BACHELOR OF TECHNOLOGY

SEMINAR REPORT

Proposed topic:

Dual Clutch Transmission System

Submitted by:

Deepak kumar

Department of Mechanical Engineering

Seth Jai Prakash Mukandlal Institute of Engineering and Technology

Affiliated to Kuruksehtra University

CONTENTS

1. Transmission system

2. Torque converter

3. Manual Transmission system

4. Automatic Transmission system

5. Stages of automatic transmission system

6. Clutch

7. Dual Clutch transmission system

8. History of transmission system

9. Overview Of DCT

10. Clutch used in DCT

11. Dual vs automatic vs manual transmission system

Transmission system

The mechanism that transmits the power developed by the engine of automobile to the engine to

the driving wheels is called the TRANSMISSION SYSTEM (or POWER TRAIN).It is

composed of –

Clutch

The gear box

Propeller shaft

Universal joints

Rear axle

Wheel

Tyres

Requirements of transmission system Provide means of connection and disconnection of engine with rest of power train without

shock and smoothly.

Provide a varied leverage between the engine and the drive wheels

Provide means to transfer power in opposite direction.

Enable power transmission at varied angles and varied lengths.

Enable speed reduction between engine and the drive wheels in the ratio of 5:1.

Enable diversion of power flow at right angles.

Provide means to drive the driving wheels at different speeds when required.

Bear the effect of torque reaction, driving thrust and braking effort effectively.

Torque Converter Torque converter is a hydraulic transmission which increases the torque of the vehicle reducing

its speed. It provides a continuous variation of ratio from low to high. The key characteristic of a

torque converter is its ability to multiply torque when there is a substantial difference between

input and output rotational speed, thus providing the equivalent of a reduction gear. cars with an

automatic transmission have no clutch that disconnects the transmission from

the engine. So, they use an amazing device called a torque converter.

Manual transmission system In this type of transmission system, the driver has to manually select and engage the gear

ratios

Clutch fully depressed

The clutch is fully disengaged when the pedal is fully depressed. There will be no torque being

transferred from the engine to the transmission and wheels. Fully depressing the clutch allows

the driver to change gears or stop the vehicle.

Clutch slips

The clutch slips are the point that vary between being fully depressed and released. The clutch

slip is used to start the vehicle from a stand still. It then allows the engine rotation to adjust to the

newly selected gear ratio gradually It is recommended not to slip the clutch for a long time

because a lot of heat is generated resulting in energy wastage.

Clutch fully released

The clutch is fully engaged when the pedal is fully released. All the engine torque will be

transmitted to the transmission. This results in the power being transmitted to the wheels with

minimum loss.

Automatic transmission Automatic transmission system is the most advanced system in which drives mechanical

efforts are reduced very much and different speeds are obtained automatically. This system is

generally also called hydromantic transmission. It contains epicycle gear arrangement, fluid

coupling and torque converter. In this planetary gears sets are placed in series to provide

transmission.

This type of transmission is used by Skoda, Toyota, Lexus, etc.

Epicyclical gearing (planetary gearing): - it is a gear system consisting of one or more outer

gears, or planet gears, revolving about a central gear. By using epicycles gear, different torque

speed ratio can be obtained. It also compacts the size of gear box.

Stages of automatic transmission: - Park(P): - selecting the park mode will lock the transmission, thus restricting the vehicle from

moving.

Reverse(R): - selecting the reverse mode puts the car into reverse gear, allowing the vehicle to

move backward.

Neutral (N): - selecting neutral mode disconnects the transmission from the wheel.

Low (L): - selecting the low mode will allow you to lower the speed to move on hilly and

middy areas.

Drive (D): - selecting drive mode allows the vehicle to move and accelerate through a range of

gears.

Clutch A clutch is a mechanism which enables the rotary motion of one shaft to be transmitted at will

to second shaft, whose axis is coincident with that of first.

Clutch is located between engine and gear box. When the clutch is engaged, the power flows

from the engine to the rear wheels through the transmission system and the vehicle moves. when

the clutch is disengaged, the power is not transmitted to the rear wheels and the vehicle stops,

while the engine is still running.

Clutch is disengaged when Starting the engine,

b) Shifting the gears,

c) Idling the engine

clutch is engaged only when the vehicle is to move and is kept engaged when the vehicle is

moving.

Function of a Clutch: -

a) To permit engagement or disengagement of a gear when the vehicle is stationary and the

engine is running

b) To transmit the engine power to the road wheels smoothly without shock to the transmission

system while setting the wheel in motion.

c) To permit the engaging of gears when the vehicle is in motion without damaging the gear

wheels.

Principle of operation of a clutch: - The clutch principle is based on friction. when two friction surface are brought in contact with

each other and pressed they are united due to friction between them. If one is revolved the other

will also revolve. The friction between the two surfaces depends upon.

i. Area of the surface,

ii. Pressure applied upon them,

iii. Coefficient of friction of the surface materials

Here, one surface is considered as driving member and the other as driven member.

The driving member of a clutch is the flywheel mounted on the crankshaft, the driven member is

the pressure plate mounted on the transmission shaft. Friction surfaces (clutch plates) are

between the two members (driving and driven). On the engagement of the clutch, the engine is

connected to the transmission (gear box) and the power flows from the engine to the rear wheels

through the transmission system. when the clutch is disengaged by pressing a clutch pedal, the

engine is disconnected from the transmission and consequently the power does not flow to the

rear wheels while the engine is still running.

Dual clutch transmission

A dual-clutch transmission, (DCT) (sometimes referred to as a twin-clutch

transmission or double-clutch transmission), is a type of automatic

transmission or automated automotive transmission. It uses two separate clutches for odd and

even gear sets. It can fundamentally be described as two separate manual transmissions (with

their respective clutches) contained within one housing, and working as one unit. They are

usually operated in a fully automatic mode, and many also have the ability to allow the driver

to manually shift gears in semi-automatic model, albeit still carried out by the transmission's

electro-hydraulics.

History

This type of transmission was invented by Frenchman Adolphe Kégresse just before World War

II but he never developed a working model. The first development of the Twin Clutch or Dual-

clutch transmission started in the early part of 1980 under the guidance of Harry

Webster at Automotive Products (AP), Leamington Spa with prototypes built into the Ford Fiesta

Mk1, Ford Ranger & Peugeot 205. Initially, the control systems were based on purely

analogue/discrete digital circuitry with patents filed in July 1981. All of these early AP Twin

Clutch installations featured a single dry clutch and multi-plate wet clutch. Following

discussions with VW/Porsche, DCT work continued from Porsche in-house development, for

Audi and Porsche racing cars later in the 1980s, when computers to control the transmission

became compact enough: The Porsche (English: dual-clutch gearbox) (PDK) used in the Porsche

956 and 962 Le Mans race cars from 1983, and the Audi Sport Quattro S1 rally car.

A dual-clutch transmission eliminates the torque converter as used in conventional epi cyclic-

geared automatic transmissions. Instead, dual-clutch transmissions that are currently on the

market primarily use two oil-bathed wet multi-plate clutches, similar to the clutches used in most

motorcycles, though dry clutch versions are also available.

The first series production road car with a DCT was the 2003 Volkswagen Golf Mk4 R32.

As of 2009, the largest number of sales of DCTs in Western Europe are by various marques of

the German Volkswagen Group, though this is anticipated to lessen as other transmission makers

and vehicle manufacturers make DCTs available in series production automobiles. In 2010, on

BMW Canada's website for the 3 Series Coupe, it is described both as a 7-speed double-clutch

transmission and as a 7-speed automatic transmission. It is actually a dual-clutch semi-automatic.

Overview

In DCTs where the two clutches are arranged concentrically, the larger outer clutch drives the

odd numbered gears, while the smaller inner clutch drives the even numbered gears. Shifts can

be accomplished without interrupting torque distribution to the driven road wheels, by applying

the engine's torque to one clutch at the same time as it is being disconnected from the other

clutch. Since alternate gear ratios can pre-select an odd gear on one gear shaft while the vehicle

is being driven in an even gear. (and vice versa), DCTs are able to shift more quickly than cars

equipped with single-clutch automated-manual transmissions (AMTs), a.k.a. single-clutch semi-

automatics. Also, with a DCT, shifts can be made more smoothly than with a single-clutch AMT,

making a DCT more suitable for conventional road cars.

Clutch type

Dual-clutch transmissions use two fundamentally different types of clutches: either two wet

multi-plate clutches, bathed in oil (for cooling)—or two dry single-plate clutches. The wet clutch

design is generally used for higher torque engines that can generate 350 newton

metres (258 lbf·ft) and more (the wet multi-plate clutch DCT in the Bugatti Veyron is designed

to cope with 1,250 N ·m (922 lbf·ft), whereas the dry clutch design is generally suitable for

smaller vehicles with lower torque outputs up to 250 N ·m (184 lbf ·ft).However, while the dry

clutch variants may be limited in torque compared to their wet clutch counterparts, the dry clutch

variants offer an increase in fuel efficiency, due to the lack of pumping losses of the transmission

fluid in the clutch housing.

DIFFERENCE BETWEEN DUAL CLUTCH AND AUTOMATIC

TRANSMISSION

An automatic transmission (without any extra modifiers) refers to a torque-converterautomatic

transmission. There is no direct mechanical connection between the engine and the wheels -

instead torque is transferred through transmission fluid which enters on the turbine side and

drives the output pump side (which connects to the wheels). There are 2 pedals, and usually a

PRND2L shifter, which may optionally have a "tiptronic" mode to allow gear-changing via up-

down motions. Automatic transmissions also feature a planetary gear arrangement (see below)

except for Honda. Most automatic transmissions have a noticeable lag when you tell the to

manually shift (.75-1 second is common) and don't downshift very smoothly (no rev matching

from computer). Automatic transmissions will also creep when you release your foot off the

brake in Drive. Automatic transmissions by their design can also overheat and fail when pushed

to the limits frequently because all energy must be transferred through this torque converter, and

torque converters reduce the maximum possible efficiency of automatics. 

A dual-clutch transmission (DCT, Volkswagen DSG, Porsche PDK) is essentially a computer-

operated manual transmission with two clutches (one for odd gears, one for even gears). This

allows near-instant shifting (when coupled with computer control) in as little as 10ms - going

from 3rd gear to 4th gear, the odd clutch will prepare to disengage 3rd gear while the even clutch

prepares to engage 4th gear, and this can be done super quickly. DCTs feature a typical manual

transmission gear layout. Usually, to shift in a manual transmission (even an automated manual

one, SMG by BMW is an example), you have to disengage the clutch, shift, engage clutch -

computers can reach 0.1s shifts, skilled drivers average 0.3-0.5s. The two clutches in a DCT

make this faster. Dual-clutch transmissions typically handle high-performance shifting well

responding quickly, and will nearly always have paddles or a +/- tiptronic mode. They still only

have 2 pedals, and if you wanted to you could leave the car in Drive the entire time and let it

shift itself

References

1. www.quora.com

2. www.sae.com

3. www.wikipedia.com

4. www.Allaboutcars.com

5. www.youtube.com

6. worldwide.espace.com

7. web.archive.com