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Summer refrigerating products continuously sell like hot cakes! Compressors are widely used in air conditioners, refrigerators, became the most popular summer product, so how to explain the compressor? The working principle of the compressor? Li da refrigeration web editor sums up for you:
One, the noun explanation - compressor
Compressor is the heart of the refrigeration system, it is from the suction suction low temperature low pressure refrigerant gas, through the motor run a piston to be compressed, exhaust pipes to the high temperature and high pressure gas refrigerants, provide power for refrigeration cycle, so as to realize compression and condensation - inflation - evaporation refrigeration cycle (heat). Generally speaking, shell, motor, cylinder, piston compressor, the control equipment (starter and thermal protector) and cooling system. Cooling way has two kinds of oil cooling and natural cooling.
Life general household refrigerator and air conditioner compressor is single phase alternating current (ac) as a power source, the structure and principles of them are basically the same. Both use the refrigerant is different.
Second, the classification of the compressor
Household refrigerator and air conditioner compressor are positive displacement, which can be divided into reciprocating and rotating. Reciprocating compressor using the piston, the crank and connecting rod mechanism or the piston and crank, smooth tube, rotary are using the axis of the crankshaft.
According to the application range and can be divided into low back pressure type, in the back pressure type, high back pressure type. Low back pressure type (evaporation temperature - 35 ~ 15 ?), commonly used in domestic refrigerators, food cooler, etc. In the back pressure type (evaporation temperature - 20 ~ 0 ?), commonly used in soda fountain, milk cooler, etc. High back pressure type (evaporation temperature - 5 ~ 15 ?), is generally used in room air conditioner and dehumidifier, heat pump, etc.
Three, compressor common faults and the reasons and solutions
Failure - exhaust temperature is not normal
Exhaust temperature abnormal refers to its higher than design value. From theoretical progresses, the influencing factors of exhaust temperature increase are: inlet temperature, pressure ratio and compression index (for air compression index K = 1.4). Actual situation affects the inspiratory high temperature factors such as: the middle cooling efficiency is low, or cold in scale and affect the heat transfer, to be behind the level of suction is necessarily high temperature, exhaust temperature will be high. In addition, the air valve leakage, the piston ring leak, not only affect the exhaust temperature, and it also causes a interstage pressure change, as long as the pressure ratio is higher than normal will make the exhaust temperature. In addition, water-cooled machine, lack of water or water shortage will enable higher exhaust temperature.
Fault 2 - displacement
Insufficient displacement is one of the most common fault of the compressor, it is mainly caused by the following reasons:
1, inlet filter failure: fouling congestion, reduce displacement; Air suction pipe is too long, pipe diameter is too small, the suction resistance affects the volume increase, to clean the filter regularly.
2, compressor speed reduce reduce displacement: air compressor use undeserved, because of the air compressor exhaust is according to certain altitude, suction temperature and humidity, when use it in more than the standard on the plateau, inspiratory pressure reducing, displacement will reduce.
3, cylinder, piston, piston ring wear, super bad, make relevant clearance increases, increase leakage, affected the displacement. Belongs to the normal wear and tear, should be timely replacement parts, such as piston ring, etc. Belong to the installation is not correct, clearance is improper to stay, should give correct according to the drawing, if no drawings, preferable experience data, for clearance between the piston and cylinder along the circumference of a circle, such as cast iron piston, clearance value is 0.06/100 ~ 0.09/100 of the diameter of the cylinder; For aluminum alloy piston clearance for the gas to diameter of the diameter of the 0.12/100 ~ 0.18/100; Steel piston desirable smaller value of the aluminum alloy piston.
4, stuffing box is lax, produce a flat lower the volume. The first reason is the gland itself made unsatisfactory; Second may be due to the installation, is bad for the piston rod and stuffing box center, develop blemishes, strain cause air leakage; Generally in filling grease in the packing, it can play the role of lubrication, sealing and cooling.
5, the compressor suction, exhaust valve fault influence on displacement. Between valve seat and valve disc fell into pieces of metal or other sundry, lead to closed lax, form a gas leak. This not only affect the displacement, but also affect the level between the change of pressure and temperature; This problem may be due to it is a manufacturing quality problems, such as valve piece warp, the second is due to the seat and worn valve plates to form a gas leak.
6, valve spring force of matching with the bad. Stretch too makes the valve open slowly, stretch too weak valve closed timely, which not only affects the volume, but also will affect the increase of the power, and the life of the valve valve, spring. At the same time, will also affect the gas pressure and temperature changes.
7, improper pressure valve of the pressure force. Pressure force is small, flat, too tight or not, of course, can make the valve cover deformation, damage, general compression force calculate under type: p = k PI / 4 D2P2, D the cavity diameter of valve, P2 as the largest gas pressure, k is greater than 1 value, generally take 1.5 ~ 2.5, low k = 1.5 ~ 2.0, high pressure when k = 1.5 ~ 1.5. So take k, proved to be good. Valve has failed, the cover will be fever, at the same time pressure is not normal.
Fault 3 - pressure is not normal and lower exhaust pressure
Compressor exhaust gas under rated pressure can not meet the requirement of the user's flow, the exhaust pressure are bound to reduce. At this time, had to the other in a same exhaust pressure, and large displacement of machines. Affecting the interstage pressure is the main reason of the abnormal air valve leakage or air leakage after piston ring wear, therefore, from these aspects to find the reason and take action.
Four - overheating fault fault
In crankshaft and bearing, cross and skateboarding, packing and the piston rod, friction, temperature in excess of the prescribed value called overheating. About the consequences of overheating: one is to speed up the abrasion between the friction pair, the second is a heat caused by friction heat build-up of straight to burn surface machine of major accidents. The cause of bearing temperature mainly include: uneven bearing and shaft neck joint or contact area is too small; Bearing bending deflection of the crankshaft, lubricating oil viscosity is too small, oil plug, oil pump failure fault oil etc; When installation, no leveling, no find good clearance, spindle and motor shaft without alignment, there are two axis tilted, etc.
Five - the abnormal noise fault
Compressor failure occurs if some parts, will send out the abnormal noise, generally speaking, the operator can identify abnormal sound. The piston and cylinder head clearance is too small, a direct hit; The piston rod and the piston connecting nut loose or tripping; The piston end plug juniper, piston upward string dynamic collision cylinder cover; Fall into the metal debris in cylinder and the accumulation of water in cylinder can be dispersed in the cylinder is knocking. Crankcase in bolt, nut, crankshaft connecting rod, crosshead bolt looseness, tripping, and broken, trunnion badly worn clearance increases, cross pin and bushing fit clearance is too large, or wear and so on, are available on the voice in the crankcase. Exhaust valve broken, valve spring, loose or damage to the load controller tuning was improper and so on can be dispersed in the valve chamber tapping. To find fault and take measures.
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