Land Rover Common Rail System Crs Denso Manual

Operation Section1–26
Fuel Discharge Quantity Control
• The diagram below shows that the suction starting timing (SCV (Suction Control Valve) ON) is constant (determined
by the pump speed) due to the crankshaft position sensor signal. For this reason, the fuel suction quantity is controlled
by changing the suction ending timing (SCV OFF). Hence, the suction quantity decreases when the SCV is turned
OFF early and the quantity increases when the SCV is turned OFF late.
• During the intake stroke, the...

Operation Section1–27
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...

Operation Section1–28
(2) Exploded View
Q000836E
Pump Housing
CamshaftEccentric CamRing CamFeed Pump
Plunger
Element Sub-AssemblySCV
 (Suction Control Valve) Regulating ValveFuel Temperature Sensor
Delivery Valve Delivery Valve Delivery Valve
Element Sub-Assembly
Plunger 

Operation Section1–29
(3) Component Part Functions
Feed Pump
• The trochoid type feed pump, which is integrated in the supply pump, draws fuel from the fuel tank and feeds it to the
two plungers via the fuel filter and the SCV (Suction Control Valve). The drive shaft actuates the outer/inner rotors of
the feed pump, thus causing the rotors to start rotating. In accordance with the space that increases and decreases
with the movement of the outer and inner rotors, the feed pump draws fuel into the suction...

Operation Section1–30
Suction Control Valve (SCV)
• In contrast to the HP2, the SCV for the HP3 supply pump is equipped with a linear solenoid valve. The fuel flow vol-
ume supplied to the high-pressure plunger is controlled by adjusting the engine ECU supplies power to the SCV (duty
ratio control). When current flows to the SCV, the internal armature moves according to the duty ratio. The armature
moves the needle valve, controlling the fuel flow volume according to the amount that the valve body fuel...

Operation Section1–31
Duty Ratio Control
- The engine ECU outputs sawtooth wave signals with a constant frequency. The value of the current is the effective
(average) value of these signals. As the effective value increases, the valve opening decreases, and as the effec-
tive value decreases, the valve opening increases.
When the SCV Energized Duration (Duty ON Time) is Short
- When the SCV energization time is short, the average current flowing through the solenoid is small. As a result, the
needle...

Operation Section1–32
When the SCV Energized Duration (Duty ON Time) is Long
- When the energization time is long, the average current flowing to the solenoid is large. As a result, the needle
valve is pressed out (in the compact SCV, the needle valve is pulled), creating a small valve opening. Subsequently,
the fuel suction quantity decreases.
Q002321E
Compact SCV
Needle ValveLarge
OpeningFeed Pump
Q002342E
Needle
Valve Small 
OpeningSCV
Feed Pump Conventional SCV 

Operation Section1–33
Q002322E
Small Valve
Opening Compact SCVNeedle ValveSCV
Feed Pump 

Operation Section1–34
Normally Closed Type
- When the solenoid is energized, the needle valve is pressed upon (in the compact SCV, the cylinder is pulled upon)
by the armature, completely opening the fuel passage and supplying fuel to the plunger. (Total quantity suctioned
→ Total quantity discharged)
- When power is removed from the solenoid, the return spring presses the needle valve back to the original position,
closing the fuel passage.
- The solenoid ON/OFF is actuated by duty ratio control. Fuel...

Operation Section1–35
When the SCV Energized Duration (Duty ON Time) is Long
- When the energization time is long, the average current flowing to the solenoid is large. As a result, the needle
valve is pushed out (in the compact SCV, the needle valve is pulled), creating a large valve opening. Subsequently,
the fuel suction quantity increases.
Q002344E
Needle
Va l v eLarge
Opening SCV Feed Pump Conventional SCV
Q002324 E
Large Valve
Opening
Compact SCV
Needle
Va l v eSCV
Feed Pump