15-12-2012, 06:07 PM
Torque Converter Clutches
1Torque Converter.ppt (Size: 1.08 MB / Downloads: 100)
Principle of Operation
A traditional torque converter is only approx. 90% efficient
The other 10% is converted into heat which must be dissipated by some type of cooler
Overdrive transmissions will commonly cause the engine RPM to stay below the coupling point of the torque converter
Lowers converter efficiency
More heat
A torque converter clutch is used to mechanically lock the turbine to the torque converter housing
This effectively locks the engine directly to the transmission input shaft
Eliminates slippage
Converter efficiency w/TCC applied = 100%
Less heat generated
Lower engine RPM at highway speed
Operation
Since the torque converter clutch is a direct mechanical coupling between the engine and transmission, there are certain times it should not be applied
Vehicle stopped – engine would kill
Low vehicle speeds – no torque multiplication
Acceleration - no torque multiplication
Deceleration (some) – engine braking would occur which would affect emissions
Components
Torque converter housing
The housing is the apply surface for the TCC clutch
Clutch assembly
Wet friction clutch
Release/Apply piston
Splined to turbine
Control system
Electrical solenoids
Apply valves
PWM (Pulse Width Modulated) TCC Control
On 96-99 4L60E transmissions GM used a pulse width modulated control system to apply the torque converter.
This system was designed to allow the clutch to slip on and slip off
Reduced the shift feel when the TCC was applied
Required the use of a high temperature material (woven carbon or Kevlar) to withstand the additional heat created by the slipping