How a torque converter works
Before we learn how a torque converter works, we should first understand the torque converter and its function. The torque converter is installed right between the engine and the automatic transmission. The location is the same as the clutch position on a car with a manual transmission.
If a manual transmission uses a friction clutch, an automatic transmission uses a fluid coupling called a torque converter.
The torque converter function is slightly the same as a clutch; to connect or disconnect the engine power to the transmission. However, the torque converter is more complicated, and it works hydraulically by utilizing the Automatic Transmission Fluid oil power flow inside the torque converter.
So what are the torque converter functions in an automatic transmission? Here are some torque converter functions in automatic transmissions that we know:
- As an automatic clutch to transmit engine torque to the transmission input shaft using fluid.
- Reduces torsional vibration from the engine and drive train.
- Increases the engine torque.
- Evens out and smoothes engine vibrations.
I. Torque converter components
After we know the function of the torque converter in an automatic transmission, then the next thing we need to know before understanding how a torque converter works is to know what the components are in the torque converter.
Yes, many functions provided by a torque converter are a combination of the various components in the torque converter. There are at least 5 important components inside the torque converter, namely:
1. Pump impeller
The pump impeller is part of the torque converter. It is designed to be integrated with the torque converter cover. On the other hand, the torque converter cover is fastened to the engine flywheel using a few bolts—this resulting in the pump impeller rotation equal to the engine speed.
The pump impeller also consists of a vane and a guide ring designed like a concave bowl. That way, when the pump impeller rotates following the engine rotation, the concave bowl will throw out the ATF oil in it due to the centrifugal force.
The outburst of ATF oil due to the centrifugal force when the pump impeller works will produce kinetic energy used to turn the turbine runner.
2. Stator
The stator is a component of the torque converter placed right in the middle, between the pump impeller and the turbine runner. The stator functions to direct the flow of ATF oil that is ejected from the turbine runner so that it always hits the back wall of the vane pump impeller. As a result, there is an increase in power and torque on the pump impeller, which will also strengthen the turbine runner's rotation.
The stator also consists of a vane on which a one-way clutch is attached to the center axis. This one-way clutch prevents the stator from turning in the opposite direction when the pump impeller and turbine runner rotate at the same speed.
3. Turbine Runner
The turbine runner is a part of the torque converter connected directly to the input shaft of the automatic transmission. When the turbine runner rotates, the automatic transmission input shaft will also rotate.
This turbine runner's function is to convert the kinetic energy that occurs due to the burst of ATF oil from the impeller pump into mechanical energy (rotary motion) to rotate the transmission input shaft.
The turbine runner's shape also resembles a concave bowl filled with vane as in a pump impeller but is not tied to the torque converter cover. As for its location in the torque converter, the turbine runner floats in the middle and directly faces the pump impeller.
4. Damper Lock-up clutch assembly
The damper lock-up clutch assembly is basically the same as the friction clutch, placed right at the back of the turbine runner. The damper lock-up clutch functions to connect the turbine runner with the torque converter cover at a certain RPM. The damper lock-up clutch received the same rotation ratio between the flywheel rotation and the transmission input shaft.
5. Torque Converter Cover
Torque Converter Cover is the frame and overall torque converter body. This Torque Converter Cover functions as a place for the operation of the ATF oil fluid flow. The Torque Converter Cover also serves to prevent leakage when the fluid flows.
Torque Converter Cover is formed into one with the pump impeller and connected by several bolts to the engine's flywheel. That way, when the engine starts and rotates, the torque converter cover will also rotate.
Also read:II. The working principle of the torque converter
The torque converter has a working principle that utilizes power in the fluid flow (ATF oil). The torque converter's working principle is similar to the working principle that occurs in two fans that are installed side by side.
If two fans are placed close to each other and facing each other, then one of the fans is turned on, then the wind generated by the fan that turns on will move the other fan's fin. As a result, these two fans will rotate together.
The power flow that occurs in the fan above uses wind power generated by the fan that lights up. This working principle is also used in the torque converter but uses a different medium called Automatic Transmission Fluid oil.
III. How a torque converter works
The torque converter works hydraulically, which utilizes the power generated by fluid flow (ATF oil) due to the centrifugal force in the impeller pump. When the pump impeller rotates according to the engine speed, the ATF oil in the impeller pump will be ejected towards the turbine runner.
The floating turbine runner connected to the transmission input shaft will receive a strong burst of ATF oil. Then the ATF oil flow from the turbine runner flows back to the impeller pump.
At this time, the power is transferred from the engine to the transmission through the torque converter's ATF oil flow.
Inside the torque converter, the ATF oil always rotates in a coil spring forms. It rotates from the impeller pump to the turbine runner, and vice versa, and it will continue as long as the engine is running and rotating.
Due to the engine's constant dynamic and changing rotation, the torque converter must also keep up with these changes. But still, produce comfortable torque and moment and prevent damage to other transmission components.
Therefore, inside the torque converter, a stator is used to multiply the power by directing the flow of ATF oil ejected from the turbine runner. So that it always hits the back wall of the vane pump impeller. With this additional power, the turbine runner can rotate the wheel and move the car.
In addition to the stator, a damper clutch lock-up was added to compensate for the rotation in the turbine runner. With the damper lock-up clutch, the turbine rotation can be the same as the engine speed without requiring rotational power from the ATF oil flow. This condition generally occurs only at certain engine rpm to increase engine and transmission efficiency.