JPS62124322A - Fastening structure for ceramic bearing - Google Patents

Abstract

PURPOSE:To correct automatically generation of a gap due to temperature variations by inserting, a bush having a particular linear expansion coefficient and deforming easily elastically in the circumferential direction, into a gap between a housing and a ceramic bearing. CONSTITUTION:A bush 4 is inserted into a gap between a housing 2 and a ceramic bearing 1, while said bush is composed of a material having a particular linear expansion coefficient determined by the linear expansion coefficient and the size of the housing 2 and the ceramic bearing 1 and having a function of being deformed easily elastically in the circumferential direction. As a result, generation of a gap depending on the temperature variations can be automatically corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fastening structure for a ceramic bearing, and particularly to a fastening structure for a ceramic bearing suitable for use in a location subject to temperature changes.

[One Seventeenth View of the Invention] In the conventional ceramic bearing fastening structure-1, the gap adjustment between the bearing and the housing was, for example, disclosed in Japanese Utility Model Publication No. 55-2889.
As described in No. 8, a bushing is inserted and its elastic deformation is utilized, or as described in Japanese Utility Model Application Laid-open No. 50-148440, a filling film is formed. However, these technologies are difficult to prevent gap formation and to improve heat resistance for ceramic bearings using structural ceramics such as silicon nitride, sialon, or silicon carbide, which have a coefficient of linear expansion that is significantly different from that of steel materials. was insufficient.

Further, in FIG. 14, a bushing 3 is inserted between the bearing 1 and the housing 2, and its elastic deformation is utilized.

In this structure, as the housing thermally expands, the bushing can maintain close contact with the inner periphery of the housing due to thermal expansion and elastic deformation, as shown in Figure 15, but since the thermal expansion of the ceramic bearing is small, the outer periphery of the bearing It had the disadvantage of creating a gap between the and bush. In such a structure, in addition to deterioration of bearing performance such as vibration generation, there is a high possibility that impact force will be generated when a load is applied.

On the other hand, since ceramics are brittle, their strength and reliability are significantly impaired when subjected to loads such as impact.

For this reason, it is possible to take advantage of the heat resistance, which is one of the characteristics of ceramic bearings, by preventing gaps from forming in the high temperature range of hundreds of dust particles.
．． A good fastening structure is essential.

[Purpose of the invention]

The purpose of the present invention is to maintain stable bearings without creating gaps due to differences in thermal expansion of the materials between the bearing and the housing in which the bearing is mounted, when using the ceramic bearing in a location subject to temperature changes. The purpose of the present invention is to provide a fastening structure for ceramic bearings that enables the following.

[Summary of the invention]

In order to achieve the object 1-, the present invention is made of a material having a specific coefficient of linear expansion determined by the coefficient of linear expansion and dimensions of the housing and the ceramic bearing, and has the ability to easily deform elastically in the circumferential direction. By inserting a bushing with a
This is what IIT Noh is all about.

[Embodiments of the invention]

The present invention will be explained in detail with reference to FIG. 1. Thermal expansion deformation when a fastening part consisting of a housing 2 and a bushing 4 having 6 outer diameters 1-9 and 1 inner diameter is exposed to a temperature of 'r°C. think of. Now, the linear expansion coefficient of each bearing α is
Let the housing α□ and the bushing α, and the thermal expansion change in each case be the bearing outer diameter A d * and the housing inner diameter AD□.
, the inner diameter Ad and the outer diameter AD of the bushing. At this time, the 7th order formula is established.

zz d R=α8・T−d l/l D
M = a, I・−r−D′−・(
1) 4d α・T−d, /1D=α・′I−・0 When it is assumed that it can be freely deformed in the circumferential direction, in order not to create a gap in the radial direction.

AD, -Ac3. l=/JD-Ad ,, α=(α□・D-α,・d)/(D-d ・・(
2) Furthermore, the thermal expansion deformation in the circumferential direction is expressed by a linear equation, where S j and g S o are the deformation differences between the bush, the bearing, and the housing, respectively.

By the way, when α in equation (2) is substituted into equation (3), we get 7 Generally, the coefficient of linear expansion of structural ceramics is smaller than that of steel materials.For example, when the housing is made of carbon steel and the bearing is made of silicon nitride, For αee h t t X I
O-'/"C, α-3X 10-'/℃. Therefore, α□-α, 〉0 Therefore, from equation (4) and (3), 〉0...(5
) S i >O, S o >O−(6). From this, it can be seen that the thermal expansion deformation of the bushing in the circumferential direction is larger than that of the bearing and housing. −
As an example, d = 30 nwn, D = 42
nn.

Consider the case where T = 500°C. (2), (3) formula%
Formula % On the other hand, as a material having the above linear expansion coefficient α, 30
4 stainless steel m (α+V shape 18X10-++/'C)
.

2ONim (same 2oxto-'/'C), brass (same 1
8 to 23 x 10-''/°C).

In other words, by using a bushing that has α obtained from equation (2) and has a material and structure that can elastically absorb circumferential deformation greater than the value obtained from equation (3), it is possible to
Ceramic bearings can be fastened without creating gaps despite temperature fluctuations.

On the other hand, if the material of the bushing is determined based on heat resistance etc., if D and d satisfy equation (2), the same result will be 1! ) can be done.

Furthermore, by selecting a material with a coefficient of linear expansion larger than α obtained from equation (2), the tightening force of the bushing and spring bearing increases as it reaches 1λ, so that reliable tightening can be achieved.

Next, a fastening structure in the case where there is no suitable heat material having α given by equation (2) will be described with reference to FIG. 2. In addition to the bushing 1, by providing a buffer layer 5 that has the function of elastically correcting deformation in the radial direction, if the coefficient of linear expansion of the bushing material is larger than or smaller than the value of equation (2), It is also possible to stably fasten bearings that are subject to temperature fluctuations.

Next, specific examples of the present invention will be described.

Figure 3 (, 1) (b) is an example of a bushing with a function of absorbing deformation in the circumferential direction, which is used in the fastening end structure of the present invention.One bushing 6 is given by equation (3). A slit 7 having a width S larger than the circumferential deformation area is provided at one location on the circumference -L.

The slit width of this pushbutton 6 decreases only in the circumferential deformation region when the temperature is high, and when the noise is low (room temperature), the elastic recovery force of the pushbutton 6 restores the original shape. This kind of deformation due to y1 temperature or temperature drop can be made into a bullet-1 (1 deformation), so there is no fear of exhaustion and it is a highly reliable deformation absorption function.

By the way, there is no need to specify the shape of the sling I- in the axial direction, and the shape of the sling 1-9 such as the bush 8 shown in FIG. 4 may be used. Also, Surin 1-width S is (
It is also possible to make it smaller than the candy in formula 3). In this case, as shown in Figures 5 (a) and (b), the bush IO will escape in the axial direction as shown by the break 1i11, and (3)
To absorb the circumferential deformation of Eq. Furthermore, as shown in FIG. 6, by making the bushing 12 coil-shaped,
As another example in which a similar effect can be obtained, FIG. 7 shows an embodiment in which slits are provided at two or more locations on the circumference. The bush 13 is an example in which slits 1.4 and 1.5 are provided at two locations.

The slit width S at this time may be 1/2 of that in the case described in -1. It is.

Another embodiment will be explained with reference to FIGS. 8(a) and 8(b). Portions 19, 20, 21 where the wall thickness is reduced in the axial direction at four locations on the circumference 42 of the bush 18. ．． 22, and this part 1
This is an example in which elastic deformation of numbers 9 to 20 is facilitated. When the temperature is high, deformation as shown by the broken line 23 occurs, thereby absorbing thermal expansion deformation of the bush 8 in the circumferential direction. Figure 9(a),
(+)) is another embodiment based on the same idea), in which portions 25° 26, 27, 28 of the circumference of the bushing 24 are provided with thinner wall thickness in the direction of the radius lj at positions −1 to 4. . Broken line 29
By the modification shown in (1), the same effect as described in -1- can be obtained.

As another example of application, when the axial length Q of the bushing 30 becomes long, as shown in FIG. 10 in the case of a ceramic sliding bearing with a long shaft length, the axial expansion of the bushing 30 in the axial direction is taken into account. It is necessary to shorten the axial length I of the ceramic bearing 3j-.

Next, an embodiment of the F & surgical layer that achieves the radial deformation absorbing function shown in FIG. 2 will be described with reference to FIG. 11.

The figure is a stress-strain diagram of a shape memory alloy (INi-'I-i alloy).6 This alloy is known to have superelastic properties Vl. That is, when an alloy that has been stretched to point A at a low temperature (room temperature) is heated, it returns to the 0 point via the n, 0 point. The B barrier layer 5 shown in FIG. When it is attached to the outer periphery of the bushing 4 as shown in 1 and heated, it comes into close contact with the bushing at 911 degrees of restoration, resulting in the state of point B. If an alloy is assembled into the housing 5 in this state and an alloy that produces a restoring effect at the operating temperature (high temperature) of the device is selected, the device will operate at point 0. At this time, the buffer layer expands in the radial direction in response to the contraction in the circumferential direction. In other words, the effect of correcting the insufficient thermal expansion of the bushing 40 in the semicircular direction can be increased by 1ul. Therefore, the coefficient of linear expansion of the material of the bushing 4 is (2)
When it is smaller than the formula, by providing a loose Nfj layer 5 using this alloy, it is possible to fasten the bearing without creating a gap even at high temperatures.

On the other hand, if the linear expansion coefficient of the bushing material is lower than the value of equation (2), a radial slit is provided in a part of the bushing to facilitate elastic deformation and provide a correction function. I can do it. Figure 12.

An example is shown in FIG. 13. FIG. 12 shows an example in which a slit 33 is provided in the circumferential direction on the outer periphery of the bush 32.
Figure 3 shows a slit 35t in the axial direction on the outer periphery of the bushing: 34.
! : This is an example provided.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent the gap that occurs between the housing and the ceramic bearing due to thermal deformation when the housing and the ceramic bearing are subjected to temperature changes, and the bearing can be stably held. Disturbances such as vibration and secondary N'M
This has the effect of making it possible to use the bearing by taking advantage of its heat resistance without causing damage due to force.

[Brief explanation of drawings]

1 to 13 are explanatory diagrams of a fastening structure for a ceramic bearing according to the present invention, FIG. 1 is a sectional view of the fastening structure for a ceramic bearing, FIG. 2 is a sectional view of another embodiment of the fastening structure,
Fig. 3 shows an embodiment of the bushing used in the present invention, (a) is a side view, (b) is a front view, Fig. 4 is a side view of another embodiment of the bushing, and Fig. 5 is a still another embodiment of the bushing. In the example (,
) is a side view, (1)) is a front view, FIG. 6 is a side view of yet another embodiment of the bushing, FIG. 7 is a front view of still another embodiment of the bushing, and FIG. 8 is a further view of the bushing. In other embodiments, (1) is a side view, (b) is a front view, and FIG. 9 is another embodiment of the bushing, (a) is a side view, (b) is a front view, and 10th is a fastening. Cross-sectional view of another embodiment of the structure, No. 11
The figure is a diagram of the relationship between strain and stress in one embodiment of the fastening structure, and FIG. 12 is a sectional view of yet another embodiment of the bushing.
FIG. 13 is a front view of yet another embodiment of the bushing, the first
4 and 15 are explanatory diagrams of conventional ceramic bearing fastening structures. 30°32.
34... Bush, 5... Buffer layer, 31... Ceramic sliding bearing. Part 1 Early 2nd Part 3z (α) (e)) Part d Part 7 Part 90 Part 2 Part 70 Part 1 / Part 1 Part 74 Figure 1S Closed Proceedings Amendment (Method) 1. Display of the case 1988 Patent Application No. 140334 by Zuko Akira 1 Ceramic Bearing Fastening Structure 3, Capture 11:
+1 Medium) II Knee:)l
II →n,' It (乍
19 "4. Agent 6. Captivity)) > 4 Elephant Contents of brief description of drawings in the specification column 7/Oil 11"

Claims (1)

[Claims] 1. In a structure in which a ceramic bearing is fastened to a housing made of a material different from that of the bearing, the circular A fastening structure for a ceramic bearing, characterized by being provided with a bushing having a function of absorbing deformation in the circumferential direction. 2. A fastening structure for a ceramic bearing according to claim 1, characterized in that a buffer layer is provided for correcting mismatching of linear expansion coefficients of the bushings.