Ten methods for fault diagnosis of the hottest ins

2022-07-24
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Ten methods for instrument and meter fault diagnosis

the reason is that the output pressure and flow of the main pump are insufficient or the clearance of the internal mating parts of the hydraulic motor increases

inspection and troubleshooting methods:

(1) on the premise that the main circuit safety valve, overload valve and other accessories are intact, seal the interface between the oil inlet pipe and the motor (no oil leakage), and measure the maximum pressure of the oil supply circuit when the motor is in forward and reverse rotation; Then connect the motor pipeline and measure the pressure under load; Finally, the fault position can be determined by comparing the measured value with its technical requirements

(2) because the insufficient flow or low pressure of the hydraulic pump will reduce the output power of the motor and the torque and speed at the same time, the measured flow should be carried out synchronously with the measured pressure

(3) check whether the clearance between the valve distribution shaft and the rotor hole is within the allowable range (see the attached table), check whether the rotation center line of the valve distribution shaft and the cylinder block hole is consistent, and reassemble if it exceeds the allowable value. If the fit clearance between the valve distribution shaft and the rotor hole exceeds 0.6mm, or the valve distribution hole in the rotor has a groove along the circumference; When the fit clearance between the plunger and the rotor exceeds 0.05mm, and the fit clearance between the roller square shaft and the chute exceeds 0.05mm, the low-speed high torque internal curve motor will be unable to rotate. If the two travel motors are not synchronized, the track will deviate

(4) for the swashplate axial piston motor, after long-term high-speed operation, the bearing clearance of the motor output shaft will increase, and the axial positioning clearance will exceed the compensation value of the large disc spring; Cylinder block (rotor) and valve distribution cross check: the four disc springs on the central positioning rod can not normally press the rotor cylinder to the valve distribution plate (when the fatigue strength of the disc spring decreases, the motor can operate normally in the cold state, and the deformation of the disc spring will increase in the hot state), resulting in the decrease of the valve distribution capacity and the weak operation of the motor. When the clearance between the rotor and the cylinder hole exceeds 0.05mm, or the wear exceeds the normal value, the motor will be weak and run slowly

2. The possible causes of leakage

may be: the valve plate (port) is worn or strained, the plunger hole and plunger are worn, resulting in poor sealing between high and low pressure chambers, and it is difficult to form high pressure in the working chamber, resulting in insufficient oil inlet; The leakage amount is related to the pressure difference between the inlet and outlet of the motor, oil viscosity, displacement, flow distribution structure, processing and assembly quality, etc. the unstable leakage amount will cause the motor speed to be unstable, jittery or stop when turning; The oil return of the oil drain pipeline is not smooth, which promotes the increase of low-pressure oil pressure, resulting in the decline of the sealing effect of the framework oil seal, and makes the oil leak from the motor output shaft end to the reducer housing (or brake); The supporting bearing of motor output shaft is damaged, which will produce eccentric leakage and abnormal noise; Internal leakage will cause the motor locking and braking performance to decline. If it cannot stop at a certain position accurately, the excavator will slip, which is extremely unsafe

inspection and troubleshooting methods: check whether the oil distribution shaft or the inner surface of the cylinder block hole is scratched, clean it first, and replace it if it is serious; If there are roughening and grooves on the mating surface of the plunger and the plunger hole during inspection, the mating surface shall be ground after grinding and polishing, and the serious ones shall be replaced; Check whether the clearance between the plunger and the mating surface of the plunger hole is too large (generally within 8 of the plunger diameter), and replace it if necessary; For the internal leakage of high-speed Magda, the motor oil drain pipe can be disassembled and inspected. New material research institutions and R & D teams at home and abroad such as Tsinghua University, Peking University, Tongji and Fudan University can measure the oil leakage per unit time of the shell respectively during idling and loading to determine the fault degree

3. Creeping

may be caused by unstable leakage, damage to motor support frame, change in bearing positioning, wear of parts, serious oil pollution, and incorrect phase of valve distribution shaft and guide rail surface, resulting in inaccurate oil distribution and inconsistent forward and reverse rotation speeds. Inspection and Troubleshooting: clean or replace the oil distribution shaft or 3 If the cylinder body of the pointer rotating shaft is dirty, if the motor support frame is damaged, the bearing positioning changes or the parts are worn, replace and readjust the bearing positioning; If the oil distribution is inaccurate due to the wrong phase between the valve distribution shaft and the guide rail surface, the no-load test run shall be carried out, loosen the fixed nut on the fine adjustment cam, rotate the fine adjustment cam, adjust the relative position between the valve distribution shaft and the guide rail surface until the phenomenon disappears, and then lock the nut; After calibrating the phase angle of the valve distribution shaft in the test machine, it is generally not allowed to move again at will

4. The rotor is stuck

the reason may be that the clearance between the plunger and the plunger hole, the rotor hole and the valve distribution shaft increases, and the wear debris in the oil enters the motor with the high-pressure oil, blocking the motor; The back pressure oil inlet throttle hole in the heat dissipation circuit is blocked, resulting in poor heat dissipation, which can not wash away the internal pollutants of the motor, raising the local temperature of the precise mating parts such as the valve distribution pair and the plunger pair, and causing the electromechanical device to be stuck by driving the screw rod to change the thermal shock through the reducer and other 1-series transmission head mechanisms; Each strip mark of the high-speed column indicates the position of fatigue crack at the end of each cycle. Wear debris of the valve plate of the plug motor and impurities in the system enter the column plug hole, causing cylinder pulling, cylinder biting and jamming; The loose screw of the return disk causes the deformation of the return disk, makes the spherical surface of the plunger inflexible, and causes the plunger and the return disk to be stuck

inspection and troubleshooting methods: disassemble the hydraulic motor, clean the parts, and replace the damaged parts; If the matching clearance between the valve pair and the plunger pair is incorrect, it should also be replaced; Replace the fluid if necessary

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