The torque converter is often seen as the most complicated part in vehicles of today. It is, however, a very important component of automatic transmissions. This animation explains the theory behind this complex component.
Contents
1) Torque converter impeller
2) Blades and fluid of impeller
3) Centrifugal forces caused by rotation of impeller
4) Torque converter turbine
5) Fluid flow between impeller and turbine
6) Fluid coupling
7) Torque converter stator
8) Housing, lock-up clutch and shaft
9) Stages of operation: stall, acceleration, coupling
How Torque Converters Work
If you're familiar with manual transmissions, you know that an engine is connected to a transmission by way of a clutch. Without this connection, a car would not be able to come to a complete stop without killing the engine. Cars with automatic transmissions have no clutch that disconnects the transmission from the engine. Instead, they use a device called a torque converter. It may not look like much, but there are some very interesting things going on inside.
Turning a car's engine crankshaft produces torque (which is the energy you create by twisting something). Torque is what allows you to accelerate your car. The more torque an engine produces, the faster a car goes. A torque converter allows the engine in a car with an automatic transmission to keep running even as the wheels come to a stop.
In this article, we'll learn why automatic transmission cars need a torque converter, how a torque converter works as well as some of its benefits and shortcomings. The automatic gearboxes we refer to are the traditional type that have been popular in cars since about the 1950s. Newer types of automated transmission, like the semi-manual gearbox and CVT use other methods of power delivery, and don't include torque converters.
A torque converter is a type of fluid coupling, which allows the engine to spin somewhat independently of the transmission. If the engine is turning slowly, such as when the car is idling at a stoplight, the amount of torque passed through the torque converter is very small, so keeping the car still requires only a light pressure on the brake pedal.
If you were to step on the gas pedal while the car is stopped, you would have to press harder on the brake to keep the car from moving. This is because when you step on the gas, the engine speeds up and pumps more fluid into the torque converter, causing more torque to be transmitted to the wheels.
There are four components inside the very strong housing of the torque converter:
-impeller
-turbine
-stator
transmission fluid
The housing of the torque converter is bolted to the flywheel of the engine, so it turns at whatever speed the engine is running at. The fins that make up the pump of the torque converter are attached to the housing, so they also turn at the same speed as the engine. The cutaway below shows how everything is connected inside the torque converter.
The impeller inside a torque converter is a type of centrifugal pump. As it spins, fluid is flung to the outside, much as the spin cycle of a washing machine flings water and clothes to the outside of the wash tub. As fluid is flung to the outside, a vacuum is created that draws more fluid in at the center.
The fluid then enters the blades of the turbine, which is connected to the transmission. The turbine causes the transmission to spin, sending power through shafts, differentials, and out to the driving wheels. You can see in the graphic at left that the blades of the turbine are curved. This means that the fluid, which enters the turbine from the outside, has to change direction before it exits the center of the turbine. It is this directional change that causes the turbine to spin.
In order to change the direction of a moving object, you must apply a force to that object — it doesn't matter if the object is a car or a drop of fluid. And whatever applies the force that causes the object to turn must also feel that force, but in the opposite direction. So, as the turbine causes the fluid to change direction, the fluid causes the turbine to spin.
The fluid exits the turbine at the center, moving in a different direction than when it entered. The fluid exits the turbine moving opposite the direction that the pump (and engine) are turning. If the fluid were allowed to hit the pump, it would slow the engine down, wasting power. This is why a torque converter has a stator.
The torque converter is often seen as the most complicated part in vehicles of today. It is, however, a very important component of automatic transmissions. This animation explains the theory behind this complex component.
Contents
1) Torque converter impeller
2) Blades and fluid of impeller
3) Centrifugal forces caused by rotation of impeller
4) Torque converter turbine
5) Fluid flow between impeller and turbine
6) Fluid coupling
7) Torque converter stator
8) Housing, lock-up clutch and shaft
9) Stages of operation: stall, acceleration, coupling
How Torque Converters Work
If you're familiar with manual transmissions, you know that an engine is connected to a transmission by way of a clutch. Without this connection, a car would not be able to come to a complete stop without killing the engine. Cars with automatic transmissions have no clutch that disconnects the transmission from the engine. Instead, they use a device called a torque converter. It may not look like much, but there are some very interesting things going on inside.
Turning a car's engine crankshaft produces torque (which is the energy you create by twisting something). Torque is what allows you to accelerate your car. The more torque an engine produces, the faster a car goes. A torque converter allows the engine in a car with an automatic transmission to keep running even as the wheels come to a stop.
In this article, we'll learn why automatic transmission cars need a torque converter, how a torque converter works as well as some of its benefits and shortcomings. The automatic gearboxes we refer to are the traditional type that have been popular in cars since about the 1950s. Newer types of automated transmission, like the semi-manual gearbox and CVT use other methods of power delivery, and don't include torque converters.
A torque converter is a type of fluid coupling, which allows the engine to spin somewhat independently of the transmission. If the engine is turning slowly, such as when the car is idling at a stoplight, the amount of torque passed through the torque converter is very small, so keeping the car still requires only a light pressure on the brake pedal.
If you were to step on the gas pedal while the car is stopped, you would have to press harder on the brake to keep the car from moving. This is because when you step on the gas, the engine speeds up and pumps more fluid into the torque converter, causing more torque to be transmitted to the wheels.
There are four components inside the very strong housing of the torque converter:
-impeller
-turbine
-stator
transmission fluid
The housing of the torque converter is bolted to the flywheel of the engine, so it turns at whatever speed the engine is running at. The fins that make up the pump of the torque converter are attached to the housing, so they also turn at the same speed as the engine. The cutaway below shows how everything is connected inside the torque converter.
The impeller inside a torque converter is a type of centrifugal pump. As it spins, fluid is flung to the outside, much as the spin cycle of a washing machine flings water and clothes to the outside of the wash tub. As fluid is flung to the outside, a vacuum is created that draws more fluid in at the center.
The fluid then enters the blades of the turbine, which is connected to the transmission. The turbine causes the transmission to spin, sending power through shafts, differentials, and out to the driving wheels. You can see in the graphic at left that the blades of the turbine are curved. This means that the fluid, which enters the turbine from the outside, has to change direction before it exits the center of the turbine. It is this directional change that causes the turbine to spin.
In order to change the direction of a moving object, you must apply a force to that object — it doesn't matter if the object is a car or a drop of fluid. And whatever applies the force that causes the object to turn must also feel that force, but in the opposite direction. So, as the turbine causes the fluid to change direction, the fluid causes the turbine to spin.
The fluid exits the turbine at the center, moving in a different direction than when it entered. The fluid exits the turbine moving opposite the direction that the pump (and engine) are turning. If the fluid were allowed to hit the pump, it would slow the engine down, wasting power. This is why a torque converter has a stator.
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