TORQUE CONVERTER IN TRACTORS

محول العزم فى محرك الجرار                                  TORQUE CONVERTER IN TRACTORS

 المعروفة باسم إسطوانة الزيت أو أسطوانة نقل الحركة من المحرك للجيربوكس أو الترانسميشن على زيت وليس ميكانيكا

 TORQUE CONVERTERS &  DRIVE PLATES

A. Powershuttle

B. Powershift

TORQUE CONVERTER -

The torque converter is mounted on the flywheel and transmits engine power to the transmission.

The unit contains 3 elements:-

1. Turbine - output member

2. Stator with free wheel clutch - Torque multiplication member

3. Pump or impeller - input member 

TORQUE CONVERTER COMPONENTS

A. Front View

B. Rear View

C Exploded View

1. Turbine - output member

2. Stator with free wheel clutch - Torque multiplication member

3. Pump or impeller - input member

4. Front Housing

TORQUE CONVERTER OPERATING PRINCIPLES -1

A.  Torque transmitted by a fluid

     The higher the velocity of the fluid, the greater the torque.

B. Transmission of torque by air flow between 2 fans.

A. Fluid Coupling consists of two bowls.

   The engine driven one on the left is called the pump or impeller.

   The output member on the right is called the turbine 

    Fluid level lies level with bowl at rest

B. Fluid Flow when bowl rotates.

  Fluid is thrown out if the bowl spins.

 Torque is transmitted to the upper bowl by the force of the fluid. 

This is a simple Fluid Coupling which will transmit torque as pump speed is increased, providing an automatic clutch with smooth engagement.

TORQUE CONVERTER OPERATING PRINCIPLES - 3

1. Pump or Impeller          2. Stator         3. Turbine

Torque converter has a third element called the stator.

The function of the stator is to redirect the oil returning from the turbine to the pump so it enters the pump vanes in the same direction as pump rotation.

This enables a torque converter to multiply the engine torque, the increase in torque is in proportion to the difference in speed between the pump and the turbine.

Therefore a torque converter is an automatic clutch which will increase torque in proportion to the load

TORQUE CONVERTER OPERATING PRINCIPLES - 4

The stator blades are curved, as C, and their effect is illustrated above by comparison of fluid spraying onto, A, a flat surface and, B, curved inlet surface.

The stator is mounted on a free wheel clutch which locks at low turbine speeds to provide torque multiplication, but turns when pump and turbine speed become the same.

TORQUE CONVERTER OPERATING PRINCIPLES - 5

A. Vortex Oil Flow

When the turbine is turning much slower than the pump, lower speed due to the loading, the internal oil is vortex flow, A, providing torque multiplication.

B. Vortex & Rotary Oil Flow

As the turbine speed increases, the oil flow  changes progressively to rotary flow.

C. Rotary Oil Flow

As the turbine speed increases to be equal to the pump speed, the oil flow changes rotary flow.  

Torque is transmitted but not multiplied.

TORQUE CONVERTER OPERATING PRINCIPLES - 6

P. Pump                  S. Stator - locked             T. Turbine

Directional oil flow from the turbine the turbine to the pump and return through the stator.

The turbine blades are designed to match engine power available.

STATOR OIL FLOWS

Oil flow returning from turbine to pump is redirected by the stator vanes to return to the impeller in the same direction as  rotation.

* At maximum torque multiplication, that is torque converter

(turbine) stall, return oil flow strikes the stator vanes at point A.

* As turbine speed increases and multiplication decreases, the return oil flow strikes the stator vanes progressively further inwards, B  to C.

* The stator is locked by the freewheel clutch

* As turbine speed approaches impeller speed the return oil flow strikes the back of the stator vanes, the freewheel clutch allows the stator to rotate with the impeller and turbine. 

STATOR FREE WHEEL CLUTCH

The stator clutch remains locked during torque multiplication, conditions A, B & C, when the turbine speed is less than pump speed.

The stator clutch allows the stator to freewheel and turn with the pump & turbine in condition D, when turbine speed approaches pump speed.  Torque is transmitted but not multiplied. 

TORQUE CONVERTER PERFORMANCE GRAPH

POWERSHUTLE TRANSMISSION

Illustrates relationship between turbine speed and torque multiplication.

Torque Converter Stall occurs when the load reduces turbine speed to Zero.

Torque converter ratio is the torque multiplication at stall, 2.38:1 means engine torque is multiplied by 2.38.