The truth behind automatic transmission cars
Functions of Trilok Converter
- Automatic torque conversion according to requirement to improve vehicle performance
- Almost doubles the engine torque during startup acceleration
- Efficient top gear-direct connection of engine to the transmission by use of lockup clutch
Internal Components
Working and fluid flow
- Impellor fluid flow ( Radially out) due to centrifugal force caused by engine rotation and fluid leaves impellor with radial as well as circumferential velocity
- Fluid flow from impeller to turbine , turbine to stator and stator to impeller back
The impeller receives input from the engine as its bolted with flywheel, by the rotation of impeller the fluid at the centre flows radially outwards due to centrifugal force and strikes the turbine blades and moves radially inwards on a turbine blades to generate simple fluid coupling .The fluid exits the turbine from interior and reaches back to impeller, but the direction of fluid is such that it opposes the motion of impeller. Hence the stator is imposed between the turbine and impeller .The stator is free to move in one side and restricted on other side due to action of one-way clutch. Hence the static stator whose blades are designed in such a away that it change the direction of fluid so that it aids the rotation of impeller.
Three phases of operation
1.When vehicles is stationary
2.When vehicle is acceleration, more torque requirement
3.When vehicle has less torque requirement
1 phase
Engine or impeller is rotating but turbine is stationary as the driver has to keep foot on brake pedal to keep vehicle stationary
2 phase:-acceleration
When the car is to be accelerated from the static, high starting torque and accelerating torque is required. Thus, the torque convertor ‘s main role comes into play .The stator plays vital role in this torque multiplication. As stator changes the direction of fluid continuously from turbine to impeller aiding impellers to increase speed which ultimately gives turbine enough torque to reach to the speed up to 90% of speed of impellor. Upto 10% is the friction losses of fluid coupling.
3 phase
When 90% speed is achieved, the stator begins to rotate. So to make torque converter much efficient this 10% loss is not affordable hence, lock-up clutch is introduced to connect engine directly to the transmission
Mathematically
M1=moment of impellor or pump wheel
M2=moment of turbine
M3=moment of stator or guide wheel
Then,
M1+M2+M3=0
M1=-(M2+M3)
Engagement of lock-up clutch
To increase the efficiency we remove the fluid coupling and directly engage the impellor with turbine by use of lock-up clutch. During the process of engagement at high speed the high impact applies on the clutch plate creating shock and noise,the damper are in the clutch plate to absorb this shock.
