Bosch Distributor Plunger Drive

By 29 March 2017

The rotary movement of the drive shaft is transferred to the distributor plunger via a coupling unit, whereby the dogs on cam plate and drive shaft engage with the recesses in the yoke, which is located between the end of the drive shaft and the cam plate. The cam plate is forced against the roller ring by a spring, and when it rotates the cam lobes riding on the ring’s rollers convert the purely rotational movement of the drive shaft into a rotating-reciprocating movement of the cam plate.

Pump assembly for generation and delivery of high pressure in the distributor-pump interior

The distributor plunger is held in the cam plate by its cylindrical fitting piece and is locked into position relative to the cam plate by a pin. The distributor plunger is forced upwards to its TDC position by the cams on the cam plate, and the two symmetrically arranged plunger return springs force it back down again to its BDC position.

The plunger-return springs abut at one end against the distributor head and at the other their force is directed to the plunger through a link element. These springs also prevent the cam plate jumping off the rollers during harsh acceleration. The lengths of the return springs are carefully matched to each other so that the plunger is not displaced from its centered position.

Pump assembly with distributor head
Generates the high pressure and distributes the fuel to the respective fuel injector.
1 Yoke, 2 Roller ring, 3 Cam plate, 4 Distributor-plunger foot, 5 Distributor plunger, 6 Link element,
7 Control collar, 8 Distributor-head flange, 9 Delivery-valve holder, 10 Plunger-return spring,
4…8 Distributor head.