1.3 MULTIJET 16V
(75 & 90 HP)
FIAT PUNTO TRAINING OUTLINE
Fiat Auto S.p.A.
After Sales Training
3.6.2 Bosch CP1 high-pressure pump (75 HP)
Features
The high-pressure pump is of the CP1 Compact type, with three radial pistons (radialjet). The
pump features a capacity of 567 mm3/rev, and a rotation speed equal to half the rotation
speed of the drive shaft (step-down ratio: 2:1) (owing to the pump being fitted onto the
camshaft through an Oldham coupling). The pump needs no timing; moreover, it is lubricated
and cooled by the fuel flow that runs through it: the necessary flow is supplied by the low-
pressure pump. The latter feeds the pump with a fuel amount that is always larger than the
engine needs, so as to make the fuel circulate back to the tank: by doing so, pump lubrication
and cooling will be achieved (the former taking priority over the latter).
Piston motion is obtained through a cam integral to the pump shaft: the latter actuates a
polygonal ring that acts on the piston foot.
Each pumping unit is equipped with a gate intake valve and a ball delivery valve.
The pump features a valve referred to as “shutoff valve", which makes it possible to protect the
pump in case of low flow rate from the low-pressure delivery, thus allowing the pumping units
and the eccentric mechanism to be lubricated.
1 Pressure pump
2 Oldham coupling for camshaft connection
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