High pressure supply valves (page 2 of 3)

The function of the supercharging control valve is to adjust the value of the maximum fuel flow rate according to the variations in the pressure of the intake air created by the turbocharger.

The supercharging control valve is composed of a valve body (1) which contains a piston (2) which rests on a spacer (3).

There are two different size diaphragms (4) at each side of the spacer (3).

The supercharging pressure, produced by the turbocharger, enters between the two diaphragms via the connector (7).

The supercharging valve is fitted in the transfer pressure circuit somewhere between the transfer pump and the supplementary flow rate device.

It varies the pressure acting on the supplementary device pistons according to the pressure of the air supplied by the turbocharger.

On accelerating the engine speed increases and consequently so too does the pressure produced by the turbocharger which reaches the supercharing control valve gradually moving the diaphragms (4) which compress the spring (5).

The valve piston (2) moves opening the discharge port (8) producing a drop in pressure behind the supplementary flow rate device pistons.

Under these circumstances the supplementary device spring can gradually thrust the system towards the "supplement engaged" position.

This movement allows the control valve piston (2) to gradually open a port (8) which allows the fuel to be discharged via the diesel return pipes to the vehicle tank and makes it possible to reduce the pressure which builds up upstream of the supplementary device pistons.

1. Valve body
2. Piston
3. Spacer
4. Diaphragms
5. Spring
6. Adjustment screw
7. Connector for the supercharging pressure
8. Discharge of the transfer pressure
9. Recovery connector