JP6823902B2 - Plain bearing - Google Patents

Description

The present invention relates to a slide bearing that supports a load applied to the shaft member while allowing the shaft member to move in the axial direction, and more particularly to a slide bearing suitable for a rack bush used in a steering mechanism of a vehicle.

Patent Document 1 states that, as a slide bearing suitable for a rack bush used in a vehicle steering mechanism, it is housed in a cylindrical housing in a state where axial movement is restricted, and axial movement of the rack shaft is permitted. However, plain bearings that support the load applied to the rack shaft are described.

This plain bearing includes a cylindrical bearing body into which a rack shaft is inserted, and an elastic ring that is mounted on the bearing body and is made of an elastic body such as rubber or elastomer and urges the bearing body inward in the radial direction. I have. The bearing body is made of synthetic resin and has a first slit formed along the axial direction from one end face to the other end face and an axial direction from the other end face to one end face. It has a second slit formed therein and a mounting groove formed on the outer peripheral surface of the bearing body to which an elastic ring is mounted.

According to this sliding bearing, the diameter of the bearing body is reduced by the elastic ring and the rack shaft inserted into the bearing body is tightened, so that the clearance between the inner peripheral surface of the bearing body and the outer peripheral surface of the rack shaft is set to zero. It is possible to prevent the generation of unpleasant noise due to the collision between the inner peripheral surface of the bearing body and the outer peripheral surface of the rack shaft, and to prevent the fluctuation of the friction torque due to the outer diameter dimensional error of the rack shaft.

Japanese Unexamined Patent Publication No. 2008-151289

By the way, the slide bearing described in Patent Document 1 is sandwiched between a rack shaft inserted in the bearing body and a housing in which the slide bearing is housed, and the elastic ring mounted on the bearing body is compressed and deformed. used. Therefore, there is a problem that the elastic bodies such as rubber and elastomer used for the elastic ring are deteriorated and the life of the slide bearing is shortened.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a slide bearing capable of improving the durability of an elastic body and extending the life of the elastic body.

In order to solve the above problems, in the slide bearing of the present invention, an elastic member protruding outward from the outer peripheral surface of the bearing body is attached to a cylindrical bearing body into which a shaft member is inserted and which can be expanded and contracted in the radial direction. doing. Then, the elastic member is provided with a protruding portion that projects outward while inclining in the radial direction of the bearing body and comes into contact with the inner peripheral surface of the housing, for example, when it is housed in a tubular housing. ..

For example, the first aspect of the slide bearing of the present invention is
A plain bearing housed in a tubular housing that supports a load applied to the shaft member while allowing at least one of axial movement and rotation of the shaft member.
A tubular bearing body that can expand and contract in the radial direction,
An elastic member mounted on the bearing body and having a protruding portion protruding outward from the outer peripheral surface of the bearing body while being inclined with respect to the radial direction of the bearing body .
The bearing body
At one end, it has an engaging portion that projects outward from the outer peripheral surface and is inserted into an annular groove formed in the circumferential direction on the inner peripheral surface of the housing.
The elastic member is
It further has an engaging elastic portion that is inserted into the annular groove of the housing together with the engaging portion of the bearing body and abuts on the side surface of the annular groove.
When the slide bearing is housed in the housing, the protruding portion abuts on the inner peripheral surface of the housing to urge the bearing body inward in the radial direction .

The second aspect of the slide bearing of the present invention is
A tubular bearing body that can expand and contract in the radial direction,
An elastic member mounted on the bearing body and having a protruding portion protruding outward from the outer peripheral surface of the bearing body while being inclined with respect to the radial direction of the bearing body.
The bearing body
It is formed on the outer peripheral surface and has a holding groove whose bottom groove width is wider than the groove width of the opening.
The elastic member is
It is housed in the holding groove of the bearing body and further has a held portion having the same shape as the holding groove .

In the present invention, when the slide bearing is housed in, for example, a tubular housing, the radial outer end of the elastic member abuts on the inner peripheral surface of the housing to urge the bearing body in the radial direction. To do. As a result, the diameter of the bearing body is reduced, and the shaft member inserted into the bearing body is tightened. At this time, the protruding portion of the elastic member comes into contact with the inner peripheral surface of the housing and is bent and deformed. Deterioration of elastic bodies such as rubber and elastomers used for elastic members is generally more affected by compressive deformation than bending deformation. According to the present invention, a part of the compressive stress applied to the elastic member can be released by bending deformation, so that the amount of compressive deformation can be reduced by that amount, thereby improving the durability of the elastic member and making the slide bearing. The life can be extended.

FIG. 1 is a partial cross-sectional view of a part of a steering mechanism of a vehicle in which the rack bush 1 according to the first embodiment of the present invention is used. 2 (A), 2 (B) and 2 (C) are a front view, a side view and a rear view of the rack bush 1. 3 (A), 3 (B) and 3 (C) are front views, side views and rear views of the bush body 2, and FIGS. 3 (D) and 3 (E) are shown in FIG. 3 (E). AA cross-sectional view and BB cross-sectional view of the bush body 2 shown in A), FIG. 3 (F) is an enlarged view of a portion C of the bush body 2 shown in FIG. 3 (A). 4 (A), 4 (B) and 4 (C) are a front view, a top view and a side view of the elastic member 3, and FIG. 4 (D) is an enlargement of the D portion of FIG. 2 (A). It is a figure. 5 (A), 5 (B) and 5 (C) are a front view, a side view and a rear view of the rack bush 1'according to the second embodiment of the present invention. 6 (A), 6 (B) and 6 (C) are front views, top views and side views of the elastic member 3a, and FIG. 6 (D) is a portion E shown in FIG. 5 (B). It is an enlarged view of the arrow in the F direction shown in FIG. 5 (C). 7 (A), 7 (B) and 7 (C) are a front view, a top view and a side view of the elastic member 3b, and FIG. 7 (D) is an enlargement of the G portion of FIG. 7 (C). It is a figure. FIG. 8 is a top view of the elastic member 3c.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a partial cross-sectional view of a part of the steering mechanism of the vehicle in which the rack bush 1 according to the present embodiment is used.

As shown in the figure, the rack bush 1 according to the present embodiment is housed in the cylindrical housing 4 in a state where the movement in the axis O direction is restricted, and the rack shaft 5 is allowed to move in the axis O direction. , Supports the load applied to the rack shaft 5.

2 (A), 2 (B) and 2 (C) are a front view, a side view and a rear view of the rack bush 1.

As shown in the figure, the rack bush 1 includes a cylindrical bush body 2 into which the rack shaft 5 is inserted, and a plurality of elastic members 3 mounted on the bush body 2.

3 (A), 3 (B) and 3 (C) are front views, side views and rear views of the bush body 2, and FIGS. 3 (D) and 3 (E) are shown in FIG. 3 (E). AA cross-sectional view and BB cross-sectional view of the bush body 2 shown in A), FIG. 3 (F) is an enlarged view of a portion C of the bush body 2 shown in FIG. 3 (A).

The bush body 2 is made of a synthetic resin having good sliding characteristics such as polyacetal resin, polyamide resin, polyethylene resin, etc., and is formed on the inner peripheral surface 20 and is inserted into the outer peripheral surface 50 of the rack shaft 5 as shown in the figure. Holds a sliding surface 21 that is in sliding contact, a plurality of first slits 25 and second slits 26 that are alternately arranged at equal intervals in the circumferential direction, an engaging portion 27 formed on the outer peripheral surface 22, and an elastic member 3. It is provided with a plurality of holding grooves 28 and the like.

The first slit 25 is formed along the axis O direction from one end face 23 toward the other end face 24, and the second slit 26 is formed along the axis O direction from the other end face 24 toward one end face 23. Is formed. The bush main body 2 is easily deformed in the diameter reduction direction by a plurality of first slits 25 and second slits 26 which are alternately arranged at equal intervals in the circumferential direction.

The engaging portion 27 projects outward from the outer peripheral surface 22 on one end surface 23 side, and is inserted into an annular groove 41 formed in the circumferential direction on the inner peripheral surface 40 of the housing 4. As a result, the movement of the rack bush 1 housed in the housing 4 in the axial O direction is restricted.

The holding groove 28 is formed on the outer peripheral surface 22 along the axis O direction so as to penetrate both end surfaces 23 and 24. Further, the holding groove 28 is formed so that the groove width W1 of the bottom portion 280 is wider than the groove width W2 of the opening 281.

4 (A), 4 (B) and 4 (C) are a front view, a top view and a side view of the elastic member 3, and FIG. 4 (D) is an enlargement of the D portion of FIG. 2 (A). It is a figure.

The elastic member 3 is formed of an elastic body such as rubber or elastomer, and includes a held portion 31 and a pair of protruding portions 30a and 30b formed on the upper surface 310 of the held portion 31 as shown in the figure. There is.

The protrusions 30a and 30b project outward from the outer peripheral surface 22 of the bush body 2 in the rack bush 1, and the diameter D1 of the circle C connecting the vertices of the protrusions 30a and 30b (see FIG. 2A) is the housing. The amount of protrusion from the upper surface 310 of the held portion 31 is set so as to be squeezed with respect to the inner diameter D2 (see FIG. 1) of 4. As a result, when the rack bush 1 is housed in the housing 4, the elastic members 3 have the protrusions 30a and 30b in contact with the inner peripheral surface 40 of the housing 4 and urge the bush body 2 inward in the radial direction. To do.

Further, as shown in FIG. 4D, the protruding portions 30a and 30b of the elastic member 3 are circumferential with respect to a straight line extending in the radial direction R through the center of the bush body 2 in a cross section perpendicular to the axis O direction. It is inclined in the direction S. Therefore, when the rack bush 1 is housed in the housing 4, the protruding portions 30a and 30b come into contact with the inner peripheral surface 40 of the housing 4 and are bent and deformed in the circumferential direction S. Further, the opening 281 of the holding groove 28 of the bush body 2 is formed so as to have a groove width W2 capable of forming accommodating regions 282a and 282b on both sides of the protruding portions 30a and 30b of the elastic member 3 in the circumferential direction S. Has been done. The protruding portions 30a and 30b that are bent and deformed in contact with the inner peripheral surface 40 of the housing 4 are housed in the housing areas 282a and 282b.

The held portion 31 has the same shape as the bottom portion 280 of the holding groove 28 of the bush body 2, and the elastic member 3 is slid in the axial O direction to move the held portion 31 to the bottom portion 280 of the holding groove 28 of the bush body 2. By inserting, the elastic member 3 is held in the holding groove 28 of the bush body 2. Since the holding groove 28 of the bush body 2 is formed so that the groove width W1 of the bottom portion 280 is wider than the groove width W2 of the opening 281, the elastic member 3 held by the holding groove 28 falls off in the radial direction. Can be prevented.

The first embodiment of the present invention has been described above.

In the present embodiment, when the rack bush 1 is housed in the cylindrical housing 4, the protruding portions 30a and 30b of the elastic member 3 come into contact with the inner peripheral surface 40 of the housing 4 to bring the bush body 2 in the radial direction. Encourage inward. As a result, the bush body 2 is reduced in diameter, and the rack shaft 5 inserted into the bush body 2 is tightened. Here, since the protruding portions 30a and 30b of the elastic member 3 are inclined in the circumferential direction S with respect to the radial direction R in the cross section perpendicular to the axis O direction, at this time, the protrusions 30a and 30b of the elastic member 3 and the inner peripheral surface 40 of the housing 4 It abuts and is bent and deformed in the circumferential direction S, and is accommodated in the accommodating areas 282a and 282b of the holding grooves 28 of the bush body 2 formed on both sides of the projecting portions 30a and 30b in the circumferential direction S. Deterioration of elastic bodies such as rubber and elastomer used for the elastic member 3 is generally more affected by compressive deformation than bending deformation. According to the present embodiment, a part of the compressive stress applied to the elastic member 3 when the rack bush 1 is housed in the housing 4 can be released by bending deformation of the protrusions 30a and 30b, so that the amount of compression is reduced by that amount. The amount of deformation can be reduced, thereby improving the durability of the elastic member 3 and extending the life of the rack bush 1.

Further, in the present embodiment, the groove width W1 of the bottom 280 of the holding groove 28 of the bush main body 2 is made wider than the groove width W2 of the opening 281 and the held portion 31 of the elastic member 3 is held by the bush main body 2. The elastic member 3 is held in the holding groove 28 of the bush body 2 by having the same shape as the bottom 280 of the groove 28 and inserting it into the bottom 280 of the holding groove 28. Therefore, it is possible to prevent the elastic member 3 held in the holding groove 28 of the bush body 2 from falling off in the radial direction.

Further, when the slide bearing described in Patent Document 1 is inserted into the housing 4, it is supported by the housing 4 at a point in the axial O direction (one elastic ring supports one point, and two elastic rings support two). (Point support), therefore, the outer peripheral surface of the bearing body may be tilted in the axial O direction in the housing 4. In this respect, in the present embodiment, since the elastic member 3 extends in the axis O direction, when it is inserted into the housing 4, it is supported by the housing 4 by a line in the axis O direction, and therefore, the bush main body. It is possible to reduce the possibility that the outer peripheral surface 22 of 2 is tilted in the axis O direction in the housing 4.

Further, in the present embodiment, since the elastic member 3 has a shape utilizing bending deformation, there is an advantage that the degree of freedom of the shape is high and the rigidity can be easily controlled.

[Second Embodiment]
The rack bush 1'according to the present embodiment is also housed in the cylindrical housing 4 in a state where the movement in the axial O direction is restricted, like the rack bush 1 according to the first embodiment shown in FIG. It supports the load applied to the rack shaft 5 while allowing the rack shaft 5 to move in the axis O direction.

5 (A), 5 (B) and 5 (C) are a front view, a side view and a rear view of the rack bush 1'according to the second embodiment of the present invention.

The difference between the rack bush 1 ′ according to the present embodiment and the rack bush 1 according to the first embodiment is that the elastic member 3a is used instead of the elastic member 3. Other configurations are the same as those of the rack bush 1 according to the first embodiment.

6 (A), 6 (B) and 6 (C) are front views, top views and side views of the elastic member 3a, and FIG. 6 (D) is a portion E shown in FIG. 5 (B). It is an enlarged view of the arrow in the F direction shown in FIG. 5 (C).

The elastic member 3a differs from the elastic member 3 of the rack bush 1 according to the first embodiment in that it has a pair of engaging elastic portions 32a and 32b. Other configurations are the same as those of the elastic member 3 of the rack bush 1 according to the first embodiment.

The engaging elastic portions 32a and 32b are formed on the engaging portion 27 side of the bush body 2 with the protrusions 30a and 30b sandwiched between the upper surface 310 of the held portion 31 and outward from the outer peripheral surface 22 of the bush body 2. Protrude. Then, it is inserted into the annular groove 41 of the housing 4 together with the engaging portion 27 of the bush body 2.

The length L1 of the engaging elastic portions 32a and 32b in the axis O direction is longer than the length L2 of the engaging portion 27 of the bush body 2 in the axis O direction, and the length of the annular groove 41 of the housing 4 in the axis O direction. It is set to be squeaky with respect to L3 (see FIG. 1). However, if the engaging elastic portions 32a and 32b have a shape in which at least one end surface protrudes from the end surface of the engaging portion 27 of the bush body 2 so as to form an annular groove 41 and a mesh in the axial O direction, the engaging elastic portions 32a and 32b are engaged. The length L1 of the elastic portions 32a and 32b in the axial O direction may be shorter than the length L2 of the engaging portion 27 of the bush body 2 in the axial O direction.

The second embodiment of the present invention has been described above.

In the present embodiment, the engaging elastic portions 32a and 32b have a shape in which at least one end surface protrudes from the end surface of the engaging portion 27 of the bush body 2 in the axial O direction, and the engaging elastic portions 32a and 32b The length L1 in the axis O direction is set so as to be squeezed with respect to the length L3 in the axis O direction of the annular groove 41 of the housing 4. Therefore, when the rack bush 1 is housed in the housing 4, it is possible to prevent the engaging portion 27 of the bush body 2 from repeatedly contacting and not contacting the side surface of the annular groove 41 of the housing 4 to generate an abnormal noise. .. Other effects are the same as those of the first embodiment of the present invention, except for the effect that the outer peripheral surface of the bush body 2 of the rack bush 1'inserted into the housing 4 can be reduced in the housing 4 in the axial O direction. The same is true.

It should be noted that the present invention is not limited to each of the above embodiments, and many modifications can be made within the scope of the gist thereof.

For example, in each of the above embodiments, the protruding portions 30a and 30b of the elastic members 3 and 3a are inclined in the circumferential direction S with respect to the radial direction R in the cross section perpendicular to the axis O direction (FIG. 4 (FIG. 4). See D)). However, the present invention is not limited to this. The protruding portions 30a and 30b of the elastic members 3 and 3a may be those that protrude outward from the outer peripheral surface 22 of the bush body 2 while being inclined with respect to the radial direction R. For example, like the elastic member 3b shown in FIG. 7, in the cross section in the axis O direction, the protruding portion 30c inclined in the axis O direction with respect to the radial direction R is formed on the upper surface 310 of the held portion 31 along the axis O direction. May be provided in plurality. In this case, it is preferable to provide the protrusions 30c at predetermined intervals so as to have a storage area 282c in which the protrusions 30c that are bent and deformed in contact with the inner peripheral surface 40 of the housing 4 are accommodated.

Further, in each of the above embodiments, the groove width at both ends of the bottom 280 of the holding groove 28 of the bush body 2 is wider than the groove width of the central portion sandwiched between the both ends, and one of them is used. The groove width of the end portions on the end faces 23 and 24 side is inclined so as to become narrower as it approaches the end faces 23 and 24, and at the same time, both ends of the held portion 31 are formed as in the elastic member 3c shown in FIG. The width of the 311a and 311b may be wider than the width of the central portion 312 sandwiched between the both end portions 311a and 311b, and the width of one end portion 311a may be inclined so as to become narrower as it approaches the end surface 313. Then, the elastic member 3 may be held in the holding groove 28 of the bush main body 2 by inserting the held portion 31 into the bottom portion 280 of the holding groove 28 of the bush main body 2 with the end portion 311a at the head. By doing so, it is possible to prevent the elastic member 3c from sliding in the shaft O direction and falling out of the holding groove 28 of the bush body 2 in the shaft O direction.

Further, in each of the above embodiments, the holding groove 28 of the bush body 2 is formed on the outer peripheral surface 22 of the bush body 2 along the axis O direction, and the elastic members 3, 3a to 3c are formed linearly. , It is held in this holding groove 28. However, the present invention is not limited to this. For example, a holding groove is formed in an annular shape on the outer peripheral surface 22 of the bush body 2 along the circumferential direction, and the holding groove is formed in a cross section in the axis O direction or a cross section perpendicular to the axis O direction in the radial direction of the bush body 2. An annular elastic member having a protruding portion that protrudes outward from the outer peripheral surface 22 while inclining with respect to the inner peripheral surface 40 of the housing 4 may be attached.

Further, in each of the above embodiments, a plurality of first slits 25 are formed in the bush body 2 from one end face 23 toward the other end face 24 along the axis O direction, and one from the other end face 24. A plurality of second slits 26 are formed along the axis O direction toward the end surface 23 of the above. However, the present invention is not limited to this. The bush body 2 may have a tubular shape that can be expanded and contracted in the radial direction. For example, a slit formed along the axis O direction from one end face to the other end face may be provided so that the slit can be expanded and contracted in the radial direction, or a thin portion is provided instead of the slit. As a result, it may be expandable and contractible in the radial direction.

Further, in each of the above embodiments, the shape of the bush body 2 is cylindrical, but it may be a cylindrical shape that matches the shape of the rack shaft 5 to be inserted. Further, in the present embodiment, the bush body 2 and the elastic members 3, 3a to 3c are made of different materials, but both may be made of the same material.

Further, the present invention is not limited to rack bushes. The present invention is widely applicable to plain bearings that support a load applied to the shaft member while allowing at least one of axial movement and rotation of the shaft member. For example, the present invention can be applied to a steering column bush that supports a load applied to the steering column while allowing the steering column to rotate.

1, 1': Rack bush, 2: Bush body, 3, 3a to 3c: Elastic member, 4: Housing, 5: Rack shaft, 20: Inner peripheral surface of bush body 2, 21: Sliding surface of bush body 2 , 22: Bush body 2 outer peripheral surface, 23, 24: Bush body 2 end surface, 25: First slit, 26: Second slit, 27: Engagement part, 28: Holding groove, 30a to 30c: Projection part, 31: Held part, 32a, 32b: Elastic part for engagement, 40: Inner peripheral surface of housing 4, 41: Circular groove, 50: Outer surface of rack shaft 5, 280: Bottom of holding groove 28, 281: Holding groove 28 openings, 282a to 282c: accommodation area, 310: upper surface of held portion 31, 313: end face of elastic member 3c

Claims (7)

A plain bearing housed in a tubular housing that supports a load applied to the shaft member while allowing at least one of axial movement and rotation of the shaft member.
A tubular bearing body that can expand and contract in the radial direction,
An elastic member mounted on the bearing body and having a protruding portion protruding outward from the outer peripheral surface of the bearing body while being inclined with respect to the radial direction of the bearing body.
The bearing body
At one end, it has an engaging portion that projects outward from the outer peripheral surface and is inserted into an annular groove formed in the circumferential direction on the inner peripheral surface of the housing.
The elastic member is
It further has an engaging elastic portion that is inserted into the annular groove of the housing together with the engaging portion of the bearing body and abuts on the side surface of the annular groove .
A slide bearing characterized in that when the slide bearing is housed in the housing, the protruding portion abuts on the inner peripheral surface of the housing to urge the bearing body inward in the radial direction . The slide bearing according to claim 1, wherein the bearing body is
A plain bearing characterized by further having slits formed along the axial direction from one end face to the other end face. The slide bearing according to claim 1 or 2 .
The bearing body
Further having a holding groove formed on the outer peripheral surface and having a groove width at the bottom wider than the groove width of the opening.
The elastic member is
A slide bearing that is housed in the holding groove of the bearing body and further has a held portion having the same shape as the holding groove. A tubular bearing body that can expand and contract in the radial direction,
An elastic member mounted on the bearing body and having a protruding portion protruding outward from the outer peripheral surface of the bearing body while being inclined with respect to the radial direction of the bearing body.
The bearing body
It is formed on the outer peripheral surface and has a holding groove whose bottom groove width is wider than the groove width of the opening.
The elastic member is
A slide bearing that is housed in the holding groove of the bearing body and further has a held portion having the same shape as the holding groove. The slide bearing according to claim 4 , wherein the bearing body is
A plain bearing characterized by further having slits formed along the axial direction from one end face to the other end face. The slide bearing according to any one of claims 3 to 5 .
The holding groove of the bearing body and the held portion of the elastic member are
A groove formed along the axial direction from one end face of the bearing body to the other end face, the groove width of both ends is wider than the groove width of the intermediate portion sandwiched between the both ends, and the groove on one end face side. A plain bearing characterized in that its width narrows as it approaches one of the end faces. The slide bearing according to any one of claims 3 to 6 .
The holding groove of the bearing body
A slide bearing having a storage area for accommodating the bent and deformed protruding portion of the elastic member.

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