JP6941479B2 - Seal structure and mechanical seal - Google Patents

Description

The present invention relates to a seal structure and a mechanical seal.

Conventionally, as a device for sealing the fluid to be sealed inside the rotating device, a static sealing ring fixed to the casing side and a rotary sealing ring rotatably attached to the rotating shaft side are provided. A non-contact mechanical seal that holds the sealing surfaces in a non-contact state by supplying a sealing gas between the sealing surfaces of the rotary sealing ring facing each other is known (see, for example, Patent Document 1).

In such a non-contact mechanical seal, one seal surface is formed flat, and a dynamic pressure generating groove (also referred to as “groove”) through which the seal gas flows is formed on the other seal surface. Then, when the rotary sealing ring is rotated, the dynamic pressure of the seal gas generated in the dynamic pressure generating groove acts as a force (levitation force) for separating the two sealing surfaces from each other, so that the two sealing surfaces are not separated from each other. It is held in contact.

Japanese Unexamined Patent Publication No. 9-303571

However, in the conventional non-contact mechanical seal, the flow rate of the seal gas supplied to the dynamic pressure generation groove is insufficient, or the size of the entire seal is limited, so that both seal surfaces are separated from each other. It may not be possible to obtain the required dynamic pressure. When the mechanical seal is operated in such a state, there is a problem that both seal surfaces come into contact with each other to cause deformation or damage, and the seal performance is significantly deteriorated.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a seal structure and a mechanical seal capable of increasing the dynamic pressure for holding both sealing surfaces in a non-contact state.

(1) The seal structure of the present invention includes a pair of sealing rings that can rotate relative to each other and are arranged so as to face each other in the axial direction, and seal gas is provided between the sealing surfaces of the pair of sealing rings that face each other. Is supplied to provide a sealing structure that seals between the two sealing surfaces while keeping the two sealing surfaces in a non-contact state, and one of the sealing rings has a predetermined interval in the circumferential direction on the sealing surface. The seal gas is formed in plurality at intervals, and has a dynamic pressure generating groove into which the seal gas flows. The plurality of first groove portions have a first groove portion, and the plurality of first groove portions communicate with one of the plurality of dynamic pressure generating grooves during the relative rotation of the pair of sealing rings, and the plurality of dynamic pressure generating grooves. It is formed so as to alternately repeat a non-communication state that does not communicate with any of the above.

According to this sealing structure, during the relative rotation of the pair of sealing rings, a plurality of dynamic pressure generating grooves formed on the sealing surface of one sealing ring and a plurality of firsts formed on the sealing surface of the other sealing ring. 1 The groove portions alternately repeat a communicating state in which they communicate with each other and a non-communication state in which they do not communicate with each other. At that time, in the non-communication state, the seal gas staying in the first groove portion becomes high pressure due to the inertial force accompanying the relative rotation, and when the communication state is reached from this state, the high-pressure seal gas in the first groove portion Flows into the dynamic pressure generation groove. Thereby, the dynamic pressure generated in the dynamic pressure generation groove can be increased. As a result, the separation distance between the two sealing surfaces is increased, so that the deterioration of the sealing performance due to the contact between the two sealing surfaces can be effectively suppressed.

(2) In the seal structure, the other sealing ring communicates with the first groove portion on the sealing surface and does not communicate with any of the plurality of dynamic pressure generating grooves during the relative rotation of the pair of sealing rings. It is preferable to further have a second groove portion into which the seal gas flows, which is formed as described above.
In this case, in the state of communication between the first groove and the dynamic pressure generating groove, the seal gas having a high pressure in the first groove flows out to the dynamic pressure generating groove, so that the pressure in the first groove is temporary. However, the seal gas in the second groove flows into the first groove in order to equalize the pressure. As a result, the seal gas in the first groove can be reliably increased in pressure when the communication state is changed to the non-communication state again.

(3) In the seal structure, it is preferable that the second groove portion is formed in an annular shape so as to communicate with all of the plurality of first groove portions when viewed from the front in the axial direction.
In this case, it can be easily formed as compared with the case where a plurality of second groove portions are formed corresponding to each first groove portion.

(4) In the seal structure, it is preferable that the outer shape of each of the first groove portions is formed in an arc shape when viewed from the front in the axial direction.
In this case, the first groove portion can be easily formed.

(5) In the seal structure, it is preferable that each of the first groove portions is formed so that the maintenance time of the non-communication state is shorter than the maintenance time of the communication state.
In this case, it is possible to shorten the time during which the seal gas in the first groove portion does not flow into the dynamic pressure generating groove in the non-communication state, so that it is possible to suppress deterioration of the sealing performance.

(6) The mechanical seal of the present invention has the seal structure according to any one of (1) to (5) above.
According to this mechanical seal, during the relative rotation of the pair of sealing rings, a plurality of dynamic pressure generating grooves formed on the sealing surface of one sealing ring and a plurality of firsts formed on the sealing surface of the other sealing ring. 1 The groove portions alternately repeat a communicating state in which they communicate with each other and a non-communication state in which they do not communicate with each other. At that time, in the non-communication state, the seal gas staying in the first groove portion becomes high pressure due to the inertial force accompanying the relative rotation, and when the communication state is changed from this state, the high-pressure seal gas in the first groove portion is released. It flows into the dynamic pressure generation groove. Thereby, the dynamic pressure generated in the dynamic pressure generation groove can be increased. As a result, the separation distance between the two sealing surfaces is increased, so that the deterioration of the sealing performance due to the contact between the two sealing surfaces can be effectively suppressed.

According to the present invention, it is possible to increase the dynamic pressure for holding both sealing surfaces in a non-contact state.

It is sectional drawing which shows the mechanical seal provided with the seal structure which concerns on 1st Embodiment of this invention. It is a front view which looked at the sealing surface of a static sealing ring from an axial direction. It is a front view which looked at the sealing surface of a rotary sealing ring from an axial direction. It is an enlarged cross-sectional view of the main part of FIG. The positional relationship between the first and second groove portions and the dynamic pressure generating groove during rotation of the rotary sealing ring is shown, where (a) is a communicating state and (b) is a non-communication state. It is a front view which looked at the sealing surface of the static sealing ring in the sealing structure which concerns on 2nd Embodiment of this invention from the axial direction. It is a front view which looked at the sealing surface of the rotary sealing ring in the sealing structure which concerns on 2nd Embodiment from the axial direction. The positional relationship between the first and second grooves and the dynamic pressure generating groove during the rotation of the rotary sealing ring of the second embodiment is shown, where (a) is a communicating state and (b) is a non-communication state. It is in communication.

Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view showing a mechanical seal having a seal structure according to the first embodiment of the present invention. In FIG. 1, the mechanical seal M is used for a high-speed rotating device such as a turbine or a compressor, and is arranged between a casing 1 of the high-speed rotating device and a rotating shaft 2 inserted into the casing 1. The mechanical seal M has an inner side of the machine (first space) A on the outer side in the radial direction and one side in the axial direction, and the outer side of the machine (second space) on the inner side in the radial direction and the other side in the axial direction, sandwiching between the seal surfaces described later. By partitioning from B, the inside A of the machine is set to low pressure and the outside B of the machine is set to high pressure to prevent the sealed fluid existing in the inside A of the machine from leaking to the outside B of the machine.

The mechanical seal M is fixed to an annular rotary seal ring 3 attached to the rotary shaft 2, a stopper ring 4 externally fitted and fixed to the rotary shaft 2, and the stopper ring 4 as a rotary side unit. A sleeve 5 with a flange 5a fitted to the rotating shaft 2 is provided.

The rotary sealing ring 3 is fitted on the sleeve 5 and is sandwiched between the flange 5a of the sleeve 5 and the stopper ring 4 and fixed to the rotary shaft 2. As a result, the rotary sealing ring 3 can rotate integrally with the rotary shaft 2. The end surface of the machine outer side B of the rotary sealing ring 3 is a sealing surface 3a. The sleeve 5 and the stopper ring 4 are fixed by bolts 6, and the stopper ring 4 is fixed to the rotating shaft 2 by a set screw 7.

An O-ring 8 that seals between the machine inside A and the machine outside B is interposed between the rotary sealing ring 3 and the sleeve 5. Further, an O-ring 9 for sealing between the machine inside A and the machine outside B is interposed between the rotating shaft 2 and the sleeve 5. These O-rings 8 and 9 prevent the sealed fluid of the machine inside A from leaking to the machine outside B between the rotary sealing ring 3 and the rotary shaft 2.

As the stationary side unit, the mechanical seal M includes an annular static sealing ring 10 that faces the rotary sealing ring 3 in the axial direction, an annular seal case 11 for attaching the static sealing ring 10 to the casing 1, and a static sealing ring. It is provided with a spring 12 which is an elastic member that presses the 10 toward the rotary sealing ring 3.

The seal case 11 is composed of a first case 13 and a second case 14. Both cases 13 and 14 are formed in an annular shape and are fixed to the casing 1 by bolts 15. The second case 14 has a wall portion 17 that faces the static sealing ring 10 in the axial direction, and a cylindrical portion 18 that extends in the axial direction (in the direction of the machine inside A) inside the wall portion 17 in the radial direction. ing. An O-ring 19 is interposed between the inner peripheral surface of the cylindrical portion 18 and the inner peripheral surface of the static sealing ring 10. In the second case 14, a gas supply hole 16 for supplying a seal gas (for example, air) is formed so as to penetrate in the radial direction.

The static sealing ring 10 is radially inside the first case 13, and is arranged so as to be sandwiched between the second case 14 and the rotary sealing ring 3. An O-ring 20 is arranged between the inner peripheral surface of the first case 13 and the outer peripheral surface of the static sealing ring 10.

On the outer side B of the stationary sealing ring 10, a plurality of holes 21 recessed in the axial direction from the outer side B toward the inner side A are formed at equal intervals in the circumferential direction. The spring 12 is arranged in each hole 21. One end of the spring 12 is in contact with the bottom surface of the hole 21, and the other end is in contact with the wall surface 17a of the machine inside A of the wall portion 17 of the second case 14. The static sealing ring 10 is pressed toward the rotary sealing ring 3 by the elastic restoring force of the spring 12.

The inner peripheral surface and the outer peripheral surface of the static sealing ring 10 are supported from both sides in the radial direction by the O-ring 19 and the O-ring 20. Then, the static sealing ring 10 can move in the axial direction against the elastic force of the spring 12. The end surface of the machine inside A of the static sealing ring 10 is a sealing surface 10a facing the sealing surface 3a of the rotary sealing ring 3.

An annular space S in which the sealing gas is supplied through the gas supply hole 16 between the inner peripheral surface of the machine inner surface A of the static sealing ring 10 and the inner peripheral surface of the cylindrical portion 18 and the outer peripheral surface of the stopper ring 4. Is formed. A dynamic pressure generating groove 24 into which the sealing gas flows from the space S is formed on the sealing surface 10a of the static sealing ring 10. The seal gas flowing into the dynamic pressure generating groove 24 generates a force (levitation force) that separates the sealing surfaces 3a and 10a from each other by the dynamic pressure generated when the rotary sealing ring 3 rotates.

Specifically, the dynamic pressure generates a force that presses the sealing surface 10a of the static sealing ring 10 toward the outside B of the machine against the elastic force of the spring 12. As a result, the seal gas that has flowed into the dynamic pressure generation groove 24 flows out in the radial direction through the gap between the two seal surfaces 3a and 10a. Then, while the seal gas is being supplied, a flow is always generated from the space S inside in the radial direction to the outside in the radial direction via both the sealing surfaces 3a and 10a.

Then, the static sealing ring 10 moves to the outside B of the machine to a position where the resultant force of the gas pressure (dynamic pressure) of the seal gas in the gap and the pressure of the sealed fluid of the inside A of the machine and the elastic force of the spring 12 antagonize each other. After that, it is held in that position. Then, the seal gas filled in the gap brings the static sealing ring 10 and the rotary sealing ring 3 into a non-contact state, and the rotary shaft 2 and the rotary sealing ring 3 rotate while maintaining this state.

Therefore, it is possible to seal between the sealing surfaces 3a and 10a by supplying the sealing gas between the sealing surfaces 3a and 10a when the rotating shaft 2 rotates. In the present embodiment, the rotary sealing ring 3 and the static sealing ring 10 seal between the sealing surfaces 3a and 10a while keeping the sealing surfaces 3a and 10a of the pair of sealing rings facing each other in a non-contact state. The seal structure 25 is configured.

FIG. 2 is a front view of the sealing surface 10a of the static sealing ring 10 as viewed from the axial direction. In FIG. 2, a plurality (8 in the example) of the dynamic pressure generating grooves 24 (portions indicated by hatching in the drawing) are formed on the sealing surface 10a of the static sealing ring 10 at equal intervals in the circumferential direction. There is. Each dynamic pressure generating groove 24 is opened at the inner peripheral end of the static sealing ring 10 so that the sealing gas flows in from the space S. Each dynamic pressure generating groove 24 is formed so as to extend radially outward from the inner peripheral end of the static sealing ring 10 and toward the rotational direction R side of the rotary sealing ring 3.

FIG. 3 is a front view of the sealing surface 3a of the rotary sealing ring 3 as viewed from the axial direction. In FIG. 3, a plurality of first groove portions 31 (portions indicated by cross hatching in the figure) and one second groove portion 32 (portions indicated by hatching in the drawing) are formed on the sealing surface 3a of the rotary sealing ring 3. Is formed. The second groove portion 32 is formed in a radial inner portion of the sealing surface 3a, for example, in an annular shape concentric with the rotary sealing ring 3.

The plurality of first groove portions 31 are formed at equal intervals in the circumferential direction on the radial outer side of the second groove portion 32, and each of these first groove portions 31 communicates with the second groove portion 32. The outer shape of each first groove portion 31 is formed in an arc shape so as to project radially outward from the outer circumference of the second groove portion 32. The number of the first groove portions 31 of the present embodiment is the same as the number of the dynamic pressure generating grooves 24 (8).

FIG. 4 is an enlarged cross-sectional view of a main part of FIG. In FIG. 4, the depths of the first groove portion 31 and the second groove portion 32 of the rotary sealing ring 3 in each axial direction (left-right direction in the drawing) are set to the same depth H. The depth H is set deeper than the axial depth h of the dynamic pressure generating groove 24 of the static sealing ring 10.

As shown in FIG. 4, the second groove portion 32 of the rotary sealing ring 3 is formed at a position whose entire circumference corresponds to the space S, and communicates with the space S. On the other hand, the first groove portion 31 of the rotary sealing ring 3 is formed at a position corresponding to the dynamic pressure generating groove 24 of the static sealing ring 10 on the radial outer side of the space S, and is formed in the dynamic pressure generating groove 24. Communicating. As a result, as shown by the broken line arrow in FIG. 4, the seal gas in the space S passes through each of the first groove portions 31 from the second groove portion 32 and flows into the dynamic pressure generating groove 24.

5 (a) and 5 (b) are explanatory views showing the positional relationship between the first and second groove portions 31 and 32 and the dynamic pressure generating groove 24 as viewed from the axial direction during the rotation of the rotary sealing ring 3. Is. In FIGS. 5 (a) and 5 (b), the first groove 31 is cross-hatched (including the black-painted portion in FIG. 5 (b)), the second groove 32 is hatched, and the dynamic pressure generating groove 24 is not hatched. It is shown by. Further, in FIGS. 5A and 5B, for convenience of explanation, the portions other than the first and second groove portions 31 and 32 of the rotary sealing ring 3 and the radial outer side of the sealing surface 10a of the static sealing ring 10 The part is not shown.

As shown in FIGS. 5A and 5B, the second groove portion 32 is formed radially inside the plurality of dynamic pressure generating grooves 24. That is, the second groove portion 32 is formed so as not to communicate with any of the plurality of dynamic pressure generating grooves 24 when rotating in the rotation direction R together with the rotary sealing ring 3.

When the plurality of first groove portions 31 are rotating in the rotation direction R together with the rotary sealing ring 3, the plurality of first groove portions 31 are in a communicating state (state in FIG. 5A) in which they communicate with any of the plurality of dynamic pressure generating grooves 24. It is formed so as to alternately repeat a non-communication state (state of FIG. 5B) that does not communicate with any of the dynamic pressure generation grooves 24 of the above.

Here, the “communication state” is not limited to the state in which the entire first groove portion 31 communicates with the dynamic pressure generating groove 24 (overlaps in the axial direction) as shown in FIG. 5 (a). A state in which a part of the first groove portion 31 communicates with a part of the dynamic pressure generating groove 24 is also included.
Further, the “non-communication state” refers to a case other than the communication state, and as shown in FIG. 5 (b), the entire first groove portion 31 is located between the adjacent dynamic pressure generating grooves 24. Includes states only.

In the present embodiment, in order to make the outer shape of each first groove portion 31 as large as possible, as shown in FIG. 5B, each first groove portion 31 and both sides in the circumferential direction thereof are in a non-communication state. Only a small gap is formed between the adjacent dynamic pressure generating groove 24. Therefore, when the rotary sealing ring 3 rotates slightly from the non-communication state shown in FIG. 5B, a part of each first groove portion 31 communicates with a part of the adjacent dynamic pressure generating groove 24. It immediately switches to the communication state.

Then, until the rotary sealing ring 3 further rotates and each first groove portion 31 goes through the state shown in FIG. 5 (a) to the next non-communication state (state shown in FIG. 5 (b)). , The communication state is maintained. Therefore, in the present embodiment, the maintenance time of the communicating state is significantly longer than the maintenance time of the non-communication state during the rotation of the rotary sealing ring 3. As a result, the high-pressure seal gas in the first groove portion 31 can be reliably flowed into the dynamic pressure generation groove 24 during the communication state.

With the above configuration, during the rotation of the rotary sealing ring 3, the plurality of first groove portions 31 rotate together with the rotary sealing ring 3, so that a plurality of dynamic pressures of the plurality of first groove portions 31 and the static sealing ring 10 are generated. The grooves 24 alternately repeat a communicating state in which they communicate with each other and a non-communication state in which they do not communicate with each other. At that time, in the non-communication state, the seal gas stays in the first groove portion 31 without flowing to the dynamic pressure generating groove 24, so that the seal gas in the first groove portion 31 has inertia due to the high-speed rotation of the rotary sealing ring 3. Due to the force, a high pressure is applied in the black-painted region of FIG. 5 (b). At this point, the pressure on the inside A of the machine, the pressure on the outside B and the second groove 32 , and the pressure on the black-painted portion (high pressure region) of the first groove 31 are higher in this order (pressure on the inside A < The pressure on the outside B of the machine and the pressure on the second groove 32 <the pressure on the black-painted portion on the first groove 31).

After that, when the seal gas having a high pressure in the black-painted region of the first groove portion 31 changes from the non-communication state (see FIG. 5B) to the communication state (see FIG. 5A), It flows into the dynamic pressure generation groove 24. Thereby, the dynamic pressure generated in the dynamic pressure generation groove 24 can be increased. As a result, the separation distance between the two sealing surfaces 3a and 10a is increased, so that the deterioration of the sealing performance due to the contact between the two sealing surfaces 3a and 10a can be effectively suppressed.

Further, when the communication state is changed from the non-communication state, the seal gas having a high pressure in the first groove portion 31 flows out to the dynamic pressure generation groove 24, so that the pressure in the first groove portion 31 temporarily decreases. However, the seal gas in the second groove 32 flows into the first groove 31 in order to equalize the pressure. As a result, the seal gas in the first groove portion 31 can be quickly filled, so that the seal gas in the first groove portion 31 can be quickly increased in pressure when the communication state is changed to the non-communication state again. can.

Further, since the second groove portion 32 is formed in an annular shape so as to communicate with all of the plurality of first groove portions 31 when viewed from the front in the axial direction, the second groove portion 32 is formed in each of the first groove portions 31. It can be easily formed as compared with the case where a plurality of pieces are formed corresponding to.
Further, since the outer shape of each first groove portion 31 is formed in an arc shape when viewed from the front in the axial direction, the first groove portion 31 can be easily formed.

Further, since the same number of first groove portions 31 as the number of dynamic pressure generating grooves 24 are formed at equal intervals in the circumferential direction, the seal gas having a high pressure in the black-painted portion region of each first groove portion 31 can be used. It can be evenly flowed into all the dynamic pressure generating grooves 24. As a result, the separation distance between the sealing surfaces 3a and 10a can be uniformly increased in the entire circumferential direction.

In the present embodiment, the outer shape of the first groove portion 31 is formed as large as possible, but it may be formed smaller than that of the present embodiment. In this case, the time during which the entire first groove portion 31 is located between the adjacent dynamic pressure generating grooves 24, that is, the maintenance time in the non-communication state is longer than that in the present embodiment, and therefore, the first groove portion 31 is correspondingly longer. The seal gas in the groove 31 can have a higher pressure. As a result, the dynamic pressure generated in the dynamic pressure generation groove 24 is further increased, so that the separation distance between the sealing surfaces 3a and 10a can be further increased.

[Second Embodiment]
6 and 7 both show the seal structure 25 according to the second embodiment of the present invention, and in particular, FIG. 6 is a front view of the seal surface 10a of the static sealing ring 10 as viewed from the axial direction. FIG. 7 is a front view of the sealing surface 3a of the rotary sealing ring 3 as viewed from the axial direction.
In the seal structure 25 of the second embodiment, the radial outside of the static sealing ring 10 and the rotary sealing ring 3 is a high-pressure machine outside B, and the radial inside of the static sealing ring 10 and the rotary sealing ring 3 is a sealed fluid. It differs from the first embodiment in that it is the existing low-pressure machine inside A. Therefore, in the second embodiment, although not shown, a space (corresponding to the space S in the first embodiment) in which the seal gas flows in from the outside is formed on the radial outer side of the static sealing ring 10 and the rotary sealing ring 3. Has been done.

In FIG. 6, a plurality of (8 in the example) dynamic pressure generating grooves 24'(portions indicated by hatching in the figure) are formed on the sealing surface 10a of the static sealing ring 10 from the radial outside of the static sealing ring 10. It is opened at the outer peripheral end of the static sealing ring 10 so that the sealing gas can flow in. Each dynamic pressure generating groove 24'is formed so as to spirally extend from the outer peripheral end of the static sealing ring 10 toward the rotational direction R side of the rotary sealing ring 3 and inside in the radial direction.

In FIG. 7, on the sealing surface 3a of the rotary sealing ring 3, a plurality of first groove portions 31'(parts indicated by hatching in the drawing) are radially inside the second groove portion 32'formed in an annular shape. (Parts shown by cross-hatching in the figure) are formed at equal intervals in the circumferential direction. Each of the plurality of first groove portions 31'communicates with the second groove portion 32'. The outer shape of each first groove portion 31'is formed in an arc shape so as to project radially inward from the inner circumference of the second groove portion 32'.

8 (a) and 8 (b) show the positional relationship between the first and second groove portions 31'and 32'and the dynamic pressure generating groove 24'when the rotary sealing ring 3 is rotating. It is explanatory drawing which shows. In FIGS. 8 (a) and 8 (b), the first groove portion 31'is cross-hatched (including the black-painted portion in FIG. 8 (b)), the second groove portion 32'is hatched, and the dynamic pressure generating groove 24'is formed. It is shown by no hatching. Further, in FIGS. 8A and 8B, for convenience of explanation, parts other than the first and second groove portions 31'and 32'of the rotary sealing ring 3 are not shown.

As shown in FIGS. 8A and 8B, the second groove portion 32'is formed radially outside the plurality of dynamic pressure generating grooves 24'. That is, the second groove portion 32'is formed so as not to communicate with any of the plurality of dynamic pressure generating grooves 24'when rotating in the rotation direction R together with the rotary sealing ring 3.

When the plurality of first groove portions 31'are rotating in the rotation direction R together with the rotary sealing ring 3, the plurality of first groove portions 31'communicate with any of the plurality of dynamic pressure generating grooves 24' (the state of FIG. 8A). , The non-communication state (state of FIG. 8B) that does not communicate with any of the plurality of dynamic pressure generation grooves 24'is formed so as to alternately repeat. Since the other configurations of the second embodiment are the same as those of the first embodiment, the description thereof will be omitted.

With the above configuration, during the rotation of the rotary sealing ring 3, the plurality of first groove portions 31'rotate together with the rotary sealing ring 3, so that the plurality of first groove portions 31'and the plurality of static sealing rings 10 move. The pressure generating groove 24'alternately repeats a communicating state in which they communicate with each other and a non-communication state in which they do not communicate with each other. At that time, in the non-communication state, the seal gas stays in the first groove portion 31'without flowing to the dynamic pressure generating groove 24', so that the seal gas in the first groove portion 31' rotates at high speed of the rotary sealing ring 3. Due to the inertial force that accompanies this, the pressure becomes high in the black-painted region of FIG. 8 (b). At this point, the pressure on the inside A of the machine, the pressure on the outside B of the machine and the pressure of the second groove 32' , and the pressure of the black-painted portion of the first groove 31'are higher in this order.

After that, when the seal gas having a high pressure in the black-painted region of the first groove portion 31'changes from the non-communication state (see FIG. 8B) to the communication state (see FIG. 8A). , Flows into the dynamic pressure generation groove 24'. Thereby, the dynamic pressure generated in the dynamic pressure generation groove 24'can be increased. As a result, the separation distance between the two sealing surfaces 3a and 10a is increased, so that the deterioration of the sealing performance due to the contact between the two sealing surfaces 3a and 10a can be effectively suppressed.

Further, when the communication state is changed from the non-communication state, the seal gas having a high pressure in the first groove portion 31'flows out to the dynamic pressure generation groove 24', so that the pressure in the first groove portion 31'is temporary. However, the seal gas in the second groove portion 32'flows into the first groove portion 31'in order to equalize the pressure. As a result, the seal gas can be quickly filled in the first groove 31', so that the seal gas in the first groove 31'is quickly increased in pressure when the communication state is changed to the non-communication state again. be able to.

[others]
The rotary sealing ring 3 in each of the above embodiments is formed with a first groove portion 31 (31') and a second groove portion 32 (32'), but at least a first groove portion 31 (31') is formed. Just do it. In this case, the seal gas supplied from the outside into the mechanical seal M may be directly flowed into the first groove portion 31. Further, although the case where the seal structure 25 of the above embodiment is used for the mechanical seal M has been described, it can also be applied to other seal devices.

In the seal structure 25 in each of the above embodiments, the dynamic pressure generating groove 24 (24') is formed on the static sealing ring 10 side, and the first and second groove portions 31, 32 (31', 32') are formed on the rotary sealing ring 3 side. ) Is formed, but the first and second groove portions 31, 32 (31', 32') are formed on the static sealing ring 10 side, and the dynamic pressure generating groove 24 (24') is formed on the rotary sealing ring 3 side. It may be formed.

The number of the first groove portions 31 (31') in each of the above embodiments is the same as the number of the dynamic pressure generating grooves 24 (24'), but is smaller than the number of the dynamic pressure generating grooves 24 (24'). May be good. Further, the outer shape of the first groove portion 31 (31') is not limited to the arc shape, and if there is a region where the pressure is high due to the inertial force accompanying the rotation of the rotary sealing ring 3, the outer shape may be a polygonal shape or the like. It may be formed in another shape.

The second groove portion 32 (32') in each of the above embodiments is formed in an annular shape, but may be formed in another ring shape such as a polygonal ring shape. Further, in the above embodiment, one second groove portion 32 (32') is formed so as to communicate with all of the plurality of first groove portions 31 (31'), but each first groove portion 31 (31') A plurality of second groove portions 32 (32') that communicate with each other individually may be formed.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims, not the above-mentioned meaning, and is intended to include the meaning equivalent to the scope of claims and all modifications within the scope.

3 Rotating sealed ring (sealed ring)
3a Sealing surface 10 Static sealing ring (sealing ring)
10a Seal surface 24, 24'Dynamic pressure generating groove 25 Seal structure 31, 31' First groove 32, 32' Second groove M Mechanical seal

Claims (3)

A pair of seal rings disposed opposite and and axially rotatable relative to one another, the opposing portion of opposing sealing faces of the pair of seal rings, radially from the other end thereof radial one A seal structure that seals the facing portions while holding the facing portions of both sealing surfaces in a non-contact state by supplying the sealing gas toward the seal gas.
One of the sealing rings is formed on the sealing surface between the radial end of the facing portion and the middle of the radial other end side, and a plurality of the sealing rings are formed at predetermined intervals in the circumferential direction . , Has a dynamic pressure generating groove into which the seal gas flows,
The other sealing ring was formed on the sealing surface between the radial end of the facing portion and the middle of the radial other end side, and a plurality of the sealing rings were formed at predetermined intervals in the circumferential direction . , Has a first groove into which the seal gas flows,
The plurality of first groove portions communicate with each of the plurality of dynamic pressure generating grooves and non-communication not communicating with any of the plurality of dynamic pressure generating grooves during the relative rotation of the pair of sealing rings. It is formed so that the state and the state are repeated alternately.
The other sealing ring is formed so as to communicate with the radial end of the first groove portion and not to communicate with any of the plurality of dynamic pressure generating grooves during the relative rotation of the pair of sealing rings on the sealing surface. Further having a second groove portion into which the seal gas flows in,
The second groove portion is a seal structure formed in an annular shape so as to communicate with all of the plurality of first groove portions when viewed from the front in the axial direction. The seal structure according to claim 1, wherein the outer shape of each first groove portion is formed in an arc shape when viewed from the front in the axial direction. A mechanical seal having the seal structure according to claim 1 or 2.

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