What is a Torque Converter?
The torque converter both transmits and multiplies the torque from the engine using the ATF (Automatic Transaxle Fluid) into the transaxle (planetary gear unit) as the medium.
The torque converter consists of the pump impeller, turbine runner, one-way clutch and stator, and the converter case which contains all of these components. The converter is filled with the ATF, which is supplied by the oil pump. The engine rotates and the pump impeller rotates, then this fluid is forced out from the pump impeller in a powerful stream that rotates the turbine runner.
HINT:
For ATF, DEXRONII or Toyota type T-IV is used.
Construction Pump Impeller
The pump impeller is integrated with the converter case and is connected to the crankshaft via the drive plate. Many curved vanes are mounted on the inside of the pump impeller. A guide ring is installed on the inner edges of the vanes to provide a path for smooth fluid flow.
Turbine Runner
Many vanes are installed in the turbine runner, as in the pump impeller. The direction of the curvature of these vanes is opposite from that of the pump impeller vanes. The turbine runner is installed on the transaxle input shaft so that the vanes inside it oppose pump impeller vanes with a very small gap in between.
HINT:
The turbine runner rotates with the transaxle input shaft when the vehicle is running with the shift lever position in the “D”, “2″, “L” or “R” range. However, it is stopped rotating when the vehicle is stopped. When the shift lever position is in the “P” or “N” range, the turbine runner rotates freely with the rotation of the pump impeller.
Stator
The stator is located between the pump impeller and the turbine runner. It is mounted, via a one-way clutch on the stator shaft, which is fixed to the transaxle case.
1. Stator operation
The flow of the fluid returning from the turbine runner to the pump impeller is in the direction that impedes the rotation of the pump impeller. Therefore, the stator changes the direction of fluid flow so that it strikes the back of the vanes of the pump impeller, giving the pump impeller an added “boost” and thus increasing torque.
2. One-way clutch operation
The one-way clutch allows the stator to rotate in the same direction as the engine crankshaft. However, if the stator would start to rotate in the reverse direction, the one-way clutch locks the stator in order to prevent it from rotating.
