Fiat 1996 Brava Service Manual page 392

Bravo-Brava ^
TD100
Engine
Fuel system
10.
Supercharging control valve
The function of the supercharging control valve is to adjust the value of the maximum fuel flow rate ac­
cording 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 sup­
plementary 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 super­
charging pressure
8. Discharge of the transfer
pressure
9. Recovery connector
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tX-96 - Cancels and replaces
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