Secondary pressure regulating valve (page 2 of 2)

When the engine is operating under partial load conditions (approximately 60% of max power), the pressure control solenoid valve (6) acts, and hydraulic pressure is redirected from circuit (C) into chamber (D) via passage (E).

Since diameter D2 is greater than diameter D1, there is an increase of contact area that pushes the pressure regulating valve towards the right, therefore the circuit pressure is reduced. Alternatively, when the engine load is high, the solenoid valve (6) closes, excluding circuit (C) and chamber (D). The oil outlet is then connected, again via the solenoid valve (6).

This eliminates the force acting on the right side of the pressure regulating valve.

The contact area to push the regulating valve to the right is reduced, hence the circuit pressure increases.

The oil pressure is regulated as explained above.

In this way the optimum belt tension is ensured whilst minimising the power loss at the oil pump.

This control system gives better performance at low/medium engine loads and reduces fuel consumption.

1. Circuit pressure, kPa (bar, kg/cm², psi)
2. High pressure (solenoid valve inactive)
3. Low pressure (solenoid valve active)
4. Low speed
5. Pulley ratio
6. Overdrive