JP2019015401A - mechanical seal - Google Patents

Abstract

To provide a mechanical seal capable of making slide surfaces of a sealing ring into a low-friction state.SOLUTION: A mechanical seal 1 is configured to slide a slide surface of one sealing ring with a slide surface of another sealing ring, to prevent sealed fluid from leaking from the inside to the outside in fluid equipment, or from the outside to the inside. At least one sealing ring 5 has a slide surface S1 where a carbon-based hard film 10 is formed on a surface 5a opposite to the other sealing ring 3, of a base material 5A constituting the sealing ring 5, and on the slide surface S1, a recess 9 is formed, where sealed fluid F is encapsulated by a recess part 5b formed at the base material 5A and an opening part 10b formed at the carbon-based hard film 10.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a mechanical seal.

  The mechanical seal is used by being mounted between a housing of a fluid device and a rotating shaft arranged so as to penetrate the housing, and a sliding surface of a stationary seal ring fixed to the housing, and a rotation The sliding surface of the rotary seal ring that rotates together with the shaft is brought into sliding contact to prevent fluid from leaking from the inside of the fluid device to the outside or from the outside to the inside.

  Conventionally, in such a mechanical seal, as disclosed in Patent Document 1, low friction and resistance are provided on one or both of the sliding surface of the stationary sealing ring and the sliding surface of the rotating sealing ring that rotates together with the rotating shaft. Some have carbon-based hard films with excellent wear characteristics.

Japanese Patent Laying-Open No. 2005-061426 (page 4, FIG. 1)

  In the mechanical seal as shown in Patent Document 1, as an example, the sliding surface of the rotary seal ring is provided with a carbon-based hard film, and the stationary seal ring is formed of a hard material such as silicon carbide. In this way, when the sliding surfaces of the stationary sealing ring and the rotating sealing ring are hard materials, the sealed fluid functions as a lubricant by adsorbing the sealed fluid to the sliding surface. The friction coefficient between these sliding surfaces can be reduced. However, in the mechanical seal as in Patent Document 1, a very small amount of sealed fluid that has entered from a slight gap between the stationary seal ring and the rotary seal ring is removed as the stationary seal ring and the rotary seal ring slide. Therefore, there is a problem that the low friction performance due to the use of the hard material cannot be sufficiently enjoyed.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide a mechanical seal capable of bringing the sliding surfaces of the sealing ring into a low friction state.

In order to solve the above problems, the mechanical seal of the present invention is
A mechanical seal that slides the sliding surface of one sealing ring and the sliding surface of the other sealing ring to prevent leakage of the sealed fluid from the inside or outside of the fluid device to the inside,
At least one of the sealing rings is formed as a sliding surface by forming a carbon-based hard film on a surface of the base material constituting the sealing ring facing the other sealing ring. A recess for containing the sealed fluid is formed by a recess formed in the material and an opening formed in the carbon-based hard film.
According to this feature, the sealed fluid enters the recess formed in the sliding surface of one of the sealing rings, and the sealed fluid is contained in the recess. A fluid to be sealed is easily supplied between them and a fluid film is easily formed, and the sliding surfaces of the sealing ring can be maintained in a low friction state while maintaining the characteristics of the carbon-based hard film.

Preferably, at least a part of the carbon-based hard film at least at the opening edge in the circumferential direction of the opening is formed to extend to a position overlapping the inner surface of the recess formed in the base material. .
According to this, when the carbon-based hard film extends to a position overlapping with the inner surface of the concave portion on the upstream side in the flow direction of the sealed fluid, the sealed fluid near the recess extends along the carbon-based hard film. Thus, it is easy to be guided from the opening edge to the bottom side of the recess, and the sealed fluid F easily flows into the recess. In addition, when the carbon-based hard film extends to a position overlapping the inner surface of the concave portion on the downstream side in the flow direction of the sealed fluid, the sealed fluid in the recess extends along the carbon-based hard film from the opening edge. Therefore, the sliding surfaces can be brought into a low friction state. In addition, since the tip edge of the opening edge portion of the carbon-based hard film does not contact the sliding surface of the other sealing ring, it is possible to prevent the carbon-based hard film from being peeled off by relative rotation between the sliding surfaces of the sealing ring.

Preferably, at least the opening edge in the rotational circumferential direction of the opening formed in the carbon-based hard film forms an inclined surface that inclines in the bottom direction of the recess of the base material.
According to this, along the opening edge of the carbon-based hard film forming the inclined surface, the fluid to be sealed on the sliding surface easily enters the recess, and from the inside of the recess to the sliding surface along the carbon-based hard film. Easy to flow out.

Preferably, at least an opening edge in the rotational circumferential direction of the opening formed in the carbon-based hard film forms a curved surface that is inclined toward the bottom of the recess of the base material.
According to this, since the sliding surface of the carbon-based hard film and the opening edge portion are smoothly connected, the sealed fluid easily enters the bottom side of the recess from the sliding surface, and the carbon-based fluid from the recess. It tends to flow out to the sliding surface of the hard film.

Preferably, an inclined surface inclined in the bottom direction is formed at the edge of the concave portion of the base material.
According to this, the carbon-based hard film can be easily formed on the inclined surface which is a shape along the inner surface of the concave portion of the base material by forming the hard base film by CVD or PVD on the base material. Can be formed.

Preferably, a curved surface inclined in the bottom direction is formed at the edge of the concave portion of the base material.
According to this, the carbon-based hard film is easily formed on the base material by CVD or PVD, so that the opening edge of the carbon-based hard film is a curved surface that is shaped along the inner surface of the concave portion of the base material. can do.

Preferably, one opening edge portion and the other opening edge portion in the rotational circumferential direction of the opening formed in the carbon-based hard film are formed symmetrically with respect to the radial direction.
According to this, since the opening edge portion of the carbon-based hard film in the circumferential direction of rotation is symmetrical, the flow of the sealed fluid entering the recess and the flow of the sealed fluid flowing out of the recess are approximated. Generation of turbulent flow in the station can be prevented.

Preferably, the carbon-based hard film is continuously formed from the opening edge of the opening to the bottom of the recess formed in the base material.
According to this, not only can the trouble of masking the bottom surface of the recess when the carbon-based hard film is formed be eliminated, but the entire inside of the recess, that is, the surface of the recess is formed of the carbon-based hard film. The fluidity of the sealed fluid is stabilized and turbulence can be prevented.

Preferably, the surface roughness of the inner surface of the recess formed in the substrate is rougher than the surface roughness of the opposing surface of the substrate.
According to this, the carbon-based hard film is firmly fixed to the inner side surface of the concave portion of the base material.

It is sectional drawing which shows the mechanical seal in Example 1 of this invention. 3 is a partially enlarged cross-sectional view showing a sliding contact structure between seal rings in Example 1. FIG. (A) is the figure which looked at the mating ring in Example 1 in the axial direction from the opposing surface side with a seal ring, (b) is an axial direction from the opposing surface side with a mating ring. FIG. It is a figure which shows the sliding surface of the seal ring and mating ring in Example 1. FIG. It is the elements on larger scale which looked at the recess of the mating ring in Example 2 of this invention from the opposing surface side with a seal ring to the axial direction. (A) is AA sectional drawing of FIG. 5 in Example 2, (b) is BB sectional drawing of FIG. It is a partially expanded sectional view which shows the recess of the mating ring in Example 3 of this invention. It is a partially expanded sectional view which shows the recess of the mating ring in Example 4 of this invention. It is a partially expanded sectional view which shows the recess of the mating ring in Example 5 of this invention. It is a partially expanded sectional view which shows the recess of the mating ring in Example 6 of this invention. It is a partially expanded sectional view which shows the modification 1 of a mechanical seal. It is a partially expanded sectional view which shows the modification 2 of a mechanical seal. It is a partially expanded sectional view which shows the modification 3 of a mechanical seal. It is a partially expanded sectional view which shows the reference example 1 of a mechanical seal. It is a partially expanded sectional view which shows the reference example 2 of a mechanical seal. It is a partially expanded sectional view which shows the reference example 3 of a mechanical seal.

  EMBODIMENT OF THE INVENTION The form for implementing the mechanical seal which concerns on this invention is demonstrated below based on an Example.

  The mechanical seal according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a longitudinal sectional view showing an example of a mechanical seal. The mechanical seal 1 seals a sealed fluid on the machine side M of a fluid device that is about to leak from the outer periphery of the sliding surface toward the inner peripheral direction. One side of the type that is provided so as to be rotatable integrally with the rotary shaft 8 via the sleeve 2 on the side of the rotary shaft 8 that drives a pump impeller (not shown) on the high-pressure fluid side. An annular seal ring (rotating seal ring) 3 that is a sliding part of the above and an annular main ring that is the other sliding part provided in a non-rotating state and axially movable in the housing 4 of the fluid device. And a ting ring (stationary sealing ring) 5.

  The mating ring 5 and the seal ring 3 are configured to slide closely between the sliding surfaces S1 and S2 by a coiled wave spring 6 and a bellows 7 that urge the mating ring 5 in the axial direction. That is, the mechanical seal 1 prevents the sealed fluid from flowing out from the outer periphery of the rotating shaft 8 to the atmosphere side A on the sliding surfaces S1 and S2 of the mating ring 5 and the seal ring 3. is there.

  In the mating ring 5, the base 5A (see FIG. 2) is made of hard ceramics (silicon nitride, zirconia, alumina, SiC, etc.), and as shown in FIG. Further, a carbon-based hard film 10 is formed. In this embodiment, the carbon-based hard film 10 is formed over the entire facing surface 5 a, and the sliding surface 10 a of the carbon-based hard film 10 constitutes the sliding surface S 1 of the mating ring 5. The carbon-based hard film 10 is made of a carbonaceous material excluding diamond, such as fullerene, carbon nanotube, graphene, graphite, amorphous carbon, and carbine containing no hydrogen, by physical production or chemical method. The film is formed by a conventional manufacturing method and is formed by a DLC (diamond-like carbon) film, a diamond coating, a carbon film, or the like, and is excellent in low friction and wear resistance. The carbon-based hard film 10 is formed by using a technique such as CVD or PVD after forming a recess 5b (recess portion) described later on the facing surface 5a of the base 5A.

  As shown in FIG. 3, a recess 5b is formed on the facing surface 5a of the base 5A. Four recesses 5b are provided in the circumferential direction of the substrate 5A. An opening 10b is formed in the carbon-based hard film 10 at a position corresponding to the recess 5b, and a recess is formed in the sliding surface S1 of the mating ring 5 by the recess 5b and the opening 10b (opening portion). 9 (recess) is configured. The recess 9 is formed with an axial depth of 10 μm.

  On the other hand, similarly to the mating ring 5, the seal ring 3 is made of a hard ceramic (silicon nitride, zirconia, alumina, SiC, etc.) as a base 3A (see FIG. 2). The carbon-based hard film 11 is formed on the opposite surface 3a, and the sliding surface 11a of the carbon-based hard film 11 constitutes a sliding surface S2.

  As shown in FIG. 3, a recess 3b is formed on the facing surface 3a of the substrate 3A. Four recesses 3b are equally arranged in the circumferential direction of the substrate 3A. An opening 11b is formed in the carbon-based hard film 11 at a position corresponding to the recess 3b, and the recess 3b and the opening 11b form the sliding surface S2 of the seal ring 3 and the outer diameter direction of the seal ring 3, respectively. An opening groove 90 (recess) is formed. The groove 90 is formed to have an axial depth of 10 μm. When the axial depth dimension is 10 μm or more, the recess 9 mainly serves to hold the sealed fluid, and the seal ring 3 There is almost no dynamic pressure generating action for separating the mating ring 5 in the axial direction by the pressure of the fluid.

  As shown in FIG. 1, the recess 9 formed in the sliding surface S1 of the mating ring 5 and the groove 90 formed in the facing surface 3a of the seal ring 3 are partially in the radial direction. The concavity 9 and the groove 90 communicate with each other when facing each other. Therefore, when the machine side M is filled with the sealed fluid, the sealed fluid F around the seal ring 3 of the mechanical seal 1 enters the groove 90 of the seal ring 3 and then the recesses of the groove 90 and the mating ring 5. When 9 faces, it enters the recess 9. The sealed fluid F that has entered the recess 9 is adsorbed to the surface of the sliding surface S2 of the seal ring 3 in a region facing the recess 9, and the seal ring 3 is rotated by relative rotation between the seal ring 3 and the mating ring 5. The sliding surface S2 and the sliding surface S1 of the mating ring 5 enter a slight gap. The sealed fluid F that has entered the gap is adsorbed by the sliding surface S1 of the mating ring 5, and the frictional force between the sliding surface S1 and the sliding surface S2 can be reduced. It should be noted that the sealed fluid F in the recess 9 and the groove 90 is in a small amount from a slight gap between the sliding surface S2 of the seal ring 3 and the sliding surface S1 of the mating ring 5 even when the relative rotation is stopped. Infiltrate.

  According to this, the sealed fluid F enters the recess 9 formed in the sliding surface S1 of the mating ring 5, and the sealed fluid F is contained in the recess 9. The sealed fluid F is supplied between the sliding surfaces S2 of the opposing seal ring 3 to easily form a fluid film, and the sliding surfaces S1 and S2 are brought into a low friction state while maintaining the characteristics of the carbon-based hard film. Can be maintained.

  As shown in FIG. 4, the sliding surface 10a of the carbon-based hard film 10 of the mating ring 5 is a region (β1) that faces the groove 90 of the seal ring 3 in order from the outer diameter side and does not have the recess 9. ), A region (β2) facing the groove 90 and having the recess 9, a region (β3) not having the groove 90 of the seal ring 3 and having the recess 9, and a seal portion 3 c that is annularly continuous with the seal ring 3 And it can be divided into a region (β4) that does not face the groove 90 of the seal ring 3 and does not have the recess 9.

Since the region β1 faces the groove 90 of the seal ring 3, the sealed fluid F in the groove 90 is directly adsorbed on the surface, and therefore the sealed fluid F is relatively easily adsorbed.
Since the region β2 faces the groove 90, the sealed fluid F in the groove 90 is directly adsorbed on the surface. In addition, since the sealed fluid F is adsorbed on the sliding surface 11a of the carbon-based hard film 11 of the seal ring 3 in the portion facing the recess 9 of the region β2, the region β2 and the sliding surface 11a Excellent slidability.
The sealed fluid F is adsorbed to the region β3 through the sliding surface 11a of the carbon-based hard film 11 of the seal ring 3 at a portion facing the recess 9 of the region β3.
In the region β4, it is difficult for the sealed fluid F to enter between the seal ring 11 and the seal portion 11c that continues in an annular shape, and the sealed fluid F is prevented from leaking to the atmosphere side A.

  Thus, in the regions β1 to β3, the frictional force in sliding between the sliding surfaces S1 and S2 is reduced, and in the region β4 and the seal portion 11c, the frictional force in sliding between the sliding surfaces S1 and S2 is reduced. Although the reduction of is limited, the sealing property of the mechanical seal can be reliably ensured. Moreover, since sliding surface S1, S2 contact | abuts over radial direction, the tilting of the mating ring 5 and the seal ring 3 can be prevented, and the sealing performance of the mechanical seal 1 can be maintained in a high state.

  Furthermore, the most sealed fluid F is located at the center (β3 in the mating ring 5) of the portion where the sealed fluid F is adsorbed at the sliding contact portion between the sliding surface S1 and the sliding surface S2. Become. According to this, since many sealed fluids F are located between the sliding surfaces S1 and S2, the slidability 9 and the groove 90 are opposed to and communicate with each other. The effect of rotational resistance due to turbulent flow generated at the time can be compensated with high slidability.

  Further, since the groove 90 opens in the outer diameter direction of the seal ring 3, that is, opens to the sealed fluid side, the machine side M of the fluid device is in a high pressure state (during operation of the fluid device). In this case, since the sealed fluid F is constantly supplied into the groove 90, the sliding surface 10 a (sliding surface S 1) of the carbon-based hard film 10 that accompanies sliding between the mating ring 5 and the seal ring 3. The state in which the sealed fluid F can be adsorbed to the sliding surface 10a of the carbon-based hard film 10 can be maintained against the removal of the sealed fluid F.

  Further, the sealed fluid F adsorbed on the sliding surface S1 of the carbon-based hard film 10 passes through the sliding surface 10a of the portion where the sealed fluid F is adsorbed, and the sliding surface S2 of the seal ring 3 that is opposed thereto. Therefore, the friction between the sliding surface S1 of the mating ring 5 and the sliding surface S2 of the seal ring 3 can be effectively reduced.

  Further, in addition to the carbon-based hard film 10 having a single low friction property formed on the facing surface 5 a of the mating ring 5, the above-described sealed fluid is used as the sliding surface 10 a of the carbon-based hard film 10. Further, the friction of the sliding surface S1 of the mating ring 5 is reduced.

  Further, since the carbon-based hard film 10 is formed by CVD or PVD with the concave portion 5b of the base material 5A facing upward, the surface roughness of the inner side surface 5c of the concave portion 5b formed on the base material 5A is roughened. The degree (for example, arithmetic average roughness Ra) is formed to be rougher than the surface roughness of the facing surface 5a, and forms the carbon-based hard film 10 on the surface of the inner side surface 5c when the carbon-based hard film 10 is formed. Material is easy to deposit. The carbon-based hard film 10 can be firmly fixed from the facing surface 5a of the base 5A to the inner surface 5c of the recess 5b. Furthermore, the carbon-based hard film 10 can be formed with a thin film on the inner surface 5c side as compared with the facing surface 5a side, so that the internal capacity of the recess 9 can be secured.

  Next, a mechanical seal according to the second embodiment will be described with reference to FIGS. The description of the same configuration as that of the above embodiment is omitted.

  As shown in FIG. 5 and FIG. 6, four concave portions 15 b are equally formed on the facing surface 15 a of the base material 15 </ b> A of the mating ring 15 in the circumferential direction. The recess 15b is formed in a substantially rectangular shape in plan view, and the inner side surface 15c is an inclined surface that inclines from the opposing surface 15a toward the bottom surface 15d.

  The carbon-based hard film 20 is formed so that the opening edge portion 21 forming the opening portion 20b overlaps the inner side surface 15c of the recess portion 15b. As described above, the opening edge 21 of the carbon-based hard film 20 is overlapped with the inner surface 15c of the recess 15b, so that the sealed fluid F is opened from the sliding surface 20a of the carbon-based hard film 20 to the opening edge 21. The sealed fluid F is likely to flow into the recess 19 constituted by the recess 15b of the base material 15A and the opening 20b of the carbon-based hard film 20 through the recess 15b. Further, the sealed fluid F in the recess 19 easily flows out to the surface 20a side of the carbon-based hard film 20 through the opening edge 21, and the sliding surfaces S1 and S2 can be brought into a low friction state. Furthermore, since the tip edge of the opening edge 21 of the carbon-based hard film 20 does not contact the sliding surface S2 of the seal ring 3, the relative rotation between the mating ring 15 and the sliding surfaces S1 and S2 of the seal ring 3 is performed. It is possible to prevent the carbon-based hard film 20 from peeling off. In addition, the sealed fluid F tends to flow along the surface of the opening edge 21, and the recess 19 is caused by friction generated by the relative rotation of the sliding surfaces S 1 and S 2 and the entrance and exit of the sealed fluid F into the recess 19. It is difficult for turbulent flow to occur inside, and peeling of the carbon-based hard film 20 due to the influence of the turbulent flow can be prevented.

  Further, the inner side surface 15c of the recess 15b is an inclined surface that is inclined from the opening edge toward the bottom surface 15d, and the opening edge 21 of the carbon-based hard film 20 formed by CVD or PVD on the base material 15A. Is a shape along the inner side surface 15c of the recess 15b of the substrate 15A, that is, an inclined surface. According to this, the sealed fluid F easily enters the bottom surface 15d side of the recess 15b along the opening edge 21 of the carbon-based hard film 20 forming the inclined surface, and the sliding surface 20a of the carbon-based hard film 20 is present. Easy to flow to the side. Further, since the opening edge 21 of the carbon-based hard film 20 in the rotational circumferential direction is symmetrical, the flow of the sealed fluid F that enters the recess 19 and the flow of the sealed fluid F that flows out of the recess 19. Therefore, generation of turbulent flow in the recess 19 can be prevented.

  Next, a mechanical seal according to the third embodiment will be described with reference to FIG. The description of the same configuration as that of the above embodiment is omitted.

  As shown in FIG. 7, the carbon-based hard film 30 is formed so that the opening edge portion 31 forming the opening portion 30b overlaps the inner side surface 25c of the recess portion 25b of the base material 25A, and the opening portion 30b and the recess portion are formed. A recess 29 is formed by 25b. The inner side surface 25c of the recess 25b is a curved surface that inclines in the direction of the bottom surface 25d from the opposing surface 25a, and the opening edge 31 of the carbon-based hard film 30 formed by CVD or PVD on the base material 25A The shape is a curved surface along the inner side surface 25c of the recess 25b of the material 25A. According to this, since there is no step or abrupt change in the angle between the sliding surface 30 a of the carbon-based hard film 30 and the opening edge 31, the sealed fluid F is the sliding surface of the carbon-based hard film 30. It is easy to enter from 30 a along the opening edge 31 to the bottom surface 15 d side of the recess 25 b without a large change in flow velocity, and to easily flow out to the sliding surface 30 a side of the carbon-based hard film 30.

  Next, a mechanical seal according to Embodiment 4 will be described with reference to FIG. The description of the same configuration as that of the above embodiment is omitted.

  As shown in FIG. 8, the inner side surface 35c constituting the recess 35b of the base 35A has a shape that intersects the opposing surface 35a perpendicularly in the direction of the bottom surface 35d. The carbon-based hard film 40 has a shape in which an opening edge 41 forming the opening 40b intersects the sliding surface 40a perpendicularly along the inner surface 35c. According to this, the sealed fluid F stored in the recess 39 when the relative rotation between the seal ring 3 and the mating ring 35 is stopped or at a low speed as compared with the above-described inclined surface shape or curved surface shape. High ability to hold

  Next, a mechanical seal according to Embodiment 5 will be described with reference to FIG. The description of the same configuration as that of the above embodiment is omitted.

  As shown in FIG. 9, in the carbon-based hard film 50, the opening edge portion 51 that forms the opening portion 50b is formed on the inner side surface of the concave portion 45b of the base material 45A on both sides in the rotational circumferential direction of the mating ring 45. Each of the inner surfaces of the recess 45b of the base material 45A is formed so as not to overlap the inner side surfaces 46c on both sides in the radial direction. According to this, at the time of relative rotation of the seal ring 3 and the mating ring 45, dynamic pressure or negative pressure is generated on both sides in the rotational circumferential direction of the recess 49, respectively, to the recess 49 of the sealed fluid F. As compared to the both sides in the radial direction, the amount of entering and exiting is increased. Therefore, the opening edge portion 51 of the carbon-based hard film 50 is formed so as to overlap the inner side surfaces 45c on both sides in the rotational circumferential direction of the mating ring 45, so that the recess 49 of the sealed fluid F particularly in the rotational circumferential direction. The effect that makes it easy to go in and out is obtained. In addition, by omitting the portion formed overlapping the inner side surfaces 46c on both sides in the radial direction, it is possible not only to prevent excessive entry and exit of the sealed fluid F stored in the radial direction, but also the inside of the recess 49. Large capacity can be secured.

  Next, a mechanical seal according to Embodiment 6 will be described with reference to FIG. The description of the same configuration as that of the above embodiment is omitted.

  As shown in FIG. 10, the carbon-based hard film 60 is formed so as to cover the entire surface of the recess 55b from the facing surface 55a of the base 55A to the bottom surface 55d of the recess 55b. According to this, not only the trouble of masking the bottom surface 55d of the recess 55b when the carbon-based hard film 60 is formed, but also the entire surface of the recess 55b, that is, the recess 59 is formed of the carbon-based hard film 60. The fluidity of the sealed fluid F inside the recess 59 is stabilized, and the occurrence of turbulence can be prevented. Further, the entire surface of the concave portion 55b in the base material 55A is covered with the carbon-based hard film 60, so that impurities such as carbon dioxide generated from the surface of the concave portion 55b by sliding during relative rotation enter the sealed fluid F. Can be prevented.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, in the above-described embodiment, the carbon-based hard film is described as an example in which both the mating ring ring and the seal ring are formed. However, the carbon hard film is not limited to this and is formed on either the mating ring side or the seal ring side. It is good also as a structure to be.

  Moreover, in the said Example, although the example where four recesses are equally arranged in the circumferential direction and the example formed cyclically | annularly were demonstrated, it is not restricted to this, For example, one or more 5 or more in the circumferential direction It is not limited to what is formed in the location and is equally distributed. Furthermore, a plurality of annular recesses may be formed in the radial direction.

  In addition, the carbon-based hard film has been described with a configuration that is formed in the same shape along the shape of the inner surface that forms the concave portion of the base material. However, the configuration is not limited to this, and for example, shown in Modification 1 of FIG. As described above, even if the inner side surface 65c constituting the concave portion 65b of the base material 65 intersects the opposing surface 65a perpendicularly in the direction of the bottom surface 65d, the peripheral shape of the opening edge portion 71 of the carbon-based hard film 70 Regardless of the shape of the base material 65, a shape having an inclined surface 72 between the sliding surface 70a and the opening edge 71 may be used. The angle at which the sliding surface 70a and the opening edge 71 intersect may be a curved surface.

  Further, as shown in Modification 2 of FIG. 12, the opening edge 81 of the carbon-based hard film 80 is formed up to the boundary between the inner surface 75c of the recess 75b and the opposing surface 75a of the base 75A, and the inner surface 75c. The end edge of the opening edge 81 may have a curved shape inclined toward the boundary between the inner surface 75c and the opposing surface 75a, so that the sealed fluid F is in the recess 79. It becomes easy to go in and out. Note that the edge of the opening edge 81 may be an inclined surface.

  In Examples 2 and 4 shown in FIGS. 6 and 8, the angle at which the sliding surface of the carbon-based hard film and the opening edge intersect may be a curved surface.

  Moreover, although the recessed part opened to an outer-diameter side was formed in the seal ring, and it demonstrated with the structure which introduces the to-be-sealed fluid F into the recessed part of the facing mating ring, it is not restricted to this, For example, FIG. 13 shows. As described above, the concave surface 85b that opens to the seal ring side and the outer diameter side is formed in the facing surface 85a of the base material 85A of the mating ring 85, and the carbon-based hard film 91 opens to the seal ring side and the outer diameter side. A recess 89 that opens to the seal ring side and the outer diameter side may be formed. In this case, since the sealed fluid F can be introduced into the recess 89 by the single recess 89 formed in the mating ring 85, the groove on the seal ring side may be omitted.

  In addition, the recess is not limited to a configuration in which the depth is 10 μm, and if the recess is in the range of 6 μm to 14 μm, the sliding surface S1 of the mating ring and the sliding surface S2 of the seal ring are slid. The effect of reducing friction in motion is relatively high. In the demonstration experiment, when the depth of the recess is 5 μm, 10 μm, and 15 μm, the sealing performance of the mechanical seal and the sliding performance between the sliding surface S1 and the sliding surface S2 are determined. When comparing with the above, the most ideal value was 10 μm (sliding property 5 μm <sliding property 15 μm <sliding property 10 μm).

  The mechanical seal may be an outside type that restricts leakage of the sealed fluid from the inner diameter side to the outer diameter side.

  Further, the mechanical seal has been described by taking a static type as an example, but it may be a rotary type.

  The fluid to be sealed is not limited, but examples thereof include fluids, particularly water, oils mixed with additives, and gases such as nitrogen.

  Further, the recess may be formed after the carbon-based hard film is formed on the base material of the mechanical seal.

In addition, the shape of the recess is not limited, such as a groove or dimple continuous in the circumferential direction. Furthermore, the shape may generate dynamic pressure in the recess.
[Reference Example 1]

  Next, the mechanical seal according to Reference Example 1 will be described with reference to FIG. The description of the same configuration as that of the above embodiment is omitted.

  In the mating ring 105, a carbon-based hard film 110 is formed over the entire opposing surface 105a of the base material 105A, and the surface 110a constitutes the sliding surface S1. On the other hand, no carbon-based hard film is formed on the seal ring 103, and the mating ring 105 side and the outer diameter direction of the seal ring 103 are formed on the facing surface 103 a (sliding surface S 2) facing the mating ring 105. Grooves 190 are formed in the respective openings.

When the machine side M is filled with the sealed fluid, the sealed fluid F enters the groove 190 from the periphery of the seal ring 103, and faces the groove 190 on the sliding surface 110 a of the carbon-based hard film 110 of the mating ring 105. In the region, the sealed fluid F is adsorbed so as to even out the minute irregularities formed on the sliding surface 110a, and the frictional force between the sliding surface S1 and the sliding surface S2 becomes low.
[Reference Example 2]

  Next, a mechanical seal according to Reference Example 2 will be described with reference to FIG. The description of the same configuration as that of the above embodiment is omitted.

As shown in FIG. 15, an annular groove 191 having an axial depth of 10 μm and continuous in the sliding direction is formed on the surface 113 a (sliding surface S <b> 2) of the seal ring 113 facing the mating ring 105. Is formed. The groove 191 has a structure that does not open in the outer diameter direction of the seal ring 113. The groove 191 includes an opposing surface 113 a of the seal ring 113 and a sliding surface 110 a of the carbon-based hard film 110 of the mating ring 105. The sealed fluid F that has entered through the slight gap is stored. Thus, since the groove 191 is formed in an annular shape, the sealed fluid F is applied to the sliding surface 110a of the carbon-based hard film 110 constituting the sliding surface S1 of the mating ring 105 facing the groove 191. Intermittent contact and efficient adsorption.
[Reference Example 3]

  Next, a mechanical seal according to Reference Example 3 will be described with reference to FIG. The description of the same configuration as that of the above embodiment is omitted.

  As shown in FIG. 16, an annular groove 141 </ b> A having an axial depth of 10 μm and continuous in the sliding direction is formed on the surface 123 a of the seal ring 123 facing the mating ring 105. Four grooves 141 </ b> A are provided in the circumferential direction of the seal ring 123, and the grooves 141 </ b> A communicate with the introduction grooves 141 </ b> B each having an axial depth of 10 μm and opening in the outer diameter direction of the seal ring 123. Yes. According to this, when the pressure is applied to the sealed fluid side of the fluid device, the sealed fluid F is continuously supplied into the groove 141A via the introduction groove 141B. Further, the fluid F to be sealed comes into contact with the sliding surface 110a of the carbon-based hard film 110 constituting the sliding surface S2 of the mating ring 105 facing the annular groove 141A and the introducing groove 141B, and efficiently adsorbs it. Can do.

1 Mechanical seal 3 Seal ring (sealing ring)
3A Substrate 3a Opposing surface 5 Mating ring (sealing ring)
5A Substrate 5a Opposing surface 5b Recessed portion 5c Inner side surface 5d Bottom surface 9 Recessed portion 10 Carbon-based hard film 10a Sliding surface (sliding surface S1)
10b Opening 11 Carbon hard film 11a Sliding surface (sliding surface S2)
15 Mating ring 15A Base material 15b Recess 19 Recess 20b Opening 20 Carbon hard film 20a Sliding surface 21 Opening edge 31 Opening edge 35a Opposing surface 35b Recess 35c Inner side 35d Bottom 41 Opening edge 45c Inner side 46c Inner side A Air side F Sealed fluid M Machine side

Claims (9)

A mechanical seal that slides the sliding surface of one sealing ring and the sliding surface of the other sealing ring to prevent leakage of the sealed fluid from the inside or outside of the fluid device to the inside,
At least one of the sealing rings is formed as a sliding surface by forming a carbon-based hard film on a surface of the base material constituting the sealing ring facing the other sealing ring. A mechanical seal characterized in that a recess for containing the sealed fluid is formed by a recess formed in the material and an opening formed in the carbon-based hard film.   At least a part of the carbon-based hard film at least at the opening edge in the rotational circumferential direction of the opening is formed to extend to a position overlapping the inner surface of the recess formed in the base material. The mechanical seal according to claim 1.   The opening edge portion in at least the rotational circumferential direction of the opening portion formed in the carbon-based hard film forms an inclined surface that inclines in the bottom direction of the concave portion of the base material. Mechanical seal.   The opening edge of at least the rotational circumferential direction of the opening formed in the carbon-based hard film forms a curved surface that inclines in the bottom direction of the recess of the base material. mechanical seal.   The mechanical seal according to any one of claims 1 to 3, wherein an inclined surface inclined in a bottom direction is formed at an edge of the concave portion of the base material.   The mechanical seal according to any one of claims 1 to 3, wherein a curved surface inclined in a bottom direction is formed at an edge of the concave portion of the base material.   The one opening edge part and the other opening edge part of the rotation circumferential direction in the opening part formed in the carbon-based hard film are formed symmetrically with respect to the radial direction. The mechanical seal according to 3 or 4.   The mechanical carbon film according to any one of claims 1 to 7, wherein the carbon-based hard film is continuously formed from an opening edge of the opening to a bottom of a recess formed in the base material. seal.   9. The surface roughness of the inner surface of the recess formed in the base material is rougher than the surface roughness of the opposing surface of the base material. Crab mechanical seal.

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