Injection Actuation System-continued

TM 9-2320-312-24-2

Systems Operation Section

The high pressure oil passage connects with each

The injection actuation system serves two functions.

unit injector bore in order to supply high pressure

The injection actuation system supplies high

actuation oil to unit injectors (7). Actuation oil that

pressure oil in order to power HEUI injectors (7).

is under high pressure flows from unit injector

Also, the injection actuation system controls the

hydraulic pump (1) through the cylinder head to all

injection pressure that is produced by the unit

of the injectors. Oil is contained in the high pressure

injectors by changing the actuation pressure of the

oil passage until the oil is used by the unit injectors.

oil.

Oil that has been exhausted by the unit injectors is

expelled under the valve covers. This oil returns to

The injection actuation system consists of five basic

the crankcase through oil drain holes in the cylinder

components:

head.

Engine oil pump (4)

Engine oil filter (3)

Unit injector hydraulic pump (1)

Injection actuation pressure control valve (IAP

Control Valve) (10)

Injection actuation pressure sensor (IAP Sensor)

(6)

Oil from engine oil pump (4) supplies the needs

of the engine lubrication system. Also, oil from the

engine oil pump supplies the needs of unit injector

hydraulic pump (1) for the fuel system. The capacity

of the engine oil pump has been increased in order

to meet the additional flow requirement that is

necessary.

Oil that is drawn from the sump is pressurized

to the lubrication system oil pressure by engine

oil pump (4). Oil flows from the engine oil pump

through engine oil cooler (5), through engine oil

filter (3), and then to the main oil gallery. A separate

circuit from the main oil gallery directs a portion of

the lubrication oil in order to supply unit injector

hydraulic pump (1). A steel tube on the left side of

the engine connects the main oil gallery with the

inlet port of the unit injector hydraulic pump.

Oil flows into the inlet port of unit injector hydraulic

pump (1) and the oil fills the pump reservoir. The

pump reservoir provides oil to the unit injector

hydraulic pump during start-up. Also, the pump

reservoir provides oil to the unit injector hydraulic

pump until the engine oil pump can increase

pressure.

The pump reservoir also provides makeup oil to

the high pressure oil passage in the cylinder head.

When the engine is off and the engine cools down,

the oil shrinks. A check valve in the pump allows

oil to be drawn from the pump reservoir in order to

keep the high pressure oil passage full.

Oil from the pump reservoir is pressurized in unit

injector hydraulic pump (1) and the oil is pushed out

of the outlet port of the pump under high pressure.

Oil then flows from the outlet port of the unit injector

hydraulic pump to the high pressure oil passage in

the cylinder head.