Sliding member

Abstract

The present invention provides a sliding member having a high floating effect. The sliding member (3) is disposed between a housing (2) and a shaft (1) inserted through the housing (2) and has a pair of sliding surfaces (11, 21) that rotate relative to each other, and at least one of the sliding surfaces (11) is provided with a dynamic pressure generating groove (13). The dynamic pressure generating groove (13) has an introduction part (14) on one side that communicates with the one space (S1), an introduction part (15) on the other side that communicates with the other space (S2), and a tip part (17B) at which the two introduction parts (14, 15) converge on the downstream side of relative rotation. The tip part (17B) side of the dynamic pressure generating groove (13) is shallower than the introduction part (14) on one side and the introduction part (15) on the other side of the dynamic pressure generating groove (13).

Description

Technical Field

[0001] This invention relates to a sliding component that rotates relative to the shaft, for example to a sliding component used in a shaft sealing device for sealing the rotating shaft of rotating machinery in the fields of automobiles, general industrial machinery or other sealing, or a sliding component used in the bearings of machinery in the fields of automobiles, general industrial machinery or other bearings. Background Technology

[0002] The bearing assembly supporting the rotating shaft includes a thrust bearing that rotatably supports the rotating shaft in the thrust direction. In recent years, due to environmental countermeasures and other reasons, it has been desirable to reduce the energy lost due to slippage in such thrust bearings.

[0003] For example, the thrust bearing shown in Patent Document 1 includes an annular sliding ring fixed to the rotating shaft and an annular sliding ring disposed on the housing side. On the sliding surface of the sliding ring on the housing side, a plurality of so-called herringbone-shaped dynamic pressure grooves, approximately V-shaped when viewed axially, are formed circumferentially. The depth of the dynamic pressure grooves is constant, the top of the dynamic pressure grooves faces the downstream side of the relative rotation, the outer diameter end of the dynamic pressure groove communicates with the outer diameter side space, and the inner diameter end communicates with the inner diameter side space. These outer diameter side spaces and the inner diameter side spaces, i.e., the housing, are filled with lubricating oil.

[0004] When the rotating shaft rotates, lubricating oil is supplied from the outer and inner diameter ends of the hydrodynamic groove, generating hydrodynamic pressure at the top of the groove. This hydrodynamic pressure causes the sliding ring on the rotating shaft side to float slightly relative to the sliding ring on the housing side in the direction of separation of the sliding surfaces, allowing lubricating oil to flow in and thus improving lubrication. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-327545 (page 7) Figure 2 ) Summary of the Invention The problem that the invention aims to solve

[0006] In a thrust bearing like that in Patent Document 1, by increasing the circumferential length of the hydrodynamic groove, more lubricating oil can be introduced from the outer diameter side space and the inner diameter side space, thus generating a larger positive pressure. However, since the positive pressure is generated at the top of the hydrodynamic groove, the positive pressure on the sliding surface is dispersed circumferentially, which may prevent a sufficient levitation effect from being achieved.

[0007] This invention was made in view of such a problem, and its purpose is to provide a sliding component with a high levitation effect. Methods for solving problems

[0008] To address the aforementioned issues, the sliding component of the present invention is disposed between a housing and a shaft inserted into the housing, with a pair of sliding surfaces rotating relative to each other. At least one sliding surface has a dynamic pressure generating groove, the dynamic pressure generating groove having an inlet portion communicating with one space on one side, an inlet portion communicating with another space on the other side, and a front end portion where the two inlet portions merge on the downstream side during relative rotation. Compared to the inlet side on one side and the inlet side on the other side of the dynamic pressure generating groove, the front end side of the dynamic pressure generating groove is shallower. As a result, the pressure of the fluid introduced from the inlet on one side and the other side increases as it moves toward the front end, thus enabling the positive pressure to be increased over a large circumferential range.

[0009] The dynamic pressure generating groove can gradually become shallower from at least one of the inlet portions toward the front end portion. This allows for a gradual increase in pressure.

[0010] The bottom surface of the front end can be connected to the platform in a curved shape along the circumference. Therefore, it is easy to guide the fluid flowing in the circumferential direction in the circumferential direction.

[0011] The bottom surface of the front end can be connected to the platform in a radially curved shape. Therefore, it is also easy to guide fluids flowing circumferentially in the radial direction.

[0012] The inclination angle of the bottom surface of at least one of the inlet portions may be greater than the inclination angle of the bottom surface of the front end portion. Therefore, it is easy to guide the fluid in the inlet to the front end, and a larger front end can be ensured to generate positive pressure in the circumferential direction.

[0013] At least one of the inlet portions may be configured radially, and the front end portion may be configured circumferentially. Therefore, a larger front end can be ensured to generate positive pressure in the circumferential direction.

[0014] The front end can taper at the front end along the positive rotation direction. This allows for the generation of significant positive pressure at the front end of the front section.

[0015] Alternatively, the inlet portion on one side may be wider and longer than the inlet portion on the other side. Therefore, since the volume of the inlet on one side is larger than that of the inlet on the other side, more fluid can be introduced into a space.

[0016] The inlet portion on one side of the front end is deeper than the inlet portion on the other side of the front end. Therefore, more fluid can be introduced from one side of the inlet, making it easier to generate positive pressure on the other side of the front end. Attached Figure Description

[0017] Figure 1 This is a longitudinal sectional view showing an example of the thrust bearing in Embodiment 1 of the present invention. Figure 2 This is a diagram showing the sliding surface of the stationary ring in Example 1 as viewed from the axial direction. Figure 3 This is an enlarged view of the sliding surface of the stationary ring in Example 1, viewed from the axial direction. Figure 4 This is a schematic cross-sectional view obtained by cutting along the front end of the front end of the inlet groove from the inner diameter side in Example 1. Figure 5 (a) is Figure 4 AA section view, (b) is Figure 4 BB cross-sectional view. Figure 6 This is an explanatory diagram showing the movement of fluid in the groove caused by the dynamic pressure generated when the sliding surface of the stationary ring in Example 1 is rotated axially. Figure 7 This is an explanatory diagram showing the pressure distribution in the dynamic pressure generating groove of Example 1. Figure 8 (a) is a schematic cross-sectional view obtained by cutting along the front end of the front end of the inlet groove from the inner diameter side in Embodiment 2 of the present invention, (b) is a CC cross-sectional view of (a), and (c) is a DD cross-sectional view of (a). Figure 9 This is an enlarged view of the sliding surface of the stationary ring in Embodiment 3 of the present invention, viewed from the axial direction. Figure 10 This is a schematic cross-sectional view obtained by cutting along the front end of the confluence portion from the inclined groove on the inner diameter side in Embodiment 4 of the present invention. Figure 11 This is an enlarged view of the sliding surface of the stationary ring in Embodiment 5 of the present invention, viewed from the axial direction. Figure 12 This is an enlarged view of the inner circumferential surface of the radial bearing in Embodiment 6 of the present invention, viewed from the axial direction. Detailed Implementation

[0018] The following describes the method of implementing the sliding component of the present invention based on embodiments. Example 1

[0019] Regarding the sliding component of Embodiment 1, refer to... Figures 1 to 7 The following explanation will be provided. Furthermore, in this embodiment, the example given is a thrust bearing with a sliding component. Additionally, the method in which the same lubricating oil exists in both the inner and outer spaces of the thrust bearing will be explained.

[0020] like Figure 1As shown, the bearing device in this embodiment mainly consists of a rotating shaft 1, a housing 2, a thrust bearing 3, and a radial bearing 4.

[0021] The housing 2 is cylindrical and is through which the rotating shaft 1 is inserted. A radial bearing 4 is axially separated between the rotating shaft 1 and the housing 2. The radial bearing 4 allows the rotating shaft 1 to rotate while limiting its tilt.

[0022] A thrust bearing 3 is disposed on the axial side of the rotating shaft 1, relative to the radial bearing 4. The thrust bearing 3 is mainly composed of a circular stationary ring 10 and a circular rotating ring 20, which serve as sliding components.

[0023] The rotating ring 20 is mounted on the rotating shaft 1 in a state that allows it to rotate together with the rotating shaft 1. The stationary ring 10 is fixed to the housing 2 in a non-rotating state. The sliding surfaces 11 of these stationary rings 10 slide in close contact with the sliding surfaces 21 of the rotating rings 20. Furthermore, the sliding surfaces 21 of the rotating rings 20 are flat surfaces without grooves or other recesses.

[0024] The stationary ring 10 and the rotating ring 20 are typically formed from a combination of SiC (hard material) and SiC (hard material) or a combination of SiC (hard material) and carbon (soft material), but are not limited to these. Any sliding material used as a sliding material for bearings can be applied. Furthermore, SiC can be represented by sintered bodies containing boron, aluminum, carbon, etc., as sintering aids, and can be composed of two or more phases with different compositions. Examples include SiC with dispersed graphite particles, reaction-sintered SiC composed of SiC and Si, SiC-TiC, SiC-TiN, etc. As for carbon, resin-molded carbon and sintered carbon, represented by carbonaceous and graphitic carbon, can be used. In addition to the above-mentioned sliding materials, metallic materials, resin materials, surface-modified materials (coating materials), and composite materials can also be used.

[0025] like Figure 2 and Figure 3 As shown, the rotating ring 20, which is the sliding component on the opposite side, slides counterclockwise relative to the stationary ring 10 as indicated by the solid arrow. The direction of rotation indicated by the solid arrow will be explained below as the positive direction of rotation.

[0026] A plurality of dynamic pressure generating grooves 13 (10 in this embodiment) are evenly distributed circumferentially on the sliding surface 11 of the stationary ring 10. In addition, the portion of the sliding surface 11 other than the dynamic pressure generating grooves 13 is a flat platform 12.

[0027] The dynamic pressure generating groove 13 is composed of an outer diameter side inlet groove 14 as an inlet portion on one side, an inner diameter side inlet groove 15 as an inlet portion on the other side, and a front end side groove 17. It is a so-called herringbone-shaped groove that is roughly V-shaped when viewed from the axial direction.

[0028] like Figure 3 As shown, the outer diameter side inlet groove 14 is connected to the outer space S1, which is a space, and when viewed axially, it tilts in the positive rotation direction and extends in the inner diameter direction.

[0029] When viewed axially, the outer diameter side inlet groove 14 is roughly arc-shaped, protruding towards the inner diameter side. The inner diameter end 14a of the outer diameter side inlet groove 14 faces the roughly positive rotation direction and is wider than the outer diameter end 14b.

[0030] Furthermore, the curvature of the sidewall 14c on the downstream side of the outer diameter inlet groove 14 is greater than the curvature of the sidewall 14d on the upstream side of the outer diameter inlet groove 14. Also, the curvature referred to here is the average curvature. The same applies below.

[0031] The radial length L10 of sidewall 14c is shorter than the radial length L11 of sidewall 14d. In this embodiment, sidewall 14c has an inflection point, while sidewall 14d does not, and its curvature is approximately constant. Furthermore, the curvature of sidewalls 14c and 14d can be constant or variable.

[0032] The inner diameter side inlet groove 15 is connected to the inner space S2, which is another space, and when viewed axially, it tilts in the positive rotation direction and extends in the outer diameter direction.

[0033] When viewed axially, the inner diameter side inlet groove 15 is roughly arc-shaped, protruding towards the outer diameter side. The outer diameter end 15a of the inner diameter side inlet groove 15 faces the roughly positive rotation direction and is wider than the inner diameter end 15b.

[0034] Specifically, the curvature of the sidewall 15c on the downstream side of the inner diameter side inlet groove 15 is greater than the curvature of the sidewall 15d on the upstream side of the inner diameter side inlet groove 15.

[0035] The radial length L20 of sidewall 15c is shorter than the radial length L21 of sidewall 15d. In this embodiment, sidewall 15c has an inflection point, while sidewall 15d does not, and its curvature is approximately constant. Furthermore, sidewalls 14d and 15d are connected in an approximately V-shape when viewed axially. Additionally, the curvature of sidewalls 15c and 15d can be constant or variable.

[0036] The front end groove 17 includes: a confluence portion 17A where the inner diameter end 14a of the outer diameter side guide groove 14 and the outer diameter end 15a of the inner diameter side guide groove 15 merge; and a front end portion 17B extending from the confluence portion 17A in the forward rotation direction. Furthermore, as described later, in this embodiment, the front end portion 17B is a positive pressure generating region, and the confluence portion 17A is a non-positive pressure generating region located further upstream of the relative rotation than the front end portion 17B.

[0037] When viewed axially, the front end side groove 17 tapers from the confluence portion 17A toward the front end portion 17B in the positive rotational direction. The front end portion 17Ba of the front end portion 17B is located near the radial center of the sliding surface 11.

[0038] Compared to the outer diameter side guide groove 14 and the inner diameter side guide groove 15, the circumferential component of the front-end side groove 17 is greater than its radial component, while the radial component of the outer diameter side guide groove 14 and the inner diameter side guide groove 15 is greater than its circumferential component compared to the front-end side groove 17. In other words, the outer diameter side guide groove 14 and the inner diameter side guide groove 15 are arranged radially compared to the front-end side groove 17, and the front-end side groove 17 is arranged circumferentially compared to the outer diameter side guide groove 14 and the inner diameter side guide groove 15. Therefore, the circumferential dimension L1 of the outer diameter side guide groove 14 and the circumferential dimension L1' of the inner diameter side guide groove 15 can be suppressed, and the circumferential dimension L2 of the front-end side groove 17 can be formed to be longer than the circumferential dimensions L1 and L1' in the circumferential direction (see reference). Figure 2 Therefore, a greater number of dynamic pressure generating grooves 13 can be configured circumferentially.

[0039] The sidewall 17a on the outer diameter side of the front end side groove 17 is a roughly arc-shaped protrusion towards the outer diameter side, and its curvature is smaller and gentler than that of the sidewall 14c of the outer diameter side inlet groove 14. In addition, the curvature of the sidewall 17a of the front end side groove 17 is smaller and gentler than that of the sidewall 14d of the outer diameter side inlet groove 14.

[0040] The inner diameter sidewall 17b of the front end side groove 17 is a roughly arc-shaped protrusion extending outwards, and its curvature is smaller and gentler than that of the inner diameter side inlet groove 15 sidewall 15c. Furthermore, the curvature of the sidewall 17b of the front end side groove 17 is smaller and gentler than that of the sidewall 15d of the inner diameter side inlet groove 15.

[0041] Figure 4 This diagram is obtained by cutting along the extending direction of the portion from the inner diameter side guide groove 15 to the front end portion 17B of the front end side groove 17. Furthermore, the shape of the outer diameter side guide groove 14 in the depth direction is approximately the same as the shape of the inner diameter side guide groove 15 in the depth direction, therefore detailed description is omitted.

[0042] like Figure 4 As shown, the front end 17B side of the dynamic pressure generating groove 13 is shallower than the inner diameter side of the inlet groove 15.

[0043] Specifically, the bottom surface 15e of the inner diameter side guide groove 15 slopes towards the bottom surface 17c of the front end side groove 17, gradually becoming shallower. That is, the inner diameter end 15b of the inner diameter side guide groove 15 is the deepest. The bottom surface 15e is flat.

[0044] Furthermore, the bottom surface 17c of the front side groove 17 slopes towards the platform 12 in a manner that gradually becomes shallower. This bottom surface 17c is a flat surface.

[0045] The bottom surface 17c of the front side groove 17 is connected to the platform 12 in a smooth curve along the circumferential direction. That is, no surface raised in the depth direction is formed between the front side groove 17 and the platform 12 located in the positive rotation direction of the front side groove 17.

[0046] The inclination angle θ1 of the bottom surface 15e of the inner diameter side inlet groove 15 is larger than the inclination angle θ2 of the bottom surface 17c of the front end side groove 17. The same applies to the bottom surface 14e of the outer diameter side inlet groove 14. That is, the depth of the front end side groove 17 can be made shallower, ensuring a larger positive pressure generation area as described later.

[0047] like Figure 5 As shown in (a), the cross-section of the inner diameter side inlet groove 15 in the width direction is approximately rectangular.

[0048] In addition, such as Figure 5 As shown in (b), the cross-section of the front side groove 17 in the width direction is approximately rectangular.

[0049] Next, use Figure 6 and Figure 7 The operation of the stationary ring 10 and the rotating ring 20 when they rotate relative to each other is explained. Furthermore, in Figure 7 In this system, the density of the dot pattern represents the pressure distribution; the denser the dot pattern, the higher the pressure.

[0050] like Figure 6 As shown, when the rotating ring 20 rotates relative to the stationary ring 10 in the positive rotation direction, the fluid in the dynamic pressure generating groove 13 moves in the positive rotation direction of the rotating ring 20 by shearing with the sliding surface 21.

[0051] As a result, the fluid in the front end side groove 17 moves from the confluence section 17A to the front end 17B front end 17Ba, and the fluid in the outer diameter side inlet groove 14 and the inner diameter side inlet groove 15 moves towards the confluence section 17A. In addition, fluid is introduced from the outer space S1 into the outer diameter side inlet groove 14, and fluid is introduced from the inner space S2 into the inner diameter side inlet groove 15.

[0052] The bottom surface 14e of the outer diameter side inlet groove 14 and the bottom surface 15e of the inner diameter side inlet groove 15 are inclined in a manner that gradually becomes shallower toward the bottom surface 17c of the front end groove 17. Therefore, it is easy to guide fluid from the inner diameter end 14a of the outer diameter side inlet groove 14 and the outer diameter end 15a of the inner diameter side inlet groove 15, which are relatively deeper than other parts of the specific dynamic pressure generating groove 13, toward the front end groove 17.

[0053] In addition, the inclination angle θ2 of the bottom surface 17c of the front side groove 17 is smaller than the inclination angle θ1 of the bottom surface 14e of the outer diameter side guide groove 14 and the bottom surface 15e of the inner diameter side guide groove 15. Therefore, the depth of the front side groove 17 can be formed to be shallower over a larger range in the circumferential direction, thereby ensuring a larger positive pressure generation area in the circumferential direction.

[0054] Furthermore, since the bottom surface 14e of the outer diameter side inlet groove 14 and the bottom surface 15e of the inner diameter side inlet groove 15 are flat surfaces, the flow of fluid in the outer diameter side inlet groove 14 and the inner diameter side inlet groove 15 can be smooth.

[0055] Furthermore, the curvature of the sidewall 14c of the outer diameter side inlet groove 14 and the sidewall 15c of the inner diameter side inlet groove 15 is greater than the curvature of the sidewall 14d of the outer diameter side inlet groove 14 and the sidewall 15d of the inner diameter side inlet groove 15. The inner diameter end 14a of the outer diameter side inlet groove 14 and the outer diameter end 15a of the inner diameter side inlet groove 15 face approximately the positive rotation direction. Therefore, fluid can be efficiently introduced in the positive rotation direction.

[0056] Furthermore, the outer diameter side inlet groove 14 and the inner diameter side inlet groove 15 are arranged radially compared to the front end side groove 17, and the front end side groove 17 is arranged circumferentially compared to the outer diameter side inlet groove 14 and the inner diameter side inlet groove 15. Therefore, the circumferential lengths L1 and L1' of the outer diameter side inlet groove 14 and the inner diameter side inlet groove 15 can be suppressed, thereby ensuring a larger circumferential length L2 of the front end side groove 17, i.e., the positive pressure generation area.

[0057] In addition, since the radial lengths L10 and L20 of sidewalls 14c and 15c are shorter than the radial lengths L11 and L21 of sidewalls 14d and 15d, it is easier to introduce fluid from the outer space S1 and the inner space S2 into the front side groove 17.

[0058] Since the bottom surface 17c of the front side groove 17 gradually becomes shallower from the confluence portion 17A toward the front end portion 17B, the pressure of the fluid in the front side groove 17 gradually increases toward the front end portion 17B.

[0059] In addition, the bottom surface 17c of the front end side groove 17 is connected to the platform 12 in a smooth curve along the circumferential direction, so it is easy to guide the fluid from the front end 17Ba of the front end 17B of the front end 17B of the front end 17B toward the circumferential direction, that is, guide the fluid from the front end 17B toward the platform 12 adjacent in the circumferential direction.

[0060] In addition, since the front end 17B tapers at the front end along the positive rotation direction, a large positive pressure can be generated at the front end 17Ba of the front end 17B.

[0061] As a result, positive pressure can be generated over a large circumferential range at and near the front end 17B of the dynamic pressure generating groove 13.

[0062] Specifically, such as Figure 7 As shown, the maximum positive pressure is generated near the front end 17Ba of the front end 17B of the dynamic pressure generating channel 13, and the positive pressure gradually decreases as it diffuses outwards. In particular, the range of positive pressure generated from the front end 17Ba towards the relatively rotating upstream side is larger than that from the front end 17Ba of the front end 17B towards the relatively rotating downstream side. Furthermore, almost no positive pressure is generated near the confluence portion 17A. Thus, positive pressure is generated over a large circumferential range, and the flow of fluid from the outer diameter side inlet channel 14 and the inner diameter side inlet channel 15 towards the confluence portion 17A is not obstructed.

[0063] The force caused by the positive pressure generated at and near the front end 17B of the dynamic pressure generating groove 13 causes the sliding surfaces 11 and 21 to separate slightly, and fluid is introduced between the sliding surfaces 11 and 21, thereby improving lubricity.

[0064] Furthermore, since a large positive pressure generation area is ensured, positive pressure can be generated over a large circumferential range between sliding surfaces 11 and 21. Therefore, the oscillation of the rotating ring 20 relative to the stationary ring 10 when it floats in the separation direction of sliding surfaces 11 and 21 is small, and the sliding of sliding surfaces 11 and 21 relative to each other is stable.

[0065] Furthermore, since the curvature of the sidewalls 17a and 17b of the front end side groove 17 is smaller than the curvature of the sidewall 14d of the outer diameter side guide groove 14 and the curvature of the sidewall 15d of the inner diameter side guide groove 15, and extends in a roughly straight line, it can ensure that the platform 12 around the positive pressure generation area is larger, the oscillation of the rotating ring 20 relative to the stationary ring 10 in the direction in which the sliding surfaces 11 and 21 are separated from each other is smaller, and the sliding surfaces 11 and 21 slide stably relative to each other.

[0066] Furthermore, sidewalls 14d and 15d are connected in a roughly V-shape when viewed axially, and the front end 17Ba of the front end 17B of the dynamic pressure generating groove 13 is located downstream in the positive rotation direction at a radial position approximately the same as the valley of sidewalls 14d and 15d. This suppresses the immediate return of fluid discharged from the front end 17Ba of the front end 17B of the dynamic pressure generating groove 13 in the positive rotation direction, i.e., on the platform 12, to the downstream outer diameter side inlet groove 14 and inner diameter side inlet groove 15, thus reliably generating positive pressure between adjacent dynamic pressure generating grooves 13 in the circumferential direction.

[0067] Furthermore, in this embodiment, the cross-sectional shapes of the outer diameter side guide groove 14 and the inner diameter side guide groove 15 are shown to be approximately the same, but they can also have different depths or different bottom surface shapes, for example, one is a flat surface and the other is a curved surface.

[0068] In addition, the bottom surface 14e of the outer diameter side guide groove 14 and the bottom surface 15e of the inner diameter side guide groove 15 are not limited to flat surfaces. They can also be convex or concave on the axial side when viewed in section by becoming shallower towards the front end, or they can be stepped by becoming shallower towards the front end.

[0069] In addition, in this embodiment, the front end 17Ba of the front end 17B is arranged near the radial center of the sliding surface 11, but it can also be arranged closer to the radial side. Example 2

[0070] Next, refer to Figure 8 The sliding component of Embodiment 2 will be described. Furthermore, descriptions of structures identical or repetitive to those in Embodiment 1 will be omitted.

[0071] like Figure 8 As shown in (a), the cross-sectional shape of the portion of the dynamic pressure generating groove 213 of this embodiment 2, from the inner diameter side guide groove 215 to the front end portion 217B of the front end portion 217 along the extension direction, is approximately the same as that of the dynamic pressure generating groove 13 of embodiment 1.

[0072] like Figure 8 As shown in (b), the cross-section of the inner diameter side inlet channel 215 in the width direction is approximately U-shaped. The sidewalls 215c and 215d of the inner diameter side inlet channel 215 in the width direction have R-sections 215cr and 215dr at their upper parts, and are connected to the platform surfaces 212 located on both sides in the width direction in a smooth curve. Therefore, fluid can be easily introduced into the inner diameter side inlet channel 215 from both sides in the width direction.

[0073] Furthermore, the sidewalls 215c and 215d are also smoothly curved and connected to the bottom surface 215e of the inner diameter side inlet groove 215. As a result, the fluid is unlikely to stagnate near the bottom surface 215e of the inner diameter side inlet groove 215, allowing the fluid to flow smoothly in the positive rotation direction.

[0074] like Figure 8As shown in (c), the cross-section of the front end side groove 217 in the width direction is approximately U-shaped. The sidewalls 217a and 217b of the front end side groove 217 in the width direction have R-sections 217ar and 217br at the top, which are connected to the platform surfaces 212 located on both sides in the width direction in a smooth curve. As a result, the fluid flowing circumferentially in the front end side groove 217 is guided to both radial sides while gradually increasing in pressure towards the front end 217Ba of the front end side groove 217, thus effectively increasing the positive pressure and improving the buoyancy effect.

[0075] Furthermore, the sidewalls 217a and 217b are also smoothly curved and connected to the bottom surface 217c of the front side groove 217. As a result, fluid is unlikely to stagnate near the bottom surface 217c of the front side groove 217, allowing the fluid to flow smoothly in the positive rotation direction.

[0076] Furthermore, in this embodiment 2, the bottom surface 215e of the inner diameter side guide groove 215 and the bottom surface 217c of the front end side groove 217 are shown to have a generally U-shaped cross-section in the width direction, but they can also be generally V-shaped. In addition, the cross-section is not limited to a symmetrical shape in the width direction, and can also be formed asymmetrically. Example 3

[0077] Next, refer to Figure 9 The sliding component of Embodiment 3 will be described. Furthermore, descriptions of structures identical or repetitive to those in Embodiment 1 will be omitted.

[0078] like Figure 9 As shown, in the dynamic pressure generating groove 313 of this embodiment 3, the sidewalls 314c and 314d of the outer diameter side guide groove 314 extend in a generally parallel manner, and the sidewalls 315c and 315d of the inner diameter side guide groove 315 extend in a generally parallel manner.

[0079] This ensures stable fluid flow in the outer diameter side inlet groove 314 and the inner diameter side inlet groove 315. Example 4

[0080] Next, refer to Figure 10 The sliding component of Embodiment 4 will be described. Furthermore, descriptions of structures identical or repetitive to those in Embodiment 1 will be omitted.

[0081] like Figure 10 As shown, in the dynamic pressure generating groove 413 of this embodiment, the bottom surface 415e of the inner diameter side guide groove 415 (i.e., the bottom surface 414e of the outer diameter side guide groove 414) is connected to the bottom surface 417e of the front end side groove 417 at the same inclination angle. Therefore, the range of the positive pressure generating area can be adjusted according to the circumferential length of the dynamic pressure generating groove 413. Example 5

[0082] Next, refer to Figure 11 The sliding component of Embodiment 5 will be described. Furthermore, descriptions of structures identical or repetitive to those in Embodiment 1 will be omitted.

[0083] Reference Figure 11 In this embodiment 5, the pressure of the lubricating oil in the outer space S1 of the stationary ring 510 is higher than the pressure of the lubricating oil in the inner space S2. Furthermore, in Figure 11 In the diagram, the depth of the dynamic pressure generating groove 513 is roughly represented by the density of the dot pattern; the denser the dot pattern, the deeper the groove.

[0084] In this embodiment 5, the outer diameter side inlet groove 514 of the dynamic pressure generating groove 513 is wider and longer than the inner diameter side inlet groove 515. In other words, the volume of the outer diameter side inlet groove 514 on the high-pressure side is larger than the volume of the inner diameter side inlet groove 515 on the low-pressure side. Therefore, high-pressure lubricating oil can be easily introduced into the front end groove 517, improving the dynamic pressure generating effect.

[0085] Furthermore, the curvature of the sidewall 517a on the outer diameter side of the front end side groove 517 is greater than the curvature of the sidewall 517b on the inner diameter side. In addition, compared with the front end side groove 17 of Embodiment 1, the front end side groove 517 is wider in the radial direction, that is, in the direction orthogonal to the extension direction.

[0086] Furthermore, the dynamic pressure generating groove 513 gradually deepens from the front end 517Ba of the front end 517B of the front end side groove 517 towards the outer diameter side guide groove 514 and the inner diameter side guide groove 515. Specifically, it gradually deepens on the high-pressure side from the front end 517Ba towards the outer diameter side guide groove 514 and the inner diameter side guide groove 515. That is, the dynamic pressure generating groove 513 deepens from the inner diameter side towards the outer diameter side and towards the upstream side in the forward rotation direction; in other words, it deepens at an incline relative to the circumferential direction. Additionally, the front end side groove 517 is divided by an outer space S1, an inner space S2, and a platform 512, and communicates with the outer diameter side guide groove 514 and the inner diameter side guide groove 515. Therefore, during relative rotation, high-pressure lubricating oil is efficiently introduced along the side wall 517a of the front end side groove 517, and positive pressure is more easily generated on the side wall 17b side of the front end side groove 517. In addition, compared with the method of Example 1, the positive pressure generated at the front end 517Ba of the front end 517B is greater and the positive pressure generation area is narrower. Example 6

[0087] Next, refer to Figure 12 The sliding component of Embodiment 6 will be described. Furthermore, descriptions of structures identical or repetitive to those in Embodiment 1 will be omitted.

[0088] like Figure 12As shown, in this embodiment, the dynamic pressure generating groove 613 has multiple grooves formed on the inner circumferential surface 640a of the radial bearing 640. Figure 12 (Only one is shown in the figure). The dynamic pressure generating groove 613 includes: a side inlet groove 614 communicating with a space S10 on one side of the axial direction; a other side inlet groove 615 communicating with another space S20 on the other side of the axial direction; and a front end side groove 617 extending from the side inlet groove 614 and the other side inlet groove 615 toward the downstream side of relative rotation. The front end side groove 617 gradually becomes shallower from the side of the side inlet groove 614 and the other side inlet groove 615 toward the front end 617Ba.

[0089] Furthermore, while an example of fixing the radial bearing to the housing is shown, it can also be fixed to a rotating shaft. In this case, a hydrodynamic groove can simply be provided on the outer circumferential surface of the radial bearing.

[0090] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments. Modifications and additions that do not depart from the spirit of the present invention are also included in the present invention.

[0091] For example, in embodiments 1 to 6, a method is illustrated where the dynamic pressure generating groove gradually becomes shallower from the inlet portion toward the front end portion. However, the inlet portion can also be a deep groove with a constant depth, and the front end portion can be a shallow groove with a constant depth. That is, the dynamic pressure generating groove has at least one part with a different depth, and the front end portion can be shallower than the inlet portion.

[0092] Furthermore, in embodiments 1 to 6, an example is shown in which the outer diameter side inlet is connected to the outer space and the inner diameter side inlet is connected to the inner space. However, as long as fluid can be introduced from between the sliding surfaces, at least one of the outer diameter side inlet and the inner diameter side inlet may not be connected to the outer space or the inner space.

[0093] In addition, in embodiments 1 to 6, the front end of the dynamic pressure generating groove is smoothly connected to the platform in the circumferential direction, but a surface raised in the depth direction can also be formed between the front end of the dynamic pressure generating groove and the platform.

[0094] In addition, in embodiments 1 to 6, the outer diameter side inlet and the inner diameter side inlet are generally arc-shaped when viewed axially. However, for example, the outer diameter side inlet and the inner diameter side inlet may also extend in a straight line while tilting in the positive rotation direction, or one side may be straight and the other arc-shaped.

[0095] In addition, in the embodiments 1 to 6, a method of arranging 10 dynamic pressure generating grooves evenly in the circumferential direction is illustrated, but it can also be freely changed according to the usage environment, etc.

[0096] Furthermore, in the embodiments 1 to 6, the example of the sliding member being ring-shaped was used, but it is not limited to this. For example, the sliding member may also be plate-shaped.

[0097] Furthermore, in the embodiments 1 to 6, a sliding component for a thrust bearing was described, but the sliding component can also be used in mechanical seals, sliding bearings, etc. for automobiles, general industrial machinery, etc.

[0098] In addition, the fluid used for lubrication can be a liquid or a gas, or a mist formed by a mixture of liquid and gas.

[0099] Furthermore, in embodiments 1 to 6, the same fluid is shown in the outer space and the inner space, but different fluids that are allowed to mix and with different pressures are also possible.

[0100] Furthermore, in embodiments 1 to 6, a method in which positive pressure is not generated at the confluence of the front-end side groove is illustrated, but positive pressure can also be generated at the confluence. Explanation of reference numerals in the attached figures

[0101] 1: Rotating shaft; 3: Thrust bearing (sliding component); 10: Stationary ring; 11: Sliding surface; 12: Platform; 13: Dynamic pressure generating groove; 14: Outer diameter side inlet groove (inlet part); 14e: Bottom surface; 15: Inner diameter side inlet groove (inlet part); 15e: Bottom surface; 17: Front end side groove; 17A: Confluence part; 17B: Front end; 17Ba: Front end; 17c: Bottom surface; S1: Outer space; S2: Inner space; θ1, θ2: Inclination angle.

Claims

1. A sliding member disposed between a housing and a shaft inserted into the housing, wherein a pair of sliding surfaces rotate relative to each other, characterized in that, At least one sliding surface has a dynamic pressure generating groove, the dynamic pressure generating groove having an inlet portion communicating with one space on one side, an inlet portion communicating with another space on the other side, and a front end portion where the two inlet portions merge on the downstream side during relative rotation. Compared to the inlet side on one side and the inlet side on the other side of the dynamic pressure generating groove, the front end side of the dynamic pressure generating groove is shallower.

2. The sliding component according to claim 1, characterized in that, The dynamic pressure generating groove gradually becomes shallower from at least one of the inlet portions toward the front end portion.

3. The sliding component according to claim 1, characterized in that, The bottom surface of the front end is curved in the circumferential direction and connected to the platform.

4. The sliding component according to claim 1, characterized in that, The bottom surface of the front end is connected to the platform in a radially curved shape.

5. The sliding component according to claim 2, characterized in that, At least one of the bottom surfaces of the inlet portion has a larger inclination angle than the bottom surface of the front end portion.

6. The sliding component according to claim 1, characterized in that, At least one of the inlet portions is arranged radially, and the front end portion is arranged circumferentially.

7. The sliding component according to any one of claims 1 to 6, characterized in that, The front end tapers towards the front end in the positive rotation direction.

8. The sliding component according to claim 1, characterized in that, Compared to the inlet portion on the other side, the inlet portion on this side is wider and longer.

9. The sliding component according to claim 8, characterized in that, The inlet portion on one side of the front end is deeper than the inlet portion on the other side of the front end.

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