JP2006002820A - Roller bearing with double row thrust needle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller bearing with double row thrust needle capable of achieving long service life even under severe lubrication conditions. <P>SOLUTION: This double row thrust needle roller bearing is constituted by arranging a plurality of rollers in the radial direction of a bearing. Carburizing nitriding treatment is applied to both an outer side roller 3 positioned on an outer side in the radial direction and an inner side roller 2 positioned on an inner side in the radial direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a double-row thrust needle roller bearing, and more particularly to a double-row thrust needle roller bearing used in a compressor for an air conditioner, an automatic transmission, an electric brake, or the like of an automobile.

  Generally, thrust needle roller bearings are known as being composed of a bearing ring, a plurality of needle rollers, and a cage, and can realize high load capacity and high rigidity with a simple structure. Further, since the thrust needle roller bearing has advantages such as a small axial height (thickness), it is widely used for applications that require space saving, such as compressors.

  In the thrust needle roller bearing, differential slip occurs between the roller and the raceway because of its basic structure. More specifically, in the case of a thrust needle roller bearing, a cylindrical needle roller is arranged as a rolling element on a raceway having a flat raceway surface, and the roller and the raceway surface are in line contact. It has become. The center of rotation of the bearing coincides with the center of revolution of the roller. Although the roller has a predetermined length in the radial direction of the bearing, the peripheral speed on the rolling surface of the roller is the same speed. On the other hand, the circumferential speed of the raceway surface of the race which is in rolling contact with the roller increases from the center of rotation of the bearing toward the outer diameter direction. Therefore, the peripheral speed difference between the roller and the raceway surface of 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 peripheral speed difference between the roller and the raceway surface increases from the point on the pitch circle toward both ends of the roller, and differential slip increases. . This differential slip increases in proportion to the length of the roller.

  The differential sliding in thrust needle roller bearings is large compared to other types of bearings. Therefore, due to differential slip, edge stress is likely to occur between the roller edge and the bearing ring, and surface-origin separation is likely to occur at the edge of the roller rolling part of the bearing ring. .

  As a measure for alleviating the effect of differential slip between the roller and the raceway surface of the raceway, it is conceivable to shorten the length of the roller. However, if the length of the roller is simply shortened, the contact area of the roller becomes small, so that the contact surface pressure of the roller increases and there is a possibility that problems such as early peeling occur on the outer surface of the roller.

  As a means for improving the above problem, a double-row thrust needle roller bearing has been proposed. In the case of this bearing, by arranging a plurality of rollers in the radial direction of the bearing while shortening the length of the rollers, the contact surface pressure acting on the rollers can be kept low while alleviating the effect of differential sliding. it can.

  Double row thrust needle roller bearings are disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-97562 (Patent Document 1), Japanese Patent Application Laid-Open No. 2003-156050 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2004-36849 (Patent Document 3). It is disclosed.

  In the double-row thrust needle roller bearing disclosed in Japanese Patent Laid-Open No. 2003-97562 (Patent Document 1), the differential sliding generated on the rolling element surface is reduced, and the load capacity is lowered and the rolling contact surface pressure is increased. In order to suppress this, crowning is formed on the rolling surface of at least one of the plurality of roller rows.

In the double-row thrust needle roller bearing disclosed in Japanese Patent Laid-Open No. 2003-156050 (Patent Document 2), differential sliding is reduced, increase in rolling contact surface pressure is suppressed, and wear of the raceway ring is reduced. In order to have excellent surface damage resistance, a roller with a crowning and a carbide having a particle size of 0.6 μm or more to a depth of at least 0.1 mm of the surface layer are 10,000 / mm ² or more and 40000 / mm per single area. ^{And a} bearing ring having less than ^two .

In the double-row thrust needle roller bearing disclosed in Japanese Patent Laid-Open No. 2004-36849 (Patent Document 3), the oil permeability of the lubricating oil is improved, and the drilling wear of the cage and the differential sliding of the needle roller are reduced. In order to suppress and increase the strength and durability, the end face of the roller is an F end face, and the end face accuracy of the roller is 30 μm or less.
JP 2003-97562 A JP 2003-156050 A JP 2004-36849 A

  In recent years, compressors for automobile air conditioners, automatic transmissions, electric brakes, and the like have been reduced in size and output. Along with this, the usage environment tends to increase in load and temperature, such as lowering the viscosity of the lubricating oil. For bearings, the lubrication environment is changing to be more severe than ever.

  When the lubrication conditions are severe, peeling due to rolling fatigue (peeling starting from the inside) is not performed, and peeling starting from the surface layer (surface) occurs. Unlike radial bearings, thrust bearings rotate with slipping, so oil films are easy to break. Recently, in order to cope with fuel saving, the lubricating oil has been lowered in viscosity, the lubrication conditions for the bearings have become more severe, and the oil film is more likely to be cut.

  Since thrust needle roller bearings have large slip and low oil film forming ability, it is often observed that the bearing life is shortened by surface-origin separation. On the other hand, in double-row thrust needle roller bearings, the double row of rollers reduces slippage and extends the life of the bearing. Is required.

  An object of the present invention is to provide a double-row thrust needle roller bearing capable of obtaining a long life even under severe lubrication conditions.

  The present invention is a double-row thrust needle roller bearing in which a plurality of carbonitrided rollers are arranged in the radial direction of the bearing. According to this configuration, in a double row needle roller bearing that suppresses differential sliding and extends the service life, it is possible to extend the service life even under more severe lubrication conditions by using a carbonitrided roller. Can be realized.

  In one embodiment, the double-row thrust needle roller bearing includes a retainer that holds an outer roller positioned on the radially outer side and an inner roller positioned on the radially inner side. The retainer includes a plurality of pockets provided at intervals in the circumferential direction. The outer roller and the inner roller are accommodated in each of a plurality of pockets.

  In another embodiment, the double-row thrust needle roller bearing includes a cage that holds an outer roller positioned radially outside and an inner roller positioned radially inside, the cage being a bearing. Including a plurality of outer pockets spaced in the circumferential direction at radially outer positions and a plurality of inner pockets spaced in the circumferential direction at positions radially inward of the bearing. . Outer rollers are accommodated in each of the plurality of outer pockets, and inner rollers are accommodated in each of the plurality of inner pockets.

  Preferably, the amount of retained austenite in the surface layer portion of the roller having a depth of 0.05 mm or less from the surface is in the range of 15% to 35%. By making the amount of retained austenite within this range, it is possible to improve the rolling fatigue life against foreign matters in the lubricating oil.

  1 to 3 each show an embodiment of a double-row thrust needle roller bearing according to the present invention. Moreover, FIGS. 4-6 has each shown the arrangement | positioning form of a different roller. In these drawings, the same reference numerals indicate the same or corresponding elements. Further, in these drawings, the bearing race of the bearing is not shown.

  First, the basic structure of a double row thrust needle roller bearing will be described with reference to FIG. The double-row thrust needle roller bearing includes a fixed-side bearing ring (not shown), a rotating-side bearing ring (not shown), and a plurality of rollers 2, which are disposed between both the bearing rings and held by the cage 1. 3. A plurality of rollers 2 and 3 are arranged in the radial direction of the bearing. The roller 2 is disposed inside as viewed in the radial direction, and the roller 3 is disposed outside as viewed in the radial direction. Therefore, in the following description, they are called the inner roller 2 and the outer roller 3.

  There are basically three types of arrangements of the inner roller 2 and the outer roller 3 as shown in FIGS.

  The cage 1 shown in FIG. 4 includes a plurality of pockets 11 provided at intervals in the circumferential direction, and an inner roller 2 and an outer roller 3 are disposed in each pocket 11.

  The cage 1 shown in FIG. 5 has a plurality of outer pockets 12 provided at intervals in the circumferential direction at positions outside the bearing in the radial direction, and a gap in the circumferential direction at positions inside the bearing in the radial direction. A plurality of inner pockets 13, the outer rollers 3 are accommodated in each of the plurality of outer pockets 12, and the inner rollers 2 are accommodated in each of the plurality of inner pockets 13. In the form shown in FIG. 5, the number of inner rollers 2 and the number of outer rollers 3 are the same.

  As in the cage shown in FIG. 5, the cage 1 shown in FIG. 6 has a plurality of outer pockets 12 provided at intervals in the circumferential direction at positions outside the radial direction of the bearing, and the radial direction of the bearing. A plurality of inner pockets 13 that are spaced apart in the circumferential direction at the inner position of each of the plurality of outer pockets. The outer rollers 3 are accommodated in each of the plurality of outer pockets 12, and the inner rollers 2 are accommodated in each of the plurality of inner pockets 13. Is housed. In the form shown in FIG. 6, the number of the inner rollers 2 and the number of the outer rollers 3 are different. Specifically, in the illustrated form, the number of outer rollers 3 is greater than that of inner rollers 2.

  4 to 6, two rollers are arranged in the radial direction, but three or more rollers may be arranged in the radial direction.

  In each embodiment shown in FIGS. 1 to 3, the only difference is the form of the cage 1. In the embodiment shown in FIGS. 1 and 3, the cage 1 is composed of a plate-like first member 1 a and a second member 1 b that are joined one above the other. In the case of the cage 1 shown in FIG. 1, the outer peripheral portion of the first member 1a is bent and clamped to the outer peripheral portion of the second member 1b, and the inner peripheral portion of the second member 1b is bent and the first member 1a is bent. It is clamped and clamped to the inner periphery of the.

  In the case of the cage 1 shown in FIG. 3, the outer peripheral portion and the inner peripheral portion of the ring-shaped first member 1a are bent toward the second member 1b side, and the outer peripheral portion and the inner peripheral portion of the second member 1b are bent to the first member. It is bent toward the 1a side. The bent outer peripheral portion and the inner peripheral portion of the first member 1a are fitted into the bent outer peripheral portion and the inner peripheral portion of the second member 1b.

  The cage 1 shown in FIG. 2 is a single part made of, for example, resin.

  The common point in each embodiment is that the outer roller 3 positioned on the outer side in the radial direction and the inner roller 2 positioned on the inner side in the radial direction are both subjected to carbonitriding. By subjecting the inner and outer rollers to carbonitriding, the thrust needle roller bearing can have a long life even under severe lubrication conditions.

  The carbonitriding process for the rollers is performed as follows. That is, after the roller is kept at a temperature of 840 ° C. for a certain period of time and subjected to carbonitriding, quenching is performed from that temperature, and tempering is further performed at 230 ° C.

  Austenite remains in the surface layer portion of the roller subjected to the carbonitriding process with nitrogen enrichment, and this retained austenite improves the fatigue life. Preferably, the amount of retained austenite in the surface layer portion of the roller having a depth of 0.05 mm or less from the surface is in the range of 15% to 35%. As the amount of retained austenite increases, the rolling fatigue life is improved under the lubrication conditions under the presence of foreign matter. On the other hand, when the amount is too much, the surface hardness decreases and the wear resistance decreases. Considering these points, a preferable amount of retained austenite is in the range of 15% to 35%.

  In order to confirm the effect of the carbonitriding process on the rollers in the thrust needle roller bearings, the present inventor conducted life tests on various thrust needle roller bearings. The results are as follows. Moreover, the bearing type obtained the same result in any of FIGS.

[Test conditions]
Load: 4000N
Rotational speed: 8000 r. p. m.
Lubrication: Mission oil, circulating oil supply, natural temperature rise [Test results]

上記の表１において、Ｌ_１０ｈは、基本定格寿命であり、一群の同じ軸受を同一条件で個々に回転させたとき、その９０％（信頼度９０％）が転がり疲れによるフレーキングを生じることなく回転できる実質的な総回転数を意味する。一定回転速度で回転させたときは、その総回転時間で表わす。上記の試験では回転速度が一定であるので、総時間数を比較した。また、本試験での剥離形態は、表面起点型剥離である。

In Table 1 above, L ₁₀ h is the basic rating life, and 90% (reliability 90%) causes flaking due to rolling fatigue when a group of the same bearings are individually rotated under the same conditions. This means the total number of revolutions that can be rotated without any problems. When rotating at a constant rotation speed, the total rotation time is used. Since the rotation speed was constant in the above test, the total number of hours was compared. Moreover, the peeling form in this test is surface origin type peeling.

As can be seen from Table 1, a single row thrust needle roller bearing using a carbonitrided roller when L ₁₀ h of a single row thrust needle roller bearing using a roller that has been quenched is 1 L ₁₀ h is 2. Further, L _{10 h} double row thrust needle roller bearing using the roller was subjected to dip quenching becomes 5, L _{10 h} double row thrust needle roller bearing using a roller subjected to carbonitriding processing 12 Become. From these results, it is recognized that the life of the double row thrust needle roller bearing is significantly improved if the carbonitriding treatment is performed on the rollers.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and changes can be made to the illustrated embodiment within the same range as the present invention or within an equivalent range.

  In addition, the thrust needle roller bearing does not necessarily have a fixed-side bearing ring and a rotating-side bearing ring, and may have a rolling surface directly on the other side of a member to be incorporated.

  The present invention can be advantageously applied particularly to a double-row thrust needle roller bearing used for a compressor for an air conditioner of an automobile, an automatic transmission, an electric brake or the like.

It is sectional drawing which shows one Embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is a top view which shows an example of the arrangement | positioning form of a some roller. It is a top view which shows the other example of the arrangement | positioning form of a some roller. It is a top view which shows the further another example of the arrangement | positioning form of a some roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cage, 1a 1st member, 1b 2nd member, 2 inside roller, 3 outside roller, 11 pocket, 12 outside pocket, 13 inside pocket

Claims (4)

A double-row thrust needle roller bearing, wherein a plurality of carbonitrided rollers are arranged in the radial direction of the bearing. A retainer for holding an outer roller located on the radially outer side and an inner roller located on the radially inner side;
The cage includes a plurality of pockets provided at intervals in the circumferential direction,
The double row thrust needle roller bearing according to claim 1, wherein the outer roller and the inner roller are accommodated in each of the plurality of pockets. A retainer for holding an outer roller located on the radially outer side and an inner roller located on the radially inner side;
The cage includes a plurality of outer pockets spaced circumferentially at positions radially outside the bearing, and a plurality spaced circumferentially at positions radially inside the bearing. Including the inside pocket,
The outer rollers are accommodated in each of the plurality of outer pockets,
The double row thrust needle roller bearing according to claim 1, wherein the inner roller is accommodated in each of the plurality of inner pockets. The double row thrust needle shape according to any one of claims 1 to 3, wherein the amount of retained austenite in the surface layer portion of the roller having a depth from the surface of 0.05 mm or less is in the range of 15% to 35%. Roller bearing.

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