JP4890111B2 - Thrust roller bearing - Google Patents

Description

  The thrust roller bearing (including the thrust needle roller bearing) according to the present invention is installed in a rotating portion of an electrical component such as a transmission of an automobile (manual and automatic), a transfer, or an air conditioner for an automobile, and the rotation Used to support the thrust load applied to the part.

  As shown in FIG. 8, the thrust roller bearing 1 has a plurality of rollers 2 radially arranged in the circumferential direction and a whole ring-shaped, and holds the plurality of rollers 2 in a rollable manner. The cage 3 is composed of a raceway ring that holds the plurality of rollers 2 from both sides, that is, an outer ring 4 and an inner ring 5. Each of the outer ring 4 and the inner ring 5 is formed in an annular shape by a metal plate having sufficient hardness. The outer ring 4 has an annular outer ring raceway surface 6, and the inner ring 5 has an annular inner ring raceway surface 7.

  The thrust roller bearing is a bearing having various advantages such as a simple structure and high load capacity and high rigidity. In some cases, the bearing ring is not used, and only a cage and a roller are used. In this case, the shaft or housing that is the rolling surface of the roller rolling surface has a function equivalent to the bearing raceway surface such as roughness and hardness, and by using the shaft or housing as the raceway surface, A bearing ring is not required and can be made compact. In particular, a thrust needle roller bearing using needle rollers as rollers can reduce the cross-sectional height of the bearing, and is particularly suitable for a compact mechanical design.

  A main application in which a thrust needle roller bearing, which is a typical example of a thrust roller bearing, is used is a compressor for an air conditioner for an automobile. There are various types of these compressors. For example, as shown in FIG. 5, a double swash plate type in which a piston 10 is reciprocated by a double-sided inclined plate 9 fixed to the input rotary shaft 8, and as shown in FIG. 7 is a single swash plate type in which a piston 14 is reciprocated through a rod 13 with a single-side inclined plate 12 fixed to 11, and further, as shown in FIG. There is a variable capacity swash plate type in which the piston 18 is reciprocated via each, and in each case, a rolling bearing is incorporated in the rotating part.

  In a specific example of bearing use, in the case of the swash plate type of FIG. 5, a needle roller bearing 19 with a cage and a thrust needle roller bearing 20 are used. The swash plate type of FIG. 6 uses a shell needle roller bearing 21 and a thrust needle roller bearing 22. Further, the variable capacity swash plate type of FIG. 7 uses a needle roller bearing 23 with a cage and a thrust needle roller bearing 24. As described above, the thrust needle roller bearing has advantages such as a low cross-sectional height, and therefore is used for applications such as compressors that require space saving.

  In general types of bearings (for example, ball bearings, etc.), differential slip occurs between the rolling elements and the races. Basically, the differential slip of these bearings is basically different between the rolling elements and the raceway. It depends on the peripheral speed difference in the contact surface of the ring. That is, in the case of point contact such as a ball bearing, since the contact area is small, the peripheral speed difference in the contact surface is small and the differential slip is small.

  However, a thrust roller bearing has a structure in which a roller having a cylindrical shape is arranged as a rolling element on a raceway having a flat raceway surface, and the roller and the raceway are in line contact with each other. The basic structure is to match the center of revolution of the roller. In this case, the peripheral speed on the rolling surface of the roller is the same speed. On the other hand, the bearing ring that is in rolling contact with the roller moves from the center of rotation of the bearing toward the outer diameter direction (proportional to the rotation radius of the bearing ring). ), The peripheral speed becomes faster. Therefore, the difference in the circumferential speed between the roller and the raceway is maximized at both ends of the roller. Theoretically, pure rolling motion is performed only on the pitch circle of the bearing, and the circumferential speed difference between the roller and the bearing ring increases from the point on the roller pitch circle toward both ends of the roller, increasing the differential slip. To do. This differential slip increases in proportion to the length of the roller.

  As described above, the differential slip inside the bearing in the thrust roller bearing is much higher than that of other types of bearings, and the differential slip between the roller and the bearing ring is a factor. Edge stress is likely to occur, and surface-origin type peeling is likely to occur at the edge of the rolling part of the race.

As means for solving the above-mentioned problems, a double row type bearing in which a roller length is shortened in order to reduce the relative sliding amount of the roller end face, or two rollers are put in one pocket of a cage. in use. Further, for the problem that stress (edge load) is generated at the roller end, measures such as forming crowning on the roller are taken.
Japanese Patent Laid-Open No. 9-14131

  Thrust roller bearings are required to be reduced in size due to demands for energy saving, space saving, weight reduction, etc. (reduction of friction loss). Therefore, the bearing use conditions are becoming more severe in terms of load capacity. As described above, in the thrust roller bearing, differential slip between the roller and the raceway causes a friction loss and wear on the contact surface, and the oil film formation state on the contact surface deteriorates, and the roller edge In this portion, an edge stress between the bearing ring is likely to occur, and surface-origin type peeling is likely to occur at the edge of the rolling part of the bearing ring. In order to suppress differential slip, it is conceivable to simply shorten the roller length, but the contact surface pressure increases because the contact area of the roller decreases, and in that case the contact surface pressure at the contact surface Becomes higher, the oil film formation state deteriorates, and problems such as occurrence of peeling on the roller outer diameter side occur.

  The bearing used in the compressor is in a state where the lubricant and refrigerant of the bearing are mixed inside. The compressor is compressed and expanded, and the liquefaction and vaporization of the lubricant is repeated. There is a problem that the amount of oil is reduced, and an oil film formation state is poor as compared with the lubricating oil lubrication of a general machine, and there arises a problem that peeling occurs early.

  Further, from the viewpoint of environmental problems such as prevention of global warming, alternative chlorofluorocarbons such as HCFC134a are used as refrigerants in compressors for air conditioners and the like. These alternative chlorofluorocarbons are said to have poor self-lubricating properties as compared with refrigerants conventionally used. Since it is in a mixed state by dissolving with alternative chlorofluorocarbon, the kinematic viscosity of the lubricating oil decreases, and the oil film formation state of the bearing deteriorates so much that peeling and wear on the rolling elements and bearing rings of the bearing There is a problem that surface damage such as the above occurs, resulting in a short life.

  Although a method for improving the lubricating oil is conceivable, the selection range of the lubricating oil is limited due to the compatibility with the refrigerant, and a significant improvement in the ability to form an oil film cannot be expected. Further, in the method of increasing the amount of lubricating oil in the refrigerant and improving the lubricity, there is a problem that the cooling capacity of the compressor is lowered due to a decrease in the amount of the refrigerant.

  Thrust needle roller bearings used in air conditioner compressors are subjected to a thrust load offset from the center of rotation, have a high rotational speed of about 8000 rpm or more, and are severe conditions in terms of rotational speed and load conditions. There is an increasing number of failure phenomena that indicate surface damage of bearings due to differential sliding.

  The object of the present invention is to reduce the differential slip, reduce friction wear, have excellent peeling resistance life, and further suppress the decrease in load capacity and increase in contact surface pressure in the thrust roller bearing in view of the above situation. It is to provide a thrust roller bearing.

A thrust roller bearing according to the present invention includes a plurality of rollers having the same shape and size arranged in a plurality of roller rows in the radial direction, and a cage that holds the rollers. The rollers are needle rollers. In the thrust roller bearing, symmetrical crownings are formed at both ends of all the rollers arranged in a plurality of roller rows. The cage has one pocket common to the plurality of roller rows in the radial direction. All the rollers of each of the plurality of roller rows are held in the common pocket. The rollers held in the pockets of the cage are arranged side by side so that the end faces of the adjacent rollers face each other. Of the plurality of rollers held in a common pocket, the opposing end surfaces of the adjacent rollers are in direct contact with each other.

  In the above thrust roller bearing, the roller shape may be determined so that the ratio L / Da of the roller length L to the diameter Da satisfies the relationship 1 ≦ L / Da ≦ 10.

  The thrust roller bearing according to the present invention is a thrust roller bearing comprising a plurality of rollers arranged in at least two rows in the radial direction and a cage for holding the rollers, wherein at least one of the rollers is provided. A thrust roller bearing characterized in that a crown is formed on the roller. In this configuration, the effect of reducing the differential slip due to the double row roller and the effect of reducing the differential slip by shortening the effective length of the roller by adding the crowning shape, and the crowning shape There is an effect that the load at the edge portion is reduced. At the same time, there is an effect of reducing the friction torque of the bearing.

  The thrust roller bearing is a thrust roller bearing having a configuration in which one roller is held in each pocket of the cage. According to this configuration, since one roller is held by one pocket of the cage, the roller can be stably held and roller skew can be prevented. Also, the friction torque generated due to the roller skew can be reduced.

  The thrust roller bearing is a thrust roller bearing having a configuration in which the rollers of the outer diameter side are formed with a smaller amount of crowning than the innermost side roller array in the crowning of the rollers. According to this configuration, since the effective length of the roller on the outer diameter side is increased, the contact surface pressure can be suppressed, and the outer diameter side of the roller array on the outer diameter side is peeled off. Prevent side ring separation.

  The thrust roller bearing is a thrust roller bearing configured such that in the crowning of the roller, at least one row of rollers on the outer diameter side is a straight roller rather than the roller on the innermost side. According to this configuration, as in the third invention, the effective length of the roller on the outer diameter side is increased, so that the contact surface pressure can be suppressed, and the outer-diameter side roller row is peeled off and Prevents raceway ring separation on the outer diameter side of the radial roller train.

  The thrust roller bearing is a thrust roller bearing having a configuration in which the length of at least one roller on the outer diameter side is longer than the innermost roller row of the roller. According to this configuration, it is possible to reduce the relative slip of the inner diameter side roller row and increase the load capacity of the outer diameter side roller row, and to peel the outer diameter side roller row and to remove the outer diameter side roller row from the outer side. Prevents radial raceway separation.

  The thrust roller bearing is a thrust roller bearing having a configuration in which at least one end face of the roller has a spherical shape. According to this configuration, the interference between the end surfaces of the rollers and the interference between the roller end surfaces and the cage pocket portion are reduced, and the skew of the rollers can be reduced. Also, the friction torque generated due to the roller skew can be reduced.

  The thrust roller bearing further comprises a thrust roller having a configuration in which the number of rollers in at least one row on the outer diameter side of the roller row on the innermost side is equal to or more than the number of roller rows on the innermost side. It is a bearing. According to this configuration, it is possible to increase the load capacity in the outer diameter side roller train, and prevent the outer diameter side roller train from peeling off and the outer diameter side roller row from peeling off the outer ring side.

  The thrust roller bearing is configured such that the thrust roller bearing is used by being incorporated in a compressor. In the compressor, as described above, space saving is required, and deterioration of the oil film formation state of the thrust roller bearing under the specific lubrication conditions including the refrigerant can be suppressed. It also has an effect.

The present invention has the following effects.
Double row roller reduces the effect of differential slip and synergizes the effect of shortening the effective length of the roller by forming crowning to reduce differential slip, and also loads at the edge of the crowning shape Has the effect of being reduced. At the same time, there is an effect of reducing the friction torque of the bearing. Further, the rollers can be stably held by the cage, and the skew of the rollers can be prevented. Also, the friction torque generated due to the roller skew can be reduced. Further, the contact surface pressure of the outer diameter side roller can be suppressed, and the outer diameter side roller row is prevented from peeling off and the outer diameter side roller row is prevented from peeling off. Further, the interference between the end surfaces of the rollers and the interference between the roller end surfaces and the cage pocket portion are reduced, and the skew of the rollers can be reduced. Also, the friction torque generated due to the roller skew can be reduced. In addition, it is possible to reduce the differential slip of the inner diameter side roller array and increase the load capacity of the outer diameter side roller array. Prevent raceway ring peeling.

  Embodiments of the present invention will be described below. Fig.4 (a) is a figure which shows the shape of the roller 2a which formed crowning. For the roller 2a having the roller length L, a crowning having a length a is formed at both end portions thereof. By forming the crowning on the roller, the differential slip can be reduced by reducing the load on the edge (reducing edge stress) and shortening the effective length of the roller (straight portion b).

  FIG. 4B shows a configuration in which both end faces of the roller are spherical. With this configuration, the edge stress due to contact with the inner surface of the pocket inside the pocket surface of the cage is reduced, and the interference between the roller end surfaces and between the roller end surface and the cage pocket is reduced. This makes it possible to reduce skew. Also, the friction torque generated due to the roller skew can be reduced. Usually, the spherical shape is ± 50% of the roller diameter Da.

  FIG. 4C shows a configuration that does not employ the crowning shape, that is, a straight roller, unlike the configuration of FIG. When the crowning shape is not employed, the length of the straight portion of the roller can be increased, and the contact surface pressure can be reduced particularly under the condition that no inclination of the rolling surface occurs. In the present invention, straight rollers are used in at least one row on the outer diameter side of the innermost roller row of the rollers arranged in double rows. In addition, the material of these rollers is normally bearing steel and surface hardness HRC60-65 is used.

  FIG. 1A shows a form according to a first embodiment of the present invention. Rollers 2a having crowns formed at both ends in each pocket of a cage having one pocket row are arranged in two rows in the radial direction. It is a thrust roller bearing which formed the crowning accommodated in. FIG. 1B is a reference example of the present invention, and is a thrust roller bearing in which two pocket rows of the cage are held and one roller having a crowning formed therein is held. FIG. 1 (c) is another reference example of the present invention, in which the number of rollers in at least one row on the outer diameter side is the same as that in the innermost row than the row on the innermost diameter side of the roller. Alternatively, a thrust roller bearing having a larger number is shown, and the load capacity of the roller row positioned in the outer diameter direction can be made larger than that of the inner diameter side row.

  A life test was conducted using the thrust roller bearing having the above-described configuration. That is, by the above means, the friction slip and wear inside the bearing can be reduced by reducing the differential slip on the roller end face and reducing the stress concentration near the roller end, and the peeling life of the rolling edge can be improved. The effect was verified by a life test.

  For the life test, a roller diameter: φ3 mm, bearing ring inner diameter: φ65 mm, bearing ring outer diameter: φ85 mm bearing, test temperature: 60 to 80 ° C., load: 1000 kgf, rotation speed: 5000 rpm, lubricating oil: spindle oil VG2 (Oil film parameter, lambda: 0.101). The test results are shown in Table 1 together with comparative examples (standard rollers and thrust needle roller bearings using standard cages). The life is expressed as 10% life of 10 test bearings. The roller length was 7.8 mm for one row and 3.8 mm × 2 for two rows, and the crowning amount (drop amount) was 5 to 15 μm. In the life determination, the time when any member of the bearing peeled was defined as the life.

  From the results shown in Table 1, assuming that the life of sample 1 (standard bearing) as the first comparative example is 1, the sample 2 with the double row roller specification is 2.5 times as long as the sample 1, and is a crowning roller (single row roller). One sample 3 has a life of 4.9 times that of sample 1, whereas the life of sample 4, which is the first embodiment in which the crowning is formed by two rows of rollers, is 7.5 times that of sample 1. As a result, the lifetime was remarkably improved as compared with Sample 1 and Sample 2. Moreover, no peeling occurred at the time after the test. In addition, the current consumption of the motor under test was the lowest in sample 4 compared to 3.9A, indicating that the bearing had low torque, and that the friction loss inside the bearing was reduced. I understand.

  From the above results, the thrust roller bearing in which two or more rows of return rollers have a crowning formed on the roller has reduced friction loss and wear, and improved the surface-origin type peeling life generated at the edge of the rolling track, It is clear that there is an effect of preventing the peeling that occurs on the outer diameter of the roller.

  Next, Table 2 shows the test results obtained by using the rollers in which two rows of crownings are formed and changing the effective length and end face shape of the rollers. By providing two or more pockets in the radial direction of the cage (first reference example, sample 5), it is possible to prevent the rollers from interfering with each other, improve the retainability of the rollers by the cage, and reduce the roller skew. Thus, friction loss and wear are reduced, and the peeling life is improved (life ratio of 10% life is 1.5).

  When two or more reverse rollers are used, the inner diameter side row is crowned and the outer diameter side row is smaller than the inner diameter side row (second embodiment, sample 6), and only the outer diameter side row is a straight roller. (Second reference example, sample 7), by suppressing the contact surface pressure of the roller in the outer diameter side row than the inner diameter side row, it is possible to prevent the roller outer diameter peeling and the raceway outer diameter side peeling. It is clear from the test results that the life is improved.

  The roller length of the inner diameter side row was shortened, and the roller length of the outer diameter side row was made longer than that of the inner diameter side row (third embodiment, sample 8, in this case, compared to the two row rollers of the other embodiments) The inner side roller is shorter and the outer side roller is longer)) by increasing the load capacity of the outer side than the inner side, thereby separating the roller outer diameter and In addition to preventing the peeling of the roller, the differential sliding of the rollers on the inner diameter side row was reduced, and the life was improved (the life ratio of 10% life was 1.5). Also, from these results, the load capacity on the outer diameter side can be increased by setting the number of rollers (number of pockets) in the circumferential direction of the outer diameter side row to be the same as or greater than that of the inner diameter side row. However, it is clear that the same effect is obtained [FIG. 1 (c)].

  Further, by making the roller end face spherical (fourth embodiment and third reference example, samples 9 and 10), the interference between the end faces of the rollers and the interference between the roller end face and the cage pocket is reduced, and the life of the roller is reduced. The improvement (the life ratio of 10% life was 1.3, 1.6) was noticeable. Further, since the motor consumption current is lower than those of Samples 4 and 5, respectively, it is clear that there is an effect of reducing friction such as roller skew and reducing the torque of the bearing. In all of Examples 1 to 4 and 1st to 3rd Reference Examples (Sample 4 to 10), the motor current consumption tends to be lower than that of the Comparative Example, and the friction loss inside the bearing This indicates that the bearing torque is low.

  2 and 3 show an embodiment relating to the shape of the cage according to the present invention. FIG. 2 shows a first embodiment of the present invention in which a resin molded cage by injection molding is used and needle rollers are used as rollers. In this embodiment, the cage 3 can be formed into a complicated pocket shape by injection molding. As shown in FIG. 2 (b), each pocket holds two (two rows) rollers, and a protrusion is provided at the center to prevent the rollers from falling off. As shown in FIG. 2C, the retainer 3 can hold the roller 2 by this protrusion.

  FIG. 3 shows a first embodiment of the present invention in which a box type iron plate press cage formed by press molding or the like is used and needle rollers are used as rollers. In this embodiment, the cage can be produced at low cost by press molding. As shown in FIG. 3 (c), the two members 3a and 3b press-formed with an iron plate are assembled into a box shape by sandwiching the two rollers 2 in one pocket portion. It is done. Since the pocket has a width dimension that is smaller than the roller diameter, the cage 3 can hold the roller 2.

  When the dimensions of the rollers used in the needle roller bearings in the embodiments of FIGS. 2 and 3 are the roller diameter Da and the roller length L, they are defined as Da ≦ 5 mm and 1 ≦ L / Da ≦ 10. It is preferable. That is, when L / Da <1, the roller length is shortened, the effective length of the roller is also shortened, and the contact area of the roller is reduced, so that the contact surface pressure is increased. In that case, there is a problem that the contact surface pressure at the contact surface becomes high, the oil film formation state deteriorates, and problems such as occurrence of peeling on the roller outer diameter side occur. On the other hand, in the case of 10 <L / Da, when the roller length is increased, the effective length of the roller is also increased, and the differential slip between the roller and the raceway surface is increased. There is a problem that edge stress between the roller ring and the bearing ring is likely to be generated at the edge portion of the roller, and surface-origin type peeling occurs at the edge portion of the rolling part of the track ring.

(A) is a top view of the upper half of the thrust roller bearing according to the first embodiment of the present invention, in which two rows of rollers are held in one pocket of the cage, and (b) is a reference example of the present invention. FIG. 2 is a plan view of the upper half of a thrust roller bearing in which one roller is held in each of two rows of pockets of the cage, and FIG. 2 (c) is a plan view of the cage 2 according to another reference example of the present invention. FIG. 3 is a plan view of the upper half of a thrust roller bearing in which one roller is held in each row pocket and the number of rollers in the outer diameter side row is larger than that on the inner diameter side. (A) is a top view of the thrust needle roller bearing which uses the resin molding retainer for the retainer based on 1st Example of this invention, (b) is the A section enlarged view in (a) figure. (C) is a BB arrow sectional view (descriptive drawing of a pocket part) in the figure (b). (A) is a top view of the thrust needle roller bearing which uses the box-type iron plate press retainer for the retainer based on 1st Example of this invention, (b) is C- in FIG. It is C arrow sectional drawing, (c) is an enlarged view of the pocket part in (b) figure. (A) is explanatory drawing of the roller which formed the crowning which concerns on this invention, (b) is the roller which formed the crowning which concerns on 4th Example and 3rd reference example of this invention, and an end surface (C) is explanatory drawing of the roller which formed only the straight part based on the 5th comparative example of this invention. It is a longitudinal section showing a swash plate type compressor for an air conditioner. It is a longitudinal section showing a swash plate type compressor for an air conditioner. It is a longitudinal section showing a variable capacity swash plate type compressor for an air conditioner. (A) is a longitudinal cross-sectional view which shows the thrust roller bearing which concerns on the conventional embodiment, (b) is a top view of the upper half of the roller 2 and the holder | retainer 3 in (a) figure.

Explanation of symbols

  1 Thrust roller bearing, 2 rollers, 2a Roller with crowning, 2b Roller with crowning, spherical surface on the end face, 2c Roller with only straight part, 3 Cage, 3a Cage upper part 3b Cage lower part, 4 outer ring, 5 inner ring, 6 outer ring raceway surface, 7 inner ring raceway surface, 8 input rotating shaft, 9 double-sided inclined plate, 10 piston, 11 input rotating shaft, 12 single-sided inclined plate, 13 rod, 14 Piston, 15 Input rotary shaft, 16 Swash plate, 17 Rod, 18 Piston, 19 Needle roller bearing with cage, 20 Thrust needle roller bearing, 21 Shell needle roller bearing, 22 Thrust needle roller bearing, 23 Holding Needle roller bearing with vessel, 24 thrust needle roller bearing, 25 crowning.

Claims (3)

In a thrust roller bearing comprising a plurality of rollers of the same shape and size arranged in a plurality of roller rows in the radial direction, and a cage for holding the rollers,
The roller is a needle roller,
Forming symmetric crowning at both ends of all the rollers arranged in the plurality of roller rows,
The retainer has one pocket common to the plurality of roller rows in the radial direction,
Each one of the rollers in each of the plurality of roller rows is held in the common single pocket,
The rollers held in the pockets of the cage are arranged side by side so that end faces of the adjacent rollers face each other ,
A thrust roller bearing in which the opposed end surfaces of the adjacent rollers among the plurality of rollers held in the common pocket are in direct contact with each other . 2. The thrust roller bearing according to claim 1, wherein a shape of the roller is determined so that a ratio L / Da of a length L of the roller to a diameter Da satisfies a relationship of 1 ≦ L / Da ≦ 10. . The thrust roller bearing according to claim 1 or 2 , wherein the thrust roller bearing is used by being incorporated in a compressor.

Images