JP2008002539A - Thrust roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thrust roller bearing capable of effectively suppressing wear at the contact portions between rollers and a retainer. <P>SOLUTION: This thrust roller bearing 11 comprises rollers 11 having, on its end surfaces, curved surfaces swelled in the rolling axial direction, pockets 17 extending, in the thickness direction, through a disk having a hole 14 at its center and containing rollers 12, and a retainer 13 containing an outer peripheral flange part 18 axially extending along the outer periphery of the disk on the outer side of the wall surface 17d on the radial outer side of the pockets 17. The outer peripheral flange part 18 has a guide surface 18a for guiding the end surfaces of the rollers along the wall surface on the radial inner side of the pockets. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thrust roller bearing, and more particularly to a thrust roller bearing used in a car air conditioner compressor, an automatic transmission, a manual transmission, a hybrid vehicle, and the like.

  In recent years, compressors for car air conditioners, automatic transmissions, manual transmissions, hybrid vehicles, and the like have been reduced in size and output, and thrust roller bearings incorporated therein are also required to support higher speeds. On the other hand, the amount of lubricating oil has been reduced and low-viscosity lubricating oil has been used to reduce fuel consumption in consideration of the environment, and the use conditions of thrust roller bearings have been severe. For this reason, there is a problem of wear (drilling wear) that occurs at the contact portion between the end face facing the radially outer side of the roller and the pocket wall surface when the bearing rotates.

  Thus, thrust roller bearings used in such an environment are described in, for example, Japanese Patent Application Laid-Open No. 2003-83333 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2004-301195 (Patent Document 2). Referring to FIG. 5, the thrust roller bearing 101 described in each of the above publications holds a plurality of rollers 102, race rings 103 and 104 that sandwich the plurality of rollers in the axial direction, and a plurality of rollers 102. And a cage 105. The cage 105 has a pair of annular portions 105a and 105b and a plurality of pocket portions 105c formed between the annular portions 105a and 105b. The pocket portion 105c extends to the annular portion 105a on the outer diameter side. is doing.

  Moreover, as a manufacturing method of the cage 105 having the above-described configuration, pocket punching is performed on the steel sheet so as to form a pocket portion 105c that holds the rollers. Thereafter, the inner diameter side is bent outward to form the inner diameter side annular portion 105b. Furthermore, the cage 105 in which the pocket portion 105c extends to the annular portion 105a on the outer diameter side can be manufactured by bending the outer diameter side in the opposite direction inside the outer diameter side end portion of the pocket portion 105c. it can.

The thrust roller bearing 101 configured as described above rotates while the end surface facing the radially outer side of the roller 102 is in contact with the radially inner wall surface of the annular portion 105a, so that it contacts the outer diameter side end portion 105d of the pocket portion 105c. The contact area increases compared to the case. As a result, it is described that wear between the roller 102 and the cage 105 can be effectively suppressed even under severe lubrication conditions.
JP 2003-83333 A JP 2004-301195 A

  In the above manufacturing method, since the bending process is performed after the pocket part 105c is formed, the pocket part 105c at the time of the bending process may be deformed. This can cause a rotation failure of the rollers 102 accommodated in the pocket portion 105c.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thrust roller bearing having a shape in which the cage is easily processed and capable of effectively suppressing wear of a contact portion between the roller and the cage.

  A thrust roller bearing according to the present invention is a disc-shaped member having a plurality of rollers having curved surfaces bulging in the rolling axis direction on the end surface and a hole formed in the center, and penetrates in the thickness direction. A plurality of pockets for storing the rollers, and a cage that is located on the radially outer side of the radially outer wall surface of the pocket and includes an outer peripheral flange that extends in the axial direction along the outer periphery of the disk. And an outer periphery collar part has a guide surface which guides the end surface of a roller to the wall surface inside radial direction.

  In the thrust roller bearing configured as described above, the top of the curved surface formed on the end surface of the roller and the guide surface provided on the outer peripheral flange contact when the bearing rotates. Here, the peripheral speed of the end face of the roller is the smallest in the rotation axis of the roller (the center of the roller diameter) and increases toward the outside in the radial direction. Thus, by matching the rotational axis at the top of the curved surface, the PV value of the contact portion between the roller end surface and the cage guide surface can be reduced, and wear of the contact portion can be effectively suppressed. . The “PV value” refers to a value obtained by multiplying the contact surface pressure P (MPa) between the roller end surface and the cage guide surface by the sliding speed V (m / min).

  In addition, the cage having the above-described configuration can be punched in the pocket after the shape of the cage is formed by bending, so that high-precision machining is easy to perform. As a result, a thrust roller bearing with reduced manufacturing costs can be obtained.

  Preferably, when the length of the guide surface in the axial direction is L and the roller diameter of the roller is D, L / D> 0.3 is satisfied. Since the cage is displaced to some extent in the axial direction when the bearing rotates, the relative position of the rollers inside the pocket also changes. Therefore, by setting the axial length L of the guide surface within the above range, the contact state between the roller end surface and the guide surface can be maintained even when the cage is displaced in the axial direction. In addition, even when the roller has a small diameter, it is possible to secure a guide surface for the roller end surface to contact.

  More preferably, the surface roughness Ra of the guide surface satisfies Ra <2 μm. By setting the surface roughness of the guide surface to a predetermined value or less, wear of the roller end surface, the guide surface, and the contact portion can be more effectively suppressed. In the present specification, “surface roughness Ra” is an arithmetic average roughness, which is extracted from the roughness curve by a reference length in the direction of the average line, and the deviation from the average line of the extracted portion to the measurement curve. The absolute values of these are summed and averaged.

  According to the present invention, it is possible to obtain a thrust roller bearing having a shape in which the cage is easily processed and capable of effectively suppressing wear of a contact portion between the roller and the cage.

  With reference to FIG. 1 and FIG. 2, the thrust roller bearing 11 which concerns on one Embodiment of this invention is demonstrated. 1 is a plan view of a thrust roller bearing 11 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.

  The thrust roller bearing 11 is a cage-and-roller type bearing having a plurality of rollers 12 and a retainer 13 that holds the interval between adjacent rollers 12, and mainly includes a compressor for an car air conditioner, an automatic transmission, a manual transmission, And used in hybrid vehicles.

  The roller 12 is a cylindrical roller having a cylindrical rolling surface and end surfaces having curved surfaces bulging in the direction of the rolling axis at both end surfaces. The end face shape is an A end face or an AR end face defined by JIS standards (Japan Industrial Standards: B 1506), and the top of the curved surface formed on the end face coincides with the rotational axis of the roller 12.

  The cage 13 is a disk-shaped member having a hole 14 formed in the center, and is formed by bending a metal flat plate by pressing or the like. And between the inner periphery collar part 15 formed along the outer periphery of the hole 14, the outer periphery collar part 18 formed along the outer periphery of the holder | retainer 13, and the inner periphery collar part 15 and the outer periphery collar part 18, it is a roller. A plurality of pockets 17 for accommodating 12 are formed, and has a roller holding portion 16 extending in the radial direction.

  The inner peripheral flange portion 15 is formed by being bent by a predetermined length toward one side in the thickness direction of the cage 13 and then folded back by 180 °. Further, the wall surface facing the hole 14 of the inner peripheral flange 15 functions as a guide surface 15a that guides the shaft when it is incorporated into the rotating shaft. In the present invention, the inner peripheral flange 15 is not an essential component, but the rigidity of the cage 13 is improved by providing the inner peripheral flange 15.

  The roller holding portion 16 extends in the radial direction while being bent in the thickness direction of the cage 13, and a plurality of pockets 17 penetrating in the thickness direction are arranged radially with respect to the bearing rotation axis with the longitudinal direction directed in the radial direction. Has been.

  The pocket 17 has a rectangular shape along the outer shape of the roller 12, and the wall surface facing the rolling surface of the roller 12 in the pocket 17 is the axial direction of the roller 12 at the radial center of one side in the thickness direction of the cage 13. A first retaining portion 17a for preventing the roller 12 from coming off; a second retaining portion 17b for preventing the roller 12 from coming off to the other side in the axial direction at both ends in the radial direction on the other side in the thickness direction of the cage 13; And an inclined portion 17c for connecting the first and second retaining portions 17a and 17b.

  The first and second retaining portions 17a and 17b protrude from the wall surface on one side in the longitudinal direction of the pocket 17 toward the wall surface on the other side, abut against the rolling surface of the roller 12, and the axial direction of the cage 13 Regulate displacement.

  The outer peripheral flange 18 is positioned further radially outward of the wall 17d on the radially outer side of the pocket 17, and is bent by a predetermined length toward one side in the thickness direction of the cage 13 like the inner peripheral flange 15. , 180 ° folded back. The rigidity of the cage 13 is also improved by providing the outer peripheral flange 18. Further, a guide surface 18 a for guiding the end surface of the roller 12 is formed on the radially inner wall surface of the outer peripheral flange portion 18.

  Next, with reference to FIG. 3 and FIG. 4, the relationship between the end surface of the roller 12 and the guide surface 18a provided in the outer periphery collar part 18 is demonstrated. 3 is an enlarged view of a portion P in FIG. 2 and shows a state in which the end face of the roller 12 and the guide surface 18a are not in contact with each other. FIG. 4 is an enlarged view of the portion P in FIG. It is a figure which shows the state which 12 end surfaces and the guide surface 18a are contacting. In both figures, the upper part shows a plan view and the lower part shows a side sectional view.

  First, referring to FIG. 3, the length of the pocket 17 in the longitudinal direction is slightly longer than the length of the roller 12. Therefore, when the bearing is stopped, the end surface of the roller 12 on the radially outer side and the outer peripheral flange 18. In some cases, the guide surface 18a is not in contact.

  The guide surface 18a indicates a cylindrical portion extending in the direction of the bearing rotation axis excluding bent portions at both ends of the wall surface on the radially inner side of the outer peripheral flange portion 18, and its axial length is L, the roller diameter of the roller 12. Is set so as to satisfy L / D> 0.3.

  The cage 13 serves as a roller guide by providing the pocket 17 with first and second retaining portions 17a, 17b. Therefore, if the axial length L of the guide surface 18a is short, the end surface of the roller 12 may be detached from the guide surface 18a when the cage 13 is biased in the axial direction. Therefore, by setting the axial length L of the guide surface 18a to be longer than the axial displacement amount of the cage 13, the end surface of the roller 12 can always be in contact with the guide surface 18a during the bearing rotation. The amount of axial displacement of the cage 13 can be adjusted by the amount of protrusion of the retaining portions 17a and 17b.

On the other hand, in order to rolling surface of the roller 12 is in contact with both sides in the thickness direction of the raceway surface of the thrust roller bearing 11 is required to be smaller than the thickness L ₀ Gakoro diameter D of the retainer 13. Further, in the cage 13 manufactured by press working, it is difficult to eliminate the bent portions at both ends of the guide surface 18a. Therefore, the axial length L of the guide surface 18a needs to be set within a range satisfying L <L ₀ <D.

  Further, by using the cage 13 as a roller guide, the wall surface in the thickness direction of the cage 13 and the raceway surface are not in contact with each other, so torque loss during rotation of the bearing can be suppressed and the thickness of the cage 13 can be suppressed. Oil permeability between the direction wall surface and the raceway surface is improved. Thereby, it is possible to reduce the amount of heat generated when the bearing rotates.

  Next, referring to FIG. 4, the roller 12 moves radially outward by centrifugal force accompanying the rotation of the thrust roller bearing 11. At this time, the end surface of the roller 12 is in contact with only the guide surface 18 a provided on the outer peripheral flange 18, and is not in contact with the radially outer wall surface 17 d of the pocket 17. Specifically, the top of the curved surface provided on the end surface of the roller 12 comes into contact with the guide surface 18a.

  Here, the peripheral speed of the end face of the roller 12 is the smallest at the rotational axis (the center of the roller diameter) of the roller 12 and increases toward the outside in the radial direction. Therefore, by bringing the top of the curved surface that coincides with the center of the roller diameter into contact with the guide surface 18a, the wear of the contact portion can be effectively suppressed.

  Further, as a method for further effectively suppressing the wear of the contact portion between the end surface of the roller 12 and the guide surface 18a, the surface roughness Ra of the guide surface 18a is set to satisfy Ra <2 μm. Similarly, the surface roughness of the end face of the roller 12 is preferably within the above range.

  Next, a method for manufacturing the cage 13 having the above configuration will be described. The cage 13 is manufactured by pressing using a steel plate such as carbon steel as a starting material. First, a steel plate is punched into a disc shape and a hole 14 is formed in the center. Next, portions that become the inner peripheral flange portion 15, the outer peripheral flange portion 18, and the roller holding portion 16 are formed by bending. Finally, the pocket 17 penetrating in the thickness direction of the cage 13 and the first and second retaining portions 17a and 17b are formed by punching. At this time, the pockets 17 may be processed one by one, but by processing all the pockets 17 at the same time, the processing time can be shortened and the processing accuracy can be improved. Finally, the guide surface 18a is ground to reduce the surface roughness to a predetermined value or less.

  In order to obtain predetermined mechanical properties such as hardness, the cage 13 manufactured by the above method is subjected to heat treatment such as soft nitriding treatment, carburizing quenching, and tempering. In addition, since the processing of the cage 13 described above is performed while supplying lubricating oil to the processed portion, it is desirable to wash and dry the lubricating oil adhering to the surface of the cage 13 before the heat treatment.

  By punching the pocket 17 after the bending of the outer peripheral flange 18 as in the above manufacturing process, the processing accuracy of the pocket 17 is improved. Thereby, the roller 12 accommodated in the pocket 17 can rotate smoothly.

  In the manufacturing method of the cage 13 described above, an example of grinding is shown as a method for reducing the surface roughness of the guide surface 18a to a predetermined value or less. However, the present invention is not limited to this, and other methods may be adopted. Good. For example, barrel processing may be used. Alternatively, the gap between the punch and the die used when forming the outer peripheral flange 18 is reduced by about 2% to 3% from the plate thickness of the cage 13 to perform the ironing process. Simultaneously with the formation, the surface roughness of the guide surface 18a can be within the above range.

  However, in order to perform the processing in the above order, the radially outer wall surface 17d of the pocket 17 needs to be separated from the radially inner wall surface of the outer peripheral flange portion 18 to some extent. Specifically, the protrusion amount δ from the radially inner wall surface of the outer peripheral flange portion 18 of the radially outer wall surface 17d of the pocket 17 needs to be about 20 μm to 40 μm. Therefore, the roller diameter of the roller 12, the radius of curvature of the end surface, and the axial direction of the cage 13 are set so that the end surface of the roller 12 and the radially outer wall surface of the pocket 17 do not come into contact with each other even when the protrusion amount δ is within this range. It is necessary to set the amount of displacement.

  By adopting the above-described configuration, it is possible to suppress wear at the contact portion between the roller 12 and the guide surface 18a, and to reduce the amount of heat generated when the bearing rotates, so that a compressor for an car air conditioner, an automatic transmission, a manual transmission, a hybrid vehicle, etc. The thrust roller bearing 11 having excellent durability and high reliability can be obtained in the high-speed and lean lubrication environment.

  In the above-described embodiment, the roller 12 is shown as an example in which curved surfaces bulging in the direction of the rolling axis are formed on both end faces. However, in order to obtain the effects of the present invention, the roller 12 faces at least radially outward. It is sufficient to form a curved surface only on the end face.

  Further, in the above embodiment, an example is shown in which the top of the curved surface formed on the end face of the roller 12 coincides with the rotational axis 12 of the curved surface, but the top of the curved surface has a relatively small peripheral speed near the rotational axis. If it is located at a place, the effect of the present invention can be obtained even if the two do not exactly match.

  Moreover, in said embodiment, after the inner periphery collar part 15 and the outer periphery collar part 18 were bent predetermined length toward the thickness direction one side of the holder | retainer 13, the example folded back 180 degrees was shown. However, the present invention is not limited to this, and any shape that improves the rigidity of the cage 13 can be used.

  In the above embodiment, an example in which the cage 13 is a roller guide has been described. However, the present invention is not limited to this, and a cage for track surface guidance may be used.

  Further, the thrust roller bearing 11 in the above embodiment is an example of a cage and roller type bearing composed of the roller 12 and the cage 13, but is not limited thereto, and the track covers one or both of the axial directions. A ring may be further provided.

  Furthermore, although the example which employ | adopted the cylindrical roller as the rolling element showed the thrust roller bearing 11 in said embodiment, this invention is applicable not only to this but a thrust needle roller bearing. Since the thrust needle roller bearing has a small thickness direction dimension, it is effective in reducing the axial dimension of the support portion.

  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 variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The present invention is advantageously used in thrust roller bearings that support shafts of compressors for car air conditioners, automatic transmissions, manual transmissions, and hybrid vehicles.

It is a top view of the thrust roller bearing which concerns on one Embodiment of this invention. It is sectional drawing in II-II of FIG. FIG. 3 is an enlarged view of a portion P in FIG. 2, showing a state where the roller and the guide surface are not in contact with each other. FIG. 3 is an enlarged view of a portion P in FIG. 2, showing a state where a roller and a guide surface are in contact with each other. It is a figure which shows the conventional thrust roller bearing.

Explanation of symbols

11, 101 Thrust roller bearing, 12, 102 roller, 13, 105 cage, 105a, 105b annular part, 105c pocket part, 105d outer diameter side end part, 103, 103 race ring, 14 holes, 15 inner peripheral flange part, 15a guide surface, 16 roller holding portion, 17 pocket, 17a, 17b retaining portion, 17c inclined portion, 17d wall surface, 18 outer peripheral flange portion, 18a guide surface.

Claims (3)

A plurality of rollers having curved surfaces bulging in the direction of the rolling axis on the end surface;
A disk-shaped member having a hole formed in the center, the plurality of pockets penetrating in the thickness direction to accommodate the rollers, and located on the radially outer side of the radially outer wall surface of the pocket, the circle A cage including an outer peripheral flange extending in the axial direction along the outer periphery of the plate;
The outer peripheral flange is a thrust roller bearing having a guide surface that guides an end face of the roller on a radially inner wall surface. When the axial length of the guide surface is L and the roller diameter of the roller is D,
L / D> 0.3
The thrust roller bearing according to claim 1, wherein: The surface roughness Ra of the guide surface is
Ra <2 μm
The thrust roller bearing according to claim 1 or 2, wherein

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