【 Weak current College 】 air source heat pump unit compressor fault analysis

Air source heat pump unit because it comes with heat and cold sources, easy installation, etc., in recent years, widespread application; but because of air conditioning load and external environment, work scope volatile, unit in non-standard conditions run longer, in some poor condition, there have been some compressor unit failure. This article in respect of air-source heat pump in the actual operation of the emergence of some compressor failure issues detailed analysis and presents the appropriate improvement measures.
2 symptoms

Air source heat pump unit used in compressor types more to hermetic reciprocating compressor is common, but the entire seal piston compressor failures, mostly occurs at runtime for heating in winter. Through some fault of the fault and the compressor Anatomy, compressor failure generally fall into three categories:

(1) of the compressor suction valve blade cracked

Phenomenon: compressor oil level normal, compressor bearing, crankshaft, connecting rod intact, suction valve blade cracked.

(2) compressor stalling (such failures more)

Phenomenon: the compressor refrigeration oil is black, upper and lower bearings set off or wear, connecting rod and crankshaft fracture, bearing friction surfaces and crankshaft and connecting rods have the friction surface roughening marks, motor rotor wear marks on the suction valve slice intact.

(3) of the compressor motor burnt

Phenomenon: compressor insulation is 0, the compressor bearing, crankshaft, connecting rod intact.

3 causes

Following the above three categories of failure to carry out a detailed analysis of:

(1) of the compressor suction valve rupture

As can be seen from the symptom, resulting in rupture of the compressor suction valve mainly unit water side system break down, the water into one compressor, forming liquid blow lead valve plate broke.

Water-side system rupture mainly two scenario:

① Whenrun in the refrigeration unit, a river of water, because some users without the flow switch short, units cannot be protected action, water heat exchanger (especially full-hydraulic-type heat exchanger) internal water ice and heat that copper coils, mixed water fluoride, water enters the compressor damage formation fluid hammer.

② in winter, when the user does not use the unit, in accordance with the specifications, the water heat exchanger within the frozen water let or not to freeze measures water heat exchanger internal water ice and heat that copper coils, mixed water fluorine, etc when powering on the unit again, causing water into one compressor. yixun bad

(2) compressor stalling

From such failure phenomena of the anatomy of a compressor, the compressor's internal do not lack of oil, axle stalling due to transient poor lubrication, causing poor lubrication is due mainly to changes in lubrication oil: oil is diluted or the oil level is refrigerant liquid elevation.

A unit back to liquid reasons are:

① in the refrigerant in the refrigeration cycle, usually stored in temperature to the lowest part of the condensate. When the machine head time outage due to the compressor heat capacity than condenser, evaporator, reservoir fluids used in heat capacity, compressor as the minimum temperature in the refrigeration cycle, the refrigerant. As a refrigerant lubricant can be very good solubility, accumulated in the compressor is solubility in the refrigerant in the lubricant, the phenomenon known as "stripping" phenomenon. Refrigerants "into" content depending on the amount of refrigerant charge, refrigeration cycle structure and length of downtime varies, in saturated, roughly the amount of lubricant filling-in 30-100%. Diluted oil will cause poor lubrication, resulting in the axle.

Furthermore, if the machine stop grasping, head of the time, the oil will depend on the temperature of the compressor closed shell, refrigerant and oil types of different liquid separation occurs, divided into lower as refrigerant liquid (refrigerant, refrigerant and oil mixture little), upper for lubricants (oil, lubricants and refrigerants mixture little) this situation. If in such a State that is started for the compressor to the bearings and other movement components of oil are almost only refrigerant fluid "lubricant", therefore, started after a short period of time, bearing section, connecting rod and will produce card dead and wear.

Compressor does not start before the preheated or warm-up time is insufficient, the crankcase heater power not enough time, will not be able to avoid these situations occur, resulting in damage to the compressor.

② When run in the heating unit, particularly in the larger environment humidity operating, fin-easy add cream, if you defrost is not too perfect, can not be timely defrosting or defrost is not complete, will result in low-voltage low, the compressor caused massive back to liquid, the compressor failure.

(3) motor burnt

As noted above, back to the fluid is embrace axis of the main factors that caused by axle bearing eccentric, causing the motor wear, causing the motor short Burnout phenomenon is real. But for purely motor burned down to whether influential fluids? author believes that the hermetic reciprocating compressor, tube-shaped structure determines its liquid hammer is not sensitive, even if some of the liquid refrigerant into one compressor, generally does not directly cause the valve plate broke, it does not directly result in motor burned.

At the same time, because the whole sealing compressor lubrication most flying with centrifugal, no pressure difference control, so the lack of oil-lubricated compressor can run. At this point, the compressor current rise, until air switch (over-current protector) jump off this process of compressor overload, current is large, motor coil temperature rise have quickly until embedded PTC action. Because the rate of temperature rise of PTC compressor in the full-load or overload condition is very sensitive, and air switch is in the PTC before action, the lack of oil as a direct result of a lack of motor burned by it.

Compressor pure motor burned two because of:

① motor temperature rise too high.

Because the whole sealing compressor motorsIs passed back to the gas to cool, winter thermal heat pump mechanism, working poor, especially compared to the ambient temperature is low, the heat exchanger is minimal, the amount of refrigerant cycle back to the small, low air pressure, coupled with the electronic control on defrost not timely and thorough, and will cause the motor to cool enough, coil heating. Such sustained fever will form a high temperature, and PTC on low load of low current reaction is not sensitive, so start with several compressor, have not reached the higher temperatures is due to overheats insulation damage, the electrical short-circuit burnout.

② refrigeration system is not clean, and contain impurities, impurities corrosion and abrasion motor coils, causing a short circuit burnout.

4 improvement measures

The reason for the above analysis, to make the appropriate improvements:

(1) control on frost control features (i.e. down status, when the ambient temperature is below a certain value, the pump or electrical heating should vote people run to waterproof system freezing), at the same time, the water drainage system should be set on the device, when the machine head time when not in use, you should empty the water in a water exchanger to prevent freezing.

(2) in order to guarantee the normal operation of the unit, flow switch and various protection switch cannot be shorted privately; unit at run time, to observe, often found unit in and out of the water temperature is too large, a timely check on water system: water pump is functioning, water and cleaning water filter.

(3) in thecontrol program to increase the pre-boot guarantee crankcase heater heating compression time conditions, ensure the compressor can fully preheating to prevent damage.

(4) improve the defrost, ensure timely defrosting and defrosting is thorough, improving the reliability of control to prevent incorrect operation or action.

(5) improvement of system design, especially in low-temperature heating conditions, should be reasonable for expansion valves and gas-liquid separator match, or to take additional measures such as high-voltage bypass, to prevent the unit back to the solution of problems.

(6) to improve technology, improve management and enhance the sense of quality to ensure that the refrigeration system internal clean cleaning without water, manufacturing process quality is an important factor in generating quality, many issues must take precautionary measures to avoid major problems.

(7) to enhance user's use, operation and maintenance training.