Diesel generator maintenance training diesel article -p29-p31 crankshaft and flywheel

The power output of the diesel generator diesel engine is all achieved through the crankshaft. For this purpose, the crankshaft assists the piston connecting rod assembly to greatly change the force, pressure, tension and bending force.

(1) Crankshaft-prone fault Diesel engine journal wear during abnormal use and long-term use.

(2) Main Causes of Crankshaft Failure

1 The main causes of crankshaft cracking: First, the bearing, bearing clearance is too large or alloy off, resulting in excessive impact force; Second, the diesel engine is often overloaded; Third, in the light grinding crankshaft, journal to crank arm transition The rounded corners are too small: Fourth, the crankshaft is used for too long, causing fatigue damage. Cracks easily appear at the crank arm, as shown in Figure 2.29.

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7 The main reasons for crankshaft bending: First, the diesel engine is often overloaded with s. Second, the main bearing clearance is too large or the bearings are not uniformly worn; third, the combined crankshaft assembly is not correct. The fourth is the diesel engine top cylinder accident.

2 The main reasons for crankshaft journal wear: First, the individual oil channels inside the crankshaft are blocked instantaneously or the oil pressure is too low: Second, the oil is not replaced for a long time, and there are many internal impurities in the oil. Third, the diesel engine is overloaded.

(3) Inspection and Repair Methods of Diesel Generator Crankshaft Faults

1 crankshaft crack repair methods: The following two methods can be used to check the crack of the crankshaft: First, use the magnetic inspection equipment to check; Second, the crankshaft soaked in diesel for some time, then remove the crankshaft and brown net, in the suspected part of the crack Remove the white powder and hit it with a wooden hammer. If diesel oil is found on the white powder during percussion, cracks will appear. When a crack occurs in the toggle, the crankshaft can be directly replaced for the crankshaft with a modular structure. After the crankshaft has been replaced, it is necessary to conduct a balance check.

2Crankshaft bending overhaul method: place the crankshaft of disassembly F on the horizontal plate, support the two ends of the crankshaft at equal distances, use the contact of the dial indicator to measure a main bearing in the middle of the crankshaft, then use it to turn the crankshaft in a circle. Half of the maximum reading of the hour dial indicator is the curvature of the crankshaft. The bending degree must not exceed o.05mm, and should be corrected if this value is exceeded. When the bending exceeds the maximum standard specified by the technology, it can be corrected by decomposing the crankshaft, scraping the crankshaft end face, adjusting the torque of the through bolt, or directly replacing part of the crankshaft.

2 crankshaft wear and repair methods: on the one hand from the outside to check the line, pull the hair, corrosion spots, etc.; on the other hand can be used outside diameter micrometer to measure the main shaft and connecting rod journal outside diameter. If the wear exceeds the maximum specification of the specification, parts of the crankshaft may be replaced.

2. Diesel generator flywheel

The flywheel is made of cast iron and mounted on the rear end of the crankshaft of the diesel engine. Its appearance is shown in Fig. 2.30. The flywheel is a type of kinetic energy storage that can stabilize the speed by adjusting the crankshaft speed change. Multi-effect diesel flywheels are equipped with gear rings and scales. The ring gear is installed for the starter to start the diesel engine. The scale on the flywheel and the pointer on the periphery of the diesel engine body are designed to determine and adjust the diesel fuel advance angle.

(1) Restrictions imposed by the flywheel

In the long-term use of the flywheel, the teeth on the ring gear are easily damaged or severely worn. The reason is that during the numerous starting processes of the diesel engine, the starter pinion and the flywheel tooth pattern often collide or the meshing is not in place. Causes wear and damage to the ring gear.

(2) Inspection method

When the diesel engine is started, if the starter gear and the flywheel ring gear cannot mesh and there is a crash sound, first determine whether the distance between the starter pinion gear and the flywheel ring gear is appropriate. When it is impossible to judge the distance, a flat screwdriver can be used to adjust the adjustment screw under the electromagnetic switch of the starter, as shown in Figure 2-31. If the fault cannot be removed after adjustment, check whether the battery voltage and capacity meet the start-up requirements. When both of them are in compliance with the technical requirements and the diesel engine still cannot be started, use a screwdriver to rotate the flywheel to check if the flywheel tooth group is damaged.

(3) Repair methods

Under normal circumstances, you can continue to use the flywheel gear ring overturned. When more than three teeth are damaged or both sides of the ring gear are seriously worn, it can be repaired or replaced with a new type of the same model.

The gas distribution mechanism, the intake and exhaust system, and the gas distribution mechanism are the control mechanisms for the intake and exhaust of diesel engines. It controls the opening and closing of the intake and exhaust valves according to the working order of each cylinder of the diesel engine to ensure that enough fresh air enters the cylinder within a specified time. • The well exhausts the burned exhaust gas from the cylinder as thoroughly as possible. Pai mountain.

The lubrication conditions of the moving parts of the valve train are very poor, which can easily cause parts to wear during use. When the wear is exacerbated, the working conditions of the gas distribution mechanism are changed, resulting in a decrease in the power of the diesel engine, an increase in fuel consumption, and other malfunctions. The purpose of repairing the gas distribution mechanism is to restore the original mechanical properties of the parts of the gas distribution mechanism, ensure that the valve is opened and closed on time, and the operation is smooth and noiseless. The diesel generator diesel engine has high power output and low fuel consumption.