JPH11247848A - Double row tapered roller bearing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the size and weight while ensuring performance such as durability and transmission efficiency. SOLUTION: A pair of tapered roller bearings 3a, 3b supports a pinion shaft 2 having a pinion gear 4 fixed to an end. Tapered roller bearing 3a near pinion gear 4
The contact angle α of the tapered roller bearing 3b on the side opposite to the pinion gear 4 is made 5 degrees or more larger than the contact angle β. The radial rigidity of the tapered roller bearing 3a, which receives a large radial load applied from the pinion gear 4 meshing with the ring gear 5, increases. Also, the double tapered roller bearings 3a, 3b
The amount of unbalance of the axial load generated in the inside can be suppressed small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved double-row tapered roller bearing device which rotatably supports a pinion shaft constituting a differential gear provided in a drive system of an automobile in a casing.

[0002]

2. Description of the Related Art A differential gear is provided between a propeller shaft of an automobile and a driving shaft (accelerator shaft) of wheels to transmit power between the propeller shaft and the driving shaft and to change a course. The rotation speed difference between the left and right driving wheels is absorbed, and the direction of the power is further changed to perform final deceleration. Conventionally, such a differential gear is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-287617.
A structure as described in Japanese Patent Publication No. Hei. 4-51239 is known. FIG. 3 shows an example of a differential gear which is described in these publications and the like and is generally known in the related art.

In this differential gear, a pinion shaft 2 is rotatably supported inside one end of a gear case 1 by a pair of tapered roller bearings 3a and 3b constituting a double-row tapered roller bearing device to which the present invention is applied. doing. The inner end of the pinion shaft 2 (the end near the center of the gear case 1 and the left end in FIG. 3) is an inner side (the ring gear 5 side described below and the left side in FIG. 3) tapered roller bearing 3a.
A pinion gear 4 fixed to a portion protruding further than the ring gear 5 rotatably supported in the gear case 1 is meshed with each other. With such a configuration, the rotational force of a drive shaft (not shown) fixed to the outer end (the right end in FIG. 3) of the pinion shaft 2 can be transmitted to the ring gear 5 via the pinion gear 4. . Further, the rotation of the ring gear 5 can be transmitted to a pair of left and right drive shafts (not shown) supported on the gear case 1 by another tapered roller bearing (not shown).

During the operation of the differential gear as described above, a radial load is applied to the inner end of the pinion shaft 2 based on the engagement between the pinion gear 4 and the ring gear 5. Such a radial load is applied to the pair of tapered roller bearings 3a and 3b, and each of the tapered roller bearings 3a and 3b.
Axial load is generated at portions a and 3b. That is, the outer ring 6a constituting each of these tapered roller bearings 3a, 3b,
Conical concave outer raceways 7a and 7b are provided on the inner peripheral surface of 6b, and conical convex inner raceways 9a and 9b are similarly provided on the outer peripheral surfaces of the inner races 8a and 8b. A plurality of tapered rollers 10, 10 are provided between the outer raceways 7a, 7b and the inner raceways 9a, 9b so as to freely roll. Each of the above tapered roller bearings 3a, 3b
When a radial load is applied to each of the tapered rollers 10, 1
0, and the outer raceways 7a, 7b and the inner raceways constituting the tapered roller bearings 3a, 3b based on the engagement of the rolling surface 0 with the outer raceways 7a, 7b and the inner raceways 9a, 9b. A thrust load is applied in a direction that separates 9a and 9b in the axial direction.

[0005] In order to prevent the pinion shaft 2 to which the inner rings 8a and 8b are externally fitted and fixed from being displaced in the axial direction regardless of the thrust load thus generated, chain lines a and b in FIG. As shown, the directions of the contact angles of the tapered roller bearings 3a and 3b are reversed. Therefore, each of these tapered roller bearings 3a, 3b is based on the radial load.
The action directions of the axial loads generated in the pinion are opposite to each other, and any of the tapered roller bearings 3a, 3b supports this axial load even if they are offset or not offset in the pinion shaft 2, so that the pinion The shaft 2 is not displaced in the axial direction.

[0006] Such a 1 supporting the pinion shaft 2 as described above.
Conventionally, a pair of tapered roller bearings 3a, 3b having substantially the same contact angle has been used. The reason is that the magnitude of the axial load generated in each of the tapered roller bearings 3a and 3b based on the radial load is made substantially the same, and the axial load generated in each of the tapered roller bearings 3a and 3b is converted to the pinion shaft. This is because the intention was to offset as much as possible within 2. Even if the axial load cannot be offset, the contact angle of each of the tapered roller bearings 3a, 3b must be a certain value so that any of the tapered roller bearings 3a, 3b can sufficiently support the axial load. It was about big. Further, even when the radial load is applied from the pinion gear 4 to the inner end of the pinion shaft 2, the support rigidity of the pinion shaft 2 is ensured to prevent the center axis of the pinion shaft 2 from shifting. The distance between the pair of tapered roller bearings 3a and 3b is widened to increase the support span.

[0007]

In the case of the conventional structure as shown in FIG. 3, the pinion shaft 2 is required to have sufficient durability irrespective of the increase in the torque transmitted through the differential gear. A double-row tapered roller bearing for supporting and a differential gear incorporating the double-row tapered roller bearing are increased in size. That is, when the torque increases due to an increase in the output of the engine or the like, the radial load applied from the pinion gear 4 to the inner end of the pinion shaft 2 increases. In order to secure the support rigidity against the radial load with the conventional structure shown in FIG. 3, it is necessary to increase the size of the inner side tapered roller bearing 3a at least close to the pinion gear 4.

The enlargement of the tapered roller bearing 3a is as follows.
The double-row tapered roller bearing and the differential gear incorporating the double-row tapered roller bearing lead to an increase in the size of the differential gear,
This enlargement is not preferable because it leads to an increase in the weight of the automobile and a deterioration in fuel efficiency. In view of such circumstances, the present inventor considered the behavior of each component of the double-row tapered roller bearing. As a result, in order to offset the axial load generated in the pair of tapered roller bearings 3a and 3b. Has noticed that it is not necessary to make the contact angles of these two tapered roller bearings 3a, 3b the same. That is, a large radial load acts on the tapered roller bearing 3a on the inner side near the pinion gear 4, which is the input portion of the radial load, and the axial load generated in the tapered roller bearing 3a increases accordingly. On the other hand, the radial load acting on the tapered roller bearing 3b on the outer side far from the pinion gear 4 is reduced, and the axial load generated in the tapered roller bearing 3b is correspondingly reduced.

Therefore, even if the contact angle of the inner tapered roller bearing 3a is smaller than the contact angle of the outer tapered roller bearing 3b, the contact angle is generated in the tapered roller bearings 3a and 3b during operation of the differential gear. There is no significant difference in the magnitude of the axial load. On the other hand, in order to increase the radial rigidity of the tapered roller bearing and maintain the meshing state between the gear supported near the tapered roller bearing and the mating gear in a regular state, the contact angle of the tapered roller bearing is reduced. Things are preferred. The double row tapered roller bearing device of the present invention has been invented in view of such circumstances.

[0010]

The double-row tapered roller bearing device of the present invention is incorporated in the above-mentioned differential gear and has the same contact angle direction as that of the conventionally known double-row tapered roller bearing device. In the opposite direction, the first and second tapered roller bearings in which the respective outer rings are internally fitted and fixed to the fixed portion, and the inner rings of these two tapered roller bearings are internally fitted and fixed, so that they can be freely rotated on the fixed portion. And a rotating shaft supported. Then, a gear fixed to a portion projecting from the first tapered roller bearing to the opposite side from the second tapered roller bearing at one end of the rotating shaft is used in a state of being meshed with another gear.

In particular, in the double-row tapered roller bearing device of the present invention, the contact angle α of the second tapered roller bearing is set to be larger than the contact angle β of the first tapered roller bearing by 5 degrees or more. At the same time, the interval between the outer end faces of the inner ring of the two tapered roller bearings opposite to each other is set to 2.8 times or less the inner diameter of the inner ring of the second tapered roller bearing.

[0012]

According to the double-row tapered roller bearing device of the present invention configured as described above, by reducing the contact angle of the first tapered roller bearing, the radial rigidity of the first tapered roller bearing can be sufficiently increased. Can be higher. For this reason, regardless of the large radial load received from the gear fixed to the end of the rotating shaft, displacement of this gear in the radial direction can be suppressed, and the meshing state between this gear and another gear can be maintained in a normal state. When the contact angle of the first tapered roller bearing was made smaller than the contact angle of the second tapered roller bearing, and assuming that the same radial load was applied to these two tapered roller bearings, The axial load generated in the second tapered roller bearing becomes larger than the axial load generated in the first tapered roller bearing. However, in practice, the radial load acting on the first tapered roller bearing near the gear is larger than the radial load acting on the second tapered roller bearing far from the gear. Therefore, there is no large difference between the axial loads generated inside the first and second tapered roller bearings.

[0013]

1 and 2 show an embodiment of the present invention. The feature of the present invention lies in the outer side of the second tapered roller bearing (the side farther from the pinion gear 4 that receives a radial load during operation, the right side in FIGS. 1 and 2).
The contact angle α of the tapered roller bearing 3b is larger than the contact angle β of the tapered roller bearing 3a on the inner side (closer to the pinion gear 4 and on the left side in FIGS. 1 and 2) which is the first tapered roller bearing. Thus, the required tapered roller bearings 3a and 3b are narrowed while securing the required rigidity, thereby enabling reduction in size and weight. Since the structure and operation of the other parts are the same as those of the conventional structure shown in FIG.
The same parts are denoted by the same reference numerals, and duplicate description will be omitted or simplified. Hereinafter, the description will focus on the characteristic parts of the present invention.

The contact angle α of the tapered roller bearing 3b on the outer side is larger than the contact angle β of the tapered roller bearing 3a on the inner side by 5 degrees or more (α ≧ β + 5 °).
In this case, preferably, the contact angle α of the outer-side tapered roller bearing 3b is 34 degrees or less, and the contact angle β of the inner-side tapered roller bearing 3a is 12 degrees or more (12 ° ≦ β, β + 5). ° ≦ α ≦ 34 °). The reason for setting the contact angle β of the tapered roller bearing 3a on the inner side to 12 degrees or more is to increase the radial rigidity of the tapered roller bearing 3a, but to secure the required axial rigidity. In addition, both outer and inner tapered roller bearings 3
The reason why the difference between the contact angles α and β of b and 3a is 5 degrees or more is as follows.
The axial rigidity of the tapered roller bearing 3b on the outer side is increased to sufficiently support the axial load generated in the tapered roller bearing 3a on the inner side based on the large radial load applied from the pinion gear 4 meshing with the ring gear 5. To make it possible. Further, the reason why the contact angle α of the tapered roller bearing 3b on the outer side is set to 34 degrees or less is to increase the axial rigidity of the tapered roller bearing 3b, but to secure the required radial rigidity.

Further, the length of the pinion shaft 2 is reduced, and the inner ring 8 constituting the double tapered roller bearings 3a, 3b is formed.
The axial dimension of the cylindrical spacer 11 to be sandwiched between the inner end surfaces (the end surfaces facing each other) of a and 8b is reduced. Then, the inner ring 8a, among both end faces of 8b, the distance D ₈ between the outer end surface opposite to each other, following 2.8 times the inner diameter R _8b of the inner ring 8b constituting the tapered roller bearing 3b of the outer side ( D ₈ ≦ 2.8R _8b ). As described above, the distance D ₈ between the outer end faces is set to the inner diameter R of the inner ring 8 b.
_The reason for setting the contact angles α and β of the two tapered roller bearings 3a and 3b within the above range is that the radial load and the axial load applied to the two tapered roller bearings 3a and 3b are reduced to 2.8 times or less. This is to reduce the size of the double-row tapered roller bearing device while balancing the load. The minimum value of the distance D ₈ between the outer end faces, the inner diameter R of the inner ring 8b
_About 1.5 times of _8b is required.

According to the double-row tapered roller bearing device of the present invention configured as described above, the inner-side tapered roller bearing 3a is provided.
, The radial rigidity of the tapered roller bearing 3a on the inner side can be sufficiently increased.
Therefore, regardless of the large radial load received from the pinion gear 4 fixed to the inner end of the pinion shaft 2 serving as the rotation shaft, the displacement of the pinion gear 4 in the radial direction is suppressed, and the pinion gear 4 and the other gears are formed. The meshing state with the ring gear 5 can be maintained in the normal state. Therefore, the transmission efficiency of the meshing portion between the pinion gear 4 and the ring gear 5 is ensured, and abnormal noise is generated at the meshing portion.
It is possible to prevent the wear of the meshing portion from becoming remarkable.

The inner side tapered roller bearing 3a
Is smaller than the contact angle α of the tapered roller bearing 3b on the outer side by 5 degrees or more, it is assumed that a radial load of the same magnitude acts on both the tapered roller bearings 3a and 3b. The axial load generated in the tapered roller bearing 3b on the outer side is larger than the axial load generated in the tapered roller bearing 3a on the inner side. However, in practice, the radial load acting on the inner tapered roller bearing 3a closer to the pinion gear 4 becomes larger than the radial load acting on the outer tapered roller bearing 3b far from the pinion gear 4.
Therefore, there is no large difference between the axial loads generated in the inner side, the outer side, and the inside of both the tapered roller bearings 3a and 3b. For this reason, even if the axial load generated inside each of these tapered roller bearings 3a and 3b is unbalanced, the size is small, and the amount of unbalance is sufficient by any of the tapered roller bearings 3a and 3b. Can be supported.

[0018]

Since the double-row tapered roller bearing device of the present invention is constructed and operates as described above, it is possible to reduce the size and weight while ensuring, for example, the durability and transmission efficiency of the differential gear. For this reason, it is possible to contribute to the improvement of the performance of various mechanical devices, for example, to improve the performance by reducing the weight of an automobile incorporating the differential gear.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a differential gear, showing an example of an embodiment of the present invention.

FIG. 2 shows only a pair of tapered roller bearings, and FIG.
Sectional drawing seen from the same direction.

FIG. 3 is a partial sectional view of a differential gear, showing one example of a conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gear case 2 Pinion shaft 3a, 3b Tapered roller bearing 4 Pinion gear 5 Ring gear 6a, 6b Outer ring 7a, 7b Outer ring track 8a, 8b Inner ring 9a, 9b Inner ring track 10 Tapered roller 11 spacer

Claims (2)

[Claims] 1. A first and a second tapered roller bearing in which the directions of the contact angles are opposite to each other, and the respective outer rings are internally fixed to a fixed portion, and the inner rings of the two tapered roller bearings are internally fixed. A rotating shaft rotatably supported by the fixed portion, and fixed to a portion protruding from the first tapered roller bearing to the opposite side of the second tapered roller bearing at one end of the rotating shaft. In the double-row tapered roller bearing device used in a state in which the set gear is engaged with another gear, the contact angle α of the second tapered roller bearing is set to be 5 times larger than the contact angle β of the first tapered roller bearing. Not less than
A double row wherein the interval between the outer end faces of the inner ring of the two tapered roller bearings opposite to each other is 2.8 times or less the inner diameter of the inner ring of the second tapered roller bearing. Tapered roller bearing device. 2. The contact angle α of the second tapered roller bearing is set to 34.
2. The double-row tapered roller bearing device according to claim 1, wherein the contact angle β of the first tapered roller bearing is 12 degrees or more.