JPH09240209A - Pre-load applying structure for wheel bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a predetermined pre-load with high precision without using any separate spacer member so as to easily control application of a pre-load. SOLUTION: A stepped face 22 is formed in the predetermined position on the outer circumference of a spindle 3, while a wheel bearing (outer bearing) 4a is force fitted between a wheel hub 2 and the spindle 3 so that the outer race 8 is brought into contact with a stepped face 13 in the wheel hub 2, and at the same time, a spindle nut 12 is fastened in the spindle 3 while a clearance L5 with the predetermined interval is arranged between the inner race 9 and the stepped face 22 in the spindle 3. In this way, the inner race 9 is pressed and moved in the axial direction by the length of the clearance L5 by means of a fastening force of the spindle nut 12 so as to be brought into pressure contact with the stepped face 22 in the spindle 3, and in compliance with this, a pre-load is applied to the wheel bearing 4a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for applying a preload to a wheel bearing, which is formed by interposing a plurality of balls between an inner race and an outer race.

[0002]

2. Description of the Related Art FIG. 4 shows a wheel supporting portion (front suspension mechanism portion) of a conventional four-wheel vehicle equipped with a wheel bearing preloading structure. In FIG. 4, 1 is a driven front wheel. Reference numeral 2 denotes a wheel hub coaxially fixed to a central portion of the front wheel 1, 3 denotes a spindle (wheel shaft) fixed to the vehicle body side, and 4a and 4b are arranged between the wheel hub 2 and the spindle 3. Bearings for wheels, 5 is a suspension strut assembly, 6 is a suspension arm, and 7 is a tie rod for steering.

As shown in FIGS. 5 and 6, the pair of bearings 4a and 4b described above have a plurality of balls (between a cylindrical outer race 8 and an inner race 9 arranged coaxially with each other). Steel balls 10 are arranged in an aligned state along the circumferential direction, and are press-fitted between the wheel hub 2 and the spindle 3. Thus, these bearings 4a, 4b fulfill the function of rotating the front wheel 1 with respect to the spindle 3 while bearing the vertical force and lateral force from the road surface.

By the way, such bearings 4a, 4
When mounting b between the wheel hub 2 and the spindle 3, a preload is often applied in order to extend the life of the bearings 4a and 4b. Here, the preload application structure that has been conventionally adopted is described below. First, in FIG. 5, the spindle 3 has a spindle nut 1
2 (see FIGS. 4 and 6) before being tightened, showing the outer race 8 of each bearing 4a, 4b.
Is press-fitted into the inner peripheral portion of the wheel hub 2 and the step surface 1 of the wheel hub 2 is
Spacers 15 are disposed between the inner races 9 of the bearings 4a and 4b while abutting on the spacers 3 and 14, respectively. Under this condition, the gap between the end surface of the spacer 15 and the end surface of one inner race 9 is adjusted by appropriately adjusting the distance L ₁ between the step surfaces 13 and 14 and the length L ₂ of the spacer 15. L ₃ is to set (see FIG. 5).

FIG. 6 shows a state in which the spindle nut 12 is fastened to the spindle 3 for mounting the front wheel 1. In this case, the inner race 9 of the bearing 4a arranged on the spindle nut 12 side is shown. Receives a tightening force (pressing force) in the axial direction from the washer 16 as the spindle nut 12 is tightened, so that the bearing 4 a is locked relative to the outer race 8 of the bearing 4 a locked by the step surface 13 of the wheel hub 2. The inner race 9 in the axial direction (Fig. 6
In the direction of arrow A). And
When the inner race 9 of the bearing 4a is moved by the gap L _3, bearings 4a, 4b inner race 9
Of the inner race 9 of the other bearing 4b while the end faces of the bearing 15 are clamped to both end faces of the spacer 15.
Is pressed against the step surface 17 of the spindle 3.
In response to this, a preload of a gap L ₃ is applied between the outer race 8 and the inner race 9 of each bearing 4a, 4b, and this preload causes the outer race 8 and the inner race 9 to come into strong contact with the ball 10. There are two contact points P,
The straight line that occurs at Q and connects these contact points is shown in Fig. 6.
It has a contact angle α as shown in. The intersections R ₁ and R ₂ between these straight lines and the axis of the spindle are called operating points. By laying out these operating points R ₁ and R ₂ outside the positions where the bearings 4a and 4b are arranged, respectively. (See FIG. 6), the lives of the bearings 4a and 4b are extended.

[0006]

However, in the conventional preloading structure for a wheel bearing as described above, there are various problems as below. That is,
Since it is necessary to use the spacer 15 which is a separate member for the preload control of the bearings 4a and 4b, and the length L ₂ of the spacer 15 must be accurately manufactured in order to give a predetermined preload, In manufacturing, there is a problem that a polishing step is required and the cost becomes high. Further, when the spindle nut 12 is tightened, the spacer 15 is bent due to the tightening force, which makes it difficult to set the preload as designed and causes variations in the preload.

The present invention has been made to solve such a problem, and an object thereof is to apply a predetermined preload with high accuracy without using a spacer as a separate member. It is an object of the present invention to provide a preloading structure for a wheel bearing having a structure that enables easy preload management.

[0008]

To achieve the above object, in the present invention, a wheel bearing formed by interposing a plurality of balls between an inner race and an outer race is used as an inner peripheral surface of a wheel hub. A preload is applied to the wheel bearing, which is arranged between the outer peripheral surface of the spindle and the inner race and the outer race which are displaced from each other in the axial direction so as to preload the wheel bearing. In the structure, a step surface is formed at an outer peripheral portion on the end portion side of the spindle to which the spindle nut is tightened, and at a position spaced a predetermined distance from the step surface formed on the inner periphery of the wheel hub, The wheel bearing is press-fitted between the wheel hub and the spindle to bring the outer race into contact with the step surface of the wheel hub, and By tightening the spindle nut on the spindle under a state in which a gap having a predetermined interval is present between the inner race and the stepped surface of the spindle, the inner race is tightened by the tightening force of the spindle nut. The inner race is pressed and moved in the axial direction by an amount corresponding to the gap to press the inner race against the stepped surface of the spindle, and in accordance therewith, a preload is applied to the wheel bearing.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. 1 to 3, the same members as those in FIGS. 4 to 6 are designated by the same reference numerals.

FIG. 1 shows a front suspension mechanism portion provided with a preloading structure for a wheel bearing according to the present invention. In this example, a spacer which is a separate member which has been conventionally used is used. Instead, the outer bearing 4a and the inner bearing 4b are each provided with a required preload. Specifically, as clearly shown in FIG. 2 and FIG. 3, a coaxial small diameter shaft portion 20 and a large diameter shaft portion 21 having different diameters are provided at the end portion of the spindle 3, and a step surface 22 is provided therebetween. Is formed, and a step surface 23 is also formed at an outer peripheral portion separated from the step surface 22 by a predetermined distance L ₄ . On the other hand, on the inner peripheral portion of the wheel hub 2, a pair of step surfaces 1 are provided at predetermined positions as in the conventional case.
3 and 14 are formed. The predetermined distance L
₄ is an end surface of the inner race 9a of the outer bearing 4a and a step surface of the spindle 3 before tightening the spindle nut 12 when the outer bearing 4a and the inner bearing 4b are press-fitted onto the spindle 3 to be assembled as described later. 22 and a predetermined gap L ₅ (see FIG. 2)
Is set to exist.

Thus, in assembling the outer bearing 4a and the inner bearing 4b, the outer bearing 4a and the inner bearing 4b are first press-fitted inside the wheel hub 2 so that the end faces of the outer races 8 are formed on the step surface of the wheel hub 2. The outer bearing 4a and the inner bearing 4b are installed in the wheel hub 2 in such a manner that they are in contact with the wheel hub 13 and the wheel 14, respectively. Then, the inner bearing 4b incorporated in the wheel hub 2 is press-fitted onto the outer circumference of the large-diameter shaft portion 21 of the spindle 3 so that the end surface of the inner race 9 is attached to the spindle 3
The stepped surface 23 is pressed and positioned (see FIG. 2). Along with this, the inner race 9 of the inner bearing 4b is fitted onto the outer circumference of the small-diameter shaft portion 20 of the spindle 3, and the end surface of the inner race 9 has a gap L with respect to the step surface 22 of the spindle 3 as shown in FIG. It is placed at a position separated by ₅ .

When the spindle nut 12 is tightened under such a condition, the tightening force of the spindle nut 12 acts on the inner race 9 of the outer bearing 4a via the washer 16, so that the inner race 9
a is pushed and moved along the axial direction (direction of arrow A in FIG. 2) with respect to the outer race 8 in the fixed state. Then, the inner race 9 described above is connected to the spindle 3
The spindle nut 12 is tightened until it comes into contact with the step surface 20 of FIG.

As a result, the outer bearing 4a and the inner bearing 4b are interposed between the wheel hub 2 and the spindle 3 in a press-fitted state with a preload applied. In the case of this example, the outer bearing 4a and the inner bearing 4b are preloaded with contact angles α and β (usually α = β) as shown in FIG. 3, and the action point R ₁ of the outer bearing 4a is the spindle. It exists on the side of the nut 12, and the action point R ₂ of the inner bearing 4b is set so as to exist on the side opposite to the spindle nut 12.

According to the structure of this example, the outer bearing
The inner race 9 of 4a and the step surface 22 of the spindle 3
A gap L between the_FiveSet this inlay
Spindle nut 1 until the screw 9 hits the step surface 22.
By tightening 2, the outer bearing 4a and
Preload can be applied to the inner bearing 4b
You. In the case of such a structure, the step surface 22 of the spindle,
Distance between 23 (length) L _FourHas good accuracy with simple machining
This distance L_FourCan be set appropriately
With, it is possible to accurately set the preload level.
is there. Therefore, adjusting the tightening force of the spindle nut 12
Tightening the spindle nut 12 instead of preload control by adjustment
Make sure to set the optimum preload with high accuracy during the mounting work.
And the outer bearing 4a and
It is possible to extend the life of the inner bearing 4b.
You.

As described above, one embodiment of the present invention has been described.
The present invention is not limited to this embodiment, and various modifications and changes can be made based on the technical idea of the present invention. For example, the present invention can be applied to a case where only one wheel bearing is arranged between the spindle and the wheel hub.

[0016]

As described above, according to the present invention, the inner race of the wheel bearing is arranged with a predetermined gap from the step surface formed at a predetermined position on the outer circumference of the spindle, and the spindle nut is tightened to the spindle. The inner race is pressed against the outer race in a fixed state and brought into contact with the stepped surface to apply a preload to the bearing for the wheel. Therefore, the number of parts and the number of vehicle assembling steps can be reduced, and the cost can be reduced.

Further, since there is no deflection of the spacer which has been conventionally generated when the spindle nut is tightened, it is possible to easily manage the preload of the wheel bearing and to set the preload with high accuracy.

Further, since the spindle dimensional accuracy can be set with high accuracy by simple machining, rather than the spacer length accuracy, the accuracy of preload management itself can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a front suspension mechanism section including a wheel bearing preload applying structure according to the present invention.

FIG. 2 is a cross-sectional view showing an enlarged main part of the front suspension mechanism unit of FIG. 1, showing a state before tightening a spindle nut.

FIG. 3 is an enlarged cross-sectional view of a main part of the front suspension mechanism unit of FIG. 1, showing a state after tightening a spindle nut.

FIG. 4 is a cross-sectional view of a front suspension mechanism portion including a conventional wheel bearing preloading structure.

5 is an enlarged cross-sectional view of a main part of the front suspension mechanism portion of FIG. 4, showing a state before tightening the spindle nut.

6 is an enlarged cross-sectional view of a main part of the front suspension mechanism portion of FIG. 4, showing a state after tightening a spindle nut.

[Explanation of symbols]

1 front wheel (driven wheel) 2 wheel hub 3 spindle (wheel shaft) 4a outer bearing 4b inner bearing 8a, 8b outer race 9a, 9b inner race 10 ball (steel ball) 12 spindle nut 13, 14 step surface 22, 23 step surface R ₁ , R ₂ points of action

Claims (1)

[Claims] 1. A bearing for a wheel having a plurality of balls interposed between an inner race and an outer race is provided between an inner peripheral surface of a wheel hub and an outer peripheral surface of a spindle, and the inner race and In a preloading structure for a wheel bearing, in which a preload is applied to the wheel bearing by causing axial displacement with respect to the outer race, an outer peripheral portion on the end side of the spindle where a spindle nut is tightened And a stepped surface is formed at a position spaced a predetermined distance from the stepped surface formed on the inner periphery of the wheel hub, and the wheel bearing is press-fitted between the wheel hub and the spindle. The outer race against the stepped surface of the wheel hub and a predetermined distance between the inner race and the stepped surface of the spindle. By tightening the spindle nut on the spindle under the condition that the gap is present, the inner race is pressed and moved in the axial direction by the amount of the gap by the tightening force of the spindle nut. Is configured to be pressure-bonded to the stepped surface of the spindle and to apply a preload to the wheel bearing in accordance with the pressure.