105813501 dct dual clutch transmission

8/12/2019 105813501 DCT Dual Clutch Transmission

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INTRODUCTION

1.1 TRANSMISSION

Transmission is the mechanism through which the driving torque of the engine is

transmitted to the driving wheel of the vehicle so that the motor vehicle can move on the

road. The reciprocating motion of the piston turns a crankshaft rotating a flywheel through

the connecting rod .The circular motion of the crankshaft is to be now transmitted to the

rear wheels .It is transmitted through the clutch, gear box, universal joints, propeller shaft

or the drive shaft, differential and axles extending to the wheels. The application of the

engine power to the driving wheels through all these parts is called P !"#

T#$%&'I&&I % .The power system is usually the same on all modern passenger cars and

trucks, but its arrangement may vary according to the method of drive and type of

transmission units.

1.2 PURPOSE OF TRANSMISSION:

It enables the engine to be disconnected from the driving wheels.

It enables the running engine to be connected to driving wheel smoothly andwithout shock.

It enables the leverage between the engine and the driving wheels to be varied.

It enables the reduction of engine speed in the ratio of ()* in case of passenger

cars and in greater ratio in case of +orries.

It enables the driving wheels to be driven at different speeds.

It enables turning the driving through - degrees.

It enables the relative movement between the engine and the driving wheel.

1.3 CLUTCH

In all vehicles using a transmission virtually all modern vehicles/, a coupling device is

used to separate the engine and transmission when necessary. The clutch accomplishes this

in manual transmissions. !ithout it, the engine and tires would at all times be inextricably

linked, and anytime the vehicle stopped the engine would perforce stall.

BCET, ME Dept Dual clutch transmissionPage *
http://wiki/Clutchhttp://wiki/Clutchhttp://wiki/Clutch


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!ithout the clutch, changing gears would be very difficult, even with the vehicle moving

already) deselecting a gear while the transmission is under load requires considerable force,

and selecting a gear requires the revolution speed of the engine to be held at a very precise

value which depends on the vehicle speed and desired gear. In a car the clutch is usually

operated by a pedal0 on a motorcycle, a lever on the left handlebar serves the purpose.

1. !hen the clutch pedal is fully depressed, the clutch is fully disengaged, and no torque is

transferred from the engine to the transmission and by extension to the drive wheels/. In

this uncoupled state it is possible to select gears or to stop the car without stopping the

engine.

2. !hen the clutch pedal is fully released, the clutch is fully engaged, and practically all of

the engine1s torque is transferred. In this coupled state, the clutch does not slip, but rather

acts as rigid coupling, and power is transmitted to the wheels with minimal practical waste

heat.

3. 2etween these extremes of engagement and disengagement the clutch slips to varying

degrees. !hen the clutch slips it still transmits torque despite the difference in speeds

between the engine crankshaft and the transmission input because this torque is transmitted

by means of friction rather than direct mechanical contact.

4. 3onsiderable power is wasted as heat which is dissipated by the clutch/. Properly

applied, slip allows the vehicle to be started from a standstill, and when it is already

moving, allows the engine rotation to gradually adjust to a newly selected gear ratio.

5. +earning to use the clutch efficiently requires the development of muscle memory and a

level of coordination analogous to that required to learn a musical instrument or to play a

sport.

BCET, ME Dept Dual clutch transmissionPage 4
http://wiki/Torquehttp://wiki/Muscle_memoryhttp://wiki/Muscle_memoryhttp://wiki/Torquehttp://wiki/Muscle_memory


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DUAL CLUTCH TRANSMISSION

2.1 INTRODUCTION

$ semi-au !ma i" #a$smissi!$ also known as "%u "&%ess ma$ua% #a$smissi!$ ,

'ua%-"%u "& #a$smissi!$ , au !ma e' ma$ua% #a$smissi!$ , e-(ea# , s&i) - #!$i" , )%a**+

*a''%e (ea#,! , or 'i#e" s&i) (ea#,! / is a system which uses electronic sensors,

processors and actuators to do gear shifts on the command of the driver. This removes the

need for a clutch pedal which the driver otherwise needs to depress before making a gearchange, since the clutch itself is actuated by electronic equipment which can synchronise

the timing and torque required to make gear shifts quick and smooth. The system was

designed by "uropean automobile manufacturers to provide a better driving experience,

especially in cities where congestion frequently causes stop5and5go traffic patterns.

"laborated form of manual transmission in which two internal shafts, each connected

to the input via an electronically controlled clutch, are coordinated such as to achieve a

uniterrupted flow of torque to the driven wheels during gear changes. $s well as reducing

acceleration times, a dual clutch transmission also enchances refinement over a

convectional manual or manual gearbox.

'ost people know that cars come with two basic transmission types) manuals, which

require that the driver change gears by depressing a clutch pedal and using a stick shift, and

automatics , which do all of the shifting work for drivers using clutches , a torque converter

and sets of planetary gears. 2ut there1s also something in between that offers the best of both worlds 55 the 'ua%-"%u "& #a$smissi!$ , also called the semi5automatic transmission,

the 6clutchless6 manual transmission and the automated manual transmission.

In the world of race cars, semi5automatic transmissions, such as the se ue$ ia% ma$ua%

(ea#,! or &'7/, have been a staple for years. 2ut in the world of production vehicles,

it1s a relatively new technology 55 one that is being defined by a very specific design known

as the dual5clutch, or direct5shift, gearbox.

BCET, ME Dept Dual clutch transmissionPage 8
http://wiki/Gear_shifthttp://wiki/Drivinghttp://wiki/Clutchhttp://wiki/Europehttp://wiki/Automobile_manufacturerhttp://wiki/Cityhttp://wiki/Traffichttp://auto.howstuffworks.com/transmission.htmhttp://auto.howstuffworks.com/automatic-transmission.htmhttp://auto.howstuffworks.com/clutch.htmhttp://auto.howstuffworks.com/torque-converter.htmhttp://auto.howstuffworks.com/sequential-gearbox.htmhttp://auto.howstuffworks.com/sequential-gearbox.htmhttp://wiki/Gear_shifthttp://wiki/Drivinghttp://wiki/Clutchhttp://wiki/Europehttp://wiki/Automobile_manufacturerhttp://wiki/Cityhttp://wiki/Traffichttp://auto.howstuffworks.com/transmission.htmhttp://auto.howstuffworks.com/automatic-transmission.htmhttp://auto.howstuffworks.com/clutch.htmhttp://auto.howstuffworks.com/torque-converter.htmhttp://auto.howstuffworks.com/sequential-gearbox.htmhttp://auto.howstuffworks.com/sequential-gearbox.htm


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2.2 OPERATION OF DCT

In standard mass5production automobiles, the gear lever appears similar to manualshifts, except that the gear stick only moves forward and backward to shift into higher and

lower gears, instead of the traditional 95pattern. The 2ugatti :eyron uses this approach for

its ;5speed transmission. In


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faster shifting techniques like powershifting require a heavier gearbox

or clutch or even a twin5clutch gearbox .

2.3 /ASIC DESI0N OF DUAL CLUTCH TRNSMISSION

$ dual5clutch transmission offers the function of two manual gearboxes in one. To

understand what this means, it1s helpful to review how a conventional manual gearbox

works. !hen a driver wants to change from one gear to another in a standard stick5shift car,

he first presses down the clutch pedal. This operates a single clutch, which disconnects the

engine from the gearbox and interrupts power flow to the transmission. Then the driver uses

the stick shift to select a new gear, a process that involves moving a toothed collar from one

gear wheel to another gear wheel of a different si=e. >evices called s+$"!$i e#s match

the gears before they are engaged to prevent grinding. nce the new gear is engaged, the

driver releases the clutch pedal, which re5connects the engine to the gearbox and transmits

power to the wheels. &o, in a conventional manual transmission, there is not a continuous

flow of power from the engine to the wheels. Instead, power delivery changes from !$ to

!)) to !$ during gearshift, causing a phenomenon known as 6shift shock6 or 6torque

interrupt.6 3T/

BCET, ME Dept Dual clutch transmissionPage @
http://wiki/Powershiftinghttp://wiki/Powershiftinghttp://wiki/Twin-clutch_gearboxhttp://wiki/Powershiftinghttp://wiki/Twin-clutch_gearbox


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$ dual5clutch gearbox, by contrast, uses two clutches, but has no clutch pedal.

&ophisticated electronics and hydraulics control the clutches, just as they do in a&tandard automatic transmission. In a >3T, however, the clutches operate independently.

ne clutch controls the odd gears first, third, fifth and reverse/, while the other controls the

even gears second, fourth and sixth/. Asing this arrangement, gears can be changed

without interrupting the power flow from the engine to the transmission.

&equentially, it works like this)

A "a# #a e%%i$( i$ se"!$' (ea# is "!$ #!%%e' ,+ &e i$$e# "%u "& .P! e# is se$

! se"!$' (ea# a%!$( &e !u e# #a$smissi!$ s&a)

As &e "a# i$"#eases s*ee' &e "!m*u e# 'e e" s &e $e (ea#s&i) *!i$ a$'

&e &i#' (ea# is *#e-se%e" e'.

&e$ &e '#i e# "&a$(es (ea#s &e i$$e# "%u "& 'ise$(a(es a$' &e !u e#

"%u "& is a" i a e'.

T&e *! e# is #a$s)e##e' a%!$( &e i$$e# #a$smissi!$ s&a) s ! &e *#e-

se%e" e' (ea#.

>rivers can also choose a fully automatic mode that relinquishes all gear5changing

duties to the computer. In this mode, the driving experience is very similar to that delivered

by a conventional automatic. 2ecause a >3T transmission can 6phase out6 one gear and

6phase in6 a second gear, shift shock is reduced. 'ore importantly, the gear change takes

place under load so that a permanent flow of power is maintained. $n ingenious two5shaft

construction separating the odd and even gears makes all of this possible.

BCET, ME Dept Dual clutch transmissionPage ?


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2.4 DUAL CLUTCH TRANSMISSION SHAFTS

$ two5part transmission shaft is at the heart of a >3T. Anlike a conventional manual

gearbox, this houses all of its gears on a single input shaft, the >3T splits up odd and even

gears on two input shafts. The outer shaft is hollowed out, making room for an inner shaft,

which is nested inside. The outer hollow shaft feeds second and fourth gears, while the

inner shaft feeds first, third and fifth.

The diagram below shows this arrangement for a typical five5speed >3T. %otice that

one clutch controls second and fourth gears, while another0 independent clutch controls

first, third and fifth gears. That1s the trick that allows lightning5fast gear changes and keeps power delivery constant. $ standard manual transmission can1t do this because it must use

one clutch for all odd and even gears.

3T/

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2.5 MULTI PLATE CLUTCH

&ince a dual5clutch transmission is similar to an automatic, one might think that it

requires a torque converter, which is how an automatic transfers engine torque from the

engine to the transmission. >3Ts, however, don1t require torque converters. Instead, >3Ts

currently on the market use wet multi5plate clutches. $ 6wet6 clutch is one that bathes the

clutch components in lubricating fluid to reduce friction and limit the production of heat.

&everal manufacturers are developing >3Ts that use dry clutches, like those usually

associated with manual transmissions, but all production vehicles equipped with >3Ts

today use the wet version. 'any motorcycles have single multi5plate clutches.


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ual !et 3lutch >esign/

To disengage the clutch, fluid pressure inside the piston is reduced. This allows the

piston springs to relax, which eases pressure on the clutch pack and pressure plate.

2.6 CONTROLLIN0 OF DCT

$ method of controlling the clutches of a dual clutch transmission during a two5gear

positive downshift, wherein the first clutch drives an initial gear and the final gear and the

second clutch drives an intermediate gear. The torque transfer across each clutch is

controlled so that the torque output of the transmission will be linearly changed over from

the first clutch to the second clutch to cause the engine to track a target engine speed

profile. The method changes over the gears driven by the first clutch from the initial gear to

the final gear as the engine continues to tracks the target speed. The torque transfer across

each clutch is controlled so that the torque output will be linearly changed back from the

second clutch to the first clutch in an inversely proportional rate to continue to cause the

engine to track the target engine speed profile.

BCET, ME Dept Dual clutch transmissionPage


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AD7ANTA0ES AND DISAD7ANTA0ES

3.1 AD7ANTA0ES

In principle, the >3T behaves just like a standard manual transmission)

It1s got input and auxiliary shafts to house gears, synchroni=ers and a clutch. It

doesn1t have a clutch pedal, because "!m*u e#s s!%e$!i's a$' &+'#au%i"s do the

actual shifting. "ven without a clutch pedal, the driver can still 6tell6 the computer

when to take action through paddles, buttons or a gearshift.

>river experience is just one of the many advantages of a >3T. !ith upshifts

taking a mere B milliseconds, many feel that the >3T offers the most dynamic

acceleration of any vehicle on the market.

It certainly offers smooth acceleration by eliminating the shift shock that

accompanies gearshifts in manual transmissions and even some automatics. 2est of

all, it affords drivers the luxury of choosing whether they prefer to control the

shifting or let the computer do all of the work.

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Fi( 3.1. Au'i TT R!a's e#

O$e !) se e#a% Au'i m!'e%s a ai%a,%e i & a 'ua%-s&i) #a$smissi!$

Perhaps the most compelling advantage of a >3T is improved )ue% e"!$!m+ .

2ecause power flow from the engine to the transmission is not interrupted, fuel

efficiency increases dramatically. &ome experts say that a six5speed >3T can

deliver up to a *- percent increase in relative fuel efficiency when compared to a

conventional five5speed automatic.

3.2 DISAD7ANTA0ES

'any car manufacturers are interested in >3T technology. 9owever, some

automakers are wary of the additional costs associated with modifying production

lines to accommodate a new type of transmission. This could initially drive up the

costs of cars outfitted with >3Ts, which might discourage cost5conscious

consumers.

In addition, manufacturers are already investing heavily in alternate transmission

technologies. ne of the most notable is the continuously variable transmission , or3:T. $ 3:T is a type of automatic transmission that uses a moving pulley system

and a belt or chain to infinitely adjust the gear ratio across a wide range. 3:Ts also

reduce shift shock and increase fuel efficiency significantly. 2ut 3:Ts can1t handle

the high torque demands of performance cars.>3Ts don1t have such issues and are

ideal for high5performance vehicles. In "urope, where manual transmissions are

preferred because of their performance and fuel efficiency, some predict that >3Ts

will capture 4@ percent of the market. Cust one percent of cars produced in !estern

"urope will be fitted with a 3:T by 4-*4.

BCET, ME Dept Dual clutch transmissionPage **
http://auto.howstuffworks.com/cvt.htmhttp://auto.howstuffworks.com/cvt.htm


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Dua%-"%u "& T#a$smissi!$s: 8Pas P#ese$ .9

4.1 PAST

The man who invented the dual5clutch gearbox was a pioneer in automotive

engineering. $dolphe DEgresse is best known for developing the half5track, a type of

vehicle equipped with endless rubber treads allowing it to drive off5road over various forms

of terrain. In * 8 , DEgresse conceived the idea for a dual5clutch gearbox, which he hoped

to use on the legendary 3itroFn 6Traction6 vehicle. Anfortunately, adverse business

circumstances prevented further development.

2oth $udi and Porsche picked up on the dual5clutch concept, although its use was

limited at first to racecars. The @? and ?43 racecars included the P!#s"&e Dua% %u "& ,

or P>D. In * B?, a Porsche ?4 won the 'on=a *--- Dilometer !orld &ports Prototype3hampionship race 55 the first win for a car equipped with the P>D semi5automatic paddle5

shifted transmission. $udi also made history in * B@ when a &port quattro &* rally car

equipped with dual5clutch transmission won the Pikes Peak hill climb, a race up the (,8--5

meter5high mountain.


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4.2 PRESENT

3ommerciali=ation of the dual5clutch transmission, however, has not been feasible until

recently. :olkswagen has been a pioneer in dual5clutch transmissions, licensing

2org!arner1s >ualTronic technology. "uropean automobiles equipped with >3T include

the :olkswagen 2eetle, 7olf, Touran, and Cetta as well as the $udi TT and $80 the &kodactavia0 and the &eat $ltea, Toledo and +eon.


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APPLICATIONS

5.1 TRUC S AND /USES &emi5automatic transmissions have also made its way into the truck and bus market in

the early 4---s. :olvo offers its I5shift on its heavier trucks and buses, while H< markets its

$&Tronic system for buses and coaches. These gearboxes have a place in public transport

as they have been shown to significantly reduce fuel consumption.

In the AD though, semi5automatic transmission has been very popular on buses for

some time, from the * @-s right through to the * B-s, an example being the well known+ondon #oute master , although the latter could also be driven as a fully automatic in the 8

highest gears. +eyland manufactured many buses with semi5automatic transmission,

including its +eopard and Tiger coaches.


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clutch lever would go on traditional motorcycles.

C>NCLUSIONS

%ew environmental and fuel efficiency legislation coupled with advances in electronics and

manufacturing techniques have triggered new automated transmission technologies. The

most likely winner that will replace traditional automatics and boost market penetration of

automated transmissions will be the dual clutch transmission >3T/.

BCET, ME Dept Dual clutch transmissionPage *@
http://factsheet.aspx/?id=153http://factsheet.aspx/?id=149http://factsheet.aspx/?id=149http://factsheet.aspx/?id=153http://factsheet.aspx/?id=149


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REFERENCES

*. $utomobile engineering by #.2. 7upta

4. google.com

8. howstuffwork.com

(. wikipedia.com

@. autoworld.com

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105813501 dct dual clutch transmission

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