1. The relationship between abnormal noise and engine speed
The existence of the most common abnormal noises in engines depends on the condition of the engine speed.
1. Abnormal noise only exists at idle or low speeds. The reasons for the noise include: too much clearance between the piston and the cylinder wall; too tight mounting of the piston pin or too tight mounting of the connecting rod bearing too much clearance between the pusher and its valve guide hole; cam profile; sometimes the starter latch is loose and the pulley is damaged (squealing visible when changing speeds).
2. The sound is chaotic when maintaining a certain speed, and short-term sounds occur one after another during rapid deceleration. The reasons for the noise are: the camshaft timing gear is cracked or its fixing nut is loose; the crankshaft is broken; the piston pin bushing is loose ; The camshaft axial play is too large or its bushing is loose.
3. Abnormal noise occurs when the engine accelerates quickly, and the sound still exists when the engine runs at high speed. The reasons for the noise are: the connecting rod bearing is loose, the bushing is burned, or the size does not match and rotates; the crankshaft bearing is loose or the bushing is burned; broken.
2. The relationship between abnormal noise and load
Many abnormal noises on the motor are obviously linked to their load. During diagnosis, the method of unloading cylinders one by one can be changed. used for testing. Usually, the single or double cylinder ignition method relieves the load on one or two cylinders to identify the relationship between abnormal noise and load.
1. The fire in a certain cylinder is cut off and the abnormal noise disappears or is reduced. The reasons for this noise are: knockingu piston on cylinder; loose connecting rod bearing; leaking broken piston pin;
2. If the fire in a certain cylinder is cut off, the sound will increase or there will be no sound at that time. The reasons for the noise are: the copper sleeve of the piston pin is loose; the conicity of the piston skirt is too great; the connecting rod bearing cover mounting bolts are too loose; or the connecting rod bearing is too loose; the alloy melted; The steering wheel mounting bolts are too loose.
3. The abnormal noise of two adjacent cylinders cutting the fire is reduced or disappears. The reasons for the noise are: a loose crankshaft bearing.
3. The relationship between abnormal sound and temperature
1. It makes noise at low temperature, when the temperature increases, the sound decreases or even disappears. The reasons for the noise are: the gap between the piston and the cylinder wall is too large; the piston is not aligned due to the depth and width of the main bearing oil groove; engine oil pressure is low and lubrication is poor; .
2. There is a sound when the temperature increases, and the sound decreases or disappears when the temperature drops. Reasons for noise include: premature ignition caused by overheating; the long and short axes of the piston skirt ellipse are in opposite directions; the ovality of the piston is small and the gap between the piston and the cylinder wall is too small; is distorted; the gaps between the piston rings are too small.
4. The relationship between abnormal noise and engine duty cycle
Engine abnormal noise failures are often obviously related to the motor duty cycle, especially the crank rod mechanism and the crank mechanism. valve. the noises are all related to the work cycle. For a motor withfour-stroke, any noise caused by the crank rod mechanism is emitted twice once when the engine is running; all sounds caused by the valve mechanism are emitted once when the engine is running;
1. The causes of abnormal noise caused by the crank-connecting rod mechanism are: the piston knocks against the cylinder wall; knocking noise coming from the piston pin; is too loose; Piston rings are leaking.
2. Causes of abnormal noise caused by the valve mechanism include: excessive valve clearance; excessive clearance between the lifter and its guide hole; broken valve spring; radially cracked camshaft timing gear; Valve seat ring loose and unable to close.
3. If the abnormal sound has nothing to do with the duty cycle, you need to pay attention to the area where it makes the sound. Usually the noise caused by the gap which has nothing to do withduty cycle is mainly a fault in engine accessories; If there is a continuous metallic friction noise coming from the machine parts that has nothing to do with the work cycle, this may indicate that some rotating parts are defective.
5. The relationship between abnormal noise and engine parts
When the engine emits abnormal noise, it will inevitably produce a certain degree of vibration depending on the characteristics and location of the vibration. , it can help diagnose the cause of abnormal noise.
1. Characteristics of abnormal noise from connecting rod bearing: When the engine accelerates suddenly, there is a continuous and obvious knocking noise of "block, block, block". The bearing and connecting rod journal are too tight and the radial adjustment clearance is too large. The alloy layer of the connecting rod bearing is burned or peeled off. Bonnet mounting boltsconnecting rod bearings are loose or broken. Oil pressure is too low or oil is too thin. The engine operates for a long time at high temperature and heavy load.
2. Diagnosis and troubleshooting methods for abnormal noise in generator bearings:
First check whether the fan V-belt is shaking. If it operates normally, pay attention to the sound it makes. by the generator. If the sound is high and harsh, it means the brush is beating on the slip ring (you will see blue at night) if the sound is high and sharp, it means the bearing is loose or the ring is damaged; is heavy, this means that the rotor and stator collide.
The abnormal generator bearing noise is a soft, continuous “rusting” sound. As the engine speed increases, the tone of the abnormal noise becomes higher pitched. The reason for the abnormal noise of the generator bearings is that the generator has not pwas serviced on time and grease was added to the bearings, causing bearing wear due to lack of lubrication.
Abnormal noise from bearings of Shanyu generators is usually slight and is often mixed with engine operating noise, making diagnosis difficult. To determine whether the abnormal noise is caused by the generator bearing, you can remove the generator belt after stopping the engine, adjust its tension to completely loosen it, and then run the engine. If the abnormal noise disappears at that time, it. means the original abnormal noise was caused by the generator bearing race.
When the generator bearings make abnormal noise, the generator should be disassembled and disassembled, and the damaged bearings should be replaced. The bearing noise is relatively fragile, which can be determined by removing the belt. Remove the bearings and veecheck the degree of wear, and add an appropriate amount of grease if the rotor and stator collide, repair or replace the parts according to the surface marks, correct the curvature of the generator shaft, replace the brushes coal with new ones, and assemble the belt pulley correctly to avoid collision with the generator heat sink.
The generator makes abnormal noises when operating, which is usually a mechanical failure. The reasons are: the fan belt is too loose or too tight; the generator bearing is damaged, stuck or poorly lubricated; the rotor and stator collide (commonly called “sweep”); the ring is wrong, causing the carbon brush to tip into the frame. The swing makes noise; the generator is not in place when reinstalled and the body tilts, causing the generator motor armature shaft to be benté and the pulley rubs against the generator heat sink.
Detailed informationGenerator operating procedures:
1. Before starting, check whether there is sufficient oil in the fuel tank and whether there are oil leaks in each oil pipe and joint. Whether the water in the cooling system is sufficient, clean and leak-free, and whether the fan belt is properly tightened. Check that the transmission parts of the internal combustion engine and generator should be reliably connected, the output line wires should be well insulated, and all instruments should be complete and efficient.
2. After starting, it should run at low speed for 3-5 minutes. The operation can only be started after the oil temperature and pressure are normal. There should be no abnormal noise when the generator accelerates, the slip ring and the brushesis of the collector must be in good contact and there must be no jump or spark. After the operation is stable and the frequency and voltage reach the rated values, power can be supplied externally.
3. When abnormal noise, odor, sharp increase in water temperature, sharp drop in oil pressure, etc. occur. occur during operation, the machine should be stopped immediately for inspection and troubleshooting.
4. The generator power factor should not exceed late phase (lag) 0.95. The variation range of the frequency value should not exceed 0.5 Hz.
5. Before stopping, you must first turn off the main switches of each power branch, gradually reduce the load, then turn off the main power switch of the generator and return the excitation rheostat to the maximum resistance position to reduce the tension to the minimum value, then turn off the excitation switch and the neutral point grounding switch, and finally stop the operation of the internal combustion engine. ?
Data source: Baidu Encyclopedia: Generator Operation Procedures