What is a DSG box - advantages and disadvantages of a dual clutch gearbox
Content
Modern life cannot be imagined without cars, and urban traffic should be as comfortable as possible for the driver. The convenience of driving a car is provided with the help of various transmissions (automatic transmission, robotic gearbox).
The robotic box is very popular due to the smoothness of movement and economical fuel consumption, the presence of a manual mode that allows you to adjust the driving style to the needs of the driver.
The principle of operation of the DSG gearbox
DSG is a manual transmission equipped with an automatic gear change drive and has two clutch baskets.
The DSG box is connected to the engine through two clutches located axially. The odd and rear stages operate through one clutch, and the even ones through the other. Such a device provides a smooth change of steps without reducing and interrupting power, carrying out a continuous transmission of torque from the motor to the drive axle of the wheels.
During acceleration in the first stage, the gears of the second gear are already in mesh. When the control unit transmits a step change command, the hydraulic drives of the gearbox release one clutch and clamp the second, making the transfer of torque from the motor from one step to another.
Thus, the process goes to the extreme stage. When reducing the speed and changing other conditions, the procedure is carried out in the reverse order. The change of steps occurs with the help of synchronizers.
The change of steps in the DSG box is carried out at a high speed, inaccessible even to professional racers.
What is mechatronics in automatic transmission
The control of both clutches and the change of steps is carried out using a control unit consisting of hydraulic and electronic units, sensors. This unit is called Mechatronic and is located in the gearbox housing.
Sensors built into the Mechatronic control the state of the gearbox and monitor the operation of the main parts and assemblies.
Parameters controlled by Mechatronics sensors:
- the number of revolutions at the input and output of the box;
- oil pressure;
- oil level;
- working fluid temperature;
- the location of the stage forks.
On the latest models of DSG boxes, ECT (electronic system that controls the change of steps) is installed.
In addition to the above parameters, ECT controls:
- vehicle speed;
- degree of throttle opening;
- motor temperature.
Reading these parameters prolongs the life of the gearbox and engine.
Types of Direct Shift Transmission
There are currently two types of DSG boxes:
- six-speed (DSG-6);
- seven-speed (DSG-7).
DSG 6
The first preselective (robotic) gearbox was a six-speed DSG, which was developed in 2003.
DSG-6 design:
- two clutches;
- two rows of steps;
- crankcase;
- Mechatronic;
- gearbox differential;
- main gear.
The DSG-6 uses two wet clutches that are invariably immersed in the transmission fluid to lubricate the mechanisms and cool the clutch discs, thereby extending the life of the transmission.
Two clutches transmit torque to the rows of gearbox steps. The drive disk of the gearbox is connected to the clutches by a flywheel of a special hub that combines the stages.
The main components of the Mechatronics (electro-hydraulic module) located in the gearbox housing:
- gearbox distribution spools;
- a multiplexer that generates control commands;
- solenoid and control valves of the gearbox.
When the position of the selector is changed, the gearbox distributors are switched on. The steps are changed with the help of electromagnetic valves, and the position of the friction clutches is corrected with the help of pressure valves. These valves are the "heart" of the gearbox, and the Mechatronic is the "brain".
The gearbox multiplexer controls the hydraulic cylinders, of which there are 8 pieces in such a gearbox, but no more than 4 gearbox valves operate simultaneously. Different cylinders operate in different gearbox modes, depending on the required stage.
Gears in the DSG-6 change cyclically. Two rows of steps are active at the same time, only one of them is not used - it is in standby mode. When changing the transmission torque, the second row is immediately activated, switching to the active mode. Such a mechanism of operation of the gearbox provides a gear change in less than a fraction of a second, while the movement of traffic occurs smoothly and evenly, without slowness and jerks.
DSG-6 is a more powerful robotic gearbox. The torque of a car engine with such a gearbox is about 350 Nm. Such a box weighs under 100 kilograms. Gear oil for DSG-6 requires more than 6 liters.
At the moment, DSG-6 is mainly installed on the following vehicles:
- Seat (Alhambra, Toledo);
- Skoda (Octavia, SuperB);
- Audi (TT, Q3, A3);
- Volkswagen (Tiguan, Golf, Jetta, Passat).
DSG boxes are equipped with Tiptronic, which transfers the box to manual control mode.
DSG 7
DSG-7 was developed in 2006 specifically for economy class cars. The DSG box weighs 70-75 kg. and contains less than 2 liters of oil. This gearbox is installed on budget cars with an engine torque of not more than 250 Nm.
To date, DSG-7 is mainly installed on the following cars:
- Audi (TT, Q3, A3);
- Seat (León, Ibiza, Altea);
- Skoda (Octavia, Fabia, SuperB);
- Volkswagen (Tiguan, Golf, Jetta, Passat).
The main difference between DSG-7 and DSG-6 is the presence of 2 dry clutch discs that are not in the transmission fluid. Such changes allowed to reduce fuel consumption, reduce the cost of service.
Advantages and disadvantages of a robotic automatic transmission
The robotic gearbox has its advantages and disadvantages in comparison with other transmissions.
Advantages of the DSG box:
- reduced consumption of the fuel mixture (up to 10-20%);
- the possibility of manual control, similar to manual transmission;
- no power loss when changing stages;
- smoothness of the car;
- high dynamic characteristics of a car equipped with a DSG box;
- reduction of the time required for acceleration;
- the possibility of automatic and manual gear selection;
- comfortable driving, equipped with such a gearbox;
- the absence of a clutch pedal and the usual selector lever, which does not cause difficulties when switching from a car with a classic automatic transmission;
Disadvantages of the DSG box:
- the high cost of a car with DSG compared to cars equipped with other types of transmissions;
- occasionally the robot slows down and does not keep up with the dynamic acceleration of the car, changing steps with a slight delay;
- mechatronics is one of the weak points in the DSG box, malfunctions periodically occur in this unit;
- if a malfunction occurs in mechatronics, it must be replaced, since it cannot be repaired;
- reduced gearbox resource;
- mechatronics malfunctions contribute to frequent temperature changes, which is especially important in winter;
- the service life of DSG-7 and its components is noticeably shorter than in DSG-6;
- increased box heating due to continuous preselector activity;
- increase in the cost of servicing a robotic gearbox;
- the complexity of repairing a robotic box, which not many service stations can carry out;
- not installed on SUVs and other powerful cars;
- the high cost of repairs, in some cases it is necessary to completely change the DSG.
Recommendations for the proper operation of a car equipped with a DSG gearbox, allowing you to extend the operational life:
- timely maintenance of the DSG gearbox (transmission fluid replacement according to the regulations - no more than 60000 kilometers, troubleshooting);
- warming up the robotic gearbox by briefly keeping the car in a standing position after starting;
- smooth movement after warming up for 1-5 kilometers from the moment the movement starts;
- avoidance of wheel slip;
- when stopping for more than 1 minute, it is recommended to switch the DSG box selector to neutral mode;
- when driving on snow and ice, it is recommended to turn on the “snowflake” mode, if available;
- with dynamic driving and fast accelerations, it is advisable to move the selector lever to the “sport” position;
- during each maintenance, it is necessary to diagnose the DSG box and perform initialization;
- the accelerator pedal must be depressed smoothly, even in manual mode;
- acceleration is desirable to carry out in manual mode, and smooth driving and braking - in automatic;
- parking the car from the DSG box to the parking lot in the “neutral” selector position with the mandatory inclusion of the parking brake (handbrake).
The robotic box is, in fact, an improved manual transmission, the switching of steps in which occurs using mechatronics based on various parameters read by the sensors. Subject to certain recommendations, you can significantly extend the life of the robotic box.
