During the operation of wheel loader, the initiator actively shuts down; when it starts again, the starter works normally, but the initiator cannot start, and a small amount of black smoke comes out of the exhaust pipe.
According to the relevant fault diagnosis procedures and previous repair experience in the repair manual of the aircraft, the maintenance personnel firstly put all the fuses in the fuse box of the aircraft, the engine throttle stepping motor action system, the engine stop motor action system and the engine fuel The supply system, and the atomization of the fuel injection nozzle and other related elements were thoroughly inspected, and no abnormalities were found. Further analysis believes that the initiation of the initiator cannot be related to the load of the initiator during the initiation process. Therefore, the cause of the problem is likely to be the host control circuit. The schematic diagram of the host control circuit is shown in the accompanying drawings.
After checking, when the initiator is initiated, the relays A, B, and C can be pulled in normally, and then the possibility that the initiator cannot be initiated due to the relay not being pulled in is excluded; then the electrical signals of the solenoid valves a and b are measured with a multimeter At the input end, it was found that no current was flowing, and the circuit 4 was closed at the moment. If no current is flowing, it can only mean that the power supply of the hydraulic pump and the valve controller is not connected. Upon further inspection, it was found that the 50A fusible joint D installed directly above the battery was fused due to a short circuit because the insulation function of the power supply line from the generator to the battery was not good. After the maintenance personnel insulated the line and replaced the fusible joint, when the initiator was launched again, the fault symptoms had disappeared.
When the key switch is in the "START" position, on the one hand, the power supply current through the circuit 1 causes the engine throttle stepper motor relay B and the hydraulic pump control relay C to pull in, and the relay C pulls in to make the valve controller of the hydraulic pump ( PVC) The circuit 5 connecting the hydraulic pump control solenoid valves a and b is connected; on the other hand, the power supply to the initiating controller (E, C) through circuit 2 to make it connect to the electric lake; in addition, the power supply current passes through circuit 3 The battery relay A is attracted, and then the power is supplied to the valve operator of the hydraulic pump through the circuit 4. When the power of the loader engine controller and the valve controller of the hydraulic pump are turned on, the two will jointly process the signals from multiple sensors on the engine, hydraulic pump and main control valve, and then control the hydraulic pump Solenoid valves a and b are used to determine the displacement of the internal spool, and then adjust the oil flow of the hydraulic pump into the main hydraulic pump servo system to change the swash plate skew angle of the main hydraulic pump to adjust the main hydraulic pressure. The displacement of the pump is used to match the launch of the engine.
