JP4359944B2 - Bearing support device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bearing support structure, and more particularly to a bearing support device that supports a pair of bearings attached to a shaft in a state where a load in the axial direction is applied to the bearings.
[0002]
[Prior art]
Bearings that can load radial loads and unidirectional thrust loads, such as tapered roller bearings and single-row angular contact ball bearings, are usually arranged with two bearings facing each other along the shaft so that thrust loads in both directions can be loaded. Used in. These two bearings are supported by bearing support portions in the mechanical structure. At this time, in general, the distance between the inner rings or the outer rings of both the bearings is adjusted in the axial direction, whereby each bearing has a predetermined axial direction. The preload is applied. Such a preload is effective in preventing fluctuations in the bearing gaps of the bearings due to external forces, and in particular preventing misalignment of both bearings during high-speed rotation.
[0003]
FIG. 4 shows an example of such a conventional bearing and bearing support structure. In the illustrated example, a pair of tapered roller bearings 2 and 3 are attached to the shaft 1 so as to face each other. The shaft 1 includes an overhanging portion 1a that supports the inner ring 2a of one tapered roller bearing 2, and includes a male screw portion 1b at the shaft end, and the inner ring 3a of the other tapered roller bearing 3 is adjacent to the male screw portion 1b. Arranged. These tapered roller bearings 2 and 3 are arranged in a so-called rear combination form, and a plurality of spacers 4 and 5 are installed between the inner rings 2a and 3a to maintain the distance between the inner rings 2a and 3a. .
[0004]
The shaft 1 is received in a non-contact manner in a hole 6a formed through the bearing support 6 in the mechanical structure. The outer rings 2 b and 3 b of the pair of tapered roller bearings 2 and 3 are fitted into annular recesses 6 b formed at both ends of the hole 6 a of the bearing support portion 6. In this state, the nut 7 is screwed onto the male thread portion 1 b of the shaft 1, and the inner rings 2 a and 3 a of the both bearings 2 and 3 and the plurality of spacers 4 and 5 are fixed to the shaft 1.
[0005]
The interval between the inner rings 2 a and 3 a of the tapered roller bearings 2 and 3 is defined by the axial dimensions of the plurality of spacers 4 and 5. On the other hand, the distance between the outer rings 2 b and 3 b of the both tapered roller bearings 2 and 3 is defined by the distance between both annular recesses 6 b of the bearing support 6. Accordingly, when the nut 7 is screwed onto the shaft 1, the total axial dimension of the plurality of spacers 4, 5, that is, the double tapered roller bearings, so that a predetermined preload is applied to the bearings 2, 3 in the axial direction. A target value for the interval between the inner rings 2a and 3a is set. These spacers 4 and 5 have a cylindrical spacer 4 having an axial dimension slightly shorter than the target value, and the interval is adjusted by supplementing the cylindrical spacer 4 so that the total axial dimension can be easily adjusted. And an annular spacer (or shim) 5 having a small axial dimension.
[0006]
[Problems to be solved by the invention]
In the conventional bearing support structure described above, when the total axial dimension of the plurality of spacers 4 and 5 becomes larger than the target value, it becomes impossible to apply a predetermined preload to the bearings 2 and 3. Therefore, normally, one cylindrical spacer 4 and a desired number of annular spacers 5 are used by being stacked on the shaft 1 in the axial direction until the total dimension thereof approaches the target value. In this case, since it is difficult to accurately match the total axial dimension of the plurality of spacers 4 and 5 with the target value, the gap between the inner rings 2a and 3a of the tapered roller bearings 2 and 3 and the spacers 4 and 5 is difficult. Usually, a slight gap is left. Then, by adjusting the tightening torque of the nut 7, the distance between the inner rings 2a, 3a of the tapered roller bearings 2, 3 is finely adjusted around the target value, and a predetermined pre-load is applied to each bearing 2, 3 in the axial direction. A load is applied.
[0007]
However, at this time, if excessive tightening torque is applied due to inadequate adjustment of the tightening torque of the nut 7, and the gap between the inner rings 2a, 3a of the tapered roller bearings 2, 3 and the spacers 4, 5 is reduced more than necessary, Since the space between the outer rings 2b and 3b of the tapered roller bearings 2 and 3 is not substantially reduced due to the structure of the bearing support 6, the preload applied to the bearings 2 and 3 becomes excessive, and the rolling elements are rotated during shaft rotation. There is a risk of damage such as seizure. On the other hand, if the tightening torque of the nut 7 is too small, the preload applied to the tapered roller bearings 2 and 3 is insufficient, and the bearing gap between the bearings 2 and 3 is easily expanded and stabilized by the thrust load at the time of shaft rotation. There is a risk that it will be difficult to support the shaft. In addition, in this case, even if the tightening torque of the nut 7 is slightly varied, the preload to each bearing easily varies. Therefore, in the above configuration, it is essential to strictly manage the tightening torque of the nut 7.
[0008]
However, in order to strictly manage the tightening torque of the nut, there is a problem that the equipment cost of the tightening device or the like generally increases. However, it is difficult to strictly control the tightening torque with a relatively inexpensive impact wrench. Therefore, conventionally, by improving the dimensional accuracy of the spacers arranged between both bearings, especially the annular spacer (shim) for adjusting the interval, the total axial dimension of the plurality of spacers is approximated to the target value as much as possible. Measures were taken to properly adjust the preload applied to each bearing while restraining the increase in capital investment costs. However, it is difficult to improve the dimensional accuracy of the spacer to such an extent that fluctuations in the preload due to variations in the tightening torque of the nut can be eliminated, and it is still impossible to cope with higher performance of the bearing function.
[0009]
An object of the present invention is a bearing support device for supporting a pair of bearings attached to a shaft in a state where a preload is applied, and it is necessary to strictly control a tightening torque of a nut for fixing the bearings to the shaft. Bearing support that can properly adjust the preload in the axial direction applied to each bearing and promote high performance of the bearing function without depending on the dimensional accuracy of the spacer that defines the distance between both bearings To provide an apparatus.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a pair of tapered roller bearings attached to a shaft portion of a drive pinion of a final reduction gear of a power transmission mechanism is provided in the axial direction on these tapered roller bearings. In the bearing support device that supports in a state in which a load is applied, it includes an elastic structure to which each fixed-side bearing ring of the pair of tapered roller bearings is attached, and the elastic structure has a free end and a fixed end. And a base portion that supports the member at a fixed end, and the elastically deformable member and the base portion are a pair of tapered roller bearings and a shaft portion to which the tapered roller bearings are attached. forming a housing assembly for housing the fixed side raceway of the one tapered roller bearing is attached to the free end of the elastically deformable member, the fixed side raceway of the other tapered roller bearings in the base is mounted, free Take to the edge By the elastic restoring force of the member when the only fixed bearing ring is flexed member to approach the fixed bearing ring attached to the base, that the load in the axial direction is applied to each of the pair of tapered roller bearings A bearing support device is provided.
[0012]
According to a second aspect of the present invention, there is provided the bearing support device according to the first aspect, further comprising at least one spacer disposed between the rotation-side raceways of the pair of tapered roller bearings. I will provide a.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on the embodiments with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by common reference numerals.
FIG. 1 conceptually shows a bearing support device according to the present invention. As shown in FIG. 1, the bearing support device according to the present invention is characterized by including an elastic structure 10 to which each fixed-side bearing ring of a pair of bearings attached to a shaft is attached.
[0014]
As in the prior art of FIG. 4, the shaft 12 is provided with an inner ring 14a of one tapered roller bearing 14 adjacent to the overhanging portion 12a, that is, a rotating raceway, and adjacent to the male threaded portion 12b at the shaft end. The inner ring 16 a of the other tapered roller bearing 16, that is, the rotating side race ring is attached. These tapered roller bearings 14 and 16 are arranged in a so-called rear combination form, and a plurality of spacers 18 and 20 are installed between the inner rings 14a and 16a to maintain the distance between the inner rings 14a and 16a. .
[0015]
The outer rings 14b and 16b of each of the pair of tapered roller bearings 14 and 16, that is, the fixed-side raceways are respectively fitted into annular recesses 10a formed outwardly from the elastic structure 10 so as to be away from each other. In this state, the nut 22 is screwed onto the male screw portion 12 b of the shaft 12, and the inner rings 14 a and 16 a and the plurality of spacers 18 and 20 of both the bearings 14 and 16 are fixed to the shaft 12.
[0016]
The interval between the inner rings 14a, 16a of the tapered roller bearings 14, 16 is defined by the axial dimensions of the plurality of spacers 18, 20. On the other hand, the distance between the outer rings 14 b and 16 b of the both tapered roller bearings 14 and 16 is defined by the distance between the annular recesses 10 a of the elastic structure 10. Therefore, when the nut 22 is screwed onto the shaft 12, the plurality of spacers 18, so that a predetermined preload is applied to the bearings 14, 16 in the axial direction under the elastic restoring force of the elastic structure 10. A total dimension of 20 in the axial direction, that is, a target value of the interval between the inner rings 14a and 16a of the tapered roller bearings 14 and 16 is set. The spacers 18 and 20 have a cylindrical spacer 18 having an axial dimension somewhat shorter than the target value and a cylindrical spacer 18 that is used as a supplement so that the total axial dimension can be easily adjusted. And an annular spacer (or shim) 20 having a small axial dimension.
[0017]
In the bearing support device according to the present invention, since the outer rings 14b and 16b of the double tapered roller bearings 14 and 16 are elastically supported by the elastic structure 10, the double tapered roller bearing 14 is tightened by tightening the nut 22, as described above. The outer rings 14b, 16b of the sixteen and sixteen approach each other, and a predetermined preload in the axial direction is applied to the bearings 14, 16 in a state where the elastic structure 10 is bent to some extent. Therefore, if the total axial dimension of the plurality of spacers 18 and 20 is larger than the target value described above, the inner rings 14a and 16a of the tapered roller bearings 14 and 16 will contact the spacers 18 and 20 when the nut 22 is tightened. Even if the elastic structure 10 is slightly bent in the range until contact, a predetermined preload cannot be applied to the bearings 14 and 16.
[0018]
Therefore, similarly to the above-described prior art, one cylindrical spacer 18 and a desired number of annular spacers 20 are used by being stacked in the axial direction on the shaft 12 until their total dimensions approach the target value. In this case, the total axial dimension of the plurality of spacers 18 and 20 need not exactly match the target value, and may be stacked until an axial dimension somewhat smaller than the target value is obtained. Then, the inner ring 14a, 16a and the outer rings 14b, 16b of the tapered roller bearings 14, 16 are brought close to each other by tightening the nut 22, and elastic until the inner rings 14a, 16a are brought into contact with the spacers 18, 20. The structure 10 is bent. Here, by adjusting the tightening torque of the nut 22 to finely adjust the distance between the inner rings 14a, 16a of the tapered roller bearings 14, 16 around the target value, the elastic restoring force of the elastic structure 10 can be reduced. Thus, a predetermined preload is applied to the bearings 14 and 16 in the axial direction.
[0019]
As described above, in the prior art, when the tightening torque of the nut 7 varies within an error range inherent in, for example, a general torque wrench, and the actual tightening torque becomes larger than a set value, the double tapered roller bearing 2, 3, the inner rings 2a and 3a approach each other until they come into contact with the spacers 4 and 5, while the outer rings 2b and 3b of both bearings 2 and 3 cannot approach each other. There is a problem that preload is applied. In order to prevent this, it is necessary to strictly control the tightening torque of the nut 7 or to improve the axial dimensional accuracy of the spacers 4 and 5.
[0020]
On the other hand, in the present invention, when the actual tightening torque of the nut 22 becomes larger than the set value due to an error, the inner rings 14a and 16a of the both tapered roller bearings 14 and 16 are brought into contact with the spacers 18 and 20. Even if it moves, the outer rings 14b, 16b of the tapered roller bearings 14, 16 can approach each other against the elastic restoring force of the elastic structure 10, so that the preload applied to the bearings 14, 16 becomes excessive. Is avoided. That is, even if the tightening torque of the nut 22 varies within an error range inherent in, for example, a general torque wrench, fluctuations in the preload applied to the bearings 14 and 16 are reduced due to elastic deformation of the elastic structure 10. It is.
[0021]
As described above, according to the bearing support device of the present invention, the fluctuation of the preload applied to the tapered roller bearings 14 and 16 caused by the variation in the tightening torque of the nut 22 is caused by the inner ring 14a of the tapered roller bearings 14 and 16. In accordance with the change in the interval between the 16a, the configuration in which the interval between the outer rings 14b and 16b can be changed under the elastic deformation of the elastic structure 10 can be effectively reduced. Therefore, the preload applied to the tapered roller bearings 14 and 16 can be appropriately adjusted without strictly managing the tightening torque of the nut 22.
[0022]
In other words, in the bearing support device of the present invention, the influence of the variation of the tightening torque of the nut 22 on the variation of the preload on the tapered roller bearings 14 and 16 is caused by the spacers 18 and 20, particularly the annular spacer 20. It is smaller than the influence of the dimensional change in the axial direction. In other words, when the total axial dimension of the plurality of spacers 18 and 20 actually used is smaller than the target value by a dimension close to one of the annular spacers 20 for adjusting the distance, variation in the tightening torque of the nut 22 varies. Even if the inner rings 14a and 16a of both tapered roller bearings 14 and 16 move until they abut against the spacers 18 and 20, fluctuations in the preload applied to the bearings 14 and 16 due to elastic deformation of the elastic structure 10 It doesn't get that big. In this case, only by slightly increasing the dimensional accuracy of the plurality of spacers 18, 20, particularly the annular spacer 20, which define the distance between the two bearings 14, 16, the effect of preventing fluctuations in the preload can be achieved. It will be understood that there is a significant improvement.
[0023]
FIG. 2 shows a bearing support device according to an embodiment of the present invention. This bearing support device is an elastically deformable attachment having a free end 24a and a fixed end 24b as an elastic structure to which outer rings 14b, 16b of a pair of tapered roller bearings 14, 16 attached to a shaft 12 are attached. The member 24 and the base part 26 which supports the attachment member 24 with the fixed end 24b are provided. The other configuration is substantially the same as that shown in FIG.
[0024]
The attachment member 24 has a hook-like shape, and is fixed to the base portion 26 by a plurality of bolts 28 at a fixed end 24b formed in a flange shape on the outer peripheral edge. The free end 24 a of the mounting member 24 defines a through hole 30 that receives the shaft 12 in a non-contact manner at the approximate center of the mounting member 24. Further, a sleeve portion 32 extending in a direction away from the base portion 26 is formed at the free end 24 a of the mounting member 24, thereby forming an outward annular recess 34 adjacent to the through hole 30. A through hole 36 for receiving the shaft 12 in a non-contact manner is formed in the base portion 26 at a position overlapping the through hole 30 of the mounting member 24 in the axial direction. An outward annular recess 38 is formed in the through hole 36 of the base 26 on the side away from the mounting member 24. The outer ring 14 b of one tapered roller bearing 14 attached to the shaft 12 is fitted into the annular recess 38 of the base portion 26, and the outer ring 16 b of the other tapered roller bearing 16 is fitted into the annular recess 34 of the mounting member 24. The
[0025]
In this embodiment, when the nut 22 is tightened, as the inner rings 14a and 16a of the tapered roller bearings 14 and 16 approach each other in a range until they abut against the plurality of spacers 18 and 20, the base portion 26, the free end 24a side of the mounting member 24 is elastically bent as shown in the drawing to allow the outer rings 14b and 16b to approach each other. Therefore, by adjusting the tightening torque of the nut 22, a predetermined preload can be applied to the bearings 14 and 16 in the axial direction under the elastic restoring force of the elastic structure 10. The operational effects of such a configuration are as described with reference to FIG.
[0026]
In the above embodiment, an elastic member such as a spring can be interposed between the free end 24 a of the mounting member 24 and the base portion 26. Thereby, the degree of elastic deformation of the elastic structure with respect to the variation in the tightening torque of the nut 22, that is, the degree of fluctuation of the preload applied to the bearings 14, 16 can be appropriately changed. Alternatively, the attachment member 24 itself can be formed from a spring.
[0027]
FIG. 3 shows an example of an application form of the bearing support device according to the present invention. In this example, the bearing support device is used for a pair of tapered roller bearings 54 and 56 for rotatably supporting the drive pinion 52 on the housing assembly 50 in the final reduction gear of the power transmission mechanism. .
[0028]
In the illustrated final reduction gear, the housing assembly 50 includes a base 58, a first mounting member 62 fixed to the base 58 by a plurality (only one shown) of bolts 60, and a plurality (only one shown) of bolts. And a second mounting member 66 fixed to the first mounting member 62 by 64. One tapered roller bearing 54 attached to the shaft portion 52a of the drive pinion 52 has its outer ring 54a fitted in the annular recess 62a of the first mounting member 62, and the other tapered roller bearing 56 has its outer ring 56a in the first position. 2 is fitted into the annular recess 66a of the mounting member 66. A power transmission gear 68 is disposed between the tapered roller bearings 54 and 56. A nut 70 is screwed to the axial front end of the shaft portion 52a of the drive pinion 52 to fix the pair of tapered roller bearings 54 and 56 and the power transmission gear 68 to the shaft portion 52a and to preload the bearings 54 and 56. Adjusted to add.
[0029]
In this case, the power transmission gear 68 disposed between the pair of tapered roller bearings 54 and 56 has the function of the cylindrical spacer 18 described in FIG. Therefore, in order to apply an appropriate preload to the bearings 54 and 56, the annular spacer 20 for adjusting the distance described with reference to FIG. 1 is disposed between the tapered roller bearings 54 and 56 and the power transmission gear 68. The first mounting member 62 of the housing assembly 50 corresponds to the base portion 26 described with reference to FIG. 2, and the second mounting member 66 corresponds to the mounting member 24 described with reference to FIG.
[0030]
In such a configuration, by using the bearing support device according to the present invention for the pair of tapered roller bearings 54 and 56 of the drive pinion 52 of the final reduction device that requires a high performance bearing function, An appropriate preload can be applied by an easy and inexpensive means. As a result, high performance of the bearing function of the pair of tapered roller bearings 54 and 56 used for the drive pinion 52 is promoted.
[0031]
【The invention's effect】
As is apparent from the above description, according to the present invention, when a preload is applied to a pair of bearings attached to the shaft, it is necessary to strictly control the tightening torque of nuts for fixing the bearings to the shaft. Bearing support that can properly adjust the preload in the axial direction applied to each bearing and promote high performance of the bearing function without depending on the dimensional accuracy of the spacer that defines the distance between both bearings An apparatus is provided.
[Brief description of the drawings]
FIG. 1 is a diagram conceptually showing a bearing support device according to the present invention.
FIG. 2 is a cross-sectional view of a bearing support device according to an embodiment of the present invention.
FIG. 3 is a sectional view of a final reduction gear device showing an application example of a bearing support device according to the present invention.
FIG. 4 is a cross-sectional view of a conventional bearing support structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Elastic structure 12 ... Shafts 14, 16 ... Conical roller bearings 14a, 16a ... Inner ring 14b, 16b ... Outer ring 18 ... Cylindrical spacer 20 ... Ring spacer 22 ... Nut 24 ... Mounting member 24a ... Free end 24b ... Fixed end 26 ... Base 28 ... Bolt

Claims (2)

In a bearing support device for supporting a pair of tapered roller bearings attached to a shaft portion of a drive pinion of a final reduction gear of a power transmission mechanism in a state where a load in the axial direction is applied to the tapered roller bearings,
Comprising an elastic structure to which each stationary bearing ring of the pair of tapered roller bearings is mounted;
The elastic structure includes an elastically deformable member having a bowl-like shape having a free end and a fixed end, and a base that supports the member at the fixed end, and the member and the base are forming a housing assembly for housing the shaft portion fitted with a pair of tapered roller bearings and their tapered roller bearings, the fixed bearing ring of one of the tapered roller bearing is mounted on the free end of the member, the The fixed side raceway of the other tapered roller bearing is attached to the base, and the member is bent so that the fixed side raceway attached to the free end approaches the fixed side raceway attached to the base. A load in the axial direction is applied to each of the pair of tapered roller bearings by the elastic restoring force of the member at the time ,
A bearing support device. The bearing support device according to claim 1, further comprising at least one spacer disposed between the rotation-side raceways of the pair of tapered roller bearings.

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