JPH06307438A - Wheel bearing - Google Patents

Abstract

PURPOSE:To set a space after assembly to an optimal value, and improve rigidity of a bearing while maintaining the rotating life of the bearing by forming a rotating surface opposing to the rotating surface of an outer wheel on the outer diameter of each inner wheel, and forming a prescribed space between small end surfaces of a pair of inner wheels which are formed with their back surfaces facing each other. CONSTITUTION:A space 6 corresponding to a prescribed axial direction space is formed between the small end surfaces 8a of a pair of inner wheels. A pair of inner wheels 8 is fastened till the volume of the space delta becomes 0, namely, till fastening torque is increased rapidly, by means of pressure-in of the inner wheels and fastening of a fixed nut, and a pre-load of a bearing is set. Initial space of the bearing has a relative relation with back pressure of air discharged from the space 6, and the back pressure is measured so as to manage negative space with good accuracy. It is thus possible to improve rigidity of a wheel bearing and reduce the level of vibration on a hub surface even if a large moment load is applied. And also it is possible to improve rigidity of the bearing while maintaining the rotating life of the bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bearings used for wheels of automobiles and the like.

[0002]

2. Description of the Related Art As shown in FIG. 2, a wheel (not shown) mounting flange (2) is integrally provided around the outer periphery of a hub (1) corresponding to a bearing outer ring, and a hub bolt (3) is fixed. Has been done. A double row ball rolling surface (6) is formed on the inner diameter (5) of the cylindrical portion (4) of the hub (1). On the other hand, the outer diameters of the pair of inner rings (8) fixed by press-fitting or inserting into the spindle (7) fixed to the vehicle body are respectively opposed to the ball rolling surface (6) and the ball rolling surface (9). ) Has been formed. The hub (1) is rotatably supported by the spindle (7) by the double rows of balls (10) interposed between the two rolling surfaces (6, 9). The inner ring (8) is sandwiched between the shoulder (11) of the spindle (7) and the fixed nut (12), but the bearing has an axial clearance.

In this type of bearing, it is advantageous to use the bearing with a negative axial clearance, that is, to apply a predetermined preload, from the viewpoints of rolling life and bearing rigidity of the bearing, but from the viewpoint of clearance management, Since it is difficult to measure the negative clearance, the initial clearance of the bearing is set in anticipation of a decrease in clearance by inserting or inserting the inner ring (8) into the spindle (7) and tightening of the nut (12). It was

[0004]

In the conventional bearing, even if the optimum amount of preload is calculated in terms of life and rigidity, there is no means for realizing it, and the initial clearance of the bearing is set to near 0. I couldn't find a way to do it. Further, the hub (outer ring) (1) is integrally formed with the rolling surface (6), and the outer ring is not press-fitted into the housing or the like unlike a normal bearing. However, even if the clearance reduction (3 to 40 μm) due to the above-mentioned bearing assembly is expected, the optimum preload amount could not be obtained.

Further, in order to make the skimmer after the bearing is incorporated negative, the range of the upper limit must be made as small as possible, with 0 being the measurable initial skimmer, and the range of the upper limit must be made as small as possible. There was a management problem.

[0006]

SUMMARY OF THE INVENTION A bearing for a wheel according to the present invention has an outer ring in which a flange is integrally provided on the outer periphery, and a double row rolling surface is formed on the inner diameter of a cylindrical portion, and the outer diameter of each inner ring. A pair of inner rings having a rolling surface opposite to the rolling surface of the outer ring formed on the rear surface, and the outer ring rotatably supported by being interposed between the outer ring rolling surface and the inner ring rolling surface. And a predetermined gap is formed between the small end faces of the pair of inner rings.

[0007]

By setting the clearance (δ) to a value corresponding to the desired axial clearance, optimum preload can be obtained by tightening the pair of inner rings (8) until the clearance (δ) becomes 0 during assembly. . In this way, by guaranteeing the initial clearance of the bearing with a negative clearance, the clearance after assembling can be set to an optimum value, and the bearing rigidity can be improved while maintaining the rolling life of the bearing.

[0008]

Embodiment An embodiment of the present invention will be described with reference to FIG. It should be noted that the same parts as those of the above-described conventional technique shown in FIG.

FIG. 1 shows the bearing before assembly, and a gap (δ) corresponding to a desired axial clearance is formed between the small end faces (8a) of the pair of inner rings (8). Inner ring (8)
By press-fitting and tightening the fixing nut (12) (Fig. 1), until the clearance (δ) becomes 0, that is, the tightening torque increases rapidly, the pair of inner rings (8)
Tighten to set the bearing preload. The initial clearance of the bearing has a correlation with the back pressure of the air discharged from the clearance (δ), and the negative clearance can be accurately controlled by measuring the back pressure. As a method of measuring the clearance (δ),
For example, the method previously proposed by the present applicant in Japanese Patent Application No. 3-57787 can be adopted.

FIG. 3 shows the rolling life (calculated value) of the bearing with respect to the amount of preload. In this case, the inner bearing is lower than the outer bearing, and gradually decreases at the preload amount B as a boundary. on the other hand,
The outer bearing gradually decreases from zero. As can be seen from this figure, the life of the entire bearing is dominated by the life of the inner bearing up to the preload amount B, and tends to decrease in proportion to the preload amount beyond that.

FIG. 4 is an actual measurement value comparing the rigidity of the bearing (the present invention) in which the amount of preload is set to the value shown by B in FIG. 3 and the conventional bearing in which a slight amount of preload (less than B) is applied. . In this case, the rigidity of the bearing is increased by about 25% by increasing the preload amount, and there is no initial low rigidity. This type of wheel bearing has a unique effect in that the rigidity of the flange surface is increased even with respect to the moment load from the wheel due to the turning of the vehicle, and the problem of braking performance is reduced. Also, it can be seen that the rolling life can be maintained without being reduced as compared with the conventional bearing.

In the double-row angular contact ball bearing as in the embodiment, the absolute value of the starting torque of the bearing is smaller than that of other bearings such as the double-row tapered roller bearing, and it is difficult to guarantee the clearance due to the correlation between the torque and the clearance. Therefore, in this type of bearing, which cannot be expected to reduce the clearance by press fitting the outer ring,
The possibility of guaranteeing negative clearance will have a remarkable effect.

Further, when the small end face (8a) of the inner ring (8) abuts, that is, when the absolute torque sharply rises, without strictly controlling the tightening torque of the fixing nut as in the conventional bearing. All you have to do is to finish tightening with, and workability in assembling can be improved.

The present invention is applicable not only to the outer ring rotating type non-driving side wheel bearing but also to the inner ring rotating type or drive side wheel bearing. The bearing is not limited to the double-row angular contact ball bearing, and may be a double-row tapered roller bearing.

[0015]

With the above construction, the present invention has the following effects.

The rigidity of the wheel bearing is increased, and the runout of the hub surface is reduced even when a large moment load is applied,
The swing of the brake rotor can also be reduced.

The rigidity of the bearing can be increased while maintaining the rolling life of the bearing.

The range of the initial clearance of the bearing can be increased and the defect rate can be reduced.

The workability of assembling the bearing can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a wheel bearing before assembly showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view of the wheel bearing in an assembled state.

FIG. 3 is a graph chart in which the total mileage life is plotted against the preload amount.

FIG. 4 is a graph diagram in which the bearing inclination angle is plotted against the moment load.

[Explanation of symbols]

 1 hub (outer ring) 2 flange 4 cylindrical part 5 inner diameter 6 rolling surface 8 inner ring 8a small end surface 9 rolling surface 10 ball (rolling element) δ gap

Claims (2)

[Claims] 1. An outer ring having a flange integrally provided on the outer periphery thereof, and a double row rolling surface formed on the inner diameter of the cylindrical portion, and rolling that opposes the rolling surface of the outer ring on the outer diameter of each inner ring. A pair of inner rings whose surfaces are formed and which are back-to-back and a double row rolling element interposed between the rolling surface of the outer ring and the rolling surface of the inner ring to rotatably support the outer ring, A wheel bearing in which a predetermined clearance is formed between the small end faces of a pair of inner rings. 2. The wheel bearing according to claim 1, wherein the bearing type is a double-row angular contact ball bearing.