Land Rover Common Rail System Crs Denso Manual

Operation Section1–36
When the SCV Energized Duration (Duty ON Time) is Short
- When the energization time is short, the average current flowing through the solenoid is small. As a result, the nee-
dle valve is returned to the original position by spring force, creating a small valve opening. Subsequently, the fuel
suction quantity decreases.
Q002345E
SCVFeed Pump
Small
Opening Needle
Va l v e Conventional SCV
Q002325E
Needle
Va l v e Small Valve
Opening Compact SCV
SCV
Feed Pump 

Operation Section1–37
Pump Unit (Eccentric Cam, Ring Cam, Plunger)
• The eccentric cam is attached to the camshaft and the ring cam is installed on the eccentric cam. There are two plung-
ers at positions symmetrical above and below the ring cam.
• Because the rotation of the camshaft makes the eccentric cam rotate eccentrically, the ring cam follows this and
moves up and down, and this moves the two plungers reciprocally. (The ring cam itself does not rotate.)
Plunger A
Ring Cam
Feed Pump
Plunger B...

Operation Section1–38
Delivery Valve
• The delivery valve for the HP3 has an integrated element and is made up of the check ball, spring, and holder. When
the pressure at the plunger exceeds the pressure in the rail, the check ball opens to discharge the fuel.
Fuel Temperature Sensor
• The fuel temperature sensor is installed on the fuel intake side and utilizes the characteristics of a thermistor in which
the electric resistance changes with the temperature in order to detect the fuel temperature....

Operation Section1–39
(4) Supply Pump Operation
Supply Pump Overall Fuel Flow
• The fuel is suctioned by the feed pump from the fuel tank and sent to the SCV. At this time, the regulating valve adjusts
the fuel pressure to below a certain level. The fuel sent from the feed pump has the required discharge quantity ad-
justed by the SCV, and enters the pump unit through the suction valve. The fuel pumped by the pump unit is pumped
through the delivery valve to the rail.
Filter
From Pump
To Rail
Q000849E...

Operation Section1–40
Operation
• The discharge quantity is controlled by SCV control, the same as for the HP2, however it differs from the HP2 in that
the valve opening is adjusted by duty ratio control.
• In the intake stroke, the spring makes the plunger follow the movement of the ring cam, so the plunger descends to-
gether with the ring cam. Thus, unlike the HP2, the plunger itself also suctions in fuel. When the suctioned fuel passes
through the SCV, the flow quantity is controlled to the required...

Operation Section1–41
3.4 HP4 Type
(1) Construction and Characteristics
• The HP4 basic supply pump construction is the same as for the HP3. The composition is also the same as the HP3,
being made up of the pump unit (eccentric cam, ring cam, plunger), the SCV (suction control valve), the fuel temper-
ature sensor, and the feed pump. The main difference is that there are three plungers.
• Because there are three plungers, they are positioned at intervals of 120? around the outside of the ring cam. In...

Operation Section1–42
(2) Exploded View
Q000457E
SCV
Fuel Temperature SensorFilter
Feed Pump
Regulating Valve
Pump Body
Ring Cam
Camshaft
IN
OUT 

Operation Section1–43
(3) Component Part Functions
• The HP4 supply pump component parts and functions are basically the same as for the HP3. The explanations below
only cover those points on which the HP4 differs from the HP3. For other parts, see the appropriate item in the expla-
nation of the HP3.
Pump Unit (Eccentric Cam, Ring Cam, Plunger)
• A triangular ring cam is installed on the eccentric cam on the drive shaft, and three plungers are installed to the ring
cam at intervals of 120°.
Component...

Operation Section1–44
• Because the rotation of the camshaft makes the eccentric cam rotate eccentrically, the ring cam follows this and this
moves the three plungers reciprocally. (The ring cam itself does not rotate.)
Plunger #1
Plunger #2
Eccentric CamCamshaft
Camshaft
Rotate 120  ClockwiseCamshaft
Rotate 120  Clockwise
Camshaft
Rotate 120  Clockwise
Ring Cam
Plunger #3
End of Pumping
End of Pumping
End of Pumping
Pumping
Pumping
Pumping
Suction
SuctionSuction
D000852E 

Operation Section1–45
(4) Supply Pump Operation
Supply Pump Overall Fuel Flow
• The fuel is suctioned by the feed pump from the fuel tank and sent to the SCV. At this time, the regulating valve adjusts
the fuel pressure to below a certain level. The fuel sent from the feed pump has the required discharge quantity ad-
justed by the SCV, and enters the pump unit through the suction valve. The fuel pumped by the pump unit is pumped
through the delivery valve to the rail.
Operation
• The discharge quantity...