Land Rover Common Rail System Crs Denso Manual
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Operation Section1–66 7. CONTROL SYSTEM 7.1 Fuel Injection Control (1) General Description • This system effects more appropriate control of the fuel injection quantity and injection timing than the mechanical governor or timer used in the conventional injection pump. The engine ECU performs the necessary calculations based on the signals that are received from the sensors located on the engine and the vehicle. Then, the ECU controls the timing and duration of the current that is applied to the injectors in order to obtain optimal injection timing and injection quantity. (2) Various Types of Fuel Injection Controls ControlFunctions Fuel Injection Quantity Control This control replaces the function of the governor in the conventional injection pump. It achieves optimal injection quantity by effecting control in accordance with the engine speed and accelerator opening signals. Fuel Injection Timing Control This control replaces the function of the timer in the conventional injection pump. It achieves optimal injection timing by effecting control in accordance with the engine speed and the injection quantity. Fuel Injection Rate Control (Pilot Injection Control)This function controls the ratio of the fuel quantity that is injected from the orifice of the injector within a given unit of time. Fuel Injection Pressure Control This control uses the rail pressure sensor to measure the fuel pressure, and it feeds this data to the engine ECU in order to control the pump discharge quantity.
Operation Section1–67 (3) Fuel Injection Quantity Control General Description • This control determines the fuel injection quantity by adding coolant temperature, fuel temperature, intake air temper- ature, and intake air pressure corrections to the basic injection quantity. The engine ECU calculates the basic injection quantity based on the engine operating conditions and driving conditions. Injection Quantity Calculation Method • The calculation consists of a comparison of the following two values: 1. The basic injection quantity that is obtained from the governor pattern, which is calculated from the accelerator position and the engine speed. 2. The injection quantity obtained by adding various types of corrections to the maximum injection quantity obtained from the engine speed. The lesser of the two injection quantities is used as the basis for the final injection quantity. Q000887E Engine SpeedEngine Speed Accelerator Opening Injection Quantity Injection Quantity Accelerator Opening Engine Speed Basic Injection Quantity Maximum Injection Quantity Low Quantity Side SelectedCorrected Final Injection QuantityInjector Actuation Period Calculation Individual Cylinder Correction Quantity Intake Air Pressure Correction Atmospheric Pressure Correction Cold Engine Maximum Injection Quantity Correction Ambient Temperature Correction Intake Air Temperature CorrectionSpeed Correction Injection Pressure Correction
Operation Section1–68 Set Injection Quantities • Basic Injection Quantity This quantity is determined by the engine speed and the accelerator opening. With the engine speed constant, if the accelerator opening increases, the injection quantity increases; with the accelerator opening constant, if the engine speed rises, the injection quantity decreases. • Starting Injection Quantity This is determined based on the basic injection quantity for when the engine starts up and the added corrections for the starter S/W ON time, the engine speed, and the coolant temperature. If the coolant temperature is low, the injec- tion quantity is increased. When the engine has completely started up, this mode is cancelled. • Injection Quantity for Maximum Speed Setting Determined by the engine speed. The injection quantity is restricted to prevent an excessive rise in engine speed (overrun). Basic Injection Quantity Engine Speed Accelerator OpeningQ000888E Injection QuantitySTA ON Time STA ON StartingStarting Base Injection QuantityCoolant Temperature High Low Q000889E Injection Quantity Engine Speed Injection Quantity for Maximum Speed SettingQ000890E
Operation Section1–69 • Maximum Injection Quantity This is determined based on the basic maximum injection quantity determined by the engine speed, and the added corrections for coolant temperature, fuel temperature, intake air temperature, atmospheric temperature, intake air pressure, atmospheric pressure, and full Q adjustment resistance (only for the 1st generation HP0 system), etc. Corrections • Cold Engine Maximum Injection Quantity Correction When the coolant temperature is low, whether during start-up or during normal operation, this correction increases the injection quantity. • Intake Air Pressure Correction When the intake air pressure is low, the maximum injection quantity is restricted in order to reduce the emission of black smoke. QB0717E Engine Speed Basic Maximum Injection Quantity Injection Quantity Engine SpeedQ000891E Q000892E Engine Speed Intake Air Pressure Correction Quantity Injection Quantity
Operation Section1–70 • Atmospheric Pressure Correction The maximum injection quantity is increased and decreased according to the atmospheric pressure. When the atmo- spheric pressure is high, the maximum injection quantity is increased. • Injection Quantity Delay Correction for Acceleration During acceleration, if there is a large change in the accelerator pedal opening, the injection quantity increase is de- layed in order to prevent black smoke emissions. • Full Q Adjustment Resistance (Only for 1st Generation HP0 Systems) The full Q resistance is for correcting the injection quantity for a full load. The maximum injection quantity is increased or decreased by the car manufacturer to match to standards. There are 15 types of full Q adjustment resistance. The appropriate one is selected and used. Q000893E Engine Speed Atmospheric Pressure Correction QuantityInjection Quantity Q000487E Time Change in Accelerator Pedal Position Injection Quantity After Correction Delay Injection Quantity +5V ECU VLQC A-GND Quantity Adjustment Resistor Correction Voltage Quantity Adjustment Correction Injection Quantity
Operation Section1–71 (4) Fuel Injection Rate Control • Although the injection rate increases with the adoption of high-pressure fuel injection, the ignition lag, which is the delay from the start of injection to the beginning of combustion, cannot be shortened to less than a certain period of time. Therefore, the quantity of fuel injected until ignition takes place increases (the initial injection rate is too high), resulting in explosive combustion simultaneous with ignition, and an increase in NOx and sound. To counteract this situation, pilot injection is provided to keep the initial injection at the minimum requirement rate, to dampen the primary explosive combustion, and to reduce NOx and noise. Q000895E Injection Rate Heat Release RateLarge First-Stage CombustionSmall First-Stage Combustion Crankshaft Angle (deg) Crankshaft Angle (deg)-20 TDC 20 40 -20 TDC 20 40[Ordinary Injection] [Pilot Injection]
Operation Section1–72 (5) Fuel Injection Timing Control • The fuel injection timing is controlled by the timing of the current applied to the injectors. After the main injection period is decided, the pilot injection and other injection timing is determined. Main Injection Timing - The basic injection timing is calculated from the engine speed (engine speed pulse) and the final injection quantity, to which various types of corrections are added in order to determine the optimal main injection timing. Pilot Injection Timing (Pilot Interval) - Pilot injection timing is controlled by adding a pilot interval value to the main injection. The pilot interval is calculated based on the final injection quantity, engine speed, coolant temperature, atmospheric temperature, and atmospher- ic pressure (map correction). The pilot interval at the time the engine is started is calculated from the coolant tem- perature and engine speed. Q000896E Actual Top Dead Center Pilot Injection Main Injection Pilot Injection Timing Pilot Interval Main Injection Timing 1. Outline of Injection Timing Control Timing 2. Injection Timing Calculation Method Engine Speed Injection Quantity Basic Injection TimingCorrectionMain Injection Timing Battery Voltage Correction Intake Air Pressure Correction Atmospheric Pressure Correction Intake Air Temperature Correction Coolant Temperature Correction Pilot IntervalBasic Injection TimingPilot Interval Engine SpeedBasic Injection Timing Pilot Injection Timing NE INJ lift1 0 Engine Speed Engine Speed Pulse Injector Solenoid Valve Control Pulse Nozzle Needle Lift
Operation Section1–73 Split Injection - The purpose of split injection is to improve the startability of a cold engine. Before the conventional main injection takes place, this function injects two or more extremely small injections of fuel. Multi-Injection Control (Only for Some Models) - Multi-injection control is when small injections (up to four times) are carried out before and after the main injection in accordance with the state of the main injection and engine operation. This interval (the time A-D in the diagram below) is based on the final injection quantity, engine speed, coolant temperature, and atmospheric pressure (map correction). The interval during start-up is based on the coolant temperature and engine speed. (6) Fuel Injection Pressure Control • The engine ECU calculates the fuel injection pressure, which is determined by the final injection quantity and the en- gine speed. The calculation is based on the coolant temperature and engine speed during start-up. Q000897E Main Injection Main Injection Pilot Injection Pilot InjectionPilot Injection Multi-Injection This is the same as conventional fuel injection. Before the main injection, a small quantity of fuel is injected. If the temperature is low when the engine starts, a small quantity of fuel is injected divided over multiple injections before the main injection. Pre-Injection Q000898E TDC A C D B TDC (G) Pulse Injection Rate Q000899EEngine SpeedFinal Injection Quantity Rail Pressure
Operation Section1–74 (7) Other Injection Quantity Control Idle Speed Control (ISC) System • The idle speed control system controls the idle speed by regulating the injection quantity in order to match the actual speed to the target speed calculated by the computer. The ISC can be automatic ISC or manual ISC. Automatic ISC - With automatic ISC, the engine ECU sets the target speed. The target engine speed varies with the type of trans- mission (automatic or manual), whether the air conditioner is ON or OFF, the shift position, and the coolant temper- ature. Idle Speed Control Conditions Conditions When Control Starts Conditions Affecting Control · Idle Switch · Accelerator Opening · Vehicle Speed· Water Temperature · Air Conditioning Load · Shift Position Engine ECU Target Engine Speed CalculationComparison Fuel injection Quantity CorrectionActual Engine Speed Actuators Fuel Injection Quantity Instruction Q000900E
Operation Section1–75 Manual ISC - The idle engine speed is controlled by the setting on the idle setting button at the drivers seat. Idle Vibration Reduction Control - This control reduces engine vibration during idle. To achieve smooth engine operation, it compares the angle speeds (times) of the cylinders and regulates injection quantity for each individual cylinder in the event of a large difference. ECU A-GND V-IMC A-VCC +5V IMC Volume Terminal Voltage Q000901E Target Engine Speed Q000902E t4 t3 t1#1 #3 #4 #1 #1 #3 #4 #2#3 #4 #2(Make the t for all the cylinders equal.) Angular Speed Crankshaft Angle Crankshaft AngleCorrection