Dual clutch transmission seminar report
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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
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