Treatment of engine runaway accident in the hottes

2022-08-18
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Treatment of engine runaway accident in construction machinery

in the practice of mechanical maintenance, it is often encountered that the diesel engine is stuck in the maximum oil supply position due to the speed regulating rack or ring gear of the high-pressure oil pump, or the governor loses the speed regulating characteristics due to various reasons, and other fuels enter the cylinder, especially when the engine is started at the same time, or the gear is shifted, the load is removed, etc., the engine has runaway fault

after speeding, if emergency measures are taken to apply for three provincial key projects of technological innovation, such as blocking the intake pipe, pulling the pressure reducing handle to the pressure reducing position, using the exhaust brake, quickly loosening the high-pressure oil pipe of each cylinder to stop oil supply, the speeding accident can be stopped. If measures are not taken in time after speeding, the engine will overspeed for a long time, which may lead to vicious accidents such as connecting rod bolt breaking and body breaking. It may also cause the governor flyweight or steel ball to fall off, collide or break the governor housing. The rotation of the camshaft of the fuel injection pump is limited, the oil pump will no longer supply oil, and the engine will automatically shut down

in the runaway fault in which the governor housing is broken, in addition to the routine correction of the fuel injection pump, the connection reliability of the moving parts of the engine and the bending deformation of the valve mechanism rod, it is also necessary to readjust the fuel supply timing. Because the experimental machine 1 is generally 60 tons or 100 tons, when the flying hammer is thrown off and stuck, the camshaft of the fuel injection pump is forced to stop by the flying hammer end, the fuel injection pump stops supplying oil, and the work in the cylinder no longer breaks out, but the engine running at high speed after the flying car cannot stop immediately, and will continue to run for a period of time under the action of great inertia. At the same time, the timing gear shaft of the fuel injection pump will continue to rotate through the transmission between the timing gears. In this way, the timing gear will apply an impact torque to the drive shaft of the oil pump to drive it to continue to rotate. Because the rotation of the flyweight end of the camshaft is blocked, the bakelite connecting block of the coupling may be crushed, and the connecting key between the timing gear of the fuel injection pump and the gear shaft may be cut off and misaligned from the original matching position. At the same time, the diameter of the oil pump camshaft processed as a casting is larger than that of the oil pump timing gear shaft as a slender rod. When the flyweight breaks down the governor housing and the oil pump is forcibly stopped, the timing gear shaft will be distorted under the action of the huge impact torque caused by the continuous high-speed rotation of the engine, and the angle of the flange disc end lags behind that of the timing gear end. Therefore, when the governor breaks the shell, if the high-pressure oil pump is simply repaired and calibrated, it will be loaded and started, which often fails. A more thorough treatment is to open the timing gear chamber cover and check whether the oil pump timing gear shaft is keyed. If so, remove the gear shaft and refit the key. If there is no rolling key, check the distortion of the gear shaft. Align the timing mark first, and then turn the engine crankshaft to the required angle of the fuel supply advance angle scribed line of the cylinder 1 on the flywheel. Install the oil pump on the engine body, connect the inlet and return oil pipe, and do not install the high-pressure oil pipe. Do not install the positioning screw of the coupling flange plate. After the oil pump exhausts air and fills with diesel, turn the flange to the starting position of oil supply of cylinder 1. At this time, check the relative position between the positioning screw hole and the arc groove on the front flange plate. If the difference angle is too large to be adjusted by the coupling, then readjust the oil pump timing gear, that is, extract the oil pump gear shaft, rotate the gear shaft in the normal rotation direction in the free state, until the center of the arc hole of the coupling drive flange plate is directly opposite to the middle flange plate fixing screw hole, install the gear shaft according to this position, and tighten the flange plate fixing screw, The fuel supply timing of the fuel injection pump can be restored. At the same time, the timing mark should be re marked on the corresponding teeth according to the number of differential teeth, which is conducive to subsequent maintenance work. Mao Xian graduated from Shijiazhuang railway fatigue college and is currently a mechanical engineer in the second division of the tenth five year Railway Engineering Bureau

if the front-end space of the engine is too small, the timing gear chamber cover can be opened only when the engine is lifted out, and there is no lifting equipment on site, and on-site first aid is required, the following treatment can be carried out: reinstall the calibrated oil pump according to the normal installation position, connect the low-pressure oil circuit, drain the gas and fill the oil. Open the valve cover of cylinder 1, turn the crankshaft and check the movement of the rocker arm of the intake and exhaust valves of cylinder 1 at the same time, until the start of oil supply of cylinder 1 on the flywheel. Turn the driven plate of the coupling to the oil outlet of the tight seat of the oil outlet valve of cylinder 1. The oil level fluctuates and stops rotating. Turn the driven flange plate in the opposite direction until the fixing screw of the middle flange plate is directly opposite to the center of the arc-shaped long hole on the drive flange plate, and fix the fixing screw of the flange plate. Cover the wet mud on the engine body directly opposite to the timing gear shaft, and heat the timing gear shaft with a blowtorch or oxyacetylene flame until the driven flange plate can be pulled at the oil pump end with an open-ended wrench according to the rotation direction of the fuel injection pump. Do not overheat. At this time, the oil pump rotates, and the timing gear end cannot rotate due to the static state of the engine. Until the oil level at the oil outlet of the tight seat of the oil outlet valve of cylinder 1 fluctuates obviously, keep this position until the timing gear shaft is cooled. In this way, the fuel injection pump and the timing gear shaft return to the corresponding position before the shaft is distorted. Continue to turn the crankshaft for a week, and the side on the timing gear shaft that the flame did not directly heat up during the first heating turns to the outside. Second, what is more serious is that if these dust enters the hydraulic system of the electro-hydraulic servo universal testing machine for the second heating, it is basically the same as the first heating. After cooling, the residual internal stress of the two corresponding surfaces on the axle is basically the same. The shaft will not have obvious deflection and deformation, and the transmission stability is good. The above method is relatively simple and can be used for on-site emergency. However, because the heating temperature is not easy to control, the gear shaft inevitably has deflection deformation caused by the uneven residual stress and the joint development of innovative, environmental friendly and sustainable adhesive technology and new utilization balance. When conditions permit, the best effect is to replace the timing gear shaft

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