JP7577607B2 - Mechanical seal - Google Patents

Description

The present invention relates to a mechanical seal.

In various rotating equipment, a mechanical seal is known as a device for sealing the internal fluid between the equipment casing and the rotating shaft, which includes a rotating seal ring that rotates integrally with the rotating shaft and a stationary seal ring that is provided on the equipment casing to seal between the rotating seal ring and the stationary seal ring (see, for example, Patent Document 1).

JP 2019-138334 A

In rotating equipment, the rotating shaft may tilt relative to the equipment casing, for example, due to the assembly accuracy of each part. In this case, it is necessary to attach the mechanical seal to the rotating equipment in accordance with the tilt of the rotating shaft. In the mechanical seal disclosed in Patent Document 1, the stationary unit includes an outer ring having a concave curved surface on the inner circumference and an inner ring having a convex curved surface on the outer circumference that contacts the concave curved surface, making it possible to tilt the inner ring relative to the outer ring, which is in a fixed state. Therefore, when attaching the mechanical seal to the rotating equipment, the inner ring and the stationary seal ring that is integral with the inner ring are tilted in accordance with the tilt of the rotating shaft, thereby ensuring the sealing performance between the stationary seal ring and the rotating seal ring.

In the mechanical seal disclosed in Patent Document 1, the sealing performance is maintained if the rotating shaft rotates while maintaining the inclination angle from the time of initial assembly. However, if the rotating shaft changes its inclination angle while rotating, the stationary unit cannot follow the rotating shaft, which can make it difficult to maintain the sealing performance.

The present invention aims to provide a mechanical seal that can maintain its sealing performance even when the inclination angle of the rotating shaft changes as it rotates.

(1) The mechanical seal of the present invention comprises a rotating unit having a rotating seal ring and capable of rotating integrally with a rotating shaft, a stationary unit having a stationary seal ring for sealing between the rotating seal ring and the rotating seal ring, and a support unit supporting the stationary unit, the support unit having an outer ring having a concave surface on its inner periphery that is shaped along a virtual spherical surface having a center point on the axis of the support unit, the stationary unit having a spherical ring whose rotation relative to the outer ring is restricted and which has a convex surface on its outer periphery that makes surface contact with the concave surface, a retaining ring that is integral with the spherical ring and holds the stationary seal ring, and a bearing block that is integral with the spherical ring and is interposed between the spherical ring and the rotating shaft or the rotating unit to cause the spherical ring to follow the inclination of the rotating shaft.

With the mechanical seal, when the inclination angle of the axis of the rotating shaft changes while the rotating shaft rotates, the spherical ring follows the inclination angle due to the bearing block, and the inclination angle of the axis of the spherical ring also changes. Even if the inclination angle of the spherical ring changes, the outer ring supports the spherical ring by allowing the change with the concave curved surface. In accordance with the change in the inclination angle of the spherical ring, the inclination angle of the stationary seal ring held by the retaining ring that is integral with the spherical ring also changes. As a result, even if the inclination angle of the rotating shaft changes while rotating, there is no change in the relative position of the rotating seal ring and the stationary seal ring, and the sealing performance is maintained.

(2) When the rotating shaft whirls, the rotating shaft changes its inclination angle and is displaced (eccentric) in the radial direction. Therefore, preferably, the support unit has a support block provided with a guide groove that supports the outer ring so as to be displaceable in the radial direction.
With this configuration, even if the rotating shaft changes its inclination angle and displaces radially, the outer ring supporting the spherical ring displaces radially, allowing the stationary unit to follow the rotating shaft. As a result, there is no change in the relative position of the rotating seal ring and the stationary seal ring, and sealing performance is maintained.

(3) In particular, when the rotating shaft is tilted such that the tilt angle changes with a position on one axial side or the other axial side of the mechanical seal as a base point, an axial displacement component occurs between the rotating shaft and the rotating unit and the stationary unit. Therefore, preferably, the bearing block has a rolling bearing having a plurality of rollers, which allows axial displacement between the rollers and the raceway surfaces with which the rollers roll and make contact, and a bearing case which holds the rolling bearing and is connected to the spherical ring.
According to the above configuration, the rotating shaft and the rotating unit are rotatable relative to the bearing block of the stationary unit, and axial displacement is permitted between the bearing block and the rotating shaft and the rotating unit. In other words, axial slip occurs between the rollers and the raceway surface, and the axial displacement component occurring between the rotating shaft and the rotating unit and the stationary unit is absorbed by the rolling bearing. As a result, the rotating shaft follows the mechanical seal smoothly.

(4) In addition, the mechanical seal has an anti-rotation mechanism that restricts rotation of the spherical ring relative to the outer ring, in which the outer ring has a pin that protrudes toward the spherical ring, and the spherical ring has a recess that accommodates the tip of the pin.
According to the above configuration, even if the rotating shaft rotates together with the rotating unit and the stationary seal ring receives a rotational force from the rotating seal ring, causing the spherical ring of the stationary unit to rotate, the tip of the pin of the outer ring comes into contact with the inner surface of the recess provided in the spherical ring, preventing the spherical ring from rotating.

(5) In the case of the mechanical seal described in (2) above, since the outer ring is radially displaceable by the guide groove, the outer ring may also require a rotation prevention mechanism. In this case, the outer ring has a second pin protruding toward the support block as a second rotation prevention mechanism for restricting the rotation of the outer ring relative to the support block, and the support block is provided with a second recess for accommodating the tip of the second pin.
According to the above configuration, even if the rotating shaft rotates together with the rotating unit and the stationary seal ring receives a rotational force from the rotating seal ring and the outer ring attempts to rotate along with the spherical ring of the stationary unit, the tip of the second pin held by the outer ring comes into contact with the inner surface of the second recess provided in the support block, preventing the outer ring from rotating.

(6) Also, preferably, one or both of the guide groove and the sliding surface of the outer ring that comes into sliding contact with the guide groove are provided with a coating for reducing a coefficient of friction.
According to this configuration, the outer ring can be smoothly displaced in the radial direction relative to the guide groove of the support block.

(7) Also, preferably, one or both of the concave curved surface of the outer ring and the convex curved surface of the spherical ring are provided with a coating for reducing frictional resistance.
According to this configuration, the position of the spherical ring relative to the outer ring changes smoothly.

(8) Also, preferably, the stationary unit has a first annular sealing member that seals between the spherical ring and the retaining ring, and a second annular sealing member that has smaller frictional resistance than the first annular sealing member and that seals between the spherical ring and the outer ring.
According to the above-mentioned configuration, since the spherical ring and the retaining ring do not slide, there is no need to consider the frictional resistance between them, and a first annular seal member such as a general O-ring is used to seal between them. On the other hand, since the spherical ring and the outer ring slide, a second annular seal member such as an O-ring with low frictional resistance is used to seal between them.

According to the present invention, it is possible to maintain sealing performance even when the inclination angle of the rotating shaft changes while rotating.

FIG. 1 is a cross-sectional view of a mechanical seal according to a first embodiment. FIG. 2 is an enlarged cross-sectional view showing a portion of the outer side of the mechanical seal. FIG. 4 is a cross-sectional view of a mechanical seal according to a second embodiment. FIG. 2 is a cross-sectional view of the mechanical seal showing a state in which a rotating shaft is whirling.

[About mechanical seals in general]
1 is a cross-sectional view of a mechanical seal 10 according to a first embodiment. The mechanical seal 10 is used in a rotating device 7 such as a pump or an agitator. The rotating device 7 includes a rotating shaft 8 and a device casing 9 surrounding the rotating shaft 8. The mechanical seal 10 seals the fluid inside the rotating device 7 between the rotating shaft 8 and the device casing 9. The rotating shaft 8 is rotatably supported by a bearing (not shown) included in the rotating device 7.

Directions in the present disclosure are defined below. The direction along the axis L of the rotating shaft 8 and the direction parallel to the axis L are defined as the "axial direction". With respect to the axial direction, the outside side of the rotating device 7 (left side in FIG. 1) is one axial side, which is referred to as the "outside side". In contrast, the inside side of the rotating device 7 (right side in FIG. 1) is the other axial side, which is referred to as the "inside side". The direction perpendicular to the axis L is defined as the "radial direction". The direction along a circle centered on the axis L of the rotating shaft 8 is defined as the "circumferential direction". In other words, the rotation direction of the rotating shaft 8 is the circumferential direction.

Figure 1 shows a state in which the axis L of the rotating shaft 8 coincides with the axis of the equipment casing 9. As will be described later, the inclination angle of the axis L of the rotating shaft 8 changes as the rotating shaft 8 rotates. Unless otherwise specified, the direction of each configuration of the invention of this disclosure is defined as a state in which the axis L of the rotating shaft 8 coincides with the axis of the equipment casing 9. This coincident state is also referred to as the reference state.

The mechanical seal 10 prevents the sealed fluid (solvent, water, oil, etc.) inside the machine from leaking to the outside. To that end, the mechanical seal 10 has one rotating seal ring 16 and two stationary seal rings 17-1, 17-2. The space between the rotating seal ring 16 and the first stationary seal ring 17-1, and the space between the rotating seal ring 16 and the second stationary seal ring 17-2 each form a seal section that prevents fluid leakage. The mechanical seal 10 according to the first embodiment is a double seal type having two seal sections.

The radially inner side and one axial side of the seal portion where the first seal surface 16a on the outer side of the rotating seal ring 16 faces (contacts) with the seal surface 17a of the first stationary seal ring 17-1 constitutes the outer side region. The radially inner side and the other axial side of the seal portion where the second seal surface 16b on the inner side of the rotating seal ring 16 faces (contacts) with the seal surface 17b of the second stationary seal ring 17-2 constitutes the inner side region. The space on the radially outer side of the seal portion between the rotating seal ring 16 and each of the two stationary seal rings 17-1 and 17-2 constitutes the third region K3, which is filled with a fluid such as quench oil.

The mechanical seal 10 comprises a rotating unit 11 that is rotatable integrally with the rotating shaft 8 and is generally annular or cylindrical, a stationary unit 12 that is generally annular or cylindrical and is provided radially outside the rotating unit 11, and a support unit 13 that is generally annular or cylindrical and supports the stationary unit 12.

[Regarding the rotating unit 11]
The rotating unit 11 has an annular rotating seal ring 16, a sleeve 31, and a stopper ring 32. The rotating seal ring 16 has an annular first seal surface 16a on the outer side and an annular second seal surface 16b on the inner side. The sleeve 31 is a cylindrical member that is fitted onto the rotating shaft 8 and fixed by a set screw 36. The rotating seal ring 16 is attached by fitting onto a part of the sleeve 31.

The stopper ring 32 is a cylindrical member and is fixed to the inside of the sleeve 31. A female thread is formed on the inner circumference of the stopper ring 32, and a male thread is formed on the outer circumference of the sleeve 31. The stopper ring 32 is fixed to the sleeve 31 by screwing them together. The stopper ring 32 sandwiches the rotary seal ring 16 between itself and a part of the sleeve 31 in the axial direction, preventing the rotary seal ring 16 from falling off to the inside of the machine. A resin cushion sheet 51 is interposed between the part of the sleeve 31 and the rotary seal ring 16. The sleeve 31 has a pin 33 that protrudes toward the rotary seal ring 16. A hole is formed on the inner circumference of the rotary seal ring 16. The pin 33 fits into the hole, so that the rotary seal ring 16 rotates integrally with the rotary shaft 8 together with the sleeve 31 and the stopper ring 32. The sleeve 31 and the rotary shaft 8 are sealed by an O-ring 34. The sleeve 31 and the rotary seal ring 16 are sealed by an O-ring 35.

[Regarding the stationary unit 12]
The stationary unit 12 has a first stationary seal ring 17-1 and a second stationary seal ring 17-2 for sealing with the rotating seal ring 16. The first stationary seal ring 17-1 has an annular first seal surface 17a on the inside of the machine. The second stationary seal ring 17-2 has an annular second seal surface 17b on the outside of the machine. In addition to the two stationary seal rings 17-1 and 17-2, the stationary unit 12 has a spherical ring 18, an annular first retaining ring 19-1 that is integral with the spherical ring 18 and holds the first stationary seal ring 17-1, an annular second retaining ring 19-2 that is integral with the spherical ring 18 and holds the second stationary seal ring 17-2, and a bearing block 21 that is integral with the spherical ring 18.

In the embodiment shown in FIG. 1, the spherical ring 18 has a two-part structure. That is, the spherical ring 18 has a first spherical ring 18-1 on the outside of the aircraft and a second spherical ring 18-2 on the inside of the aircraft. The first spherical ring 18-1 and the second spherical ring 18-2 are connected to each other by bolts 22 and become one body. The second spherical ring 18-2 is provided with a flow passage 23 that penetrates in the radial direction to form a part of the third region K3.

The spherical ring 18 has a convex surface 24 on its outer periphery, the shape of which follows an imaginary spherical surface having a center point on the axis of the spherical ring 18 (stationary unit 12). In the reference state, the axis of the spherical ring 18 coincides with the axis L of the rotating shaft 8. The convex surface 24 is in surface contact with a concave surface 61 of the outer ring 60, which will be described later. A recess 25 is provided on part of the convex surface 24, the recess being constituted by a hole that opens radially outward.

The tip 73c of the pin 73 of the first anti-rotation mechanism 71 (see FIG. 2), which will be described later, is housed in the recess 25. In this embodiment, a rolling bearing 29 is attached to the recess 25. The pin 73 is housed on the inner periphery of the rolling bearing 29 in the recess 25. This configuration restricts the rotation of the spherical ring 18 relative to the outer ring 60.

In FIG. 1, the first retaining ring 19-1 is provided on the inner periphery of the first spherical ring 18-1. A groove is formed on the inner periphery of the first retaining ring 19-1, into which the first stationary seal ring 17-1 is tightly fitted and attached. A plurality of connecting bolts 26 are attached to the first spherical ring 18-1 along the circumferential direction. The first retaining ring 19-1 has holes through which the connecting bolts 26 pass. With this configuration, the first retaining ring 19-1 is attached in such a way that it cannot rotate relative to the first spherical ring 18-1 but can be displaced in the axial direction. The gap between the first retaining ring 19-1 and the first spherical ring 18-1 is sealed by an O-ring 38-1.

The second retaining ring 19-2 is provided on the inner periphery of the second spherical ring 18-2. A groove is formed on the inner periphery of the second retaining ring 19-2, and the second stationary seal ring 17-2 is fitted tightly into the groove. A plurality of bottomed holes 27 are provided along the circumferential direction of the second spherical ring 18-2. An elastic member (compression coil spring 28) is provided in the bottomed hole 27. The outer end of the compression coil spring 28 is in contact with the second retaining ring 19-2. The elastic restoring force of the compression coil spring 28 presses the second stationary seal ring 17-2 against the rotating seal ring 16, and the rotating seal ring 16 is pressed against the first stationary seal ring 17-1. When the rotating shaft 8 rotates together with the rotating unit 11, the rotating seal ring 16 slides against the stationary seal rings 17-1 and 17-2. The gap between the second retaining ring 19-2 and the second spherical ring 18-2 is sealed by an O-ring 38-2.

[Regarding bearing block 21]
Fig. 2 is an enlarged cross-sectional view showing a part of the outer side of the mechanical seal 10 shown in Fig. 1. The bearing block 21 has a rolling bearing 43 and a cylindrical bearing case 41 that holds the rolling bearing 43. The bearing case 41 is connected to the outer side of the spherical ring 18 by a bolt 39. Seals 42 that prevent foreign matter from entering are attached to the inner peripheral side of the bearing case 41 and both axial sides of the rolling bearing 43. An O-ring 37 seals the gap between the bearing case 41 and the first spherical ring 18-1.

The rolling bearing 43 has an outer ring 44 and a number of rollers 45 arranged in the circumferential direction, and the rolling bearing 43 in this embodiment is a needle bearing. The outer ring 44 is fitted and fixed in the bearing case 41. The outer ring 44 has an outer raceway 46 on its inner periphery with which the rollers 45 roll and make contact, and a pair of flanges 47, 47 that protrude radially inward on both axial sides of the outer raceway 46. The pair of flanges 47, 47 restrict the position of the rollers 45 in the axial direction (i.e., limit the axial displacement). When the mechanical seal 10 is assembled to the rotating shaft 8, a radial load (pressure) is applied to the rollers 45.

In the embodiment shown in FIG. 2, the rolling bearing 43 does not have an inner ring, and a part of the outer peripheral surface of the sleeve 31 becomes the inner raceway 48 with which the roller 45 rolls. The part of the sleeve 31 that functions as the inner ring does not have a flange on either side of the roller 45 in the axial direction, and has the inner raceway 48 and cylindrical surfaces 49 that extend from the inner raceway 48 on either side in the axial direction. This configuration results in a configuration in which axial slip occurs between the roller 45 and the inner raceway 48. In other words, axial displacement is permitted between the roller 45 and the inner raceway 48.

In this way, the bearing block 21 is interposed between the spherical ring 18 (first spherical ring 18-1) and the rotating unit 11 (sleeve 31). Therefore, when the inclination angle of the rotating shaft 8 and rotating unit 11 changes, the inclination angle of the bearing block 21 also changes to follow that change, and the bearing block 21 tilts the spherical ring 18 at that inclination angle. In other words, the bearing block 21 is connected to the spherical ring 18 by the bolts 39 and is integrated, and causes the spherical ring 18 to follow the inclination of the rotating shaft 8.

Although not shown, the rollers 45 of the rolling bearing 43 may be in rolling contact with a part of the outer circumferential surface of the rotating shaft 8. In this case, the bearing block 21 is interposed between the spherical ring 18 (first spherical ring 18-1) and the rotating shaft 8.
Although not shown, the rolling bearing 43 may have an inner ring with which the roller 45 rolls. In this case, the inner ring is included in the rotating unit 11.
Even in these cases, the bearing block 21 allows the spherical ring 18 to follow the inclination of the rotating shaft 8. Also, axial displacement is permitted between the rollers 45 and the inner raceway surface.

[Regarding the support unit 13]
1, the support unit 13 supports the stationary unit 12. To that end, the support unit 13 has an outer ring 60 and a support block 62 that supports the outer ring 60. The outer ring 60 has a concave surface 61 on its inner periphery that comes into surface contact with the convex surface 24 of the spherical ring 18. The concave surface 61 has a shape that follows an imaginary spherical surface having a center point on the axis of the support unit 13. In the reference state, the axis of the support unit 13 coincides with the axis L of the rotation shaft 8.

In the embodiment shown in FIG. 1, the outer ring 60 has a first outer ring 60-1 on the outboard side that is in surface contact with the convex curved surface 24 of the first spherical ring 18-1, and a second outer ring 60-2 on the inboard side that is in surface contact with the convex curved surface 24 of the second spherical ring 18-2. The first outer ring 60-1 and the second outer ring 60-2 are not connected, and are held independently by guide grooves 65-1 and 65-2 of the support block 62, which will be described later. A part of the third region K3 is formed between the first outer ring 60-1 and the second outer ring 60-2.

As will be explained later, when the rotation shaft 8 changes its inclination angle, the convex surface 24 comes into sliding contact with the concave surface 61. Therefore, the concave surface 61 is provided with a coating 81 to reduce the coefficient of friction. The convex surface 24 may also be provided with the coating 81. In other words, it is sufficient that the coating 81 is provided on one or both of the concave surface 61 and the convex surface 24.

The support block 62 has multiple annular blocks 62a extending from the inside to the outside of the machine, and the multiple annular blocks 62a are connected together by bolts 63. The support block 62 is fixed to the equipment casing 9 by mounting bolts 59. A through hole 64 that constitutes part of the third region K3 is provided in the axial center of the support block 62. Although not shown, a pipe through which a fluid such as quench oil flows is connected to the through hole 64.

A first guide groove 65-1 is provided on the outer side of the support block 62, and a second guide groove 65-2 is provided on the inner side of the support block 62. The first guide groove 65-1 and the second guide groove 65-2 are each formed as a concave circumferential groove that opens radially inward. The first guide groove 65-1 supports the first outer ring 60-1 so as to be displaceable in the radial direction. The second guide groove 65-2 supports the second outer ring 60-2 so as to be displaceable in the radial direction.

The first outer ring 60-1 is in sliding contact with the first guide groove 65-1. The second outer ring 60-2 is in sliding contact with the second guide groove 65-2. Therefore, a coating 80 is provided on the sliding surface of the first outer ring 60-1 against the first guide groove 65-1 to reduce the coefficient of friction. Also, a coating 80 is provided on the sliding surface of the second outer ring 60-2 against the second guide groove 65-2 to reduce the coefficient of friction. As described above, the pressure is higher in the third region K3 than on the inside and outside of the machine. Therefore, as shown in FIG. 1, the coating 80 is provided only on the sliding surface away from the third region K3.

The coating 80 may be provided on the first guide groove 65-1 and the second guide groove 65-2 side. In other words, the coating 80 may be provided on one or both of the guide grooves 65-1, 65-2 and the sliding surfaces of the outer rings 60-1, 60-2 that come into sliding contact with the guide grooves 65-1, 65-2.

The gap between the first outer ring 60-1 and the first guide groove 65-1 is sealed by an O-ring 66-1. The gap between the first outer ring 60-1 and the first spherical ring 18-1 is sealed by an O-ring 67-1. The gap between the second outer ring 60-2 and the second guide groove 65-2 is sealed by an O-ring 66-2. The gap between the second outer ring 60-2 and the second spherical ring 18-2 is sealed by an O-ring 67-2.

[Regarding the anti-rotation mechanism of the stationary unit 12]
When the rotating shaft 8 rotates together with the rotating unit 11, the rotating seal ring 16 comes into sliding contact (sliding) with each of the stationary seal rings 17-1, 17-2. As a result, a rotational force acts on the stationary unit 12 having the stationary seal rings 17-1, 17-2. Therefore, the mechanical seal 10 is provided with a rotation prevention mechanism that restricts the rotation of the stationary unit 12.

Specifically, in FIG. 2, the mechanical seal 10 includes a first anti-rotation mechanism 71 that restricts the rotation of the spherical ring 18 (first spherical ring 18-1) relative to the outer ring 60 (first outer ring 60-1). The mechanical seal 10 further includes a second anti-rotation mechanism 72 that restricts the rotation of the outer ring 60 (first outer ring 60-1) relative to the support block 62.

As the first anti-rotation mechanism 71, the outer ring 60 has a pin (first pin) 73 that protrudes toward the spherical ring 18. The pin 73 has a body portion 73a with a male thread on the outer periphery and a shaft portion 73b that protrudes from the body portion 73a. The male thread of the body portion 73a is attached to a threaded hole formed in the outer ring 60. The shaft portion 73b has a spherical tip portion 73c.

As described above, the spherical ring 18 is provided with a recess 25. The recess 25 is formed of a hole having an inner diameter larger than the diameter of the spherical tip 73c. The recess 25 is in a state in which the tip 73c of the pin 73 is accommodated. In this embodiment, a rolling bearing 29 is attached to the recess 25. The rolling bearing 29 has an inner diameter larger than the diameter of the spherical tip 73c, and the rolling bearing 29 is in a state in which the tip 73c of the pin 73 is accommodated. The tip 73c of the pin 73 can contact the inner circumferential surface of the rolling bearing 29. The rolling bearing 29 may be omitted, in which case the tip 73c of the pin 73 can contact the inner circumferential surface of the recess 25. The pin 73 contacts the rolling bearing 29 attached to the recess 25 or the recess 25, thereby restricting the rotation of the spherical ring 18 relative to the outer ring 60.

As the second anti-rotation mechanism 72, the outer ring 60 has a second pin 74 that protrudes toward the support block 62. The pin 74 has a body portion 74a with a male thread on its outer periphery and a shaft portion 74b that protrudes from the body portion 74a. The male thread of the body portion 74a is attached to a threaded hole formed in the outer ring 60. A rolling bearing 75 is attached to the tip portion 74c of the shaft portion 74b.

As described above, the support block 62 has a plurality of annular blocks 62a, of which the annular block 62a on the outer side of the machine functions as a cover member that closes the first guide groove 65-1 from the outer side of the machine. The second recess 76 is provided in the annular block 62a on the outer side of the machine. The recess 76 is formed of a hole having an inner diameter larger than the outer diameter of the tip 74c of the pin 74 and the outer diameter of the rolling bearing 75. The recess 76 is in a state in which the tip 74c of the pin 74 and the rolling bearing 75 are accommodated. The rolling bearing 75 attached to the tip 74c of the pin 74 can contact the inner circumferential surface of the recess 76. The rolling bearing 75 may be omitted, in which case the tip 74c of the pin 74 can contact the inner circumferential surface of the recess 76. The pin 74 or the rolling bearing 75 attached to the pin 74 contacts the recess 25, thereby restricting the rotation of the outer ring 60 relative to the support block 62.

In addition, in the first anti-rotation mechanism 71, a rolling bearing may be provided at the tip of the pin 73, as in the second anti-rotation mechanism 72, and in the second anti-rotation mechanism 72, a rolling bearing may be provided in the second recess 76, as in the first anti-rotation mechanism 71.

[Regarding the mechanical seal 10 of the first embodiment]
1 is a double seal type having one rotating seal ring 16 and two stationary seal rings 17-1, 17-2. In accordance with the two stationary seal rings, the spherical ring 18 has a first spherical ring 18-1 on the outside and a second spherical ring 18-2 on the inside, and the outer ring 60 has a first outer ring 60-1 on the outside and a second outer ring 60-2 on the inside.

[Regarding the mechanical seal 10 of the second embodiment]

Figure 3 is a cross-sectional view of the mechanical seal 10 according to the second embodiment. The mechanical seal 10 shown in Figure 3 is a single seal type having one rotating seal ring 16 and one stationary seal ring 17-1. In accordance with the single stationary seal ring 17-1, the mechanical seal 10 has one first spherical ring 18-1 and one outer ring 60-1 on the outside of the machine. Compared to the first embodiment shown in Figure 1, the second embodiment shown in Figure 3 omits the second spherical ring 18-2 on the inside of the machine, the second outer ring 60-2 on the inside of the machine, and the third region K3, and is otherwise almost the same. The same reference numerals are used in the second embodiment shown in Figure 3 for the same configuration as in the first embodiment. In the second embodiment, a compression coil spring that applies an axial biasing force between the stationary seal ring 17-1 and the rotating seal ring 16 is provided in the retaining ring 19-1, although not shown.

[Regarding the mechanical seal 10 of each embodiment]
As described above, the mechanical seal 10 of each of the first and second embodiments includes the rotating unit 11 having the rotating seal ring 16 and capable of rotating integrally with the rotating shaft 8, the stationary unit 12 having the stationary seal ring 17-1 (17-2) for sealing with the rotating seal ring 16, and the support unit 13 supporting the stationary unit 12. The support unit 13 has an outer ring 60, and the outer ring 60 has on its inner circumference a concave curved surface 61 shaped along a virtual spherical surface having a center point on the axis of the support unit 13.

The stationary unit 12 has a spherical ring 18 whose rotation relative to the outer ring 60 is restricted, a retaining ring 19-1 (19-2) that is integral with the spherical ring 18, and a bearing block 21 that is integral with the spherical ring 18. The spherical ring 18 has a convex surface 24 on its outer periphery that is in surface contact with the concave surface 61. The retaining ring 19-1 (19-2) holds the stationary seal ring 17-1 (17-2). The bearing block 21 is interposed between the spherical ring 18 and the rotating unit 11 (or the rotating shaft 8) and causes the spherical ring 18 to follow the inclination of the rotating shaft 8.

Figures 1 and 3 show a reference state in which the axis L of the rotating shaft 8 coincides with the axis of the equipment casing 9. Figure 4 shows a state in which the rotating shaft 8 is whirling, in which the axis L of the rotating shaft 8 is tilted from the reference state, and furthermore, the axis L is displaced (eccentric) in the radial direction. In Figure 4, the tilt angle of the axis L from the reference state is indicated by "θ", and the amount of eccentricity of the axis L from the reference state is indicated by "E". When the axis L of the rotating shaft 8 reaches the tilt angle θ, the tilt angle of the axis of the rotating seal ring 16 included in the rotating unit 11 also becomes "θ".

According to the mechanical seal 10 of each of the above-described embodiments, when the inclination angle θ of the axis L of the rotating shaft 8 changes while the rotating shaft 8 rotates, the spherical ring 18 follows the inclination angle θ by the bearing block 21, and the inclination angle of the axis of the spherical ring 18 also changes. Even if the inclination angle of the spherical ring 18 changes, the outer ring 60 supports the spherical ring 18 by allowing the change via the concave curved surface 61. In other words, the inclination angle of the spherical ring 18 becomes "θ".
In accordance with the change in the inclination angle of the spherical ring 18, the inclination angle of the stationary seal ring 17-1 (17-2) held by the retaining ring 19-1 (19-2) which is integral with the spherical ring 18 also changes. In other words, the inclination angle of the stationary seal ring 17-1 (17-2) becomes "θ".
As a result, even if the inclination angle θ of the rotating shaft 8 changes while rotating, there is no change in the relative position between the rotating seal ring 16 and the stationary seal ring 17-1 (17-2), and sealing performance is maintained.

As described above, when the rotating shaft 8 whirls, the rotating shaft 8 changes the inclination angle θ and is displaced (eccentric) in the radial direction as shown in FIG.
In the mechanical seal 10 of each of the above embodiments, the support block 62 of the support unit 13 is provided with a guide groove 65-1 (65-2) that supports the outer ring 60 so that it can be displaced in the radial direction. Therefore, even if the rotating shaft 8 changes the inclination angle θ and displaces in the radial direction, the outer ring 60 that supports the spherical ring 18 displaces in the radial direction, and the stationary unit 12 follows the rotating shaft 8. As a result, there is no change in the relative position between the rotating seal ring 16 and the stationary seal ring 17-1 (17-2), and the sealing performance is maintained.

In the example shown in FIG. 4, the rotating shaft 8 is tilted so that the inclination angle θ changes with a position on the outside of the mechanical seal 10 as the base point. In this case, an axial displacement component occurs between the rotating shaft 8 and the rotating unit 11 and the stationary unit 12. Therefore, in each of the above embodiments, the bearing block 21 for making the stationary unit 12 follow the rotating unit 11 has a rolling bearing 43 and a bearing case 41 that holds the rolling bearing 43 and is connected to the spherical ring 18. The rolling bearing 43 has a plurality of rollers 45 and is configured to allow axial displacement between the rollers 45 and the raceway surface (inner raceway surface 48) with which the rollers 45 roll and make contact.

As an example of the configuration for this purpose, referring to FIG. 2, as described above, the outer ring 44 of the rolling bearing 43 has flanges 47 on both axial sides of the roller 45. In contrast, the sleeve 31, which serves as the inner ring, does not have flanges on both axial sides of the roller 45. This results in a configuration in which axial slip occurs between the roller 45 and the inner raceway surface 48, allowing axial displacement between the roller 45 and the inner raceway surface 48.

Therefore, the axial displacement component occurring between the rotating shaft 8 and the rotating unit 11 and the stationary unit 12 is absorbed by the rolling bearing 43. As a result, the rotating shaft 8 follows the mechanical seal 10 smoothly. Note that although the rollers 45 have been described as allowing axial slippage between themselves and the inner raceway surface 48, they may also be configured to allow axial slippage on the outer ring 44 side.

As described above, the mechanical seal 10 in each of the above-described embodiments includes a first anti-rotation mechanism 71 that restricts the rotation of the spherical ring 18 relative to the outer ring 60. Even if the rotating shaft 8 rotates together with the rotating unit 11 and the stationary seal ring 17-1 (17-2) receives a rotational force from the rotating seal ring 16, causing the spherical ring 18 to rotate, the tip 73c of the pin 73 of the outer ring 60 comes into contact with the inner surface of the recess 25 (the rolling bearing 29 attached to the recess 25) provided in the spherical ring 18, and the spherical ring 18 is prevented from rotating.
Since the recess 25 (the space on the inner periphery side of the rolling bearing 29) is larger than the tip 73c of the pin 73, the change in the inclination angle of the spherical ring 18 relative to the outer ring 60 is not hindered.

Furthermore, as described above, the mechanical seal 10 of each of the above-described embodiments includes the second anti-rotation mechanism 72 that restricts the rotation of the outer ring 60 relative to the support block 62. Even if the rotating shaft 8 rotates together with the rotating unit 11, the stationary seal ring 17-1 (17-2) receives a rotational force from the rotating seal ring 16, and the outer ring 60 attempts to rotate along with the spherical ring 18 of the stationary unit 12, the tip (rolling bearing 75) of the second pin 74 of the outer ring 60 comes into contact with the inner surface of the second recess 76 provided in the support block 62, and the outer ring 60 is prevented from rotating.
Since the second recess 76 is larger than the tip (rolling bearing 75 ) of the second pin 74 , radial displacement of the outer ring 60 relative to the support block 62 is not hindered.

The first anti-rotation mechanism 71 and the second anti-rotation mechanism 72 are provided with rolling bearings 29, 75. The first pin 73 contacts the inner surface of the recess 25 at any position, and the second pin 74 contacts the second recess 76 at any position. The rolling bearings 29, 75 smoothly change the relative positions between the pins 73, 74 and the mating member, regardless of the position at which the pins 73, 74 contact the mating member, and the pins are placed in appropriate positions relative to each other, restricting rotation.

As described above, the coating 81 for reducing frictional resistance is provided on the concave curved surface 61 of the outer ring 60. This allows the spherical ring 18 to smoothly change its position relative to the outer ring 60.
As described above, the coating 80 for reducing the coefficient of friction is provided on the sliding surface of the outer ring 60 that comes into sliding contact with the guide groove 65-1 (65-2), which allows smooth radial displacement of the outer ring 60 relative to the guide groove 65-1 (65-2).

Furthermore, in each of the above embodiments, the mechanical seal 10 has multiple O-rings as described above, but multiple types (two types) of O-rings are used. Of the multiple types of O-rings, one is a first annular seal member (O-ring) made of highly versatile rubber, and the other is a second annular seal member (O-ring) that has lower friction resistance than the first annular seal member (O-ring). Note that the second annular seal member is generally more expensive.

Specifically, the O-ring 67-1 (67-2) that seals between the spherical ring 18 and the outer ring 60 corresponds to the second annular seal member. Also, the O-ring 66-1 (66-2, 66-2) that seals between the outer ring 60 and the guide groove 65-1 (65-2) corresponds to the second annular seal member. In other words, the O-ring used on the surface that slides when the rotating shaft 8 changes the inclination angle θ or is displaced in the radial direction corresponds to the second annular seal member.
On the other hand, an O-ring used on a surface that does not slide even when the rotating shaft 8 changes the inclination angle θ or is displaced in the radial direction corresponds to the first annular seal member. For example, the O-ring 38-1 (38-2) that seals between the spherical ring 18 and the retaining ring 19-1 (19-2) corresponds to the first annular seal member.

In this way, by using two types of O-rings, the following effects can be achieved.
Even if the rotating shaft 8 changes the inclination angle θ or is displaced in the radial direction, for example, the spherical ring 18 and the retaining ring 19-1 (19-2) do not slide, so there is no need to consider the frictional resistance between them, and a first annular seal member such as a general O-ring is used to seal between them. In contrast, the spherical ring 18 and the outer ring 60 slide, and the outer ring 60 slides between the guide groove 65-1 (65-2), so a second annular seal member such as an O-ring with low frictional resistance is used to seal between them. This makes it possible, for example, for the spherical ring 18 to smoothly change its position relative to the outer ring 60, making it easier for the stationary unit 12 to follow the inclination of the rotating shaft 8.

As described above, the mechanical seal 10 according to each of the above embodiments makes it possible to maintain the sealing performance of the rotating seal ring 16 and the stationary seal ring 17-1 (17-2) even if the rotating shaft 8 changes its position.

〔others〕
In the above embodiment, the rotating unit 11 may have a form other than that shown in the figures as long as it has a rotating seal ring 16, and the stationary unit 12 may have a form other than that shown in the figures as long as it has a stationary seal ring 17.

The above-described embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above-described embodiment, and includes all modifications within the scope of equivalence to the configurations described in the claims.

Reference Signs List 8 Rotating shaft 10 Mechanical seal 11 Rotating unit 12 Stationary unit 13 Support unit 16 Rotating seal ring 17-1, 17-2 Stationary seal ring 18 Spherical ring 18-1 First spherical ring 18-2 Second spherical ring 19-1 First retaining ring 19-2 Second retaining ring 21 Bearing block 24 Convex surface 25 Convex portion 37 O-ring (first annular seal member)
38-1 O-ring (first annular seal member)
38-2 O-ring (first annular seal member)
41 Bearing case 43 Rolling bearing 45 Roller 48 Inner raceway surface (raceway surface)
60 Outer ring 60-1 First outer ring 60-2 Second outer ring 61 Concave surface 62 Support block 65-1 First guide groove 65-2 Second guide groove 66-1 O-ring (second annular seal member)
66-2 O-ring (second annular seal member)
67-1 O-ring (second annular seal member)
67-2 O-ring (second annular seal member)
71 Anti-rotation mechanism 72 Second anti-rotation mechanism 73 Pin 73c Tip 74 Second pin 74c Tip 76 Second recess 80 Coating 81 Coating L Axis

Claims (6)

a rotating unit having a rotating seal ring and capable of rotating integrally with a rotating shaft;
a stationary unit having a stationary seal ring for sealing against the rotary seal ring;
A support unit for supporting the stationary unit;
Equipped with
The support unit has an outer ring having an inner periphery with a concave curved surface shaped along a virtual spherical surface having a center point on an axis line of the support unit,
The stationary unit comprises:
a spherical ring whose rotation with respect to the outer ring is restricted and which has a convex curved surface on its outer periphery that is in surface contact with the concave curved surface;
a retaining ring integral with the spherical ring and retaining the stationary seal ring;
a bearing block that is integral with the spherical ring and is interposed between the spherical ring and the rotation shaft or the rotation unit so that the spherical ring follows the inclination of the rotation shaft;
having
the support unit includes a support block having a guide groove for supporting the outer ring so as to be displaceable in a radial direction,
The bearing block is
a rolling bearing having a plurality of rollers and allowing axial displacement between the rollers and a raceway surface with which the rollers roll and contact;
A bearing case that holds the rolling bearing and is connected to the spherical ring.
Mechanical seal. The outer ring has a pin protruding toward the spherical ring as a rotation prevention mechanism for restricting rotation of the spherical ring relative to the outer ring,
2. The mechanical seal according to claim 1 , wherein said spherical ring is provided with a recess for receiving a tip of said pin. the outer ring has a second pin protruding toward the support block as a second anti-rotation mechanism for restricting rotation of the outer ring relative to the support block,
The mechanical seal of claim 1 , wherein the support block is provided with a second recess for receiving a tip of the second pin. 4. The mechanical seal according to claim 1 , wherein a coating for reducing a coefficient of friction is provided on one or both of the guide groove and the sliding surface of the outer ring that comes into sliding contact with the guide groove. 5. The mechanical seal according to claim 1 , wherein a coating is provided on one or both of the concave curved surface of the outer ring and the convex curved surface of the spherical ring to reduce frictional resistance. The stationary unit comprises:
a first annular seal member that seals between the spherical ring and the retaining ring;
a second annular seal member that has a smaller friction resistance than the first annular seal member and seals between the spherical ring and the outer ring;
The mechanical seal according to any one of claims 1 to 5 , having the following structure:

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