In order to better protect the environment, nowadays excavators are more common in electronic fuel injection vehicles. The most direct advantage of electronic fuel injection engines is that they have better fuel efficiency, more flexible driving force, and higher ignition efficiency. To reduce the emission of harmful substances, it can meet the market demand of the industry that advocates energy saving and consumption reduction. Friends often come across all kinds of alarm codes, and most of these alarms are caused by common failures of sensors or relays. Hitachi excavator repaired and sorted out the specific locations and functions of some sensors and relays on some engines.
1. EGR valve
Function: EGR valve is a variable opening degree electromagnetic induction proportional valve controlled by ECU. Based on the information content of the engine speed ratio, temperature, and common rail working pressure, ECU makes a distinction, adjusts the opening degree of the EGR valve, so that appropriate organic exhaust gas enters the cylinder again, and the excess does not harm the driving force of the engine, but also reduces the exhaust The purpose of the water content of hydrocarbons.
2. Injector connector
Function: To maintain China Unicom of the intermediate control signal between the relay in the atomizing nozzle and the ECU. The ECU sends commands to the atomizing nozzle relay according to the received information such as the accelerator pedal sensor, speed ratio, temperature, and common rail working pressure to control the start and stop time of the spray. If the fuel supply is interrupted after the adjustment, it is very likely It will cause the accident to happen early and the target of the spurt, and then control the engine speed ratio and torque.
3. Common rail pressure sensor
Function: Used to feed back the high pressure diesel engine working pressure signal in the common rail cavity to the ECU. Because of the high pressure surge selected by the common rail diesel engine control system software, the working pressure of the surge is about 10 times higher than that of a general direct injection engine. Therefore, the ECU will monitor the working pressure of the diesel engine in the common rail cavity of the system in real time, and distinguish it based on the feedback working pressure signal and other feedback signals, and send command signals to the control modules such as the atomizing nozzle relay, EGR relay, and SCV valve.
4. CPU main speed sensor
Function: Used to feed back the engine speed ratio signal to the CPU. After the CPU receives the feedback signal from the main speed ratio sensor, it checks with the speed ratio set in the program flow to distinguish whether the engine speed ratio is normal and whether the engine load is normal, and integrates other feedback signals to make a check on the engine And related control of hydraulic transmission system. Under abnormal conditions, control the hydraulic transmission system to reduce horsepower or control the engine to shut down.
5. Add pressure sensor
Function: It is used to feed back to the ECU the breathing working pressure after the booster increases. After the ECU receives the feedback signal of the increased working pressure sensor, it can distinguish whether the intake system is normal. And integrate other feedback signals to control the engine's injection volume, EGR opening degree, SCV valve, etc. Under abnormal conditions, the engine will be controlled to reduce output.
6. SCV valve
Function: To control the total flow of diesel engine in the channel of the engine diesel fuel supply pump. The SCV valve is an inverse proportional electromagnetic induction proportional valve controlled by the ECU. The ECU receives signals such as engine speed ratio, temperature, common rail working pressure, and breathing working pressure, and exports the SCV valve to command the amount of current to control the opening of the SCV valve. The purpose of controlling the total flow of the diesel engine into the fuel supply pump and adjusting the working pressure of the common rail is exceeded. Abnormal phenomena can cause engine output to decrease or even shut down.
7. Engine main speed sensor
Function: The engine main and auxiliary speed ratio sensors are mutually used to feed back the engine speed ratio, engine crankshaft corner, and engine camshaft corner signals to the ECU so that the ECU can properly distinguish the timing information content. The two sensors are checked against each other. If a single sensor loses the feedback signal, the engine can still be used again with reduced output. If the two sensors additionally lose signals, the engine will not start.
8. Timing gear sensor
Function: The engine main and auxiliary speed ratio sensors are mutually used to feed back the engine speed ratio, engine crankshaft corner, and engine camshaft corner signals to the ECU so that the ECU can properly distinguish the timing information content. The two sensors are checked against each other. If a single sensor loses the feedback signal, the engine can still be used again with reduced output. If the two sensors additionally lose signals, the engine will not start.
