Thursday, October 15, 2020

What Are The Common Faults Of Automatic Ac Compressors?

What Are The Common Faults Of Automatic Ac Compressors?

Insufficient exhaust

Insufficient displacement is one of the most prone to failures of the Auto ac compressor, and its occurrence is mainly caused by the following reasons:

1. Malfunction of the oil inlet filter: blocking the fouling and reducing the exhaust volume; the suction pipe is too long and the pipe diameter is too small, which increases the suction resistance and affects the gas volume. The filter should be cleaned regularly.

2. The reduced compressor speed will reduce the displacement: improper use of the air compressor, because the displacement of the air compressor is designed according to a certain altitude, compressor suction temperature and humidity. When starting, the suction pressure decreases and the displacement inevitably decreases.

3. The cylinder, piston and piston ring are severely worn and out of tolerance, which will increase the relevant clearance and increase leakage, thereby affecting the displacement. If it is normal wear, the wearing parts, such as piston rings, must be replaced in time. If the installation is incorrect and the clearance is inappropriate, it should be corrected according to the drawings. If there are no drawings, empirical data can be obtained. For the circumferential gap between the piston and the cylinder (such as a cast iron piston), the gap value is the cylinder diameter. 0.06/100~0.09/100; For aluminum alloy pistons, the clearance is 0.12/100~0.18/100 of the gas path diameter; steel pistons can use the smaller value of aluminum alloy pistons.

4. The stuffing box is not strict and will leak to reduce the amount of gas. The reason is that there is no need to fill the box itself in the first place. The second reason may be the misalignment of the piston rod and stuffing box during the installation process, resulting in air leakage due to wear and strain. Usually, the stuffing is filled in the stuffing box. It can play the role of lubrication, sealing and cooling.

The exhaust temperature is abnormal

Abnormal exhaust temperature means that the temperature is higher than the design value. Theoretically, the factors that affect the increase in exhaust temperature are: intake temperature, pressure ratio and compression index (for air compression index K = 1.4). The actual situation will affect the factors of high suction temperature, such as: low intercooling efficiency, or the scale connection in the intercooler will affect heat exchange, the later suction temperature must be higher, and the exhaust temperature will be higher. In addition, valve leakage and piston ring leakage, which not only affect the increase of exhaust temperature, but also change the pressure between stages. As long as the pressure ratio is higher than the normal value, the exhaust temperature will rise. In addition, water-cooled machines that lack or lack water will increase the exhaust temperature.

Pressure is not normal

If the volume of gas discharged from the car compressor does not meet the flow requirements of the user at the rated pressure, the exhaust pressure must be reduced. At this point, I had to change another machine with the same exhaust pressure and a large exhaust volume. The main reason for the abnormal pressure between the stages is the leakage of the gas valve or the leakage of the piston ring. Therefore, the reasons and measures should be taken from these aspects.

Abnormal sound

If some parts of the automotive ac compressor fail, an abnormal sound will be emitted. Generally speaking, the operator can discern the abnormal sound. The gap between the piston and the cylinder head is too small and directly impacts; the piston rod and the piston connecting nut are loose or tripped; the piston end face is blocked, the piston moves up against the cylinder head; the metal fragments in the cylinder and the water accumulated in the cylinder Both can make a knocking sound in the cylinder. Crankshaft bolts, nuts, connecting rod bolts, crosshead bolt loosening, tripping, breaking, etc. in the crankcase, the shaft diameter is seriously worn, the clearance is increased, the clearance between the crosshead pin and the bushing is too large or the wear is serious, etc. A percussion sound is heard in the crankcase. The venting valve piece is broken, the valve spring is soft or damaged, and the load regulator is improperly adjusted, etc., and the knocking sound can be emitted in the valve cavity. This is to find faults and take measures.

Overheating failure

In the friction between the crankshaft and the bearing, the crosshead and the slider, the packing and the piston rod, the temperature exceeds the specified value, which is called overheating. The consequences of overheating: one is to accelerate the wear of the friction pair, and the other is to accumulate and burn the friction surface due to excessive heat and cause a major accident. The main reasons for bearing overheating are: uneven bearing or journal contact or too small contact area; bearing deflection, crankshaft bending, lubricating oil viscosity too small, oil circuit blockage, oil pump failure, oil cut, etc.; no gap, spindle and motor shaft Misaligned, and both axes are tilted.

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