JP5621352B2 - Thrust roller bearing - Google Patents

Description

  The present invention relates to an improvement in a thrust roller bearing which is mounted on a rotating part of an electrical component such as an automobile transmission (manual and automatic), a transfer, or a car cooler compressor and supports a thrust load applied to the rotating part. . Specifically, by reducing the rotational resistance (dynamic torque) acting during operation, the performance of various mechanical devices incorporating thrust roller bearings is improved. The thrust roller bearing that is the subject of the present invention is not limited to one that uses a general roller having a large diameter (thickness) with respect to the axial dimension (length) as each roller that is a rolling element, Also included are so-called needle bearings that use needles with a small diameter relative to the axial dimension.

  Thrust roller bearings are widely used to support the thrust load applied to the rotating parts of transmissions and compressors for car coolers. First, a first example of the conventional structure of such a thrust roller bearing will be described with reference to FIG. The thrust roller bearing includes a plurality of rollers 1, a pair of races 2 a and 2 b, and a cage 3. Each of these rollers 1 is arranged in a radial direction. The races 2a and 2b are each formed in an annular shape from a metal plate, and are arranged concentrically with each other. The surfaces facing each other are used as raceway surfaces 4a and 4b for rolling contact with the rolling surfaces of the rollers 1. In the illustrated example, flange portions 5a and 5b are formed that are bent at substantially right angles from the outer peripheral edge or the inner peripheral edge of the races 2a and 2b toward the opposite races 2b and 2a. The cage 3 is composed of a combination of first and second cage elements 6 and 7. Each of the cage elements 6 and 7 is formed by bending a metal plate, and has a U-shaped cross section and is formed into an annular shape as a whole. Both of these cage elements 6 and 7 are fitted and combined in a state in which the phases of the rectangular through holes 8 and 8 formed in the radial direction are matched with each other, and the portions where these through holes 8 and 8 are formed are A pocket 9 is provided for holding the rollers 1 in a rollable manner.

  Each of the rollers 1, the races 2a, 2b, and the retainer 3 each having the shape as described above are arranged in a pocket 9 of the retainer 3 as shown in FIG. The rollers 1 are held together and the rollers 1 are combined in a sandwiched state between the races 2a and 2b arranged concentrically with each other. In this state, the races 2a and 2b can be rotated relative to each other. Therefore, for example, if one race 2a is attached to a fixed part such as a casing and the other race 2b is attached to a rotating member such as a gear, the thrust member that adds the rotating member to the rotating member with respect to the fixed part is provided. It can be supported rotatably while supporting the load.

The basic configuration of the thrust roller bearing is as described above, but the thrust roller bearing is provided between the rolling surface of each roller 1 and the raceway surfaces 4a and 4b of both races 2a and 2b. A differential slip occurs, and it is inevitable that the rotational resistance (dynamic torque) increases based on the differential slip. On the other hand, due to the recent trend of resource saving, etc., it is required to reduce the rotational resistance of the rotation support part of various mechanical devices, and the thrust resistance of the thrust roller bearing is also required to be reduced. ing. There are various factors that increase the rotational resistance of thrust roller bearings, but the major factors include the following factors (1) to (3).
(1) Friction based on differential slip between the rolling surface of each roller and a pair of raceway surfaces in rolling contact with the rolling surface.
(2) With respect to the radial direction of both the raceway surfaces, friction between the axial outer end surfaces of the rollers and the inner surfaces of pockets holding the rollers so as to roll freely.
(3) Friction acting between the cage that holds the rollers and the mating surface.

  Among the factors (1) to (3) described above, in order to reduce the friction based on the factor (1), the rolling contact surface of each roller, the raceway surface, and the surface pressure of the rolling contact portion are changed to the respective rolling force. It is conceivable that the height is higher in the axial center of the surface (on the pitch circle and in the vicinity thereof) and lower toward both ends. Such a surface pressure distribution is such that there is no differential slip, or even if it is small, both axial ends of each rolling surface where the differential slip is larger than the surface pressure at the axial center of each rolling surface. This means that the surface pressure of the part is lowered, so that friction based on the factor (1) can be reduced. Further, as a structure capable of realizing such a surface pressure distribution, for example, as described in Patent Documents 1 to 3, the cross-sectional shape of each raceway surface is a convex circle in which the radial intermediate portion swells toward each roller. It can be considered to have an arc shape.

  10A and 10B show two examples of the conventional structure described in Patent Document 1 among them. In the case of these two conventional structures, the raceway surfaces 4a ′, 4b ′, 4a ″, 4b ″ are obtained by curving the intermediate portions in the width direction (radial direction) of the races 2a ′, 2b ′, 2a ″, 2b ″. The cross-sectional shape is a convex arc shape. Although not shown, Patent Document 2 discloses that the cross-sectional shape of each raceway surface is a convex arc shape by making the thickness of the intermediate portion in the width direction (radial direction) of each race larger than the thickness of both end portions. Is described. By adopting such a structure, the surface pressure at both axial ends can be made lower than the surface pressure at the axially central portion of each rolling surface.

Alternatively, as described in Patent Documents 4 to 5, it is conceivable to crown the rolling surfaces of each roller. In other words, as shown in FIG. 11, the generatrix of the rolling surface 10 of the roller 1a is a convex arc, and the outer diameter of the roller 1a is large at the center in the axial direction and gradually decreases toward both ends in the axial direction. I have to. Even with such a structure, the surface pressure at both axial ends can be made lower than the surface pressure at the axial center of each rolling surface.
The structures described in Patent Documents 1 to 5 described above are intended to improve the surface pressure distribution of the rolling contact portion and to improve the rolling fatigue life of each rolling surface and raceway surface. By properly regulating the radius of curvature of the convex arc shape and the amount of falling crowning, the friction based on the factor (1) can be reduced by the mechanism as described above.

  In order to reduce the friction based on the factor (2), it is conceivable that the axial end surface of each roller is a convex surface in which the central portion in the radial direction of each roller protrudes in the axial direction. That is, the friction based on the factor (2) is caused by the centrifugal force based on the revolving motion of each roller. This is caused by rubbing against each other in a state of being pressed against the inner surface of the radially outer end portion in each of the pockets that hold the surface. This rubbing may be based on the rotational motion of each roller or based on a revolving motion. By making the end surfaces in the axial direction of these rollers convex, it is possible to reduce the friction radius based on the rotation of these rollers and reduce the friction based on the factor (2). As a structure capable of reducing the friction in this way, as shown in Patent Documents 1 and 6, a structure in which the axial end surface of each roller is a partially spherical convex surface is known.

  Further, in order to reduce friction based on the factor (3), the positioning in the axial direction of the cage is based on the engagement between the circumferential side edges of each pocket and the rolling surface of each roller. A guide structure can be considered. As an aspect in which the friction based on the factor (3) is increased, one side of the cage in the axial direction and one of the raceway surfaces rub against each other through an oil film, and the holding is performed based on a large shear resistance acting on the oil film. It can be considered that resistance against the rotation of the vessel increases. On the other hand, as described in, for example, Patent Documents 6 and 7, if the positioning of the cage in the axial direction is achieved by the roller guide structure, the friction based on the factor (3) can be reduced.

  As described above, the structures of the inventions described in Patent Documents 1 to 7 all suppress the increase in rotational resistance of the thrust roller bearing based on any one of the above (1) to (3). It is done. However, this is not a structure that can reduce all of the factors (1) to (3), and this rotational resistance cannot be reduced sufficiently. In addition, considering only the fact that the factors (1) to (3) are eliminated and the rotational resistance of the thrust roller bearing is reduced, the structures of the inventions described in Patent Documents 1 to 7 may be combined. If the posture of each roller becomes unstable (the rotation shaft is easily displaced from the radial direction of the cage), the rotational resistance of the thrust roller bearing may increase. That is, in order to reduce the rotational resistance based on the factor (1), when the cross-sectional shape of the raceway surface is a convex arc shape and the axial end surface of each roller is a partial spherical convex surface, The posture of the roller becomes unstable, and the rotational resistance of the thrust roller bearing cannot always be reduced.

Japanese Patent Laid-Open No. 7-119740 JP 2007-16810 A JP 2007-170447 A JP 2001-65574 A JP 2007-327596 A JP 2008-240750 A JP 2004-156738 A

  In view of the circumstances as described above, the present invention reduces the friction based on all the factors such as (1) to (3) described above without causing the posture of each roller to be unstable. The invention was invented to realize a roller bearing structure in which the resistance can be stably kept low.

The thrust roller bearing of the present invention includes a plurality of rollers, at least one race, and a cage, like the conventionally known thrust roller bearing.
Each of these rollers is arranged in a radial direction.
The race is formed of a hard metal plate having a thickness T, such as a bearing steel plate or a case-hardened steel plate, and has a raceway surface that makes the rolling contact surfaces of these rollers contact each other.
The retainer has a ring-shaped main portion and a plurality of pockets that are radially formed in a radially intermediate portion of the main portion and hold the rollers in a freely rolling manner. .

In particular, in the thrust roller bearing of the present invention, the metal plate constituting the race has a thickness T of 0.5 to 1.5 mm.
Further, an intermediate portion of the raceway raceway surface in the radial direction of the race has a convex cross section projecting toward the rolling surface of each of the rollers, which can be elastically deformed by applying a thrust load . In this case, the cross-sectional shape of the intermediate portion is, for example, a convex arc shape whose central portion protrudes toward the rolling surface of each roller.
Further, assuming that the protrusion height of the convex section of the cross section, which is the intermediate portion, of the raceway surface of the race is H, the protrusion height H is set in the range where the thickness T is 0.5 to 1 mm. When the thickness T is in the range of 1 to 1.5 mm, the protruding height H is 5 to 30 μm.
Further, in the roller guide structure, positioning of the cage in the axial direction is achieved based on engagement between both circumferential edges of the pockets and rolling surfaces of the rollers.
Further, of the axial end surfaces of the rollers, the central portion in the radial direction of the rollers is a flat surface that exists in a direction perpendicular to the central axis of the rollers, and the outer portion in the radial direction is also the same. The inclined surface is inclined in the direction toward the axial center of each roller as it goes outward in the diameter direction.
The diameter of the flat surface is preferably 20 to 80% of the diameter of each roller as in the invention described in claim 2. This value is more preferably 40 to 75%, and most preferably 50 to 70%.

  When carrying out the thrust roller bearing of the present invention configured as described above, for example, as in the invention described in claim 3, the retainer is first and second holding each formed by bending a metal plate. A combination holder is formed by combining container elements. In this case, each of the first and second cage elements has both inner and outer peripheral edges of an annular flat plate portion in which a plurality of rectangular through holes for forming pockets are formed in the circumferential direction with respect to the axial direction. It is assumed that both the inner diameter side and outer diameter side cylindrical portions are formed by bending the same side. The flat plate portions of the first and second cage elements are arranged opposite to each other with respect to the axial direction, and the phases in the circumferential direction of the through holes formed in both the flat plate portions are matched. Then, the inner diameter side cylindrical portion of the first cage element is externally fitted to the inner diameter side cylindrical portion of the second cage element. At the same time, the outer diameter side cylindrical portion of the first cage element is fitted into the outer diameter side cylindrical portion of the second cage element. Further, the width of each through hole in the circumferential direction of each cage element is made smaller than the outer diameter of each roller. Then, based on the engagement between both circumferential edges of each through hole and the rolling surface of each roller, positioning in the axial direction of the cage with respect to each roller is achieved.

  Or like the invention described in Claim 4, the said retainer shall be produced by bending and forming the cross-sectional shape regarding radial direction in the crank shape of one metal plate. Specifically, the retainer is arranged near the one end portion in the axial direction of the retainer, on the inner side flat plate portion disposed in the portion near the other end in the axial direction, and near one end in the axial direction. It is assumed that each pocket is formed so as to extend from the inner diameter side flat plate portion to the outer diameter side flat plate portion. Of the circumferential edges of each pocket, the retainer is attached to each of the rollers based on the engagement between the portions corresponding to both the inner diameter side and outer diameter side flat plate portions and the rolling surfaces of the rollers. On the other hand, the cage is prevented from displacing to the other end side in the axial direction, and based on the engagement between the portion corresponding to the intermediate flat plate portion and the rolling surface of these rollers, the cage is By preventing displacement to one end side in the direction, positioning in the axial direction of the cage with respect to each of these rollers is achieved.

According to the thrust roller bearing of the present invention configured as described above, friction based on the factors (1) to (3) described above can be reduced, and the rotational resistance can be stably kept low.
First, since the cross-sectional shape of the radial intermediate portion of the raceway surface of the race is a convex shape such as a convex arc shape, the differential slip at the rolling contact portion between this raceway surface and the rolling surface of each roller is large. Thus, the surface pressure at both end portions in the axial direction of these rollers can be kept low. For this reason, an increase in rotational resistance based on this differential slip can be suppressed.

  However, in order to suppress an increase in rotational resistance due to the differential slip, if the surface pressure of the rolling contact portion is high at the central portion in the axial direction and low at both end portions in the axial direction, the postures of the rollers are not changed as they are. It becomes unstable, and the direction of the central axis of each roller and the diameter direction of the cage are likely to be shifted. In other words, the circumferential direction of the cage, which coincides with the revolution direction of each roller, and the direction in which each roller tries to roll (direction perpendicular to the central axis of each roller) are likely to be shifted. And when it shift | deviates, according to the magnitude | size of the shift | offset | difference, the slip which generate | occur | produces in the said rolling contact part becomes large, and the said rotational resistance becomes large. On the other hand, in the case of the present invention, among the axial end faces of the rollers, the central portion in the radial direction of the rollers is a flat surface that exists in a direction orthogonal to the central axis of the rollers. Therefore, the engagement between the flat surface and the inner surface of the pocket prevents the center axis of each roller from deviating from the diametrical direction of the cage, and the slip that occurs at the rolling contact portion based on this deviation. Can be suppressed. Even in this case, since the radially outward portion of the axial end surfaces of the rollers is an inclined surface, the friction between the axial end surfaces of the rollers and the inner surfaces of the pockets based on the rotation of the rollers. The turning radius of the mating portion can be kept small, and the frictional resistance at the rubbing portion can be suppressed.

Further, in the case of the present invention, since the positioning of the cage in the axial direction is achieved by a roller guide structure, both the axial side surfaces of the cage and the rolling surfaces of the rollers are in rolling contact with each other. A pair of raceway surfaces can be sufficiently separated. For this reason, between these two raceway surfaces facing each other and both axial side surfaces of the cage, the rotational resistance of the cage is increased on either side (between the surfaces facing each other). Oil film is not formed. For this reason, the dynamic torque of the thrust roller bearing can also be reduced by reducing the rotational resistance of the cage.
Moreover, in the case of the thrust roller bearing of the present invention, the dynamic torque can be reduced without reducing the load capacity by appropriately combining the above-described constituent elements. In other words, when the dynamic torque is the same, the load capacity can be increased.

The partial cutaway perspective view (A) which omits only one race which shows the 1st example of an embodiment of the invention, and shows a partial section view (B) which omits both races, one race and holding Partially cut perspective view (C) showing the container omitted. Partial sectional drawing (A)-(D) which shows five examples of the cross-sectional shape of a race, and the diagram (E) which shows the bus-line of a track surface. (A) is a partial side view showing a shape belonging to the present invention and (B) and (C) are shapes deviating from the present invention with respect to the end face shape of the roller. The figure similar to FIG. 1 which shows the structure of the comparative example which remove | deviates from the technical scope of this invention. Sectional drawing (A) which shows the 2nd example of embodiment of this invention in the state which took out the roller and the holder, and the perspective view (B) which expands and shows the P section of (A). The diagram which shows the result in case an axial load is 500 N among the experiments conducted in order to know the influence which the presence or absence of the convex curve part of the raceway surface has on the dynamic torque of a thrust roller bearing. The diagram which similarly shows the result in the case of 1000N. Sectional drawing which shows another 3 examples of the shape of the race which can be used for implementation of this invention. The fragmentary sectional view which shows the 1st example of the roller bearing conventionally known by the state (A) before an assembly, and the state (B) after an assembly. The fragmentary sectional view which shows the 2nd-3rd example. The side view which shows an example of the roller which gave crowning.

[First example of embodiment]
A first example of an embodiment of the present invention corresponding to claims 1, 2, and 4 will be described with reference to FIGS. The thrust roller bearing of this example includes a plurality of rollers 1b and 1b, a pair of races 2A, and one cage 3a. In the drawing, in order to clearly show these rollers 1b and 1b and the cage 3a, only one race 2A of a pair of races is drawn, and the other race is omitted.

  The rollers 1b and 1b are arranged in a radial direction along a raceway surface 4A formed on one side of the race 2A. That is, the central axes of the rollers 1b and 1b are arranged in the radial direction of the race 2A. In the case of this example, as these rollers 1b and 1b, those in which the respective rolling surfaces 10 are crowned are used. Note that the crowning of the rolling surface 10 of each of the rollers 1b and 1b is exaggerated (with a smaller radius of curvature than the actual case) for clarity. When practicing the present invention, the crowning of the rolling surface 10 is not essential and can be omitted. Further, in the case of the thrust roller bearing of the present example, flat surfaces 11 and 11 are formed at the center portions in the radial direction of the rollers 1b and 1b among the axial end surfaces of the rollers 1b and 1b, respectively. ing. The directions of the flat surfaces 11 and 11 are directions orthogonal to the central axes of the rollers 1b and 1b.

Further, as shown in FIG. 3 (A), the axial direction of each of the rollers 1b and 1b is increased toward the outer side in the radial direction, as shown in FIG. An inclined surface 12 is formed that is inclined in a direction toward the center. Note that the inclination angle of the inclined surface 12 with respect to the direction of the central axis of each of the rollers 1b and 1b is greater than the inclination angle of the inclined surface 12a formed as a general chamfer as shown in FIG. Is also large (close to 90 degrees). With this configuration, the width dimension W12 in the radial direction of the inclined surface ₁₂ can be secured without increasing the axial dimension L of the inclined surface 12, and the diameter d of the flat surface 11 can be made an appropriate dimension. ing. That is, the diameter d of the flat surface 11 is set to 20 to 80% {d = (0.2 to 0.8) D} of the diameter D of the rollers 1b and 1b.

Further, both the races 2A are formed in an annular shape with an L-shaped cross section by subjecting a hard metal plate, which will be described later, to processing such as punching and bending with a press. Of these, one side of the ring portion 13 is used as the raceway surface 4A, and a cylindrical flange portion 5b is formed on the inner peripheral edge. In the raceway surface 4A, an intermediate portion in the radial direction of the race 2A is a convex curved surface portion 14 that is continuous over the entire circumference of the raceway surface 4A. With this configuration, in the state where no load (thrust load) is applied to the thrust roller bearing of this example, the raceway surface 4A and the rolling surface 10 of each of the rollers 1b and 1b are intermediate in the axial direction of the rolling surface 10. It is made to contact | abut only by a part, and it is made not to contact | abut at both ends of an axial direction. In a state where a load is applied, the raceway surface 4A and the rolling surfaces 10 of the rollers 1b and 1b are in rolling contact over the entire axial length of the rolling surface 10 , but the contact portion is not touched. The contact pressure is high at the intermediate portion in the axial direction of the rolling surface 10 and low at both end portions in the axial direction.

  The cross-sectional shape of the race 2A including the convex curved surface portion 14 is restricted in design according to the usage pattern, but for example, shapes as shown in FIGS. 2A to 2E can be adopted. Of these, the cross-sectional shape shown in (A) increases the width W of the convex curved surface portion 14 by making the radius of curvature relatively large (close to the length of the rollers 1b and 1b in the axial direction). In addition, the convex curved surface portion 14 is installed in the central portion in the width direction (radial direction) of the annular ring portion 13. On the other hand, the cross-sectional shape shown in (B) makes the width dimension w of the convex curved surface portion 14 smaller by making the radius of curvature relatively small (than the length dimension in the axial direction of the rollers 1b and 1b). Is also sufficiently short) and the installation position is biased radially outward of the annular ring portion 13. In the case of FIG. 2B, the installation position of the convex curved surface portion 14 is biased in this way, and the outer diameter side of the annular portion 13 that is present in the outer portion with respect to the radial direction than the convex curved surface portion 14. The width dimension a of the plane portion 15 is made smaller (a <b) than the width dimension b of the inner diameter side plane portion 16 that also exists in the inner portion.

  By adopting the cross-sectional shape shown in (B) above, even when the convex curved surface portion 14 having a small width dimension w is employed, when the thrust roller bearing supports the thrust load, the convex curved surface portion 14 It is crushed smoothly. The reason for this is as follows. When the thrust roller bearing supports a thrust load, the convex curved surface portion 14 is crushed, and as a result, the width dimension of the convex curved surface portion 14 in the radial direction increases. In this way, when the width dimension of the convex curved surface portion 14 is expanded, the outer diameter of the outer diameter side plane portion 15 is increased, or the inner diameter of the inner diameter side plane portion 16 is reduced, so that the extension of the width dimension is increased. Need to absorb. According to the cross-sectional shape shown in (B), the width dimension a of the outer-diameter side plane portion 15 is reduced, and the outer diameter of the outer-diameter side plane portion 15 is easily increased. Is crushed smoothly.

  Unlike the cross-sectional shape shown in the above (B), even if the convex curved surface portion 14 is biased radially inward of the annular ring portion 13 and the width dimension of the inner diameter side flat surface portion 16 is reduced, this annular ring portion is reduced. Due to the presence of the flange portion 5b at the inner peripheral edge portion 13, the resistance against the reduction of the inner diameter of the inner diameter side plane portion 16 cannot be made sufficiently small. Accordingly, when the flange portion 5a is present on the outer diameter side as in the above-described upper race 2a in FIG. 9, the convex curved surface portion 14 is biased radially inward of the annular portion 13, and the inner diameter side plane portion. It is preferable to reduce the width dimension of 16. In any case, both the outer diameter side and inner diameter side flat surface portions 15 and 16 exist on any surface (for example, a fixed portion such as a casing or a part of a rotating member such as a gear) that backs up the race 2A. When the thrust load is supported, the elastic deformation of the convex curved surface portion 14 is performed smoothly.

  As described above, when the thrust roller bearing applies a thrust load and the convex curved surface portion 14 is crushed, of the inner and outer peripheral edges of the annular portion 13, The diameter increases or decreases. At this time, if a portion of this edge that rubs against any of the surfaces backing up the race 2A is sharp, the portion bites into this surface (causes this surface to be caught or galling), There is a possibility that the resistance against the crushing of the convex curved surface portion 14 is increased. Therefore, in order to prevent an increase in resistance due to such a cause, as shown in FIGS. 2C and 2D, a portion of the edge that rubs against one of the surfaces should be a convex curved surface. Is preferred. Of these, the structure shown in (C) is a curved surface 17a formed by curving the entire outer peripheral edge of the annular ring portion 13 in a direction away from any of the surfaces, and the structure shown in (D) is A convex curved surface 17b is formed at a portion of the outer peripheral edge portion of the annular ring portion 13 that opposes any one of the surfaces.

  Regardless of the structure, when the convex curved surface portion 14 is crushed and its width dimension is expanded, the edge is prevented from biting into any of the surfaces, and the convex curved surface portion 14 is crushed. It is possible to stably keep the resistance against being low. In addition, the presence of the convex curved surfaces 17a and 17b makes it easy for lubricating oil to enter the rubbing portion between the ring portion 13 and the one of the surfaces, and along with the expansion and contraction of the width of the convex curved portion 14, It is possible to suppress the occurrence of damage such as fretting wear in the rubbing portion. Similarly, convex curved surfaces 17c and 17d are also formed on the continuous portion between the width direction (radial direction) both ends of the concave curved surface existing on the opposite side of the convex curved surface portion 14 and the flat surface portion, It is preferable to prevent any of the surfaces from rubbing strongly, or to make the lubricating oil easily enter the rubbing portion. The convex curved surface 17a shown in (C) is formed by plastic deformation of a part of the race 2A. The convex curved surfaces 17b to 17d shown in (C) and (D) are not only plastic working but also barrels. It can also be formed by processing or shot processing.

Moreover, as shown in FIGS. 2A to 2C, the cross-sectional shape of the convex curved surface portion 14 formed in the race 2A may be a single arc whose curvature radius does not change in the middle, or (D). As shown, it may be a composite arc in which a plurality of arcs having different curvature radii are smoothly connected. In the case of a compound arc, the radius of curvature of the radially outer portion is preferably increased, and the radius of curvature of the inner portion is also decreased. This is because the rollers 10 and 10 are displaced radially outward by centrifugal force during the operation of the thrust roller bearing and are in rolling contact with the radially outward portion of the convex curved surface portion 14. This is because increasing the radius of curvature of the portion is advantageous in terms of stabilizing the posture of the rollers 10 and 10.
Further, as the cross-sectional shape of the convex curved surface portion 14, a sinusoidal curve shape, a parabolic shape, a normal distribution shape, or the like can be adopted. One example of the sinusoidal curve shape is shown in FIG. The sinusoidal curve shape is expressed by, for example, y = K · sin θ. Furthermore, a logarithmic crowning shape as described in Patent Document 4 can also be used.
The formation of the convex curved surfaces 17b to 17d in the portion facing any one of the surfaces is the same regardless of the difference in the cross-sectional shape of the convex curved surface portion 14.

  Further, the position of the convex curved surface portion 14 with respect to the radial direction of the race 2A is appropriately restricted in relation to the positions of the rollers 1b and 1b held in the pockets 9a and 9a of the cage 3a. Specifically, the center of the convex curved surface portion 14 with respect to the radial direction of the race 2A is set to a substantially central position in the length direction of the rollers 1b and 1b. In other words, the diameter at the center in the width direction of the convex curved surface portion 14 and the pitch circle diameter (PCD) of each of the rollers 1b and 1b are substantially the same. However, the radial direction position of the convex curved surface portion 14 depends on the cross-sectional shape of the convex curved surface portion 14 and the generatrix shape of the rolling surface 10 of each of the rollers 1b and 1b (whether or not crowning exists). It is set as appropriate according to the state of use (whether or not the entire cylindrical roller bearing revolves).

  In any case, the thickness dimension T of the metal plate constituting the race 2A and the height H of the convex curved surface portion 14 are determined by design according to specifications such as the dimensions of the thrust roller bearing and the load capacity. For example, the thickness dimension T is in the range of 0.1 to 3 mm. The thrust roller bearing of this example is used in a state where the race 2A is brought into contact with any one of a pair of surfaces facing each other in the thrust direction and backed up by the surface. Therefore, as long as the rigidity of this surface is sufficiently high, it is difficult to cause a problem even if the thickness dimension is small from the surface that supports the thrust load. However, in the case of the thrust roller bearing of this example, when the thrust load is applied, the convex curved surface portion 14 is elastically deformed as described above (high in the intermediate portion in the axial direction and low in both end portions in the axial direction). Realize surface pressure distribution. When realizing such a surface pressure distribution, the convex curved surface portion 14 is appropriately elastically deformed over the entire axial length of the rolling contact portion so that an uneven load or an excessive load is not applied (biased). It is necessary to absorb the load and prevent an excessive load from being applied partially). In consideration of such points, when the thickness dimension T is 0.1 mm or less, the ability to absorb the uneven load becomes poor (the convex curved surface portion 14 is deformed even with a very small uneven load), It is not possible to prevent an excessive surface pressure from being partially applied based on the uneven load. On the other hand, if the thickness dimension T exceeds 3 mm, it becomes difficult to elastically deform based on the thrust load, and not only is this difficult to absorb when an offset load is applied, but an excessive thrust load is added. In such a case, there is a possibility that damage such as cracking may occur.

  Further, the material of the hard metal plate constituting the race 2A is preferably bearing steel such as SUJ2, SK steel such as SK5, carburized steel, etc., and generally, after these are processed into a predetermined shape, heat treatment is performed. Use one cured by The surface hardness of the race 2A manufactured under such conditions generally exceeds Hv600. In the case of the race 2A having such a high hardness, if the plate thickness increases, it becomes difficult to elastically deform the convex curved surface portion 14 in the crushing direction. Depending on the material of the hard metal plate, as described above, the thickness dimension T can be selected in the range of 0.1 to 3 mm. However, the hard metal plate is made of bearing steel such as SUJ2 or SK steel such as SK5. In the case of (carbon tool steel) or carburized steel, the thickness dimension is preferably regulated to a range of 0.5 to 2 mm, more preferably 0.7 to 1 mm.

Further, the height H of the convex curved surface portion 14 is appropriately determined in consideration of various use conditions including the magnitude of the thrust load (load capacity) applied when the thrust roller bearing is used and the thickness dimension T. . Generally, it is preferable to regulate the height H to a range of about 1 to 100 μm. When the height H is less than 1 μm, the effect of reducing the friction of the differential slip by adjusting the surface pressure distribution based on the elastic deformation of the convex curved surface portion 14 is hardly obtained. On the other hand, when the height H exceeds 100 μm, the convex curved surface portion 14 is not sufficiently crushed in a normal use state, and the area of the rolling contact portion between the rollers 1b and 1b and the raceway surface 4A. Cannot be secured sufficiently, and the surface pressure of the rolling contact portion becomes excessive, and it becomes difficult to secure the rolling fatigue life of the rolling surface 10 of each of the rollers 1b and 1b and the raceway surface 4A. Therefore, the height H is restricted to a range of about 1 to 100 μm, preferably 5 to 50 μm, more preferably 5 to 40 μm. More specifically, it is preferable to regulate as follows in relation to the thickness T.
When the thickness T is 0.5 to 1 mm: the height H is 5 to 40 μm
When thickness T is 1 to 1.5 mm: Height H is 5 to 30 μm
When thickness T is 2 mm or more: Height H is 5 to 20 μm
That is, as the thickness T is increased, the convex curved surface portion 14 is less likely to be crushed, so that the maximum value of the height H is kept small as described above. The convex curved surface portion 14 is sufficiently crushed to secure a contact area of the rolling contact portion between the convex curved surface portion 14 and the rolling surface 10 of each of the rollers 1b and 1b. Prevents contact surface pressure from becoming excessive and ensures the durability of thrust roller bearings.

  In addition, the height H of the convex curved surface portion 14 can be regulated by a ratio to the thickness T of the metal plate constituting the race 2A. For example, although partially overlapping with the above-described range, when the thickness T is, for example, about 0.8 mm (0.7 to 1 mm), the height H is set to 1/200 of the thickness T. It is preferable to set to 1/20 (4-40 micrometers). More preferably, the height H is restricted to a range of 1/200 to 1/50 (4 to 16 μm) of the thickness T. If this height H is regulated within this range, when a thrust load is applied to the thrust roller bearing, the convex curved surface portion 14 is appropriately elastically deformed so that the thrust load is offset or excessively large. Also in this case, in addition to the effect of suppressing the partial increase in the surface pressure of the rolling contact portion, an additional effect such as reducing the impact load becomes remarkable, which is preferable.

  Furthermore, in order to obtain these effects, the width dimension W in the radial direction of the convex curved surface portion 14 is appropriately regulated. Specifically, the width W is preferably 100 times or more (W ≧ 100H) of the height H, and more preferably 200 times or more (W ≧ 200H). However, the width W is 70% or less {W ≦ 0.7 (a + w + b)} of the width of the annular portion 13 (a + w + b in FIG. 2B).

The preferable specifications related to the race 2A described above are summarized as follows.
First, the material is most preferably SK material (carbon tool steel of JIS G 4401).
The thickness dimension T is most preferably limited to a range of 0.7 to 1 mm.
The height H is most preferably regulated to a range of 1/200 to 1/50 (3.5 to 20 μm) of the thickness T.
Furthermore, it is most preferable that the width W is regulated to 200 times or more (0.7 mm or more) of the height H and 70% or less of the width of the annular portion 13.

  Next, the cage 3a is integrally formed by bending a metal plate such as a steel plate or a stainless steel plate into a crank shape with a cross-sectional shape in the radial direction. Specifically, the cage 3a includes, in order from the inner diameter side to the outer diameter side, a guide cylindrical portion 18, a guide ring portion 19, an inner diameter side cylindrical portion 20, an inner diameter side flat plate portion 21, The inner diameter side step part 22, the intermediate | middle flat plate part 23, the outer diameter side step part 24, the outer diameter side flat plate part 25, and the outer diameter side cylindrical part 26 are provided. Of these, the inner diameter of the guide cylindrical portion 18 is slightly larger than the outer diameter of the flange portion 5b formed on the inner peripheral edge of the race 2A, and the guide cylindrical portion 18 can be rotated on the flange portion 5b. It can be fitted externally. In the case of this example, in the cage 3a, the main body part for holding the rollers 1b and 1b in a rollable manner is the inner diameter side cylindrical portion 20 and the inner diameter side flat plate of the respective portions 18 to 26. The portion 21, the inner diameter side step portion 22, the intermediate flat plate portion 23, the outer diameter side step portion 24, the outer diameter side flat plate portion 25, and the outer diameter side cylindrical portion 26 are configured. The guide ring portion 19 has a function of arranging the main body portion of such a cage 2A around the flange portion 5b and concentrically with the flange portion 5b.

  The main body portion of the retainer 2A has an outer peripheral edge of the inner diameter side flat plate portion 21 disposed at a portion closer to one axial end (the upper end in FIG. 1) of the retainer 2A, and the other axial end (the lower end in FIG. 1). ) Both the inner and outer peripheral edges of the intermediate flat plate portion 23 arranged at the near portion and the inner peripheral edge of the outer diameter side flat plate portion 25 also arranged at the portion near the one end in the axial direction are both the inner diameter side and the outer diameter side. The step portions 22 and 24 are made continuous, and the inner diameter side cylindrical portion 20 is continued from the inner peripheral edge of the inner diameter side flat plate portion 21, and the outer diameter side cylindrical portion 26 is continued from the outer peripheral edge of the outer diameter side flat plate portion 25. Let me. The pockets 9a and 9a are respectively formed between the cylindrical portions 20 and 26 on the inner diameter side and the outer diameter side in a state of punching the flat plate portions 21, 23 and 25 and the stepped portions 22 and 24, respectively. , Provided radially.

Engagement protrusions 27a, 27b, 27c are formed at both end edges in the circumferential direction of the flat plate portions 21, 23, 25 so as to protrude into the pockets 9a, 9a, respectively. The intervals between the tips of the locking protrusions 27a, 27b, 27c, which are arranged in a state of being opposed to each other in the circumferential ends of each of the pockets 9a, 9a, are the same among the rollers 1b, 1b. It is slightly smaller than the outer diameter of the portion aligned with the locking protrusions 27a, 27b, 27c. When the rollers 1b, 1b are held in the pockets 9a, 9a, the rollers are elastically expanded with the gaps between the tips of the locking projections 27a, 27b, 27c paired with each other. 1b and 1b are pushed into the pockets 9a and 9a. In a state where the pushing is completed, the retainer 2A is engaged with the rollers 1b based on the engagement between the tip edge portions of the locking protrusions 27a, 27b, 27c and the rolling surfaces of the rollers 1b, 1b. 1 to suppress displacement in the axial direction. In other words, with the rollers 1b and 1b held in the pockets 9a and 9a so as to freely roll, the roller 2b and 1b are positioned in the axial direction of the retainer 2A with a so-called roller guide structure. Plan.
Further, the flat surface 11 formed at the center of the axial end surface of each of the rollers 1b and 1b in the state where the rollers 1b and 1b are held in the pockets 9a and 9a as described above, It faces the inner peripheral surface of the radial cylindrical portion 26.

According to the thrust roller bearing of the present example configured as described above, for the reasons described above, the friction acting on the contact portion between the surface of each of the rollers 1b and 1b and the mating surface is reduced, and the rotational resistance is reduced. Stable and low.
First, the convex curved surface portion 14 is formed at the radial intermediate portion of the raceway surface 4A of the race 2A, and the rolling surfaces of the rollers 1b and 1b are crowned, so that rotational resistance based on differential slip The increase of can be suppressed. That is, of the rolling contact portion between the raceway surface 4A and the rolling surface 10 of each of the rollers 1b and 1b, a portion that deviates radially from the pitch circle of each of the rollers 1b and 1b (the outer diameter of the raceway surface 4A). In the near part and the part near the inner diameter = the part near the both ends in the axial direction of the rolling surface 10), there is a difference between the peripheral speed and the revolution speed of the rolling surface 10 with respect to each of the rollers 1b and 1b. Slip (the differential slip) occurs. On the other hand, according to the structure of this example, the surface pressure at both end portions in the axial direction of the rollers 1b and 1b, where the differential slip increases, is suppressed based on the presence of the convex curved surface portion 14 and the crowning. It is done. The increase in rotational resistance based on the differential slip can be suppressed by the amount that the surface pressure can be lowered.

  In order to reduce the rotational resistance based on differential slip as described above, it is not always necessary to crown the rolling surfaces of the rollers 1b and 1b. Even if the convex curved surface portion 14 is only formed in the radial direction intermediate portion of the raceway surface 4A of the race 2A, a general rolling surface having a simple cylindrical shape may be used as each of the rollers 1b and 1b. good. In any case, according to the structure of this example, in addition to suppressing an increase in rotational resistance due to the differential slip, the thrust roller bearing receives an eccentric load, etc., so that the centers of the rollers 1b and 1b Even when the shaft and the reference surface of the race 2A (outer diameter side and inner diameter side flat surface portions 15 and 16) are not parallel, the convex curved surface portion 14 is elastically deformed as the rolling surface 10 is displaced. In addition, it is possible to prevent the occurrence of edge load due to the contact between the axial end edge of the rolling surface 10 and the raceway surface 4A. In addition, it is possible to prevent the rolling surface 10 and the raceway surface 4A from being damaged such as early separation, thereby improving the life of the thrust roller bearing.

  As described above, regardless of the shape of the rollers 1b and 1b, by providing the convex curved surface portion 14, the rotational resistance based on the differential slip can be suppressed, and the life of the thrust roller bearing can be extended. As it is, the postures of the rollers 1b and 1b become unstable. That is, if the surface pressure of the rolling contact portion is high at the axial center portion of the rolling surface 10 and low at both axial end portions, the postures of the rollers 1b and 1b become unstable as they are. The direction of the central axis of each roller 1b, 1b and the diameter direction of the cage 2A are likely to be displaced. In other words, the circumferential direction of the cage 2A, which coincides with the revolution direction of the rollers 1b and 1b, and the direction in which the rollers 1b and 1b try to roll easily deviate. And when it shift | deviates, according to the magnitude | size of the shift | offset | difference, the slip which generate | occur | produces in the said rolling contact part becomes large, and the said rotational resistance becomes large.

  On the other hand, in the case of the thrust roller bearing of this example, the flat surface 11 is formed at the center of the axial end surface of each of the rollers 1b and 1b, and this flat surface 11 is used during the operation of the thrust roller bearing. It is made to engage with the inner peripheral surface of the outer diameter side cylindrical portion 26 of the cage 3a. That is, during operation of the thrust roller bearing of this example, the rollers 1b and 1b are displaced radially outward of the cage 3a within the pockets 9a and 9a due to centrifugal force based on revolving motion, The flat surface 11 abuts on the inner peripheral surface of the outer diameter side cylindrical portion 26. Since the diameter d of the flat surface 11 is 20% or more of the diameter D of each of the rollers 1b and 1b, the engagement between the flat surface 11 and the inner peripheral surface of the outer diameter side cylindrical portion 26 Contact) prevents the center axis of each of the rollers 1b and 1b from deviating from the diameter direction of the cage 3a, and prevents slippage occurring at the rolling contact portion based on this deviation. On the other hand, since the diameter d of the flat surface 11 is suppressed to 80% or less of the diameters of the rollers 1b and 1b, the axial end surfaces of the rollers 1b and 1b are based on the rotation of the rollers 1b and 1b. The rotational radius of the rubbing portion with the inner peripheral surface of the outer diameter side cylindrical portion 26 can be suppressed to be small, and the frictional resistance at the rubbing portion can be suppressed.

  In order to obtain the effect obtained by forming the flat surface 11 as described above, the diameter d of the flat surface 11 is restricted to a range of 20 to 80% of the diameter D of the rollers 1b and 1b. There is a need to. When this value is less than 20%, the postures of the rollers 1b and 1b are likely to be unstable, and the frictional resistance based on the deviation between the rotation direction and the revolution direction of the rollers 1b and 1b is likely to increase. . For example, in the case of a structure in which the axial end face is a partially spherical convex surface as shown in FIG. 3B in contrast to the structure of this example as shown in FIG. It becomes unstable. On the other hand, when the value exceeds 80%, friction between the flat surface 11 and the inner peripheral surface of the outer diameter side cylindrical portion 26 increases, and the effect of reducing the dynamic torque of the thrust roller bearing can be sufficiently achieved. Disappear. For example, as shown in FIG. 3C, in the case of a structure in which the diameter of the flat surface of the axial end surface is increased, the friction between the axial end surface and the mating surface due to the rotation of the roller increases, The torque cannot be reduced sufficiently. Considering these points, the diameter d of the flat surface 11 is restricted to a range of 20 to 80% of the diameter D of the rollers 1b and 1b. More preferably, this value is 40 to 75%, Preferably, it is regulated within a range of 50 to 70%.

Further, the effect of reducing the frictional resistance by appropriately regulating the diameter d of the flat surface 11 can be obtained notably from the surface of reducing the dynamic torque of the thrust roller bearing during high speed operation. Although effective even at low speeds, ensuring the stability of the rollers during high-speed operation where the product (dmn value) of the roller pitch circle diameter and the thrust roller bearing rotation speed (min ^-1 ) exceeds 400,000 And the effect of forming an oil film at the sliding contact portion (the oil film is easily formed because the rollers are stable, and the oil film is easily formed at a high speed). In order to effectively perform the oil film formation, the portion where the rolling surface 10 and the flat surface 11 of the roller 1b are continuous is inclined with respect to the central axis of the roller 1b as described above. The inclined surface 12 has a large angle or is chamfered with a large curvature radius (an inclined surface having a convex curved surface). Preferably, the chamfer has a large radius of curvature, the axial length of the chamfered portion is made as short as possible to ensure the effective length of the rolling surface 10 of the roller 1b, and the flat surface 11 extends from the rolling surface 10 to the flat surface 11. Suppresses the occurrence of burrs and burrs in the area up to. If such an inclined surface 12 or chamfer is formed and the effective length of the rolling surface 10 is ensured, the rated load of the thrust roller bearing does not decrease, and the durability of the thrust roller bearing decreases. There is nothing.

  Further, in the case of the thrust roller bearing of this example, the positioning of the cage 3a in the axial direction is achieved by a roller guide structure. That is, the front end edges of the locking projections 27a, 27b, 27c that protrude into the pockets from both circumferential edges of the pockets 9a, 9a and the rolling surfaces 10, 10 of the rollers 1b, 1b, By this engagement, the retainer 3a is prevented from being displaced in the axial direction of the retainer 3a with respect to the rollers 1b and 1b. Therefore, as can be seen from FIGS. 1A and 1B, both the axial side surfaces of the cage 3a and a pair of raceway surfaces 4A with which the rolling surfaces of the rollers 1b and 1b come into rolling contact are provided. Can be separated sufficiently. For this reason, between these two raceway surfaces 4A facing each other and both axial side surfaces of the cage 3a, the rotational resistance of the cage 3a is increased on either side (surfaces facing each other). No oil film is formed between them. Further, even in a situation where the amount of lubricating oil is small and such an oil film is not formed, the friction between the both raceway surfaces 4A and both side surfaces in the axial direction of the cage 3a is prevented, and the rotation of the cage 3a is prevented. Increase in resistance can be suppressed.

That is, as shown in FIG. 4, as in the structure of a comparative example that deviates from the technical scope of the present invention, the structure to be achieved by the engagement (contact) between one axial surface of the cage 3b and the raceway surface 4B of the race 2B. In this case, an oil film is formed between one axial surface of the cage 3b and the raceway surface 4B of the race 2B, and this oil film becomes a resistance to relative rotation between the cage 3b and the race 2B. Alternatively, the resistance increases as the two surfaces rub against each other directly. On the other hand, in the case of this example, such an oil film is formed or the two surfaces are prevented from directly rubbing to reduce the rotational resistance of the cage 3a, and the dynamic torque of the thrust roller bearing can be reduced. Reduction can be achieved. In order to obtain this effect with certainty, the thickness t in the axial direction of the cage 3a is 55 to 85% of the diameter D of the rollers 1b and 1b {t = (0.55 to 0.85). D} is preferable. More preferably, it is 65 to 85% {t = (0.65 to 0.85) D}.
As described above, in the case of the thrust roller bearing of this example, the dynamic torque can be reduced without reducing the load capacity by appropriately combining the above-described constituent elements. In other words, when the dynamic torque is the same, the load capacity can be increased.

[Second Example of Embodiment]
FIG. 5 shows a second example of an embodiment of the present invention corresponding to claims 1 to 3. In the case of this example, a combination of the first and second cage elements 6a and 7a is used as the cage 3c. The basic structure of the cage 3c is the same as that of the cage 3 having the conventional structure shown in FIGS. In particular, in the case of the thrust roller bearing of this example, the positioning of the cage 3c in the axial direction is achieved by roller guides as in the case of the first example of the above-described embodiment, and the shaft of the cage 3c. A sufficient gap is formed between the both side surfaces in the direction and the mating surface so as not to form an oil film enough to increase the rotational resistance. Further, in the case of the structure of this example, the rollers 1c and 1c are used in which the rolling surface 10 has a simple cylindrical shape. Since the structure and operation of the other parts are the same as in the case of the first example of the embodiment described above, illustration and description regarding the equivalent parts are omitted.

  An experiment conducted for confirming the effect of the present invention will be described. First, an experiment conducted in order to know the influence of the presence or absence of the convex curved surface portion (center convex) on the raceway surface of the race on the dynamic torque of the thrust roller bearing will be described with reference to FIGS. Of these FIGS. 6 to 7, FIG. 6 shows a case where the thrust load is 500 N, and FIG. 7 shows a case where the thrust load is 1000 N. As shown in FIGS. 6 to 7, when a convex curved surface portion is not provided on any of the pair of raceway surfaces that are in rolling contact with the rolling surface of each roller (both are not convex in the middle), the drive side (rotation) When the convex curved surface is provided only on the raceway surface (side), and when the convex curved surface is provided only on the driven side (spinning side), the middle side is only convex. The dynamic torque of the thrust roller bearing was measured for each of the cases in which convex curved surface portions were provided on both raceway surfaces (both had middle convexity). The supply amount of the lubricating oil was changed to two stages of 1000 ml / min and 500 ml / min, and the thrust load was changed to two stages of 500 N and 1000 N, respectively. The type of lubricating oil was automatic fluid (ATF), and the oil temperature was 80 ° C. As can be seen from FIGS. 6 to 7 showing the results of such an experiment, the dynamic torque of the thrust roller bearing is the lowest when the convex curved surface portions are provided on both of the pair of raceway surfaces, and then only on the swirling side. When provided, the dynamic torque is the lowest in the order in which only the rotation side is provided, and the maximum dynamic torque is obtained when no convex curved surface portion is provided on any of the raceway surfaces.

Next, know the effect of the combination of the convex curved surface of the raceway surface, the flat surface at the center of the end surface in the axial direction of the roller, and the positioning of the cage by the roller on the torque reduction of the thrust roller bearing. I will explain the experiments I did.
The experimental conditions are as follows.
Bearing size (inner diameter x outer diameter x roller diameter): 22 x 38 x 2.5 (unit: mm)
Race ring material: SK5
Race thickness: 0.8mm
Rotational speed: 5000min ^-1
Thrust load: 500N
Lubricating oil: Automatic fluid (ATF)
Oil temperature: 100 ° C
Height of convex curved surface part: 10 μm
Diameter of the flat surface at the center of the roller end face: 1.5 mm
Thickness in the axial direction of the cage: 1.8mm
The above are the conditions regarding Examples 1 and 2, and the cage of Example 1 has the structure shown in FIG. 5, and the cage of Example 2 has the structure shown in FIG.
Further, as Comparative Example 1, a convex curved surface portion is provided on the raceway surface, but the end surface of each roller is a partial spherical convex curved surface as shown in FIG. Further, as Comparative Example 2, a cage having the structure shown in FIG. 5 is used as a bearing ring guide, and as Comparative Example 3, a cage having the structure shown in FIG. 4, the structure shown in FIG. 1 is provided with a convex curved surface portion on the raceway surface, and the cage is positioned as a roller guide, but the roller end surface is a partially spherical convex curved surface. did. Other conditions are the same as those in the first and second embodiments.

And about each of these Examples 1 and 2 and Comparative Examples 1-4, the dynamic torque under the driving | running condition mentioned above was measured. The value of the dynamic torque is set to 1000 in Comparative Example 1, and is shown below in comparison with the value.
Example 1: 749
Example 2: 793
Comparative Example 1: 1000
Comparative Example 2: 946
Comparative Example 3: 952
Comparative Example 4: 971
As is clear from the results of the experiment described above, by combining all the elements of the convex curved surface portion of the raceway surface, the flat surface of the central portion of the axial end surface of the roller, and the positioning of the cage by the roller, With regard to the thrust roller bearing, it is possible to obtain an effect more than the sum of the individual effects of these elements.

  When the present invention is carried out, a flat race having no flange portion as shown in FIG. 10B can be used. In this case, it is necessary to identify the assembly direction of the race. In this case, if a race having convex curved surface portions formed on both sides as described in Patent Document 2 is used, a convex curved surface is provided on the raceway surface with a structure that does not require identification of the assembly direction. Accompanied effects can be obtained. Further, as can be seen from the experimental results of Example 1 described above, the convex curved surface portion is preferably formed on both of the pair of races. However, the convex curved surface is formed only on one side of the race depending on the limitation of the peripheral structure. Even if the portion is provided, a certain degree of effect can be obtained. However, in that case, it is preferable that the race provided with the convex curved surface portion is a race on the side where the stop or rotation speed is low.

  In addition, as a race used when the present invention is implemented, a convex curved surface portion 14 having a single convex arc shape is formed on the annular portion 13 as shown in FIGS. 2 (A) to (D). Not only what was done, but what formed the convex curve part 14 of the shape shown to (A)-(C) of Drawing 8 is also employable. Of these, the race 2C shown in (A) is a double concentric convex curved surface portion 14, and the race 2D shown in (B) is a triangular shape with rounded corners (curved). A lace 2E shown in FIG. 2C is formed by forming a trapezoidal convex curved surface portion 14 with rounded corners (curved surfaces). Even when the races 2C to 2E having any shape are adopted, the friction based on the factors (1) to (3) described above is reduced, and the rotational resistance can be stably kept low. When the race 2C shown in FIG. 8A is adopted, in order to reduce the friction based on the differential slip shown in the above-mentioned (1), the convex portion on the inner diameter side and the outer diameter side are used. It is preferable to shorten the distance from the convex portion.

1, 1a, 1b, 1c roller 2a, 2b, 2a ′, 2b ′, 2a ″, 2b ″, 2A, 2B, 2C, 2D, 2E
Race 3, 3a, 3b, 3c Cage 4a, 4b, 4a ', 4b', 4a ", 4b", 4A, 4B Track surface 5a, 5b Flange part 6, 6a First cage element 7, 6b Second Retainer element 8, 8a Through-hole 9, 9a, 9b Pocket 10 Rolling surface 11 Flat surface 12, 12a Inclined surface 13 Annular portion 14 Convex surface portion 15 Outer diameter side plane portion 16 Inner diameter side plane portion 17, 17a, 17b, 17c Convex surface 18 Guide cylindrical portion 19 Guide annular portion 20 Inner diameter side cylindrical portion 21 Inner diameter side flat plate portion 22 Inner diameter side step portion 23 Intermediate flat plate portion 24 Outer diameter side step portion 25 Outer diameter side flat plate portion 26 Outer diameter side cylinder 27a, 27b, 27c Locking protrusion

Claims (4)

A plurality of rollers arranged in a radial direction;
At least one race having a raceway surface that is formed into an annular shape from a metal plate having a thickness T and that makes the rolling contact surfaces of these rollers contact each other;
Thrust provided with an annular main portion and a cage formed in a radial direction at a radially intermediate portion of the main portion and having a plurality of pockets inside each of the rollers so as to be capable of rolling. In roller bearings,
The thickness T of the metal plate constituting the race is 0.5 to 1.5 mm,
Of raceway surface of the race, an intermediate portion in the radial direction of the race, which elastically deformable by loading the thrust load, a convex section which protrudes said to the raceway side of the rollers,
Of the raceway surface of the race, when the projecting height of the convex portion of the cross section that is the intermediate portion is H,
When the thickness T is in the range of 0.5 to 1 mm, the protruding height H is 5 to 40 μm,
In the range where the thickness T is 1 to 1.5 mm, the protruding height H is 5 to 30 μm,
The roller guide structure in which positioning in the axial direction of the cage is achieved based on engagement between both circumferential edges of the pockets and rolling surfaces of the rollers,
Of the axial end faces of the rollers, the central portion in the radial direction of the rollers is a flat surface that exists in a direction orthogonal to the central axis of the rollers, and the outer portion in the radial direction is the diameter. A thrust roller bearing, wherein the thrust roller bearing is an inclined surface that is inclined in a direction toward an axial center portion of each of the rollers toward the outer side in the direction.   The thrust roller bearing according to claim 1, wherein a diameter of a flat surface existing at a central portion of an axial end surface of each roller is 20 to 80% of a diameter of each roller.   The cage is a combination cage formed by combining first and second cage elements each formed by bending a metal plate, and each of the first and second cage elements is used to form a pocket. The inner and outer peripheral edge portions of the annular flat plate portion having rectangular through holes formed at a plurality of locations in the circumferential direction are bent to the same side in the axial direction to form both the inner diameter side and outer diameter side cylindrical portions. The retainer has the flat plate portions of the first and second retainer elements arranged on opposite sides with respect to the axial direction, and a phase in the circumferential direction of the through holes formed in both the flat plate portions. With the inner diameter side cylindrical portion of the first retainer element fitted on the inner diameter side cylindrical portion of the second retainer element, and the outer diameter side cylinder of the first retainer element. Part is fitted into the outer cylindrical part of the second cage element. The width of each through hole in the circumferential direction of each cage element is smaller than the outer diameter of each roller, and the engagement between both circumferential edges of each through hole and the rolling surface of each roller The thrust roller bearing according to any one of claims 1 to 2, wherein positioning in the axial direction of the cage with respect to each of the rollers is achieved.   The cage is made by bending a single metal plate into a crank shape with a cross-sectional shape in the radial direction, and an inner diameter side flat plate portion disposed near one end in the axial direction of the cage. An intermediate flat plate portion disposed at a portion near the other end in the direction and an outer diameter side flat plate portion disposed at a portion near the one end in the axial direction, and each pocket from the inner diameter side flat plate portion to the outer diameter side flat plate portion. Of the two circumferential edges of each pocket in the circumferential direction, based on the engagement between the portions corresponding to both the inner diameter side and outer diameter side flat plate portions and the rolling surface of each roller, The cage is prevented from displacing to the other end in the axial direction with respect to each of the rollers, and the cage is also based on the engagement between the portion corresponding to the intermediate flat plate portion and the rolling surface of each of the rollers. By preventing displacement of these rollers toward one end in the axial direction Thereby achieving the positioning in the axial direction of the cage with respect to each of these rollers, a thrust roller bearing according to any one of claims 1-2.

Images