JP7350449B2 - mechanical seal - Google Patents

Description

The present invention relates to mechanical seals.

Mechanical seals are used to prevent leakage of sealed fluids. A mechanical seal includes a pair of sealing rings whose sliding surfaces slide against each other as they rotate relative to each other. In such mechanical seals, in recent years, it has been desired to reduce the energy lost due to sliding, and mechanical seals that improve the lubricity between sliding surfaces have been developed.

For example, the mechanical seal shown in Patent Document 1 includes a first sealing ring that rotates together with a rotating shaft and a second sealing ring that is fixed to a housing, and slides on the sliding surfaces of these sealing rings. This prevents the sealed fluid sealed in the space on the outer diameter side from leaking into the space on the inner diameter side. Further, a plurality of strain control recesses each having a notch and opening on the inner diameter side are arranged in the second sealing ring in the circumferential direction. When the pressure of the fluid to be sealed acts on the second sealing ring, the second sealing ring is deformed using the strain control recess as a starting point, causing distortion, thereby causing unevenness on the sliding surface of the second sealing ring. is starting to form.

Japanese Patent Application Publication No. 2009-79634 (Page 7, Figure 3)

According to the mechanical seal disclosed in Patent Document 1, when the first sealing ring and the second sealing ring rotate relative to each other, the convex portion formed on the sliding surface of the second sealing ring moves against the sliding surface of the first sealing ring. It functions as a substantial sliding surface that slides on the sliding surface, and the fluid to be sealed is introduced into the recess formed in the sliding surface of the second sealing ring and discharged between the sliding surfaces. Dynamic pressure is generated, the sliding surfaces are separated by the dynamic pressure, and the fluid to be sealed is interposed between the sliding surfaces, thereby improving lubricity and achieving low friction. However, in the mechanical seal of Patent Document 1, since the strain control recess is open on the inner diameter side, which is the atmosphere side, contaminants such as dust existing in the inner diameter space enter the strain control recess. The accumulation of contaminants may reduce the amount of deformation of the strain control concave portion, inhibit the deformation of the second sealing ring, and there is a risk that it may not be possible to effectively form irregularities on the sliding surface. Ta.

The present invention has been made with attention to such problems, and an object of the present invention is to provide a mechanical seal that can suppress the entry of contaminants into the concave portion for strain control .

In order to solve the above problems, the mechanical seal of the present invention has the following features:
A mechanical seal having a pair of sealing rings having sliding surfaces that slide relative to each other and sealing a fluid to be sealed,
One of the sealing rings has a plurality of cut grooves spaced apart in the circumferential direction on the side opposite to the sliding surface in the axial direction and opening on the back side,
The notch groove is defined by a first side plate portion disposed on the sealed fluid side and a second side plate portion spaced apart from the first side plate portion in the radial direction,
An annular secondary seal member is disposed between the first side plate portion and the space on the sealed fluid side.
According to this, since the notched groove is provided, one of the sealing rings is deformed by the pressure of the fluid to be sealed, and it is possible to form irregularities on the sliding surface. Furthermore, since the second side plate portion is provided on the side of the cutout groove opposite to the sealed fluid side, it is possible to suppress contamination from entering the cutout groove from the space on the opposite side to the sealed fluid side. This makes it possible to secure the deformation allowance for one of the sealing rings due to the notched groove .

The opening of the notch groove may be covered by a cover member.
According to this, since the opening of the notch groove is closed by the cover member, it is possible to reliably prevent contaminants from entering the notch groove.

The second side plate portion may be formed thinner than the first side plate portion.
According to this, since the second side plate part has lower structural strength than the first side plate part, the diameter of the portion of one sealing ring on the opposite side to the sealed fluid side is reduced or expanded in the radial direction. Easy to do.

The cutout groove may have a shape extending to the sliding surface side from a virtual center of gravity in a radial cross section of the one sealing ring.
According to this, one sealing ring has a deep notch groove, and the axial length of the part on the sliding surface side that partitions the notch groove is short, so the internal stress caused by deformation is absorbed by the one sealing ring. Easy to transmit to the sliding surface of the ring.

Each of the notched grooves may be symmetrical in the circumferential direction with respect to a reference plane extending radially from the center of the one sealing ring.
According to this, when one sealing ring receives pressure from the fluid to be sealed, deformation occurs symmetrically in the circumferential direction of the notched groove with the reference plane as the center, so that the sliding ring located at the circumferential center of the notched groove The moving surface can be expanded greatly.

The one sealing ring may be integrally formed.
According to this, one of the sealing rings is integrally formed, and the strength per unit volume of the one of the sealing rings is constant, so that the one of the sealing rings can be reliably deformed and can be easily processed.

1 is a side sectional view showing an example of a mechanical seal in Example 1 of the present invention. FIG. FIG. 3 is a diagram of the sliding surface of the stationary sealing ring viewed from the axial direction. FIG. 3 is a view of the back surface of the stationary sealing ring viewed from the axial direction. (a) is a sectional view taken along line AA in FIG. 3, and (b) is a view taken along arrow B in FIG. FIG. 3 is a side cross-sectional view showing the stationary seal ring attached to the housing and the seal cover. (a) is a schematic diagram showing a pressure receiving part where the pressure of the fluid to be sealed acts on the static sealing ring, and (b) is a schematic diagram showing the state in which the diameter of the static sealing ring is reduced from the state of (a) due to the pressure of the fluid to be sealed. It is a diagram. FIG. 3 is a schematic diagram showing the amount of bulge of the thin plate portion of the stationary sealing ring. 7 is a view taken along arrow C in FIG. 6. FIG. It is a figure which shows the stationary sealing ring in Example 2 of this invention.

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

A sliding component according to Example 1 will be described with reference to FIGS. 1 to 8. In this embodiment, the outer diameter side of the sealing ring constituting the mechanical seal will be described as the sealed liquid side (high pressure side), and the inner diameter side will be explained as the leak side, which is the atmosphere side (low pressure side). Furthermore, the sliding surface side of the stationary sealing ring will be described as the front side.

A mechanical seal 1 for general industrial machinery shown in FIG. 1 seals a sealed liquid F that tends to leak from the outer diameter side of mutually opposing sliding surfaces 11 and 21 toward the inner diameter side (that is, toward the atmosphere A side). It is an inside type seal cover 5 fixed to a housing 4 constituting an attached device, and a stationary seal ring 10 as one of the annular seal rings provided in a state where rotation is regulated. , and a rotary sealing ring 20 as the other annular sealing ring provided on the rotating shaft 3 via a fixed sleeve 2 so as to be rotatable integrally with the rotating shaft 3. The rotary seal ring 20 is attached to the stationary sleeve 2 so as to be movable in the axial direction, and the rotary seal ring 20 is biased in the axial direction toward the stationary seal ring 10 by a spring (not shown). By rotating along with the rotating shaft 3, the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 closely slide against each other. As will be described later, the sliding surface 11 of the stationary sealing ring 10 is the end surface of the nose portion 12 that is formed to protrude in the axial direction from the end surface 10a on the rotating sealing ring 20 side (hereinafter also referred to as the front side). The sliding surface 11 is a flat surface extending perpendicularly to the axial direction over its entire surface in a natural state before pressure is applied by a sealed liquid F to be described later. Further, the sliding surface 21 of the rotary sealing ring 20 is a flat surface extending perpendicularly to the axial direction over the entire surface.

The stationary sealing ring 10 and the rotating sealing ring 20 are typically formed of a combination of SiC (i.e., hard materials) or a combination of SiC (i.e., hard material) and carbon (i.e., soft material), but are not limited to this. Any material that is used as a sliding material for mechanical seals can be used. Note that SiC includes sintered bodies using boron, aluminum, carbon, etc. as sintering aids, as well as materials consisting of two or more phases with different components and compositions, such as SiC in which graphite particles are dispersed, and SiC. There are reactive sintered SiC, SiC-TiC, SiC-TiN, etc. made of Si, and as carbon, carbon that is a mixture of carbonaceous and graphite, resin-molded carbon, sintered carbon, etc. can be used. In addition to the above-mentioned sliding materials, metal materials, resin materials, surface-modified materials (for example, coating materials), composite materials, etc. can also be used.

As shown in FIGS. 2 and 3, the stationary seal ring 10 is formed in a short cylindrical shape that is annular when viewed in the axial direction. The nose portion 12 is formed in an annular shape, and a portion of the nose portion 12 in the radial direction protrudes toward the ring 20 side. Furthermore, on the back side of the sliding surface 11 of the stationary sealing ring 10 (that is, the side opposite to the rotating sealing ring 20), a plurality of notch grooves 13 that are open on the back side and extend in the axial direction are arranged at equal intervals in the circumferential direction. It is formed. In this embodiment, eight cutout grooves 13 are formed in the circumferential direction, but the number of cutout grooves 13 is not limited to this embodiment.

In other words, the stationary sealing ring 10 has a plurality of thick plate portions 14 as thick wall portions spaced apart between a plurality of notch grooves 13 spaced apart in the circumferential direction, and an adjacent thick plate portion 14 as a thick wall portion spaced apart from each other. The front side portions of the plate portions 14 are connected to each other, and a thin plate portion 15 that is thinner in the axial direction than the thick plate portion 14 and a high pressure side portion of the adjacent thick plate portions 14 extending in the axial direction from the thin plate portion 15 are connected. A side plate part 16 that is thinner in the radial direction than the thick plate part 14 and a low pressure side part of the adjacent thick plate parts 14 extending in the axial direction from the thin plate part 15 are connected, and the side plate part 16 is thinner in the radial direction than the thick plate part 14. A side plate portion 18 that is thin in the direction is formed. That is, the side plate part 16 functions as a first side plate part that partitions the notch groove 13 from the space on the side of the sealed liquid F, and the side plate part 18 functions as a first side plate part that partitions the space on the side of the atmosphere A and the notch groove 13. It functions as a second side plate section. Further, a stepped portion 16a that forms a step in the radial direction is formed on the thin plate portion 15 side of the side plate portion 16, and a reduced diameter portion 5a (FIG. 1 ) are engaged in the axial direction to prevent the stationary sealing ring 10 from coming off. Note that the front surface of the thick plate portion 14 on the rotary seal ring 20 side and the front surface of the thin plate portion 15 on the rotary seal ring 20 side are formed flush with each other, and the end surface 10a of the stationary seal ring 10 is It consists of Further, the outer circumferential surface of the thick plate portion 14 and the outer circumferential surface of the side plate portion 16 are formed flush with each other, and constitute the outer circumferential surface of the stationary sealing ring 10, and the inner circumferential surface of the thick plate portion 14 and The inner circumferential surface of the side plate portion 18 is formed flush with the inner circumferential surface of the stationary sealing ring 10 . The stepped portion 16a and the reduced diameter portion 5a may be omitted if the stationary sealing ring 10 is prevented from coming off by other means. In that case, the stationary sealing ring 10 may have a uniform circumferential surface, or It may have an uneven shape.

As shown in FIGS. 3 and 4, the notch groove 13 has a rectangular shape when viewed from the back in the axial direction. Specifically, the notch groove 13 includes a pair of surfaces 13c that face each other in the circumferential direction and extend in parallel, and a surface 13b that extends perpendicularly to these surfaces 13c and connects the outer diameter side portions of the surfaces 13c (i.e., a notch). The outer diameter surface 13b of the groove 13, the surface 13d extending in an arc shape so as to connect the inner diameter sides of the pair of surfaces 13c (that is, the inner diameter surface 13d of the notched groove 13), and the front end of each surface 13c, surface 13b, and surface 13d. It is composed of a surface 13e extending so as to orthogonally connect the side parts (that is, the end surface 13e of the notched groove 13 on the sliding surface 11 side, that is, the back surface of the thin plate part 15). The circumferential dimension L1 of the end 13a of the side plate 18 on the radially opposite side to the sealed liquid F (see FIG. 5) and on the back side (that is, the end 13a on the inner diameter side and the back side of the side plate 18) is: The distance L2 in the circumferential direction between the end portions 14a of adjacent notch grooves 13 on the radially opposite side and the back side of the sealed liquid F (see FIG. 5), in other words, the inner diameter side and the back side end of the thick plate portion 14 It is shorter than the dimension L2 of the circular arc wire extending in the circumferential direction of the section (L1<L2). Note that the circumferential dimension L10 of the outer diameter side and rear side end of the side plate portion 18 (that is, the circumferential direction dimension L10 of the rear side end of the surface 13d) is the inner diameter end of the side plate portion 18. It is slightly longer than the circumferential dimension L1 of 13a (L1<L10). Furthermore, since the circumferential dimension L10 of the outer diameter side and rear side end of the side plate portion 18 is the same as the circumferential direction dimension of the inner diameter side and rear side end of the notch groove 13, hereinafter, simply It is also expressed as the circumferential dimension L10 of the notch groove 13.

Further, the axial dimension L3 of the notched groove 13 is longer than half the axial length of the thick plate portion 14, and longer than the circumferential dimension L10 of the notched groove 13 (L10<L3). The shape of the notch groove 13 is defined by a plane S (hereinafter simply referred to as reference plane S) extending radially from the center of the stationary sealing ring 10 so as to pass through the circumferential center of the notch groove 13. ), and as a result, when the stationary sealing ring 10 receives the pressure of the sealed liquid F, the deformation will be symmetrical about the reference plane S, as described later. The deformation stress is concentrated in the circumferential center of the thin plate portion 15 that partitions the notched groove 13, and the direction of the deformation is toward the sliding surface 11, so the deformation stress is transmitted to the sliding surface 11. As a result, the sliding surface 11, which will be described later, bulges out efficiently.

Furthermore, as shown in FIG. 4(a), the stationary sealing ring 10 is formed with a cutout groove 13 that opens on the back side. It has a biased shape, and the virtual center of gravity G of the stationary seal ring 10 in the radial cross section is located closer to the sliding surface 11 than the axial center C of the stationary seal ring 10 . Note that the virtual center of gravity G means the center of gravity in a plane in a cross section in the radial direction, and is referred to with the imaginary suffix. Further, as shown in FIG. 4(b), the axial dimension L3 of the notched groove 13 is longer than the axial dimension L9 from the back surface of the stationary sealing ring 10 to the virtual center of gravity G. In other words, the cutout groove 13 has a shape extending from the opening M on the back side beyond the virtual center of gravity G to the sliding surface 11 side.

As will be described later, when the stationary sealing ring 10 receives the pressure of the liquid to be sealed F, the side plate deforms with the vicinity of the corner of the thin plate part 15 and the side plate part 16 as a deformation starting point T (see FIG. 4(a)). The portion on the back side of the stationary sealing ring 16 moves in the inner diameter direction, and the portion on the back side of the stationary sealing ring 10 contracts in diameter. In this way, the notch groove 13 has a shape that extends from the opening M on the back side beyond the virtual center of gravity G to the sliding surface 11 side, and the axial dimension L3 of the notch groove 13, in other words, the side plate part 16. Since the dimension from the back surface to the deformation starting point T can be secured long, the diameter of the portion on the back side of the stationary seal ring 10 can be greatly reduced, and since the thickness of the thin plate portion 15 in the axial direction is formed thin, the stationary seal ring 10 can be The structure is such that internal stress generated when the diameter of the sealing ring 10 is reduced is easily transmitted to the thin plate portion 15.

The axial thickness L4 of the thin plate portion 15 is shorter than the axial thickness L5 of the thick plate portion 14 (L4<L5).

The thickness L6 of the side plate portion 16 is shorter than the radial thickness L7 of the thick plate portion 14 (L6<L7). Further, the thickness L8 of the side plate portion 18 is shorter than the radial thickness L7 of the thick plate portion 14 (L8<L7). Further, the thickness L8 of the side plate portion 18 is shorter than the thickness L6 of the side plate portion 16 (L8<L6).

Further, as particularly shown in FIG. 4(a), the nose portion 12 is disposed at the radially central portion of the end surface 10a of the stationary sealing ring 10. Specifically, the inner diameter end 11a of the sliding surface 11 of the stationary sealing ring 10 is disposed on the outer diameter side of the inner diameter surface 13d of the notch groove 13, which is the outer diameter surface of the side plate portion 18, so that the sliding surface 11 of the stationary sealing ring 10 The outer diameter end 11b of the dynamic surface 11 is arranged on the inner diameter side of the outer diameter surface 13b of the notched groove 13, which is the inner diameter surface of the side plate portion 16. Specifically, the nose portion 12 is arranged so as not to overlap the side plate portions 16 and 18 in the axial direction, and to be slightly closer to the side plate portion 18. In other words, the nose portion 12 is arranged so as not to overlap the side plate portions 16 and 18 in the axial direction. It is arranged on the inner radial side of the radially central portion of the end surface 10a of 10. In this embodiment, the nose portion 12 does not overlap the side plate portions 16 and 18 in the axial direction. , or may partially overlap with the side plate portion 18 in the axial direction.

Next, the form of the stationary sealing ring 10 when the mechanical seal 1 is used will be explained based on FIGS. 5 to 8.

As shown in FIG. 5, when the stationary sealing ring 10 is attached to the housing 4 and the seal cover 5, an annular groove 4a is formed on the front surface of the housing 4, and a groove 4a is arranged in the groove 4a. An endless secondary seal 6, for example, an O-ring, is provided uniformly in the circumferential direction (that is, has the same shape in the circumferential direction), and is provided on the outer side of the back side of the stationary sealing ring 10 (that is, the side opposite to the rotating sealing ring 20). The sealed liquid F enters between the stationary seal ring 10 on the outer diameter side of the secondary seal 6 and the seal cover 5, and the sealed liquid F enters between the stationary seal ring 10 on the outer diameter side of the secondary seal 6 and the seal cover 5, and Intrusion into the notch groove 13 (ie, the atmosphere A side) is prevented. That is, the outer circumferential surface of the stationary sealing ring 10, specifically the outer circumferential surfaces of the thick plate part 14, thin plate part 15, side plate part 16, and nose part 12, absorb the pressure of the sealed liquid F from the outer diameter toward the inner diameter. It is configured as a pressure receiving section 17 that receives the pressure. That is, the secondary seal 6 may be disposed around the stationary sealing ring 10 closer to the liquid to be sealed F than the notch groove 13 and the liquid to be sealed F will not flow into the notch groove 13 . Note that the force from the liquid to be sealed F acts on the front surface of the thin plate section 15 (that is, the end surface 10a) and the front surface of the stepped section 16a in the axial direction toward the rear side in addition to the pressure receiving section 17. It acts dominantly on the outer circumferential surface, particularly on the outer circumferential surface of the thick plate portion 14, causing the stationary sealing ring 10 to contract in diameter as will be described later. In addition, the inner circumferential surface of the stationary sealing ring 10, specifically, the inner circumferential surfaces of the thick plate part 14, thin plate part 15, side plate part 18, and nose part 12, are placed on the atmosphere A side having a lower pressure than the liquid F to be sealed. facing.

Further, when the stationary seal ring 10 is attached to the housing 4 and the seal cover 5, the opening M on the back side of the notch groove 13 is closed by the housing 4 as a cover member. That is, the cutout groove 13 does not communicate with the space on the side of the liquid to be sealed F, and communicates with the space on the side of the atmosphere A through a small gap between the side plate portion 18 and the housing 4. Note that an O-ring may be disposed between the space on the side of the atmosphere A and the side plate portion 18 so that the notch groove 13 is closed in a sealed manner.

As shown in FIGS. 6(a) and 6(b), when the pressure receiving part 17 of the stationary sealing ring 10 receives the pressure of the liquid to be sealed, the strength is reduced compared to other parts because of the notch groove 13. The weaker portion of the stationary sealing ring 10 on the back side in the axial direction becomes smaller in diameter due to the pressure. Specifically, as particularly shown in FIG. 6(b), when the pressure receiving part 17 of the stationary sealing ring 10 receives the pressure of the sealed liquid F, the portion on the back side of the adjacent thick plate part 14 in the radial direction The central portions are not connected to each other and are free ends, and the inner diameter side plate portion 18 is weaker in strength than the outer diameter side side plate portion 16, so the back side portion of the thick plate portion 14 and The inner diameter side portions are pressed toward each other in the circumferential direction, and the stationary sealing ring 10 is reduced in diameter. Further, the thin plate portion 15 and the nose portion 12 have an endless annular shape without the cutout groove 13 and have high structural strength, so that the closer they are to the sliding surface 11 in the axial direction, the less deformation occurs. Therefore, the diameter of the stationary sealing ring 10 is greatly reduced on the back side, and the diameter is reduced small on the sliding surface 11 side. As a result, as shown in the right diagram of FIG. 6(b), the thin plate part 15, which is thinner than the thick plate part 14, can be bulged toward the rotary sealing ring 20 in the axial direction due to the internal stress generated by this pressing. It looks like this. Further, when the thin plate portion 15 is bulged toward the rotary sealing ring 20 side, the nose portion 12 is also deformed so as to bulge along the thin plate portion 15 . In addition, in FIG. 6, for convenience of explanation, the amount of deformation of the side plate portion 16 and the amount of bulge of the thin plate portion 15 are shown larger than they actually are.

Furthermore, as shown in FIG. 6(b), the notch groove 13 has a side plate part 16 on the outer diameter side and a side plate part 18 on the inner diameter side, so that the thin plate part 15 is deformed at the radial center part. It's easy to do. In addition, since the side plate part 18 is formed thinner than the side plate part 16 and has weaker structural strength, the inner diameter side part of the thin plate part 15 is more likely to deform than the outer diameter side part in the radial center part. The amount of bulge toward the rotary sealing ring 20 at 15 is larger on the inner diameter side in the radial center. Furthermore, since the nose portion 12 is disposed on the inner diameter side of the radially central portion of the end surface 10a of the stationary sealing ring 10, it is deformed by the large expansion of the thin plate portion 15. Further, the thin plate portion 15 has a larger amount of bulge toward the rotary sealing ring 20 at the center in the circumferential direction than at both ends in the circumferential direction. More specifically, regarding the bulging aspect of the thin plate portion 15, as shown in FIG. A portion slightly on the inner diameter side of the central portion bulges out the most, and bulges out from this portion toward the periphery. In FIG. 7, the amount of bulge of the thin plate portion 15 is schematically illustrated by halftone dots, and the higher the density of the halftone dot, the larger the amount of bulge in the axial direction. Furthermore, in FIG. 7, illustration of the nose portion 12 is omitted for convenience of explanation.

As shown in FIG. 8, the thin plate portion 15 is bulged toward the rotary sealing ring 20, so that a portion of the sliding surface 11 corresponding to the circumferential center of the thin plate portion 15 is formed as a convex portion 8. Microscopically, the convex portion 8 becomes a portion that comes into contact with the sliding surface 21 of the rotary sealing ring 20, and the portions corresponding to both ends of the thin plate portion 15 in the circumferential direction and the thick plate portion 14 are formed as the recessed portion 7. Microscopically, this is a portion that does not come into contact with the sliding surface 21 of the rotary sealing ring 20. Between the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20, portions that contact each other and portions that are spaced apart in the axial direction occur alternately at equal intervals in the circumferential direction. In this direction, concave portions 7 are regularly formed between convex portions 8 in the circumferential direction. Note that since the sealed liquid F has a higher viscosity than gas, it does not leak from the recess 7 into the low-pressure side space when the mechanical seal 1 is stopped, or the amount that leaks is very small.

When the stationary seal ring 10 and the rotating seal ring 20 rotate relative to each other, since the convex portion 8 is formed at the circumferential end of the recess 7, the liquid F to be sealed that has flowed into the recess 7 is transferred to the rotary seal ring 20. It follows the rotational direction, and the pressure of the sealed liquid F is increased in the recess 7, and the increased pressure flows out from the vicinity of the convex part 8, which is the end of the recess 7, to its surroundings. As a result, the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 are slightly separated, and the sealed liquid F existing between the sliding surfaces 11 and 21 provides good lubrication. It has come to form a state. In particular, when the thick plate portions 14 described above are pressed closer to each other in the circumferential direction, a plurality of bulging convex portions 8 are formed in the thin plate portion 15 spaced apart in the circumferential direction. The sealed liquid F can be easily held in the concave portion 7 formed between the convex portions 8, and dynamic pressure can be generated by the rotation of the rotary sealing ring 20.

As explained above, since the stationary sealing ring 10 is provided with the cutout groove 13, when the thick plate part 14 and the side plate part 16 receive pressure from the sealed liquid F in the inner diameter direction, the thick plate part 14 In addition to being able to bring the thick plate parts 14 closer to each other, the internal stress caused by the proximity of the thick plate parts 14 to the thin plate part 15 is effectively transmitted to the thin plate part 15, and the sliding surface 11 is locally bulged out to form unevenness on the sliding surface 11. It is structured so that it can be Since the side plate part 18, which is a second side plate part, is provided on the atmosphere A side, which is the opposite side of the sealed liquid F side of the notch groove 13, the side plate part 18 is provided as a second side plate part. It is possible to suppress the intrusion of contaminants such as dust. According to this, since the accumulation of contaminants in the notched groove 13 is suppressed, the amount of deformation of the stationary sealing ring 10 due to the notched groove 13 can be secured, and unevenness can be reliably formed on the sliding surface 11. .

Furthermore, when the stationary sealing ring 10 is attached to the housing 4 and the seal cover 5, the opening M on the back side of the notch groove 13 is closed by the housing 4, so that entry into the notch groove 13 is prevented. It can definitely be prevented. Note that the cover member that covers the opening M of the notch groove 13 is not limited to the housing 4, and may be, for example, a plate member different from the housing 4, a cap, or the like.

Moreover, the notch groove 13 has an axial dimension L3 larger than a circumferential dimension L10. Therefore, the larger L3 is, the closer the notch groove 13 can be formed to the sliding surface 11, making it easier to bulge out the thin plate part 15, and the smaller L10 is, the closer the stationary sealing ring 10 is cut out. The volume occupied by the cutout groove 13 is small, and the strength of the stationary sealing ring 10 can be maintained. In addition, since the secondary seal 6 is pressed against the end surface of the back side of the stationary seal ring 10 (that is, the side opposite to the rotating seal ring 20), a large pressure receiving area can be obtained, and the stationary seal ring 10 can be reduced in diameter. Easy to do. Thereby, the recess 7 can be reliably formed between the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20, and the liquid to be sealed F can be held within the recess 7. The dynamic pressure generated in the recess 7 allows the sliding surfaces 11 and 21 to be slightly spaced apart, thereby improving sliding performance.

Further, the side plate portion 18 provided on the atmosphere A side is formed thinner than the side plate portion 16 provided on the sealed liquid F side. Specifically, the thickness L8 of the side plate portion 18 is formed shorter than the thickness L6 of the side plate portion 16, and since the side plate portion 18 has lower structural strength than the side plate portion 16, the stationary seal ring is formed in the radial direction. 10 can be easily reduced in diameter toward the atmosphere A side.

Further, an end surface 13e of the notched groove 13 on the sliding surface 11 side is arranged closer to the sliding surface 11 than the virtual center of gravity G of the stationary sealing ring 10 in the axial direction. In this way, the end face 13e of the notched groove 13 on the sliding surface 11 side is disposed closer to the sliding surface 11 than the virtual center of gravity G of the stationary sealing ring 10, so that the end face 13e of the notched groove 13 on the sliding surface 11 side By bringing the end face 13e of the side plate closer to the sliding surface 11 side, the thin plate part 15 can be formed thinner in the axial direction, and by ensuring a long dimension from the back surface of the side plate part 16 to the deformation starting point T, the static sealing ring 10 can be made thinner. Since the diameter of the portion on the back side can be greatly reduced, internal stress caused by deformation can be easily transmitted to the sliding surface 11 side of the stationary sealing ring 10.

Further, the side plate portion 16 connects the outer diameter side portions of the adjacent thick plate portions 14, and the notch groove 13, which is the space between the adjacent thick plate portions 14, is the space on the side of the liquid to be sealed F. Since the notched groove 13 and the sealed liquid F do not communicate with each other, a large pressure difference between the notch groove 13 and the sealed liquid F can be ensured, and the expansion of the thin plate portion 15 toward the rotary sealing ring 20 can be performed reliably.

Further, since the axial thickness L4 of the thin plate portion 15 is thinner than the axial thickness L5 of the thick plate portion 14, the thin plate portion 15 expands with high responsiveness following the diameter reduction of the stationary sealing ring 10. You can make it come out.

Furthermore, since the thickness L6 of the side plate 16 and the thickness L8 of the side plate 18 are thinner than the radial thickness L7 of the thick plate 14, the side plate 16 follows the diameter reduction of the stationary sealing ring 10. And the side plate portion 18 can be deformed with high responsiveness.

Further, since the dimension L2 of the circumferential inner diameter side portion of the thick plate portion 14, which has higher structural strength than the thin plate portion 15, is longer than the circumferential dimension L10 of the notch groove 13, the strength of the stationary sealing ring 10 can be ensured. In addition, since the length of the thin plate portion 15 in the circumferential direction is short, when the stationary sealing ring 10 contracts in diameter, the deformation occurs locally and concentrates, so the amount of bulge toward the rotating sealing ring 20 must be large. I can do it.

Further, in the thin plate part 15, the thick plate part 14 and the thin plate part 15 are equally distributed in the circumferential direction, and can form unevenness evenly on the sliding surface 11, so that the static sealing ring 10 and the rotating The slidability with the sealing ring 20 can be further improved.

Further, on the sliding surface 11 side of the thin plate portion 15 and the thick plate portion 14, a nose portion 12 protruding in the axial direction is provided in an annular shape over the circumferential direction. According to this, the strength of the stationary sealing ring 10 is improved by the nose portion 12, so that the thin plate portion 15 can be formed thin.

Further, the nose portion 12 is disposed closer to the inner diameter side than the side plate portion 16, and the bulge of the thin plate portion 15 in the axial direction can be suitably transmitted to the nose portion 12.

In addition, the stationary sealing ring 10 has a thick plate part 14, a thin plate part 15, a side plate part 16, a side plate part 18, and a nose part 12 that are integrally formed. Compared to a sealing ring, the thin plate part 15 and the side plate part 16 can be deformed more reliably. Moreover, since the notch groove 13 can be formed by cutting out the annular member, the stationary sealing ring 10 can be easily processed.

Next, a mechanical seal according to Example 2 will be described with reference to FIG. 9. Note that explanations of the same and overlapping configurations as those of the previous embodiment will be omitted.

As shown in FIG. 9, in the stationary sealing ring 100 according to the second embodiment, a side plate part 161 as a first side plate part extends in the axial direction from the inner diameter side of the thin plate part 151, and the inner diameter of the adjacent thick plate parts 141 is The side plate portion 181 as a second side plate portion extends in the axial direction from the outer diameter side of the thin plate portion 151 to connect the outer diameter side portions of the adjacent thick plate portions 141. It is formed to connect. Further, when the stationary seal ring 100 is attached to the housing 4 and the seal cover 5, the secondary seal 6 disposed in the groove 4a' formed in the housing 4 is attached to the back side of the stationary seal ring 100. It is in pressure contact with the end face on the inner diameter side, and the liquid to be sealed F is arranged on the inner diameter side of the sliding surface 111. That is, the inner circumferential surface of the stationary sealing ring 100, specifically the inner circumferential surfaces of the thick plate part 141, thin plate part 151, side plate part 161, and nose part 121, are arranged so that the sealed liquid F flows from the inner diameter toward the outer diameter. It serves as a pressure receiving part 171 that receives pressure.

As shown in FIGS. 9(b) and 9(c), when the pressure receiving part 171 of the stationary seal ring 100 receives the pressure of the liquid to be sealed F, the stationary seal ring 100 deforms toward the outer diameter side, and each thick plate part 141 move in the outer radial direction so as to move away from each other, thereby making it possible to contract the thin plate part 151, which is thinner than the thick plate part 141, toward the back side.

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 any changes or additions that do not depart from the gist of the present invention are included in the present invention. It will be done.

In the embodiment described above, the circumferential dimension L10 of the notch groove 13 is shorter than the dimension L2 of the circumferential inner diameter side of the thick plate part 14. It may be formed longer than the direction. In this case, the circumferential dimension of the recess formed between the sliding surfaces when the stationary sealing ring is reduced in diameter can be increased.

Further, in the above embodiment, the thick plate portions 14 are arranged equally in the circumferential direction, but the circumferential length and number of the thick plate portions can be freely changed.

Further, in the above embodiment, the notch groove 13 is formed in the stationary sealing ring 10, but the notch groove 13 may be formed in the rotating sealing ring 20, or the notch groove 13 is formed in both. may have been done.

Furthermore, in the above embodiments, the fluid to be sealed is a liquid, but the fluid to be sealed may be a gas, or may be a mist mixture of a liquid and a gas.

Further, in the above embodiment, the secondary seal member is arranged on the back side of the stationary sealing ring, but the secondary sealing member is not limited to this, and may be arranged on the outer diameter side of the stationary sealing ring, for example. . That is, it is sufficient if high pressure is applied to the surface of the side plate portion on the sealed fluid side, for example, the outer peripheral surface of the side plate portion 16 in the first embodiment.

Further, in the above embodiment, the second side plate provided on the atmosphere A side is thinner than the first side plate provided on the sealed liquid F side, but the present invention is not limited to this. do not have. Moreover, it is preferable that the structural strength of the second side plate part is lower than that of the first side plate part. For example, if the second side plate is made of a member having lower structural strength than the first side plate, the thickness of the second side plate may be equal to or greater than the thickness of the first side plate.

1 Mechanical seal 3 Rotating shaft 4 Housing (cover member)
6 Secondary seal (secondary seal member)
7 Concave portion 8 Convex portion 10 Stationary sealing ring (one sealing ring)
11 Sliding surface 12 Nose part 13 Notch groove (groove part)
14 Thick plate part (thick part)
15 Thin plate part 17 Pressure receiving part 20 Rotating sealing ring (other sealing ring)
21 Sliding surface 100 Stationary sealing ring 121 Nose section 200 Stationary sealing ring 215 Thin plate section 231 Notch groove 241 Thick plate section (thick wall section)
300 Stationary sealing ring 315 Thin plate part 331 Notch groove 341 Thick plate part (thick part)
400 Stationary sealing ring 415 Thin plate part 431 Notch groove 441 Thick plate part (thick part)
A Atmosphere F Sealed liquid (sealed fluid)

Claims (6)

A mechanical seal having a pair of sealing rings having sliding surfaces that slide relative to each other and sealing a fluid to be sealed,
One of the outer diameter side and inner diameter side of the pair of sealing rings is a sealed fluid side, and the other is a leakage side,
One of the sealing rings has a plurality of notched grooves arranged on the radial leakage side and spaced apart in the circumferential direction and opening at least on the back side,
The notch groove is defined by a first side plate portion disposed on the sealed fluid side in the radial direction , and a second side plate portion spaced apart from the first side plate portion on the leakage side in the radial direction ,
An annular secondary seal member is disposed between the notch groove and the space on the sealed fluid side ,
The secondary seal member is a mechanical seal disposed on the rear end surface of the first side plate portion . The mechanical seal according to claim 1, wherein the opening of the notch groove is covered with a cover member. The mechanical seal according to claim 1 or 2, wherein the second side plate portion is formed thinner than the first side plate portion. The mechanical seal according to any one of claims 1 to 3, wherein the notched groove has a shape extending to the sliding surface side from a virtual center of gravity in a radial cross section of the one sealing ring. 5. The mechanical seal according to claim 1, wherein each of the notch grooves is symmetrical in the circumferential direction with respect to a reference plane extending radially from the center of the one sealing ring. 6. The mechanical seal according to claim 1, wherein said one sealing ring is integrally formed.

Images