Air Conditioner Compressor is the host, like the heart of people. Air-conditioner performance, reliability, as well as more than 10 years of operational life must be to ensure the compressor. How to improve as a host - the reliability of the compressor, refrigeration industry has been a concern, the following over the years on the basis of its own rotary compressor to engage in technical practice and in recent years, the well-known brands abroad rotary compressor of analysis is as follows views.

1. Rotary compressor is a high-precision, small-scale power machinery. Movement within high and low pressure channel gap entirely, sealing film, the sliding friction between the gap is formed on the film for lubrication to reduce wear and ensure reliability, long life.

1.1 to keep sliding movement between the uniform and small pieces of the gap is to improve the compressor performance and reliability of the precondition.
1.1.1 Cylinder Vane vane slot and the gap.

    Product plans provide that the gap between the two compressors for the 20 ~ 30μm, small high-speed inverter compressor can be reduced to 15 ~ 20μm. Process requires sliding the way to free-falling through the sliding slot, to prove that the gap between the two evenly. The purpose of the realization: not only guide vane vane slot free movement and scrolling up and down piston, cylinder wall cavity with the composition of exhaust smoke and a seal, but also the formation of high-pressure oil film, and ensure lubrication, reducing wear to improve reliability, to create conditions. However, the traditional manufacturing process is a three-point welding method to connect the cylinder and the shell. Three-spot of thermal stress leading to the formation of the cylinder housing contraction sliding of the extrusion slot, so that the deformation resulting sliding slot. This will not only affect the gap between the two with the uniform, and even may be stuck fault sliding. Analysis of deformation of the impact of factors: with the cylinder structure, material, three spot welding conditions, and movement with the way the connection housing. Ax traditional cylinder-shaped (Figure 1) after the welding deformation of the greatest, especially when low-strength material (such as the use of metal castings eutectic), the three-spot parameters properly, the three parameters of heterogeneity, the time is not synchronized, its deformation can be as high as or even more than 15μm. I have seen a factory spot after three 1 / 3 or more dead compressor vane Soyinka and offline. First of all the pressure on the structure and material cylinder to improve the Japanese "Mitsubishi Electric." They spoke through the use of cylinder-type (Figure 2) FC25 sand castings, will be deformation of sliding control slot within 5μm. In order to ensure uniformity of both space and reduce the gap for the appropriate value to provide a prerequisite. The early 80s, Mitsubishi Electric refrigerator in the rotary compressor will be replaced by welding the welding cylinder bearings (rack) and the bearing-shaped spokes designed to reduce the impact of heat stress (Figure 3). In order to avoid the deformation of the sliding slot. At present, the major compressor manufacturers in Japan to develop new products, basically the use of spoke-type cylinder with the welding process on the bearings. On the basis of Mitsubishi Electric, Matsushita Electric will also be traditional sliding Broaching slot milling + grinding process changed the method, thus the size of sliding slot accuracy of ± 1μm, on both sides of the parallel surface, the flatness from 7μm to 4μm, so that the vane and vane slot with the gap narrowing to less than 15 ~ 20μm, in order to improve efficiency, reduce wear and avoid the death card, created the conditions to ensure reliability. (See Figure 1,2,3)


1.1.2 appropriate to reduce the (main) and the crankshaft bearing clearance, the appropriate increase in height of the main bearing is a rotary compressor to ensure stability and reduce vibration and noise, the effective measures to improve reliability. At present, there are already some of the gap between the two companies will be reduced to about 20μm, new and improved Panasonic 2K series, the main bearings has been increased to a high degree of 52μm, South Korea LG III in the process from the welding spot welding cylinder replaced the main bearings At the same time, the main bearing will also be high from 47.5mm to 54.7mm, have brought the functioning of stability, to reduce the effects of wear. In order to achieve not only narrow the gap to increase the gap can also enable a high degree of uniformity of purpose, in addition to technology to improve the long axis of the crankshaft machining accuracy, but also on the main bearing hole to take in a round honing after grinding process. In order to avoid the crankshaft and main bearing hole to mention too high machining accuracy can be taken on the two matching methods.

1.1.3 With the rotary compressor manufacturing process improvements and equipment level, with the other space (such as cylinder and piston (high), and sliding the cylinder (H), piston and crankshaft with eccentric circular hole ... ... and so on) have further narrowing trend. This will improve the performance of the compressor to ensure the same reliability as well. )

1.2 to take a strong supply system, to the movement of the sliding parts of the provision of adequate and has some of the lubricating oil pressure is to ensure sealing to enhance performance, ensure the lubrication and reduce wear and improve the reliability of an important means.

1.2.1 pumping compressor blade design is the key, twist angle should be the size of choice. Too small to lift enough to upgrade; too, will lead to the oil hole in the crankshaft rotation, is not conducive to the formation of a hydraulic high.

1.2.2 Crankshaft hole should be designed as a ladder-shaped leaves with the Department and may be larger, pass the top of the site should be as small as possible number of (LG to 4mm), this design process will help to exclude chips, dirt and more major oil-vane pump in the operation of the process is conducive to the formation of the higher hydraulic hole to raise oil capacity. Sanyo insert in the hole to support the long-selling disc rotor. As the pin insertion hole further narrowed the gap to high oil pressure can be formed, and in favor of oil and gas separation, reduced efflux to the compressor oil, oil tanks to ensure the stability of oil, but also to achieve the purpose of the process is simple, after all, a good structural design.

    Although the crankshaft hole barrier in favor of the formation of higher oil, but if the chip, not have to clean dirt, oil and gas separation is not complete, which in turn will also affect the reliability of the compressor.

1.2.3 In order to ensure adequate supply bearings up and down and evenly distributed throughout the bearing should be in the upper and lower bearings take the initiative to open holes for the tank wall (usually on the bearings for the left, under the bearing for the right).

1.2.4 In order to reduce the emission fuel, some manufacturers also uses L-shaped exhaust pipe.

1.3 Selection of high-quality frozen oil, improve the effectiveness of lubrication sealed to ensure that the safety performance of the compressor.
The function of oil is frozen: the lubrication to minimize friction between parts; maintaining a high level, low pressure area; through high-pressure heat to the outside shell. It should have frozen oil viscosity suitable movement for the formation of oil film in the friction surface, also called frozen oil with high thermal stability, temperature changes in a larger machine, the oil viscosity is still relatively small changes in order to ensure movement has always been to maintain a good part of the sealing and lubrication.

    Seen from Table 1, Nippon Oil (formerly Mitsubishi Oil) specifically developed for Mitsubishi Electric air-conditioning refrigeration compressor oil, MS56, the best performance - the most color-ching, 40 ℃ and 100 ℃ under the conditions of minimal viscosity change, air conditioner compressors, especially in the temperature range of the main work (80 ~ 100 ℃) MS56 maximum viscosity of the campaign - that is, sealing and lubrication performance are the best, at the same time due to its flash point is the highest strength and insulation, so the compression for machine best safety performance is worthy of recommendation Air conditioning industry quality frozen oil.

     Above, to Mitsubishi Electric is a small double inverter compressor as an example: with the introduction of a smaller space, a strong pipeline systems, high-quality frozen oil (MS56), the compressor, as 30Hz, 130 Hr workhorse test, but its ability to increase refrigeration (± 0.35%), energy efficiency (COP) has not only failed to reduce rather than increase (± 1.03%), reached a similar saturation of the desired effect. By the anatomical analysis: their sliding and wear parts are also very small. Cylinder, sliding slot, inhalation side of the largest local wear only 6μm, just out side 9μm, face the greatest R Vane wear only 1.5μm, the length of the crankshaft axis of the local wear less in the 2μm, the largest main bearing wear 2μm also within, it can be said are very small.

2. Control Series range, the appropriate cylinder to raise the height of the crankshaft eccentric reduce the amount of centrifugal compressors is to reduce the load to maintain stability in an effective way to operate. Such as Mitsubishi Electric of Japan to "RH" series of core components, the structure is divided into large and small. Minicomputer small displacement, cylinder thickness as 23.8. Mainframe displacement, and cylinder thickness as 30.8. As a result of large and small, broken down to make the series more smaller minicomputers. Mainframe as a result of the increase in the thickness of the cylinder displacement effect increases accordingly, so that the eccentric crankshaft mainframe relatively reduced, reducing the centrifugal load, reduce vibration, improve the reliability. But there are a number of manufacturers to expand the scope of product support, not appropriate to raise the shaft eccentric moments, centrifugal load increases too much, sacrificing the reliability of the compressor and damage the interests of consumers.

3. Rotary compressor core components in the smoke, the exhaust process, under alternating load, in order to improve the main components of the force. Reduce vibration, and many well-known manufacturers of products used in a flexible support structure to good effect.

3.1 To improve the crankshaft by the power and increase the pressure surface, and supported with a certain degree of flexibility, high-capacity compressor, the flat end of the bearing supporting hole opened nearly a deeper (usually the width of about 1.5mm, the depth of about 8mm) of the trough. (Figure 4) Japan's Mitsubishi Electric "PH, NH" series mainframe species, LG compressor capacity of more than 29cc/rev and double high-level inverter compressor used in this structure, are effective. (See Figure 4)

3.2 in Japan, "Toshiba" will only push the crankshaft eccentric round face from under the surface of the annular head replaced the crankshaft end, and the use of fixed bearings in the Department of Small Cylindrical Thrust Block (flexible), under which the use by Thrust surface of the nitride film support (Figure 5), not only because of the structure of the entire compressor rotor bearing surface and the center of gravity of coincidence, is conducive to the functioning of stability and flexibility to support the functioning of the absorption process of the crankshaft torque change due to the vibration, so as to further enhance the reliability of the compressor. (See Figure 5)

3.3 in Japan, "Toshiba" three spot welding process used in the structure of the transition-specific flange (Figure 6) the way (that is, in the shell on the first connection of a three-spot casting (to process)) or pressing the transition law Lan, by engaging in quasi-relative position processing, the cylinder and then fixed on the flange during the transition. This structure not only to avoid a three-spot on the impact of sliding slot, and the smaller cylinder can also be produced, and in the course of the freedom of assembly to adjust the electrical stator and rotor vapor gap and improve the starting performance of the compressor. Compressor in a large cast iron as the transition process has also played a flange noise absorber use. (See Figure 6)
4, selection of high strength, good wear resistance of materials to make the compressor is to reduce the wear of sliding parts, an important guarantee for the extension of life.

4.1, as a result of sliding movement of the compressor parts were working in the state of lubrication, lubrication should be selected with excellent anti-wear performance of metal materials. Pearlitic gray cast iron, its microstructure is soft on the distribution of the matrix of the components of hard tissue. Such organizations in the running after the matrix has formed a trench to keep wear and tear film, and the graphite matrix tablets at the same time, plays a role in lubrication oil, so the wear-resistance are particularly good, the world's leading manufacturers have adopted the FC25 ( considerable domestic brands HT25-47) to produce pearlitic gray cast iron cylinder compressor with the upper and lower bearings. Also, because the cylinder is the basis of the compressor parts, upper and lower bearing fastening its two coaxiality, cylindrical piston and cylinder wall to form the eccentric gap after adjusting screws are on tight fixed to the prestressing force to ensure that, at the same time slot sliding cylinder and the sliding between the friction there is a great, and called for their materials in addition to having good anti-wear performance and anti-wear ability. Japan's Mitsubishi Electric to add to take P, Cr, Mn, Sn alloying elements. Japan, "Chi said," then add elements V.P. These alloys are also organized to promote the further refinement of the light body to improve the comprehensive mechanical properties of cast iron.

4.2, compressor crankshaft is the most important components of power. In addition to reverse bending force, but also subject to complex alternating stress, so in addition to requirements of the crankshaft has a good mechanical strength, we must also have excellent anti-fatigue properties. Compressor industry is currently the main material used to produce two kinds of Crankshaft: A is "Mitsubishi Electric" and "Toshiba", represented by the use of pearlite nodular cast iron. Another is based on Hitachi, Panasonic, represented by the use of eutectic cast iron mold, the two comparison, as a result of the comprehensive performance is better than a total of ductile iron tether Nippori cast iron, the practice has fully proved this point. So Panasonic, Hitachi is also a newly developed compressor were to switch to ductile iron.

4.3, piston, rotary vane compressor is the most important to pay a pair of friction. Vane and exhaust pressure in the spring, driven by pressure to the piston, R piston outer surface and linear contact friction lead to a drastic operation, easy to wear big. International major compressor manufacturers are looking at how to improve the antiwear ability of sliding. Most of the world's manufacturers to use high-speed tool steel to create slide films, the hardness after heat treatment at about HRC620, mainframe or high-speed variable frequency drive also called for finishing after the gas soft-nitriding treatment, the surface hardness to HV90 ~ 1400.

    Better solution for the sliding wear resistance level, a comprehensive cost factors, the major Japanese manufacturers are trying to. "Mitsubishi Electric" speed machine in the home using Ni, Cr, Mo, B alloys to produce cast iron vane. Wear resistance because it is not only good, but cheap. Frequency in the single-cylinder machines use high-speed steel powder, which formed a good material, and high hardness, porous and oil storage, excellent wear resistance. Small double frequency machine high-speed tool steel is used, large double frequency machine is used high-speed tool steel + gas soft-nitriding of the vane. Toshiba in various types of compressors are using their own unique sliding alloy (JIS-SUS440) after finishing treatment, the gas soft-nitriding surface hardness of more than Hv900, although the materials can meet the mainframe and the double frequency machine requirements, and higher manufacturing costs, but from the assurance of Toshiba quality and reliability from the user on the requirements of a small set of relatively low-speed machines are also used to produce this material sliding. Also in the new higher speed of the variable frequency drive for the sliding of the piston to ensure that the "follow" and "reliability", requiring the use of light weight but has a better wear resistance of sliding. This material has been the success of Japan's Sanyo Electric to develop - that is, for SiC whisker fiber fiber-reinforced aluminum alloy - (FR-AL), the proportion of 2.85 is 40% of cast iron, bending strength 500Mpa, is 1.67 times that of cast iron . And iron and considerable expansion coefficient can fully meet the requirements of thermal deformation Vane, experiments show that: the materials used in high-speed frequency up to 180Hz Compressor (for a new generation of double frequency plane, the frequency range up to 8 ~ 180Hz). Anti-wear performance, "follow nature" there is no problem.

Material on the piston, the current international practice of two kinds: first, the representative of the United States ROTOREX manufacturers, the use of continuous casting with a high stick Mn. Processing advantage is good, but poor wear resistance. Another is "Mitsubishi Electric", "Toshiba", represented by the use of low-alloy sand castings NiCrMo (Japan, Hitachi is currently not yet developed NiCrCu casting rod, casting its performance and NiCrMo equal), the processing piston This material after heat treatment to form a soft matrix with hard-alloy components compounds organizations. In the conditions of lubrication, the wear resistance particularly good. According to reliable information: The United States also began to use ROTOREX sand casting NiCrMo to replace the traditional casting their rods in order to ensure the reliability of products.

5, the electrical power source is a compressor, which for the contents, so with the same movement, but also has a high temperature and high pressure frozen Penfluridol Pleiades and the harsh environment of oil from the compressor to ensure reliability and security of the whole of departure, containing motor technology in the design, material selection, etc. It should be noted the following points:

5.1, the motor starting torque should be designed to be larger, even if it is necessary to sacrifice some efficiency should also be the case. Objectives are: to ensure that under a lower supply voltage can also be a smooth start. "Mitsubishi Electric" to the compressor reliability, one of which is: under the condition of balance, 180V to a smooth start. Because the electricity will not start, which is equivalent to blocking, rapidly rising current, and even up to a dangerous state.

5.2, motor winding insulation materials and levels of selection, is directly related to the safety of the compressor. Rotary compressor motor does not start the event or stall, one hour in the initial winding temperature can be as high as more than 190 ℃. In order to ensure the reliability of the compressor, an increasing number of manufacturers, select the temperature index for the 200 (C level) QXY / QZY to produce double-layer composite stator winding wire. In order to prevent current in the windings under the mutual friction between the coil insulation damage, and increase heat dissipation effect, "Mitsubishi", "Panasonic" in the coil arrangement Impregnation fixed after banding process. "Toshiba" in the wire since the appearance of a melt layer to increase the use of high-temperature baking process, so that adhesion between coil to achieve the same effect Impregnation.

In order to ensure the quality of the coil in the former production of enameled wire must also be embedded around the anti-test, confirmed by high-speed embedded around the coil after the demolition of a pinhole-free, a single high voltage wire no problem for the product before the official.
Motor stator and rotor made after, but also individual components of the stator voltage and insulation test between the hoop, made of aluminum rotor row off test, sure that there is no problem, to enter the assembly and movement combinations.

6, to prevent the mainframe and high-speed inverter compressor produced in high-speed access to the sliding pieces of iron powder, the accelerated wear of sliding parts, and air-conditioning machine of the pipeline system is adversely affected by the oil pool in the bottom of the installation of a magnet. Adsorption as a result of the magnet can fall into the oil pool will not re-iron powder core components are inhaled, and ensure the reliability of the compression.
 
7, techniques to ensure the reliability of the method:
     Process using some special methods to improve the sliding movement of the surface quality of parts. Such as: surface roughness; Geometric accuracy; surface hardness; anti-wear capacity; improve the running results; as well as to further improve lubrication, reduce heat and wear, table processing techniques.

7.1, to improve surface finish, shape and relative position of the process accuracy.
     Of the exhaust valve, sliding, sliding tailgate (or range limit device) after the pressing and finishing, decorative light to drum (roller Light) deal with the process - to be filled with abrasive parts place (some with special shape the grindstone) and the abrasive roll (roll) inside, with components for several hours with the abrasive between the devil, not only can improve the brightness level, but also completely remove the sharp edge, burr (round down), and generated by the processing of the surface tensile stress into compressive stress, thereby improving the surface of the anti-corrosion, anti-wear ability. Have seen a number of domestic compressor plant to military use of vibration technology for optical components surface decoration finishing process to Mao.
     To further enhance the piston outer surface finish, form and position accuracy, Mitsubishi Electric also increased after the cylindrical grinding process Superfinishing. Superfinishing by the cylindrical surface finish up to more than Cylindricity, roundness can be controlled to less than 1.5μm, has greatly improved with the sliding contact surface condition of R will not only help reduce the wear between the two, but also increased sealing effect.
     Inner circle to improve the processing precision of form and position in favor of the formation of small and uniform with the gap, Mitsubishi Electric and Toshiba, respectively, of the upper and lower bearing hole, the Pistons to take in a round hole after grinding honing process. After grinding through the upper and lower bearing hole roundness, Cylindricity up to the 2 ~ 2.5μm precision-shaped, 0.8 ~ 1Rz the finish. Piston hole roundness, Cylindricity up to 1.5 ~ 2μm precision of form and position, 1.5Rz the finish.

7.2, to improve the sliding surface hardness, increased anti-wear performance.
    To increase the hardness of sliding surface, the use of sulfur Hitachi carbonitriding heat treatment technology, the hardness can reach more than HRc620. "Toshiba", "Mitsubishi," the use of steel or SUS440 high-speed tool steel by heat treatment after finishing the surface to further increase the hardness of the process, the gas soft-nitriding surface hardness up to Hv900 ~ 1400. Panasonic has been sliding by artificial ceramics and aluminum alloy processed by the ceramic vane. Mitsubishi Electric inverter in single-cylinder machines use high-speed steel powder Vane, the hardness after heat treatment up to HRc630.
     Pistons (low alloy cast iron) with the formation of a pair of sliding friction to pay the fine, the general control of the hardness after quenching in HRc450 ~ 530 or HRc470 ~ 550 (mainframe). After quenching in order to ensure a stable microstructure, and some companies are still quenching - tempering treatment to increase outside the rationale for low-temperature (cold processing) processes to ensure long-term operation of the piston and the cylinder outer wall, the piston surface and on both ends , under the bearing surface formed between the two ends of the gap constant.
     In order to enhance anti-exhaust valves and wear ability of Kedah, the major compressor manufacturers in Japan are in place after cutting rolling process research to improve the exhaust port Department tightness of the material structure, to improve their play against the increase in surface hardness anti-wear ability, to extend the service life of valves, valve to reduce leakage losses.

7.3, in order to improve the crankcase and the upper and lower bearings of the running-hole effect, to further improve lubrication between the two major companies rotary compressor crankshaft for manganese phosphating salt treatment, in order to further improve the inter-crankshaft and bearing lubrication, "Mitsubishi Electric", "Panasonic" is still dealing with the basis of manganese impregnated layer of MoS2, after curing plays the role of solid lubricant compressor spindle has greatly improved, the situation of the main bearing wear and prolongs the service life.

7.4, in order to effectively remove the efficiency of the compressor piston cylinder close to the burr, such as a sharp edge components, but also will not back yen (angle) is too large and affect the efficiency of the compressor, rotary compressor in the widely used with abrasive nylon brush to the hair process. Piston, the sharp outer edge at both ends of the cylinder wall surface with the sharp edge formed by the nylon brush to the hair can be formed after a small 0.08 ~ 0.1mm rounded to no sharp edges, burrs without affecting the compressor the effect of volumetric efficiency.

8, for the effective protection of motors, the world's leading compressor plant of greater capacity, air-conditioning compressors are Built to switch temperature, the electric current at the same time protect the protectors (the Department of Mitsubishi Electric and Toshiba all in their own compressor Built-protectors are used), in the frequency plane using device Built-temperature protection. Japan the "party" to protect the company's machine has two kinds of installation: First, in a sealed connector pin end terminal, the feelings of the exhaust temperature and current to protect motor, coil banding This is the way in more reliable.

9, compressor reliability evaluation test method:

     New product development and technology have a significant number of products, materials, structural changes in the reliability of the evaluation must be carried out tests, can be put into operation after the passage. In order to ensure product quality, in the production process should also regularly test the reliability of the sample as if the problem should immediately investigate the reasons, can only rule out the factory. The test must be carried out are:

9.1, heavy duty test. In the evaporation temperature (12 ℃), the condensing temperature (68 ℃) were high, the compressor load the heaviest, most powerful motor shaft 2000Hr ~ 40000Hr through the operation of the pilot, assessment compressor sliding wear resistance of components; valve durability sexual; motor in the anti-oxidation of organic materials. Its criteria are as follows: ① refrigeration capacity of less than 10% decline. ② no abnormal wear movement. ③ no abnormal electrical changes in organic materials.

9.2, high-pressure test: that is, the lower evaporation temperature (-12 ~ -15 ℃) the higher the condensing temperature (+62 ℃), through to assessment 2000Hr compressor operation. At this point the compressor pressure ratio as a result of the largest and the smallest refrigerant flow, core temperature increased, the electrical and cooling is not the case, sliding between components due to thermal expansion may lead to interference. The degradation of organic material will produce, in such circumstances the evaluation than under high-pressure compressor in the reliability of (their evaluation criteria with the same heavy load).

9.3, compressors pass, breaking test: the higher the condensing temperature (62 ℃), low temperature evaporation (8 ℃) condition, in the 7.5s off 7.5s intermittent open cases, the operation of 290,000 times ( the life of the entire air-conditioning compressor to stop the opening of 17 million in general) to test vane springs, rubber feet to avoid vibration, valve lift limit, and the durability of electrical products. Post-test criteria: ① compressor can work, can maintain the pressure ratio. ② ability to change in less than -10%.
     Only through the above tests to evaluate the compressor can be considered as belonging to high-reliability products. In order to supply the market and gain the trust of consumers.