JPH109258A - Bearing unit for supporting pinion shaft of differential gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of tapered roller bearing and a ball bearing to support a pinion shall while securing the lubricity of the bearings. SOLUTION: An outer circumferential edge of a second seal ring 26 is locked to an inner circumferential surface of a rear end part of an outer ring 6. An inner circumferential edge of a rubber seal lip to constitute the second seal ring 26 is brought into slidable contact with an outer circumferential surface of a pinion shaft 1 over the whole circumference. The lubricating oil stored in a casing 3 passes a slidably contact part of the inner circumferential edge of the seal lip with the outer circumferential surface of the pinion shaft 1, and enters a tapered roller bearing 12. Foreign matters such as abrasion powder mixed in the lubricating oil can not pass the slidably contact part, and are retained within the casing 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing unit for supporting a pinion shaft of a differential gear for rotatably supporting a pinion shaft constituting a differential gear (final reduction gear) of an automobile inside a casing (differential case). Regarding improvement.

[0002]

2. Description of the Related Art FIG. 3 shows a differential gear provided in the middle of a power transmission system of an automobile to reduce the rotation of a propeller shaft and convert the rotation direction to a right angle at the same time as disclosed in Japanese Patent Application Laid-Open No. Sho 53-74653. Such a structure is described. First, the conventional structure shown in FIG. 3 will be described. The front-back direction in the following description is FR
A description will be given of a case of a differential gear for a vehicle (a front-engine rear-wheel drive vehicle). In the case of a differential gear incorporated in a vehicle having a driving form other than an FR vehicle such as an FF vehicle (front-wheel drive vehicle with front engine), an RR vehicle (rear-wheel drive vehicle with rear engine), a midship engine vehicle, etc., the front-rear direction is not necessarily required. Not necessarily the same.

The front end (left end in FIG. 3) of the pinion shaft 1 disposed in the front-rear direction (left-right direction in FIG. 3) of the vehicle is formed by a connection flange 2 which is externally fitted and fixed to the front end of the pinion shaft 1. It can be connected to the rear end of a propeller shaft (not shown). A small reduction gear 4 is fixed to a portion of the rear end (the right end in FIG. 3) of the pinion shaft 1 which is located in the casing 3 containing the differential gear. The reduction gear 4 meshes with a reduction gear (not shown) rotatably supported in the casing 3.

The front wall of the casing 3 is provided with a cylindrical through-hole 5 for communicating the inside and the outside of the casing 3. Inside the through-hole 5, the pinion shaft 1 is supported so as to be rotatable only. I have. That is, a cylindrical outer ring 6 is screwed and fixed inside the through hole 5, and the pinion shaft 1 is fixed.
A pair of front and rear inner rings 7 and 8 are externally fitted and fixed. And
A plurality of tapered rollers 11 are provided between an outer raceway 9 formed on the inner peripheral surface of the rear end of the outer race 6 and an inner raceway 10 formed on the outer peripheral surface of the inner race 7 on the rear side.
Is composed. A plurality of balls 15, 15 are provided between an outer raceway 13 formed on the inner peripheral surface of the front end of the outer race 6 and an inner raceway 14 formed on the outer peripheral surface of the inner race 8 on the front side to form a ball bearing 16. ing. The pinion shaft 1 is rotatably supported on the casing 3 by the tapered roller bearings 12 and the ball bearings 16. Further, the outer ring 6
The outer peripheral edge of the seal ring 17 is engaged with the inner peripheral surface of the front end portion of the ball bearing 16.
Is slidably contacted with the surface of the inner ring 8 constituting.

During operation of the differential gear configured as described above, a large reduction gear (not shown) rotates with the rotation of the pinion shaft 1. The large reduction gear scrapes up the lubricating oil (differential oil) stored in the casing 3. As a result, splashes of lubricating oil enter the outer race 6 and lubricate the tapered roller bearings 12 and the ball bearings 16.

[0006]

In the lubricating oil that is scraped up by the reduction gears during the operation of the differential gear, wear powder and the like generated due to friction between the reduction gears and the reduction gear 4 are contained. Foreign matter has entered. Therefore, in the case of the conventional structure shown in FIG. 3, foreign matter is fed into the tapered roller bearing 12 and the ball bearing 16 together with the lubricating oil.

When such foreign matter is fed into the tapered roller bearing 12 and the ball bearing 16, the respective bearings 12, 16
And the rolling surfaces of the tapered rollers 11 and 11 and the balls 15 and 15, the outer raceways 9 and 13, and the inner raceways 10 and 14 may be damaged. That is, the foreign matter promotes the wear of the rolling surfaces and the raceways, causing the preload of the bearings 12 and 16 to be insufficient, that is, so-called preload loss, or noise increase during operation, It causes deterioration of durability due to generation of king. The bearing unit for supporting a pinion shaft of a differential gear of the present invention has been invented in view of such circumstances.

[0008]

The bearing unit for supporting a pinion shaft of a differential gear according to the present invention has one end connected to the end of a drive shaft, similarly to the above-mentioned conventional bearing unit for supporting a pinion shaft of a differential gear. Freely,
A pinion shaft on which the other end portion is fixed with a reduction gear that meshes with the reduction gear, and arranged around the pinion shaft and concentrically with the pinion shaft, and penetrating the side wall of the casing of the differential gear in an oil-tight manner. An outer ring fixed to the casing, two axially separated positions on the inner peripheral surface of the outer ring, and two axially separated positions at an intermediate portion of the pinion shaft.
A pair of rolling bearings provided between the pinion shaft and rotatably supporting two positions axially separated at an intermediate portion of the pinion shaft with respect to the casing; and an inner peripheral surface at one end of the outer ring. A seal ring is provided between the pinion shaft and an outer peripheral surface of an inner ring fixedly fitted to the pinion shaft to prevent the lubricating oil present in the casing from leaking to the outside. In the pinion shaft, a first rolling bearing rotatably supporting a side far from the reduction pinion is a ball bearing, and a second rolling similarly rotatably supporting a side close to the reduction pinion. The bearing is a tapered roller bearing. In particular, in the bearing unit for supporting the pinion shaft of the differential gear of the present invention,
A second seal ring is provided between the inner peripheral surface of the end portion of the outer ring located on the side of the reduction gear and the outer peripheral surface of the inner ring fixedly fitted to the intermediate reduction gear portion near the intermediate portion of the pinion shaft or this portion. Is provided. The second seal ring has one peripheral edge locked to one of the inner peripheral surface of the outer race and the outer peripheral surface of the pinion shaft or the inner race. The other peripheral portion of the second seal ring is made of rubber, and is slid over the entire peripheral surface of the inner peripheral surface of the outer ring and the other peripheral surface of the pinion shaft or the outer peripheral surface of the inner ring. I have.

[0009]

The bearing unit for supporting the pinion shaft of the differential gear according to the present invention configured as described above rotatably supports the pinion shaft, and reduces the rotation of the drive shaft via the pinion shaft and the reduction gear to reduce the speed. The operation at the time of transmission to the gear is the same as in the case of the conventional structure described above. In particular, in the case of the bearing unit for supporting a pinion shaft of a differential gear according to the present invention, foreign matters are contained in both the first and second rolling bearings while ensuring the lubricity of the ball bearing and the tapered roller bearing. It can be prevented from entering. That is, since lubricating oil is stored inside the lower part of the casing of the differential gear, the lower part of the sliding contact between the other peripheral surface and the other peripheral part of the second seal ring is formed by the lubricating oil. It will be immersed in oil. Further, the contact pressure between the other peripheral portion and the other peripheral surface in the sliding contact portion depends only on the elasticity of the rubber constituting the other peripheral portion of the second seal ring. Therefore, a part of the lubricating oil existing in the casing leaks toward the tapered roller bearing through the lower part of the sliding contact portion. As a result, the tapered roller bearing is sufficiently lubricated. On the other hand, the foreign matter mixed in the lubricating oil existing in the casing cannot pass through the sliding contact portion and stops in the casing. Therefore, the tapered roller bearing and the ball bearing are not damaged by the foreign matter mixed in the lubricating oil. Although the amount of lubricating oil reaching the ball bearing portion, which is the first rolling bearing, is smaller than the amount of lubricating oil reaching the tapered roller bearing, lubrication of the ball bearing does not become defective. That is, the ball bearing can perform sufficient lubrication with less lubricating oil than the tapered roller bearing. The initial lubrication may be performed by filling grease in the ball bearing.
Further, most of the thrust load applied to the pinion shaft based on the engagement of the reduction gear and the reduction gear during operation of the differential gear is received by the tapered roller bearing, and the thrust load transmitted to the ball bearing is extremely small. small. Therefore,
The ball bearing described above does not cause damage such as seizure if only a small amount of lubricating oil is supplied.

[0010]

FIG. 1 shows a first embodiment of the present invention. The front-back direction of the vehicle (left-right direction in FIG. 1)
At the front end (left end in FIG. 1) of the pinion shaft 1 disposed on the inside, a cylindrical portion 18 formed on the inner peripheral edge of the connection flange 2 is fitted to the outside by a tight fit. And the front end of the pinion shaft 1 are in serration engagement. In an assembled state to the automobile, the rear end of a propeller shaft (not shown) is connected to the connection flange 2 so that the pinion shaft 1 can be driven to rotate. A small reduction gear 4 is fixed to a portion of the rear end (the right end in FIG. 1) of the pinion shaft 1 located in the casing 3 containing the differential gear. This reduction small gear 4
Is engaged with a large reduction gear (not shown) rotatably supported in the casing 3.

The front wall of the casing 3 is provided with a cylindrical through hole 5 for communicating the inside and the outside of the casing 3, and the pinion shaft 1 is rotatably supported inside the through hole 5 only for rotation. I have. For this purpose, a cylindrical outer ring 6 is fixed inside the through hole 5. A mounting flange 19 is formed on the outer peripheral surface of the intermediate portion of the outer ring 6 over the entire circumference. The through hole 2 formed in the mounting flange 19
The outer ring 6 is supported and fixed inside the through hole 5 by screwing the bolts 21, 21 having the 0, 20 inserted therein into the screw holes 22, 22 formed in the casing 3 and further tightening them. An annular gasket is sandwiched between the one side surface (the right side surface in FIG. 1) of the mounting flange 19 and the front end surface (the left end surface in FIG. 1) of the casing 3 over the entire circumference. Lubricating oil is prevented from leaking from between the casing 3 and the outer ring 6.

A conical concave outer raceway 9 is formed near the rear end of the inner peripheral surface of the outer race 6, and an angular outer raceway 13 is formed near the front end. On the other hand, a conical convex inner raceway 10 is formed directly on the outer peripheral surface of the pinion shaft 1 in a portion near the rear end of the intermediate portion of the pinion shaft 1. A plurality of tapered rollers 11, 11 are provided between the inner raceway 10 and the outer raceway 9 to form a tapered roller bearing 12, which is a second rolling bearing.

On the other hand, a small diameter portion 23 is formed in the front half portion (left half portion in FIG. 1) of the pinion shaft 1, and the small diameter portion 23 and the rear half portion (right half portion in FIG. 1) are formed by a step portion 24. It is continuous. Then, the inner ring 8 is externally fitted to the small diameter portion 23, and the inner ring 8 is connected to the step portion 24 and the cylindrical portion 1 of the connection flange 2.
8 between. An angular inner raceway 14 is formed on the outer peripheral surface of the inner race 8, and a plurality of balls 15, 15 are provided between the inner raceway 14 and the outer raceway 13 to provide a ball bearing as a first rolling bearing. 16. The pinion shaft 1 is rotatably supported on the casing 3 by the tapered rollers 12 and the ball bearings 16.

An outer peripheral edge of a seal ring 17 is fitted and fixed on the inner peripheral surface of the front end of the outer ring 6.
The inner peripheral edge of the inner ring 7 is in sliding contact with the outer peripheral surface of the inner ring 8 constituting the ball bearing 16. In addition, a holding ring 25 is attached to the seal ring 17 to sufficiently increase the contact pressure between the inner peripheral edge of the seal ring 17 and the outer peripheral surface of the inner ring 8. Therefore, the leakage of the lubricating oil that has entered the inside of the outer ring 6 to the outside through the seal ring 17 can be prevented.
Can be sufficiently prevented.

Further, the outer peripheral edge of the second seal ring 26, which is one peripheral edge, is fitted over the entire inner periphery of the inner peripheral surface of the rear end portion of the outer ring 6 located on the side of the reduction small gear 4. Locked. The second seal ring 26 has an outer peripheral side portion made of a core metal and an inner peripheral side portion made of a rubber seal lip, and a distal end portion (inner peripheral edge portion) of the seal lip faces an opposite side in the axial direction. Divided into two parts. The inner peripheral portion of the seal lip, which is the other peripheral portion, is slidably contacted with the outer peripheral surface of the rear end portion of the pinion shaft 1 over the entire circumference.

The pinion shaft supporting bearing unit of the differential gear of the present invention configured as described above rotatably supports the pinion shaft 1, and controls the rotation of the drive shaft, which is the drive shaft, by the pinion shaft 1 and the reduction gear. The operation at the time of transmission to the large reduction gear via the gear 4 is the same as that of the above-described conventional structure.

In particular, in the case of the bearing unit for supporting the pinion shaft of the differential gear according to the present invention, the lubrication of the ball bearing 16 and the tapered roller bearing 12, which are the first and second rolling bearings, is ensured. Foreign matter can be prevented from entering the bearings 16 and 12. That is, since the lubricating oil is stored inside the lower part of the casing 3 of the differential gear, the sliding contact portion between the inner peripheral edge of the second seal ring 26 and the outer peripheral surface of the rear end of the pinion shaft 1 is formed. The lower part is immersed in the lubricating oil. Also, the inner peripheral edge of the second seal ring 26 and the pinion shaft 1
The contact pressure with the outer peripheral surface of the rear end portion depends only on the elasticity of the rubber constituting the inner peripheral edge of the second seal ring 26. Therefore, a part of the lubricating oil existing in the casing 3 permeates toward the tapered roller bearing 12 through the lower part of the sliding contact portion. That is, since the oil molecules are extremely small, if the inner peripheral edge of the seal lip constituting the second seal ring 26 and the outer peripheral surface of the pinion shaft 1 are rubbed against each other in a lightly contacting state, the lubrication inside the casing 3 will not occur. Oil seeps out to the tapered roller bearing 12 side to lubricate the tapered roller bearing 12. Since the tapered roller bearing 12 is provided at a position adjacent to the second seal ring 26, most of the oozed lubricating oil is taken into the tapered roller bearing 12, and the tapered roller bearing 12
Lubrication is performed effectively enough.

On the other hand, since the particle diameter of the foreign matter mixed in the lubricating oil existing in the casing 3 is much larger than that of the molecules of the lubricating oil, the particles cannot pass through the sliding contact portion. Instead, it stops in the casing 3. Therefore, the tapered roller bearing 12 and the ball bearing 16 are not damaged by foreign matters mixed in the lubricating oil.

The ball bearing 16 as the first rolling bearing
Is provided at a position distant from the second seal ring 26, the amount of lubricating oil reaching the ball bearing 16 is smaller than the amount of lubricating oil reaching the tapered roller bearing 12. However, the lubrication of the ball bearing 16 does not become defective for the following reasons. That is, the ball bearing 1
6 has a small contact area between the raceway surface and the rolling element, so that sufficient lubrication can be performed with less lubricating oil than the tapered roller bearing 12. Most of the thrust load applied to the pinion shaft 1 based on the engagement of the reduction gear 4 and the reduction gear during operation of the differential gear is received by the tapered roller bearing 12 having a large load capacity in the thrust direction. Therefore, the thrust load transmitted to the ball bearing 16 is extremely small. For this reason, the ball bearing 16 does not cause damage such as seizure if only a small amount of lubricating oil is supplied.

FIG. 2 shows a second embodiment of the present invention.
An example is shown. In the case of the first example described above, the inner ring raceway 10 constituting the tapered roller bearing 12 is formed directly on the outer peripheral surface of the pinion shaft 1, whereas in the case of the present example,
As in the case of the conventional structure shown in FIG. 3 described above, an inner race 7 having an inner raceway 10 formed on the outer peripheral surface thereof is fitted around the pinion shaft 1. In the case of the illustrated example, a cylindrical spacer 27 is provided between the inner ring 7 forming the tapered roller bearing 12 and the inner ring 8 forming the ball bearing 16. The spacing is maintained.

If the inner raceway 10 constituting the tapered roller bearing 12 is formed directly on the outer peripheral surface of the pinion shaft 1 as in the structure of the first example shown in FIG. Of the tapered roller bearing 12
And the preload management of the ball bearing 16 becomes easy. However, it is necessary to make the entire pinion shaft 1 from a material having hardness enough to form the inner raceway 10, such as bearing steel. On the other hand, in the case of the structure of the second example shown in FIG. 2, the preload management becomes complicated, but there is an advantage that it is not necessary to use expensive bearing steel as the pinion shaft 1.

Although not shown, the outer ring having a pair of outer ring raceways 9 and 13 on the inner peripheral surface can be divided into two parts at an intermediate portion in the axial direction. Further, in order to fix the outer ring 6 inside, a part of the through hole 5 formed in the housing 3 is recessed so that the outer peripheral surface of the outer ring 6 and the inner peripheral surface of the through hole 5 only partially contact. May be configured. By adopting such a structure, the weight of the housing 3 can be reduced.

[0023]

The bearing unit for supporting a pinion shaft of a differential gear according to the present invention is constructed and operates as described above, so that the noise generated in the portion supporting the pinion shaft during operation of the differential gear is suppressed, and furthermore, the noise is reduced. The durability of the part can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing a first example of an embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing the second example.

FIG. 3 is a vertical sectional side view showing one example of a conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pinion shaft 2 Connection flange 3 Casing 4 Reduction gear 5 Through hole 6 Outer ring 7, 8 Inner ring 9 Outer ring raceway 10 Inner ring raceway 11 Tapered roller 12 Tapered roller bearing 13 Outer ring raceway 14 Inner ring raceway 15 Ball 16 Ball bearing 17 Seal ring 18 Cylindrical Part 19 Mounting flange 20 Through hole 21 Bolt 22 Screw hole 23 Small diameter part 24 Step part 25 Suppression ring 26 Second seal ring 27 Spacer

Claims (1)

[Claims] An end of the drive shaft is freely connectable to an end of the drive shaft.
A pinion shaft on which the other end portion is fixed with a reduction gear that meshes with the reduction gear, and arranged around the pinion shaft and concentrically with the pinion shaft, and penetrating the side wall of the casing of the differential gear in an oil-tight manner. An outer ring fixed to the casing, two axially separated positions on the inner peripheral surface of the outer ring, and two axially separated positions at an intermediate portion of the pinion shaft.
A pair of rolling bearings provided between the pinion shaft and rotatably supporting two positions axially separated at an intermediate portion of the pinion shaft with respect to the casing; and an inner peripheral surface at one end of the outer ring. A seal ring provided between the pinion shaft or an outer peripheral surface of an inner ring fixedly fitted to the pinion shaft to prevent the lubricating oil present in the casing from leaking to the outside; Of the axes,
A first rolling bearing rotatably supporting a side far from the reduction pinion is a ball bearing, and a second rolling bearing rotatably supporting a side near the reduction pinion is a tapered roller bearing. In the bearing unit for supporting the pinion shaft of the gear, the inner peripheral surface of the end portion of the outer ring positioned on the side of the reduction pinion, and the portion of the pinion shaft near the reduction pinion of the reduction gear or the inner ring externally fixed to this portion. A second seal ring is provided between the outer ring and the outer ring, and the second seal ring has one of its peripheral portions on one of the inner circumferential surface of the outer ring and the outer circumferential surface of the pinion shaft or the inner ring. The other peripheral portion is made of rubber, and the other peripheral surface of the inner peripheral surface of the outer ring and the outer peripheral surface of the pinion shaft or the inner ring is slid over the entire periphery. Differential gear pini Down shaft supporting bearing unit.