PRELIMINARY DESIGN OF NEW CONCEPT COMPACT ...

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 6

2.1.1 Belt-pulley CVT 8

viii

2.1.2 Toroidal CVT 10

2.1.3 Cone based CVT 11

2.2 CVT patent 13

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

(US PAT NO. 5888160) 18

2.3 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 Concept design 33

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 Concept Development 39

4.4.1 Cone 40

4.4.2 Idler 40

4.4.3 Controlling device 41

4.4.4 Casing 42

4.5 Generation of Concept 42

4.5.1 Design Concept 1 42




4.6 Modeling and Design Development 45

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 Gear Ratio 51

CHAPTER 5 CONCLUSION 55

5.1 Introduction 55

5.2 Recommendation 56

5.3 Conclusion 56

REFERENCES 57

APPENDIX

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




4.10 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 V-

belt 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 v-

belt 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 Toroidal

Application Nissan Cedric Y34

Engine Displacement(L) 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 Multitronic

Developer Audi

Type of CVT Belt-pulley(chain belt)

Application 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 Wind generator, agriculture machinery

Number of Cone 4 6 8

Maximum torque transfer (Nm) 200 300 400

Maximum power transfer (kW) 45 - 149

Gear ratio 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

Nissan Xtronic

Audi Multitronic Nissan Extroid

Warko CVT

Type of CVT Belt pulley (Metal pushing v-belt)

Belt pulley (Chain belt) Toroidal Cone based

Application Nissan Tiida/Lafesta/Teana Audi A6 Avant Nissan Cedric Y34 Wind generator,

agriculture machinery

Engine displacement(L)

1.5 - 3.5 3.0 3.5 -

Max power(kW) 80 - 185 150 205.94 45 – 149

Max torque(Nm) 148 - 326 400 387.5 200 – 400

Gear ratio 0.427- 2.371 2.404 – 0.382 2.857 – 0.660 1 – 8

57

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