Diesel pressure pump

Description 1060E

1.9 JTD 8V

PRESSURE PUMP

Construction features

It is the "radialjet" type with three radial pistons (total capacity 0.657 cc) and is driven by the timing belt without requiring synchronization.

Each pumping unit consists of:

• a piston (5) operated by a cam (2) fixed to the pump (6) shaft
• an inlet valve (3)
• a supply ball valve (4).

1, Cylinder

2, Cam

3, Inlet valve

4, Supply ball valve

5, Piston

6, Pump shaft

7, Inlet - low pressure (from the diesel filter)

8, Supply - high pressure (rail)

9, Supply - low pressure (recirculation)

Operation

The UNIJET system pump, called Radialjet because it has radial pistons, is driven, without needing to be synchronized with the engine, at a rotation speed which is half the engine speed, for reasons of suitability (retrofit to traditional system).

The movement of the pistons is determined by a cam joined to the pump shaft, with a rocker lever between the piston foot and the cam.

Each pumping unit has an inlet plate valve and a delivery supply valve.

The pump is lubricated and cooled by the same diesel circulating inside, through suitable ducts.

To adjust the delivery pressure, a pressure-regulating solenoid, also called the pressure regulator, is mounted on the pump.

The pump should be supplied at low pressure with a pressure of at least 0.5 bar, with a minimum flow rate of 0.5 l/min. higher than the supply, to ensure correct pump cooling.

The fuel drawn off by the pressure regulating valve and the fuel used for cooling and lubrication of the pump are sent to the tank at atmospheric pressure.

1, Fitting flange

2, Pump shaft

3, Tappet

4, Spring

5, Cylinder

6, Piston

7, Inlet valve

8, Head

9, Supply valve

10, Cam

11, Bearings

PRESSURE REGULATOR

Construction features

It is mounted on the pressure pump and controlled by the fuel injection control unit. It regulates the pressure of the fuel supply to the injectors.

Composition

The pressure regulator consists of:

• a spherical shutter (1)
• a valve (3) control pin (2)
• a pre-loading spring (4)
• a coil (5).

1, Spherical shutter

2, Pin

3, Valve

4, Pre-loading spring

5, Coil

6, Casing

7, Keeper

Operation

With the solenoid de-energized, the delivery pressure depends on the spring preload (about 150 bar at 1000 pump rpm); adjustment shims may be used to adjust the preload to the desired value.

Pressure modulation is obtained by supplying the solenoid coil in PWM (Pulse Width Modulation) and closing the regulation loop by means of the feedback from the pressure signal; the PWM signal has a carrier of 200 Hz and the duty cycle may be varied via software from 1% to 95%. The regulator is not replaced by itself, the complete pump is replaced.

1, High pressure outlet

2, Pressure regulator

3, Return (to the tank)

4, Inlet (from the filter)

RAIL

The high-pressure diesel accumulation manifold (rail) dampens the pressure fluctuations caused by the three pump strokes occurring at each pump revolution and by the opening of the injectors.

The internal volume of the rail has been designed to dampen these pulsations, without allowing delays in pressure adaptation during transitory moments and without hindering the starting stage, when the rail must fill with diesel.

The rail, made of steel to withstand the high operating pressures, is very long in shape, and comprises a cylindrical cavity with a diameter of 11 mm running along the entire length of the rail; the volume of the cavity is about 34 cc

There are through holes for securing the rail to the engine by means of brackets.