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Torque Converter Drive

From RitchieWiki

Mechanical Features and Designs

A torque converter drive is a type of fluid coupling turbine that transmits power from a driving device such as an engine or an electric motor to a driven device such as a transmission. Using hydraulic action, it allows the load to be disconnected from the power source without the use of a mechanical clutch.[1]

Typically, engines are connected to a transmission via mechanical clutch, as this is the component that enables the vehicle to stop without stalling the engine. Some vehicles, however, operate with an automatic transmission that relies on a torque converter to stop the engine without having to disconnect it from the transmission. This is a necessary function in cars and other types of vehicles because it allows the engine to continue turning while the movement of the gears and wheels are static.

Because the torque converter is a type of fluid coupling, the rotation of the engine occurs independently from that of the transmission. The amount of torque that passes through is determined by the rotation of the engine. If the movement of the vehicle is slow or stopping, the torque will release smaller amounts of fluid.

A torque converter is made up of a series of components including a pump, a turbine, a stator, and transmission fluid. The frame of the converter is bolted onto the engine’s flywheel, which makes it run at the same speed as the engine. The centrifugal pump consists of fin-like blades that draw fluid to the outside before it is sucked back to the center in a vacuum-like manner. The fluid enters from the outside and the nature of the blades change the direction of the fluid by the time it reaches the center. This change of direction creates a force that, once exerted, causes the transmission to spin, a movement consistent with that of a vehicle.

The stator, which is positioned in the torque’s center, is responsible for preventing the fluid from entering the pump, a cycle that would slow down the engine and waste power. The stator consists of a one-way clutch and a unique blade design that forces the fluid to spin while the stator remains still. The stator only applies when the vehicle is not moving. When it is moving, both the pump and the turbine are moving at approximately the same speed, so the stator is not needed.

The torque converter is successful in that it not only enables the vehicle to achieve a complete stop without stalling the engine, but it also provides more torque for the engine when it picks up speed after stopping.

One of the drawbacks, however, is that the transmission doesn’t move at the exact speed of the engine, a factor resulting in the loss of power. This can considerably affect the gas mileage that some vehicles receive from their transmissions. The torque operates a clutch to lock up the two halves of the converter to try and counter this loss of power.[2]

[edit] References

  1. Glossary. About.com. 2008-09-30.
  2. Glossary. About.com. 2008-09-30.