JP2001248652A - Intermediate shaft bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate shaft bearing device capable of reducing an abnormal sound generated by waviness of raceway surfaces. SOLUTION: The radius of curvatures of recesses of raceway surfaces 2a, 3a in an inner ring and an outer ring 2, 3 of a bearing part in this intermediate shaft bearing device 1 is formed at 60% to 80% of the diameter of a ball 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate bearing device for supporting a rotating axle of a vehicle on a chassis at an intermediate portion.

[0002]

2. Description of the Related Art As shown in FIG. 6, a vehicle transmits a driving force from a transmission 13 to a speed reducer 14 by a plurality of axles 12 connected via a universal joint 11. However, it is difficult to transmit rotation smoothly only by connecting a plurality of axles 12 via the universal joint 11. Therefore, an intermediate portion of these axles 12 is supported by the chassis 15 via the intermediate bearing device 1. I have to.

As shown in FIG. 7, the intermediate bearing device 1 has a bearing portion in which a ball 4 is arranged so as to be able to roll between an inner ring 2 and an outer ring 3, and the inner periphery of the inner ring 2 of the bearing portion is provided. Externally fixed to the axle 12. The outer ring 3 has a case 7 on the outer periphery.
The bracket 8 is attached and fixed to the chassis 15. The axle 12 is supported on the chassis 15 by fixing the case 7 to the bracket 8 via an elastic body 6 made of rubber or resin. The seal 9 is for preventing dust and muddy water from entering the bearing portion of the intermediate bearing device 1 from the outside.

As shown in FIG. 8, a bearing portion of the intermediate bearing device 1 has a concave raceway surface 2 formed on an outer peripheral surface of an inner ring 2.
A plurality of balls 4 are held by a retainer 5 and arranged between a and a concave raceway surface 3 a formed on the inner peripheral surface of the outer ring 3. When the inner race 2 rotates with the axle 12 in a state where the outer race 3 is attached to the chassis 15 via the elastic body 6, the balls 4 roll on the raceway surfaces 2 a of the inner race 2 and the outer race 3. The bearing of the rotating axle 12 is performed by the movement.

[0005]

However, the above-mentioned conventional intermediate bearing device 1 may generate abnormal noise, particularly in a low-temperature environment, and may cause occupants of a vehicle to be concerned about malfunction. Had occurred. Further, in order to prevent such abnormal noise, conventionally, measures such as lowering the viscosity of grease sealed in the bearing portion of the intermediate bearing device 1 have been tried, but a sufficient solution has not been obtained.

The present invention has been made in order to cope with such circumstances, and the generation of abnormal noise is prevented by setting the radius of curvature of the raceway surface to a radius within a predetermined range that is sufficiently large with respect to the ball diameter. It is an object of the present invention to provide an intermediate bearing device that can perform the above-described operations.

[0007]

According to a first aspect of the present invention, there is provided an inner ring having an inner peripheral portion fixed to an axle, and a plurality of balls arranged on the outer peripheral side of the inner ring so as to be rollable. In an intermediate bearing device comprising an outer ring supported on a chassis via an elastic body, a radius of curvature of a concave cross section along an axial direction on a raceway surface of a ball formed on an outer peripheral surface of an inner ring and an inner peripheral surface of an outer ring. Is not less than 60% and not more than 80% of the ball diameter.

As a result of investigating the cause of the abnormal noise generated in the intermediate bearing device, it was found that the abnormal noise was mainly caused by the undulation of the raceway surfaces formed on the inner and outer rings of the bearing portion.
In addition, when such undulations were found, it became clear that the noise increased as the radius of curvature of the raceway approached the radius of the ball (50% of the ball diameter). However, if the radius of curvature of this raceway surface is too large, the outer ring may be displaced in the axial direction and come off the inner ring. Therefore, as described in the first aspect of the present invention, the generation of the abnormal noise can be sufficiently suppressed by setting the radius of curvature of the raceway surface within the range of 60 to 80% of the ball diameter.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the present invention. FIG. 1 is a partially enlarged longitudinal sectional view of a bearing portion of an intermediate bearing device, and FIG. 2 is a bearing portion showing undulation of a raceway surface. FIG. 3 is a longitudinal sectional view of the intermediate bearing device, FIG. 4 is a block diagram showing a model of a displacement motion generated in an outer ring of the intermediate bearing device, and FIG. 5 is a diagram showing a simulation result of generation of abnormal noise. is there. Components having the same functions as those of the conventional example shown in FIGS. 6 to 8 are denoted by the same reference numerals.

In this embodiment, an intermediate bearing device 1 having the same structure as the conventional example shown in FIG. 7 will be described. As shown in FIG. 1, a bearing portion of the intermediate bearing device 1 includes a raceway surface 2 a formed on the outer peripheral surface of the inner race 2 and having a concave cross section in the axial direction, and an outer race 3.
A plurality of balls 4 are arranged to be held by a retainer 5 between a raceway surface 3a having a concave cross section in the axial direction formed on the inner peripheral surface of the ball.

Here, in the conventional intermediate bearing device 1 shown in FIG. 7, the radius of curvature of the concave shape of the raceway surfaces 2a and 3a is, for example, 51% of the diameter of the ball 4 (ball diameter). Was formed to a small value very close to the radius of curvature of the peripheral surface. As a result of an investigation conducted by the inventor on such abnormal noise generated in the intermediate bearing device 1, as shown in FIG. 2, a raceway surface 2 formed on the inner ring 2 and the outer ring 3 of the intermediate bearing device 1 was obtained.
It has been found that the waviness formed in the axial direction parallel to the axis on the circumference of the circles a and 3a is the main cause of the abnormal noise.

That is, due to such undulation, the raceway surface 2
When a and 3a meander, the inner ring 2 and the outer ring 3 are brought into contact with the ball 4 with the rotation, and an axial rolling friction force substantially parallel to the axis, that is, the inner ring forced force _Fi and the outer ring forced force _Fo are generated. I do. Then, as shown in FIG. 3, the inner ring 2 and the outer ring 3
Axial forces are applied in opposite directions in the axial direction, and the inner ring 2 is
Since the position in the axial direction is fixed by 2, the outer ring 3
Will be displaced in the axial direction by this forcing force. The displacement movement of the outer ring 3 is caused by the raceway surfaces 2a, 3a
Therefore, the vibration is repeated according to the amplitude, the mass of the outer ring 3 to which the forcing force F is applied is m, the resistance due to sliding or the like is R, and the axial spring constant of the elastic body 6 is K _R. , can be represented by a model shown an axial spring constant of the bearing formed by the inner ring 2 and outer ring 3 and the balls 4 in FIG. 4, K _B, the displacement of the mass m of the outer ring 3 system x, Assuming that the time is t, the equation of motion as shown in Equation 1 is established.

(Equation 1) Then, the sound pressure generated by the elastic body 6 acting as a diaphragm due to the displacement x is propagated into the air and causes abnormal noise.

Further, the force F, as shown in Equation 2 is obtained by adding the sum of all the balls 4 of the inner ring forcing F _i and the outer ring force F _o.

(Equation 2) The inner ring forced force F _i and the outer ring forced force F _o are, as shown in Equation 3, the Young's modulus E, the density ρ and viscosity ν of the lubricating oil, the load Q of the ball 4, the inner ring rotation speed ω, and undulation amplitude W _a and the number of ridges n, coefficient H and various constants a, b, and the c parameter, these raceways 2a, a magnitude proportional to the equivalent radius of curvature G _R of 3a.

(Equation 3) Then, the equivalent radius of curvature G _R are each raceway surface 2
a, if the actual radius of curvature of 3a and G _r, the diameter of the ball 4 as D, represented by the number 4.

(Equation 4)The ball 4 needs to be fitted into the concave shape of the raceway surfaces 2a and 3a.
The radius of curvature G _rDoubled (2G_r)
It cannot be smaller than the diameter D of the ball 4. Toes
2G_r> D, radius of curvature G_rThe ball diameter
It must be greater than 50% of D.

Accordingly, the larger the radius of curvature G _r with respect to the ball diameter D, the smaller the equivalent radius of curvature G _R ,
The forcing force F is also reduced, and the noise pressure of abnormal noise can be reduced. Therefore, it is sufficient radius of curvature G _r sufficiently larger than 50% of the ball diameter D, a result of simulation,
It became clear that almost no noise was generated when the ratio was 60% or more. That is, if the radius of curvature of the raceway surfaces 2a, 3a increases, the balls 4 can be displaced to some extent on the raceway surfaces 2a, 3a in the axial direction, so that the inner ring forced force _Fi and the outer ring forced force shown in FIG. This is because _Fo also decreases and the displacement x of the outer ring 3 also decreases. However, the raceway surfaces 2a, 3a
If the radius of curvature G _r is excessively large, since it is impossible to stop the displacement in the axial direction of the ball 4, the radius of curvature G _r must be less than or equal to 80% of the ball diameter D.

Also, the natural frequency ω derived from Equation 1
₀ is obtained by Expression 5.

(Equation 5) Spring constant K _B of the axial bearing is provided between the curvature radius G _r as shown in Equation 6, since there is an inverse relationship in which the p and exponent, increasing the radius of curvature G _r, natural frequency ω
₀ becomes smaller.

(Equation 6)

[0017]

When the radius of curvature of the raceway surfaces 2a and 3a of the inner ring 2 and the outer ring 3 of the intermediate bearing device 1 is set to 51% of the diameter of the ball 4 as in the conventional case (conventional example C), 60% as the embodiment.
FIG. 5 shows the result of simulating the generation of abnormal noise for each rotation frequency of the inner ring 2 in the case of (Example A). At this time, the diameter of the ball 4 was set to 7.1435 mm, and the number of balls was calculated to be 11 pieces. The same conditions were used for other constants.

As a result, in the conventional example C, the rotation frequency is 3
It can be seen that a sound having a large peak is generated around 0 Hz. On the other hand, Example A in which the radius of curvature was 60%
In this example, only a sound having a sufficiently small peak at around 15 Hz was generated, and the effect of reducing the generation of abnormal noise became clear.

The radius of curvature of the raceway surfaces 2a, 3a is
70% (Example B), and the diameter of ball 4 was 6.35 mm and the number of balls was 9;
At around 0 Hz, only a sound having an extremely small peak of about 1/5 of the conventional example C was generated, and it was found that the generation of abnormal noise could be reliably prevented.

[0020]

As is apparent from the above description, according to the intermediate bearing device of the present invention, it is possible to reduce the generation of abnormal noise due to the undulation of the raceway surfaces of the inner ring and the outer ring of the bearing portion. Under the environment, it is possible to eliminate the fear that the generation of the abnormal noise may cause the occupant of the vehicle to feel uneasy.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a partially enlarged longitudinal sectional view of a bearing portion of an intermediate bearing device.

FIG. 2, showing one embodiment of the present invention, is a partially enlarged longitudinal sectional view of a bearing portion showing undulation of a raceway surface.

FIG. 3, showing one embodiment of the present invention, is a longitudinal sectional view of an intermediate bearing device.

FIG. 4 illustrates one embodiment of the present invention, and is a block diagram illustrating a model of a displacement motion generated in an outer ring of an intermediate bearing device.

FIG. 5 illustrates one embodiment of the present invention, and is a diagram illustrating simulation results of generation of abnormal noise.

FIG. 6 is a view showing an example of use of an intermediate bearing device for supporting an axle of an automobile.

FIG. 7 shows a conventional example and is a longitudinal sectional view of an intermediate bearing device.

FIG. 8 shows a conventional example, and is a partially enlarged longitudinal sectional view of a bearing portion of an intermediate bearing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intermediate bearing device 2 Inner ring 2a Track surface 3 Outer ring 3a Track surface 4 Ball 6 Elastic body 12 Axle 15 Chassis

Claims (1)

[Claims] 1. An inner ring having an inner peripheral portion fixed to an axle, and a plurality of balls arranged on the outer peripheral side of the inner ring so as to be able to roll, and the outer peripheral portion is supported by a chassis via an elastic body. In the intermediate bearing device composed of the outer ring, the radius of curvature of the concave section in the axial direction along the raceway surface of the ball formed on the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring is 60% of the ball diameter.
An intermediate bearing device characterized by being 80% or less as described above.