Sliding parts

Abstract

Provided is a sliding component capable of discharging contamination to a gap between sliding surfaces.　A sliding component 10 which is disposed at a relatively rotating position of a rotary machine, which relatively slides with respect to another sliding component 20, and which has a sliding surface 11 provided with a fluid introduction groove 14 communicating with at least one from among a space on a sealed fluid side and a space on a leakage side and a dynamic pressure generation groove 15 communicating with the fluid introduction groove 14 and extending in the circumferential direction. Both side edges 15e, 15f and a terminal edge 15g of the dynamic pressure generation groove 15 are continuous in a curved form in plan view.

Description

[[Technical Field]]

[0001] The present invention relates to a sliding component used in a shaft sealing device that seals a space between a rotating shaft of a rotating machine and a case. [[Background Art]]

[0002] As a shaft sealing device for preventing leakage of a sealed fluid around a rotating shaft in a rotating machine, for example, a mechanical seal including a pair of annular sliding components that rotate relatively and slide against each other with their sliding surfaces is known. In recent years, for such mechanical seals, reduction of energy lost due to sliding has been demanded for environmental protection and other purposes, and some sliding components have a positive pressure generating groove provided on the sliding surface of the sliding component that communicates with the sealed liquid side and has one end closed on the sliding surface.

[0003] For example, in the mechanical seal disclosed in Patent Document 1, on the sliding surface of one sliding component, there are provided a fluid introduction groove that extends in the radial direction, communicates with the sealed liquid side and does not communicate with the leakage side, and a positive pressure generating groove that communicates with the fluid introduction groove and extends in the relative rotation direction. A plurality of positive pressure generating mechanisms constituted by the above are provided in the circumferential direction via land portions. According to this configuration, when the sliding components rotate relative to each other, the sealed fluid is introduced into the positive pressure generating groove through the fluid introduction groove, the sealed fluid concentrates on the wall at the end of the positive pressure generating groove in the relative rotation direction to generate positive pressure, which separates the sliding surfaces from each other, and a fluid film of the sealed fluid is formed on the sliding surfaces, thereby improving lubricity and achieving low friction. [[Prior Art Documents]] [[Patent Documents]]

[0004] [[Patent Document 1]] Japanese Patent No. 6444492 (Page 12, Figure 7) [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] In the sliding parts described in Patent Document 1, the sealed fluid flows along a pair of side surfaces of the positive pressure generating groove and is then supplied between the sliding parts from the end surface and its vicinity, thereby reducing friction between the sliding parts. However, in sliding parts like those described in Patent Document 1, a nearly right-angle corner is formed at the boundary between the side surface and the end surface that constitute the positive pressure generating groove. When the sealed fluid moves from the fluid introduction groove toward the end of the positive pressure generating groove, vortices are generated near this corner, creating an area where the flow of the sealed fluid is difficult to generate, and there is a risk that contaminants contained in the sealed fluid will stagnate and accumulate in this area. Contaminants accumulated at the corner of the positive pressure generating groove may affect the performance of the positive pressure generating groove or may cause abrasive wear and damage to the sliding surface. In this application, "contaminants" is an abbreviation of "contamination" and means "particulate foreign matter" such as fine particulate conductive foreign matter.

[0006] This invention was made in view of these problems, and aims to provide a sliding component that can discharge contaminants between sliding surfaces. [Means for solving the problem]

[0007] To solve the aforementioned problems, the sliding component of the present invention is A sliding component positioned at a relative rotating part of a rotating machine, which slides relative to other sliding components, and whose sliding surface is provided with a fluid introduction groove that communicates with at least one of the spaces on the sealed fluid side or the leaking side, and a dynamic pressure generating groove that communicates with the fluid introduction groove and extends in the circumferential direction, The side edges and the closing edge of the aforementioned dynamic pressure generating groove are curved and continuous in a plan view. According to this, when positive pressure is generated in the dynamic pressure generating groove, the fluid moves smoothly along the curved portion where both side edges and the closing edge are continuous at the closed section of the dynamic pressure generating groove, and flows out between the sliding surfaces from the closing edge and its vicinity. As a result, contaminants contained in the fluid can be discharged between the sliding surfaces without accumulating at the closed section of the dynamic pressure generating groove.

[0008] The side surface extending in the depth direction from the side edge and the closing surface extending in the depth direction from the closing edge may be curved and continuous. According to this, the side surface extending in the depth direction from the side edge and the closing surface extending in the depth direction from the closing edge are curved and continuous, allowing fluid to move smoothly along the depth direction of the closing portion of the dynamic pressure generating groove.

[0009] The two aforementioned side surfaces and the closing surface may be continuous with a curved surface having a radius of curvature in a plan view. According to this, contaminants can be smoothly moved along a surface with a single curvature.

[0010] The aforementioned closing surface may be a curved surface having a radius of curvature. According to this, the contaminant can be smoothly moved along a closure surface of a single curvature.

[0011] The bottom surface and the closing surface constituting the dynamic pressure generating groove are curved and continuous in cross-sectional view. According to this, near the occluded surface, the bottom surface guides the movement of the fluid toward the sliding surface, making it easier to discharge contaminants between the sliding surfaces.

[0012] The fluid introduction groove communicates with the space on the sealed fluid side, and the sliding surface may be provided with spiral grooves that communicate with the leaking space but not with the space on the sealed fluid side. According to this design, the spiral groove supplies the fluid from the leaking side between the sliding surfaces, thereby suppressing the movement of contaminants discharged between the sliding surfaces into the space on the leaking side. [Brief explanation of the drawing]

[0013] [Figure 1] This is a longitudinal cross-sectional view showing an example of a mechanical seal in Embodiment 1 of the present invention. [Figure 2] This is a view of the sliding surface of the stationary sealing ring in Example 1, seen from the axial direction. [Figure 3] This is an enlarged view of the sliding surface of the stationary sealing ring in Example 1, as seen from the axial direction. [Figure 4] It is a plan view showing the shape of the closed portion of the dynamic pressure generating groove in Example 1. [Figure 5] It is a cross-sectional view showing the shape of the closed portion of the dynamic pressure generating groove in Example 1. [Figure 6] It is a plan view showing the shape of the closed portion of the dynamic pressure generating groove in Example 2 of the present invention. [Figure 7] It is a plan view showing the shape of the closed portion of the dynamic pressure generating groove in Example 3 of the present invention. [Figure 8] It is a plan view showing the shape of the closed portion of the dynamic pressure generating groove in Example 4 of the present invention. [Figure 9] It is a plan view showing the shape of the closed portion of the dynamic pressure generating groove in Example 5 of the present invention. [Figure 10] It is an enlarged view of the sliding surface of the stationary seal ring in Example 6 of the present invention as viewed from the axial direction. [Figure 11] It is an enlarged view of the sliding surface of the stationary seal ring in Example 7 of the present invention as viewed from the axial direction. [Figure 12] It is an enlarged view of the sliding surface of the stationary seal ring in Example 8 of the present invention as viewed from the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0014] Modes for carrying out the sliding component according to the present invention will be described below based on examples. EXAMPLES

[0015] The sliding component according to Example 1 will be described with reference to FIG. 1 to FIG. 5. In the present example, the sealed fluid F is present in the inner space S1 of the mechanical seal, and the atmosphere A is present in the outer space S2. The description is given on the premise that the inner diameter side of the sliding component constituting the mechanical seal is the sealed fluid side (high pressure side), and the outer diameter side is the leakage side (low pressure side). For convenience of explanation, in the drawings, dots may be added to grooves and the like formed on the sliding surface.

[0016] The automotive mechanical seal shown in Figure 1 is an outside-type seal that seals the fluid to be sealed in an inner space S1 that would otherwise leak from the inner diameter side to the outer diameter side of the sliding surface, while the outer space S2 is open to the atmosphere A. In this embodiment, the example shown is one in which the fluid to be sealed is a high-pressure liquid and the atmosphere A is a gas at a lower pressure than the fluid to be sealed F.

[0017] The mechanical seal mainly consists of a rotating sealing ring 20 as the other sliding component and a stationary sealing ring 10 as the other sliding component. The rotating sealing ring 20 is annular in shape and is mounted on the rotating shaft 1 via a sleeve 2 so as to be rotatable with the rotating shaft 1. The stationary sealing ring 10 is annular in shape and is mounted on a seal cover 5 fixed to the housing 4 of the equipment to be mounted, in a non-rotatable state and so as to be movable in the axial direction. The stationary sealing ring 10 is biased in the axial direction by an elastic member 7 so that the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 slide in close contact with each other. The sliding surface 21 of the rotating sealing ring 20 is a flat surface, and there are no grooves or other recesses on this flat surface.

[0018] The stationary sealing ring 10 and the rotating sealing ring 20 are typically formed from two SiC (hard material) components or a combination of SiC (hard material) and carbon (soft material), but are not limited to these; any sliding material used for mechanical seals is applicable. SiC can be sintered using boron, aluminum, carbon, etc., as sintering aids, or from materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC made of SiC and Si, SiC-TiC, SiC-TiN, etc. Carbon can be a mixture of carbonaceous and graphite, as well as resin-molded carbon and sintered carbon. In addition to the sliding materials mentioned above, metal materials, resin materials, surface modification materials (coating materials), and composite materials are also applicable.

[0019] As shown in Figures 2 and 3, the rotating sealing ring 20, which is the mating sealing ring, slides relative to the stationary sealing ring 10 in a clockwise direction as indicated by the solid arrows.

[0020] Multiple dynamic pressure generating mechanisms 13 are evenly arranged in the circumferential direction on the inner diameter side of the sliding surface 11 of the stationary sealing ring 10 (eight in this embodiment).

[0021] Furthermore, the portion of the sliding surface 11 other than the dynamic pressure generating mechanism 13 forms a flat land 12. The flat surface of the land 12 functions as a sliding surface that substantially slides against the sliding surface 21 of the rotating sealing ring 20.

[0022] As shown in Figure 3, the dynamic pressure generation mechanism 13 consists of a fluid introduction groove 14 and a Rayleigh step 15 which serves as a dynamic pressure generation groove. The fluid introduction groove 14 extends radially, communicating with the inner space S1 but not with the outer space S2. The Rayleigh step 15 extends circumferentially from the outer diameter side of the fluid introduction groove 14 in a clockwise direction, concentric with the stationary sealing ring 10. The depth of the fluid introduction groove 14 is greater than the depth of the Rayleigh step 15.

[0023] The fluid introduction groove 14 consists of a bottom surface 14a, side surfaces 14b and 14c, and an outer diameter end surface 14d. The bottom surface 14a extends radially parallel to the flat surface of the land 12. The side surfaces 14b and 14c rise from both circumferential edges of the bottom surface 14a. The outer diameter end surface 14d rises from the outer diameter end of the bottom surface 14a and connects the side surfaces 14b and 14c. An opening 14A communicating with the Rayleigh step 15 is formed in the side surface 14b. In addition, an opening 14B communicating with the internal space S1 is formed on the inner diameter side of the fluid introduction groove 14. The bottom surface 14a may be inclined toward the outer diameter side so as to approach the land 12, i.e., so as to become shallower.

[0024] Referring to FIG. 4 and FIG. 5, the Rayleigh step 15 is mainly composed of a bottom surface 15a, side surfaces 15b, 15c, and an end surface 15d serving as a blocking surface on the downstream side of relative rotation. The bottom surface 15a extends radially in parallel with the flat surface of the land 12. The side surfaces 15b and 15c rise from both circumferential edges of the bottom surface 15a toward the flat surface of the land 12. The end surface 15d on the downstream side of relative rotation is continuous with the side surfaces 15b and 15c from the circumferential edge of the bottom surface 15a. Hereinafter, a portion near the end surface 15d in the Rayleigh step 15 is referred to as an end portion 15A, and the end portion 15A has a blocked shape. That is, the end portion 15A functions as a blocking portion.

[0025] As shown in FIG. 4, the side surfaces 15b and 15c are arc surfaces that extend parallel to each other mainly in the relative rotation direction, and the end surface 15d is a flat surface that extends mainly in a direction intersecting the relative rotation direction. The separation width between the side surfaces 15b and 15c, that is, the radial width dimension W of the Rayleigh step 15, is constant in the circumferential direction.

[0026] Further, as shown in FIG. 5, the separation width between the bottom surface 15a and the flat surface of the land 12, that is, the depth dimension D of the Rayleigh step 15, is constant in the circumferential direction.

[0027] Further, as shown in FIG. 4 and FIG. 5, the depth dimension D of the Rayleigh step 15 is smaller than the width dimension W of the Rayleigh step 15 (D<W). Preferably, the depth dimension D of the Rayleigh step 15 is 1 / 10 or less of the width dimension W of the Rayleigh step 15.

[0028] The side surfaces 15b and 15c have side edges 15e and 15f at their upper ends, specifically at portions connected to the flat surface of the land 12, and the end surface 15d has an end edge 15g as a blocking edge at its upper end, specifically at a portion connected to the flat surface of the land 12. In other words, the side surfaces 15b and 15c extend in the depth direction from the side edges 15e and 15f, and the end surface 15d extends in the depth direction from the end edge 15g.

[0029] In particular, as shown in Figure 4, these side edges 15e, 15f and terminal edge 15g are curved and continuous in plan view. More specifically, the sides 15b and 15c having side edges 15e and 15f are continuous with the upper edges 15m and 15n of curved surfaces 15h and 15j, which have the same radius of curvature R1 in plan view, at both radial ends of the terminal surface 15d having terminal edge 15g. The dashed-dotted circles shown adjacent to the curved surfaces 15h and 15j are imaginary lines to explain the radius of curvature R1. Furthermore, imaginary lines like the ones described above may also be illustrated below to explain the radius of curvature.

[0030] The outer diameter surface 15h is convex in a plan view on the downstream outer diameter side of relative rotation, i.e., the clockwise outer diameter side. The inner diameter surface 15j is convex in a plan view on the downstream inner diameter side of relative rotation, i.e., the clockwise inner diameter side. In other words, the centers of curvature of the curved surfaces 15h and 15j are located inside the Rayleigh step 15.

[0031] Furthermore, as shown in Figure 5 in particular, the bottom surface 15a and the end surface 15d are curved and continuous in cross-sectional view. More specifically, the bottom surface 15a and the end surface 15d are continuous in cross-sectional view by a curved surface 15k having a radius of curvature R2. In cross-sectional view, the curved surface 15k is convex in the depth direction on the downstream side of relative rotation, that is, in the clockwise direction and away from the sliding surface 21 of the rotating sealing ring 20. In other words, the center of curvature of the curved surface 15k is located inside the Rayleigh step 15.

[0032] Furthermore, the radius of curvature R1 of surfaces 15h and 15j is greater than the radius of curvature R2 of surface 15k (R1 > R2). In other words, surfaces 15h and 15j are more gently curved than surface 15k.

[0033] Furthermore, the radius of curvature R1 is within the range of 1 / 3 to 3 times the depth dimension D of the Rayleigh step 15.

[0034] Furthermore, the radius of curvature R1 is 10 μm or greater (R1 ≥ 10 μm).

[0035] Next, the operation of the stationary sealing ring 10 and the rotating sealing ring 20 during relative rotation will be explained using Figures 3 to 5. Note that the flow of the sealed fluid F and the atmosphere A in Figure 3 are shown schematically without specifying the relative rotation speed of the rotating sealing ring 20.

[0036] First, when the rotating sealing ring 20 is not rotating and is stopped, the sealed fluid F flows into the fluid introduction groove 14. Furthermore, since the stationary sealing ring 10 is biased toward the rotating sealing ring 20 by the elastic member 7, the sliding surfaces 11 and 21 are in contact with each other, and there is almost no leakage of the sealed fluid F between the sliding surfaces 11 and 21 into the outer space S2.

[0037] As shown in Figure 3, when the rotating sealing ring 20 is rotating relative to the stationary sealing ring 10, the sealed fluid F in the Rayleigh step 15 moves in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21, and the sealed fluid F in the inner space S1 is drawn into the fluid introduction groove 14. That is, within the fluid introduction groove 14, the sealed fluid F moves from the fluid introduction groove 14 toward the downstream end 15A in the direction of relative rotation of the Rayleigh step 15, as shown by arrow H1.

[0038] As the sealed fluid F moves toward the terminal end 15A of the Rayleigh step 15, its pressure increases at and near the terminal end 15A of the Rayleigh step 15. In other words, positive pressure is generated at and near the terminal end 15A of the Rayleigh step 15.

[0039] Because the Rayleigh step 15 is shallow, even with a small amount of movement of the sealed fluid F due to the low rotational speed of the rotating sealing ring 20, positive pressure is generated at the end portion 15A of the Rayleigh step 15 and its vicinity.

[0040] Furthermore, the positive pressure generated at and near the end 15A of the Rayleigh step 15 causes a slight separation between the sliding surfaces 11 and 21 (see Figure 5). As a result, the sealed fluid F from the dynamic pressure generation mechanism 13, indicated by arrow H2, flows into the space between the sliding surfaces 11 and 21. This interposition of the sealed fluid F between the sliding surfaces 11 and 21 improves lubrication even at low rotational speeds and suppresses wear between the sliding surfaces 11 and 21. Moreover, because the floating distance between the sliding surfaces 11 and 21 is small, little of the sealed fluid F leaks into the outer space S2. In addition, since a fluid introduction groove 14 is provided, a large amount of the sealed fluid F can be retained.

[0041] As shown in Figure 4, the sealed fluid F moving along the sides 15b and 15c at the end portion 15A of the Rayleigh step 15 moves along the curved surfaces 15h and 15j which are curved in plan view. A portion of it flows beyond the curved surfaces 15h and 15j into the sliding surfaces 11 and 21, while another portion is collected in the widthwise center of the Rayleigh step 15 and flows beyond the end portion 15d into the sliding surfaces 11 and 21.

[0042] Furthermore, microscopically, in a plan view, the point at which the sealed fluid F experiences the highest pressure at the terminal portion 15A changes in the width direction over time. The sealed fluid F moves along the curved surfaces 15h, 15j and the terminal surface 15d, and since the curved surfaces 15h, 15j and the terminal surface 15d are smoothly connected, contaminants are easily discharged between the sliding surfaces 11 and 21 without accumulating.

[0043] Furthermore, as shown in Figure 5, since the bottom surface 15a and the end surface 15d are continuous due to the curved surface 15k, the sealed fluid F can move smoothly towards the sliding surfaces 11 and 21.

[0044] As explained above, the side edges 15e, 15f and the terminal edge 15g of the Rayleigh step 15 are continuous with curved surfaces 15h, 15j in a plan view. As a result, at the terminal portion 15A of the Rayleigh step 15, the sealed fluid F moves smoothly along the curved surfaces 15h, 15j that are continuous with the side edges 15e, 15f and the terminal edge 15g. Therefore, contaminants contained in the sealed fluid F do not accumulate at the terminal portion 15A of the Rayleigh step 15, but can be discharged from inside the Rayleigh step 15 to the sliding surfaces 11, 21.

[0045] In other words, since no corners are formed in a plan view between the side edges 15e, 15f and the terminal edge 15g, vortices are less likely to form between the side edges 15e, 15f and the terminal edge 15g at the terminal portion 15A of the Rayleigh step 15, and the formation of a region where contamination is likely to accumulate at the terminal portion 15A of the Rayleigh step 15 can be suppressed.

[0046] Furthermore, because the side surfaces 15b and 15c extending in the depth direction from the side edges 15e and 15f toward the bottom surface 15a, and the end surface 15d extending in the depth direction from the end edge 15g toward the bottom surface 15a are curved and continuous, the sealed fluid F can be smoothly moved along the depth direction of the end portion 15A of the Rayleigh step 15.

[0047] Furthermore, both side surfaces 15b, 15c and the end surface 15d are continuous with curved surfaces 15h, 15j having a single radius of curvature R1 in plan view. This allows contaminants to move smoothly along the curved surfaces 15h, 15j with a single radius of curvature, with some being discharged from the side surfaces 15b, 15c between the sliding surfaces 11, 21 and collected in the center of the Rayleigh step 15 in the width direction, while the remaining portion is discharged from the end surface 15d between the sliding surfaces 11, 21.

[0048] Furthermore, the bottom surface 15a and the end surface 15d that constitute the Rayleigh step 15 are curved and continuous in cross-sectional view. As a result, in the vicinity of the end surface 15d, the curved surface 15k between the bottom surface 15a and the end surface 15d guides the movement of the sealed fluid F towards the sliding surfaces 11 and 21, making it easier to discharge contaminants between the sliding surfaces 11 and 21. In other words, the accumulation of contaminants at the boundary between the bottom surface 15a and the end surface 15d can be suppressed.

[0049] Furthermore, the Rayleigh step 15 extends circumferentially from a fluid introduction groove 14 that communicates with the inner space S1 but not with the outer space S2. This allows the sealed fluid F to flow stably from the fluid introduction groove 14, which is deeper than the Rayleigh step 15, into the Rayleigh step 15.

[0050] In this embodiment 1, the curved surfaces 15h and 15j are shown as being formed in the shape of a circular arc with a single radius of curvature R1 in a plan view. However, they may also be shaped as part of a parabola, part of an ellipse, part of a sine wave, etc., in a plan view.

[0051] In this embodiment 1, the curved surface 15k is shown as being formed in the shape of a circular arc with a single radius of curvature R2 in cross-sectional view. However, it may also be formed in the shape of a part of a parabola, a part of an ellipse, a part of a sine wave, etc., in cross-sectional view. [Examples]

[0052] Next, the sliding parts according to Example 2 will be described with reference to Figure 6. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.

[0053] In this embodiment 2, the end surface 215d of the Rayleigh step 215 is approximately semicircular in plan view. More specifically, the end surface 215d has a single radius of curvature R3 and is continuous with the sides 215b and 215c.

[0054] According to this, the sealed fluid F moving along the sides 215b, 215c of the Rayleigh step 215 moves smoothly toward the center in the width direction of the Rayleigh step 215 by the end surface 215d, and is discharged beyond the end surface 215d into the space between the sliding surfaces 11, 21 (see Figure 5). [Examples]

[0055] Next, the sliding parts according to Embodiment 3 will be described with reference to Figure 7. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0056] In this embodiment 3, the end surface 315d of the Rayleigh step 315 has a substantially semi-elliptical shape in plan view and is continuous with the sides 315b and 315c. As a result, the sealed fluid F moving along the sides 315b and 315c of the Rayleigh step 315 moves smoothly toward the center in the width direction of the Rayleigh step 315 by the end surface 315d and is discharged beyond the end surface 315d into the space between the sliding surfaces 11 and 21 (see Figure 5). Furthermore, compared to the Rayleigh step 215 of embodiment 2, the radius of curvature of the final end portion, which is located furthest downstream in relative rotation, is smaller, making it easier to generate positive pressure at this final end portion. [Examples]

[0057] Next, the sliding parts according to Embodiment 4 will be described with reference to Figure 8. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0058] In this embodiment 4, the Rayleigh step 415 has an outer diameter side surface 415b that extends downstream in the relative rotational direction compared to the inner diameter side surface 415c. The end surface 415d is composed of an inclined surface portion 415e, a curved surface portion 415h, and a curved surface portion 415j. The inclined surface portion 415e is inclined in the circumferential direction to connect the sides 415b and 415c and extends linearly in the radial direction. The curved surface portion 415h connects the side surface 415b and the inclined surface portion 415e. The curved surface portion 415j connects the side surface 415c and the inclined surface portion 415e.

[0059] The outer diameter curved surface portion 415h has one radius of curvature R4, and the inner diameter curved surface portion 415j has one radius of curvature R5 which is larger than radius of curvature R4 (R4 <R5)。

[0060] The sealed fluid F within the Rayleigh step 415 is guided outward by the inclined surface portion 415e of the end surface 415d during relative rotation, and is mainly discharged from near the curved surface portion 415h to the area between the sliding surfaces 11 and 21 (see Figure 5).

[0061] Since the radius of curvature R4 of the curved surface 415h is smaller than the radius of curvature R5 of the curved surface 415j, positive pressure is more easily generated near the curved surface 415h than near the curved surface 415j. Furthermore, because the curved surface 415j is more gently curved than the curved surface 415h, the generation of positive pressure in the curved surface 415j is suppressed while the sealed fluid F can be smoothly moved toward the inclined surface 415e. [Examples]

[0062] Next, the sliding parts according to Example 5 will be described with reference to Figure 9. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.

[0063] The terminal surface 515d of the Rayleigh step 515 in this embodiment 5 is composed of a first inclined surface portion 515e, a second inclined surface portion 515f, and a curved surface portion 515h. The first inclined surface portion 515e extends linearly from the side surface 515b, inclined toward the inner diameter downstream of relative rotation. The second inclined surface portion 515f extends linearly from the side surface 515c, inclined toward the outer diameter downstream of relative rotation. The curved surface portion 515h is continuous with the circumferential downstream ends of the first inclined surface portion 515e and the second inclined surface portion 515f.

[0064] During relative rotation, the sealed fluid F within the Rayleigh step 515 is guided by the side surface 515b and the second inclined surface 515f toward the first inclined surface 515e and the curved surface 515h at the end surface 515d, and is mainly discharged beyond the first inclined surface 515e and the curved surface 515h toward the sliding surfaces 11 and 21 (see Figure 5).

[0065] Furthermore, the boundary portions between the side surface 515b and the first inclined surface portion 515e, and the boundary portions between the side surface 515c and the second inclined surface portion 515f are curved, allowing the sealed fluid F to move smoothly along these boundary portions, thereby suppressing the accumulation of contaminants. Note that the boundary portions between the side surface 515b and the first inclined surface portion 515e, and the boundary portions between the side surface 515c and the second inclined surface portion 515f may be continuous at an obtuse angle. [Examples]

[0066] Next, the sliding parts according to Embodiment 6 will be described with reference to Figure 10. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0067] The sliding surface 11 of the stationary sealing ring 10' in this embodiment 6 is provided with a plurality of dynamic pressure generating mechanisms 13 and a plurality of spiral grooves 16. The dynamic pressure generating mechanisms 13 have the same configuration as the mechanical seal in embodiment 1.

[0068] The spiral grooves 16 are evenly distributed in the circumferential direction on the outer diameter side of the sliding surface 11. The portions of the sliding surface 11 other than the dynamic pressure generating mechanism 13 and the spiral grooves 16 form flat lands 12. Specifically, the lands 12 have land portions between circumferentially adjacent dynamic pressure generating mechanisms 13, land portions between circumferentially adjacent spiral grooves 16, and land portions between radially spaced dynamic pressure generating mechanisms 13 and spiral grooves 16. These land portions are arranged on the same plane and constitute the flat surface of the land 12.

[0069] The spiral groove 16 extends in an arc shape, inclined clockwise from the outer diameter side to the inner diameter side. This spiral groove 16 communicates with the outer space S2 but does not communicate with the inner space S1.

[0070] The spiral groove 16 is formed to a constant depth in the circumferential direction. The spiral groove 16 is not limited to extending in an arc shape with an inclination; it may also extend in a straight line.

[0071] The spiral groove 16 is composed of a bottom surface 16a, side surfaces 16b and 16c, and an end surface 16d. The bottom surface 16a extends radially parallel to the flat surface of the land 12. The side surfaces 16b and 16c rise from both circumferential edges of the bottom surface 16a. The end surface 16d connects the inner diameter ends of the bottom surface 16a and the side surfaces 16b and 16c. An opening 16A is formed on the outer diameter side of the spiral groove 16, which communicates with the outer space S2.

[0072] Next, the operation of the stationary sealing ring 10' and the rotating sealing ring 20 during relative rotation will be described.

[0073] At low speeds immediately after the rotating sealing ring 20 begins to rotate relative to the stationary sealing ring 10, a positive pressure is generated at the end 15A of the Rayleigh step 15 and in its vicinity, as described above.

[0074] On the other hand, in the spiral groove 16, when the relative rotation speed between the rotating sealing ring 20 and the stationary sealing ring 10' is low, the atmosphere A does not become sufficiently dense within the spiral groove 16, and high positive pressure is not generated. The force due to the positive pressure generated by the spiral groove 16 is relatively small compared to the force due to the positive pressure generated at and near the end portion 15A of the Rayleigh step 15. Therefore, when the rotating sealing ring 20 rotates at a low speed, the force due to the positive pressure generated at and near the end portion 15A of the Rayleigh step 15 is the main force that separates the sliding surfaces 11 and 21 from each other.

[0075] As the relative rotational speed of the rotating sealing ring 20 increases, as shown in Figure 10, the air A inside the spiral groove 16 moves in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21, and air A in the outer space S2 is drawn into the spiral groove 16. That is, within the spiral groove 16, a large amount of air A moves from the outer diameter opening 16A toward the inner diameter end 16B, as shown by arrow L1.

[0076] As the air A moves toward the inner diameter end 16B of the spiral groove 16, its pressure increases at and near the inner diameter end 16B of the spiral groove 16. In other words, positive pressure is generated at and near the inner diameter end 16B of the spiral groove 16.

[0077] In this way, the positive pressure force generated at the end portion 15A of the Rayleigh step 15 and its vicinity is added to the positive pressure force generated at the inner diameter end portion 16B of the spiral groove 16 and its vicinity, causing the sliding surfaces 11 and 21 to separate further compared to when moving at low speeds. As a result, air A from within the spiral groove 16, mainly indicated by arrow L2, flows into the space between the sliding surfaces 11 and 21.

[0078] The air A inside the spiral groove 16, indicated by arrow L2, acts to push the sealed fluid F near the inner diameter end 16B of the spiral groove 16 back towards the inner space S1, so that little of the sealed fluid F leaks into the spiral groove 16 or into the outer space S2.

[0079] In this embodiment, the mechanical seal is designed so that, at high-speed rotation, the positive pressure generation capacity of the entire spiral groove 16 is sufficiently greater than the positive pressure generation capacity of the entire dynamic pressure generation mechanism 13. As a result, ultimately, only air A is present between the sliding surfaces 11 and 21, i.e., gaseous lubrication is achieved.

[0080] Furthermore, the sealed fluid F in the inner space S1 is a liquid, and the fluid in the outer space S2, which is the leakage side, is the atmosphere A, i.e., a gas. At low rotational speeds, the liquid lubricates the sliding surfaces 11 and 21, and at high rotational speeds, the gas lubricates the sliding surfaces 11 and 21. In other words, lubrication between the sliding surfaces 11 and 21 can be appropriately performed according to the relative rotational speed of the stationary sealing ring 10 and the rotating sealing ring 20. [Examples]

[0081] Next, the mechanical seal according to Example 7 will be described with reference to Figure 11. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.

[0082] The mechanical seal of this embodiment 7 has a dynamic pressure generating mechanism 130 formed on the outer diameter side of the sliding surface of the stationary sealing ring, which has a fluid introduction groove 140 and a dynamic pressure generating groove 150. The operation of the stationary sealing ring 10 and the rotating sealing ring 20 during relative rotation is substantially the same as in embodiment 1 except for the change in inner and outer diameters, so its explanation is omitted. [Examples]

[0083] Next, the mechanical seal according to Example 8 will be described with reference to Figure 12. Note that the description of components that are identical to those in Example 6 and therefore redundant will be omitted.

[0084] In this embodiment 8, the mechanical seal has a dynamic pressure generating mechanism 130 formed on the outer diameter side of the sliding surface of the stationary sealing ring, which has a fluid introduction groove 140 and a dynamic pressure generating groove 150, and a spiral groove 160 formed on the inner diameter side. The operation of the stationary sealing ring 10 and the rotating sealing ring 20 during relative rotation is substantially the same as in embodiment 6, except for the change in inner and outer diameters, so its explanation is omitted.

[0085] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.

[0086] For example, in the above embodiment, a mechanical seal for automobiles was described as an example of a sliding part, but other mechanical seals such as those for general industrial machinery may also be used.

[0087] Furthermore, while examples 1 to 8 described above illustrate the provision of dynamic pressure generating grooves and fluid introduction grooves on a stationary sealing ring, dynamic pressure generating grooves and fluid introduction grooves may also be provided on a rotating sealing ring. In other words, the sliding component of the present invention may be either a stationary sealing ring or a rotating sealing ring.

[0088] Furthermore, in Examples 1 to 8, the sealed fluid side has been described as the high-pressure side and the leak side as the low-pressure side, but the sealed fluid side and the leak side may be at approximately the same pressure. When the sealed fluid side and the leak side are at approximately the same pressure, it is preferable to form the dynamic pressure generating groove on the leak side deeper than the dynamic pressure generating groove on the sealed fluid side, so that positive pressure is generated in the dynamic pressure generating groove at low rotation speeds and at high rotation speeds.

[0089] Furthermore, although the sealed fluid F was described as a high-pressure liquid in Examples 1 to 8, it is not limited to this and may be a gas or a low-pressure liquid, or it may be a mist-like mixture of liquid and gas.

[0090] Furthermore, although the leakage fluid in Examples 1 to 8 was described as atmospheric air A, which is a low-pressure gas, it is not limited to this; it may also be a liquid or a high-pressure gas, or a mist-like mixture of liquid and gas.

[0091] Furthermore, in the above embodiments 1 to 8, the fluid introduction groove and the dynamic pressure generation groove were described as being provided to communicate with the space S1 on the sealed fluid F side, but they are not limited to this configuration and may be provided to communicate with the leakage side space S2.

[0092] Furthermore, while embodiments 1 to 8 illustrate a form in which the Rayleigh step extends in an arc shape, it may also extend in a straight line. Also, the Rayleigh step is not limited to being provided concentrically with the stationary sealing ring, but may be inclined in the circumferential direction. That is, the side surface may mainly extend in the relative rotational direction, and the closing surface may mainly extend in a direction intersecting the relative rotational direction.

[0093] Furthermore, while embodiments 1 to 8 above illustrate a configuration in which both sides of the Rayleigh step extend vertically in the depth direction from both side edges, for example, the width of both sides may be inclined to narrow in the depth direction from both side edges.

[0094] Furthermore, while embodiments 1 to 8 described above illustrate a configuration in which the closing surface of the Rayleigh step extends vertically from the closing edge to the curved surface on the bottom side, it may also extend from the closing edge to the curved surface on the bottom side, with a slope that becomes shallower toward the upstream side of relative rotation.

[0095] Furthermore, while embodiments 1 to 8 illustrate a configuration in which the bottom surface of the Rayleigh step extends parallel to the flat surface of the land, the invention is not limited to this configuration. For example, the bottom surface may be sloped to become shallower towards the closing surface.

[0096] Furthermore, in the above embodiments 1 to 8, even when the rotating sealing ring 20 rotates counterclockwise and a relative negative pressure is generated, the sealed fluid F flowing from the land to the occluded portion of the Rayleigh step 15 is less likely to accumulate contaminants in the occluded portion as it moves along the curved surface. Also, microscopically, the point at which the sealed fluid F has the lowest pressure in the occluded portion changes in the width direction over time in a plan view, and the occluded portions are smoothly connected, making it less likely for contaminants to accumulate. [Explanation of Symbols]

[0097] 1. Axis of rotation 2 sleeves 4 Housing 10. Stationary sealing ring (sliding part) 11 Sliding surface 12 Land 13. Dynamic pressure generation mechanism 14 Fluid introduction groove 15. Rayleigh step (dynamic pressure generating groove) 15A End part (occlusion part) 15a Bottom 15b,15c side 15d Terminal surface (occlusion surface) 15e,15f side edge 15g terminal edge (closed edge) 15h~15k curved surface 16. Dynamic pressure generating groove (spiral groove) 20 Rotating sealing ring (other sliding parts) 21 Sliding surface 130 Dynamic pressure generation mechanism 140 Fluid introduction groove 150 Dynamic pressure generating grooves 160 Dynamic pressure generating groove (spiral groove) 215 Rayleigh step (dynamic pressure generating groove) 215b,215c Side 215d Terminal surface (occlusion surface) 315 Rayleigh step (dynamic pressure generating groove) 315b,315c side 315d Terminal surface (occlusion surface) 415 Rayleigh step (dynamic pressure generating groove) 415b,415c Side 415d Terminal surface (occlusion surface) 515 Rayleigh step (dynamic pressure generating groove) 515b,515c side 515d Terminal surface (occlusion surface) A atmosphere F Sealed fluid R1~R5 Radius of curvature S1 Internal space (space on the side of the sealed fluid) S2 External space (space on the leakage side)

Claims

1. A sliding component positioned at a relative rotating part of a rotating machine, which slides relative to other sliding components, and whose sliding surface is provided with a fluid introduction groove that communicates with at least one of the spaces on the sealed fluid side or the leaking side, and a dynamic pressure generating groove that communicates with the fluid introduction groove and extends in the circumferential direction, The side edges and the closing edge of the aforementioned dynamic pressure generating groove are curved and continuous in a plan view. The dynamic pressure generating groove is a sliding component that rises from the bottom surface and has sides that extend in the depth direction from both side edges.

2. The sliding part according to claim 1, wherein the side surface extending in the depth direction from the side edge and the closing surface extending in the depth direction from the closing edge are curved and continuous.

3. The sliding part according to claim 2, wherein both of the aforementioned side surfaces and the closing surface are continuous by a curved surface having a radius of curvature in a plan view.

4. The sliding part according to claim 2, wherein the closing surface is a curved surface having a radius of curvature.

5. The sliding part according to any one of claims 2 to 4, wherein the bottom surface constituting the dynamic pressure generating groove and the closing surface are curved and continuous in cross-sectional view.

6. The sliding component according to claim 1, wherein the fluid introduction groove communicates with the space on the sealed fluid side, and the sliding surface is provided with a spiral groove that communicates with the space on the leakage side but does not communicate with the space on the sealed fluid side.

7. A sliding component that is positioned at a relative rotating part of a rotating machine and slides relative to another sliding component, wherein the sliding surface is provided with a fluid introduction groove that communicates with at least one of the spaces on the sealed fluid side or the leak side, and a dynamic pressure generating groove that communicates with the fluid introduction groove and extends in the circumferential direction, The side edges and the closing edge of the aforementioned dynamic pressure generating groove are curved and continuous in a plan view. Each of the curved closed portions of the aforementioned dynamic pressure generating grooves is a sliding component that overlaps in the circumferential direction with the fluid introduction groove which communicates with the dynamic pressure generating groove downstream in the relative rotation direction.

8. The sliding part according to claim 1 or 7, wherein the closing edge is formed in a semi-elliptical shape in plan view.

9. The side edges have a first side edge located on the leak side in a plan view and a second side edge located on the side of the fluid to be sealed, wherein the first side edge extends downstream in the relative rotational direction from the second side edge. The sliding part according to claim 1 or 7, wherein the closing edge is formed by an inclined straight line and a curve connecting the inclined straight line to the first side edge and the second side edge.

10. The sliding part according to claim 1 or 7, wherein the closing edge is formed by a pair of inclined straight lines facing each other in the radial direction and a curve connecting the pair of inclined straight lines.

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