JPH07174140A - Face-to-face combined angular ball bearing - Google Patents

Abstract

PURPOSE:To prevent a clearance from being generated in a bearing due to thermal expansion in an outer ring side while highly holding rigidity, in a face- to-face combined angular ball bearing. CONSTITUTION:A spacer 6 formed of a shape memory alloy is provided in an outer ring holding part 7 of a face-to-face combined angular ball bearing. The spacer 6 has a shape change characteristic such as extending by itself in an axial direction so as to compensate an axial direction thermal expansion component of a bearing supporter 9, when a temperature rises. In an environment of use with a small change of temperature in an inner ring side by generating a temperature rise in an outer ring side, when an outer ring space tends to spread by thermal expansion of the bearing supporter 9, since the spacer 6 is extended in the axial direction to cancel the thermal expansion component, a clearance in the axial direction is prevented from being generated, to hold a pre-load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front combined angular contact ball bearing, and more particularly to a front combined angular contact ball bearing used in vacuum.

[0002]

2. Description of the Related Art Conventionally, there are (1) a constant position preloading type and (2) a constant pressure preloading type as a method of applying a preload between an inner ring and an outer ring of an angular ball bearing. Examples of the front combination type are shown in FIGS. 2 and 3, respectively.

In the fixed position preload type, as shown in FIG. 2, the outer ring 1a is fixed and a preload between the inner ring and the outer ring is given by screwing a nut 5 into a bearing support 9 and tightening it.

The constant pressure preload type is, as shown in FIG. 3, an outer ring 1
A spring 8 inserted between a and the nut 5 holds the outer ring 1a and applies a preload between the inner ring and the outer ring.

[0005]

The above-mentioned conventional front face combination type angular contact ball bearing has the following problems in both the constant position preload system and the constant pressure preload system.

In the fixed position preload type, when the ambient temperature changes, the temperature on the bearing support 9 side rises accordingly, but the rotary shaft 4
When used in an environment where the temperature change on the side is small (for example, in a vacuum without convection), an axial gap is generated between the inner ring and the outer ring due to the difference in thermal expansion between the bearing support 9 and the rotating shaft 4.
Therefore, the rotation of the bearing causes rattling or vibration, which causes a significant deterioration in the function or damage of the bearing.

In the constant pressure preload type, the pressing force of the spring 8 holding the outer ring a suppresses the generation of the axial gap due to the thermal expansion described in the fixed position preload method, but the structure uses the spring. Therefore, the rigidity cannot be increased. Therefore, it is not suitable for high speed rotation.

An object of the present invention is to provide a front combined angular contact ball bearing with high rigidity used in an environment where the temperature on the outer ring side (bearing support) changes but the temperature change on the inner ring side (rotating shaft) is small. The object is to provide a front combined angular ball bearing that compensates for thermal expansion on the outer ring side and suppresses the generation of an axial clearance between the inner ring and the outer ring while maintaining the above.

[0009]

The front combination type angular ball bearing of the present invention is provided with a spacer made of a shape memory alloy in the outer ring holding portion thereof. That is, one outer ring is fastened and fixed with a nut via this spacer. When the ambient temperature rises, this spacer has a shape change characteristic (temperature change) which expands in the axial direction by itself so as to compensate the axial thermal expansion of the bearing support (that is, the outer ring spacing does not change). / Extension amount characteristic). This amount of elongation can be determined in advance from temperature conditions in the environment in which the bearing is used (temperatures of the bearing support and the rotating shaft with respect to ambient temperature), thermal expansion coefficients of the bearing support and the rotating shaft, and the like. This is the simplest case where the thermal expansion of the rotating shaft can be ignored, and the amount of expansion required for the spacer with respect to a certain temperature change is approximated by the amount of thermal expansion of the bearing support in the part corresponding to the two outer ring intervals. To be done.

[0010]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a front combination type angular contact ball bearing according to an embodiment of the present invention in the direction of the rotation axis. Here, two sets of angular contact ball bearings, which are an outer ring 1, an inner ring 2 and balls 3, are used to form a front combined type. The preload between the inner ring and the outer ring is obtained by the nut 5 screwed into the bearing support 9 pressing the outer ring a through the spacer 6 made of shape memory alloy.

Now, assuming that the temperature of the bearing support 9 rises by ΔT _{1 and} the temperature rise of the rotary shaft 4 can be ignored, the position D of the nut 5 shown in FIG. 1 is D + due to thermal expansion of the bearing support.
Extends to ΔD ₁ . This acts to create an axial clearance in the bearing. However, at the same time, the spacer 6 made of the shape memory alloy pushes the outer ring a by stretching ΔD _{1 in the} axial direction due to the shape change characteristic given in advance. Therefore, the distance between the outer ring a and the outer ring b is kept unchanged,
No axial gap is created.

On the other hand, when the temperature of the bearing support 9 is decreased by ΔT2 (the temperature change of the rotary shaft 4 can be ignored), the heat contraction of the bearing support 9 in the axial direction causes the nut 5 to move. The position D is shortened to D-ΔD2 and acts so as to cause an excessive load between the outer ring, the balls and the inner ring. At the same time, however, the spacer 6 contracts by .DELTA.D2 in the axial direction according to its shape change characteristic, so that the outer ring spacing is kept unchanged and no excessive load is generated in the bearing.

[0013]

As described above, according to the present invention, a spacer of shape memory alloy is added to the outer ring holding portion of the front combination type angular contact ball bearing, and the shape change characteristic is utilized to make the bearing support (outer ring side ), It is possible to compensate for the dimensional change due to thermal expansion.
It is possible to avoid deterioration of the function of the bearing, and it is possible to maintain high rigidity because a spring is not used.
Therefore, the present invention is suitable for use in a space vacuum environment in which the change in ambient temperature does not easily affect the rotating shaft.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of a fixed position preload type prior art example.

FIG. 3 is a sectional view of a prior art example of a constant pressure preload type.

[Explanation of symbols]

 1a Outer ring a 1b Outer ring b 2a Inner ring a 2b Inner ring b 3 Ball (rolling element) 4 Rotating shaft 5 Nut 6 Spacer 7 Outer ring holding part 8 Spring 9 Bearing support

Claims (2)

[Claims] 1. A front combination type angular contact ball bearing in which a front face combination type angular contact ball bearing is provided with a shape memory alloy spacer in an outer ring holding portion which applies a preload between the inner ring and the outer ring and holds the outer ring. . 2. A bearing support, an outer ring provided on an inner wall of the bearing support, a rotating shaft arranged inside the bearing support, an inner ring supporting the rotating shaft, and an outer ring and an inner ring. A front surface comprising a ball and an outer ring holding portion for holding the outer ring in the bearing support, the outer ring holding portion including a nut and a shape memory alloy spacer inserted between the nut and the outer ring. Combination type angular contact ball bearing.