JP2020190313A - Rotation preventive mechanism - Google Patents

Abstract

To provide a rotation preventive mechanism for a slide component developing high durability by suppressing the occurrence of wear and breakage.SOLUTION: The rotation preventive mechanism is used for a slide component 1 where a rotational slide ring 4 to be rotated in the peripheral direction together with a rotation side element R mounted to a rotary shaft 2 and a stationary slide ring 6 fixed to a stationary side element S slide against each other, to prevent the rotation of the rotational slide ring 4 relative to the rotation side element R or the stationary slide ring 6 relative to the stationary side element S. The rotation preventive mechanism includes a recessed part 6b, and a fitted part 17 fitted into the recessed part 6b. In the inner face of the recessed part 6b or in the outer face of the fitted part 17, dimple parts 14 are provided having recessed shapes.SELECTED DRAWING: Figure 4

Description

The present invention relates to a detent mechanism applied to a sliding component such as a mechanical seal that seals a rotating shaft.

The sliding component is used by being mounted between the housing of the fluid device and the rotating shaft arranged so as to penetrate the housing, and is fixed to a stationary side element composed of the housing or the like. The sliding surface of the sliding ring and the sliding surface of the rotating sliding ring that rotates together with the rotating side element such as the rotating shaft are brought into sliding contact with each other in the circumferential direction to prevent leakage of the sealed fluid.

In such a sliding component, a drive pin projecting in the axial direction from a rotating side element such as a collar fixed to the rotating shaft is fitted into a recess formed on the back surface of the rotating sliding ring. The rotating sliding ring is prevented from rotating with respect to the element on the rotating side, and has a structure that rotates together with the rotating shaft. Similarly, a knock pin projecting from a stationary side element such as a housing is fitted into a recess on the back surface of the stationary sliding ring, so that the stationary sliding ring is prevented from rotating with respect to the stationary element and maintains a stationary state. It has a structure. That is, the detent mechanism composed of the recesses on the back surface of these sliding rings and the fitting portions of the detent members such as drive pins and knock pins fitted in the recesses slides with each other via the sliding surface. It functions to regulate the rotation of the sliding ring by receiving the sliding torque of the driving ring (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2017-207147 (Page 2, Fig. 1)

However, in the detent mechanism applied to such sliding parts, due to the rotational sliding between the sliding rings, it occurs at the contact point between the inner surface of the recess on the back surface side of the sliding ring and the outer surface of the fitting portion. Due to the vibration and the like, the fitting portion and the recess are liable to be worn or damaged, and the durability of the detent mechanism is poor.

The present invention has been made in view of such problems, and an object of the present invention is to provide a detent mechanism for sliding parts having high durability by suppressing the occurrence of wear and breakage.

In order to solve the above problems, the detent mechanism of the present invention is used.
The rotating sliding ring is used for a sliding component in which a rotating sliding ring that rotates in the circumferential direction together with a rotating side element attached to the rotating shaft and a stationary sliding ring fixed to the stationary side element slide relative to each other. A detent mechanism that detents the rotating side element or detents the resting sliding ring from the resting side element.
The detent mechanism is composed of a recess and a fitting portion fitted into the recess, and a concave dimple portion is provided on the inner surface of the recess or the outer surface of the fitting portion.
According to this, the surrounding fluid is introduced into the dimple portion provided on the inner surface of the recess or the outer surface of the fitting portion fitted in the recess, so that the fluid is introduced between the outer surface of the fitting portion and the inner surface of the recess. Since a fluid film can be formed, the contact point between the fitting portion and the recess can be brought into a good lubrication state by this fluid film, and the occurrence of wear and breakage of the detent mechanism can be suppressed.

The dimple portion extends from a contact region between the outer surface of the fitting portion and the inner surface of the recess and a non-contact region excluding the contact region.
According to this, the fluid introduced from the non-contact region between the inner surface of the recess and the outer surface of the fitting portion can be easily discharged toward the contact region, and a fluid film can be reliably formed in this contact region.

The dimple portion extends in the axial direction of the sliding ring.
According to this, it is easy to introduce the fluid to the entire surface of the dimple portion by utilizing the vibration acting on the sliding ring in the axial direction.

The dimple portion is formed in an elliptical shape having a major axis in the axial direction of the sliding ring.
According to this, it is easy to introduce the fluid to the end of the dimple formed in an elliptical shape.

A plurality of dimple portions are provided on the outer surface of the fitting portion.
According to this, the lubricity in the recess can be improved.

A dimple-forming region having the plurality of dimple portions is formed over a contact region between the outer surface of the fitting portion and the inner surface of the recess and a non-contact region excluding the contact region.
According to this, the fluid accumulated in the non-contact region between the inner surface of the recess and the outer surface of the fitting portion can be introduced into the contact region.

A communication groove is provided to communicate the plurality of dimple portions with each other.
According to this, the fluid is always supplied to each dimple portion, and the lubricity can be maintained.

The plurality of dimple portions are separated from each other at the same pitch.
According to this, a homogeneous fluid film can be formed in the recess.

The plurality of dimple portions are provided in the same shape.
According to this, a homogeneous fluid film can be formed in the recess.

It is sectional drawing which shows the structure of the mechanical seal of the Example of this invention. It is sectional drawing of AA of FIG. It is a figure which shows the mode in which the sealed fluid and the barrier liquid are filled in the mechanical seal of Example 1. It is sectional drawing of the main part which shows the fitting mode of the detent mechanism of Example 1, and shows the mode in which a fluid film is formed. It is a perspective view which shows the fitting mode of the detent mechanism in the modification of Example 1. FIG. It is a perspective view which shows the fitting mode of the detent mechanism of Example 2, and shows the mode in which a fluid film is formed. It is sectional drawing of the main part which shows the fitting mode of the detent mechanism in the modification 1 of the second embodiment. It is sectional drawing of the main part which shows the fitting mode of the detent mechanism in the modification 2 of the second embodiment.

A mode for carrying out the detent mechanism according to the present invention will be described below based on examples.

The detent mechanism for mechanical sealing according to the first embodiment will be described with reference to FIGS. 1 to 5. Hereinafter, the right side of the paper surface of FIG. 1 will be described as the outside of the machine, which is the atmospheric region, and the left side of the paper surface will be described as the inside of the machine.

As shown in FIG. 1, the mechanical seal 1 as a sliding component of the first embodiment includes a rotary seal ring 4 as a rotary sliding ring that rotates together with a rotary shaft 2, and a coil spring arranged on the seal cover 10. It is a static mechanical seal 1 including a static sealing ring 6 as a static sliding ring pressed by a retainer 18 urged by 8. Further, the mechanical seal 1 of this embodiment is fixed to the rotary shaft 2 with an annular static sealing ring 6 or 6'that is prevented from rotating with respect to the seal cover 10 on the outside of the machine and the seal cover 10'on the inside of the machine. The rotary sealing rings 4 and 4'that are prevented from rotating with respect to the sleeve 3 are tandem type mechanical seals 1 that are arranged so as to face the same direction in the axial direction. The mechanical seal 1 is stationary having a static sealing ring 6, 6'which is detented to an annular case 9 fixed to the seal covers 10, 10'via knock pins 7, 7'as detent pins. It is mainly composed of a side element S and a rotating side element R having a rotating sealing ring 4, 4'that rotates together with the rotating shaft 2.

The rotating side element R and the stationary side element S will be described in more detail with reference to FIG. As shown in FIG. 1, the rotating side element R includes a sleeve 3 fixed to the rotating shaft 2, rotating ring holding members 20, 20'fixed to the sleeve 3, and the rotating ring holding member 20. , 20', drive pins 5, 5'as detent pins extending substantially horizontally to the outside of the machine, and rotational force transmitted from the rotation shaft 2 via the drive pins 5, 5'rotate in the circumferential direction. It is mainly composed of an annular rotary sealing ring 4, 4'.

The stationary side elements S are arranged so that the seal covers 10 and 10'are adjacent to each other in the axial direction, and the connecting bolts 11 are inserted through the seal covers 10 and 10'in the axial direction and fixed to the device main body M. Further, the seal covers 10 and 10'are statically sealed by sliding contact with the coil springs 8 and 8'that urge the retainers 18 and 18' from the back side in the axial direction and the rotary sealing rings 4 and 4'. Knock pins 7, 7'to prevent the rings 6, 6'from rotating are attached. The knock pins 7, 7'are engaged in the axial direction from the back side of the cases 9, 9', and the cases 9, 9'are in the seal covers 10, 10', and the static sealing ring 6 is provided. , 6'is fitted inward on the outer diameter side.

Further, as shown in FIG. 1, the seal cover 10 has a barrier liquid inflow port 19 and a quenching liquid inflow port 49 formed in the radial direction, and the seal cover 10'has a flushing liquid formed in the radial direction. It has an inflow port 39 and a barrier liquid outflow port 29. The barrier liquid B flowing in from the barrier liquid inflow port 19 passes through the communication passage L1 communicating in the radial direction by the case 9, flows into the space Z described later, and flows from the space Z to the barrier liquid outflow port 29. It has become like. Further, the fluid pressure of the barrier liquid B is controlled so as to be higher than that of the sealed fluid H. Since the mechanical seal 1 of this embodiment is a tandem type as described above and has a configuration similarly arranged in the axial direction, the following are the static sealing ring 6 and the rotary sealing ring 4 on the outside of the machine. The configuration will be described, and the description of the internal configuration will be omitted.

As shown in FIG. 1, the seal cover 10 is formed in an axially axially annular shape, and a plurality of coil springs 8 are evenly arranged in the circumferential direction so as to urge the retainer 18 in the axial direction. ing. By arranging the coil springs 8 in a plurality of equal arrangements in this way, the retainer 18 transmits the urging force toward the rotary sealing ring 4 in the axial direction with the uniform surface pressure on the back surface 6a of the static sealing ring 6. It is configured to do. Further, the seal cover 10 is similarly formed with holes 10a on the outer peripheral side of the coil springs 8 evenly arranged in the circumferential direction, and the knock pins 7 described later are formed in the holes 10a. The press-fitting portion 27 of the above is press-fitted and fixed.

Next, the case 9 will be described in detail. As shown in FIG. 2, the case 9 has a tubular portion 90 formed in a tubular shape of an axially-viewing ring and a columnar fitting portion extending axially from the tubular portion 90 so as to project toward the inner diameter side. It is mainly formed from the protruding portion 91 of the above and the communication passage L1 formed through the tubular portion 90 in the radial direction. The protruding portion 91 is arranged in the same phase as the communication passage L1, that is, at a position facing the circumferential direction and the radial direction. The projecting portion 91 is formed in a prismatic shape composed of a side wall portion 91a formed of a pair of planes arranged facing the circumferential direction and a bottom portion 91b formed of a plane facing the inner diameter direction, and the side wall portion 91a is formed. Is formed with a plurality of dimple portions 14 which are recesses recessed from the surface of the side wall portion 91a having an elliptical side view and a curved bottom portion. Further, a rectangular recess 6d is formed on the outer peripheral surface 6c of the static sealing ring 6 in the axial direction, and the protrusion 91 of the case 9 described above is formed in a large shape so as to be loosely fitted. .. As a result, the protruding portion 91 of the case 9 is inserted into the recess 6d of the static sealing ring 6 from the radial direction or the axial direction and is fitted in the circumferential direction, and is statically sealed in sliding contact with the rotary sealing ring 4. It is possible to prevent the ring 6 from rotating. That is, a detent mechanism is formed by the recess 6d and the protrusion 91.

Next, with reference to FIG. 3, a region occupied by the sealed fluid H, the barrier liquid B as the sealed liquid, and the air A on the leak side during the operation of the mechanical seal 1 of this embodiment will be described. As shown in FIG. 3, the fluid H to be sealed is sealed by the sliding portion E'between the rotary sealing ring 4'and the static sealing ring 6'on the left side of the paper surface inside the machine. Atmosphere A is partitioned by a sliding portion E of a rotary sealing ring 4 and a static sealing ring 6 on the right side of the paper surface on the outside of the machine. Further, in the space Z formed between the sliding portion E'between the rotary sealing ring 4'and the static sealing ring 6'and the sliding portion E between the rotary sealing ring 4 and the static sealing ring 6, The barrier liquid B flowing in from the barrier liquid inflow port 19 is sealed.

Further, the barrier liquid B flowing in from the barrier liquid inflow port 19 has a sliding portion E between the rotary sealing ring 4 and the static sealing ring 6 and a sliding portion E between the rotary sealing ring 4'and the static sealing ring 6'. The space Z formed from the'and the seal covers 10 and 10'is filled and flows out from the barrier liquid outlet 29. Further, since the barrier liquid B is controlled to have a higher pressure than the sealed fluid H, the sealed fluid H flows into the space Z side even if an abnormality occurs due to a sliding defect of the sliding portion E'. It is configured to keep things down.

With reference to FIG. 4, the fitting mode of the case 9 and the static sealing ring 6 when the mechanical seal 1 of this embodiment is in operation will be described in detail. When the rotary sealing ring 4 facing the static sealing ring 6 urged by the coil spring 8 via the retainer 18 (see FIG. 1) rotates in the circumferential direction, it is loosely fitted in the recess 6d of the static sealing ring 6. The side wall portion 91a of the fitted protruding portion 91 abuts on one inner wall surface 6e of the recess 6d in a circumferential direction, thereby restricting the rotation of the static sealing ring 6. A plurality of dimple portions 14 are formed in the side wall portion 91a of the projecting portion 91 of the case 9 in a major axis in the axial direction, and are spaced apart from each other at a predetermined pitch in the radial direction and the axial direction and arranged in a matrix. Has been done. By doing so, the barrier liquid B can be retained in the dimple portion 14, and a uniform fluid film F is formed between the side wall portion 91a of the protrusion 91 and one inner wall surface 6e of the recess 6d. It has become. For the case 9'and the static sealing ring 6', the sealed fluid H is introduced into the recess 6d'.

As shown in FIG. 5A, the dimples formed in a plane are composed of the dimple portion 14 of the side wall portion 91a of the protruding portion 91 and the flat land portion 15 formed in the gap between the dimple portions 14. The formation region D extends widely to both ends in the axial direction. That is, the dimple forming region D extends over the contact region S1 between the side wall portion 91a and the inner wall surface 6e of the recess 6d and the non-contact region S2 between the side wall portion 91a and the inner wall surface 6e of the recess 6d, and is a barrier liquid. The barrier liquid B flowing in from the inflow port 19 is easily introduced from the non-contact region S2 toward the contact region S1. Therefore, the barrier liquid B can be introduced to the inner part of the concave portion 6d in the axial direction and the radial direction to obtain the fluid film F in a wider region.

Further, as shown in FIG. 5A, the dimple portion 14 has an elliptical shape having a major axis in the axial direction, and is in contact with the dimple portion 14 due to slight vibration due to sliding between the rotary sealing ring 4 and the static sealing ring 6. The fluid stored in the dimple portion 14a formed in the non-contact region S2 near the region S1 is easily discharged to the contact region S1 side. Further, as shown in FIG. 5B, the protruding portion 91 is arranged on the inner wall surface 6e of the recess 6d so as to cross a part of the dimple portions 14b among the plurality of dimple portions 14. May be good.

Here, as shown in FIG. 6, as a modification of the plurality of dimple portions 14 formed in the above-mentioned protruding portion 91, a plurality of dimple portions 24 are formed on the inner wall surface 6e of the recess 6d of the static sealing ring 6. You may. Further, by forming a plurality of dimple portions 24 over both ends of the inner wall surface 6e, it is easy to introduce a fluid.

As described above, as described in the first embodiment and the modified example, the rotary sealing ring 4 that rotates in the circumferential direction together with the rotating side element R attached to the rotating shaft 2 and the static sealing ring 6 fixed to the stationary side element S are A detent mechanism used for sliding parts that slide relative to each other to prevent the rotary sealing ring 6 from rotating with respect to the rotating side element R or the static sealing ring 6 from rotating with respect to the stationary side element S. The mechanism is composed of a recess 6d formed on the back surface of the static sealing ring 6 and a protruding portion 91 of the case 9 fitted in the recess 6d, and is formed on the inner surface of the recess 6d or the outer surface of the protruding portion 91. Since the concave dimple portion 14 is provided, the surrounding fluid is introduced into the dimple portion 14 provided on the inner surface of the concave portion 6d or the outer surface of the protruding portion 91 fitted in the concave portion. Since a fluid film F can be formed between the outer surface of the protruding portion 91 and the inner surface of the recess 6d, the fluid film F keeps the contact point between the protruding portion 91 and the recess 6d in a good lubrication state to prevent rotation. It is possible to suppress the occurrence of wear and tear.

Further, as shown in FIG. 5B, the dimple portion 14b extends from the contact region S1 between the outer surface of the protruding portion 91 and the inner surface of the recess 6d and the non-contact region S2 excluding the contact region S1. Therefore, the fluid introduced from the non-contact region S2 between the inner surface of the recess 6d and the outer surface of the protrusion 91 can be easily discharged toward the contact region S1, and the fluid film F can be reliably generated in the contact region S1.

Further, since the dimple portion 14 extends in the axial direction of the static sealing ring 6 as a sliding ring, the vibration acting on the static sealing ring 6 in the axial direction is utilized to cover the entire surface of the dimple portion 14. Easy to introduce fluid.

Further, since the dimple portion 14 is formed in an elliptical shape having a major axis in the axial direction of the static sealing ring 6 as a sliding ring, it is easy to introduce the fluid to the end portion of the dimple formed in the elliptical shape.

Further, since a plurality of dimple portions 14 are provided on the side wall portion 91a of the protruding portion 91, the lubricity in the recess 6d can be improved.

Further, since the plurality of dimple portions 14 are separated from each other at the same pitch, a homogeneous fluid film F can be formed in the recess 6d.

Further, since the plurality of dimple portions 14 are provided in the same shape, a homogeneous fluid film F can be generated in the recess 6d.

Further, a dimple forming region D having a plurality of dimple portions 14 is formed over the contact region S1 between the outer surface of the protruding portion 91 and the inner surface of the recess 6d and the non-contact region S2 excluding the contact region S1. Therefore, the fluid accumulated in the non-contact region S2 between the inner surface of the recess 6d and the outer surface of the fitting portion can be introduced into the contact region S1.

Next, the detent mechanism for mechanical sealing according to the second embodiment will be described with reference to FIGS. 7 and 8. The same components as those shown in the above embodiment are designated by the same reference numerals, and duplicate description will be omitted.

The detent mechanism for mechanical sealing in the second embodiment will be described. As shown in FIG. 7, in this embodiment, the retainer 18 is omitted and the coil spring 8 is urged in contact with the back surface of the static sealing ring 6 in the radial direction and on the back surface 6a of the static sealing ring 6. A notch 6b notched in a rectangular shape is formed, and a horizontally extending knock pin 7A press-fitted into the hole 10b formed on the side surface of the seal cover 10 is fitted into the notch 6b to form a static sealing ring. 6 regulates the rotation due to sliding with the rotary sealing ring 4.

As shown in FIG. 7, the knock pin 7A is formed to have substantially the same diameter as the hole portion 10b of the seal cover 10, and has a press-fitting portion 27 as a fixing portion that can be press-fitted and fixed to the hole portion 10b, and the press-fitting portion 27. It is mainly composed of a fitting portion 17 which is formed to have a large diameter and projects substantially horizontally from the seal cover 10.

Further, the fitting portion 17 of the knock pin 7A is fitted in the notch portion 6b as a recess formed on the back surface 6a side of the static sealing ring 6 in a loosely fitted state in the axial direction so as to correspond to the arrangement of the knock pin 7A. The static sealing ring 6 is allowed to move in the axial direction while restricting the movement in the circumferential direction due to sliding with the rotary sealing ring 4. The notch portion 6b is formed to be larger than the fitting portion 17 of the knock pin 7A and to be longer in the axial direction.

The fitting portion 17 is formed in a prismatic shape, and a plurality of dimple portions 34a are arranged in a matrix in an orderly manner in the radial direction and the axial direction on the outer peripheral surface 17b thereof, and the plurality of dimple portions 34a are formed in the radial direction. A plurality of connecting dimple portions 34 connected by the rectangular connecting groove portions 34b are formed in the axial direction. More specifically, the connecting dimple portion 34 is formed of a plurality of dimple portions 34a and a connecting groove portion 34b, and the plurality of dimple portions 34a are formed in a lateral view elliptical shape and a bottom portion in a cross-sectional view curved shape. Further, a major axis portion is formed in the axial direction and is separated at a predetermined pitch in the axial direction. The connecting groove portion 34b is bored in a rectangular shape in a cross-sectional view with the same width and the same depth, and is formed in the radial direction so as to communicate a plurality of dimple portions 34a arranged side by side in the radial direction. From this, the fluid is always supplied to each dimple portion 34a, the lubricity can be maintained, and the fluid film F is formed over the entire surface of the contact surface between the outer peripheral surface 17b of the fitting portion 17 and the notch portion 6b. It is designed to be able to. The connecting groove portion 34b is not limited to one in which a plurality of dimple portions 34a are communicated in the radial direction, and may be one in which a plurality of dimple portions 34a are communicated in the axial direction, or a plurality of dimple portions 34a are radially and axially communicated with each other. It may be communicated in the direction.

As shown in FIG. 8, as a modification of the connecting dimple portion 34 formed in the fitting portion 17, the knock pin 7B is opened to the radial outer surface 17a and the inner surface 17c of the knock pin 7B and has the same width and depth in cross-sectional viewing. The communication dimple portion 44 in which the communication groove portion 44b bored in the shape is formed may be arranged. By doing so, the fluid can be introduced from the outer surface 17a of the knock pin 7B, and the fluid can be constantly supplied to each dimple portion 44a, and the lubricity can be further maintained.

Further, although not particularly shown, a connecting dimple portion or a communicating dimple portion may be formed on the outer peripheral surface of the drive pin 5 that prevents the rotary sealing ring 4 from rotating with respect to the sleeve 3 as in the knock pin 7A described above.

As described above in the second embodiment and the modified example, since the communication groove portion 34b for communicating the plurality of dimple portions 34a is provided, the fluid is always supplied to each dimple portion 34a to maintain the lubricity. be able to.

As described above, examples of the present invention have been described with reference to the drawings, but the specific configuration is not limited to these examples, and the present invention may be changed or added without departing from the gist of the present invention. Included in the invention.

For example, in the above embodiment, the fitting portion 17 of the knock pins 7A and 7B has been described as being prismatic, but the present invention is not limited to this, and may be cylindrical or hexagonal columnar.

Further, in the above embodiment, the dimple portion 14 is formed on the protruding portion 91, but the present invention is not limited to this, and the dimple portion may be formed on the drive pin 5.

Further, in the above embodiment, the static sealing ring 6 or the rotary sealing ring 4 is formed with a recess constituting the detent mechanism, but the present invention is not limited to this. For example, the static sealing ring 6 is attached to the seal cover 10 for the mechanical seal. When a locking body for stopping or a locking body for locking the rotary sealing ring 4 to the sleeve 3 is configured, a recess may be formed in the locking body. Further, for example, a recess may be formed in the seal cover 10 or the sleeve 3, and the fitting portion fitted in the recess may be provided in the static sealing ring 6 or the rotary sealing ring 4.

Further, in the above embodiment, the detent mechanism is applied to the tandem type mechanical seal 1, but the detent mechanism according to the present invention is not limited to this, even if it is applied to the single type and double type mechanical seals. Alternatively, it may be applied to sliding parts such as thrust bearings.

Further, as described in the modified example of the first embodiment, the matter of providing the dimple portion on the inner wall surface of the recess can be applied to the second embodiment and the like.

1 Mechanical seal (sliding parts)
2 Rotating shaft 3 Sleeve 4, 4'Rotating sealing ring 5, 5'Drive pin 6, 6'Resting sealing ring 6a Back surface 6b Notch (recess)
6c Outer surface 6d Recess 6e Inner wall surface 7,7' Knock pin 7A Knock pin 7B Knock pin 8 Coil spring 9 Case 10 Seal cover 10a Hole 10b Hole 11 Connecting bolt 14 Dimple 14a Dimple 14b Dimple 17 Fitting 17b Outer surface 19 Barrier liquid inflow port 20 Rotating ring holding member 27 Press-fitting part 29 Barrier liquid outflow port 34 Connecting dimple part 34b Connecting groove part 44 Communication dimple part 44b Communication groove part B Barrier liquid D Dimple forming area E Sliding part F Fluid film H Sealed fluid M Machine body L1 Communicating passage R Rotating side element S Resting side element S1 Contact area S2 Non-contact area Z Space

Claims (7)

The rotating sliding ring is used for a sliding component in which a rotating sliding ring that rotates in the circumferential direction together with a rotating side element attached to the rotating shaft and a stationary sliding ring fixed to the stationary side element slide relative to each other. A detent mechanism that detents the rotating side element or detents the resting sliding ring from the resting side element.
The detent mechanism is composed of a recess and an fitting portion to be fitted into the recess, and a dimple portion having a concave shape is provided on the inner surface of the recess or the outer surface of the fitting portion. Stop mechanism. The detent mechanism according to claim 1, wherein the dimple portion extends over a contact region between the outer surface of the fitting portion and the inner surface of the recess, and a non-contact region excluding the contact region. The detent mechanism according to claim 1 or 2, wherein the dimple portion extends in the axial direction of the sliding ring. The detent mechanism according to claim 3, wherein the dimple portion is formed in an elliptical shape having a major axis in the axial direction of the sliding ring. The detent mechanism according to any one of claims 1 to 4, wherein the dimple portion is provided on the outer surface of the fitting portion in plurality. The circumference according to claim 5, wherein a dimple forming region having the plurality of dimple portions is formed over a contact region between the outer surface of the fitting portion and the inner surface of the recess and a non-contact region excluding the contact region. Stop mechanism. The detent mechanism according to claim 5 or 6, wherein a communication groove for communicating the plurality of dimple portions is provided.

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