Primary pressure regulation valve (page 3 of 5)

This strategy has been developed to satisfy the driver who normally expects the vehicle speed to increase when engine RPM increases.

To achieve this sensation, a plunger pushed by the selector cam (connects to the accelerator pedal) acts on the compensating piston via spring (9).

This mechanism inhibits immediate release of the oil pressure retaining the primary pulley (towards the retaining valve) when the accelerator pedal is suddenly pressed. Without this mechanism, the pressure release would instantaneously move the transmission control valve to the left.

If the primary chamber is empty of oil then the velocity change is also delayed. This allows the lubricating oil to achieve a constant flow rate into the chamber.

There is also a pressure retaining valve (ball type) in the outlet circuit of the transmission control valve, this prevents complete oil drainage of the primary pulley circuit.

1. ECVT control unit
2. Accelerator pedal switch
3. Throttle valve opening potentiometer
4. Switch, "D" position
5. Switch, "L" position
6. Switch, "R" position
7. Torque signal
8. Brake switch
9. Vehicle speed signal
10. Calculation during ratio changing
11. Calculation during rapid deceleration
12. Calculation during rapid acceleration
13. High and low pressure separation stage
14. Activation command for high pressure
15. Activation command for low pressure
16. Outlet control
17. Circuit pressure regulation solenoid-valve