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Tất cả tài liệu về bơm ECD-V (tài liệu đào tạo của Denso ECD): -Composition and Construction of ECD-V3 Pump System -Determining the Injection Timing -ECD-V Series -ECD-V4 Outline -ntake Restriction Control -Outline of Injection Ti
9SERVICE TECH Vol.467 03-8 This session describes the construction and operation of products (sensors) associated with the inputsignal of the ECD system. This sensor is installed on the venturi (intake) and moves in unison with the main valve in order to detect the throttleposition. The sensor is constructed with a variable resistor to detect the throttle position and a contact point to detectthe idle position. Along with the speed sensor, it is one of the main sensors used for calculating the basic injectionvolume. This is an electromagnetic sensor for detecting the cam angle of the injectionpump. There is a magnet and a coil inside the sensor, and as the pulsar rotates,the magnetic flux that passes through the coil increases, generating analternating current. The pulsar is constructed of 56 teeth, with 4 toothlesssections each the size of 2 teeth. The pulsar rotates once for every 2 rotationsof the engine, generating a cam angle pulse at the electromagnetic sensor.From the number of these pulses and the interval between them, the engineECU calculates the cam angle and the engine speed. The speed sensor, along with the throttle position sensor and the acceleratorsensor, is one of the main sensors used for calculating the basic injectionvolume.11Speed SensorSpeed SensorConnectorSpeed SensorToothless SectionRoller RingMagnetPulsarCoilPulsarSpeed Sensor0+-TimeOutputVoltageSensor Output Signal22Throttle Position SensorThrottle Position Sensor 10SERVICE TECH Vol.467 03-8 The sensor is constructed with a resistor and a moving contact point in order to convert the position of the mainvalve into a voltage value. The engine ECU supplies 5V to the VC terminal. Because the sensor moves in unisonwith the main valve, when the moving contact point moves, a voltage proportionate to the throttle position is outputfrom the VA terminal. In some systems, the venturi (throttle valve) does not work in unison with the accelerator pedal. These systems usean accelerator sensor that is installed on the accelerator pedal and directly detects the accelerator position. Thissensor uses a hall element that reacts to magnetic force to generate electromotive force. It is a non-contact type usinga dual system with two internal electric circuits, increasing durability and reliability. Along with the speed sensor, it isone of the main sensors used for calculating the basic injection volume. The idle condition is detected by whether the contactpoint is on or off. The contact point closes when the mainvalve is fully closed (idling), which generates continuitybetween the IDL terminal and E2. When not idle, thecontact point is open. The engine ECU judges whetheror not the engine is idling, and corrects the idle speedcontrol and the acceleration rate.2-1 Throttle Position Detection2-2 Idle Position Detection33Accelerator Sensor SERVICE TECH Vol.467 03-811 This sensor detects the air pressure inside the intake manifold and sends a voltage signal to the engine ECU. It is asemi conductor pressure sensor, with internal crystals (silicone chips) that change their electrical resistance whenpressure is increased. The intake air pressure (absolute pressure) is converted into an electrical signal and amplified.It is sent to the engine ECU, where the intake air volume is calculated. The output voltage increases during thecharging boost of the turbo charger, in order to increase the injection volume. The coolant temperature sensor is installed on the engine cylinder block to detect the temperature of the enginecoolant. The sensor uses a thermistor, the resistance of which varies according to the temperature. The temperaturevariation is converted into a resistance variation, which is detected. As the temperature increases, the resistance ofthe thermistor decreases. When the coolant temperature is low, the injection volume is increased and the injectiontiming is advanced. The intake air temperature sensor is installed inside the air cleaner to detect the temperature of the intake air. Thesensor uses the same type of thermistor as the coolant temperature sensor. The density of the air varies withtemperature, so the injection volume is corrected. The fuel temperature sensor is installed on the injection pump. It detects the temperature of the fuel and sends theinformation to the engine ECU. It uses the same type of thermistor as the coolant temperature sensor. The viscosityof the fuel varies with temperature, so the injection volume is corrected.44Intake Air Pressure Sensor55Coolant Temperature Sensor and Intake Air Temperature Sensor66Fuel Temperature Sensor 12SERVICE TECH Vol.467 03-8 A resistor molded from plastic or a ROM is installed on the side of the injection pump. The engine ECU reads thedata from the resistor or ROM to calculate the fuel injection volume. There are 31 types of resistors with differentresistance values, so the most appropriate one is used. The ROM type can store over 10 data points dealing with the engine speed and the accelerator position. This enableshigh accuracy fuel injection control whatever the engine conditions, which lowers exhaust gas emissions. The ROMcan be modified when adjusting the pump, so that during normal driving a fixed value is input to the engine ECU.77Correction Resistor and Correction ROM . injectionvolume.1 1Speed SensorSpeed SensorConnectorSpeed SensorToothless SectionRoller RingMagnetPulsarCoilPulsarSpeed Sensor0 +-TimeOutputVoltageSensor Output Signal22Throttle. angle and the engine speed. The speed sensor, along with the throttle position sensor and the acceleratorsensor, is one of the main sensors used for calculating