Mechanical seal

Abstract

Provided are sliding components capable of reducing leakage of a sealed fluid and arranging sliding surfaces to be spaced apart from each other in a balanced manner.　On at least one sliding surface 11 of a pair of sealing rings 10, 20, a supply hole 10b for supplying a barrier fluid G to between the sliding surfaces 11, 21 is formed. On the sliding surface 21, an introducing groove 23 which overlaps the supply hole 10b in an axial direction and extends in a circumferential direction is formed, and branch grooves 24, 25 extend from the introducing groove 23. The branch groove 25 extending to a leakage side S2 has a smaller groove volumetric capacity than the branch groove 24 extending to a sealed fluid side S1.

Description

[Technical Field]

[0001] The present invention relates to a sliding component that rotates relative to one another, and more particularly to a mechanical seal used in a shaft sealing device that seals the rotating shaft of a rotary machine in, for example, an automobile, general industrial machinery, or other sealing fields. [Background technology]

[0002] Mechanical seals, for example, are shaft sealing devices that prevent leakage of sealed fluids and are equipped with a pair of annular sliding components that rotate relative to one another and have sliding surfaces that slide against each other. In recent years, there has been a demand for reducing the energy lost due to sliding in such mechanical seals, for environmental reasons.

[0003] For example, in the mechanical seal shown in Patent Document 1, a fluid supply passage is formed in the stationary seal ring, connecting the seal surface with an external fluid supply source. The rotary seal ring is also provided with a fluid guide groove extending in the circumferential direction into which a gas such as nitrogen gas is introduced from the fluid supply passage, a plurality of dynamic pressure generating grooves extending from the fluid guide groove to the high pressure side, and a plurality of dynamic pressure generating grooves extending from the fluid guide groove to the low pressure side.

[0004] When gas is supplied from the fluid supply source, the gas flows into the fluid guide groove and is uniformly distributed as static pressure in the circumferential and radial directions between the relative sliding surfaces by the dynamic pressure generating grooves on the high-pressure and low-pressure sides, and this static pressure can separate the sliding surfaces. Furthermore, during relative rotation, dynamic pressure is generated in the dynamic pressure generating grooves in addition to the static pressure, so the sliding surfaces can be further separated from each other, effectively reducing friction that occurs during relative rotation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-022834 A (page 6, Figure 3) Summary of the Invention [Problem to be solved by the invention]

[0006] In a mechanical seal such as that disclosed in Patent Document 1, the dynamic pressure generating grooves on the high-pressure and low-pressure sides generate static and dynamic pressures approximately uniformly in the circumferential and radial directions between the opposing sliding surfaces, thereby separating the sliding surfaces in a balanced manner, but the configuration makes it easy for gas to leak from the dynamic pressure generating groove on the low-pressure side to the low-pressure side, which raises the risk of gas leaking from the dynamic pressure generating groove on the low-pressure side between the sliding surfaces and the sealed fluid on the high-pressure side leaking into the space on the low-pressure side.

[0007] The present invention has been made in view of these problems, and has as its object to provide a sliding component which reduces leakage of sealed fluid and can separate sliding surfaces in a balanced manner. [Means for solving the problem]

[0008] In order to solve the above problems, the mechanical seal of the present invention comprises: A mechanical seal is disposed between a housing and a rotary shaft that rotates relative to the housing, wherein a stationary seal ring fixed to the housing and a rotary seal ring fixed to the rotary shaft rotate relative to each other, separating a sealed fluid space from a leakage space, a supply hole for supplying barrier fluid between the sliding surfaces is formed in at least one of the sliding surfaces of the pair of seal rings, and an introduction groove is formed in the sliding surface of at least one of the pair of seal rings, the introduction groove overlapping with the supply hole in the axial direction and extending in a circumferential direction, branch grooves extending from the introduction groove to the sealed fluid side and the leakage side, respectively; The branch groove extending toward the leakage side has a groove volume smaller than that of the branch groove extending toward the sealed fluid side. With this, a sufficient amount of barrier fluid is supplied to the branch groove extending toward the sealed fluid side, and a small amount of barrier fluid is supplied to the branch groove extending toward the leakage side, thereby reducing leakage of the sealed fluid and enabling the sliding surfaces to be spaced apart in a balanced manner.

[0009] The branch groove extending toward the leakage side may have an average depth shallower than the branch groove extending toward the sealed fluid side. This ensures a wide opening area for the branch groove facing the mating seal ring, making it easy to separate the sliding surfaces from each other.

[0010] A radial end of the branch groove extending toward the leakage side may be located at a position radially farther from the introduction groove than a radial end of the branch groove extending toward the sealed fluid side. This allows pressure to be generated over a wide range in the radial direction of the leakage side.

[0011] The branch groove extending toward the leakage side and the branch groove extending toward the sealed fluid side may communicate with the introduction groove. This allows the barrier fluid to be reliably introduced from the introduction groove into both branch grooves, thereby separating the sliding surfaces from each other.

[0012] The introduction groove may be an endless ring. This allows pressure to be generated in a well-balanced manner in the circumferential direction, enabling the sliding surfaces to be stably separated from each other. Furthermore, during rotation, dynamic pressure is less likely to be generated locally in the circumferential direction of the introduction groove.

[0013] The branch groove may have a dynamic pressure generating portion extending in the direction of relative rotation of the pair of seal rings. This increases the lift force between the sliding surfaces due to the dynamic pressure generated during relative rotation in addition to the static pressure of the barrier fluid.

[0014] An end of the dynamic pressure generating portion in the branch groove extending to the leakage side may extend toward the introduction groove side. This can reduce leakage of the sealed fluid into the space on the leakage side together with the barrier fluid leaking from the end of the dynamic pressure generating portion in the branch groove extending to the leakage side.

[0015] The radial width of the branch groove extending toward the leakage side between the end of the dynamic pressure generating portion and the leakage side may be larger than the radial width between the end of the dynamic pressure generating portion and the introduction groove. This can further reduce leakage of the sealed fluid into the space on the leakage side together with the barrier fluid leaking from the tip of the branch groove extending on the leakage side. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing an example of a mechanical seal according to a first embodiment of the present invention. [Figure 2] 3 is a view of the sliding surface of the rotary seal ring in the first embodiment as viewed from the axial direction. FIG. [Figure 3] FIG. 3 is a partially enlarged view of FIG. 2. [Figure 4] AA cross-sectional view. [Figure 5] (a) is a BB cross-sectional view, and (b) is a CC cross-sectional view. [Figure 6] FIG. 2(a) is a schematic diagram showing the state of static pressure acting on a sliding surface, and FIG. 2(b) is a schematic diagram showing the state of dynamic pressure acting on a sliding surface. [Figure 7] FIG. 10 is a view of an introduction groove and branch grooves in a second embodiment according to the present invention, as viewed from the axial direction. [Figure 8] FIG. 10 is a view of an introduction groove and branch grooves in a third embodiment according to the present invention, as viewed from the axial direction. [Figure 9] FIG. 10 is a view of an introduction groove and branch grooves in a fourth embodiment according to the present invention, as viewed from the axial direction. [Figure 10] FIG. 10 is a view of an introduction groove and branch grooves in a fifth embodiment according to the present invention, as viewed from the axial direction. [Figure 11] FIG. 13 is a view of an introduction groove and branch grooves in a sixth embodiment according to the present invention, as viewed from the axial direction. [Figure 12] FIG. 13 is a view of an introduction groove and branch grooves in a seventh embodiment of the present invention, as viewed from the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mechanical seal according to the present invention will be described below with reference to the following examples. [Example]

[0018] A mechanical seal according to a first embodiment will be described with reference to FIGS. 1 to 6. FIG.

[0019] The mechanical seal shown in FIG. 1 is an inside type that seals against a sealed fluid F that attempts to leak from the outer diameter side to the inner diameter side of the sliding surface.

[0020] Specifically, the sealed fluid F exists in the outer space S1 of the mechanical seal, and the atmosphere A exists in the inner space S2. In this embodiment, the outer diameter side of the sliding components constituting the mechanical seal will be described as the sealed fluid space side (high pressure side), and the inner diameter side will be described as the leakage space side (low pressure side). For ease of explanation, grooves formed on the sliding surfaces may be marked with dots in the drawings.

[0021] The mechanical seal is mainly composed of a stationary seal ring 10 as the other annular seal ring, and a rotary seal ring 20 as one annular seal ring. The rotary seal ring 20 is mounted on the rotary shaft 1 via a sleeve 2 so as to be rotatable together with the rotary shaft 1. The stationary seal ring 10 is mounted on the inner diameter side of the housing 4 of the device to which it is attached so as to be non-rotating and movable in the axial direction.

[0022] Two O-rings 5 ​​are arranged axially spaced apart between the housing 4 and the stationary seal ring 10. A through-hole 4a is formed in the housing 4, penetrating it in the radial direction. The inner diameter opening of the through-hole 4a communicates with a space 6 partitioned by the housing 4, the stationary seal ring 10, and the two O-rings 5, and the outer diameter opening of the through-hole 4a communicates with a static pressure gas supply source 9 arranged externally. In addition, a cover 8 is fixed to the housing 4, and is arranged on the opposite side of the stationary seal ring 10 from the rotary seal ring 20.

[0023] An elastic member 7 is disposed between the cover 8 and the stationary seal ring 10. The stationary seal ring 10 is biased in the axial direction by the elastic member 7, so that the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 slide closely against each other.

[0024] Additionally, the stationary seal ring 10 is formed with a plurality of passages 10a in the circumferential direction, extending from the outer peripheral surface to the sliding surface 11. The opening on one end of the passages 10a communicates with the space 6, and the opening on the other end, a supply hole 10b, communicates with an introduction groove 23 (described later) of the rotary seal ring 20. The sliding surface 11 of the stationary seal ring 10 is configured as a flat surface except for the supply holes 10b.

[0025] The stationary seal ring 10 and the rotating seal ring 20 are typically formed from a combination of SiC (hard material) or SiC (hard material) and carbon (soft material), but this is not limited thereto; any sliding material used for mechanical seals can be used. Examples of SiC include sintered bodies using boron, aluminum, carbon, or other sintering aids, as well as materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC consisting of SiC and Si, SiC-TiC, and SiC-TiN. Examples of carbon include a mixture of carbonaceous and graphite materials, resin-molded carbon, and sintered carbon. In addition to the above sliding materials, metal materials, resin materials, surface-modified materials (coating materials), and composite materials are also applicable.

[0026] 2 and 3, the rotary seal ring 20 is able to slide clockwise and counterclockwise relative to the mating seal ring, the stationary seal ring 10. The solid and chain line arrows in Figures 2 and 3 indicate the relative rotation direction of the stationary seal ring 10 with respect to the rotary seal ring 20. Note that hereinafter, the direction of the solid line arrows in Figures 2 and 3 may be referred to as the forward rotation direction, and the direction of the chain line arrows as the reverse rotation direction.

[0027] The sliding surface 21 of the rotary seal ring 20 is provided with an introduction groove 23, outer diameter side dynamic pressure generating mechanisms 24, 24' as branch grooves extending toward the sealed fluid side, and inner diameter side dynamic pressure generating mechanisms 25, 25' as branch grooves extending toward the leakage side. The areas other than the introduction groove 23, outer diameter side dynamic pressure generating mechanisms 24, 24', and inner diameter side dynamic pressure generating mechanisms 25, 25' form a flat land 22. Furthermore, the portion of the inner diameter part of the rotary seal ring 20 where the sleeve 2 fits is not shown in the figure.

[0028] The introduction groove 23 is provided concentrically with the rotary seal ring 20. That is, the introduction groove 23 has an endless annular shape.

[0029] On the outer diameter side of the introduction groove 23, sets of outer diameter side dynamic pressure generating mechanisms 24, 24' are arranged at equal intervals in the circumferential direction (for example, eight sets in this embodiment).

[0030] The outer diameter side dynamic pressure generating mechanism 24 has a so-called Rayleigh step shape and is composed of a radial groove 24A and a circumferential groove 24B that serves as a dynamic pressure generating portion. The radial groove 24A extends in the outer diameter direction from the introduction groove 23. The circumferential groove 24B extends in the forward rotation direction from the outer diameter end of the radial groove 24A, substantially parallel to the introduction groove 23.

[0031] Furthermore, the outer diameter side dynamic pressure generating mechanism 24' is disposed at a distance in the opposite rotational direction from the outer diameter side dynamic pressure generating mechanism 24. The outer diameter side dynamic pressure generating mechanism 24' has a symmetrical shape to the outer diameter side dynamic pressure generating mechanism 24 with respect to a line α extending in the radial direction.

[0032] On the inner diameter side of the introduction groove 23, sets of inner diameter side dynamic pressure generating mechanisms 25, 25' are arranged at equal intervals in the circumferential direction (for example, eight sets in this embodiment).

[0033] The inner diameter side dynamic pressure generating mechanism 25 has a so-called Rayleigh step shape and is composed of a radial groove 25A and a circumferential groove 25B that serves as a dynamic pressure generating portion. The radial groove 25A extends in the inner diameter direction from the introduction groove 23. The circumferential groove 25B extends from the inner diameter end of the radial groove 25A in the forward rotation direction substantially parallel to the introduction groove 23.

[0034] Furthermore, the inner diameter side dynamic pressure generating mechanism 25' is disposed at a distance in the opposite rotational direction from the inner diameter side dynamic pressure generating mechanism 25. The inner diameter side dynamic pressure generating mechanism 25' has a symmetrical shape to the inner diameter side dynamic pressure generating mechanism 25 with respect to a line α extending in the radial direction.

[0035] As shown in FIG. 4, the depth D1 of the introduction groove 23 is the same as the depth D2 of the radial groove 24A of the outer diameter side dynamic pressure generating mechanism 24 (D1=D2).

[0036] Furthermore, the depth D2 of the radial groove 24A is deeper than the depth D3 of the radial groove 25A of the inner diameter side dynamic pressure generating mechanism 25 (D2>D3). Specifically, the depth D3 is about half the depth D2.

[0037] As shown in FIG. 5(a), the bottom surface 24b of the circumferential groove 24B is an inclined surface that gradually becomes shallower from the bottom surface 24a of the radial groove 24A toward the land 22.

[0038] As shown in FIG. 5(b), the bottom surface 25b of the circumferential groove 25B is an inclined surface that gradually becomes shallower from the bottom surface 25a of the radial groove 25A toward the land 22.

[0039] Returning to FIG. 3, the circumferential length L1 of the circumferential groove 24B is substantially the same as the circumferential length L2 of the circumferential groove 25B (L1=L2).

[0040] That is, the groove volumes V25, V25' of the inner diameter side dynamic pressure generating mechanisms 25, 25' are smaller than the groove volumes V24, V24' of the outer diameter side dynamic pressure generating mechanisms 24, 24' (V24=V24'>V25=V25').

[0041] Furthermore, the radial separation width L4 between the circumferential groove 25B and the introduction groove 23 is longer than the radial separation width L3 between the circumferential groove 24B and the introduction groove 23 (L3 <L4)。

[0042] Next, the pressure acting on the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotary seal ring 20 will be described.

[0043] When static pressure gas G is supplied as a barrier fluid from the static pressure gas supply source 9, the static pressure gas G passes through the through hole 4a of the housing 4, the space 6, the passage 10a of the stationary seal ring 10, and the supply hole 10b, and is introduced into the introduction groove 23 of the rotary seal ring 20 (see FIG. 1). Note that the static pressure gas G is at a higher pressure than the sealed fluid F.

[0044] 6(a), the static pressure gas G introduced into the introduction groove 23 flows into each of the outer diameter side dynamic pressure generating mechanisms 24, 24' and each of the inner diameter side dynamic pressure generating mechanisms 25, 25'. As a result, the static pressure of the static pressure gas G acts on the sliding surfaces 11 and 21, separating the sliding surfaces 11 and 21 in the axial direction. In this way, the static pressure of the static pressure gas G acts not only on the introduction groove 23 but also on the outer diameter side dynamic pressure generating mechanisms 24, 24' and inner diameter side dynamic pressure generating mechanisms 25, 25' that branch off radially from the introduction groove 23, so that the sliding surfaces 11 and 21 can be separated in a balanced manner.

[0045] 6(b), when the sliding surfaces 11, 21 rotate relative to each other in the forward rotation direction, the static pressure gas G in the outer diameter side dynamic pressure generating mechanisms 24, 24' and the inner diameter side dynamic pressure generating mechanisms 25, 25' moves in the forward rotation direction. As a result, dynamic pressure is generated near the end 24c of the circumferential groove 24B and near the end 25c of the circumferential groove 25B. That is, since dynamic pressure acts on the sliding surfaces 11, 21 in addition to the static pressure of the static pressure gas G, the sliding surfaces 11, 21 can be further separated from each other. Although a slight relative negative pressure is generated in the outer diameter side dynamic pressure generating mechanism 24' and the inner diameter side dynamic pressure generating mechanism 25', the static pressure of the static pressure gas G acts predominantly.

[0046] As described above, the groove volume of the outer diameter side dynamic pressure generating mechanisms 24, 24' is larger than the groove volume of the inner diameter side dynamic pressure generating mechanisms 25, 25', so that a sufficient amount of static pressure gas G can be discharged from the outer diameter side dynamic pressure generating mechanisms 24, 24' to between the sliding surfaces 11, 21, and the sealed fluid F flowing between the sliding surfaces 11, 21 can be prevented from moving toward the inner diameter side.

[0047] On one hand, since a smaller amount of static pressure gas G is supplied to the inner diameter side dynamic pressure generating mechanisms 25, 25' than to the outer diameter side dynamic pressure generating mechanisms 24, 24', it is difficult for the static pressure gas G to leak into the inner space S2. Therefore, it is difficult for the fluid F to be sealed to leak into the inner space S2 together with the static pressure gas G.

[0048] Also, the groove volumes V25, V25' of the inner diameter side dynamic pressure generating mechanisms 25, 25' are smaller than the groove volumes V24, V24' of the outer diameter side dynamic pressure generating mechanisms 24, 24', and the opening areas of the inner diameter side dynamic pressure generating mechanisms 25, 25' are substantially the same as the opening areas of the outer diameter side dynamic pressure generating mechanisms 24, 24'. The average depth of the inner diameter side dynamic pressure generating mechanisms 25, 25' is shallower than the average depth of the outer diameter side dynamic pressure generating mechanisms 24, 24'. As a result, a wide opening area with respect to the sliding surface 11 of the inner diameter side dynamic pressure generating mechanisms 25, 25' can be ensured, and it is easy to separate the sliding surfaces 11, 21 from each other in a balanced manner.

[0049] Also, since each of the outer diameter side dynamic pressure generating mechanisms 24, 24' and the inner diameter side dynamic pressure generating mechanisms 25, 25' communicates with the introduction groove 23, the static pressure gas G can be reliably taken into each of the outer diameter side dynamic pressure generating mechanisms 24, 24' and the inner diameter side dynamic pressure generating mechanisms 25, 25' from the introduction groove 23.

[0050] Also, the separation width L4 between the circumferential groove 25B and the introduction groove 23 is longer than the separation width L3 between the circumferential groove 24B and the introduction groove 23 (L3 < L4). In other words, since the inner diameter side dynamic pressure generating mechanisms 25, 25' extend to a position farther radially from the introduction groove 23 than the outer diameter side dynamic pressure generating mechanisms 24, 24', pressure can be generated in a wide range in the radial direction on the inner space S2 side. Although it is preferable that the separation width L4 is longer than the separation width L3 in that pressure can be generated in a wide range in the radial direction on the leakage side, it is not limited to this, and the separation width L4 may be less than or equal to the separation width L3 (L3 ≧ L4).

[0051] Also, since the introduction groove 23 is annular, pressure is generated in a balanced manner in the circumferential direction, and the sliding surfaces 11, 21 can be stably separated from each other. Also, at the time of relative rotation, it is difficult for dynamic pressure to locally occur in the circumferential direction of the introduction groove 23.

[0052] Furthermore, during forward rotation, dynamic pressure can be generated by the outer diameter side dynamic pressure generating mechanism 24 and the inner diameter side dynamic pressure generating mechanism 25, and during reverse rotation, dynamic pressure can be generated by the outer diameter side dynamic pressure generating mechanism 24' and the inner diameter side dynamic pressure generating mechanism 25'. In other words, dynamic pressure can be generated regardless of the rotation direction of the rotary seal ring 20.

[0053] In this embodiment, the depth D3 of the radial groove 25A is approximately half the depth D2 of the radial groove 24A, but this can be freely changed as long as the depth D3 is shallower than the depth D2.

[0054] In addition, in this embodiment, the depth D1 of the introduction groove 23 is the same as the depth D2 of the radial groove 24A, but this can be freely changed.

[0055] In this embodiment, the bottom surfaces 24b of the circumferential grooves 24B and 25b of the circumferential grooves 25B are inclined surfaces, but they may have a stepped shape that becomes shallower toward the tip. Also, the circumferential grooves 24B and 25B may each have a constant depth in the circumferential direction.

[0056] Furthermore, in this embodiment, the outer diameter side dynamic pressure generating mechanisms 24, 24' and the inner diameter side dynamic pressure generating mechanisms 25, 25' are exemplified as being composed of radial grooves and circumferential grooves, but they may also be, for example, spiral grooves having circumferential and radial components. [Example]

[0057] Next, a mechanical seal according to a second embodiment will be described with reference to Fig. 7. Note that a description of the same configuration as in the first embodiment will be omitted.

[0058] As shown in Fig. 7, the rotating seal ring 220 of the second embodiment is different from the inner diameter side dynamic pressure generating mechanisms 25, 25' of the first embodiment in the shape of the inner diameter side dynamic pressure generating mechanisms 225, 225', and the other configurations are the same as those of the first embodiment. Since the inner diameter side dynamic pressure generating mechanisms 225, 225' have substantially the same configuration, only the inner diameter side dynamic pressure generating mechanism 225 will be described.

[0059] The inner diameter side dynamic pressure generating mechanism 225 has the tip of the circumferential groove 225B, that is, the end portion 225c extending toward the introduction groove 223.

[0060] Specifically, the tip portion of the circumferential groove 225B is bent so as to incline toward the outer diameter side. The distance L10 between the end portion 225c of the circumferential groove 225B and the introduction groove 223 is shorter than the distance L11 between the end portion 225c of the circumferential groove 225B and the inner circumferential surface 220a of the rotating seal ring 220 (L10 < L11). In other words, the end portion 225c of the circumferential groove 225B is arranged closer to the introduction groove 223.

[0061] According to this, during relative rotation, the static pressure gas G in the inner diameter side dynamic pressure generating mechanism 225 is guided to flow out from the end portion 225c of the circumferential groove 225B toward the introduction groove 223, so that the static pressure gas G is less likely to leak into the inner space S2. Therefore, the leakage of the sealed fluid F together with the static pressure gas G into the inner space S2 is reduced.

[0062] In the second embodiment, the form in which the tip portion of the circumferential groove 225B is bent so as to incline toward the outer diameter side is exemplified, but the tip of the circumferential groove may extend in an arc shape toward the outer diameter side. Also, it is not limited to the case where the tip of the circumferential groove is brought closer to the introduction groove by extending from the middle of the circumferential groove toward the introduction groove, and the tip of the circumferential groove may be brought closer to the introduction groove by the circumferential groove extending from the leakage side end of the radial groove toward the introduction groove.

Embodiment

[0063] Next, the mechanical seal according to the third embodiment will be described with reference to Fig. 8. The description of the configurations that are the same as those in the first embodiment will be omitted.

[0064] As shown in Fig. 8, the rotating seal ring 320 of the third embodiment has a plurality of outer diameter side dynamic pressure generating mechanisms 324 and inner diameter side dynamic pressure generating mechanisms 325 provided in the circumferential direction, and the outer diameter side dynamic pressure generating mechanism 24' and the inner diameter side dynamic pressure generating mechanism 25' in the first embodiment are not provided.

[0065] The outer diameter side dynamic pressure generating mechanism 324 is composed of a radial groove 324A and a circumferential groove 324B. The radial groove 324A and the circumferential groove 324B have a constant depth.

[0066] The inner diameter side dynamic pressure generating mechanism 325 is composed of a radial groove 325A and a circumferential groove 325B. The radial groove 325A and the circumferential groove 325B have a constant depth. The depth of the inner diameter side dynamic pressure generating mechanism 325 is shallower than the depth of the outer diameter side dynamic pressure generating mechanism 324.

[0067] Thus, the mechanical seal of the present invention may only correspond to the forward rotation direction.

Embodiment

[0068] Next, the mechanical seal according to the fourth embodiment will be described with reference to Fig. 9. The description of the same components as those in the first embodiment will be omitted.

[0069] As shown in Fig. 9, in the rotating seal ring 420 of the fourth embodiment, the radial groove 424A of the outer diameter side dynamic pressure generating mechanism 424 and the radial groove 425A of the inner diameter side dynamic pressure generating mechanism 425 are not in communication with the introduction groove 423. The outer diameter side dynamic pressure generating mechanism 424' and the inner diameter side dynamic pressure generating mechanism 425' also have a substantially similar configuration.

[0070] Specifically, the radial width L20 of the land 422a partitioning the radial groove 424A and the introduction groove 423 is shorter than the radial width L22 of the introduction groove 423 (L20 < L22). The radial width L20 only needs to be shorter than the radial width L22, and preferably, it may be 1 / 5 times or less.

[0071] <0Similarly, the radial width L21 of the land 422b that partitions the radial groove 425A and the introduction groove 423 is shorter than the radial width L22 of the introduction groove 423 (L21 < L22). Note that the radial width L21 only needs to be shorter than the radial width L22, and preferably may be 1 / 5 times or less.

[0072] According to this, the static pressure gas G is supplied from the introduction groove 423 to the outer diameter side dynamic pressure generation mechanism 424 and the inner diameter side dynamic pressure generation mechanism 425 across the lands 422a and 422b.

[0073] As described above, in the mechanical seal of the present invention, the branch groove extending from the introduction groove only needs to be such that the static pressure gas can move substantially between the introduction groove and the branch groove, and the branch groove may be non-communicating with the introduction groove as in this embodiment.

Embodiment

[0074] Next, the mechanical seal according to Embodiment 5 will be described with reference to FIG. 10. Note that the description of the same configuration as that in Embodiment 1 will be omitted.

[0075] As shown in FIG. 10, the rotary seal ring 520 of this Embodiment 5 includes an introduction groove 523, a plurality of outer diameter side branch grooves 524 extending from the introduction groove 523 to the outer diameter side, and a plurality of inner diameter side branch grooves 525 extending from the introduction groove 523 to the inner diameter side. The inner diameter side branch groove 525 is shallower than the outer diameter side branch groove 524.

[0076] <​​​​​​​​​​​Next, a mechanical seal according to a sixth embodiment will be described with reference to Fig. 11. Note that a description of the same configuration as in the first embodiment will be omitted.

[0079] 11, in the rotary seal ring 620 of this sixth embodiment, the introduction groove 623 is divided at one location in the circumferential direction. In this way, the introduction groove 623 is not limited to an annular groove, and may be substantially C-shaped.

[0080] The introduction groove is not limited to a C-shape, but may be divided into a plurality of grooves in the circumferential direction, or may have an annular wave shape or an annular angular shape. [Example]

[0081] Next, a mechanical seal according to a seventh embodiment will be described with reference to Fig. 12. Note that a description of the same configuration as in the first embodiment will be omitted.

[0082] The mechanical seal to which the rotary seal ring 720 of this seventh embodiment is applied is an outside type in which the atmosphere A communicates with the outer space S1 of the sliding surface 721 and the sealed fluid F is sealed on the inner space S2 side.

[0083] In the seventh embodiment, the groove capacity of the outer diameter side dynamic pressure generating mechanisms 724, 724' is smaller than the groove capacity of the inner diameter side dynamic pressure generating mechanisms 725, 725'.

[0084] In this way, the mechanical seal of the present invention may be applied to an environment in which the sealed fluid space is located on the inner diameter side of the sliding surface and the leakage space is located on the outer diameter side of the sliding surface.

[0085] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0086] For example, in the above-described first to seventh embodiments, the mechanical seal for industrial machinery has been described as an example, but other mechanical seals such as those for automobiles may also be used.

[0087] In addition, in the above-described first to seventh embodiments, the sealed fluid is described as a high-pressure gas, but it is not limited to this and may be a liquid or a low-pressure gas, or a mist-like mixture of liquid and gas.

[0088] In addition, in the above-described Examples 1 to 7, the fluid on the leakage space side was described as being atmospheric air, which is a low-pressure gas, but this is not limited thereto, and the fluid may be a liquid or a high-pressure gas, or a mist-like mixture of liquid and gas, as long as it has a lower pressure than the sealed fluid.

[0089] In addition, in the above-described first to seventh embodiments, the sealed fluid space side is the high pressure side and the leakage space side is the low pressure side, but the sealed fluid space side and the leakage space side may be at approximately the same pressure.

[0090] In addition, in the above-described Examples 1 to 7, the barrier fluid is supplied between the sliding surfaces from the stationary seal ring side, but the barrier fluid may be supplied between the sliding surfaces from the rotating seal ring side. Note that the supply hole and the introduction groove may be formed in the same seal ring.

[0091] In addition, in the above-described Examples 1 to 7, the rotary seal ring is provided with an introduction groove and a branch groove, but the stationary seal ring may be provided with the introduction groove and the branch groove, or the rotary seal ring may be provided with one of the introduction groove and the branch groove, and the stationary seal ring may be provided with the other of the introduction groove and the branch groove. Also, the branch groove having the dynamic pressure generating portion may be in a spiral shape other than a Rayleigh step. [Explanation of symbols]

[0092] 9. Static gas supply source 10 Stationary seal ring (other seal ring) 11 Sliding surface 20 Rotating seal ring (one of the seal rings) 21 Sliding surface 23 Introduction groove 24, 24' outer diameter side dynamic pressure generating mechanism (the branch groove extending to the leakage side) 25, 25' Inner diameter side dynamic pressure generating mechanism (branch groove extending to the sealed fluid side) A. Atmosphere F Sealed fluid G Hydrostatic gas (barrier fluid) S1 Outside space (sealed fluid side space) S2 internal space (leak side space)

Claims

1. A mechanical seal is disposed between a housing and a rotary shaft that rotates relative to the housing, wherein a stationary seal ring fixed to the housing and a rotary seal ring fixed to the rotary shaft rotate relative to each other, separating a sealed fluid space from a leakage space, a supply hole for supplying barrier fluid between the sliding surfaces is formed in at least one of the sliding surfaces of the pair of seal rings, and an introduction groove is formed in the sliding surface of at least one of the pair of seal rings, the introduction groove overlapping with the supply hole in the axial direction and extending in a circumferential direction, branch grooves extending from the introduction groove to the sealed fluid side and the leakage side, respectively; A mechanical seal in which the branch groove extending toward the leakage side has a groove volume smaller than that of the branch groove extending toward the sealed fluid side.

2. 2. The mechanical seal according to claim 1, wherein the branch groove extending toward the leakage side has an average depth shallower than the branch groove extending toward the sealed fluid side.

3. 2. The mechanical seal according to claim 1, wherein a radial end of the branch groove extending toward the leakage side is located at a position radially farther from the introduction groove than a radial end of the branch groove extending toward the sealed fluid side.

4. 2. The mechanical seal according to claim 1, wherein the branch groove extending toward the leakage side and the branch groove extending toward the sealed fluid side communicate with the introduction groove.

5. 5. The mechanical seal according to claim 1, wherein the introduction groove is an endless annular groove.

6. 2. The mechanical seal according to claim 1, wherein the branch groove has a dynamic pressure generating portion extending in the direction of relative rotation of the pair of seal rings.

7. 7. The mechanical seal according to claim 6, wherein an end of the dynamic pressure generating portion in the branch groove extending toward the leakage side extends toward the introduction groove side.

8. 8. The mechanical seal according to claim 7, wherein a radial width between an end of the dynamic pressure generating portion and the leakage side in the branch groove extending toward the leakage side is larger than a radial width between the end of the dynamic pressure generating portion and the introduction groove.

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