Land Rover Common Rail System Crs Denso Manual
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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 Camshaft Eccentric Cam Q000845E Q000846E Ring Cam Eccentric Cam Camshaft
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. ElementCheck Ball SpringHolder Plunger Q000847E Resistance - Temperature Characteristic Temperature Resistance Value Thermistor Q000848E
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 Inject Rail Discharge ValveSuction Valve Plunger Return Spring Return Combustion Overflow Camshaft Fuel TankFuel Filter (With Priming Pump)SuctionFuel Intake Port Feed PumpRegulating Valve Suction Pressure Feed Pressure High Pressure Return Pressure
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 discharge quantity by the valve opening and enters the pump main unit. • The quantity of fuel adjusted by the SCV is pumped during the pumping stroke. SCV Plunger B Plunger AEccentric Cam Delivery Valve Suction Valve Ring Cam Plunger A: End of Compression Plunger B: End of Suction Plunger A: End of Suction Plunger B: End of Compression Plunger B: Start of Compression Plunger A: Start of Suction Plunger B: Start of Suction Plunger A: Start of Compression QD0707E
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 ad- dition, the fuel delivery capacity is 1.5 times that of the HP3. • The fuel discharge quantity is controlled by the SCV, the same as for the HP3. Q000850E Suction Valve Plunger Eccentric CamSCV (Suction Control Valve) Delivery Valve Feed PumpFuel Temperature Sensor
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 PartsFunctions Feed Pump Draws fuel from the fuel tank and feeds it to the plunger. Regulating Valve Regulates the pressure of the fuel in the supply pump. SCV (Suction Control Valve) Controls the quantity of fuel that is fed to the plungers. Pump UnitEccentric Cam Actuates the ring cam. Ring Cam Actuates the plunger. Plunger Moves reciprocally to draw and compress fuel. Suction Valve Prevents reverse flow of compressed fuel into the SCV. Delivery Valve Prevents reverse flow from the rail of the fuel pumped from the plunger. Fuel Temperature Sensor Detects the fuel temperature. Ring Cam Plunger Camshaft Eccentric Cam Q000851E
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 is controlled by the SCV. As with the HP3, the valve opening is adjusted by duty ratio control. The only difference from the HP3 is the shape of the pump unit. Operation and control are basically the same. For details on operation and control, see the explanation of the HP3. Q000853E Feed Pump from Fuel Tank (Suction) SCV from Feed Pump (Low Pressure) Pump Unit from SCV (Low-Pressure Adjustment Complete) From Pump Unit to Rail (High Pressure) From Fuel Ta n k To Rail Plunger Suction Valve Delivery ValveRing CamCamshaft SCV Feed Pump