If the shut-off valve is not closed tightly, it is easy to cause diesel leakage and diesel generator flameout? The lax closing of the stop solenoid valve is one of the main reasons for the failure of the diesel engine. When the power is turned off with the key, the power to the solenoid valve solenoid is cut off. Close the solenoid valve to seal the oil passage from the fuel to the cylinder head; if the shutdown solenoid valve is not tightly closed, a small amount of fuel will continue to flow to the cylinder head oil passage, resulting in diesel generators that cannot be shut down. In addition to technological reasons, the shut-off solenoid valve is not tightly closed and is closely related to the cleanliness of the fuel. When the cleanliness of the fuel is low, impurities will invade the solenoid valve, pad the valve plate or block its movement, resulting in loose closing; during the maintenance process, ignoring the cleanliness of the oil circuit may also directly invade the impurities. 1. Failure phenomenon; A Cummins NT855 diesel generator injects a small amount of diesel from the exhaust pipe during a cold start. 2. Fault finding and analysis; Cummins NT855 diesel generator adopts PT pump oil supply system. The plunger movement of the injector drives the pushrod and rocker arm through the cam, allowing the injector to open and close periodically. However, when the engine is stopped, the cylinder’s fuel injectors may be in the open position. When there is more fuel in the bulldozer oil tank, the liquid level will be about 0.5m higher than the installation position of the injector, and the fuel system of the diesel generator PT pump is not equipped with a floating tank. After the diesel generator is turned off, the oil circuit is only cut off by the electromagnetic cut-off valve at the outlet of the PT pump and the one-way valve on the oil pipeline. After the diesel generator works for a period of time, due to the impurities in the diesel oil, the solenoid valve and the check valve are not closed tightly, so the diesel generator cannot work. When the diesel generator is not working, diesel fuel flows from the fuel tank into the cylinder through the filter, the PT pump solenoid shut-off valve, the check valve and the injector in the open position. While the flow is small, it’s enough to get the diesel spewing out of the exhaust on a cold start the next morning. 3. The influence of the failure of the solenoid valve is not tightly closed When the start switch is turned to the OFF position, the solenoid coil of the stop solenoid valve loses current and the suction force disappears. The valve plate of the shutdown solenoid valve closes the oil circuit under the thrust of the spring plate to shut down the engine. If the solenoid valve is not closed tightly, it will continue to supply fuel to the fuel channel, so that the oil pressure in front of the injector metering hole cannot be reduced to the flameout oil pressure in time, resulting in difficulty in flameout. If the solenoid valve is not closed tightly, the flameout time will be different, and the longest can be tens of seconds to several minutes. The lax closing of the shutdown solenoid valve is closely related to fuel cleanliness, except for manufacturing reasons. When the cleanliness of the fuel is low, impurities will invade the solenoid valve, pad the valve plate or block its movement, resulting in loose closing; during the maintenance process, ignoring the cleanliness of the oil circuit may also directly invade the impurities. When it is difficult to close because the solenoid valve is not closed tightly, it is usually possible to increase the throttle to hit the valve plates, so that one of the valve plates can close the oil circuit and immediately shut down the engine. 4. Troubleshooting; The method to eliminate the failure is to install a ball valve at the inlet of the PT pump, close the valve in time after get off work every day, and open the valve before cold start in the morning to prevent diesel injection from the exhaust pipe. When similar faults are found, they can be eliminated by cleaning the solenoid valve, but the most important thing is to improve the cleanliness of the fuel, otherwise the fault will happen again and again.
Post time: Sep-30-2022