JPH109259A - Bearing unit for supporting pinion shaft of differential gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost, and to improve the performance by facilitating the control of the pre-load of a tapered roller bearing and a ball bearing. SOLUTION: A pinion shaft 1 is rotatably supported by a tapered roller bearing 12 and a ball bearing 16 on the inner side of an outer ring 6 fixed to a casing 3. An inner ring raceway 10 to constitute the tapered roller bearing 12 is formed directly on an outer circumferential surface of the pinion shaft 1. Because the dimensional errors of components and the assembly errors are not integrated, the pre-load of the tapered roller bearing 12 and the ball bearing 16 can be easily controlled.

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 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 is disclosed in, for example, JP-A-53-74653. Such a structure is described. First, the conventional structure shown in FIG. 2 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.

A front end (left end in FIG. 2) of a pinion shaft 1 disposed in the front-rear direction (left-right direction in FIG. 2) of the vehicle is connected to 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 reduction gear 4 is fixedly provided at the rear end of the pinion shaft 1 (the right end in FIG. 2) 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 case of the conventional structure shown in FIG. 2, it is difficult to control the preload of the tapered roller bearing 12 and the ball bearing 16 for rotatably supporting the pinion shaft 1.
That is, in the case of the above-described conventional structure, the inner rings 7 and 8 are independent from each other, and these inner rings 7 and 8 are externally fixed to the pinion shaft 1 respectively. The tightening force of the nut 28 for fixing the connection flange 2 to the front end of the pinion shaft 1 is adjusted to regulate the force for pressing the pair of inner rings 7 and 8 in the axial direction. , 16 are managed.

When the preload of each of the bearings 12 and 16 is controlled with such a structure, an accurate preload is obtained by accumulating the dimensional errors and the assembly errors of the inner rings 7 and 8, the pinion shaft 1 and the connection flange 2. It becomes difficult to manage. 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,
The inner raceway constituting the tapered roller bearing is formed directly on the outer peripheral surface of the pinion shaft.

[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 the pinion shaft of the differential gear of the present invention, since the inner ring raceway of the tapered roller bearing is formed directly on the outer peripheral surface of the pinion shaft, the number of components is reduced, and the components are reduced when the preload is applied. Is difficult to accumulate. As a result, the required preload can be applied without extremely increasing the dimensional accuracy and the assembling accuracy of the component parts.

[0010]

FIG. 1 shows a first embodiment of the present invention.
An example is shown. The front end (left end in FIG. 1) of the pinion shaft 1 disposed in the front-rear direction (left-right direction in FIG. 1) of the vehicle includes:
The cylindrical portion 18 formed on the inner peripheral edge of the connection flange 2 is fitted to the outer periphery by interference fit, and the inner peripheral surface of the cylindrical portion 18 and the front end of the pinion shaft 1 are serrated. In the state of being assembled to an automobile, the connection flange 2
Is connected to a rear end of a propeller shaft (not shown) 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. 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, 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. That is, the inner ring 8 is pressed against the step portion 24 by pushing the cylindrical portion 18 into the front end portion of the pinion shaft 1 with a predetermined force by interference fit. 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 above pinion shaft 1
Are rotatably supported on the casing 3 by the tapered rollers 12 and the ball bearings 16. A predetermined preload is applied to the bearings 12 and 16 by pressing the inner ring 8 against the step portion 24 by the cylindrical portion 18.

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, a second seal ring 26 is provided on the inner peripheral surface of the rear end of the outer ring 6 located on the side of the reduction small gear 4.
Are fitted and locked over the entire circumference. 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 edge of the seal lip is in sliding contact with the outer peripheral surface of the rear end 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 a pinion shaft of a differential gear according to the present invention, the inner raceway 10 constituting the tapered roller bearing 12 is formed directly on the outer peripheral surface of the pinion shaft 1. The number of components is reduced, and it becomes difficult to add up the dimensional errors of the components at the time of applying the preload. As a result, the required preload can be applied without extremely increasing the dimensional accuracy and the assembling accuracy of the component parts.

In the case of the illustrated example, foreign matter enters the bearings 16 and 12 while ensuring the lubricity of the ball bearing 16 and the tapered roller bearing 12 as the first and second rolling bearings. Things can be prevented. 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. The contact pressure 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 at the sliding contact portion constitutes the inner peripheral edge of the second seal ring 26. Only due to rubber elasticity. 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 the molecule of the lubricating oil, the foreign matter 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 which is 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.

[0021]

As described above, the bearing unit for supporting the pinion shaft of the differential gear according to the present invention is constructed and operates as described above, so that the preload management is facilitated, the labor for applying the appropriate preload is reduced, and the cost is reduced. Can be achieved. In addition, effects such as lowering noise and improving durability can be obtained by applying an accurate preload.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal 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 track 10 Inner ring track 11 Tapered roller 12 Tapered roller bearing 13 Outer ring track 14 Inner ring track 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 28 Nut

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 differential in which 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 close to the reduction pinion is a tapered roller bearing. A bearing unit for supporting a pinion shaft of a differential gear, wherein an inner raceway constituting the tapered roller bearing is formed directly on an outer peripheral surface of the pinion shaft.