Sliding component

Abstract

Provided is a sliding component that stably exhibits high lubricity between sliding surfaces.　A sealed fluid F including a lubricating fluid F2 and a working fluid F1 having a boiling point lower than that of the lubricating fluid F2 is sealed in a sealed fluid space S1, and a pumping groove 13 that extends in a circumferential direction and does not communicate with the sealed fluid space S1 is provided in a sliding surface 11 of at least one sliding ring 10.

Description

Sliding parts 【0001】 The present invention relates to sliding parts that rotate relative to each other, and is used, for example, for a pair of sliding parts used in a shaft seal device that seals the rotating shaft of a rotating machine in the field of automobiles, general industrial machines, or other sealing fields, or a pair of sliding parts used in a bearing of a machine in the field of automobiles, general industrial machines, or other bearing fields. 【0002】 As a sliding part for preventing leakage of the fluid to be sealed around the rotating shaft in a rotating machine, for example, a mechanical seal composed of a pair of annular sliding rings that rotate relative to each other and whose sliding surfaces slide against each other is known. In such a mechanical seal, in recent years, reduction of energy lost due to sliding has been desired for environmental protection and the like, and some sliding surfaces of the sliding rings are provided with hydrodynamic grooves. 【0003】 For example, on the sliding surface of one sliding ring of the mechanical seal shown in Patent Document 1, an annular groove extending in the circumferential direction and a conduction groove extending from the annular groove toward the inner diameter side and communicating the fluid space to be sealed and the annular groove are provided. When the pair of sliding rings rotate relative to each other, the fluid in the fluid space to be sealed flows into the annular groove through the conduction groove, improving the lubricity between the sliding surfaces. 【0004】 Japanese Patent No. 7551264 (page 5, Figure 2) 【0005】 In the mechanical seal as in Patent Document 1, the fluid in the fluid space to be sealed is in a state where lubricating oil as a lubricating fluid is mixed with refrigerant as a working fluid. However, since there is a variation in the ratio of lubricating oil in the fluid supplied between the sliding surfaces, the amount of lubricating oil becomes insufficient, and there is a risk that the lubricity cannot be stably improved. 【0006】 The present invention has been made by paying attention to such problems, and an object thereof is to provide a sliding part that can stably exhibit high lubricity between sliding surfaces. 【0007】To solve the aforementioned problems, the present invention provides a sliding component comprising a pair of sliding rings arranged at relative rotational positions and a pair of sliding surfaces that partition a sealed fluid space and a leakage space, wherein the sealed fluid space contains a sealed fluid including a lubricating fluid and a working fluid with a lower boiling point than the lubricating fluid, and the sliding surface of at least one of the sliding rings is provided with a pumping groove that extends in the circumferential direction and is not in communication with the sealed fluid space. With this, the working fluid with a lower boiling point in the sealed fluid that flows into the pumping groove is vaporized, the working fluid and the lubricating fluid are separated, and the separated lubricating fluid is supplied between the sliding surfaces, so that high lubricity between the sliding surfaces can be stably achieved. 【0008】 A circumferentially extending deep groove may be positioned on the sliding surface of one of the sliding rings, closer to the leakage space than the pumping groove. This allows the separated lubricating fluid to be stored in the deep groove on the leakage space side, thereby enabling stable and high lubricity between the sliding surfaces. 【0009】 The inner diameter side of the pair of sliding surfaces may constitute the sealed fluid space. This makes it easier to guide the lubricating fluid into the deep groove by centrifugal force. 【0010】 The deep groove may have a wide section, which may be positioned downstream of the downstream end of the pumping groove on the relative rotation side. This makes it easier to recover the lubricating fluid that has flowed out from the downstream end of the pumping groove on the relative rotation side into the deep groove via the wide section. 【0011】 The deep groove may be annular. This makes it easier to collect and retain the lubricating fluid that has flowed out between the sliding surfaces within the deep groove. 【0012】 A recovery groove communicating with the deep groove may be provided between the deep groove and the pumping groove. This allows the lubricating fluid that has flowed out from the pumping groove to the sliding surface to be recovered from the recovery groove into the deep groove. 【0013】 A positive pressure generating groove communicating with the deep groove may be provided. This allows positive pressure to be generated in the positive pressure generating groove using the sealed fluid in the deep groove, thereby improving lubrication. 【0014】The positive pressure generating groove may be positioned between the deep groove and the pumping groove. This arrangement makes it easier for the negative pressure generated in the pumping groove and the positive pressure generated in the positive pressure generating groove to balance radially, thereby suppressing excessive lifting or proximity between the sliding surfaces. 【0015】 This is a longitudinal cross-sectional view showing an example of a mechanical seal in Embodiment 1 of the present invention. This is a view of the sliding surface of the stationary sealing ring in Embodiment 1 as seen from the axial direction. This is an enlarged view of the main part of Figure 2. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 2 of the present invention as seen from the axial direction. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 3 of the present invention as seen from the axial direction. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 4 of the present invention as seen from the axial direction. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 5 of the present invention as seen from the axial direction. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 6 of the present invention as seen from the axial direction. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 7 of the present invention as seen from the axial direction. This is an enlarged view of a modified example of the stationary sealing ring in Embodiment 2 of the present invention. 【0016】 Embodiments for implementing the sliding component according to the present invention will be described below based on examples. 【0017】 The sliding component according to Embodiment 1 will be described with reference to Figures 1 to 3. In this embodiment, a mechanical seal will be used as an example of a sliding component. In this embodiment, the mechanical seal has an internal space S1 as the sealed fluid space in which a high-pressure sealed fluid F, for example, a mixture of a refrigerant as the working fluid and a lubricating oil as the lubricating fluid, is present, and the external space S2 as the leakage space is in communication with the low-pressure atmosphere A. Also, for the sake of explanation, dots may be added to grooves and the like formed on the sliding surface in the drawings. 【0018】 The mechanical seal shown in Figure 1 is an outside-type seal that seals the fluid being sealed, preventing leakage from the inner diameter side to the outer diameter side of the sliding surface. 【0019】The mechanical seal mainly consists of a stationary sealing ring 10 and a rotating sealing ring 20. The stationary sealing ring 10 is annular in shape and is provided on a seal cover 5 fixed to the housing 4 of the equipment to be mounted, in a non-rotatable state and movable in the axial direction. The rotating sealing ring 20 is annular in shape and is provided on a rotating shaft 1 via a sleeve 2 so as to be rotatable with the rotating shaft 1. 【0020】 The stationary sealing ring 10 is biased in the axial direction by the elastic member 7. 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 this flat surface does not have any grooves or other recesses. 【0021】 The stationary sealing ring 10 and the rotating sealing ring 20 are typically formed from two 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 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, sintered carbon, etc. In addition to the sliding materials mentioned above, metal materials, resin materials, surface modification materials (coating materials), composite materials, etc., are also applicable. 【0022】 As shown in Figures 2 and 3, the rotating sealing ring 20 slides relative to the stationary sealing ring 10 in a counterclockwise direction, as indicated by the solid arrows. In other words, the mechanical seal in this embodiment is of a unidirectional rotation type. 【0023】 The sliding surface 11 of the stationary sealing ring 10 is provided with a storage groove 12 as a deep groove, a negative pressure generating groove 13 as a pumping groove, a positive pressure generating groove 14, and an inverse spiral groove 15. 【0024】The storage groove 12 is composed of an annular groove portion 12A and multiple (four in this embodiment) widened bulges 12B. The annular groove portion 12A is provided approximately concentrically with the sliding surface 11 at approximately the radial center of the sliding surface 11. The storage groove 12 is not limited to an annular shape; for example, multiple grooves may be provided in the circumferential direction, or it may be C-shaped in an axial view, and preferably it should be provided in a range of 90% or more of the circumferential length of the sliding surface 11. 【0025】 The bulge 12B protrudes inward from the annular groove 12A. This bulge 12B has the same depth as the annular groove 12A and is roughly trapezoidal in axial view. The shape and number of bulges 12B can be freely changed. Furthermore, the bulge 12B may have a different depth than the annular groove 12A, and its bottom surface may be inclined. 【0026】 Multiple negative pressure generating grooves 13 (four in this embodiment) are provided on the sliding surface 11 on the inner diameter side of the storage groove 12. The negative pressure generating grooves 13 extend circumferentially in a substantially concentric manner with the sliding surface 11 and have an arc shape. 【0027】 The negative pressure generating groove 13 is shallower than the storage groove 12. For example, the negative pressure generating groove 13 is about 1 / 20th the depth of the storage groove 12. Furthermore, the negative pressure generating groove 13 is not limited to having a constant depth in the circumferential direction; for example, it may gradually deepen toward the downstream side of relative rotation. 【0028】 The upstream end 13a of the negative pressure generating groove 13, which is on the relative rotation side, is positioned on the inner diameter side of the bulge 12B of the storage groove 12. The downstream end 13b of the negative pressure generating groove 13, which is on the relative rotation side, is positioned on the inner diameter side, close to the upstream side of the bulge 12B of the adjacent storage groove 12. 【0029】 The negative pressure generating groove 13 has a cavitation generating section 13A in the region upstream of relative rotation including the end 13a, and a lubrication fluid guiding section 13B in the region downstream of relative rotation including the end 13b. 【0030】 Multiple positive pressure generating grooves 14 are provided on the sliding surface 11 on the inner diameter side of the annular groove portion 12A (four in this embodiment). 【0031】The positive pressure generating groove 14 extends circumferentially from the bulging portion 12B of the storage groove 12 toward the downstream side of relative rotation. The positive pressure generating groove 14 and the negative pressure generating groove 13 are arranged to overlap radially and are separated by a land 16. In other words, the positive pressure generating groove 14 is located between the storage groove 12 and the negative pressure generating groove 13. 【0032】 The positive pressure generating groove 14 is shorter than the negative pressure generating groove 13. Alternatively, the positive pressure generating groove 14 may be the same length as the negative pressure generating groove 13, or longer than the negative pressure generating groove 13. 【0033】 The positive pressure generating groove 14 has approximately the same depth as the negative pressure generating groove 13. However, the positive pressure generating groove 14 may have a different depth than the negative pressure generating groove 13. Furthermore, the positive pressure generating groove 14 is not limited to having a constant depth in the circumferential direction; for example, it may gradually become shallower toward the downstream side of relative rotation. 【0034】 Multiple reverse spiral grooves 15 are provided on the sliding surface 11 on the outer diameter side of the annular groove portion 12A. 【0035】 The reverse spiral groove 15 extends linearly from the annular groove portion 12A toward the outer diameter and toward the downstream side of relative rotation. The reverse spiral groove 15 may also extend in a curved manner. 【0036】 Furthermore, the inverse spiral groove 15 has approximately the same depth as the negative pressure generating groove 13. However, the inverse spiral groove 15 may have a different depth than the negative pressure generating groove 13. Also, the inverse spiral groove 15 is not limited to having a constant depth in the direction of extension, but may gradually deepen toward the downstream side of relative rotation. 【0037】 Next, we will describe the state in which the rotating sealing ring 20 is rotated relative to the stationary sealing ring 10. 【0038】 As shown in Figure 3, when the rotating sealing ring 20 rotates relative to the stationary sealing ring 10, the fluid moves within each groove in the direction of rotation of the stationary sealing ring 10. 【0039】More specifically, the fluid in the storage groove 12 moves to the positive pressure generating groove 14, and positive pressure is generated at the end 14a of the positive pressure generating groove 14 and its vicinity. As a result, the sliding surfaces 11 and 21 are separated, more of the sealed fluid F is introduced from the internal space S1, and the sliding performance is improved. 【0040】 Furthermore, the fluid in the negative pressure generating groove 13 moves to the downstream side of the relative rotation, and a relative negative pressure is generated near the upstream end 13a of the negative pressure generating groove 13, i.e., the cavitation generating section 13A. As a result, the sealed fluid F around the cavitation generating section 13A is collected into the negative pressure generating groove 13. 【0041】 As mentioned above, the sealed fluid F is a liquid mixture of refrigerant F1 as the working fluid and lubricating oil F2 as the lubricating fluid. Refrigerant F1 has a much lower boiling point than lubricating oil F2. Therefore, when the sealed fluid F is collected in the negative pressure generating groove 13, the refrigerant F1 is actively vaporized by the negative pressure of the cavitation generating section 13A, and the refrigerant F1 and lubricating oil F2 are separated. 【0042】 The separated gaseous refrigerant F1 and liquid lubricating oil F2 flow out between the sliding surfaces 11 and 21 from around the lubricating fluid guide section 13B due to a relative positive pressure generated near the downstream end 13b of the negative pressure generating groove 13, i.e., the lubricating fluid guide section 13B. In other words, the refrigerant F1 and lubricating oil F2 are guided to the downstream side of the relative rotation by the lubricating fluid guide section 13B. 【0043】 The lubricating oil F2 that flows between the sliding surfaces 11 and 21 has a higher viscosity and density than the refrigerant F1, and therefore moves more easily in the outer diameter direction than the refrigerant F1 due to the relative rotational force and centrifugal force acting on the lubricating oil F2. As a result, the lubricating oil F2 that flows between the sliding surfaces 11 and 21 is recovered in the storage groove 12. The refrigerant F1 has a lower viscosity and density, and therefore tends to stay on the inner diameter side compared to the lubricating oil F2. It is less likely to flow into the storage groove 12, which is filled with the sealed fluid F or lubricating oil F2, and even if it does flow into the storage groove 12, it is less likely to remain there. 【0044】The fluid in the reverse spiral groove 15 moves to the relatively rotating downstream side, and a relative negative pressure occurs at the outer diameter side end 15a of the reverse spiral groove 15 and its vicinity, and the fluid around the end 15a is collected into the reverse spiral groove 15. Since the fluid in the reverse spiral groove 15 flows toward the storage groove 12, it acts to push back the sealed fluid F in the storage groove 12 and the sealed fluid F that tries to move to the outer diameter side beyond the storage groove 12 toward the inner diameter side, and it is possible to prevent the sealed fluid F from leaking into the outer space S2. 【0045】 As described above, the refrigerant F1 with a low boiling point in the sealed fluid F flowing in through the negative pressure generating groove 13 is vaporized, so that the refrigerant F1 and the lubricating oil F2 can be separated, and it is easy to store the lubricating oil F2 with a high concentration in the storage groove 12. Therefore, the lubricity between the sliding surfaces 11 and 21 can be stably exhibited. 【0046】 Also, the refrigerant F1 in the sealed fluid F can be vaporized in the cavitation generating portion 13A of the negative pressure generating groove 13, and the lubricating oil F2 separated downstream can be induced in the lubricating fluid guiding portion 13B. 【0047】 Further, since the bulging portion 12B of the adjacent storage groove 12 is arranged close to the downstream side of the end 13b on the relatively rotating downstream side of the negative pressure generating groove 13, the lubricating oil F2 discharged from the end 13b between the sliding surfaces 11 and 21 is easily collected into the storage groove 12. Since the bulging portion 12B and the end 13b of the negative pressure generating groove 13 slightly overlap in the radial direction, the lubricating oil F2 discharged from the end 13b between the sliding surfaces 11 and 21 is particularly easily collected into the storage groove 12. 【0048】 Also, since the sealed fluid F is enclosed in the inner space S1 of the sliding surfaces 11 and 21, that is, it is an outside type mechanical seal, a centrifugal force acts on the lubricating oil F2 with a large density separated from the refrigerant F1, and the lubricating oil F2 is easily collected into the storage groove 12 on the outer diameter side. 【0049】 Further, the negative pressure generating groove 13 is not connected to the inner space S1. That is, since the periphery of the negative pressure generating groove 13 is surrounded by the land 16, the separated lubricating oil F2 is not easily returned to the inner space S1 and is discharged between the sliding surfaces 11 and 21, so it is easily guided to the storage groove 12. 【0050】Furthermore, because the storage groove 12 is annular, the lubricating oil F2 that flows between the sliding surfaces 11 and 21 can be reliably collected and retained in the storage groove 12 at any position in the circumferential direction. Also, because the storage groove 12 is deep, the collected lubricating oil F2 tends to remain in the storage groove 12. 【0051】 Furthermore, since a circumferentially continuous land 16 is arranged between the negative pressure generating groove 13 and the bulging portion 12B of the storage groove 12, the separated lubricating oil F2 is recovered into the storage groove 12 via the land 16. 【0052】 Furthermore, a positive pressure generating groove 14 is provided that communicates with the storage groove 12, and positive pressure can be generated at the end 14a of the positive pressure generating groove 14 using the lubricating oil F2 in the storage groove 12, thereby improving lubrication. 【0053】 Furthermore, since the positive pressure generating groove 14 and the negative pressure generating groove 13 are close together in the radial direction, the lubricating oil F2 that flows out from the positive pressure generating groove 14 between the sliding surfaces 11 and 21 is immediately recovered into the negative pressure generating groove 13. 【0054】 Furthermore, the negative pressure generating groove 13 and the positive pressure generating groove 14 overlap radially via the land 16. This arrangement makes it easier for the negative pressure generated in the negative pressure generating groove 13 and the positive pressure generated in the positive pressure generating groove 14 to balance radially, thereby suppressing excessive lifting or proximity between the sliding surfaces 11 and 21. 【0055】 Furthermore, the positive pressure generating groove 14 extends circumferentially from the bulging portion 12B of the storage groove 12. This makes it easier to smoothly supply lubricating oil F2 from the bulging portion 12B to the positive pressure generating groove 14. In addition, the sides 12Ba, 12Ba of the bulging portion 12B are inclined to taper toward the inner diameter, allowing lubricating oil F2 to flow smoothly between the annular groove portion 12A of the storage groove 12 and the bulging portion 12B. 【0056】 Furthermore, the side surfaces 12Ba, 12Ba of the bulging portion 12B are not limited to being inclined to taper toward the inner diameter side, but may also be inclined to expand toward the inner diameter side, or they may be inclined in the circumferential direction and extend parallel to each other. In addition, the side surfaces 12Ba, 12Ba may extend parallel to the radial direction. 【0057】Furthermore, the end 14a of the positive pressure generating groove 14 and the ends 13a and 13b of the negative pressure generating groove 13 are offset in the circumferential direction. This arrangement ensures that the negative pressure generated at end 13a of the negative pressure generating groove 13 and the positive pressure generated at end 13b are less affected by the positive pressure generated at end 14a of the positive pressure generating groove 14. 【0058】 Next, the sliding parts according to Embodiment 2 will be described with reference to Figure 4. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted. 【0059】 As shown in Figure 4, the rotating sealing ring 20 of this embodiment 2 slides relative to the stationary sealing ring 210 mainly in a counterclockwise direction as indicated by the solid arrows. The direction of rotation may also be switched to a clockwise direction as indicated by the dashed arrows. Hereafter, the direction of the solid arrows will be described as the forward rotation direction, and the direction of the dashed arrows will be described as the reverse rotation direction. When describing the shape of each groove, the forward rotation direction will be used as the reference. Furthermore, the flow of lubricating oil F2 during forward rotation is illustrated by the solid arrows, and the flow of lubricating oil F2 during reverse rotation is illustrated by the dashed arrows. 【0060】 The sliding surface 211 of the stationary sealing ring 210 is provided with a storage groove 212, a negative pressure generating groove 213, a positive pressure generating groove 214, a recovery groove 217, and a reverse spiral groove 215. The storage groove 212, positive pressure generating groove 214, and reverse spiral groove 215 have the same configuration as in Embodiment 1. 【0061】 Multiple negative pressure generating grooves 213 are provided on the sliding surface 211 on the inner diameter side of the storage groove 212. These negative pressure generating grooves 213 comprise first portions 213a, 213b, second portions 213c, 213d, and third portion 213e. 【0062】More specifically, the first parts 213a and 213b are located on the innermost diameter side of the negative pressure generating groove 213. The second part 213c extends from the downstream end of the relative rotation of the first part 213a, inclined toward the outer diameter side toward the downstream side of relative rotation. The second part 213d extends from the upstream end of the relative rotation of the first part 213b, inclined toward the outer diameter side toward the upstream side of relative rotation. The third part 213e extends in an arc shape in the circumferential direction and connects the outer diameter ends of the second parts 213c and 213d. In other words, the negative pressure generating groove 213 has a crank shape at both circumferential ends and is approximately Ω-shaped in axial view. 【0063】 Furthermore, the closed ends 213f and 213g of the first sections 213a and 213b have a shape in which the outer diameter side tapers towards the circumferential direction. The closed ends 213f and 213g are located on the inner diameter side of adjacent bulging sections 212B and 212B in the storage groove 212, respectively. 【0064】 The negative pressure generating groove 213 has a symmetrical shape with respect to a virtual line α that extends radially and passes through the circumferential center. However, the negative pressure generating groove 213 may also have an asymmetrical shape. 【0065】 The recovery groove 217 extends circumferentially from the bulging portion 212B of the storage groove 212 toward the upstream side of relative rotation. The recovery groove 217 is positioned to overlap the positive pressure generation groove 214 in the circumferential direction. Although the recovery groove 217 has substantially the same shape as the positive pressure generation groove 214, its depth, length, outer shape, number, etc., may differ. 【0066】 When the rotating sealing ring 20 rotates in the forward direction, negative pressure is generated in the region on the first portion 213a side of the negative pressure generating groove 213, separating the refrigerant F1 and the lubricating oil F2. The separated lubricating oil F2 is guided from the region on the first portion 213a side of the negative pressure generating groove 213 to the downstream side of the relative rotation. In other words, when the rotating sealing ring 20 rotates in the forward direction, the region on the first portion 213a side of the negative pressure generating groove 213 becomes a cavitation generation area, and the region on the first portion 213b side becomes a lubricating fluid guidance area. 【0067】Furthermore, since the closed end 213g on the downstream side of the relative rotation during forward rotation tapers towards the circumferential direction on its outer diameter side, the separated lubricating oil F2 is smoothly guided toward the bulging portion 212B of the storage groove 212. Any lubricating oil F2 that is not collected in the bulging portion 212B of the storage groove 212 is collected in the negative pressure generating groove 213 on the downstream side of the relative rotation. 【0068】 Furthermore, when the rotating sealing ring 20 rotates in the forward direction, positive pressure is generated at the end 214a of the positive pressure generating groove 214, and relative negative pressure is generated at the end 217a of the recovery groove 217. As a result, lubricating oil F2 that flows out from the end 214a of the positive pressure generating groove 214 between the sliding surfaces can be recovered in the negative pressure generating groove 213 and the recovery groove 217. In addition, lubricating oil F2 that flows out to the outer diameter side from the third portion 213e of the negative pressure generating groove 213 can be recovered from the recovery groove 217 into the storage groove 212. 【0069】 On the other hand, when the rotating sealing ring 20 rotates in the reverse direction, the region on the first portion 213b side of the negative pressure generating groove 213 becomes a cavitation generating portion, and the region on the first portion 213a side becomes a lubrication fluid guidance portion. Since the closed end 213f on the downstream side of the relative rotation during reverse rotation tapers toward the outer diameter, the separated lubricating oil F2 is smoothly guided toward the bulging portion 212B of the storage groove 212. 【0070】 Furthermore, when the rotating sealing ring 20 rotates in the reverse direction, positive pressure is generated at the end 217a of the recovery groove 217, and relative negative pressure is generated at the end 214a of the positive pressure generating groove 214. As a result, lubricating oil F2 that has flowed out from the end 217a of the recovery groove 217 between the sliding surfaces can be recovered in the negative pressure generating groove 213 and the positive pressure generating groove 214. In addition, lubricating oil F2 that has flowed out to the outer diameter side from the third portion 213e of the negative pressure generating groove 213 can be recovered from the positive pressure generating groove 214 into the storage groove 212. 【0071】 In other words, during reverse rotation, the recovery groove 217 functions as a positive pressure generating groove, and the positive pressure generating groove 214 functions as a recovery groove. 【0072】 Furthermore, since the rotational speed of the rotating sealing ring 20 when it rotates in the reverse direction is low, the lubricating oil F2 hardly leaks from the storage groove 212 through the reverse spiral groove 215 to the outside space S2. 【0073】In this embodiment 2, a configuration in which the rotating sealing ring 20 is designed for both rotations is illustrated. However, for example, as shown in Figure 10, a stationary sealing ring 210 with negative pressure generating grooves 213 for both rotations on the sliding surface 211 may also be used, i.e., the stationary sealing ring 210 of embodiment 2. 【0074】 Next, the sliding parts according to Embodiment 3 will be described with reference to Figure 5. Note that descriptions of components that are identical to those in Embodiment 2 and therefore redundant will be omitted. 【0075】 As shown in Figure 5, the storage groove 312 in the sliding surface 311 of the stationary sealing ring 310 of this embodiment 3 has a communication groove portion 318 that connects the annular groove portion 312A and the third portion 313e in the circumferential center of the negative pressure generating groove 313. The communication groove portion 318 is formed to the same depth as the storage groove 312. 【0076】 According to this, a portion of the lubricating oil F2 separated at the cavitation generation section 313A on the relative rotation upstream side of the negative pressure generation groove 313 can be recovered into the storage groove 312 from the communication groove section 318. In addition, any excess lubricating oil F2 in the storage groove 312 can be discharged from the communication groove section 318 towards the lubricating fluid guide section 313B on the relative rotation downstream side of the negative pressure generation groove 313. 【0077】 Furthermore, since the side walls 318a, 318a of the communication groove 318 are inclined to taper toward the inner diameter, the lubricating oil F2 flows smoothly between the annular groove 312A of the storage groove 312 and the negative pressure generating groove 313. 【0078】 Furthermore, the connecting groove 318 may have a different depth from the storage groove 312. Its bottom surface may also be inclined. 【0079】 Furthermore, the side walls 318a, 318a of the communication groove 318 are not limited to being inclined to taper toward the inner diameter side, but may also be inclined to widen toward the inner diameter side, or may be inclined in the circumferential direction and extend parallel to each other. In addition, the side walls 318a, 318a may extend parallel to each other in the radial direction. 【0080】 Next, the sliding parts according to Embodiment 4 will be described with reference to Figure 6. Note that the description of components that are identical to those in Embodiment 2 and therefore redundant will be omitted. Furthermore, only the state during forward rotation will be described here. 【0081】 As shown in Figure 6, in the sliding surface 411 of the stationary sealing ring 410 of this embodiment 4, the third portion 413e of the negative pressure generating groove 413 is positioned on the inner diameter side of the bulging portion 412B of the storage groove 412. 【0082】 According to this, the flow of lubricating oil F2 from the recovery groove 417 through the bulging portion 412B to the positive pressure generating groove 414 allows the lubricating oil F2 that leaks out to the outer diameter side from the third portion 413e of the negative pressure generating groove 413 to be recovered in the storage groove 412. 【0083】 Next, the sliding parts according to Embodiment 5 will be described with reference to Figure 7. Note that descriptions of components that are identical to those in Embodiment 2 and therefore redundant will be omitted. 【0084】 As shown in Figure 7, in the sliding surface 511 of the stationary sealing ring 510 of this embodiment 5, a land 516 is provided that is continuous in the circumferential direction between the reverse spiral groove 515 and the storage groove 512. In other words, the reverse spiral groove 515 and the storage groove 512 are not in communication. 【0085】 According to this, during forward rotation, similar to Embodiment 1, the fluid in the reverse spiral groove 515 flows toward the storage groove 12, thereby pushing the lubricating oil F2 toward the inner diameter side, and during reverse rotation, it is possible to prevent the lubricating oil F2 in the storage groove 512 from leaking from the reverse spiral groove 515 into the outer space S2. 【0086】 Furthermore, some of the multiple inverted spiral grooves 515 may be connected to the storage groove 512. 【0087】 Next, the sliding parts according to Embodiment 6 will be described with reference to Figure 8. Note that descriptions of components that are identical to those in Embodiment 5 and therefore redundant will be omitted. 【0088】 As shown in Figure 8, the sliding surface 611 of the stationary sealing ring 610 in this embodiment 6 is provided with multiple pumping grooves 615 instead of the reverse spiral groove 515 of embodiment 5. Note that only one pumping groove 615 is shown in Figure 8. 【0089】The pumping groove 615 has a shape similar to that of the negative pressure generating groove 613, that is, it has an approximately Ω shape in axial view with both circumferential ends forming a crank shape. The circumferential central portion 615a of the pumping groove 615 is in communication with the outer space S2 along the circumferential direction. 【0090】 During forward rotation, fluid is collected near the end 615b of the pumping groove 615 and discharged from the end 615c. During reverse rotation, fluid is collected near the end 615c of the pumping groove 615 and discharged from the end 615b. 【0091】 The ends 615b and 615c of the pumping groove 615 have a shape that tapers towards the circumferential direction on the inner diameter side. Therefore, the fluid discharged from the ends 615b and 615c of the pumping groove 615 is guided toward the inner diameter side, and functions to push back the lubricating oil F2 that would otherwise leak out to the outer diameter side beyond the storage groove 612 toward the inner diameter side. 【0092】 Thus, the mechanism for pushing back lubricating oil that is about to leak out to the outer diameter side beyond the storage groove can be freely modified, not limited to a reverse spiral groove. 【0093】 Next, the sliding parts according to Embodiment 7 will be described with reference to Figure 9. Note that descriptions of components that are identical to those in Embodiment 2 and therefore redundant will be omitted. 【0094】 As shown in Figure 9, the mechanical seal of this embodiment 7 is an inside-type mechanical seal in which the fluid to be sealed F is enclosed in the outer space S2 and the inner space S1 is in communication with the atmosphere A. 【0095】 On the sliding surface 711 of the stationary sealing ring 710, a bulge 712B, a negative pressure generating groove 713, a positive pressure generating groove 714, and a recovery groove 717 are arranged on the outer diameter side of the storage groove 712, and an inverse spiral groove 715 is arranged on the inner diameter side of the storage groove 712. 【0096】 In this case, it is preferable to provide a mechanism that guides the lubricating oil F2 separated in the negative pressure generating groove 713 toward the storage groove 712 on the inner diameter side. For example, a guide wall can be provided on the mating sliding surface that extends inclined toward the upstream side of relative rotation from the outer diameter side toward the inner diameter side. 【0097】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. 【0098】 For example, in Examples 1 to 7 above, the sealed fluid was exemplified as a liquid mixture of a refrigerant and a lubricating oil, but the sealed fluid may contain two or more types of working fluids and lubricating fluids with different boiling points. Alternatively, the working fluid may be partially vaporized beforehand, and the lubricating fluid may be mixed in a mist form. 【0099】 Furthermore, in the above embodiments 1 to 7, the negative pressure generating groove had a shape that extended in the circumferential direction, but the shape can be freely changed as long as it has a cavitation generating section and a lubrication fluid guidance section. 【0100】 Furthermore, while embodiments 1 to 7 above illustrate a configuration in which the deep groove has a wide portion, the groove width may be constant. Also, the deep groove is not limited to annular shape, but may have a component extending in the circumferential direction. For example, it may have a polygonal shape or a sinusoidal shape in the circumferential direction when viewed in the axial direction. 【0101】 Furthermore, while embodiments 1 to 7 above illustrate configurations in which the positive pressure generation groove and recovery groove extend from the wide portion of the deep groove, the positive pressure generation groove and recovery groove may extend from a portion other than the wide portion of the deep groove. Also, the positive pressure generation groove and recovery groove are not limited to extending in the circumferential direction; for example, they may be Rayleigh steps or inverted Rayleigh steps extending in a substantially L-shape from the deep groove, or spiral grooves or inverted spiral grooves extending at an angle from the deep groove. 【0102】 Furthermore, although embodiments 1 to 7 above illustrate configurations in which the positive pressure generation groove and the recovery groove communicate with the deep groove, they may not communicate with each other. 【0103】 Furthermore, while mechanical seals were used as an example of sliding parts in Examples 1 to 7 above, other mechanical seals such as those used in general industrial machinery, automobiles, and water pumps may also be used. Moreover, the invention is not limited to mechanical seals, but may also use sliding parts other than mechanical seals, such as sliding bearings. 【0104】Furthermore, in the above-described embodiments 1 to 7, 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. 【0105】 Furthermore, while embodiments 1 to 7 illustrate configurations in which the deep groove and negative pressure generating groove are provided on the sliding surface of a stationary sealing ring, they may also be provided on the sliding surface of a rotating sealing ring. 【0106】 1 Rotating shaft 4 Housing 10 Stationary sealing ring (one sliding ring) 11 Sliding surface 12 Storage groove (deep groove) 12A Annular groove 12B Bulging section (wide section) 13 Negative pressure generating groove (pumping groove) 13A Cavitation generating section 13B Lubrication fluid guide section 14 Positive pressure generating groove 15 Reverse spiral groove 16 Land 20 Rotating sealing ring 21 Sliding surface 217 Recovery groove 217a End A Atmosphere F Sealed fluid F1 Refrigerant (working fluid) F2 Lubricating oil (lubricating fluid) S1 Inner space (sealed fluid space) S2 Outer space (leakage space)

Claims

1. A sliding component comprising a pair of sliding rings positioned relative to each other at their rotational positions, and a pair of sliding surfaces that separate a sealed fluid space from a leak space, wherein the sealed fluid space contains a sealed fluid including a lubricating fluid and a working fluid with a lower boiling point than the lubricating fluid, and the sliding surface of at least one of the sliding rings comprises a pumping groove that extends circumferentially and does not communicate with the sealed fluid space.

2. The sliding component according to claim 1, wherein a circumferentially extending deep groove is located on the sliding surface of one of the sliding rings, on the side of the pumping groove that is closer to the leakage space.

3. The sliding component according to claim 2, wherein the inner diameter side of the pair of sliding surfaces is the sealed fluid space.

4. The sliding component according to claim 2, wherein the deep groove has a wide portion, and the wide portion is located downstream of the end of the pumping groove on the relative rotation downstream side.

5. The sliding part according to any one of claims 2 to 4, wherein the deep groove is annular.

6. The sliding component according to claim 2, wherein a recovery groove communicating with the deep groove is provided between the deep groove and the pumping groove.

7. The sliding component according to claim 2, wherein a positive pressure generating groove communicating with the deep groove is provided.

8. The sliding component according to claim 7, wherein the positive pressure generating groove is located between the deep groove and the pumping groove.

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