JP3236092U - Structure of dynamic pressure bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of a dynamic pressure bearing for solving a problem that an edge of a thrust plate easily collides with a bearing immediately before the start or stop of rotation in the structure of a conventional dynamic pressure bearing and the rotation becomes unstable. The purpose is to do.
A hydraulic bearing structure according to the present invention includes a sleeve, a bearing and a rotating member, the bearing is located inside the sleeve, and the rotating member is a thrust plate connected to a rotating shaft. The rotating shaft penetrates the bearing, and when the rotating member rotates, a dynamic pressure gap is formed between the thrust plate and the bearing, and the bearing is a shaft close to the thrust plate. It has a directional inner end surface, the axial inner end surface has an annular recessed region, and the outer peripheral edge of the thrust plate is axially aligned with the annular recessed region.
[Selection diagram] FIG. 4

Description

The present invention relates to a motor component, and particularly to a structure of a dynamic pressure bearing.

The structure of a conventional hydraulic bearing can have a sleeve and an oil-impregnated bearing assembled inside the sleeve, and the rotating member in the structure of the hydraulic bearing can have a thrust plate and a rotating shaft to rotate. The shaft can penetrate the oil-impregnated bearing, the thrust plate can be connected to the rotating shaft, and the outer peripheral edge of the thrust plate can be aligned within the radial range of the oil-impregnated bearing, so that it rotates. When the member rotates, a dynamic pressure gap can be formed between the thrust plate and the oil-impregnated bearing.

In the structure of the conventional dynamic pressure bearing, since the dynamic pressure gap is very narrow, if the rotating member has an unstable movement immediately before the start or stop of rotation, the outer peripheral edge of the thrust plate tends to swing, and the oil-impregnated bearing Since the collision with the bearing is repeated, the rotation of the rotating member becomes more unstable, and vibration and noise are generated.
In view of the above, it was necessary to improve the structure of the conventional dynamic pressure bearing.

China Publication No. 1619170

In order to solve the above problems, it is an object of the present invention to provide a structure of a dynamic pressure bearing that can reduce the collision of the thrust plate with the bearing.

It is an object of the present invention to further provide a structure of a dynamic pressure bearing that can improve assembly convenience.

Further, it is an object of the present invention to provide a structure of a dynamic pressure bearing capable of preventing leakage of lubricating oil.

It is an object of the present invention to further provide a structure of a dynamic pressure bearing that can improve manufacturing convenience.

In the present invention, terms related to directions such as "front", "rear", "left", "right", "top (top)", "bottom (bottom)", "inside", "outside", and "side". Refers to the direction of the drawings, and the above terms for each direction are used to explain or understand each embodiment of the present invention and are not intended to limit the present invention.

The classifiers such as "one" or "one" used in the parts or parts of the present invention are used for convenience and give the usual meaning to the claims of the present invention, and one in the present invention. Or, unless it should be interpreted as at least one and explicitly points to another meaning, one meaning may include multiple cases.

In the present invention, approximate terms such as "bond", "union", and "assembly" can be separated mainly after being connected without being destroyed, or cannot be separated after being connected. It can be selected according to the material of the part to be connected by a person skilled in the art or the demand for assembly.

The structure of the dynamic pressure bearing according to the present invention includes a sleeve, a bearing and a rotating member, the bearing is located inside the sleeve, and the rotating member has a thrust plate connected to a rotating shaft. The rotating shaft penetrates the bearing, and when the rotating member rotates, a dynamic pressure gap is formed between the thrust plate and the bearing, and the bearing has an axial inner end surface close to the thrust plate. The inner end surface in the axial direction has an annular recessed region, and the outer peripheral edge of the thrust plate is axially aligned with the annular recessed region.

As a result, in the structure of the dynamic pressure bearing according to the present invention, the outer peripheral edge of the thrust plate is aligned with the annular recessed region in the axial direction, so that even if the rotating member rotates and swings, the outer peripheral edge of the thrust plate is formed. Since it is possible to enter the annular recess region, it is possible to prevent the thrust plate from colliding with the bearing, reduce noise and vibration due to the collision, and avoid wear, thereby improving the smoothness of rotation of the rotating member. Can have the effect of causing.

Further, the sleeve has a shoulder portion, the axial inner end surface of the bearing abuts on the shoulder portion, and the axial inner end surface and the inner bottom surface of the sleeve of the sleeve face each other with an axial distance. However, the annular recessed area may not be completely covered by the shoulder. This has the effect of ensuring that the outer peripheral edge of the thrust plate enters the annular recessed region and improving the smoothness of rotation of the rotating member.

Further, the annular recessed region may be an annular groove on the inner end surface in the axial direction. As a result, the structure is simple and easy to manufacture, which has the effect of reducing the manufacturing cost.

Further, the outer peripheral edge of the thrust plate can be aligned with the central portion of the annular groove in the axial direction. This has the effect of ensuring that the outer peripheral edge of the thrust plate enters the annular recessed region and improving the smoothness of rotation of the rotating member.

Further, the depth of the annular groove can be gradually decreased from the center toward both sides. As a result, the annular recessed region can be formed in a triangular or arc shape, which has the effect of improving the convenience of manufacturing.

Further, the depth of the annular groove may be the same from the center to both sides. As a result, the annular recessed region can be formed in a U-shape, which has the effect of improving the convenience of manufacturing.

Further, the bearing has an axial outer end surface facing the axial inner end surface in the axial direction, the axial outer end surface has another annular recess region, and the two annular recess regions are symmetrical. Can be installed in. As a result, even if either the axial inner end surface or the axial outer end surface is close to the thrust plate, the outer peripheral edge of the thrust plate is aligned with the annular recessed region in the axial direction, which makes assembly difficult depending on the orientation. It can be avoided and has the effect of improving assembly convenience.

Further, the bearing has a radial annular surface and an axial annular surface connected to each other at a position close to the outer peripheral surface, and the annular recess is surrounded between the radial annular surface and the axial annular surface. A region can be formed and the radial annular surface can be orthogonal to the axial annular surface. As a result, the structure is simple and easy to manufacture, which has the effect of reducing the manufacturing cost.

Further, the bearing has a radial annular surface and an axial annular surface connected to each other at a position close to the outer peripheral surface, and the annular recess so as to surround the bearing between the radial annular surface and the axial annular surface. A region can be formed and an obtuse angle can be formed between the radial annular surface and the axial annular surface. As a result, the structure is simple and easy to manufacture, and the outer peripheral edge of the thrust plate is more likely to enter the annular recessed region, which has the effect of reducing the manufacturing cost.

Further, the bearing has an axial outer end surface facing the axial inner end surface in the axial direction, a leakage prevention ring is coupled to the sleeve, covers the axial outer end surface of the bearing, and the rotating shaft The bearing penetrates the through hole of the leakage prevention ring and the shaft hole of the rotating shaft, and the bearing has a first guide slope connected to the edge of the shaft hole and the outer end surface in the axial direction, and has a diameter of the through port. The width may be smaller than the radial width of the connecting portion between the first guide slope and the axial outer end surface. As a result, the leakage prevention ring can dam the lubricating oil flowing out along the first guide slope, and has the effect of preventing the leakage of the lubricating oil.

Further, the leakage prevention ring has a slope, the slope is adjacent to the through port and faces the bearing, and an oil cutoff space is formed between the slope and the axial outer end surface of the bearing. be able to. As a result, when the lubricating oil flows out to the upper end of the bearing along the first guide slope, it can subsequently flow into the oil cutoff space, so that it becomes difficult for the lubricating oil to flow out from the through hole of the leakage prevention ring, and the lubricating oil becomes difficult to flow out. It has the effect of preventing leakage.

Further, the rotating shaft has an inner end surface located inside the sleeve, a protrusion is projected on the inner end surface, the thrust plate is connected to the protrusion, and the height of the protrusion is the height of the thrust plate. Larger than the thickness, an oil-impregnated space can be formed between the thrust plate and the inner end surface. As a result, the lubricating oil located in the oil-impregnated space can be smoothly replenished to the dynamic pressure gap between the thrust plate and the axial inner end surface of the bearing, which has the effect of improving the smoothness of rotation of the rotating member.

Further, the bearing has a second guide slope connected to the shaft hole and the inner end surface in the axial direction, and the inner end surface of the rotating shaft can be aligned with the second guide slope in the radial direction. .. This has the effect of relatively reducing the collision of the peripheral edge of the inner end surface of the rotating shaft with the inner wall of the bearing immediately before the start or stop of rotation.

Further, the sleeve has an annular recess located on the inner bottom surface of the sleeve of the sleeve, and the outer peripheral edge of the thrust plate can be aligned with the annular recess in the axial direction. As a result, even if the rotating member rotates and swings, the outer peripheral edge of the thrust plate can enter the annular recess region and can also enter the annular recess, so that the thrust plate can be prevented from colliding with the sleeve. It has the effect of improving the smoothness of rotation of the rotating member.

Further, a plurality of dynamic pressure grooves are included, and the plurality of dynamic pressure grooves can be recessed only on the upper surface, the lower surface, or the upper surface of the thrust plate. This has the effect of further improving the dynamic pressure effect generated when the structure of the dynamic pressure bearing operates.

Further, the plurality of dynamic pressure grooves do not have to communicate with the outer peripheral edge of the thrust plate. As a result, most of the oil film can be stored in the dynamic pressure groove to generate a stronger dynamic pressure, which has the effect of improving the dynamic pressure effect generated when the structure of the dynamic pressure bearing operates.

An exploded perspective view of the first embodiment according to the present invention. FIG. 3 is a plan view showing that the dynamic pressure groove does not communicate with the outer peripheral edge of the thrust plate in the first embodiment according to the present invention. FIG. 3 is a plan view showing that the dynamic pressure groove communicates with the outer peripheral edge of the thrust plate in the first embodiment according to the present invention. The assembled sectional view of the 1st Example which concerns on this invention. Enlarged view of A in FIG. FIG. 3 is a cross-sectional view showing that the annular recessed region is formed in an arc shape in the first embodiment according to the present invention. FIG. 3 is a cross-sectional view showing that the annular recessed region is formed in a U shape in the first embodiment according to the present invention. A cross-sectional view of a part of the assembled second embodiment according to the present invention. The assembled sectional view of the 3rd Example which concerns on this invention. An enlarged view of B in FIG. FIG. 3 is a cross-sectional view showing that an obtuse angle is formed between the radial annular surface and the axial annular surface in the third embodiment according to the present invention.

Examples of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the first embodiment of the structure of the dynamic pressure bearing according to the present invention includes a sleeve 1, a bearing 2 and a rotating member 3, and the bearing 2 is located inside the sleeve 1 and rotates. The member 3 is rotatably coupled to the bearing 2.

The sleeve 1 is generally hollow in the shape of a cup and is used for accommodating the bearing 2 and injecting lubricating oil. In this embodiment, the sleeve 1 can have an facing opening 11 and a sleeve inner bottom surface 12, and the bearing 2 can be accommodated inside the sleeve 1 from the opening 11. The inner bottom surface 12 of the sleeve may be closed, thereby effectively preventing the lubricating oil from leaking from the sleeve 1. The inside of the sleeve 1 may further have a shoulder portion 13, whereby the bearing 2 housed through the opening 11 can abut on the shoulder portion 13.

The sleeve 1 can further have a recess 14. The recess 14 may be recessed in the inner bottom surface 12 of the sleeve, whereby the recess 14 can be axially opposed to the rotating member 3, and the recess 14 is a space for collecting lubricating oil or one of the rotating members 3. The part can be a space for insertion.

The bearing 2 is located inside the sleeve 1, and the bearing 2 can have an axial inner end surface 21 and an axial outer end surface 22 facing each other in the axial direction, and the axial inner end surface 21 is inside the sleeve of the sleeve 1. Close to the bottom 12. The bearing 2 can have a shaft hole 23, the shaft hole 23 can penetrate the axial outer end surface 22 and the axial inner end surface 21, and the bearing 2 is located on the shoulder portion 13 of the sleeve 1 from the axial inner end surface 21. By abutting, the axial inner end surface 21 can be opposed to the sleeve inner bottom surface 12 of the sleeve 1 at an axial interval. The bearing 2 can be brought into close contact with the inner peripheral surface of the sleeve 1, and preferably by applying laser welding to the outer end of the coupling portion, the coupling stability between the bearing 2 and the sleeve 1 is improved.

The bearing 2 has an annular recessed region 24, the annular recessed region 24 is located on the inner end surface 21 in the axial direction, and the annular recessed region 24 is partially aligned with the shoulder portion 13, so that the annular recessed region 24 becomes a shoulder. It is possible to avoid being completely shielded by the portion 13. More specifically, the annular recessed region 24 is, in principle, an annular groove 24a formed on the inner end surface 21 in the axial direction, and the shape of the annular recessed region 24 is not limited in the present invention. For example, the depth of the groove in the annular recessed region 24 may gradually decrease from the center toward both sides, and may be triangular or arcuate, as shown in FIGS. 5 and 6. Alternatively, as shown in FIG. 7, the depth of the groove of the annular recessed region 24 may be the same from the center to both sides, and the connecting portion between the bottom of the annular recessed region 24 and both sides may form a guide angle. As a result, the annular recessed region 24 can be formed in a substantially U-shape. In other embodiments, the annular recessed region 24 may be in other embodiments and is not limited to the drawings of this embodiment.

As shown in FIGS. 1 and 4, the bearing 2 can have a first guide slope 25 and a second guide slope 26, and the first guide slope 25 is connected to the shaft hole 23 and the axial outer end surface 22. The connecting portion between the guide slope 25 and the axial outer end surface 22 can form a diameter width D1. The second guide slope 26 can be spaced apart from the first guide slope 25 in the axial direction, and the second guide slope 26 can be connected to the shaft hole 23 and the inner end surface 21 in the axial direction.

The rotating member 3 has a rotating shaft 31 and a thrust plate 32, the rotating shaft 31 penetrates the shaft hole 23 of the bearing 2, and the rotating shaft 31 has an inner end surface 311 and an outer end surface 312 facing each other, and the inner end surface 311. Is located inside the sleeve 1 and the outer end surface 312 is located outside the sleeve 1. The inner end surface 311 of the rotating shaft 31 can be aligned with the second guide slope 26 of the bearing 2 in the radial direction, and immediately before the rotation of the rotating shaft 3 starts or stops, the peripheral edge of the inner end surface 311 of the rotating shaft 31 is formed. Collision with the inner wall of the bearing 2 can be relatively reduced. The thrust plate 32 is connected to the rotating shaft 31, a dynamic pressure gap G is formed between the thrust plate 32 and the bearing 2, and the outer peripheral edge E of the thrust plate 32 is aligned with the annular recessed region 24 in the axial direction. Preferably, the outer peripheral edge E of the thrust plate 32 is axially aligned with the central portion of the annular groove 24a, thereby ensuring that the outer peripheral edge E of the thrust plate 32 enters the annular recessed region 24. The method of connecting the thrust plate 32 and the rotating shaft 31 is not limited in the present invention. For example, it may be tight, and it is preferable to add laser welding to the jointed portion. In another embodiment, the thrust plate 32 and the rotating shaft 31 may be connected by integral molding.

In addition, the axial outer end surface 22 can have yet another annular recessed region 24, with the annular recessed region 24 located at the axial inner end surface 21 and the annular recessed region 24 located at the axial outer end surface 22. Are preferably installed symmetrically, whereby the outer peripheral edge E of the thrust plate 32 is axially located even if either the axial inner end surface 21 or the axial outer end surface 22 is close to the thrust plate 32. Since it is aligned with the annular recessed region 24, it is possible to avoid the problem that assembly becomes difficult depending on the orientation.

Further, the rotary shaft 31 can have a protrusion 313, the protrusion 313 projects from the inner end surface 311 of the rotary shaft 31, and the thrust plate 32 is connected to the protrusion 313. Further, the height H of the protrusion 313 may be larger than the thickness T of the thrust plate 32, and the thrust plate 32 and the inner end surface 311 of the rotating shaft 31 are spaced apart from each other so as to be spaced from the thrust plate 32. An oil-impregnated space Q is formed between the rotating shaft 31 and the inner end surface 311, and the lubricating oil located in the oil-impregnated space Q flows from the dynamic pressure gap G between the thrust plate 32 and the axial inner end surface 21 of the bearing 2. Replenish smoothly.

Further, the rotary shaft 31 can have a leak prevention annular groove 314, and the leak prevention annular groove 314 is provided around the peripheral surface 315 of the rotary shaft 31, so that the lubricating oil can be applied along the peripheral surface 315 of the rotary shaft 31. It is possible to allow the lubricating oil to flow back into the sleeve 1 according to gravity after flowing into the leakage prevention annular groove 314, and the lubricating oil leaks along the peripheral surface 315 of the rotating shaft 31. It can be effectively reduced.

The structure of the dynamic pressure bearing of the present invention can further include a leak prevention ring 4, the leak prevention ring 4 is coupled to the sleeve 1 and covers the axial outer end surface 22 of the bearing 2, and the leak prevention ring 4 is made of lubricating oil. It can be used to prevent spillage. More specifically, the rotating shaft 31 can penetrate the through port 41 of the leakage prevention ring 4, and the diameter width D2 of the through port 41 is the diameter width D1 of the connecting portion between the first guide slope 25 and the axial outer end surface 22. It is preferably smaller, whereby the leakage prevention ring 4 can dam the lubricating oil flowing out along the first guide slope 25, and has an effect of preventing the leakage of the lubricating oil.

Further, the leak prevention ring 4 can have a slope 42, and the slope 42 is adjacent to the through hole 41 and faces the bearing 2, so that the thickness of the leak prevention ring 4 gradually decreases toward the through port 41. As a result, an oil cutoff space S can be formed between the slope 42 and the axial outer end surface 22 of the bearing 2. As a result, when the lubricating oil flows out to the upper end of the bearing 2 along the first guide slope 25, it can subsequently flow into the oil cutoff space S, so that it is difficult for the lubricating oil to flow out from the through port 41 of the leakage prevention ring 4. Become.

It should be noted that the structure of the dynamic pressure bearing of the present invention may further include a plurality of dynamic pressure grooves 5 in order to further improve the dynamic pressure effect generated when the structure of the dynamic pressure bearing of the present invention operates. The plurality of dynamic pressure grooves 5 can be located on the inner bottom surface 12 of the sleeve of the sleeve 1, the axial inner end surface 21 of the bearing 2, the upper surface 32a and the lower surface 32b of the thrust plate 32, or in the sleeve of the sleeve 1. It is also possible to prevent the bottom surface 12 and the bearing 2 from having the dynamic pressure groove 5 on the inner end surface 21 in the axial direction, and to have a plurality of dynamic pressure grooves 5 only on the upper surface 32a and the lower surface 32b of the thrust plate 32. Alternatively, a plurality of dynamic pressure grooves 5 may be provided only on the upper surface 32a of the thrust plate 32, and the above can be selected and changed by those skilled in the art according to demand, and is not limited to the drawings of the present invention. In this embodiment, it is described that a plurality of dynamic pressure grooves 5 are recessed in both the upper surface 32a and the lower surface 32b of the thrust plate 32, and the dynamic pressure grooves 5 and the lower surface 32b located on the upper surface 32a are located. The dynamic pressure groove 5 can be aligned or displaced in the axial direction, and is not limited in the present invention.

Further, the form of the dynamic pressure groove 5 is not limited in the present invention. For example, it may be a radial arc groove, or a "human" groove shown in the drawings, which can be adjusted according to demand. Further, each dynamic pressure groove 5 can have a curved portion 51, and the curved portion 51 is located between the internal curve stage 52 and the external curve stage 53 of the dynamic pressure groove 5, and the external curve stage 53 is inside. It is closer to the outer peripheral edge E than the curve step 52. As shown in FIG. 2, the outer curve step 53 preferably does not communicate with the outer peripheral edge E of the thrust plate 32, whereby most of the oil film can be stored in the dynamic pressure groove 5, and the dynamic pressure can be further increased. It can be increased to provide a better dynamic pressure effect. In another embodiment, the outer curve step 53 may communicate with the outer peripheral edge E of the thrust plate 32, as shown in FIG. 3, and is not limited in the present invention.

As shown in FIG. 4, in the rotation of the rotating member 3, the lubricating oil in the dynamic pressure gap G located between the thrust plate 32 and the bearing 2 can form an oil film, whereby the rotating member can be formed. The rotation of 3 can be kept smooth, and further, by aligning the outer peripheral edge E of the thrust plate 32 with the annular recessed region 24 in the axial direction, even if the rotating member 3 rotates and swings, the thrust plate 32 Since the outer peripheral edge E of the wheel can enter the annular recessed region 24, it is possible to prevent the thrust plate 32 from colliding with the bearing 2. Therefore, in the structure of the dynamic pressure bearing of the present embodiment, vibration and noise generated when colliding with the bearing 2 are unlikely to occur, and wear can be avoided, so that the smoothness of rotation of the rotating member can be improved. Can be done.

As shown in FIG. 8, in the second embodiment of the structure of the dynamic pressure bearing according to the present invention, the sleeve 1 can have an annular recess 15, and the annular recess 15 can be located on the inner bottom surface 12 of the sleeve. Moreover, the outer peripheral edge E of the thrust plate 32 can be aligned with the annular recess 15 in the axial direction. The shape of the annular recess 15 may be, for example, triangular, arc-shaped or U-shaped, and is not limited in the present invention. As a result, even if the rotating member 3 rotates and swings, the outer peripheral edge E of the thrust plate 32 can enter the annular recess region 24 and can also enter the annular recess 15, so that the thrust plate 32 enters the sleeve 1. It is possible to prevent collision. Therefore, in the structure of the dynamic pressure bearing of this embodiment, it is possible to further avoid vibration and noise generated when colliding with the sleeve 1 and improve the smoothness of rotation of the rotating member 3.

As shown in FIG. 9, in the third embodiment of the structure of the dynamic pressure bearing according to the present invention, the annular recessed region 24 is close to the outer peripheral surface 27 of the bearing 2. More specifically, the bearing 2 can have a radial annular surface 28 and an axial annular surface 29 that are connected to each other near the outer peripheral surface 27, and the radial annular surface 28 has the outer peripheral surface 27 and the axial annular surface 29. An annular recessed region 24 can be formed so as to surround between the radial annular surface 28 and the axial annular surface 29, and the radial annular surface 28 and the axial direction can be formed. In principle, the outer peripheral edge E of the thrust plate 32 can be aligned in the axial direction in the annular recessed region 24 formed by surrounding the annular surface 29. For example, the radial annular surface 28 can be orthogonal to the axial annular surface 29 as shown in FIG. 10, or the radial annular surface 28 is with the axial annular surface 29 as shown in FIG. It is also possible to form an obtuse angle θ between the two. The outer peripheral edge E of the thrust plate 32 can more easily enter the annular recessed region 24, whereby the annular recessed region 24 having different shapes and dimensions can be formed.

As described above, in the structure of the dynamic pressure bearing according to the present invention, the outer peripheral edge of the thrust plate is aligned with the annular recessed region in the axial direction, so that even if the rotating member rotates and swings, the outer peripheral edge of the thrust plate is formed. Since it is possible to enter the annular recess region, it is possible to prevent the thrust plate from colliding with the bearing, reduce noise and vibration due to the collision, and avoid wear, thereby improving the smoothness of rotation of the rotating member. Can have the effect of causing.

The invention can be implemented in other ways without departing from its spirit and essential features. Therefore, the embodiments described herein are exemplary and do not limit the scope of the present invention.

1 Sleeve 11 Opening 12 Sleeve inner bottom surface 13 Shoulder 14 Recess 15 Annular recess 2 Bearing 21 Axial inner end surface 22 Axial outer end surface 23 Shaft hole 24 Circular recess area 24a Circular groove 25 1st guide slope 26 2nd guide slope 27 Outer circumference Surface 28 Radial annular surface 29 Axial annular surface 3 Rotating member 31 Rotating shaft 311 Inner end surface 312 Outer end surface 313 Projection 314 Leakage prevention annular groove 315 Peripheral surface 32 Thrust plate 32a Upper surface 32b Lower surface 4 Leakage prevention ring 41 Through port 42 Slope 5 Dynamic pressure groove 51 Curved part 52 Internal curve stage 53 External curve stage D1 Diameter width D2 Diameter width E Outer peripheral edge G Dynamic pressure gap H Height T Thickness S Oil-free space Q Oil-impregnated space θ Oblique angle

Claims (16)

Includes sleeves, bearings and rotating members
The bearing is located inside the sleeve and
The rotating member has a thrust plate connected to a rotating shaft, and the rotating shaft penetrates the bearing, and when the rotating member rotates, a dynamic pressure is applied between the thrust plate and the bearing. A gap is formed,
The bearing has an axial inner end surface close to the thrust plate, the axial inner end surface has an annular recess region, and the outer peripheral edge of the thrust plate is axially aligned with the annular recess region. The characteristic structure of the dynamic bearing. A shoulder portion is provided inside the sleeve, the axial inner end surface of the bearing abuts on the shoulder portion, and the axial inner end surface and the inner bottom surface of the sleeve of the sleeve face each other at a distance in the axial direction. The structure of a dynamic pressure bearing according to claim 1, wherein the annular recessed region is not completely shielded by the shoulder portion. The structure of a dynamic pressure bearing according to claim 1, wherein the annular recess region is an annular groove on the inner end surface in the axial direction. The structure of a dynamic pressure bearing according to claim 3, wherein the outer peripheral edge of the thrust plate is aligned with the central portion of the annular groove in the axial direction. The structure of a dynamic pressure bearing according to claim 4, wherein the depth of the annular groove gradually decreases from the center toward both sides. The structure of a dynamic pressure bearing according to claim 4, wherein the depth of the annular groove is the same from the center to both sides. The bearing has an axial outer end surface facing the axial inner end surface in the axial direction, the axial outer end surface has another annular recess region, and the two annular recess regions are installed so as to be symmetrical. The structure of the hydraulic bearing according to claim 1, wherein the structure is characterized by the above. The bearing has a radial annular surface and an axial annular surface that are connected to each other at a position close to the outer peripheral surface, and the annular recess region is surrounded between the radial annular surface and the axial annular surface. The structure of a hydraulic bearing according to claim 1, wherein the radial annular surface is formed and is orthogonal to the axial annular surface. The bearing has a radial annular surface and an axial annular surface that are connected to each other at a position close to the outer peripheral surface, and the annular recess region is surrounded between the radial annular surface and the axial annular surface. The structure of a hydraulic bearing according to claim 1, wherein the structure is formed to form an obtuse angle between the radial annular surface and the axial annular surface. The bearing has an axial outer end surface facing the axial inner end surface in the axial direction, a leakage prevention ring is coupled to the sleeve to cover the axial outer end surface of the bearing, and the rotating shaft has the leakage. The bearing penetrates the through hole of the prevention ring and the shaft hole of the rotating shaft, and the bearing has a first guide slope connected to the edge of the shaft hole and the outer end surface in the axial direction, and the diameter width of the through port is The structure of a hydraulic bearing according to claim 1, wherein the structure is smaller than the diameter width of the connecting portion between the first guide slope and the outer end surface in the axial direction. The leak prevention ring has a slope, the slope is adjacent to the through hole and faces the bearing, and an oil cutoff space is formed between the slope and the axial outer end surface of the bearing. The structure of the dynamic pressure bearing according to claim 10. The rotating shaft has an inner end surface located inside the sleeve, a protrusion is projected on the inner end surface, the thrust plate is connected to the protrusion, and the height of the protrusion is higher than the thickness of the thrust plate. The structure of a dynamic pressure bearing according to claim 1, wherein an oil-impregnated space is formed between the thrust plate and the inner end surface. The bearing has a second guide slope connected to the shaft hole and the axial inner end surface, and the inner end surface of the rotating shaft is radially aligned with the second guide slope. The structure of the dynamic pressure bearing according to claim 12. The dynamic pressure according to claim 1, wherein the sleeve has an annular recess located on the inner bottom surface of the sleeve of the sleeve, and the outer peripheral edge of the thrust plate is axially aligned with the annular recess. Bearing structure. The invention according to any one of claims 1 to 14, further comprising a plurality of dynamic pressure grooves, wherein the plurality of dynamic pressure grooves are recessed only on the upper surface, the lower surface, or the upper surface of the thrust plate. Structure of dynamic pressure bearing. The structure of a dynamic pressure bearing according to claim 15, wherein the plurality of dynamic pressure grooves do not communicate with the outer peripheral edge of the thrust plate.

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