JPS6118026B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a compressor, and in particular to a swash plate type compressor that has recently become widely used for car coolers.The main purpose of the present invention is to provide a compressor with higher performance and a longer lifespan than conventional compressors of this type. It's about doing. As shown in FIG. 1, the swash plate type compressor generally includes a piston 3 moored to a swash plate 5 in a state spanning the swash plate 5, and the piston 3 moves as the swash plate 5 rotates.
The reciprocating motion of the compressor draws in and compresses a medium to be compressed, such as refrigerant gas. The swash plate 5 is rotatably supported by a shaft 4 by a cylinder block 1.
The piston 3 is moored to the swash plate 5 via a shoe 6 and a ball 7. When the shaft 4 and the swash plate 5 are rotated together, the swash plate 5
While sliding on the sliding surface of the swash plate 5, the movement of the outer peripheral portion of the swash plate 5 in the axial direction is transmitted to the piston 3 via the balls 7. In this basic structure, the medium to be compressed, such as refrigerant gas, which has circulated within the refrigeration circuit and returned to the compressor, is compressed to high pressure within the cylinder bore 2 by the piston 3 and then transferred to the condenser (not shown). A cycle in which the air is sent out, cooled and liquefied there, and then sent to an evaporator where it evaporates and removes the latent heat of vaporization from the surroundings to cool the indoor air, while the removed heat is released into the air (atmosphere) while passing through the condenser. It is made to repeat. However, when such a swash plate type compressor is used for a car cooler, the operating conditions are extremely severe. That is, the driving source is an internal combustion engine such as gasoline or diesel, and the compressor is designed to have a rotational speed almost the same as that of the internal combustion engine for the purpose of reducing the size and weight of the compressor and the compressor capacity. Therefore, the rotation speed of the swash plate compressor is subject to conditions ranging from approximately 500 rpm, which is the rotational speed of the internal combustion engine when it is idling, to approximately 6000 rpm, such as when driving at high speeds or accelerating suddenly. Additionally, although this problem is not limited to swash plate type compressors, as vehicles have become lighter in recent years, compressors themselves have been required to be smaller and lighter. As the amount of lubricating oil is reduced in order to improve the performance of the compressor, friction and wear are becoming more likely to occur in the sliding parts within the compressor. Furthermore, the increase in temperature in the engine room due to the installation of various devices in the engine room in recent years, such as exhaust gas control devices and devices to reduce fuel consumption, has an adverse effect on the lubricating oil in the compressor. It's disappearing. In a swash plate type compressor used under these conditions, the part most adversely affected by the above conditions is the sliding portion between the swash plate 5 and the shoe 6 shown in FIG.
The sliding speed is approximately 2 to 3 m/sec when the engine is idling, and approximately at maximum rotation.
This is because at 6000 rpm, it is 20 to 25 m/sec, and even during normal running, they slide at extremely high speeds of about 7 to 15 m/sec. In addition to such high-speed sliding motion, a load acts on the shoe to compress the medium to be compressed, such as refrigerant.
Its size is 60 to 130 Kg/cm ² , and although it is rare that both the sliding speed and pressure have the maximum combination, the PV value (pressure is PKg/cm ² and speed is Vm/
sec) can often exceed 2000. Moreover, this is repeated in relation to the rotational speed. The load that the shoe receives from this repetition becomes an impact load, especially at high speeds, and the extremely harsh conditions of sliding at high speed while receiving such impact load are necessary for the sliding part between the swash plate and the shoe. It happens. Furthermore, when looking at the sliding condition between the swash plate and shoe from the lubrication perspective, with the removal of the oil pump as mentioned above, the lubricating oil supplied to the sliding parts is only supplied in the form of a mist by mixing with the refrigerant gas. becomes.
This is because a swash plate type compressor without an oil pump is generally lubricated by carefully circulating refrigerant gas containing oil around each sliding part within the compressor, but in this case. This is because the amount of oil and the cooling capacity are inversely proportional to each other, so reducing the amount of oil is an effective means of increasing the cooling capacity of the swash plate compressor. From another perspective, it is the lubrication conditions that have the most influence on the life of the sliding parts of the swash plate and the shoe, and in particular, the amount of lubricating oil has the most influence. Therefore, in the midst of these contradictory relationships, what is particularly considered when designing a swash plate type compressor is the material of each of the swash plate and shoe that can meet the harshest sliding conditions. Furthermore, the sliding motion between the swash plate and shoe is a thrust sliding motion in which it is difficult to obtain a sufficient lubrication effect even if a sufficient amount of oil is supplied, so the sliding surfaces must always be under boundary lubrication. , or there is solid contact there, and this is a phenomenon that occurs because the swash plate compressor for a car cooler performs unsteady rotational movement that is inevitable in its use.
Lubricating oil is not supplied to the sliding surfaces between the swash plate and the shoe for several tens of seconds or even several minutes after startup, so during this period, the swash plate and shoe are completely unlubricated. It will be operated under conditions of solid contact. This situation can occur when refrigerant leaks from the pipes and the amount of refrigerant confined in the refrigeration cycle decreases, or when the amount of refrigerant returned to the compressor is caused by the operation of the evaporation pressure regulating device attached to the evaporator. It is also caused when the Therefore, among the various troubles that have occurred in swash plate type compressors to date, the most common problem is the seizure that occurs without lubrication from the time of startup, and the wear that occurs without lubrication can become a fatal defect. This caused burn-in to occur over time. Traditionally, swash plates have been made of structural materials that have mechanical rigidity, fatigue strength, and wear resistance, as materials that can withstand the above-mentioned lubrication conditions, as well as materials that can withstand the high surface pressure and impact loads mentioned above. Alloy steels such as nickel chrome steel, nickel molybdenum steel, chrome molybdenum steel, and spheroidal graphite cast iron were used, and the surface layer was hardened. In addition, the ball was mainly made of high carbon chromium steel in order to withstand high loads. The shoe materials include Algyl alloy, phosphor bronze, copper-lead-tin alloy, brass, high-strength brass alloy, bronze alloy, aluminum bronze alloy, Babitt metal,
Oil-impregnated bearing alloys were considered. However, none of the materials known to date have been able to fully satisfy the aforementioned extremely harsh operating conditions unique to swash plate compressors for car coolers. The applicants previously discovered that a bimetallic material made by sintering copper-lead-tin alloy powder on a steel plate is the only material that can extend the lifespan, and filed a patent application.
No. 49-109856, but even the material related to this application is not necessarily sufficient for swash plate type compressors, which require smaller size and higher performance, and cannot be said to be sufficient for swash plate compressors that require smaller size and higher performance. Therefore, it is desired to develop a material with a long life that has properties that are even more improved than conventional ones, such as excellent wear resistance that prevents seizure from occurring. -ing In view of the above circumstances, the inventors of the present invention have conducted various research and development and have found that the sliding speed is 2 to 2.
25m/sec repeated operation and surface pressure 130~140
It can withstand repeated shock loads of Kl/cm ² , and the supply of lubricating oil is extremely small, it is supplied in the form of a mist along with refrigerant gas, and it can withstand sliding without lubrication for several seconds to several minutes after startup. The present invention was completed by discovering an excellent alloy material and applying it to a sew material for swash plate type compressors, particularly car coolers. In other words, the present invention solves all of the problems of the conventional methods described above, by using a copper alloy that is strengthened to the extent that the thermal conductivity does not decrease too much, has little decrease in hardness especially at high temperatures, and has good sliding properties. The purpose of the present invention is to provide a swash plate compressor as described above, in which copper (Cu) is used as the main sew material, and elements from Group A of the periodic table and elements from Group A of the periodic table are used. The total amount of one or more elements selected from the group consisting of group A elements is 3% (by weight,
The purpose is to use a Cu alloy containing tin (Sn) in an amount not exceeding 5% (not including zero) and further containing less than 5% (not including zero) of tin (Sn). The Group A and Group A elements used in the present invention are mainly used to disperse precipitates caused by crystallization and precipitation phenomena in the Cu base material (matrix) to strengthen the matrix. By containing at least one kind of element, Cu is effectively strengthened, and moreover, 200
It not only provides heat resistance that does not reduce hardness even at high temperatures of 0.degree. C. or higher, but also improves its wear resistance. In particular, among the Group A and Group A elements, chromium (Cr) is most preferably used.
It is one or a combination of two or more of titanium (Ti) and zirconium (Zr), and the addition of Cr can increase the strength of the alloy by causing precipitation hardening. However, since excessive addition of Cr makes the entire alloy brittle, the appropriate blending ratio of Cr required to improve the strength during precipitation hardening is 3% or less. Furthermore, Ti has the effect of strengthening the alloy through heat treatment, and its precipitation can increase the hardness of the alloy. The appropriate proportion of Ti required to improve the strength during precipitation hardening is 3% or less. Furthermore, Zr can form intermetallic compounds with other alloying elements to strengthen the alloy, and such strengthening by intermetallic compounds can be achieved by introducing the elements separately in equal amounts into the composition of the intermetallic compound. It is even more effective than However, the amount of Zr added is 3%
If the amount exceeds 3%, the thermal conductivity will drop sharply, so in the present invention, the amount of Zr added is appropriately determined within a range not exceeding 3%. By the way, these examples do not mean that the group a and group a elements according to the present invention are limited to the above three types, and other elements such as molybdenum and tungsten can be used as well, and such elements can also be used. group a, group a
When two or more elements of the same group are used, the total amount should be within 3%. This is because addition of more than 3% in total may cause problems such as embrittlement of the entire alloy. Also,
Although it is difficult to unambiguously determine the lower limit of the amount of these Group A and Group A elements, since even a small amount of these elements can have some effect, it is generally Even if added, 2
Approximately 0.1% even if more than one element is added
(total amount), thereby achieving a sufficient improvement in mechanical strength. Furthermore, one or more of these Group A and Group A elements may be added in a total amount of 0.3 to 2%.
This is most preferred in the present invention. In addition, along with the elements of group a and group a,
Sn added to Cu not only strengthens the matrix by dissolving in Cu, but also lowers the friction coefficient in terms of sliding properties, and this friction coefficient maintains a stable low friction even at high temperatures. As a result, it exhibits an excellent effect on seizure resistance, especially under high-temperature conditions. However, since such added Sn dissolves in Cu as described above, it tends to reduce the thermal conductivity of the alloy, and therefore the range of its addition is limited. In this sense, 5% is adopted as the upper limit of Sn addition, and therefore the addition amount of Sn is determined as appropriate within the range of less than 5% (of course, zero is not included), and the appropriate addition amount. The most preferable content is 1 to 3%. Note that the addition of Sn is also effective in improving castability. Therefore, the alloy according to the present invention, in which Cu is used as a base material and the above-mentioned Group A and Group A elements and Sn are added thereto, has an alloy composition that has excellent properties as a shoe material. . However, when using a swash plate compressor sash for a car cooler when the amount of lubricating oil is small, the most important issue is the thermal conductivity of the sew, and the elements that have the greatest effect on that thermal conductivity are the added elements. Furthermore, a large increase in the coefficient of friction is a direct cause of heat generation, so it is important to strengthen the matrix and improve the sliding characteristics with as few additive elements as possible for swash plate compressor sashes for high-performance car coolers. This is because it is the key to whether or not you can adapt well. Since a certain amount of lubricating oil is supplied during so-called normal operation, although it is relatively small, it is important to improve thermal conductivity and effectively dissipate heat, especially for shoe materials, and to reduce hardness at high temperatures. Reducing the change in structure by reducing the amount of stress will affect the sliding characteristics of the shoe.
In this sense, it is important to add Sn to Cu together with group a and group a elements. Furthermore, even if the swash plate type compressor for high-performance car coolers is designed to eliminate the problem in a short time by improving the no-lubrication situation at startup, it will not be possible to eliminate it completely. Moreover, reductions in the amount of oil and refrigerant gas occur occasionally even during normal operation, and the material of the shoe is required to have various performances to be able to cope with these various conditions. Therefore, the selection and amount of additive elements according to the invention,
The degree of reinforcement and thermal conductivity resulting from this must be fully considered, and the most appropriate combination is Cu.
It is desirable to add at least one element selected from group a and group a and Sn together. In particular, in order to eliminate the harmful effects of having too many solid-solution elements, such as structural heterogeneity and decreased thermal conductivity due to intermetallic compounds, and brittleness caused by over-hardening of the matrix, we have developed a method that does not cause the above-mentioned harmful effects. By using the additive element by precipitation according to the present invention, which can be strengthened by precipitation, it is possible to expect resistance to seizure and wear resistance due to the precipitates, and it is possible to achieve this without significantly lowering the thermal conductivity. In addition,
Normally, when selecting a sliding material, the selection of the mating material is also important, and especially when the conditions are severe, the selection is more limited than the mating material. Under such circumstances, conventional sliding materials are relatively good if the mating material is Cr steel, Mn steel, etc., but this material is made of spheroidal graphite cast iron, which has poor sliding properties and is unsuitable as a mating material. Become. However, it has been confirmed that the shew material made of the Cu alloy according to the present invention can withstand even when the mating material is spheroidal graphite cast iron. In addition, according to the studies of the present inventors, the thermal conductivity required for a shoe material that can be used in a swash plate type compressor for a high-performance car cooler is 0.2 cal/cm ³ .
It is desirable that the temperature is sec・℃ or higher, and
It is more preferable that the hardness is 0.4 cal/cm ²・sec・℃ or more, and even if the hardness is 300℃
It has become clear that it is desirable to have a Vickers hardness (Hv) of 80 or more at high temperatures, but none of the Cu alloys according to the present invention have such desirable thermal conductivity and hardness. Therefore, it has an excellent effect. As a result, the following effects can be recognized in the Cu alloy according to the present invention. In other words, since the amount of added elements is significantly smaller than conventional shoe materials, it has good thermal conductivity and can easily dissipate the frictional heat generated even in long periods without lubrication. There is no softening of the material, which makes it less likely to cause seizure.
In addition, in the case of the present invention, there are fewer additive elements for strengthening than in the past, so it seems that sufficient strengthening is not achieved compared to the conventional material, but in the case of the conventional material, The copper alloy in this invention Although it was slightly better at room temperature, the overall strength was lower.
On the other hand, since the amount of added elements in the present invention is small, as a result, there is not much difference in strength compared to conventional materials. Furthermore, especially at high temperatures, the copper alloy of the present invention exhibits better values than conventional materials. Furthermore, in the case of the present invention, there is little decrease in hardness even under high temperatures.
By adding Sn (a solid solution element), the strength and hardness of the matrix do not decrease even when the shoe becomes high temperature due to frictional heat, etc., and it is in an extremely stable state. The Cu alloy of the present invention also contains nickel (Ni), iron (Fe), tellurium (Te),
Phosphorus (P), antimony (Sb), arsenic (As), etc. can be added in small proportions, and this mainly has the effect of improving strength or making the matrix finer, but these do not affect the effect of addition. It has its advantages and disadvantages, and it has been confirmed that its performance is considerably lower than that of Cr, Zr, Ti, and Sn. However, it has been confirmed that it can withstand use under certain conditions. Below, specific examples of the present invention will be shown in order to further facilitate understanding of the present invention. First, samples 1 to 5 were obtained by a casting method using the composition ratios shown in Table 1. The casting method is approximately 1250℃.
A method was adopted in which Cu was added, followed by alloying elements (Cr, Zr, Ti, and Sn), and the resulting material was heat treated at approximately 700°C for 2 hours to prevent segregation to obtain a Cu alloy material. In order to conduct actual machine tests using these obtained materials, each was processed to a diameter of 18 mm and a thickness of 4.5 mm to obtain a shoe. Further, this shoe has a spherical concave surface with a depth of about 3 mm so that a part of a ball with a diameter of about 14 mm is inscribed in the center. In addition,
Samples 10 to 17 having the alloy compositions shown in Table 2 were made as comparative materials by the same method as above, and samples 10 to 17 according to the present invention were prepared as comparative materials.
A comparison was made between Cu alloy and Shu. In addition, the hardness of Samples 1 to 5 at the time of final processing at room temperature was all Hv100 or higher. Furthermore, the thermal conductivity of each of the obtained samples was measured and shown in Table 3. As is clear from the sample table, each sample made of the Cu alloy of the present invention had excellent thermal conductivity. ing.

【table】

【table】

[Table] -Experiment 1- Using each sample in Tables 1 and 2, an experiment was conducted to measure the friction coefficient and the exothermic temperature at that time. The measurement method was to rotate a disc, press a shoe against it, and gradually increase the pressing load while measuring the coefficient of friction and the heat generation temperature of the shoe.

[Table] The results obtained are shown in Figures 2 and 3. In addition,
Figures 2 and 3 are part of the experimental results. Similar results were obtained for other samples 1, 3, and 5, although the performance was somewhat lower than that of samples 2 and 4. As is clear from FIG. 2, the sample based on the present invention has a lower coefficient of friction in all regions than the comparative material, and is stable even when the load is increased. Also, looking at the heat generation temperature of the shoe from Figure 3,
In the case of the sample according to the present invention, compared to the comparative sample,
It is declining in all areas. Furthermore, when these results are compared with the thermal conductivity of each sample in Table 3, all the samples of the present invention having a thermal conductivity above a certain level are good. Based on these facts, if the load is increased, the frictional resistance will naturally increase and heat will be generated.This heat generation will change the structure of the material, and the increase in the coefficient of friction will cause seizures.Thermal conduction Although this occurs in comparison samples with poor performance, even if heat is generated in the samples of the present invention, it has excellent heat dissipation properties, so the temperature of the entire shoe or the temperature near the sliding surface does not rise too much. Therefore, there are no phenomena such as structural changes or increases in the coefficient of friction, and it is stable in all areas. What is particularly noteworthy here is that even though the oil lubrication was not sufficient, the samples of the present invention performed well, which is of great significance. -Experiment 2- Next, an actual machine test was conducted under the most severe conditions for supplying lubricating oil, and the obtained results are shown in Table 4. The test conditions are as follows. (1) Compressor Swash plate type compressor (total displacement 150c.c.) (2) Rotation speed 4000r.pm (3) Discharge side gas pressure Pd = 4 to 5Kg/cm ² (4) Suction side gas pressure Ps = approx. 50mmHg (5) Operating time 20Hrs (6) Lubricating oil Refrigerator oil 150c.c. (7) Compatible material Spheroidal graphite cast iron (8) Gas amount 100g (approx. 10% of regular)

【table】

[Table] As is clear from Table 4, all of the samples according to the present invention showed no seizure at all and were all in good condition. In particular, since this experiment was performed under the most severe lubrication conditions that occur under normal operating conditions, the fact that it was satisfactory even under such conditions is proof of the superiority of the Cu alloy sample according to the present invention. It is. -Experiment 3- Next, as a load life experiment, an experimental test was conducted under conditions where poor lubrication is particularly likely to occur, and the results are shown in Table 5. The test conditions are as follows. (1) Compressor Swash plate compressor (total displacement 150c.c.) (2) Rotation speed 5500r.pm (3) Discharge side gas pressure Pd=20Kg/cm ² (4) Suction side gas pressure Ps=3Kg/cm ² (5) Operating time 400Hrs (6) Lubricating oil and amount Refrigerator oil 150c.c. (7) Continuous operation 25 seconds operation, 5 seconds rest (8) Compatible material Spheroidal graphite cast iron (9) Gas amount 1Kg

【table】

[Table] As is clear from Table 5, sample 1 according to the present invention
It was found that Samples No. 5 to No. 5 had no seizure phenomenon and had less wear than Comparative Samples Nos. 10 to 17, and were sufficiently usable. Since this experiment was conducted in a situation where almost no lubricating oil was present, the fact that it performed well indicates that seizure is unlikely. As detailed above, the present invention provides a compressor,
Particularly in swash plate type compressors for car coolers, lubricating oil is extremely low, and even if sufficient oil is not supplied to the sliding parts of the swash plate and shoe, or even if there is no lubrication for several minutes, the sliding properties of the mating material will improve. Even if it is made of spheroidal graphite cast iron, which has poor wear and tear, it can withstand use for an extremely long time by using a shew material made of a specific _Cu alloy that has little wear and tear and excellent thermal conductivity. This invention has great significance in that it provides a swash plate type compressor with a long life, and it has contributed greatly to improving the performance of compressors for car coolers in particular.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view for explaining the swash plate type compressor, and FIGS. 2 and 3 are graphs showing the friction coefficient and heat generation temperature results obtained in Experiment 1, respectively. 1: Cylinder block, 2: Cylinder bore,
3: Piston, 4: Shaft, 5: Swash plate, 6: Shoe, 7: Ball.

Claims (1)

[Claims] 1 A swash plate that is rotated by a rotating shaft within a cylinder block, and a piston that is moored to the swash plate via a shoe, so that the piston reciprocates within the cylinder bore in accordance with the rotation of the swash plate. In the swash plate type compressor made of A swash plate type compressor comprising a copper alloy containing not more than 3% of tin, and further containing less than 5% of tin.