JP2004011748A - Slide bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slide bearing at low cost and with favorable precision by reducing the number of component items. <P>SOLUTION: An outer ring 2 of metal is engaged in a bearing housing 8 of metal, and an inner ring 3 of resin is injection-molded on an inner circumferential surface of the outer ring 2. With the inner ring 3, a shaft 9 is engaged. The inner ring 3 is rotatable to the outer ring 2, and protruded parts 5 and recessed parts 4 are respectively provided in an inner circumferential surface of the outer ring 2 and an outer circumferential surface of the inner ring 3, thereby the inner ring 3 is not deflected or removed when the inner ring 3 is rotated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a slide bearing which includes an outer ring and a resin inner ring, and in which the inner peripheral surface of the outer ring slides against the outer peripheral surface of the inner ring.
[0002]
[Prior art]
Conventionally, a plain bearing is generally provided with a bearing alloy layer on the inner peripheral surface of a cylindrical metal backing metal, and an appropriate clearance is provided between the bearing alloy layer and the shaft. However, in a case where high precision is required, for example, in a precision instrument or the like, the shaft is not allowed to swing due to such a clearance.
[0003]
In order to eliminate such shaft runout, for example, there is a type in which a resin liner is injection-molded between an outer ring and an inner ring made of metal, and then heat-treated to make the liner rotatable with respect to the inner ring. In this case, the shaft and the inner ring are tightly fitted and integrated, and the sliding surfaces are the inner peripheral surface of the liner and the outer peripheral surface of the inner ring.
[0004]
[Problems to be solved by the invention]
However, in such a slide bearing composed of the outer ring, the liner, and the inner ring, although the shaft runout can be prevented, the number of components constituting the slide bearing is three, and the cost is high.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sliding bearing that can prevent shaft runout and reduce the number of parts.
[0005]
[Means to solve the problem]
In order to achieve the above object, the sliding bearing of the present invention comprises an outer ring, and a resin inner ring provided on the inner peripheral surface of the outer ring by injection molding and rotatable with respect to the outer ring, wherein the outer ring and the inner ring are It has a ridge portion and a concave ridge portion that are fitted to each other to prevent slippage, the outer ring is fitted to the bearing housing, and the inner ring is fitted to the shaft (the invention of claim 1).
[0006]
According to this configuration, the outer ring is fitted to the bearing housing, the inner ring is fitted to the shaft, and the sliding surfaces are the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring. In this case, the inner race is injection molded on the inner peripheral surface of the outer race. At the time of injection molding, the injection material (injection-molded inner ring) is in close contact with the inner peripheral surface of the outer ring, but contracts due to cooling. Since the gap created between the inner ring and the outer ring due to this contraction is very small, there is no backlash between the inner and outer rings, and shaft runout can be prevented.
[0007]
Further, the number of parts constituting the slide bearing can be reduced to two, that is, the outer ring and the inner ring. Here, the sliding surfaces of the inner ring and the outer ring, that is, the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring have a convex ridge and a concave ridge fitted to each other. For this reason, the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring are fitted to each other, and when the two surfaces rotate and slide, the inner ring does not shift or slip off in the axial direction with respect to the outer ring. .
Further, the sliding bearing of the present invention is characterized in that both ends in the axial direction on the inner peripheral surface of the inner ring have an inner diameter larger than the outer diameter of the shaft (the invention of claim 2).
[0008]
According to this configuration, since both ends in the axial direction of the inner race are portions larger in diameter than the outer diameter of the shaft (increased inner diameter), the central portion in the axial direction is a portion that fits tightly with the shaft (density). Fitting part). For this reason, when inserting the tip portion of the shaft into the inner ring, it is easy to insert it at first, since it is sufficient to insert it into the enlarged inner diameter portion, and thereafter the inner peripheral surface of the portion serves as a guide, and the tip of the shaft is Since the guide is guided to the central portion in the axial direction, it can be relatively easily inserted into the tightly-fitted portion. Further, since the axial length of the closely-fitted portion is shortened, the frictional resistance is relatively small, and Can be easily passed through the close fitting portion.
[0009]
As described above, in order to improve the insertability of the shaft, the inner diameter of both ends in the axial direction of the inner ring is enlarged so that a gap is formed between the inner ring and the shaft, but in the present invention, the inner ring is integrally formed with the shaft. It rotates, and the contact surface between the inner ring and the outer ring is a sliding surface. Therefore, even if the contact area between the inner ring and the shaft decreases, the surface pressure on the sliding surface increases by performing the above. There is no danger that the life will be shortened.
[0010]
Further, the sliding bearing of the present invention has a portion in the outer ring where the outer diameter of the outer ring is small in diameter and is not in contact with the bearing housing, and in the inner ring, the inner diameter of the inner ring is large in diameter and is in non-contact with the shaft. And a portion where the outer ring is not in contact with the bearing housing and a portion where the inner ring is not in contact with the shaft are provided at positions shifted from each other (the invention of claim 3). .
[0011]
Here, when the inner race and the outer race are tightly fitted to the shaft and the bearing housing, respectively, and especially when they are slightly fitted, the inner race swells outward and the outer race narrows inward. Then, the pressure acting between the sliding surfaces of the inner ring and the outer ring increases, and as a result, wear progresses early and the life is shortened. However, according to the configuration of the third aspect of the invention, the axial position of the portion where the outer ring is not in contact with the bearing housing and the position of the inner ring where the inner ring is not in contact with the shaft are shifted. That is, at the same axial position as the portion where the inner ring contacts the shaft, the outer ring is not in contact with the bearing housing, and there is a gap between them.At the same axial position as the portion where the outer ring contacts the bearing housing, the inner ring is It is not in contact with the shaft and there is a gap between them.
[0012]
When the outer ring contracts inward at a portion where the outer ring comes into contact with the bearing housing, the inner ring contracts inward in a gap between the shaft and the inner ring, thereby reducing the contact pressure with the outer ring. Further, when the inner ring expands outward at a portion where the inner ring comes into contact with the shaft, the outer ring flexes outward in a gap between the inner ring and the bearing housing to reduce the contact pressure with the inner ring. Therefore, early wear can be prevented, and the life can be extended.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. First, a first embodiment will be described with reference to FIGS. As shown in FIG. 1, the sliding bearing 1 is configured such that a cylindrical inner ring 3 is provided on an inner peripheral surface of a cylindrical outer ring 2 in a fitted state. The outer ring 2 is made of metal (iron, aluminum, alloys thereof, etc.), the inner ring 3 is made of resin (POM: polyoxymethylene, PPS: polyphenylene sulfide, etc.), and the width of the outer ring 2 and the inner ring 3 in the axial direction is: Almost the same.
[0014]
The inner peripheral surface of the outer ring 2 is provided with a concave ridge 4 extending in the circumferential direction at a central portion in the axial direction. In addition, a ridge 5 extending in the circumferential direction is provided at a central portion in the axial direction of the outer peripheral surface of the inner ring 3 corresponding to the concave ridge 4. In the inner diameter of the inner ring 3, both ends in the axial direction are larger in diameter than the central portion in the axial direction. As described above, the inner ring has, on its inner surface, a reduced inner diameter portion (closely fitted portion with the shaft) 6 which is located at the center in the axial direction and has a smaller inner diameter, and which has an inner diameter which is located at both ends in the axial direction. It has a certain inner diameter enlarged portion 7.
[0015]
Here, the resin inner ring 3 is formed by injection molding on the metal outer ring 2, and the inner ring 3 becomes rotatable with respect to the outer ring 2 by contraction after molding. Note that the clearance between the outer ring 2 and the inner ring 3 can be adjusted by the amount of contraction. The amount of shrinkage can be adjusted by adjusting the filling amount of the filler such as fiber into the resin, the mold temperature, the molding pressure, and the injection speed.
[0016]
Next, a usage mode of the above-described slide bearing 1 will be described. As shown in FIG. 2, in the sliding bearing 1, the outer peripheral surface of the outer ring 2 is fitted and fixed to the inner peripheral surface of a metal bearing housing 8. A shaft 9 is inserted into the inner ring 3 of the sliding bearing 1 fixed to the bearing housing 8. At this time, since both ends in the axial direction of the inner ring 3 are the inner diameter enlarged portions 7, the shaft 9 can be easily inserted into the inner ring 3. Further, the shaft 9 inserted into the inner-diameter enlarged portion 7 of the inner ring 3 is thereafter guided to the inner-diameter enlarged portion 7 and guided to the inner-diameter reduced portion 6 of the inner ring 3, so that it is easy to fit into the inner-diameter reduced portion 6. Further, when the shaft 9 is pushed into the inner diameter reducing portion 6, the surface in contact with the inner ring 3 and the shaft 9 (the inner diameter reducing portion 6) is shortened in the axial direction.
[0017]
When the shaft 9 is fitted to the slide bearing 1 in this manner, the inner ring 3 and the shaft 9 rotate integrally, and the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the inner ring 3 slide. At this time, as described above, the concave portion 4 is provided on the inner peripheral surface of the outer ring 2, and the convex portion 5 is provided on the outer peripheral surface of the inner ring 3. Also, even if the inner ring 3 rotates, it does not shift or come off in the axial direction. In addition, since the sliding surface between the outer ring 2 and the inner ring 3 is large over substantially the entire inner peripheral surface of the outer ring 2 and the entire outer peripheral surface of the inner ring 3, the surface pressure of each other is reduced and the sliding surface is less worn. The inner ring 3 and the shaft 9 do not necessarily need to rotate integrally, and the shaft 9 may rotate with respect to the inner ring 3 in some cases.
[0018]
Next, FIG. 3 shows a second embodiment of the present invention. A different point from the first embodiment is on the outer peripheral surface of the outer ring 2. In FIG. 3, the same parts as those in the first embodiment are denoted by the same reference numerals, detailed description thereof will be omitted, and only different parts will be described. In the sliding bearing 1 of the second embodiment, a small-diameter portion 10 whose outer diameter is smaller than the both ends in the axial direction is provided at the central portion in the axial direction on the outer peripheral surface of the outer ring 2. Therefore, when the outer ring 2 is fitted into the bearing housing 8 in a slightly press-fitted manner, the outer peripheral surface of the outer ring 2 comes into contact with the bearing housing 8 at both ends in the axial direction and shrinks in the inner diameter direction. 10 is non-contact and has a gap 11 between the bearing housing 8 and the outer peripheral surface of the outer ring 2.
[0019]
On the other hand, both ends in the axial direction of the inner peripheral surface of the inner ring 3 are configured such that the inner diameter is larger than the central portion in the axial direction, as in the first embodiment. Therefore, when the shaft 9 is fitted in a slightly press-fitted manner, the inner peripheral surface of the inner ring 3 comes into contact with the shaft 9 at the inner diameter reduction portion 6 at the axial center and expands in the outer diameter direction. The enlarged portion 7 becomes non-contact, and has a gap 12 between the shaft 9 and the inner peripheral surface of the inner ring 3.
[0020]
As described above, the small-diameter portion 10 of the outer ring 2 and the inner-diameter enlarged portion 7 of the inner ring 3 are located at positions shifted from each other in the axial direction. The small-diameter portion 10 of the outer ring 2 and the reduced-diameter portion 6 of the inner ring 3 are located at the same position in the axial direction, and their lengths are equally determined. The large-diameter portions 13 at both ends in the axial direction are located at the same position in the axial direction, and their lengths are determined equally.
[0021]
In the present embodiment, the gap 11 and the portion where the inner peripheral surface of the inner race 3 comes into contact with the shaft 9 (the inner diameter reduction portion 6) are at the same position in the axial direction. For this reason, the outer ring 2 can be bent in accordance with the amount by which the inner ring 3 expands in the outer diameter direction. In addition, the gap 12 (the large-diameter portion 13) where the outer peripheral surface of the outer ring 2 contacts the bearing housing 8 is the same position in the axial direction. For this reason, the inner ring 3 can be bent in accordance with the contraction of the outer ring 2 in the radial direction. As described above, the pressure relationship between the inner peripheral surface of the outer ring 2 that slides and the outer peripheral surface of the inner ring 3 is such that one of them releases the pressure, so that the frictional resistance between the surfaces decreases, and a long life is obtained. It becomes the sliding bearing 1.
[0022]
Finally, FIG. 4 shows a third embodiment of the present invention, which differs from the first and second embodiments in the form of a ridge on the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring. It is a form of the ridge in FIG. In FIG. 4, the same portions as those of the first and second embodiments are denoted by the same reference numerals, detailed description thereof will be omitted, and only different portions will be described. In the sliding bearing 1 according to the third embodiment, the entire inner peripheral surface of the outer ring 3 is formed as a convex ridge portion 14 whose axial cross section has a circular arc convex shape. Corresponding to the ridges 14, the entire outer peripheral surface of the inner ring 3 is formed as a ridge 15 having an arc-shaped concave cross section in the axial direction.
[0023]
【The invention's effect】
As described above, according to the sliding bearing of the present invention, the following effects can be obtained. According to the first aspect, the number of parts constituting the sliding bearing can be reduced to two, and the manufacturing cost can be reduced.
According to the second aspect, since both sides in the axial direction of the inner peripheral surface of the inner ring have an inner diameter larger than the outer diameter of the shaft, the portion serves as a guide, so that the shaft can be easily inserted.
According to the third aspect, the contact pressure on the sliding surface between the outer ring and the inner ring is reduced, and the life of the slide bearing is extended.
[Brief description of the drawings]
FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention. FIG. 2 is a vertical sectional side view showing a use mode. FIG. 3 is a diagram corresponding to FIG. 2 showing a second embodiment of the present invention. FIG. 2 corresponding to FIG. 2 showing a third embodiment of the present invention.
2 is an outer ring, 3 is an inner ring, 4 is a concave ridge, 5 is a convex ridge, 8 is a bearing housing, 9 is a shaft, 13 is a convex ridge, and 14 is a concave ridge.

Claims (3)

Outer ring,
A resin inner ring provided on the inner peripheral surface of the outer ring by injection molding and rotatable with respect to the outer ring;
The outer ring and the inner ring have a convex ridge and a concave ridge that are fitted to each other to prevent detachment, the outer ring is fitted to a bearing housing, and the inner ring is fitted to a shaft. Plain bearing. The sliding bearing according to claim 1, wherein both axial ends of the inner peripheral surface of the inner ring have an inner diameter larger than an outer diameter of the shaft. The outer ring has a portion whose outer diameter is small and is not in contact with the bearing housing, and the inner ring has a portion whose inner diameter is large and is not in contact with the shaft, and the outer ring is a bearing housing. The sliding bearing according to claim 1 or 2, wherein a portion that is not in contact with the shaft and a portion of the inner ring that is not in contact with the shaft are provided at positions shifted from each other in the axial direction.

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