GTE (torque converter) is a device that converts and transmits torque from the internal combustion engine to the driven shafts of the gearbox. In this case, the change in torque and speed is stepless.
As a rule, the torque converter (from the English torque converter) in the vehicle transmission device is used on cars with an automatic transmission or CVT gearbox.
Hydraulic converter: device and principle of operation
Gas turbine engine includes the following details:
- Pump wheel;
- Reactor (stator);
- Turbine wheel;
- Locking mechanism;
These parts are contained in a single strong and sealed housing, which is usually attached to the flywheel of the internal combustion engine. Also, the torque converter is filled with ATF working transmission fluid, and during operation, the oil noticeably heats up and mixes inside the gas turbine engine.
An impeller is rigidly attached to the converter housing, which rotates from the engine shaft and creates transmission fluid flows inside the converter. These flows, in turn, rotate the reactor, as well as the turbine wheel. In this case, a gas turbine engine differs from a conventional fluid coupling precisely by the presence of a reactor.
The reactor (aka stator) is connected to the impeller utilizing an overrunning clutch. This connection makes it possible to achieve the fact that if the pump’s speed and the turbine are very different, then the reactor is automatically blocked.
Blocking the stator allows more working transmission fluid to be transferred to the impeller. The presence of a reactor in the device of the gas turbine engine allows you to increase the torque by 3 times during the acceleration of a car with automatic transmission. The turbine is connected to the gearbox shaft; the connection is rigid.
It is important to understand that the torque transmission inside the converter occurs without a direct connection of the individual components; that is, the torque is transmitted through the fluid.
This means that shock loads are minimized, a car with a torque converter accelerates smoothly from the start, there are no jerks, and then, while driving, gear changes are smooth.
However, this solution also has certain disadvantages. Increased heating often occurs inside the gas turbine. Such an increase in temperature occurs because the turbine wheel slips relative to the pump wheel since, in most operating modes, the torque of the turbine and pump wheels are not equal.
The result of slippage is significant heat generation, reduced transmission efficiency and increased fuel consumption. At the same time, to reduce fuel consumption, a torque converter lock is used, which is implemented using a gas turbine engine lock mechanism.
The gas turbine blocking mechanism
The specified locking mechanism provides the possibility of a rigid connection between the pump and the turbine. If the torque converter is blocked, the automatic transmission works in such a mode when the engine and transmission are rigidly connected. The transfer of torque from the internal combustion engine to the automatic transmission occurs without losses.
Blocking of the gas turbine engine in the Box – an electronically controlled automatic machine works so that the signal to turn on the locking mechanism comes from the ECU by the gearbox; the lock itself is turned on according to a given algorithm prescribed in the program.
At the initial stage, many “automatic machines” initiated the torque converter lockup only when the car accelerated to a certain speed (above 60-70 km / h). More modern automatic transmissions block the torque converter at low speeds (from 20 km / h).
As a result, fuel savings are achieved in highway driving mode and in the city, where the driving speed is usually low. A still locked torque converter allows the engine braking effect on the automatic transmission at a certain speed.
To put it simply, the ECU engine stops the supply of fuel to the cylinders at the moment when the torque converter lock-up is triggered. At this time, the engine shaft continues to rotate due to the car’s movement “coasting” and not due to the receipt of energy from the combustion of fuel in the cylinders.
It would seem that blocking the torque converter makes it possible to improve the characteristics of this type of transmission, achieve fuel efficiency, increase efficiency, etc. On the one hand, this is so; however, the rigid connection of the internal combustion engine and the box by blocking the gas turbine engine also means that shock loads begin to be transmitted to the motto and transmission.
As a result, the resource of the automatic transmission decreases since the inclusion of the locking mechanism increases the load and wears out the automatic transmission clutches faster. Also, the transmission oil’s rapid contamination; gears with a blocked torque converter do not turn on so smoothly.
What is the bottom line?
As you can see, the torque converter is actually a separate unit, taken out of the body of the automatic transmission itself. In this case, the normal operation of the hydromechanical gearbox without a torque converter (torque converter) is impossible. For this reason, the automatic transmission and gas turbine engine assembly is usually called “automatic transmission”, that is, without separating these units.
Finally, we note that even taking into account the strength of the case, high loads on the torque converter (including temperature ones) can disable this element. As a result, the torque converter starts to leak, and malfunctions of the device’s internal components occur.
Because the cost of torque converters for different models of automatic transmissions is quite high, many qualified service stations for the repair of automatic transmissions repair torque converters. During the repair process, the gas turbine engine is disassembled, worn elements are replaced, and the body is welded to restore tightness.