JP2006336720A - Bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing unit capable of suppressing the lowering of the preload of a bearing due to thermal expansion and the lowering of smoothness of rotation and durability due to the lowering of the preload and capable of suppressing an increase in the size of a retainer. <P>SOLUTION: A C-ring 25 formed of a material with a coefficient of linear expansion higher than that of differential carriers 16a and 16b is installed between the outer peripheral surface 17d of the outer race 17a of a tapered roller bearing 17 and the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b supporting the outer race 17a on the outer peripheral surface 17d. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing unit including a bearing and a retainer that supports the race.

  With regard to such a bearing unit, for example, Patent Document 1 describes one that is employed in a differential device for an automobile. The outer race of the bearing is supported by the differential carrier as a retainer, and the inner race rotatably supports the drive shaft.

In general, in such a bearing, the preload is appropriately adjusted, so that the smoothness of rotation in the bearing and the durability thereof can be maintained at a high level.
JP-A-7-280069

  By the way, when the temperature of such a bearing unit rises, the bearing and the retainer are deformed by thermal expansion. When the surface pressure between the bearing and the retainer is reduced due to this deformation, the preload of the bearing is thereby lowered, and there is a concern that smooth rotation of the bearing is impaired or its durability is lowered. In the configuration described in Patent Document 1, in order to suppress such thermal expansion of the retainer, heat radiating fins are formed to protrude from the retainer. Therefore, in this configuration, there arises a disadvantage that the retainer is increased in size by the protrusion of the radiating fin.

  The present invention has been made in view of such circumstances, and its purpose is to suppress a decrease in bearing preload due to thermal expansion and a decrease in rotational smoothness and durability associated therewith and to increase the size of the retainer. It is providing the bearing unit which can be suppressed.

In the following, means for achieving the above object and its effects are described.
First, the invention according to claim 1 is a bearing unit including a radial bearing including an outer race and an inner race, and a retainer that supports the outer race, and supports the outer race on the outer peripheral surface of the outer race and the outer peripheral surface. The gist is that an interposition member made of a material having a higher linear expansion coefficient than the retainer is provided between the retainer and the support surface.

  According to this configuration, since the interposed member is formed of a material having a higher linear expansion coefficient than the retainer, the amount of thermal expansion (expansion length) when the temperature rises to the same temperature is larger in the interposed member than in the retainer. Become. Therefore, when such a temperature rise occurs, a decrease in the pressing force received on the outer peripheral surface of the outer race from the support surface side of the retainer is suppressed by the thermal expansion of the interposed member. As a result, a decrease in preload, a decrease in smoothness of rotation, and a decrease in durability of the radial bearing are suppressed. Further, for example, as compared with the conventional mode in which the heat radiating fins are formed so as to suppress the thermal expansion of the retainer, it is possible to easily suppress the increase in size of the retainer.

  Here, the above-mentioned “thermal expansion amount” refers to the thermal expansion amount per unit length of each member. Therefore, if the “thermal expansion amount” is compared, for example, it will be compared how much the portions of the retainer and the intervening member that have the same length before thermal expansion have expanded.

The gist of the invention described in claim 2 is that, in the invention described in claim 1, the retainer is formed of a material having a higher linear expansion coefficient than the outer race.
In such a configuration, the phenomenon that the pressing force received by the outer peripheral surface of the outer race from the support surface side of the retainer decreases as the temperature of these members rises becomes more prominent. In that respect, according to the present invention, such a decrease in the pressing force is suitably suppressed by the thermal expansion of the interposition member.

  In addition, about such an interposition member, you may make this provide in multiple in the specific part between the outer peripheral surface of an outer race, and the support surface of a retainer, For example, according to invention of Claim 3, an interposition member is provided. It is desirable to form and adopt an annular shape extending along the circumferential direction of the outer race. According to such a configuration, the pressing force acting between the interposition member and the outer circumferential surface of the outer race can be made substantially uniform over the entire circumferential direction of the outer race, and local deformation of the outer race can be suppressed as much as possible. .

  As such an annular interposition member, in addition to the absence of a discontinuous portion in the circumferential direction, an interposition member having a C shape having a notch, for example, according to the invention of claim 4 is used. It may be adopted. Since such a C-shaped interposition member has a notch, that is, a discontinuous portion in the circumferential direction, when the member is attached to the outer peripheral side of the outer race, the diameter can be easily increased or decreased through the deformation. Can do. That is, the work of mounting the interposition member on the outer race or the retainer is facilitated.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the interposition member is formed in a groove formed in at least one of a support surface of the retainer and an outer peripheral surface of the outer race. The main point is to be accommodated.

According to this configuration, it is difficult for the interposition member to fall off between the support surface of the retainer and the outer peripheral surface of the outer race.
As the radial bearing, for example, a sliding bearing or a rolling bearing can be employed. Of these, when a rolling bearing is employed, a tapered roller bearing may be employed as the bearing, for example, as in the sixth aspect of the present invention. In this case, the durability of the bearing with respect to the axial load is improved as compared with a bearing in which the roller axis is parallel to the race axis, such as a cylindrical roller bearing.

  The invention according to claim 7 is a bearing unit comprising a thrust bearing in which a rotating side race and a fixed side race are arranged in the axial direction, and a retainer for supporting the fixed side race to restrict movement in the axial direction. And between the supported surface of the fixed side race and the support surface of the retainer that supports the fixed side race, and the supported surface of the rotating body supported by the rotating side race and the supporting surface of the same rotating side race The gist of the invention is that an interposition member made of a material having a higher linear expansion coefficient than that of the retainer is provided in at least one of the gaps.

  According to this configuration, since the interposed member is formed of a material having a higher linear expansion coefficient than the retainer, the amount of thermal expansion (expansion length) when the temperature rises to the same temperature is larger in the interposed member than in the retainer. Become. Therefore, when such a temperature rise occurs, there is a decrease in the pressing force that the supported surface of the stationary race receives from the support surface side of the retainer and the pressing force that the support surface of the rotating race receives from the supported surface side of the rotating body. It is suppressed by the thermal expansion of the member. As a result, a decrease in preload, a decrease in smoothness of rotation, and a decrease in durability of the thrust bearing are suppressed. Further, for example, as compared with the conventional mode in which the heat radiating fins are formed so as to suppress the thermal expansion of the retainer, it is possible to easily suppress the increase in size of the retainer.

  Here, the above-mentioned “thermal expansion amount” refers to the thermal expansion amount per unit length of each member. Therefore, if the “thermal expansion amount” is compared, for example, it will be compared how much the portions of the retainer and the intervening member that have the same length before thermal expansion have expanded.

  As an aspect of the bearing unit, for example, according to the invention described in claim 8, the retainer is a differential carrier that constitutes a differential device of an automobile, and the bearing can rotate a drive shaft that also constitutes the differential device. It is possible to adopt such a thing as supporting. In such a differential device, the temperature of each constituent member including the retainer is likely to increase, and there is a particular concern about a decrease in preload and a decrease in durability caused by the above-described decrease in pressing force. In that respect, according to the present invention, it is possible to suitably suppress the adverse effect caused by such a temperature rise.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a rear differential device (final reduction device) for automobiles equipped with a bearing unit of the present invention. In the following description, the upper side of FIG. 1 is assumed to be the front of the rear differential device, and the lower side is also assumed to be the rear of the device.

  As shown in the figure, an input shaft 12 to which rotational power from the engine side is transmitted is rotatably supported in the housing 11 of the rear differential device 10. The input shaft 12 is disposed so that the front end on the power input side protrudes from the housing 11, and a pinion gear 12 a is provided at the rear end located in the housing 11. In the present embodiment, the housing 11 is formed of an aluminum alloy material for the purpose of weight reduction and the like.

  The housing 11 accommodates a ring gear 13 that meshes with the pinion gear 12a and is rotationally driven by the gear 12a. The ring gear 13 is bolted to the outer periphery of a differential case 14 that is supported so that the rotation center axis is orthogonal to the input shaft 12. The differential case 14 constitutes a “rotating body” in claims.

  The differential case 14 is rotatably supported via a tapered roller bearing 17 with respect to two differential carriers 16 a and 16 b that are inserted into openings 11 a and 11 b formed in the left and right portions of the housing 11 and fixed with bolts. Drive shafts 18a and 18b having the same rotation center axis are inserted into the differential case 14 through cylindrical portions 14a and 14b protruding from the left and right portions thereof.

  The drive shafts 18a and 18b are rotatably supported by the differential case 14 with the inner peripheral surfaces of the cylindrical portions 14a and 14b as sliding bearing surfaces. In other words, the tapered roller bearing 17 supports the drive shafts 18a and 18b via the differential case 14 so as to be rotatable. In addition, the outer peripheral side of each drive shaft 18a, 18b is sealed by the annular seal member 30 provided in each differential carrier 16a, 16b.

  Driven gears 19a and 19b are fixed to the tips of the drive shafts 18a and 18b inside the differential case 14, respectively. A support shaft 20 is fixed to the differential case 14 so as to extend in a direction perpendicular to the rotation center axis in the space between the driven gears 19a and 19b, and the two support shafts 20 are rotatably supported by the support shaft 20. The pinion gear 21 is meshed with both the driven gears 19a and 19b.

  With this configuration, in the rear differential device 10, when the rotational power from the engine is transmitted to the input shaft 12, the ring gear 13, that is, the differential case 14 is rotationally driven with the rotation of the pinion gear 12a. The rotation is transmitted to the gears 21, 19a, 19b through the support shaft 20, so that the drive shafts 18a, 18b and eventually the driving wheels of the automobile are driven to rotate. Further, based on the rotation of each pinion gear 21 around the support shaft 20, the differential between the driven gears 19a and 19b, that is, the drive shafts 18a and 18b, is allowed.

Hereinafter, a characteristic configuration of the present embodiment will be described.
In this embodiment, each differential carrier 16a, 16b has an annular shape surrounding each drive shaft 18a, 18b in the circumferential direction, and is formed using an aluminum alloy material for the purpose of weight reduction or the like. Each of the tapered roller bearings 17 is interposed between the outer peripheral surfaces 14c and 14d of the cylindrical portions 14a and 14b of the differential case 14 and the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b, which function as radial bearings. . The tapered roller bearing 17 is excellent not only in the radial load but also in the axial load. In this embodiment, the tapered roller bearing 17 is also used for restricting the axial movement of the differential case 14. That is, in this embodiment, the tapered roller bearing 17 is also used as a thrust bearing.

  That is, the outer race 17a of each tapered roller bearing 17 is supported by the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b, and the inner race 17b supports the outer peripheral surfaces 14c and 14d of the differential case 14. In other words, each of the differential carriers 16 a and 16 b functions as a retainer that supports the tapered roller bearing 17, and the inner peripheral surfaces 16 c and 16 d function as support surfaces that support the outer peripheral surface 17 d of the outer race 17 a of the bearing 17.

  Each of the races 17a and 17b of the tapered roller bearing 17 and the tapered roller 17c disposed between them is formed using a steel-based material. Incidentally, the steel-based material has a smaller linear expansion coefficient than the aluminum alloy material.

  The preload (preload) in each tapered roller bearing 17 increases and decreases with a change in the relative position between the outer race 17a and the inner race 17b in the axial direction (left-right direction). In this embodiment, the races 17a and 17b are pressed against the differential case 14 side by the differential carriers 16a and 16b via the annular shims 22a and 22b, thereby generating a preload. In other words, the shims 22a and 22b are provided on the support surfaces 16e and 16f of the differential carriers 16a and 16b for supporting the outer races 17a in order to restrict the movement of the outer races 17a in the axial direction, and the outer races 17a supported by the shims 22a and 22b. It arrange | positions so that it may interpose between the support surfaces 17e. For adjusting the preload, an appropriate thickness is selected from a plurality of shims 22a and 22b having different thicknesses, and this is adopted when the differential carriers 16a and 16b are assembled to the housing 11. To do so.

  Incidentally, in the tapered roller bearing 17 that also functions as a thrust bearing as described above, each outer race 17a corresponds to a fixed side race in claims, and each inner race 17b similarly corresponds to a rotation side race. In addition, the annular surfaces 17f facing each other among the surfaces facing the axial direction in the left and right inner races 17b correspond to support surfaces that support the differential case 14 as a rotating body so as to restrict the movement in the axial direction. The annular surface 14e of the differential case 14 supported by these surfaces 17f corresponds to a supported surface.

  By the way, when the temperature of the rear differential device 10 rises due to heat transfer from the engine or the exhaust pipe, the housing 11, the differential carriers 16a and 16b, the tapered roller bearing 17 and the like are deformed due to thermal expansion. Here, in particular, in the embodiment in which the aluminum alloy material is used for the housing 11 and the differential carriers 16a and 16b as described above, the linear expansion coefficient of the aluminum alloy material is larger than that of the steel-based material. The housing 11 and the differential carriers 16 a and 16 b are larger than the tapered roller bearing 17 with respect to the amount of thermal expansion (expansion length) when it is raised.

  In this case, if the surface pressure acting on the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b and the outer peripheral surface 17d of the outer races 17a is reduced due to such a difference in thermal expansion amount, the preload is thereby increased. There is a concern that the smooth rotation of the tapered roller bearing 17 is impaired or the durability thereof is lowered.

  Therefore, in the present embodiment, as shown in FIG. 2, a line is formed between the outer peripheral surface 17d of each outer race 17a and the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b. A C-ring 25 formed using a material having a high expansion coefficient is interposed. In FIG. 2, only the right side of FIG. 1, that is, the differential carrier 16b side is shown, and the other differential carrier 16a side has the same configuration and is not shown.

  Each C-ring 25 is formed using a polyetherimide (PEI) resin, and has a shape in which a notch is provided in an annular member extending along the circumferential direction of the outer race 17a. Each C-ring 25 is accommodated in an annular groove 26 formed in the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b.

  In this embodiment, the tapered roller bearings 17 are assembled to the differential carriers 16a and 16b in a substantially normal temperature environment, and in this state, the dimensions are set so that the tightening force of the C-ring 25 against the outer races 17a hardly acts. Has been. Further, in this state, these are set to substantially the same radial dimension and axial dimension so that there is almost no gap between the groove surface of each annular groove 26 and the outer surface of the C-ring 25.

Hereinafter, the operation and the like of the C-ring 25 will be described with reference to FIG.
FIG. 3 (a) illustrates the force acting on the tapered roller bearing 17 in the above-described state at substantially normal temperature. FIG. 3 (b) shows that the temperature rises from that state and thermal expansion occurs in each member. The force that acts on the tapered roller bearing 17 in the above state will be described. 3 also illustrates only the differential carrier 16b side as in FIG. In FIG. 3, for the convenience of explanation, the surface pressure acting on each member is replaced with a force acting on one point on the surface and is displayed as a vector.

  In the state shown in FIG. 3A, when the differential carrier 16b is assembled to the housing 11, the pressing force F1 in the axial direction (leftward in the figure) from the shim 22b acts on the outer race 17a of the tapered roller bearing 17. Due to this, the pressing force F2 from the inner peripheral surface 16d of the differential carrier 16b acts on the outer peripheral surface 17d of the race 17a. In this state, the force from the C ring 25 does not act on the outer peripheral surface 17d of the outer race 17a. Accordingly, a pressing force F3 corresponding to the resultant force of the pressing forces F1 and F2 acts on the outer peripheral surface of the tapered roller 17c. The preload in the tapered roller bearing 17 is correlated with the pressing force F3.

  On the other hand, in the state shown in FIG. 3B, since the linear expansion coefficient of the differential carrier 16b is larger than that of the outer race 17a, the differential carrier 16b is larger than the outer race 17a with respect to the expansion amount in the thermal expansion. At this time, even if the above-described pressing force F2 is reduced due to the difference in the amount of thermal expansion (in FIG. 3B, the pressing force F2 is reduced to “0”), the linear expansion coefficient is A pressing force F4 from the C ring 25 acts on the outer peripheral surface 17d of the outer race 17a due to thermal expansion of the C ring 25 which is larger than that of the differential carrier 16b. Accordingly, a pressing force F5 corresponding to the resultant force of the pressing forces F1 and F4 acts on the outer peripheral surface of the tapered roller 17c, and the preload in the tapered roller bearing 17 is correlated with the pressing force F5. That is, when the pressing force F4 from the C ring 25 is generated, the decrease in the preload due to thermal expansion is suppressed.

  Needless to say, since the reaction force (not shown) of the pressing force F4 is applied to the differential carrier 16b from the C ring 25 at this time, the holding force for holding the outer race 17a by the differential carrier 16b. The decrease in the pressure is also suppressed.

In the present embodiment, the tapered roller bearing 17 and the differential carriers 16a and 16b that support the tapered roller bearing 17 and the C ring 25 constitute a “bearing unit” in the claims.
Thus, in the present embodiment, a material having a higher linear expansion coefficient than the differential carriers 16a and 16b between the outer peripheral surface 17d of the outer race 17a and the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b that support the outer race 17a. A C-ring 25 is provided as an interposed member made of As a result, the C ring 25 is larger than the differential carriers 16a and 16b with respect to the amount of thermal expansion when the temperature rises to the same temperature, so that the outer peripheral surface 17d of the outer race 17a becomes the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b. The reduction in the pressing force received from the side is suppressed by the thermal expansion of the C ring 25. As a result, a decrease in preload and a decrease in smoothness of rotation in the tapered roller bearing 17 and a decrease in durability thereof are suppressed.

  Further, for example, as compared with the conventional mode in which the heat dissipating fins are formed so as to suppress the thermal expansion of the retainer, it is possible to easily suppress the increase in size of the retainer and hence the rear differential device 10.

  In particular, when the differential carriers 16a and 16b are formed of a material having a higher linear expansion coefficient than the outer race 17a as in the present embodiment, the outer peripheral surface 17d of the outer race 17a is from the inner peripheral surfaces 16c and 16d side of the differential carriers 16a and 16b. The phenomenon that the received pressing force decreases as the temperature of these members rises becomes even more pronounced. In that respect, according to the above-described configuration in which the C-ring 25 made of a material having a higher linear expansion coefficient than the differential carriers 16a and 16b is provided, such a decrease in the pressing force is suitably suppressed by the thermal expansion of the C-ring 25. .

  Further, in the present embodiment, the rear differential device 10 is easily heated by the exhaust heat of the automobile, that is, the temperature is likely to rise. Therefore, the thermal expansion of the C-ring 25 is suppressed in order to suppress the reduction of the pressing force. Will be particularly useful.

  Moreover, since the annular C ring 25 extending along the circumferential direction of the outer race 17a is employed as the interposition member, it acts between the interposition member (C ring 25) and the outer peripheral surface 17d of the outer race 17a. The pressing force can be made substantially uniform over most of the circumferential direction, and local deformation of the outer race 17a can be suppressed as much as possible.

  Since the C ring 25 has a C shape with a notch, the diameter can be easily reduced through deformation when the C ring 25 is incorporated into the annular groove 26. That is, the work of mounting the interposition member on the differential carriers 16a and 16b is facilitated.

  Further, since the C-ring 25 is accommodated in the annular groove 26 as described above, it is difficult for the C-ring 25 to fall off between the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b and the outer peripheral surface 17d of the outer race 17a.

  Further, in the present embodiment, the tapered roller bearing 17 is used to support the drive shafts 18a and 18b, so that, for example, a cylindrical roller bearing or the like is compared with a bearing whose roller axis is parallel to the axis of the drive shafts 18a and 18b. Thus, the durability of the bearing against an axial load is improved.

In addition, embodiment is not limited above, For example, it is good also as the following aspects.
-For example, in the aspect in which the thermal expansion such that the distance in the axial direction between the supported surface 14e of the differential case 14 and the support surfaces 16e, 16f of the differential carriers 16a, 16b increases as the temperature rises occurs in the rear differential device 10, The shims 22a and 22b may be formed of a material having a higher linear expansion coefficient than the differential carriers 16a and 16b and the housing 11. Examples of this material include PEI resin as described above. According to this configuration, the decrease in the pressing force that the supported surface 17e of the outer race 17a receives from the side of the support surfaces 16e and 16f of the differential carriers 16a and 16b is suppressed by the thermal expansion of the shims 22a and 22b. The decrease in the preload at 17 is suppressed. That is, in the present configuration, the shims 22a and 22b function as “intervening members” in the claims.

  In the description of FIG. 3 above, the pressing force acting on the outer peripheral surface 17d of the outer race 17a is almost only the pressing force F2 from the inner peripheral surfaces 16c, 16d of the differential carriers 16a, 16b in the environment of substantially normal temperature, and the C ring The pressing force F4 from 25 is assumed to act after thermal expansion occurs from this state, but the present invention is not limited to this. That is, instead of this, for example, the dimension of the C ring 25 may be set so that the pressing force from the C ring 25 acts on the outer peripheral surface 17d of the outer race 17a before the occurrence of the thermal expansion. In this case, with the occurrence of the thermal expansion, the pressing force from the C-ring 25 becomes larger than before the occurrence of the thermal expansion, thereby suppressing a decrease in the preload of the tapered roller bearing 17 due to the temperature increase. Become. In this manner, in the aspect in which the pressing force from the C ring 25 acts before the occurrence of the thermal expansion, the pressing force F2 is not generated before the occurrence of the thermal expansion, that is, the C ring 25. The shape and size of each member may be set so that only the pressing force from the outer peripheral surface 17d acts on the outer peripheral surface 17d, or the pressing force from both acts on the outer peripheral surface 17d. Further, after the occurrence of the thermal expansion, the pressing force F4 is not limited to the configuration in which only the pressing force F4 from the C ring 25 acts on the outer peripheral surface 17d of the outer race 17a as described in the description of FIG. And the pressing force F2 may be configured to act on the outer peripheral surface 17d.

  In the above embodiment, the annular groove 26 that accommodates the C-ring 25 is provided on the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b. It may be provided. Moreover, you may make it provide not only one of these inner peripheral surfaces 16c and 16d and the outer peripheral surface 17d but an annular groove in both. It is to be noted that an aspect in which an annular groove is provided and a C-ring is accommodated in this manner is not essential. For example, the C-ring is interposed between the inner peripheral surfaces 16c and 16d and the outer peripheral surface 17d without providing such a groove. It may be.

  -Although the aspect which employ | adopted the C ring 25 which has the said notch (part discontinuous in the circumferential direction) as an interposition member was illustrated above, it is not restricted to this, For example, the annular member which does not have such a notch is used. You may make it provide between the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b and the outer peripheral surface 17d of the outer race 17a. In addition to these annular members, for example, as shown in FIG. 4, the inner peripheral surfaces 16c, 16d of the differential carriers 16a, 16b and the outer races 17a, such as in the annular groove 26, using a plurality of block-like members 41 as the interposing members. The outer peripheral surface 17d may be dispersed in the circumferential direction. In the configuration employing the non-circular interposed member as described above, when the groove for accommodating the interposed member is provided on the inner peripheral surfaces 16c and 16d of the differential carriers 16a and 16b and the outer peripheral surface 17d of the outer race 17a, The groove need not be annular like the annular groove 26. For example, an aspect in which a non-annular groove capable of accommodating the member is formed only at the position where the interposed member is disposed may be employed.

  In the above embodiment, the tapered roller bearing 17 is employed as the radial bearing. However, the present invention is not limited to this, and other radial bearings such as a cylindrical roller bearing 51 as illustrated in FIG. 5 may be employed. The cylindrical roller bearing 51 includes a cylindrical roller 51c having an axis parallel to the outer race 51a and the inner race 51b. A C ring 52 is provided as an interposed member between the inner peripheral surface (support surface) 53a of the differential carrier (retainer) 53 and the outer peripheral surface 51d of the outer race 51a. The C ring 52 is accommodated in an annular groove 54 formed on the inner peripheral surface 53 a of the differential carrier 53. In this case, due to the thermal expansion of the C ring 52, the decrease in the preload of the cylindrical roller bearing 51 accompanying the temperature rise is suppressed as described above.

  Further, as shown in the figure, the differential case 14 may be supported using a thrust bearing 55. The thrust bearing 55 includes a rotation side race 55 a that comes into contact with the differential case 14 and a fixed side race 55 b that comes into contact with the differential carrier 53 via the shim 22. A plurality of balls 55c are provided as rolling elements between the races 55a and 55b. The constituent members of the thrust bearing 55 (the races 55a and 55b and the balls 55c) are each formed of a steel material. The shim 22 includes a support surface 53b of the differential carrier 53 that supports the race 55b so as to restrict movement of the fixed race 55b in the axial direction, and a supported surface 55d of the fixed race 55b that faces the shim 22b. It is provided in between. The shim 22 is formed of a material (for example, PEI resin) having a higher linear expansion coefficient than the differential carrier 53 and the housing 11. In this case, due to the thermal expansion of the shim 22, as described above, a decrease in the preload of the thrust bearing 55 and a decrease in the smoothness of rotation due to a temperature increase, and a decrease in the durability thereof are suppressed. That is, in this configuration, the shim 22 functions as an “intervening member” in the claims. In the above example, the shim 22 is provided between the support surface 53b of the differential carrier 53 and the supported surface 55d of the fixed side race 55b. Instead, for example, a differential case supported by the rotation side race 55a. The shim 22 may be provided between the 14 supported surfaces 14f and the support surface 55e of the rotation side race 55a facing the 14 supported surfaces 14f.

  In the above embodiment, the PEI resin is used as the constituent material of the interposition member. However, the present invention is not limited to this, and other materials may be used as long as the material has a higher linear expansion coefficient than the retainer, such as the differential carriers 16a and 16b. May be.

-In the said embodiment, although the rolling bearing was employ | adopted as a bearing, not only this but the sliding bearing which does not have rolling elements, such as a roller and a ball | bowl, may be employ | adopted.
In the above embodiment, the drive shafts 18a and 18b are supported by the bearing via the differential case 14, but the present invention is not limited to this. For example, the drive shafts 18a and 18b may be directly supported by the bearing without using the differential case 14.

  In the above embodiment, the retainer (for example, the differential carriers 16a, 16b, and 53) is formed of a material having a higher linear expansion coefficient than the bearing race, but such a configuration is not essential. Even if the retainer and the race are not in such a relationship of the linear expansion coefficient, for example, when the retainer tends to be higher in temperature than the race, the retainer tends to be larger than the race. Can suitably suppress the decrease in the preload in the bearing through the application of the present invention.

  In the above description, the bearing unit of the present invention is applied to the rear differential device 10 for automobiles. However, the present invention is not limited to this and may be applied to other mechanisms.

1 is a cross-sectional plan view showing an overview of a rear differential device according to an embodiment. Sectional drawing in the 2-2 line of FIG. (A), (b) is a figure explaining the force which acts on a tapered roller. The figure which shows the cross-sectional shape of the part corresponded to the 2-2 line | wire of FIG. 1 about another example. The expanded sectional view about the example which employ | adopted the other bearing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Rear differential apparatus, 11 ... Housing, 13 ... Ring gear, 14 ... Differential case, 14e, 14f ... Supported surface of differential case, 16a, 16b ... Differential carrier, 16c, 16d ... Inner peripheral surface of differential carrier, 16e, 16f ... Differential carrier support surface, 17 ... tapered roller bearing, 17a ... outer race, 17b ... inner race, 17c ... tapered roller, 17d ... outer race outer circumferential surface, 17e ... outer race supported surface, 17f ... inner race support surface, 18a , 18b ... drive shaft, 22, 22a, 22b ... shim, 25, 52 ... C-ring, 26, 54 ... annular groove, 41 ... block member, 51 ... cylindrical roller bearing, 51a ... outer race, 51b ... inner race, 51c ... Roller, 51d ... Outer race of outer race, 53 ... Differential carrier, 53a ... Inner circumferential surface of carrier, 53b ... Differential carrier support surface, 55 ... Thrust bearing, 55a ... Rotation side race, 55b ... Fixed side race, 55c ... Ball, 55d ... Supported surface of fixed side race, 55e ... Rotation side Race support surface.

Claims (8)

A bearing unit comprising a radial bearing having an outer race and an inner race, and a retainer for supporting the outer race,
An interposition member made of a material having a higher linear expansion coefficient than the retainer is provided between the outer peripheral surface of the outer race and the support surface of the retainer that supports the outer race on the outer peripheral surface. The bearing unit according to claim 1,
The retainer is formed of a material having a higher linear expansion coefficient than the outer race. The bearing unit according to claim 1 or 2,
The interposition member has an annular shape extending along a circumferential direction of the outer race. The bearing unit according to claim 3, wherein
The bearing unit has a C shape with a notch. In the bearing unit as described in any one of Claims 1-4,
The said interposition member is accommodated in the groove | channel formed in at least one of the support surface of the said retainer, and the outer peripheral surface of the said outer race. The bearing unit characterized by the above-mentioned. In the bearing unit as described in any one of Claims 1-5,
A tapered roller bearing is adopted as the radial bearing. A bearing unit comprising a thrust bearing in which a rotating side race and a fixed side race are arranged in an axial direction, and a retainer that supports the thrust side race to restrict movement in the axial direction of the fixed side race,
At least between the supported surface of the fixed race and the support surface of the retainer that supports the fixed race, and between the supported surface of the rotating body supported by the rotating race and the support surface of the rotating race. On one side, an interposition member made of a material having a higher linear expansion coefficient than the retainer is provided. In the bearing unit as described in any one of Claims 1-7,
The retainer is a differential carrier that constitutes a differential device of an automobile, and the bearing rotatably supports a drive shaft that also constitutes the differential device.

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