wsm L3301 Workshop Manual page 146

L3301, L3901, L4701, WSM
Suction Control Valve (SCV)
The suction control valve (SCV) is a proportional control valve that adjusts the amount of fuel delivered from the
fuel pump to achieve the fuel pressure requested by the engine, has a function of delivering to the pressurizing part,
and is made up of a piston (5), cylinder (6), armature (3), and solenoid (2) etc.
The SCV is a linear solenoid type electromagnetic valve and the engine ECU controls the time the solenoid is
electrified (duty ratio control). When current flows through the solenoid, the armature moves based on the duty ratio
and pushes on the cylinder and fuel flow changes based on position of the cylinder enabling suitable fuel flow.
NOTE
• Linear solenoid type: when voltage is applied to the coil, the moveable core moves linearly in proportion
to the voltage based on the magnetic force
Pressurizing Part (Pump Body)
The pressurizing part (pump body) applies pressure
to the fuel supplied from the suction control valve, has a
function of supplying fuel to the rail, and is made up of an
IO valve (1), plunger (5), plunger barrel (6), spring (7),
tappet (8), and pump housing etc.
The engine side fuel camshaft (9) rotates and during
the lowering stroke, the spring cause the plunger to
lower. An optimal amount of fuel adjusted by the suction
control valve is suctioned through the IO valve and into
the plunger chamber (4).
Rotation continues and during the lift stroke of the
cam the plunger rises, pressurizes the fuel, and supplies
it through the IO valve to the rail.
(1) IO Valve
(2) Outlet Valve
(3) Inlet Valve
(4) Plunger Chamber
(5) Plunger
(6) Plunger Barrel
(7) Spring
1-M9
ENGINE
(1) Cylinder Part
(2) Solenoid
(3) Armature
(4) Discharge Port
(5) Piston
(6) Cylinder
(7) Suction Port
a: High Suction Volume
b: Low Suction Volume
c: ON
d: OFF
e: Large
f: Small
(A) To pressurizing section
(B) From fuel pump
[A] Suction Control Valve
[B] No delivery (current ON)
[C] When Solenoid is
Electrified
[D] Maximum delivery volume
(current OFF)
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(8) Tappet
(9) Fuel Camshaft
(A) From suction control valve
(B) To rail
[A] Suction Stroke
[B] Compression Stroke
9Y1211012ENM0013US0
KiSC issued 09, 2016 A