JPH11230160A - Bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure an oil film even if a rotary shaft receives an outer force and always obtain a favorable fluid lubrication state. SOLUTION: The inner periphery surface 9 of the bearing hole 8 of an oil contained bearing 4 has a cylinder part 10 whose inner diameter is constant in an axis direction and variable opening parts M provided on both ends of the cylinder part 10 and whose inner diameter becomes bigger as it is more separated from the cylinder part 10 in the axis direction. The variable opening part M is composed of three parts such as first-third taper parts M1-M3 symmetrically. Respective taper angles of the first-third taper parts M1-M3 becomes bigger gradually as it approaches from the first taper part, M1 adjoined to the cylinder part 10 to more outer direction. The boundary part between the cylinder part 10 and the first taper part M1, the boundary part between the first taper part, M1 and the second taper part N2 and the boundary part between the second taper part M2 and the third taper part M3 are finished so as to be a curved surface. A band shape blinder part 11 is formed across the cylinder part 10 and the first-third taper parts M1-M3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bearing, and more particularly, to an oil-impregnated bearing for a small motor vehicle.

[0002]

2. Description of the Related Art Conventionally, a bearing using a porous material has been proposed. The bearing made of this porous material is impregnated with lubricating oil and used as a so-called oil-impregnated bearing. Since this oil-impregnated bearing has a self-lubricating action, it is excellent in reducing the number of times of lubricating oil replenishment and the like. As shown in the schematic diagrams of FIGS. 8 and 9, the bearing holes 52 of the oil-impregnated bearing 51 crush the holes of the surface portion 54 corresponding to the portion in contact with the rotating shaft 53, that is, the dense state, that is, the crushed portion 55 Forming the bearing 51
A structure in which an oil film 56 is secured between the contact surface of the rotary shaft 53 and the contact surface of the rotary shaft 53 has been proposed. Then, as shown in FIG. 10, as shown in FIG. 10, a favorable fluid lubrication state is realized in which the hydraulic pressure distribution becomes maximum in the rotation upstream portion of the minimum gap in the gap formed between the bearing 51 and the rotating shaft 53. In a favorable fluid lubrication state, the front body was such that the axis L0 of the bearing 51 and the axis L1 of the rotating shaft 53 were parallel to each other.

[0003]

Incidentally, there is a case where an external force is applied to the rotating shaft 53 of the motor. When an external force is applied, the rotating shaft 53 is tilted and misaligned as shown by a two-dot chain line in FIG. Therefore, in this oil-impregnated bearing 51, the bearing 5
Both sides of the cylindrical portion 57 in the one bearing hole 52 are tapered and widened at an angle θa to form a tapered portion 58 so as to absorb axial misalignment.

However, when the rotating shaft 53 inserted into the bearing hole 52 is tilted by an external force, the rotating shaft 53
Are in contact with the boundary portions (corner portions) between the cylindrical portion 57 and the tapered portion 58, respectively. This is because the angle θ0 between the central axis L0 of the bearing hole 52 (the cylindrical portion 57) and the central axis L1 of the rotating shaft 53 when it comes into contact with the corner is equal to the angle θ0 of the tapered portion 5.
This is because it is set smaller than the angle θa of FIG.

When the rotating shaft 53 comes into contact with the corner,
The oil film 56 formed at the corner is cut. Therefore,
The rotating shaft 53 partially comes into metallic contact with the bearing hole 52 without passing through the oil film 56. As a result, there arises a problem that the rotation shaft 53 cannot rotate smoothly.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is possible to secure an oil film even when a rotating shaft receives an external force, and to always realize a good fluid lubrication state. It is to provide a bearing that can be used.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a cylindrical portion in which an inner peripheral surface of a bearing hole for supporting a rotating shaft has an inner diameter constant in an axial direction. And an opening formed on at least one side of the cylindrical portion and having an inner diameter that expands toward the end, wherein the opening is expanded a plurality of times toward the end or The gist is to provide a variable opening which is changed continuously.

According to a second aspect of the present invention, in the bearing according to the first aspect, the variable opening for changing the inclination expanding toward the end a plurality of times is constituted by a plurality of tapered portions, and When the axis is inclined with respect to the cylindrical portion, at least the tapered portion close to the cylindrical portion can be abutted, so that the tapered portion farthest from the cylindrical portion is not abutted, so that the tapered portion closer to the cylindrical portion The gist of the present invention is to reduce the inclination of the expansion.

According to a third aspect of the present invention, in the bearing according to the first aspect, the variable opening for continuously changing the inclination that expands toward the end portion has a structure in which the rotation shaft is positioned relative to the cylindrical portion. The gist of the present invention is that the cross-sectional shape in the axial direction is a curved surface so as to be able to contact at least a portion near the cylindrical portion when inclining, and not to contact a portion farthest from the cylindrical portion.

According to a fourth aspect of the present invention, in the bearing according to any one of the first to third aspects, the bearing is a porous oil-impregnated bearing, and an inner peripheral surface of the bearing hole of the oil-impregnated bearing is provided. The gist of the present invention is that a hole is crushed to form a crushed portion having a dense surface.

According to a fifth aspect of the present invention, in the bearing of the fourth aspect, the crushed portion is formed to have a band shape over the cylindrical portion and the variable opening.

(Operation) Therefore, according to the first aspect of the present invention, the inner peripheral surface of the bearing hole for supporting the rotating shaft has a cylindrical portion whose inner diameter is constant in the axial direction, and at least one of the cylindrical portion. An opening formed on one side and having an inner diameter that expands toward an end, wherein the opening is formed such that the inclination that expands toward the end is changed a plurality of times or continuously. Since the rotating shaft is inclined by an external force and inclined at an angle with respect to the axis of the cylindrical portion, the misalignment of the rotating shaft is absorbed by the variable opening, and the rotating shaft is always in contact with the bearing. Approximate contact can be made with the surface.

According to the second aspect of the present invention, when the rotating shaft is inclined by an external force and inclined at an angle with respect to the axis of the cylindrical portion, the misalignment of the axis of the rotating shaft is absorbed by each tapered portion, and The rotation shaft can always contact the tapered portion near the cylindrical portion approximately in a plane.

According to the third aspect of the invention, when the rotating shaft is inclined by an external force and inclined at an angle with respect to the axis of the cylindrical portion, the deviation of the axis of the rotating shaft is absorbed by the variable opening having a curved surface. At the same time, the rotating shaft can always approximately contact the variable opening which is at least a curved surface close to the cylindrical portion.

According to the fourth aspect of the present invention, since the rotating shaft can always contact the inner peripheral surface of the bearing hole approximately in a plane, the rotating shaft is provided on the rotating shaft and the inner peripheral surface. The oil film formed between the crushed portions is not cut.

According to the fifth aspect of the present invention, even when the rotating shaft is tilted by an external force and rotates in contact with the variable opening, the rotating shaft always rotates smoothly via the oil film formed in the variable opening. be able to.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is embodied in a small motor with a speed reducer for an automobile will be described below with reference to FIGS.

As shown in FIG. 1, a housing 1 of a small motor with a speed reducer is integrally formed with a motor 2, and a rotating shaft 3 is supported by an oil-impregnated bearing 4. The oil-impregnated bearing 4 is inserted into a mounting hole 5 provided in the housing 1. A worm 6 is connected to the tip of the rotating shaft 3, and the worm 6 is meshed with a worm wheel 7 rotatably supported on the housing 1. Therefore, when the motor 2 rotates, the worm wheel 7 rotates at a lower rotation speed than the motor 2.

The oil-impregnated bearing 4 is formed of a porous sintered alloy having a large number of holes (not shown). Each hole is filled with lubricating oil. As shown in FIGS. 2 and 3, the oil-impregnated bearing 4 is formed in a substantially cylindrical shape, and a bearing hole 8 penetrates in the axial direction. The inner peripheral surface 9 of the bearing hole 8 has a cylindrical portion 1 whose inner diameter is constant in the axial direction.
0 and variable openings M which are provided at both ends of the cylindrical portion 10 and whose inner diameter increases as the distance from the cylindrical portion 10 increases in the axial direction. A plurality of (three in this embodiment, three in each case) first to third variable openings M are provided.
It is composed of tapered portions M1, M2, M3. In addition, as shown in FIG.
The taper angles θ1 to θ3 of the first to third tapered portions M1 to M3 gradually increase outward from the tapered portion M1. That is, the taper angle of the first taper portion M1 is θ1, the taper angle of the second taper portion M2 is θ2,
If the taper angle of the third tapered portion M3 is θ3, then θ1 <
The relationship of θ2 <θ3 is satisfied. In other words, the oil-impregnated bearing 4 of the present embodiment has the tapered portion 58 at the angle θa of the conventional bearing 51 shown in FIG. 11 corresponding to the third tapered portion 58 at the angle θ3 (= θa). A first tapered portion M1 having an angle θ1 and a second tapered portion M2 having an angle θ2 are formed between the first tapered portion M1 and the portion 58.

In order to smoothly incline from the cylindrical portion 10 to the first to third tapered portions M1 to M3, a boundary portion between the cylindrical portion 10 and the first tapered portion M1, a first tapered portion M1
The boundary between the first and second tapered portions M2 and the boundary between the second and third tapered portions M2 and M3 are finished to be curved surfaces.

On the inner peripheral surface 9 of the bearing hole 8, there is formed a crushed portion 11 in which the hole is crushed and the surface is dense. As shown in FIG. 4, the shape of the crushed portion 11 is such that the oil-impregnated bearing 4 becomes a belt-like shape when it is cut and deployed in the axial direction.

Further, in the present embodiment, the formation position of the closed portion 11 in the circumferential direction of the inner peripheral surface 9 of the bearing hole 8 is as follows. FIG. 5 is a sectional view taken along line AA in FIG. In FIG. 5, the center line P is shifted from the lowermost position Q of the cylindrical portion 10 in the counter-rotating direction of the rotating shaft 3 (counterclockwise direction in the drawing), and the rotation of the closed portion 11 in the cylindrical portion 10 is performed. The end of the shaft 3 in the rotation direction (clockwise direction in the figure) is formed so as to be slightly located on the rotation direction side of the rotation shaft 3 from the lowermost position Q of the cylindrical portion 10.

Next, the oil-impregnated bearing 4 constructed as described above
Will be described. (1) In the present embodiment, the inner peripheral surface 9 of the bearing hole 8 includes a cylindrical portion 10 having a constant inner diameter in the axial direction, and a cylindrical portion 1.
The variable opening portion M includes first to third tapered portions M1 to M3 which are provided at both ends of the cylindrical portion 10 and whose inner diameter increases as the distance from the cylindrical portion 10 increases in the axial direction. Moreover, each boundary between the cylindrical portion 10 and the first to third tapered portions M1 to M3 was finished to be a curved surface.

Accordingly, the rotating shaft 3 is tilted by an external force, and the rotating shaft 3 has an angle θ1 with respect to the axis L0 of the cylindrical portion 10.
When tilted, the rotating shaft 3 and the bearing 4 come into contact with each other at the tapered portion M1. In this case, the load of the rotating shaft 3 is received on the surface. In this case, since the contact surface is crushed, the strength of the oil film is increased, and the oil film is smoothly supported without rotating metal contact. The cylindrical portion 10 and the first tapered portion M1
And the rotating shaft 3 has a first tapered portion M1 without local metal contact.
Is smoothly supported in rotation. Further, when the rotating shaft 3 is inclined at an angle θ2 with respect to the axis L0 of the cylindrical portion 10, the boundary between the first tapered portion M1 and the second tapered portion M2 is finished to a curved surface. It is smoothly rotated and supported on the surface of the second tapered portion M2 without local metal contact. Furthermore, the rotation axis 3 is the axis L of the cylindrical portion 10.
When the angle θ3 is inclined with respect to 0, since the boundary between the second tapered portion M2 and the third tapered portion M3 is finished to a curved surface, the rotating shaft 3 does not locally come into metallic contact with the third tapered portion. It is smoothly rotated and supported on the surface of M3.

When the maximum inclination of the rotating shaft 3 with respect to the oil-impregnated bearing 4 is larger than the taper angle θ2 of the second tapered portion M2 and smaller than the angle θ3 of the third tapered portion M3, the rotating shaft 3 is moved up to the maximum inclination. When it is tilted, it comes into sliding contact at the boundary between the second tapered portion M2 and the third tapered portion M3 finished into a curved surface, and there is no local metal contact unlike the conventional case. That is, the rotating shaft 3 always comes into contact with the bearing 4 approximately in a plane. Therefore, the rotating shaft 3 rotates smoothly inside the oil-impregnated bearing 4 and the assembly must have extremely strict tolerances in order to prevent the oil-impregnated bearing 4 from tilting with respect to the rotating shaft 3 due to assembly variations when assembling the motor. Is reduced.

(2) In this embodiment, the crushed portion 11 is formed on the inner peripheral surface 9 of the bearing hole 8. And the crushed part 1
Reference numeral 1 denotes a position where the center line P is shifted from the lowermost position Q of the cylindrical portion 10 in the anti-rotation direction of the rotating shaft 3 and the cylindrical portion 1
0, the end of the crushed portion 11 in the rotation direction is the cylindrical portion 10.
Is formed on the rotation direction side of the rotating shaft 3 from the lowermost position Q of the above. Therefore, this hydraulic pressure distribution can be maximized in the rotation upstream portion of the minimum gap in the gap formed by the bearing 4 and the rotating shaft 3, and a good fluid lubrication state can be realized.

Moreover, the crushed portion 11 is formed to have a band shape over the first to third tapered portions M1 to M3. Therefore, even when the rotating shaft 3 is rotating in a state of being inclined with respect to the axis L0 of the cylindrical portion 10, the rotating shaft 3 is always the first to the first.
It is possible to smoothly rotate via the oil film formed on the third tapered portions M1 to M3.

The above embodiment is not limited to the above, but may be modified as follows. In the above embodiment, the first to third portions are provided at both ends of the cylindrical portion 10.
Although the variable opening portion M including the tapered portions M1 to M3 is formed, a fourth tapered portion M4 is further formed outside the third tapered portion M3 as shown in FIG. And, the taper angle θ4 of the fourth tapered portion M4 is set so that the rotating shaft 3
Is set so that it does not come into contact with the surface of the fourth tapered portion M4 even if is inclined to the maximum. Further, the respective taper angles θ1 to θ3 of the first to third tapered portions M1 to M3 are set to θ1 <θ2 of the above-described embodiment.
<In the range where the relationship of θ3 holds, for example, θ2 =
It may be implemented such that 2.multidot..theta.1, .theta.3 = 3.multidot..theta.1. Also in this case, the first to third tapered portions M1 to M3 have the same functions and effects as those of the above embodiment.
Further, since the fourth tapered portion M4 forms an oil reservoir, the surface tension of the lubricating oil overflowing into the clearance does not decrease. As a result, it is possible to prevent the lubricating oil from overflowing from the bearing hole 8.

The first to fourth tapered portions M shown in FIG.
1 and M4, the first and second variable openings M
The angles θ1 and θ2 of the tapered portions M1 and M2 may be set to θ1 = θ2, and the angle θ3 of the third tapered portion M3 may be set to θ3 = 2 · θ1. Also in this case, the first to first
The fourth tapered portions M1 to M4 have the same functions and effects as described above.

The first to third tapered portions M1 to M shown in FIG.
3 and the first through fourth variable openings M shown in FIG.
Although the variable opening M formed by the tapered portions M1 to M4 has a left-right symmetric shape, the variable opening M may be left-right asymmetric. In this case, the same operation and effect as those of the above embodiment can be obtained.

In the above embodiment, the boundary portion between the cylindrical portion 10 and the first tapered portion M1 and the first to third tapered portions M1 to M1
Although each boundary portion of M3 is finished to a curved surface, it may be omitted.

In the above embodiment, the variable openings M are formed on both the left and right sides, but may be formed on only one of them. In this case, the same operation and effect as in the above embodiment can be obtained. The variable opening M is a first to third tapered portion M shown in FIG.
1 to M3 have a straight sectional shape in the axial direction except for the boundary portion. This may be performed by forming the variable opening M having a curved cross section in the axial direction without forming the first to third tapered portions M1 to M3. Of course, the variable opening M may be formed only on one side of the bearing 4 as shown in FIG.

The crushed portion 11 has a band shape, but the shape is not limited to this. For example, the crushed portion 11 may be formed in a shape other than the band shape, such as a polygon, a circle, an ellipse, or an irregular shape. Alternatively, the shape may be tapered toward the end. In this case, the same operation and effect as those of the above embodiment can be obtained.

The oil-impregnated bearing 4 of each of the above embodiments is made of a porous sintered alloy, but is not limited to a sintered alloy, and may be made of, for example, a sintered ceramic. In this case, the same effect as in the above embodiment can be obtained.

In the above embodiment, the present invention is embodied in a small motor with a reducer for an automobile, and the present invention is applied to a small motor other than a small motor with a reducer for an automobile or other rotating equipment. It may be implemented in a form. In this case, the same effect as in the above embodiment can be obtained.

[0036]

As described in detail above, according to the first to sixth aspects of the present invention, it is possible to secure an oil film even when the rotating shaft receives an external force, and to always realize a good fluid lubrication state. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a small motor with a reduction gear for an automobile using an oil-impregnated bearing of the present invention.

FIG. 2 is an axial sectional view of the oil-impregnated bearing.

FIG. 3 is an enlarged sectional view of a main part of the oil-impregnated bearing.

FIG. 4 is a development view of an inner peripheral surface of a bearing hole of the oil-impregnated bearing.

FIG. 5 is a radial sectional view of the oil-impregnated bearing.

FIG. 6 is an enlarged sectional view of a main part of another example of the oil-impregnated bearing.

FIG. 7 is a cross-sectional view of another example of an oil-impregnated bearing.

FIG. 8 is a schematic radial view of a conventional oil-impregnated bearing.

FIG. 9 is an axial schematic view of a conventional oil-impregnated bearing.

FIG. 10 is a hydraulic pressure distribution diagram in a conventional oil-impregnated bearing.

FIG. 11 is a schematic view of a rotating shaft in a conventional oil-impregnated bearing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor housing, 2 ... Motor, 3 ... Rotating shaft, 4 ...
Oil-impregnated bearings, 6 worm, 7 worm wheel, 8
Bearing hole, 9: inner peripheral surface, 10: cylindrical portion, 11: crushed portion,
M: variable opening, M1 to M4: first to fourth tapered parts, P
... Center line of the crushed part, θ1 to θ4 ... Taper angle, L0 ...
Center axis of bearing, L1 ... Center axis of rotating shaft.

Claims (5)

[Claims] An inner peripheral surface (9) of a bearing hole (8) for supporting a rotary shaft (3) has a cylindrical portion (10) having a constant inner diameter in the axial direction, and a cylindrical portion (10). An opening formed on at least one side and having an inner diameter expanding toward an end, wherein the opening is inclined toward the end (θ1 to θ
Variable opening (M) that changes 3) several times or continuously
A bearing characterized in that: 2. The bearing according to claim 1, wherein the variable opening (M) that changes the inclination (θ1 to θ3) expanding toward the end a plurality of times includes a plurality of tapered portions (M1 to M1).
M3, M4), and when the rotating shaft (3) is inclined with respect to the cylindrical portion (10), at least the cylindrical portion (1)
0) can be in contact with the tapered portions (M1 and M2), and the tapered portions (M3 and M4) farthest from the cylindrical portion (10).
So that the taper portions (M1 to M3, M4) closer to the cylindrical portion (10) expand so that they do not come into contact with each other.
A bearing characterized in that 3) is reduced. 3. The bearing according to claim 1, wherein the variable opening (M) for continuously changing the inclination (θ1 to θ3) expanding toward the end has a cylindrical shape. When inclined with respect to the cylindrical portion (10), at least a portion close to the cylindrical portion (10) can be brought into contact with the cylindrical portion (1).
A bearing characterized in that the cross-sectional shape in the axial direction is a curved surface so as not to come into contact with the portion farthest from 0). 4. The bearing according to claim 1, wherein the bearing is a porous oil-impregnated bearing (4), and the inner circumference of the bearing hole (8) of the oil-impregnated bearing (4). A bearing characterized in that the surface (9) is formed with a crushed portion (11) in which holes are crushed and the surface is densely formed. 5. The bearing according to claim 4, wherein the crushed portion (11) is formed in a band shape over the cylindrical portion (10) and the variable opening (M). Bearing.