JPH1182487A - Porous bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a sufficient lubricating function and the generation of effective dynamic pressure in both of a thrust sliding surface and a radial sliding surface. SOLUTION: A chamfered part 3 is formed by chamfering the opening edge of a shaft hole from an end surface 10 for receiving a thrust load to an inner peripheral surface 20 for receiving a radial load. At least three or more groove- like thrust recessed parts 11 are radially formed in the end surface 10 so as to be extended obliquely from an outer peripheral side to the inner peripheral side toward the rotational direction of a shaft 8 and, on the other hand, in a position corresponding to the thrust recessed part 11 of the inner peripheral surface 20, a radial recessed part 21 is formed such that its peripheral edge is opened toward the chamfered part 3. Lubricating oil flowing out from the thrust recessed part 11 to the chamfered part 3 is merged with lubricating oil flowing out from the radial recessed part 21 and, by maintaining the pressure of lubricating oil also in the vicinity of the opening of the shaft hole 2, dynamic pressure generation is assisted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous bearing suitable for supporting a shaft rotating at a relatively high speed, such as a bearing for a spindle motor, with high precision.

[0002]

2. Description of the Related Art As a bearing made of a porous material, a sintered oil-impregnated bearing is generally used. In this sintered oil-impregnated bearing, the lubricating oil contained oozes out on the inner peripheral surface, which is the sliding surface in the radial direction, and an oil film is formed, thereby reducing frictional resistance and suppressing noise and vibration. It is. Further, there is a type in which a groove or a concave portion is provided on an inner peripheral surface to generate dynamic pressure in lubricating oil, thereby increasing a supporting force against a radial load and increasing rigidity as a bearing. By the way, in the case of a thrust bearing in which the thrust load is carried by receiving the shaft flange at the end face together with the radial load, lubricating oil is supplied to the end face which is the thrust sliding surface with the flange,
It has been conventionally difficult to generate dynamic pressure by the supplied lubricating oil as compared with the case of the inner peripheral surface.

[0003] To overcome this, there is the following prior art. A wave-shaped ridge having a plurality of peaks is formed on the end face receiving the thrust load along the circumferential direction and the radial direction, and the thrust load is supported by the plurality of peaks (Japanese Patent Laid-Open No. 1-1121). . According to this sintered oil-impregnated bearing, a positive pressure and a negative pressure are generated in the lubricating oil due to the height difference of the ridge,
As a result, lubricating oil is supplied to the thrust sliding surface, and a dynamic pressure is generated. A plurality of linear concave portions having a slanted bottom surface are formed on the end surface, the concave portions serve as a lubricating oil supply portion, and wedge-shaped gaps formed by the concave portions effectively generate dynamic pressure. JP-A-57-63121). Although not a sintered oil-impregnated bearing, a plurality of concave portions having a bottom surface inclined in two steps are formed on the end surface so that dynamic pressure can be effectively generated (Japanese Patent Publication No. 63-33010). While forming a plurality of grooves radially on the end face,
Make the density of the bottom of those grooves higher than the density of other parts,
Leakage of the lubricating oil accumulated in the groove is suppressed, and the lubricating oil supply efficiency is improved (Japanese Patent Laid-Open No. 50-35552).

[0004] The foregoing aims at providing an effective supply of lubricating oil and generation of dynamic pressure by providing a concave portion or a groove on an end face receiving a thrust load. In addition to the above, there are sintered oil-impregnated bearings that are not thrust bearings, but the following are examples of grooves provided on the end face. A plurality of grooves were formed radially on the end face, and the opening edge facing the end face of the shaft hole was chamfered relatively large (Japanese Patent Laid-Open No. 58-623). In this case, the lubricating oil flowing out from between the shaft and the inner peripheral surface is guided from the opening edge to the outer peripheral surface through the groove, thereby suppressing the scattering of the lubricating oil and ensuring that the lubricating oil flows to the bearing itself. It is expected to have the effect of being recovered and having a long life.

[0005]

The above prior arts have the following problems. The wavy ridges are formed when the green compact is formed or when the sintered body is recompressed. In any case, the production of the mold on which the ridges are to be formed depends on accuracy and cost. Difficult. Also, since the shaft flange comes into point contact with the top of the wavy ridge, the limit of the thrust load resistance is relatively low, and it takes some time until stable sliding characteristics are exhibited. . Since the concave portion is linear and the bottom surface of the concave portion is a two-dimensional plane, the rotational speed of the shaft and the position of the concave portion at which effective dynamic pressure can be generated are uniquely determined, and the rotational speed of the shaft and the concave portion are determined. Is specified in a narrow range. Therefore, it is difficult to cope with the case where the range of the number of rotations of the shaft is wide, and it is inferior in versatility and durability. In addition, the supply of lubricating oil to the end face is expected to be insufficient due to a large expectation of a spring due to frictional thermal expansion from the radial sliding face or a simple leak from the sliding face. The range of the number of rotations of the shaft and the position of the concave portion in which an effective dynamic pressure can be generated is wider than in the above case, but similarly, there is a difficulty in supplying the lubricating oil to the end face. It has the same problems as the supply of lubricating oil to the end face, and furthermore, it is not satisfactory to supply the lubricating oil to the end face in the initial stage of operation and maintain the stored state of the lubricating oil once supplied to the recess. It is assumed that Therefore, stable sliding characteristics and high durability cannot be expected. The main purpose is to suppress the scattering of the lubricating oil and to surely collect the lubricating oil. No consideration is given to the sliding characteristics when applied as a thrust bearing.

Accordingly, the present invention provides a porous bearing which achieves sufficient bearing performance by achieving sufficient lubrication and effective dynamic pressure generation on both the end face receiving a thrust load and the inner peripheral face receiving a radial load. It is intended to be.

[0007]

SUMMARY OF THE INVENTION The present invention is a substantially cylindrical porous bearing containing a fluid lubricant and having an end face receiving a thrust load and an inner peripheral face receiving a radial load from a shaft to be supported. The opening edge of the shaft hole extending from the end face to the inner peripheral surface is chamfered to form a chamfered portion, and a plurality of thrusts extending from the outer peripheral side to the inner peripheral side toward the rotation direction of the shaft are provided on the end face. A concave portion is formed radially, and at a position corresponding to the thrust concave portion on the inner peripheral surface,
It is characterized in that a radial concave part whose peripheral edge is open to the chamfered part is formed.

According to the bearing having the above structure, the thrust concave portion extends from the outer peripheral side to the inner peripheral side in the direction of rotation of the shaft.
Movement or scattering to the outer peripheral side due to the centrifugal force of the shaft is suppressed, and conversely, the pressure increases at the inner peripheral end. Thereby, a dynamic pressure is generated on the end face with the rotation of the shaft. On the other hand, also on the inner peripheral surface, a dynamic pressure is generated by an increase in the pressure of the lubricant in the radial concave portion. As described above, dynamic pressure is generated on both the thrust sliding surface and the radial sliding surface. Here, the lubricant in the radial concave portion has an opening side due to the concave portion being opened to the chamfered portion. It tends to flow out to the chamfer at low pressure. Also,
Part of the lubricant that has been subjected to the dynamic pressure in the thrust recess flows out of the thrust recess, and further flows into the low-pressure radial recess through the chamfered portion through the opening. Then, the lubricant flowing out of the thrust concave portion and the lubricant flowing out of the radial concave portion merge in a gap formed between the chamfered portion and the shaft or near the opening of the radial concave portion facing the chamfered portion. Due to the joining of the lubricant, the low pressure state at the end of the radial recess on the opening side is eliminated, and a certain level of pressure is secured, or a new pressure equivalent to a desired dynamic pressure is generated in some cases. For this reason, on the radial sliding surface, the supply of the lubricant and the generation of the dynamic pressure are uniformly and sufficiently performed over the entire length in the axial direction in which the radial recess is formed. Supply and dynamic pressure generation are sufficient. As a result, the lubricating action of both the thrust sliding surface and the radial sliding surface and the rigidity for supporting the shaft are improved, and the performance as a thrust bearing is enhanced.

In the above structure, the thrust recess is formed
A thrust recess A whose depth becomes deeper toward the inner circumference side and a thrust recess B whose depth becomes deeper toward the outer circumference side, and these are arranged substantially alternately in the circumferential direction, When the radial recess is formed at a position corresponding to the thrust recess A and / or the thrust recess B on the inner peripheral surface, the above operation is further clarified. That is, the lubricant that flows into the deep thrust recess A on the inner peripheral side with the rotation of the shaft is easily stored in the deep inner peripheral side, while the lubricant that flows into the deep thrust concave B on the outer peripheral side has a wedge-like shape. The gap concentrates on the inner peripheral side formed in the direction of rotation of the shaft, thereby generating a large dynamic pressure. In other words, the thrust recess A mainly supplies the lubricant, and the thrust recess B mainly generates the dynamic pressure. The lubricant supplied to the thrust recess A flows out to the thrust sliding surface and also flows into the chamfered portion. Also, the thrust recess B
Similarly, the lubricant responsible for generating the dynamic pressure flows out to the thrust sliding surface and also flows into the chamfered portion. The lubricant that has flowed into the chamfer merges with the lubricating oil from the radial recess formed corresponding to the thrust recess A and / or the thrust recess B, where a new dynamic pressure is generated. As a result, on the thrust sliding surface, the supply of the lubricating oil and the generation of the dynamic pressure are performed in a well-balanced and sufficient manner, and the dynamic pressure is also effectively generated on the radial sliding surface.

The number of the thrust recesses and the number of the radial recesses is preferably at least 3 or more, more preferably 3 or more, since the support state of the shaft becomes unstable if two. This is because the synchronization of various vibration frequencies generated with the rotation of the shaft is effectively canceled by at least one recess, and as a result, noise and vibration due to resonance are effectively reduced. Is suppressed.

Further, the thrust recess extends from the outer peripheral side toward the inner peripheral side in the direction of rotation of the shaft, that is, is formed obliquely at a certain angle with respect to a tangent line of the outer periphery of the bearing. . The inventor of the present invention set the inclination angle variously and examined the supply amount of the lubricant to the thrust recess and the degree of the generated dynamic pressure. Found that it is preferable to set it to. That is, if the angle is less than 5 °, the supply of the lubricant is insufficient, and it is assumed that this is caused by an increase in the pressure loss due to the resistance of the lubricating oil to flowing into the thrust recess. On the other hand, if the angle exceeds 45 °, the supply of lubricating oil to the thrust recess and the generation of dynamic pressure are insufficient. It was thought that the desired action could not be obtained. Therefore, it is preferable that the angle of the thrust recess is set in the range of 5 to 45 degrees with respect to the tangent line on the outer periphery. Note that the thrust recess is not limited to a linear shape, and may be, for example, an arc shape that protrudes outward. In this case, the tangent at the center of the thrust recess is 5 to 4 with respect to the tangent at the outer periphery.
It is formed to have an angle of 5 °.

Further, according to the study of the present inventors, it has been found that when the depth of the thrust recess is set in the range of 5 to 100 μm, the supply of the lubricant and the generation of the dynamic pressure are effectively performed. Was. This is because when the thickness is less than 5 μm, the difference in oil pressure between the lubricating oil supplied to the thrust recess and the dynamic pressure generating portion becomes small. This is assumed as a reason, and in any case, generation of an effective dynamic pressure cannot be expected. Further, the end face receiving a thrust load is:
By forming the tapered shape to be convex on the inner peripheral side, the frictional resistance generated on the end face is further reduced, and noise and vibration are suppressed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view illustrating a state in which a shaft 8 is rotatably supported by a cylindrical sintered oil-impregnated bearing (porous bearing: hereinafter, simply referred to as a bearing) 1 according to the first embodiment.
FIG. 2 is a vertical perspective view of the bearing 1. The bearing 1 is in this case pressed into the housing 9. As shown in FIG. 1, the bearing 1 receives a thrust load from a flange 8 a formed on the shaft 8 on one end face 10, and receives a radial load from the shaft 8 inserted into the shaft hole 2 on the inner peripheral face 20. I am going to receive it. As shown in FIGS. 1 and 4, the opening edge of the shaft hole 2 on the end face 10 side is chamfered to form a chamfered portion 3.

As shown in FIG. 2, a plurality of three or more groove-shaped thrust recesses 11 are radially formed on the end face 10 of the bearing 1 at equal intervals in the circumferential direction. The number of the thrust recesses 11 is preferably at least three or more, more preferably three or more prime numbers, because the support state of the shaft 8 becomes unstable if two. This is because at least one thrust recess 11 can reliably cancel the synchronization of various vibration frequencies generated with the rotation of the shaft 8, and therefore, noise and vibration due to resonance can be achieved. Is effectively suppressed.

The thrust recess 11 is linear, and extends obliquely from the outer peripheral side to the inner peripheral side in the direction of rotation of the shaft 8 indicated by the arrow A in FIG. The angle of inclination is preferably set in the range of 5 to 45 degrees with respect to the tangent line of the outer periphery. In addition, the thrust recess 11 is not limited to a linear shape,
For example, the shape may be an arc that protrudes outward. In that case, the tangent at the center is 5 to 45
It is formed to have an angle of ゜. When the angle of the thrust recess 11 is set to less than 5 °, the pressure loss due to the resistance of the lubricating oil to flow into the thrust recess 11 increases and the supply of the lubricant becomes insufficient. This is based on the reason that the length of the thrust recess 11 is short and is too steep with respect to the tangent line on the outer periphery, so that lubricating oil is not sufficiently supplied to the thrust recess 11 and dynamic pressure is not sufficiently generated.

Both ends of the thrust recess 11 are not open to the outer peripheral surface and the chamfered portion 3 but are closed in the end surface 10. The cross-sectional shape along the length direction and the width direction of the thrust recess 11 is arbitrary, and is formed, for example, in a rectangular shape, a semicircular arc shape, a semielliptical shape, or a triangular shape. Here, the depth of the deepest part of the thrust recess 11 is 5 to
When the thickness is set to 100 μm, good sliding characteristics can be obtained, which is preferable. If the thickness is less than 5 μm, the difference in oil pressure between the lubricating oil supplied to the thrust recess 11 and the dynamic pressure generating portion is small, and sufficient dynamic pressure is not generated. This is because a sufficient supply of water cannot always be obtained, and dynamic pressure hardly occurs.

On the other hand, as shown in FIG. 2, trapezoidal radial recesses 21 are formed in the inner peripheral surface 20 of the bearing 1 at positions corresponding to every other thrust recess 11. I have. These radial recesses 21 have a constant width along the circumferential direction along the axial direction, and the upper edge (the edge on the side of the end face 10) in FIG. The lower peripheral edge extends obliquely downward (inward of the shaft hole 2) toward the rotation direction of the shaft 8. FIG. 3 shows a cross-sectional shape of the radial recess 21 along the circumferential direction. As shown in FIG.
The bottom surface of 1 has a tapered shape in which the end opposite to the rotation direction A of the shaft 8 is deepest and gradually becomes shallower from the deepest part toward the rotation direction of the shaft 8.
A wedge-shaped gap is formed between the shaft 8 and the shaft 8. The number of the radial recesses 21 is preferably a prime number of three or more for the same reason as in the case of the thrust recess 11.

Next, the operation of the bearing will be described. Axis 8
Rotates, the lubricating oil supplied from the bearing 1 itself between the end face 10 and the flange 8a flows into the thrust recess 11 on the end face 10 receiving the thrust load. Further, the lubricating oil flowing out from between the inner peripheral surface 20 and the shaft 8 flows between the end face 10 and the flange 8a through the chamfered portion 3, so that the lubricating oil is supplied to the thrust recess 11. Since the thrust concave portion 11 extends from the outer peripheral side to the inner peripheral side in the direction of rotation of the shaft 8, the movement or scattering of the lubricating oil toward the outer peripheral side due to centrifugal force is suppressed. And the pressure rises, and a dynamic pressure is generated in this portion. Thus, on the thrust sliding surface, the lubricating oil supplied to the thrust recess 11 is supplied to the flange 8.
Since the storage state is ensured without being affected by the centrifugal force a and the dynamic pressure is reliably generated, the sliding characteristics are improved.

On the other hand, on the inner peripheral surface 20 that receives the radial load, the lubricating oil supplied from the bearing 1 itself between the inner peripheral surface 20 and the shaft 8 flows into the radial recess 21. Since the end of the radial recess 21 on the rotation direction side of the shaft 8 forms a wedge-shaped gap, the lubricating oil concentrates on the end and the pressure increases, and dynamic pressure is generated. As described above, on the radial sliding surface, the lubricating oil is supplied to the radial recess 21 and a large dynamic pressure is generated, so that the sliding characteristics are improved. In this case, the radial concave portion 21 is formed such that the inner peripheral edge of the shaft hole 2 (the lower peripheral edge in FIG. 2) extends obliquely inward toward the rotation direction of the shaft 8. In this case, the wedge effect increases, and a larger dynamic pressure can be obtained.

The lubricating oil in the radial recess 21 tends to flow out to the chamfer 3 at a low pressure on the opening side because the recess 21 is open to the chamfer 3. In addition, a part of the lubricating oil that has been subjected to the dynamic pressure in the thrust recess 11 flows out of the thrust recess 11 and further flows into the low-pressure radial recess 21 through the chamfer 3 from the opening. Therefore, as shown in FIG. 4, the lubricating oil flowing out of the thrust concave portion 11 and the lubricating oil flowing out of the radial concave portion 21 form a gap formed by the chamfered portion 3, the shaft 8 and the flange 8 a, or a chamfered portion. 3 join near the opening of the radial recess 21. As a result, the low pressure state at the end of the radial recess 21 on the opening side is eliminated, and a certain level of pressure is secured, or a new pressure equivalent to a desired dynamic pressure is generated in some cases. Accordingly, on the radial sliding surface, the supply of the lubricating oil and the generation of the dynamic pressure are uniformly and sufficiently performed over the entire length in the axial direction in which the radial concave portion 21 is formed, and also on the thrust sliding surface, the lubricating oil is formed as described above. Supply and dynamic pressure generation are sufficient. As a result, the lubricating action of both the thrust sliding surface and the radial sliding surface and the rigidity for supporting the shaft 8 are improved, and the performance as a thrust bearing is enhanced.

Next, second and third embodiments of the present invention will be described. In the drawings referred to in the description of these embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

(2) Second Embodiment A second embodiment of the present invention will be described with reference to FIG. A groove-shaped radial recess 22 is formed on the inner peripheral surface 20 of the bearing 5 of the second embodiment shown in FIG. 5 so as to correspond to each of the thrust recesses 11 formed on the end face 10. These radial recesses 22 only open at the upper end edges in FIG. 5 to the chamfered portion 3 and extend obliquely from the upper ends in the direction opposite to the rotation direction A of the shaft. Radial recess 22
The cross-sectional shape along the circumferential direction is the first shape shown in FIG.
This is the same as the radial recess 21 of the embodiment.

According to the bearing 5, the radial recess 22
Extends obliquely in the rotational direction of the shaft from the inside of the shaft hole 2 toward the end face 10, the lubricating oil in the radial recess 22 easily flows in the direction of the end face 10, and the lubricating oil flowing from the thrust recess 11 The combined flow rate with oil increases.
For this reason, a dynamic pressure near the opening of the inner peripheral surface 20 is easily generated and the dynamic pressure increases, so that the rigidity for supporting the shaft is improved.

(3) Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. 6 and 7. On the end face 10 of the bearing 6 of the third embodiment shown in FIG. 6, a plurality of groove-shaped thrust recesses 13A and a plurality of groove-shaped thrust recesses 13B are formed alternately in the circumferential direction and at equal intervals. I have. These thrust recesses 13
A and 13B are arc-shaped convex on the outer peripheral side, and are formed such that the tangent at the center thereof is at an angle of 5 to 45 ° with respect to the tangent on the outer periphery. The difference between the thrust recesses 13A and 13B lies in the cross-sectional shape thereof.
As shown in FIG. 7A, the depth increases toward the inner circumference (IN) side. On the contrary, as shown in FIG.
The depth increases toward the T) side.

On the other hand, as shown in FIG. 6, a plurality of right-angled isosceles triangular radial recesses 2 are formed on the inner peripheral surface 20 of the bearing 6.
3 are formed. The radial concave portion 23 extends obliquely with respect to the rotation direction A of the shaft as the bottom side goes from the chamfered portion 3 to the inside of the shaft hole 2. , The other extending parallel to the axial direction. The opening edge to the chamfered portion 3 extends obliquely from the outer peripheral side to the inner peripheral side of the chamfered portion 3 toward the rotation direction of the shaft, and the opening side where the opening edge and the bottom side intersect. Is in proximity to the thrust recess 13A. In this way, the radial concave portion 2 in which the acute angle portion 23a on the opening side is close to the thrust concave portion 13A
3 are formed corresponding to each thrust recess 13A. Further, like the radial recess 21 of the first embodiment shown in FIG. 3, the cross-sectional shape of the radial recess 23 along the circumferential direction has a tapered shape that gradually becomes shallower in the rotation direction of the shaft. Has become.

According to the bearing 6, the lubricating oil that has flowed into the deep thrust recess 13A on the inner peripheral side with the rotation of the shaft is easily stored in the deep inner peripheral side, while the lubricating oil flows into the deep thrust recess 13B on the outer peripheral side. Lubricating oil concentrates on the inner peripheral side where a wedge-shaped gap is formed in the rotation direction of the shaft,
This generates a large dynamic pressure. That is, the supply of the lubricating oil is mainly performed by the thrust recess 13A, and the thrust recess 1A is provided.
3B mainly generates dynamic pressure. The lubricating oil supplied to the thrust recess A13 flows out to the thrust sliding surface, and passes through the chamfered portion 3 to form an acute angle portion 23 on the opening side of the radial recess 23.
flows into a. Then, from the radial recess 23 to the end face 10
It merges with the lubricating oil flowing in the direction, where a new dynamic pressure is generated. As a result, on the thrust sliding surface, supply of lubricating oil and generation of dynamic pressure are performed in a well-balanced and sufficient manner. Be done effectively.

The radial recess 23 may be formed at a position corresponding to the thrust recess 13B whose depth becomes deeper toward the outer peripheral side. In this case, the lubricating oil flowing into the chamfered portion 3 after generating the dynamic pressure in the thrust recess 13 </ b> B merges with the lubricating oil flowing from the radial recess 23 toward the end face 10, and a new dynamic pressure is generated in the vicinity of the end face 10. Occurs and has the same effect as described above. Further, the radial recess 23 may be formed at a position corresponding to both the thrust recess 13A and the thrust recess 13B.

FIG. 8 shows a modification of the third embodiment. In this case, although the radial recesses 23 have the same shape, the bottom side is formed on the side of the shaft in the rotation direction A, and is orthogonal to each other. A right-angled portion 23b formed by the side portion is close to the thrust recess 13A.

In the present invention, the form of the thrust recess formed on the end face 10 and the form of the radial recess formed on the inner peripheral surface 20 are arbitrary. For example, as shown in FIG. 9, the thrust recess 14 may be open on the outer peripheral surface, and the radial recess 24 may be a rectangular shape that is long in the axial direction. FIG. 1 shows various modifications of the thrust recess 14.
0, and various modifications of the radial recess 24 are shown in FIG. The thrust recess 14 in FIG. 10A is formed in an elongated fan shape extending from the outer peripheral side to the inner peripheral side, and is opened on the outer peripheral surface. Further, the thrust recesses 14 and 14 in FIG. 10B are symmetrically spread in the circumferential direction toward the inner peripheral side around the radial line, and merge at the opening to the outer peripheral surface. The direction of rotation is forward / reverse (arrows A and B)
In either case, it is possible to respond. The thrust recess 14 in FIG. 10C has a fan shape extending from the inner peripheral side to the outer peripheral side, and is open to both the chamfered portion 3 and the outer peripheral surface. Each of the side wall portions connected to the end surface 10 is inclined from the bottom surface toward the rotation direction A of the shaft.
In this case, a wedge-shaped gap is formed at the end of the shaft in the rotation direction, so that large dynamic pressure is easily generated, and a negative pressure is generated at the end of the shaft opposite to the rotation direction to supply lubricating oil. Easy to be.

On the other hand, the radial recess 24 in FIG. 11A has a right-angled triangular shape, and its cross-sectional shape along the circumferential direction is such that the bottom, which is the deepest portion along the hypotenuse, is It has a triangular shape inclined to the opposite side in the rotation direction A of the shaft from the facing edge. By this cross-sectional shape, the supply of the lubricating oil and the generation of the dynamic pressure are effectively performed, similarly to the thrust recess 14 shown in FIG. The radial recess 24 in FIG. 11B has a rectangular shape that extends obliquely inward from the end face 10 side in the rotation direction A of the shaft, and its cross-sectional shape along the circumferential direction is shown in FIG. ) Is the same as the radial concave portion 24. The radial recess 24 in FIG. 11C has an isosceles triangle shape converging toward the inside of the shaft hole 2, and the cross-sectional shape along the circumferential direction is also an isosceles triangle shape. In the radial recess 24, similarly to the thrust recess 14 shown in FIG. 10B, it is possible to cope with both forward and reverse rotations of the shaft (arrows A and B).

The thrust recess 14 and the radial recess 2
For example, as shown in FIG. 12 (a), when both are groove-shaped, the innermost end of the radial recess 24 is located at the inner peripheral end of the thrust recess 14, as shown in FIG. Close to each other. The bottom surface of the radial recess 24 is shown in FIG.
In the case of a tapered shape as shown in FIG. 12, the deepest portion is also made to approach the inner peripheral end of the thrust recess 14 as shown in FIG. Further, as shown in FIG. 12C, when the bottom surfaces of the thrust recess 14 and the radial recess 24 are flat with a certain width, they are arranged so as to correspond to each other without shifting in the circumferential direction. In either case,
It is desirable that the lubricating oil flows from the thrust concave portion 14 toward the deepest portion of the radial concave portion 24 and exerts the above-described effective merging effect.

Further, in each of the above embodiments, the end face 10 on which the flange of the shaft slides is assumed to be flat, but may be tapered such that the inner peripheral side is convex as shown in FIG. . As shown in the figure, the thrust recess 14 formed in the end face 10 may be deeper toward the outer peripheral side as shown on the left side, and conversely, toward the inner peripheral side as shown on the right side. It may be deeper. In this case, the radial recess 24 of the inner peripheral surface 10 has the form shown in FIG. As described above, by forming the end face 10 in a tapered shape that protrudes inward, the contact area between the end face 10 and the flange 8a of the shaft 8 is reduced, the frictional resistance is further reduced, and noise and vibration are suppressed. It has the effect of being able to.

Although each of the above embodiments is a sintered oil-impregnated bearing, the present invention is not limited to the porous bearing, and may be made of a single material such as resin, ceramics, cermet or the like. A composite material in which two or more are combined may be used. Also, the lubricant contained is also determined according to the material, in addition to lubricating oil, water,
A fluid such as air is appropriately used.

[0034]

As described above, according to the porous bearing of the present invention, since the lubricant in the thrust recess merges with the lubricant flowing out of the radial recess through the chamfered portion, the lubricant in the radial recess is formed. Thus, a sufficient lubricating action and effective dynamic pressure generation can be achieved on both the thrust sliding surface and the radial sliding surface.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state where a shaft is supported by a bearing according to a first embodiment of the present invention.

FIG. 2 is a vertical perspective view of the bearing according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along a circumferential direction of a radial recess of the bearing according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining an operation of the bearing according to the first embodiment of the present invention.

FIG. 5 is a vertical perspective view of a bearing according to a second embodiment of the present invention.

FIG. 6 is a vertical perspective view of a bearing according to a third embodiment of the present invention.

FIG. 7A is a sectional view of one thrust recess of the bearing according to the third embodiment of the present invention, and FIG. 7B is a sectional view of the other thrust recess.

FIG. 8 is a vertical perspective view showing a modified example of the bearing according to the third embodiment of the present invention.

FIG. 9 is a longitudinal perspective view of a bearing to which a modified example of the thrust recess and the radial recess according to the present invention is applied.

FIG. 10 is a perspective view showing another modification of the thrust recess according to the present invention.

FIG. 11 is a perspective view showing another modification of the radial concave portion according to the present invention.

FIG. 12 is a perspective view showing a positional relationship according to shapes of a thrust recess and a radial recess according to the present invention.

FIG. 13 is a longitudinal sectional view showing a state in which a thrust recess and a radial recess of the present invention are applied to a bearing having a tapered end surface.

[Explanation of symbols]

1, 5, 6 ... porous bearing, 2 ... shaft hole, 3 ... chamfered part, 8
... axis, 10 ... end face, 11, 12, 14 ... thrust recess,
13A: Thrust recess A, 13B: Thrust recess B, 2
0: inner peripheral surface, 21, 22, 23, 24: radial concave portion.

Claims (6)

[Claims] Claims 1. From a shaft containing and supporting a fluid lubricant,
A substantially cylindrical porous bearing having an end surface receiving a thrust load and an inner peripheral surface receiving a radial load, wherein an opening edge of a shaft hole from the end surface to the inner peripheral surface is chamfered to form a chamfered portion. A plurality of radially extending thrust recesses extending from the outer peripheral side toward the inner peripheral side in the direction of rotation of the shaft are radially formed on the end face, and the peripheral edge of the inner peripheral face is located at a position corresponding to the thrust concave section. A porous bearing, wherein a radial concave portion that opens in a chamfered portion is formed. 2. A thrust recess A whose depth increases toward the inner peripheral side, and
Thrust recesses B whose depths increase toward the outer peripheral side are arranged substantially alternately in the circumferential direction on the end face, and the radial recesses correspond to the thrust recesses A and / or the thrust recesses B. The porous bearing according to claim 1, wherein the porous bearing is formed at a position where the porous bearing is located. 3. The porous bearing according to claim 1, wherein the number of the thrust recess and the number of the radial recess are a prime number of 3 or more. 4. The porous bearing according to claim 1, wherein an angle of the thrust recess with respect to a tangent of an outer periphery of the bearing is set in a range of 5 to 45 °. 5. The thrust recess has a depth of 5 to 100 μm.
m is set in the range of m.
5. The porous bearing according to any one of 4. 6. The porous bearing according to claim 1, wherein the end face is formed in a tapered shape that protrudes inward.