Operation Section
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3.3 HP3 Type
(1) Construction and Characteristics
• The supply pump is primarily composed of the pump unit (eccentric cam, ring cam, two plungers), the SCV (suction
control valve), the fuel temperature sensor and the feed pump (trochoid type), and is actuated at 1/1 or 1/2 the engine
rotation.
• The two compact pump unit plungers are positioned symmetrically above and below on the outside of the ring cam.
• The fuel discharge quantity is controlled by the SCV, the same as for the HP2, in order to reduce the actuating load
and suppress the rise in fuel temperature. In addition, there are two types of HP3 SCV: the normally open type (the
suction valve opens when not energized) and the normally closed type (the suction valve is closed when not ener-
gized).
• With a DPNR system (Diesel Particulate NOx Reduction) system, there is also a flow damper. The purpose of this
flow damper is to automatically shut off the fuel if a leak occurs in the fuel addition valve passage within the DPNR.
Q000835E
Suction Valve
Plunger
Ring Cam SCV (Suction Control Valve)
Delivery Valve
Feed Pump
Fuel Temperature Sensor
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