terdapat lima
langkah dalam proses merekabentuk bermula dengan penentuan masalah, perancangan,
pembangunan keperluan rekabentuk, penilaian, keputusan dan terakhir sekali ialah
mengkomunikasi data atau keputusan. Dalam proses pemilihan rekabentuk perlu ada
beberapa langkah yang penting iaitu House of Quality (HoQ), dan pembangunan
spesifikasi kejuruteraan(EDS). Untuk mendapatkan keputusan terakhir penilaian
rekabentuk , carta morfologi dengan gabungan kaedah pemberat digunakan. Konsep
baru CVT padat ini telah dibangunkan dan ia adalah lebih ringkas dari segi struktur
binaan jika dibandingkan dengan rekabentuk yang sedia ada. Dalam rekabentuk CVT
baru ini, 2 unit kon dengan permukaan berlengkung digunakan. Manakala 1 unit idler
diletakkan di antara 2 unit kon berkenaan sebagain penghantar kuasa putaran. Tambahan
pula, pendaraban kuasa boleh diaplikasikan dalam konsep baru ini untuk menghasilkan
tork yang lebih tinggi.
vii
CONTENTS
TITLE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
CONTENT
vii
LIST OF FIGURE
x
LIST OF TABLE
xii
LIST OF SYMBOLS ANF ABBREVIATIONS
xiii
LIST OF APPENDICES
xiv
CHAPTER 1 INTRODUCTION
1 1.1 Introduction
1 1.2 Background study
3 1.3 Problem Statement
4 1.4 Objective
4 1.5 Scope of Study
4 1.6 Project Significance
5 CHAPTER 2 LITERATURE REVIEW
6 2.1 Fundamental of CVT
2.1.1 Belt-pulley CVT
6 8 viii
2.1.2 Toroidal CVT
10 2.1.3 Cone based CVT
11 2.2 13 CVT patent
2.2.1 Patent 1 – Continuously Variable Transmission (EP
Pat No. 0639732A1)
14 2.2.2 Patent 2 – Continuously variable transmISSION
(US PAT NO. 5324239)
15 2.2.3 Patent 3 – Friction type continuously variable
transmISSION (US PAT NO. 5746676)
17 2.2.4 Patent 4 – Continuously variable transmISSION
2.3 (US PAT NO. 5888160)
18 Available CVT Product
19 2.3.1 Nissan Xtronic
19 2.3.2 Nissan Extroid
21 2.3.3 Audi Multitronic
22 2.3.4 Warko CVT
23 2.3.5 Comparison
24 CHAPTER 3 METHODOLOGY
25 3.1 Introduction
25 3.2 Project Method
26 3.3 Project Flow Chart
27 3.4 Project Gantt Chart
28 CHAPTER 4 RESULT AND DISCUSSION
29 4.1 Introduction
29 4.2 Formulation
29 4.2.1 House of quality (HoS)
30 4.2.2 Engineering design specification(EDS)
31 4.3 33 Concept design
4.3.1 Clarifying functional requirement
33 ix
4.3.1.1 Activity analysis
33 4.3.1.2 Product component decomposition
34 4.3.1.3 Product function decomposition
35 4.3.2 Generating alternative concepts
36 4.3.3 Concept Selection
37 4.4 39 Concept Development
4.4.1 Cone
40 4.4.2 Idler
40 4.4.3 Controlling device
41 4.4.4 Casing
42 4.5 42 Generation of Concept
4.5.1 Design Concept 1
42 4.5.2 Design Concept 2
43 4.5.3 Design Concept 3
44 4.5.4 Design Concept 4
44 4.6 45 Modeling and Design Development
4.6.1 Transmission mechanism
45 4.6.2 Adjusting Mechanism
46 4.6.3 Full Assembly of Compact CVT
48 4.6.4 Double Cones Gear ratio
49 4.6.5 Multiple Cones Concept
50 4.7 51 Gear Ratio
CHAPTER 5 CONCLUSION
55 5.1 Introduction
55 5.2 Recommendation
56 5.3 Conclusion
56 REFERENCES
APPENDIX
57
x
LIST OF FIGURE
1.1
Clutch engagement and disengagement
1
1.2
Punch Powertrain VT2 CVT gearbox
3
2.1
Comparison
of
RPM
performance
between
Manual Transmission (MT) with Continuous
Variable Transmission (CVT)
7
2.2
Belt-pulley CVT operations
8
2.3
Arrangement of Metal V-belt on CVT drive: (a)
basic configuration ; (b) Metal v- belt structure
9
2.4
Nissan Toroidal CVT
10
2.5
Mechanism of Toroidal CVT in overdrive mode
(left) and low gear mode (right)
11
2.6
Concept of using cones ring CVT
12
2.7
Open KRG transmission
12
2.8
Warko's CVT
13
2.9
CVT patent EP0639732A1
15
2.10
Position of the steel bands
16
2.11
Steel bands arrangement
16
2.12
Double cone friction CVT
17
2.13
Schematics view of continuously variable transmission
18
3.1
Project flow chart
27
3.2
Project Gantt chart
28
4.1
House of quality for the new concept of CVT
31
xi
4.2
Product component decomposition for CVT
35
4.3
Product function decomposition for CVT
36
4.4
Cone with curved surface
40
4.5
Concept of idler
41
4.6
Design concept 1
43
4.7
Design concept 2
43
4.8
Design concept 3
44
4.9
Design concept 4
45
4.10
Pair of cones in the opposite direction
46
4.11
Idler attached to the holder which controls the gear ratio
47
4.12
Complete assembly of the compact CVT
48
4.13
Arrangement of basic double cone concept of CVT
49
4.14
Multiple cones concept
50
4.15
Illustration of idler moving path
51
4.16
Relationship between gear ratio and position of the idler
52
4.17
Relationship between gear ratio and diameter of cones
52
4.18
Arrangement of idler position in multiple cones design
53
4.19
Control of the gear shifting with the movement of
Idler 1 and Idler 2
54
xii
LIST OF TABLE
2.1
Nissan Xtronic
20 2.2
Nissan Extroid
21 2.3
Audi Multitronic
22 2.4
Warko CVT
23 2.5
Comparison of CVT products
24 4.1
Engineering design specification for CVT
32 4.2
Activity analysis for CVT
34 4.3
Morphological matrix
36 4.4
Alternative designs combinations
37 4.5
Rating ordinal scale
38 4.6
Weighted rating of CVT
38 4.7
Weighted rating of power transmitter
39 xiii
LIST OF SYMBOLS AND ABBREVIATIONS
MOHE
-
Ministry of Higher Education
CVT
-
Continuously Variable Transmission
EDS
-
Engineering Design Specification
HoQ
-
House of Quality
QFD
-
Quality function development
R
-
Double cones maximum ratio
C
-
Numbers of cone
xiv
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Full assemble of new concept compact CVT
61
B
Cone in new concept compact CVT
62
C
Idler with holder in new concept compact CVT
63
D
Floating cone continuously variable transmission
64
E
Cone pulley v-belt continuously variable
Transmission
73
F
Cone and idler continuously variable transmission
78
G
Friction type continuously variable transmission
91
1
CHAPTER 1
INTRODUCTION
1.1
Introduction
At the early century when cars become popular among the people, manual transmission
system was introduced. For manual transmission system, drivers need to disengage the
clutch (refer Figure 1.1) to disconnect the power from the engine and then continue with
changing gear ratio. However, this method becomes a challenge for new driver and they
need some period of the time to get used of it.
Figure 1.1: Clutch engagement and disengagement [1]
2
Research and development process had been carried out by the automotive
industries expert to ease the problem by inventing other types of the transmission system
which named as automatic transmission system. Fluid coupling and torque converter
was used to replace the clutch system and planetary gears uses to perform gear change in
automatic transmission. Compared to the manual transmission, invention of automatic
transmission has gradually made the driving car much easier. However, complicated
gear structure had indirectly increased the weight and price of the car. After automatic
transmission, semi-automatic transmission had been introduced in the market but was
not popular in automotive industries because of the price and under development
technology.
Blooming of the economy and automotive technology had brought continuously
variable transmission (CVT) to the surface. At an early stage, CVT technology was
limited in low powered machinery such as scooters. Development of the materials
technology and high tech machinery, people had found their way to implemented CVT
technology in motorcar, and it was successfully increasing the efficiency of power
transmission.
Continuously variable transmission is a type of the transmission system that
widely used in automobile industries. Compare to the conventional automatic
transmission, CVT provides more useable power, better fuel economy and smoother
driving experience. All this advantages should be credit to special features of CVT such
as gear system that does not use any tooth and ability to create infinite numbers of gear
ratio.
With discovered of new material technology, the CVT system had gradually
replaced the conventional transmission system due to it high efficiency and smooth gear
shift.
3
1.2
Background study
Now days, CVT can be found on most automotive industries such as scooter, tractor and
also modern cars. All those benefits from CVT had attracted automotive developer
including Nissan and Toyota from moving their path to CVT development. Because of
CVT system does not need gear changing, it's to be benefits for those using CVT cars
which able to maximize the efficiency of the engine all the time during driving.
Figure 1.2: Punch Powertrain VT2 CVT gearbox [2]
Over the decades, lots of research had been done on CVT, and there are
successful products that already available in the market such as metal pushing belt CVT.
Many CVT designs that still need on going research and development process had been
patented on the different country as well.
4
1.3
Problem Statement
Technology development in automotive industries had started promoting CVT to
modern car. With various type of testing, it is proven that CVT may overcome the
burden of changing gears in toothed gear system. Although CVT had been introduced in
the market almost 10 years ago, they are still costly and only widely apply in the modern
car such as the hybrid car. Usage of electric CVT in Toyota Prius may directly improve
driving quality and fuel consumption, but it’s still expensive in terms of fabricating
electrical machine, power electronics and battery pack[3]. Due to the high cost and
numbers of part, usages of CVT in machine are very limited.
1.4
Objective
To design and develop a new concept of compact CVT by the combination of current
CVT system and existing patterned CVT design which with purpose to reduce size of
the compact CVT for the usage of machinery.
1.5
Scope of Study
The approach in designing conceptual compact CVT will be as follow:
- Design a new conceptual of compact CVT with smaller size
- Create three-dimensional (3D) drawing for compact CVT
5
1.6
Project Significance
The design and development will be based on finding the suitable type of CVT or invent
a new CVT system to combine it with the previously patterned CVT. The challenge is
choosing the right type of new CVT model to be used, whereby variation of new CVT
model are still required a lot of studies. The study of CVT and it innovation are needed
to build a new conceptual CVT. Hence, the developed system is expected to be
compatible with minimum load and torque requirement for small power machinery or
vehicles.
6
CHAPTER 2
LITERATURE REVIEW
2.1
Fundamental of CVT
Continuous variable transmission (CVT) or CVT-hybrid is the new kind of technology
used in most modern compact and sub-compact vehicles, including minivan. This
technology is differs from manual or automatic transmission system in term of its ability
to adjust gear shift ratio coverage range continuously [4]. There are several types of
CVT system that can be found in market, among the popular CVT are belt-pulley CVT,
toroidal CVT, and cone based CVT. However, there are still many inventions of
conceptual CVT system which have not been commercialized.
7
Automotive company more interest in developing CVT compare to manual or
automatic because of its ability to maximize the power as well as enhance fuel efficiency.
By refer to Figure 2.1, CVTs also can give more comfort drive by eliminating “shift
shock” during gear change. CVT also has the capability to allow the engine to revolute
almost immediately and at the same time delivers maximum torque to move the vehicles.
Better control of engine's speed range may also indirectly help in reduce greenhouse
emissions. Vehicles installed with CVT have many advantages; however there are a few
disadvantages as well. Main problems in CVT car were user acceptance. For new CVT
car user, driver may not feel the accelerations since CVT always keeps the RPM at
lowest compare to manual and automatic. Transitorq, one of the machine manufacturers
in the history had tried to install CVT in their machine such as lathe and bore machine.
Due to the high manufacturing cost, productions of CVT base machine are limited and
replace with automatic transmission system [6].
Figure 2.1: Comparison of RPM performance between Manual Transmission (MT) with
Continuous Variable Transmission (CVT) [5]
8
2.1.1
Belt-pulley CVT
Although there are various types of CVT in the market, most of the cars are using a pair
of variable diameter pulley with belt running between them. This pair of variable
diameter shaped like two cones in different directions. Figure 2.2 shows two different
state of transmission with two different pulley groove width. Normally low gear state
are efficient during starting out of vehicles, meanwhile overdrive gear or higher gear
more to fuel efficiency.
Figure 2.2: Belt-pulley CVT operations [6]
Belt is usually in V-shape along the cross section, which this pattern can increase
the frictional grip between the belt and the surface of the cones. Compared to metal belt,
material properties of rubber belt allow it widely used in small power vehicles such as
scooter and snowmobile due to its limited torque [7]. As shown in Figure 2.3, metal Vbelt are built from various numbers of small steel blocks and ridded on thin flexible steel
bands. These thin flexible steel bands will in contact with the flanges of the pulleys [8].
9
Now days, Metal V-belt are crucial in designing pulley based CVT especially on
automobile that required high torque. Capabilities of metal v-belt to move the pulley at
high axial thrust and directly transmit the large torque from driving pulley to driven
pulley have become great benefits in CVT design [9].
Figure 2.3: Arrangement of Metal V-belt on CVT drive: (a) basic configuration ; (b)
Metal v- belt structure [10]
To allow the belt pulley CVT to function, each pulley should have two separate
parts with coned shaped. One side of the pulley must be moveable while another will be
fixed. The moving part will determine the diameter of the pulley. When it moves far
from fixed part, larger groove will be created to allow V-shaped belt move inward.
While the smaller the groove or width between two parts, the bigger diameter it is.
Since the belt is in constant length, changing of diameter for driving pulley will
subsequently produce a compression force among the v-belt. This force will transmit via
v-belt and create torque which will act on the driven pulley and change the diameter of
the driven pulley [11]. As driving pulley increase the radius, driven pulley will decrease
its radius to maintain the tension of belt. This mechanism had allowed both pulleys to
changes their radii relatively one to another, indirectly infinite number of gear ratio had
been created.
10
2.1.2
Toroidal CVT
Instead of belt and pulley, toroidal CVT used two discs and power roller to move the
vehicles. As shown in Figure 2.4, both discs are linked with 2 rollers or wheels which
located in opposite directions. Roller at toroidal CVT will have a similar function as vbelt in pulley based CVT whereby it transmits power from driving disc to driven disc.
Figure 2.4: Nissan Toroidal CVT [12]
Power roller can rotate in two axes, which spin in the horizontal axis to transfer
power from one to another. However, roller slit in and out around the vertical axis with
different angles created continuous variable gear ratio [13]. As the roller move to the
highest point or close to rim of driving disc, it must be contact with the driven disc near
the center of driven disc (Figure 2.5). This will result increase of speed and decrease of
torque. Toroidal CVT will in low gear condition when both rollers touch the driving disc
near the center and driven disc near the rim [14].
11
Figure 2.5: Mechanism of Toroidal CVT in overdrive mode (left) and low gear mode
(right) [15]
2.1.3
Cone based CVT
Cone based CVT or cone ring transmission (KRG) is made from two cones shaped roller
and linked by an idler or barrel shaped hub. As shown in Figure 2.6, both cone are in
opposite direction and act as driving cone and driven cone. Continuous variable gear
ratio is achieved by the movement of the idler that connected with a shaft. Based on the
required torque, or speed idler will move in the parallel direction to its shaft. By moving
Idler, diameter of the driving cone that contact with idler will change relatively to the
diameter of driven cone. Instead of using the idler, cone ring transmission (Figure 2.7)
had used barrel shaped hub to transmit the torque from one to another.
12
Figure 2.6: Concept of using cones ring CVT [16]
Figure 2.7: Open KRG transmission [17]
To overcome the weakness of cone based CVT, Warko had developed their own
concept of cone based CVT by using multiple cones in a system to transmit power. It’s
different with standard cone base CVT where by Warko's CVT used more than 1 set of
cones to transmit power
Figure 2.8 had shown the relation between numbers of cone and torque capacities
that can be produced by Warko's CVT. Warko's CVT consists of 3 major parts, which
are cones, barrel shaped hub in the middle and a ring. Cones will act as driving part, and
barrel as driven to the vehicles. Varies of gear ratio can be obtained by moving the ring
13
along the cone. When ring moved, cones will move as well in desired pattern and
maintain only touching the barrel hub at one point only. All this unique features of
Warko's CVT had offer high capabilities of torques and a wide range of transmission
[18].
Figure 2.8: Warko's CVT [19]
2.2
CVT patent
Studies of the existing patent are one of the important parts in this study. To accomplish
the objective, this study will be focus on the CVT that register under United State (US)
and European (EP) patent. Studies of patent are very important to identify and track the
current trend of CVT development. In the other hand, it may useful during the design
process by avoid infringing the patent right [20].
14
2.2.1
Patent 1 – Continuously Variable Transmission (EP Pat No. 0639732A1)
CVT with publication Number 0639732A1 was invented on 08.08.94 by using concept
belt and pulley. This invention is claimed to improve certain operating condition in
previously published patent (European Patent Application 91200513). Inventors for the
current patent claimed that the previous patent are not optimal and can limit the
efficiency and the life of the transmission.
Working principles for belt-pulley CVT had been introduced earlier in section
2.1 whereby it had two cones and connected with rubber or metal pushing v-belt.
Hydraulic or electrical powers are used in belt-pulley CVT to control the groove of the
pulley and create infinite gear ratio.
Based on the diagram at Figure 2.9, primary pulley with sheaves 3 and 4 are
fitted with shaft 2. Shaft 2 is linked to any input device such as engine or electric motor.
Which means speed of the engine will bring to shaft 2 and turn the primary pulley.
Torque from primary pulley will be transferred from drive belt 8 to sheaves 6, and 7 at
secondary pulley. Transmission ratio can be varies by the radial position of the drive belt
8. At secondary pulley, shaft 5 is the output of torque and couple to wheel. Sheaves 4
and 6 are support by cylinder 9, 10, 11, and 12 which actuated by primary and secondary
hydraulic pressure. In the other hand, sheave 4 and 6 will move respectively according to
the requirement of gear ratio.
Control system of this patent is done by electrical controller with hydraulic
pressure and assisted by fuzzy logic. Mechanical return mechanism also is applied at this
patent, by locating at the secondary pulley. Spring is used in here to return the position
of sheaves 6 to the original position during electrical power shut down or emergency
stop. By return the sheaves 6 to the initial state, wear and damage due to belt slip can be
avoided during restart of transmission.
15
Figure 2.9: CVT patent EP0639732A1 [21]
2.2.2
Patent 2 – Continuously variable transmission (US Pat No. 5324239)
Conventional belt-pulley CVT is using rubber belt or metal v-belt. Rubber belt had
limited torque capacity since it’s more function as pulling the secondary pulley. Metal
V-belt can produce more torque because it will act as pushing the belt; however, metal
V-belt are made of numbers of the small part and straight surface of each part had
decreased the area of contact. This patent US Pat No. 5324239 had invented to overcome
all those weakness. Instead of using rubber belt or metal V-belt, inventor had used series
of individual sized steel bands as shown in Figure 2.10.
16
Figure 2.10: Position of the steel bands [22]
Figure 2.11 shows the arrangement for 5 different lengths of steels bands that
sized in length and width so that uniform contact is made between the edge and the
surface of the sheaves. The steel bands will be design with different size so it may place
on one following with another. Compare to metal v-belt, steel bands can achieve
uniform contact with the pulley in respective diameter on which they run. With the
maximum surface of contact with sheaves, high torque transfer capacity is achieved.
Since steel bands are made of thin spring steel, only limited elastic of the steel will occur.
By this way, problems such as fatigues can be predicted and avoided to ensure long life
service. Used of steel bands may also reduce the wear due to high modulus of elasticity.
Figure 2.11: Steel bands arrangement
17
2.2.3
Patent 3 – Friction type continuously variable transmission (US Pat No.
5746676)
The inventor of this patent is Japanese from New Technology Network (NTN)
Corporation, Osaka, Japan, lead by Tatsuo Kawase. According to the patent registration,
this patent is done by May 5, 1998. Base on Figure 2.12, it is a CVT which has two
cones contacting the input shaft and output in a housing 1. This CVT used a different
mechanism compared to previous patents whereby double cones are used. This CVT had
an input shaft 2 and an output shaft 3 which support by a set of bearing in housing 1 in
both end to ensure both shaft are fixed in the same axis.
There are 2 unit of cone 4 which named as double cone due to it double cone
shaped. When the transmission accelerates, shaft 2 will rotate, and rotation is transmitted
to both double cones via input ring 7. Torque will be transfer from double cone to the
drive cone 8 and shaft 3 as well. Carrier 5 will move axially to change the contact
diameter between double cone 4 and drive cone 8. If the carrier 5 moved out of the
permissible range, double cone would disengage with the input ring 7 or drive cone 8
and cause failure.
Figure 2.12: Double cone friction CVT [23]
18
2.2.4
Patent 4 – Continuously variable transmission (US Pat No. 5888160)
Assigned by Nippon Seikō Kabushiki (NSK) Ltd, a group of Japanese Inventor had
registered a toroidal CVT patent on 30 March 1999. This invention is a combination of
toroidal CVT with toothed gear box and interchanging usage by clutches. The toroidal
CVT only functions during high turning but not during low speed turning either
backward movement.
Figure 2.13: Schematics view of continuously variable transmission [24]
Diagram shows in Figure 2.13 are the schematics view of CVT where the upper
right part is the toroidal CVT while the lower right part is toothed gear. Part with labeled
36(low speed) and 37(high speed) are the clutches which control the activation of
toroidal CVT or toothed gear. Same as other CVT, this design also have an input shaft
(46) and output shaft (16).
The input disc is labeled with 2 and output disc labeled with 4 are connected by a
power roller 8 which transmit the power from input disc 2 to output disc 4. When a
19
rotational motion reached the CVT, it would rotate the input disc as it is connected to the
driving shaft 17. The disc 2 will rotate the power roller as they are attached tightly on
both discs. After that, the torque will be transmitted to the output disc which are
concentric with the input disc. The rotational motion transmission is basically done by
friction force between discs and power rollers. Edges of power rollers which attached to
the disc are in a tangential manner; therefore, speeds are transmitted at any instant of
contacts.
Continuous variable gear ratio can be achieved when the power rollers change
their positions on discs 2 and 4. Power roller is fixed at the center of both disc, and it
may move and change the angle of inclination based on the requirement RPM. The
angles of the power roller will decide the contacting point which means if power rollers
contacted near the larger diameter on input disc, automatically it will in contact with
smaller diameter on the output disc, and vice verse. Gear ratio can be changed by
varying the effective diameter of input and output, and the gear ratio is continuously
variable in toroidal CVT.
2.3
Available CVT Product
Several researches had been carried out toward developing transmission for vehicles that
able to reduce energy consumption [25]. Until now days, there are more than hundred
models of vehicles using CVT.
2.3.1
Nissan Xtronic
Nissan is among the vehicle manufacturer that offers CVT to vehicles. However, Nissan
with their new developed CVT, Nissan Xtronic are the first CVT install in vehicles with
3.5 liters capacity engine, and it was the third generation of Nissan belt CVT after Hyper
20
CVT. Figures 2.14 had shown the CVT for 3.5 liters engine and Figure 2.14 shows the
construction of CVT belt.
Table 2.1: Nissan Xtronic [26]
Product Name
Xtronic CVT
Developer
Nissan
Type of CVT
Belt pulley(metal pushing V-belt)
Application
Tiida
Lafesta
Nissan Teana
Engine displacement(Liter)
1.5
2.5
3.5
Maximum power transfer(kW)
80
134
185
Maximum torque transfer(Nm)
148
228
326
Gear ratio
2.561 ~ 0.427
2.349 ~ 0.394
2.371 ~ 0.439
21
2.3.2
Nissan Extroid
Nissan Extroid developed by Nissan to provide powerful driving performance.
Compared with Nissan Xtronic, this model provide higher torque output and used in
rear-wheel drive car. Figure 2.16 shows that Nissan Extroid CVT use 2 set of
input/output discs and increase the output torque respectively via propeller shaft.
Table 2.2: Nissan Extroid [27] [28]
Product Name
Extroid
Developer
Nissan
Type of CVT
Application
Engine Displacement(L)
Toroidal
Nissan Cedric Y34
3.5
Maximum power transfer(kW)
205.94
Maximum torque transfer(Nm)
387.5
Gear ratio
2.857 ~ 0.660
22
2.3.3
Audi Multitronic
In early 1999, Audi had developed a variable automatic gearbox also named as CVT
gearbox and named it as Multitronic. Audi’s technical specialist had made some
modification on this CVT by adopting link plate chain (Figure 2.16). Instead of using
metal v-belt, link plate chain had successfully transfer torque more efficiently from input
to the output disc and produce higher torque and force for the vehicle.
Table 2.3: Audi Multitronic [29]
Product name
Developer
Type of CVT
Application
Multitronic
Audi
Belt-pulley(chain belt)
Audi A6 Avant
Engine Displacement (L)
3.0
Maximum power transfer (kW)
150
Maximum torque transfer (Nm)
400
Gear ratio
2.404 ~ 0.382
23
2.3.4
Warko CVT
During 6th International CTI Symposium of Innovative Automotive Transmissions,
Warko had presented their new invention in cone CVT which named it as Warko CVT.
Table 2.5 shows some information that released by Warko which using 4 cones, 6 cones
and 8 cones to produce the different value of torque.
Table 2.4: Warko CVT [30]
Product Name
Warko CVT
Developer
Warko
Type of CVT
Cone based
Application
Number of Cone
Maximum torque transfer (Nm)
Maximum power transfer (kW)
Gear ratio
Wind generator, agriculture machinery
4
6
8
200
300
400
45 - 149
1~8
24
2.3.5
Comparison
Comparison had been done based on several CVT products to determine all possible strengths and weakness of various kind of CVT
product as shown in Table 2.6.
Table 2.5: Comparison of CVT products
Product
Audi Multitronic
Nissan Extroid
Warko CVT
Belt pulley (Chain belt)
Toroidal
Cone based
Nissan Tiida/Lafesta/Teana
Audi A6 Avant
Nissan Cedric Y34
Engine
displacement(L)
Max power(kW)
1.5 - 3.5
3.0
3.5
Wind generator,
agriculture
machinery
-
80 - 185
150
205.94
45 – 149
Max torque(Nm)
148 - 326
400
387.5
200 – 400
0.427- 2.371
2.404 – 0.382
2.857 – 0.660
1–8
Type of CVT
Application
Gear ratio
Nissan Xtronic
Belt pulley
(Metal pushing v-belt)
57
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