JP2006038074A - Bearing for compressor for air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve long life under conditions of low viscosity, dilute lubrication, and extremely low oil film thickness. <P>SOLUTION: In the surface of at least a rolling element in a bearing for a compressor for an air conditioner, a number of micro-dents are provided at random. A surface roughness parameter Ryni for the surface provided with the micro-dents is in a range of 0.4-1.0 μm, and a value Sk is set at -1.6 or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bearing used in an air conditioner compressor.

  There are various types of air conditioner compressors. For example, as shown in FIG. 10, a double swash plate type in which a piston 38 is reciprocated by a double-sided inclined plate 36 fixed to an input rotary shaft 34, as shown in FIG. A single swash plate type in which the piston 50 is reciprocated through a rod 48 with a single-sided inclined plate 46 fixed to the input rotary shaft 44, and further, as shown in FIG. 12, a swash plate 56 attached to the input rotary shaft 54 with variable angle. There is a variable capacity swash plate type in which the piston 60 is reciprocated through a rod 58. There are also scroll and vane types. Each type incorporates a rolling bearing in the rotating part in any case.

  Specifically, in the case of the double swash plate type of FIG. 10, a needle roller bearing 40 with a cage and a thrust needle roller bearing 42 are used. In the swash plate type of FIG. 11, a shell needle roller bearing 52 and a thrust needle roller bearing 42 are used. In the variable capacity swash plate type of FIG. 12, a needle roller bearing 40 with a cage and a thrust needle roller bearing 42 are used.

The compressor used in the air conditioner as described above is in a state where the lubricant and refrigerant of the bearing are mixed inside, and the liquefaction and vaporization of the lubricant are repeated by the compression and expansion of the compressor, and the lubrication of the bearing is performed. As compared with general hydraulic oil, it is in severe conditions.
JP-A-4-265480 (paragraph number 0012, FIG. 1)

  As described above, the bearing used in the compressor of the air conditioner has a poor lubrication state compared to general hydraulic oil lubrication because the refrigerant is mixed in and the amount of lubricant is reduced, and the rolling surface. Peeling damage occurs, and the problem of early peeling occurs.

  Japanese Patent Application Laid-Open No. 4-265480 discloses a roller bearing in which minute irregularities are formed on the surface of a rolling element to improve the oil film forming ability. These indentations of the minute concave shape have a value Rqni (L) / value of the ratio of the axial surface roughness Rqni (L) and the circumferential surface roughness Rqni (C) when the surface roughness is expressed by the parameter Rqni. The value of Rqni (C) is 1.0 or less (Rqni ≧ 0.10), and the surface roughness parameter Sk is set to −1.6 or less, so that even if the mating surface is rough, Even if the finished surface is good, it has a long life, but if the oil film thickness is extremely thin under low viscosity and dilute lubrication, the effect may not be fully exhibited.

  In the air conditioner compressor bearing according to the present invention, an infinite number of minute concave recesses are provided at least on the surface of the rolling element, and the surface roughness parameter Ryni of the recesses is 0.4 μm ≦ Ryni ≦ 1. It is within the range of 0.0 μm and the Sk value is −1.6 or less. By adopting such a configuration, the oil film formation rate on the rolling surface is improved, and even under severe lubrication conditions, no peeling damage occurs on the rolling surface and a long life can be obtained.

  Here, the parameter Ryni is the average value of the maximum height for each reference length, that is, the reference length is extracted in the direction of the average line from the roughness curve, and the interval between the peak line and the valley bottom line of this extracted portion is the roughness curve. It is a value measured in the direction of the vertical magnification (ISO 4287: 1997).

  The parameter Sk indicates the degree of skewness (skewness) of the roughness curve (ISO 4287: 1997), and is a statistic that is a measure of the asymmetry of the uneven distribution. The Sk value is close to 0 in a symmetric distribution such as a Gaussian distribution. That is, when the concave and convex portions are deleted, negative values are obtained, and in the opposite case, positive values are obtained. The Sk value can be controlled by selecting the rotational speed of the barrel sander, the processing time, the amount of workpiece input, the type and size of the chip, and the like. By setting the Sk value to -1.6 or less in both the width direction and the circumferential direction, the hollow with a minute concave shape becomes an oil reservoir, and even when compressed, there is little oil leakage in the sliding direction and the right-angle direction, so that an oil film is formed. Excellent, oil film formation is good, and has the effect of minimizing surface damage.

  As is well known, a rolling bearing is a mechanical element that supports a shaft that rotates or swings by a rolling motion of a rolling element (ball or roller). Usually, the rolling element is movably interposed between the race of the inner ring and the race of the outer ring, but there is a type that does not have an inner ring with the outer peripheral surface of the shaft as a direct race surface. The reason why at least the surface of the rolling element is used is that it does not exclude the formation of a concave indentation on the raceway surface as well, and when the rolling element is a roller, not only on the rolling surface but also on the end surface. The purpose of this is not to exclude those formed with micro-dents.

  According to a second aspect of the present invention, in the air conditioner compressor bearing of the first aspect, a surface roughness parameter Rymax of the surface provided with the recess is 0.4 to 1.0. The parameter Rymax is the maximum value of the maximum height for each reference length (ISO 4287: 1997).

  According to a third aspect of the present invention, in the bearing of the compressor for an air conditioner according to the first aspect, when the surface roughness of the surface provided with the recess is indicated by a parameter Rqni, the axial surface roughness Rqni (L) and the circumferential direction The ratio value Rqni (L) / Rqni (C) to the surface roughness Rqni (C) is 1.0 or less. The parameter Rqni is the square root of the value obtained by integrating the square of the height deviation from the roughness center line to the roughness curve in the section of the measurement length and averaging it, and is also called the root mean square roughness. . Rqni is obtained by numerical calculation from the cross-sectional curve and roughness curve recorded in an enlarged manner, and measured by moving the stylus of the roughness meter in the width direction and the circumferential direction.

  According to the present invention, an oil film forming ability is improved by providing an innumerable number of minute concave concaves on the surface of the rolling element, and the oil film thickness is extremely thin under low viscosity and dilute lubrication. But it has a long life. In particular, the surface roughness parameter Ryni of the surface provided with the indentation is set within a range of 0.4 μm ≦ Ryni ≦ 1.0 μm, and is suppressed to be smaller than before, thereby preventing oil film breakage even under lean lubrication. It is possible, and a long life can be obtained even under conditions where the oil film thickness is extremely thin compared to conventional products. As for the Sk value, -1.6 or less is the range advantageous for oil film formation in terms of the shape and distribution of the surface recess depending on the processing conditions.

  The rolling bearing used in the air conditioner compressor shown in FIGS. 10 to 12 has an inner ring, an outer ring, and rolling elements as main components. And, at least one of the rolling surfaces and end surfaces of the rolling elements and the raceway surfaces of the inner and outer rings are indented randomly and innumerably into a small rough surface. This minute rough surface has a surface roughness parameter Rqni of a surface provided with a depression within a range of 0.4 μm ≦ Rqni ≦ 1.0 μm, and an Sk value of −1.6 or less, preferably −4.9. It is the range of -1.6. Further, the surface roughness parameter Rymax of the surface provided with the depression is 0.4 to 1.0. Further, when the surface roughness is obtained in the axial direction and the circumferential direction of each surface and displayed by the parameter Rqni, the ratio of the axial surface roughness Rqni (L) to the circumferential surface roughness Rqni (C) The value Rqni (L) / Rqni (C) is 1.0 or less. As the surface processing for obtaining such a fine rough surface, a desired finished surface can be obtained by special barrel polishing, but a shot or the like may be used.

The measurement method and conditions of the parameters Ryni, Rymax, Sk, Rqni are exemplified as follows. Note that when measuring the surface properties represented by these parameters for components such as rolling elements and races of roller bearings, a single measured value can be relied on as a representative value. Should be measured.
Parameter calculation standard: JIS B 0601: 1994 (Surfcom JIS 1994)
Cut-off type: Gaussian Measurement length: 5λ
Cut-off wavelength: 0.25mm
Measurement magnification: × 10000
Measurement speed: 0.30 mm / s
Measurement location: Roller center measurement number: 2
Measuring device: Surface roughness measuring device Surfcom 1400A (Tokyo Seimitsu Co., Ltd.)

  FIG. 1 shows an example of a bearing for an air conditioner compressor. The bearing 1 is a needle roller bearing in which a needle roller 2 is incorporated in an outer ring 3 as a rolling element so that the needle roller 2 supports a counter shaft 4. It has become. A description will be given of the results of manufacturing a plurality of types of needle roller bearings having surface treatments with different finishing surfaces on the surface of the needle rollers and performing a life test. As shown in FIG. 2, the needle roller bearing used in the life test has 15 outer diameters Dr = 33 mm, an inner diameter dr = 25 mm, a diameter D = 4 mm of the needle roller 2, and a length L = 25.8 mm. It is a bearing with the cage | basket 5 using the needle roller of this. Three types of test roller bearings with different surface roughness finishes were produced. That is, there are a bearing A (comparative example) subjected to superfinish after grinding, and a bearing B (comparative example) and a bearing C (example) in which numerous indentations of minute concave shapes are randomly formed. FIGS. 3 to 5 show the finished surface condition of the needle roller of each test bearing. 3 shows the surface roughness of the bearing A, FIG. 4 shows the surface roughness of the bearing B, and FIG. 5 shows the surface roughness of the bearing C. Table 1 shows a list of characteristic value parameters of the surface finish of each test bearing. For Rqni (L / C), the bearings B and C are 1.0 or less, and the bearing A is a value around 1.0.

The test apparatus used is a radial load tester 11 as schematically shown in FIG. 6, and the test bearings 1 are attached to both sides of the rotating shaft 12, and the test is performed by applying rotation and load. The finish of the inner race (mating shaft) used for the test is Ra 0.10 to 0.16 μm of the polished finish. The outer race (outer ring) is also common. The test conditions are as follows.
Bearing radial load: 2000kgf
Rotation speed: 4000rpm
Lubricant: Crisef Oil H8 (2 cst under test conditions)

  FIG. 7 shows the life test results under the oil film parameter Λ = 0.13. The vertical axis of the figure represents the L10 life (h). As is clear from the figure, bearing A was 78h and bearing B was 82h, while bearing C was 121h. As shown by this data, the bearing C as an example can obtain a long life effect even under extremely severe lubricating conditions with a low viscosity and a thin oil film parameter Λ = 0.13.

  A peeling test was performed using a two-cylinder testing machine shown in FIG. 9 to evaluate the metal contact rate. In FIG. 9, a driving side cylinder 22 (D cylinder: Driver) and a driven side cylinder 24 (F cylinder: Follower) are attached to one end of each rotating shaft, and two rotating shafts 26, 28 are pulleys 30, 32, respectively. Can be driven by a separate motor. The shaft 26 on the D cylinder 22 side was driven by a motor, and the F cylinder 24 was free-rolled to follow the D cylinder 22. For the F cylinder 24, two types of comparative examples and examples were prepared for the surface treatment. Details of the test conditions are shown in Table 2.

  The comparison data of metal contact ratio is shown in FIG. In this figure, the horizontal axis represents the elapsed time, the vertical axis represents the metal contact rate, FIG. 8B shows the metal contact rate of the rolling surface of the roller in the bearing of the example, and FIG. 8A shows the bearing of the comparative example. The metal contact ratios of the rolling surfaces of the rollers are shown respectively. Comparing these figures, it can be clearly confirmed that the metal contact ratio is improved in the embodiment as compared with the comparative example. In other words, the oil film formation rate (= 100% −metal contact rate) is about 10% at the start of operation and 2 at the end of the test (after 2 hours) in the bearing of the example compared to the bearing of the comparative example. % Improvement.

Cross section of needle roller bearing Cross section of needle roller bearing used for life test Roughness curve diagram showing the condition of the finished surface of the rolling element in the test bearing Roughness curve diagram showing the condition of the finished surface of the rolling element in the test bearing Roughness curve diagram showing the condition of the finished surface of the rolling element in the test bearing Schematic diagram of test equipment Graph showing life test results A is a graph showing the metal contact rate of the comparative example, and B is a graph showing the metal contact rate of the example. Overall schematic diagram of a 2-cylinder testing machine Cross section of double swash plate type compressor Cross section of swash plate type compressor Cross section of variable displacement swash plate type compressor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing 2 Rolling element 2a Indentation 3 Outer ring 4 Opposite shaft 5 Cage

Claims (3)

  At least the surface of the rolling element is randomly provided with an infinite number of minute concave recesses, and the surface roughness parameter Ryni of the surface provided with the recesses is in the range of 0.4 μm ≦ Ryni ≦ 1.0 μm, and Sk An air conditioner compressor bearing having a value of -1.6 or less.   The bearing for a compressor for an air conditioner according to claim 1, wherein a surface roughness parameter Rymax of the surface provided with the recess is in a range of 0.4 to 1.0.   When the surface roughness of the surface provided with the depression is represented by the parameter Rqni, the value Rqni (L) / Rqni (R) of the ratio between the axial surface roughness Rqni (L) and the circumferential surface roughness Rqni (C) 2. The air conditioner compressor bearing according to claim 1, wherein C) is 1.0 or less.

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