Torque Converter, Basic Function - GF27.20-P-1000A
Model all with transmission 725
Automatic transmission with torque converter
Overview
This document contains information on:
- General
- Function
General
With a stationary vehicle and idle speed, the torque converter (2) reduces the power flow between the engine and the automatic transmission to a minimum. When driving off, it effects the engine torque increase as well as the stepless RPM and torque alignment.
The fuel consumption is reduced by using the torque converter (2) with integrated centrifugal pendulum. Changes in the control system area and the vibration absorption also help to achieve an increase in the service life of the torque converter components.
Torque converter power flow
Sectional view of torque converter
The impeller (4) is connected to the engine and the turbine wheel (3) is connected to the drive shaft (6). The stator (5) is connected to the transmission housing (1) via the overrunning clutch and stator shaft.
The oil in the torque converter (2) is continuously circulated so that heat generated during the operation phase can be dissipated via the oil cooler.
Function
The impeller (4) pumps the oil through the impeller blades outward to the turbine wheel (3) as a result of the centrifugal force and thus drives the turbine wheel. The turbine wheel blades direct the oil onto the blades of the stator, which in turn push the oil to the impeller (4). This deflection of the oil at the stator (5), which is supported against the transmission housing by the overrunning clutch, induces an increase in torque.
Torque conversion is at its maximum value in the stall point, with rotating impeller (4) and stationary turbine wheel (3).
During the acceleration phase, the rotational speed of the turbine wheel (3) increasingly converges with the rotational speed of the impeller (4), meaning that the RPM difference grows smaller until the rotational speed at the coupling point is almost equal. Once the coupling point has been reached, the stator (5) rotates freely.