JP2013050141A - Mechanical seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical seal that maintains high sealing performance over a long period of time.SOLUTION: The mechanical seal 1 includes an annular spring retainer 4 which retains a static sealing ring 3 and is energized toward a rotative sealing ring 3 together with the static sealing ring 3. The spring retainer 4 includes: a retainer body 11 which has a flange part 11b abutted on the back surface of the static sealing ring; and an annular pressing plate 12 which retains the static sealing ring 3 by fastening and clamping the static sealing ring 3 toward the flange part 11b. A tapered surface 11b2, which is abutted on the static sealing ring 3 and is inclined to gradually expand the diameter toward the rotative sealing ring 2, is formed on the flange part 11b. An outer side tapered surface 3c, which can be abutted in accordance with the tapered surface 11b2, is formed on the back surface of the static sealing ring 3. An O-ring 30 is arranged between the tapered surface 11b2 and the outer side tapered surface 3c.

Description

  The present invention relates to an end surface contact type mechanical seal using a split type sealing ring.

Conventionally, in order to seal a clearance between a rotating shaft and a casing, a mechanical device having a rotating sealing ring fixed to the rotating shaft and a stationary sealing ring fixed to the casing side and in sliding contact with the sealing end surface of the rotating sealing ring. A seal may be used. Some of such mechanical seals employ a split type sealing ring formed by combining a plurality of arc-shaped divided bodies in a ring shape with a stationary sealing ring for easy disassembly and assembly.
As shown in FIG. 4, in the mechanical seal, the split stationary seal ring 100 is fixed to a spring retainer 101 fixed to a casing (not shown), and one end face 100 a is a seal of the rotary seal ring 102. The surface 102a is slidably contacted. The stationary seal ring 100 is a tapered surface whose outer peripheral surface 100b gradually increases in diameter toward the casing.

The spring retainer 101 is a member for fixing a spring (not shown) for biasing the stationary seal ring 100 to the rotary seal ring 102, and a flange portion with which the other end surface 100 c of the stationary seal ring 100 is in contact. A retainer main body 103 having 103a and an annular pressing plate 104 holding a stationary sealing ring 100 between the flange portion 103a are provided.
The pressing plate 104 has a contact surface 104 a that contacts the outer peripheral surface 100 b of the stationary sealing ring 100. Since the contact surface 104 a is in contact with the outer peripheral surface 100 b of the stationary seal ring 100 that is gradually tapered toward the casing side, the pressing plate 104 is axially moved so as to approach the retainer body 103. By being tightened, a force in a direction to reduce the diameter acts on the stationary seal ring 100, and a force in a direction to be pressed against the flange portion 103a acts.
As a result, the stationary seal ring 100 is pressed between the retainer body 103 and the pressing plate 104 in a state where the abutting surfaces with which the respective divided bodies are abutted are pressed against each other while being pressed against the flange portion 103a. For example, see Patent Document 1).

JP 2004-251376 A

In the above-described conventional mechanical seal, the split stationary seal ring 100 is sandwiched and fixed between the retainer body 103 and the pressing plate 104. For example, if the pressing plate 104 is not tightened uniformly, In some cases, the divided bodies constituting the ring 102 are distorted, and a gap is generated in the abutting surface of each divided body, thereby reducing the sealing performance.
In addition, if the presser plate 104 is not sufficiently tightened, the force in the direction of diameter reduction acting on the stationary sealing ring 100 is weakened. It was sometimes reduced.

  Further, even if the pressing plate 104 is tightened moderately, the tightening direction of the pressing plate 104 is the same as the direction of the reaction force from the rotary sealing ring 102 that is in sliding contact with the stationary sealing ring 100 being urged. Therefore, when the stationary sealing ring 100 is deformed due to a change with time and tightening of the holding plate 104 is weakened, the force in the direction of diameter reduction acting on the stationary sealing ring 100 is also weakened, and the sealing performance may be lowered.

  This invention is made | formed in view of such a situation, and it aims at providing the mechanical seal which can maintain high sealing performance over a long period of time.

  The present invention includes a rotary seal ring fixed to a rotary shaft so as to be integrally rotatable, and a stationary seal surface arranged concentrically with the rotary seal ring and in which the rotary seal surface of the rotary seal ring is slidably in close contact. A stationary seal ring formed by annularly combining a plurality of arc-shaped divided bodies, and an elastic member for holding the stationary seal ring and for urging the stationary seal ring toward the rotary seal ring And an annular retainer biased toward the rotary seal ring together with the stationary seal ring, the retainer being fixed to the casing and axially extending with the stationary side seal surface of the stationary seal ring A retainer body having a flange portion with which the back surface on the opposite side is in contact, and the stationary sealing ring is clamped and clamped from the stationary sealing surface side toward the flange portion. A mechanical seal that seals a gap between the rotating shaft and the casing. The stationary seal ring abuts on the flange portion, and the rotary seal ring is attached to the rotary seal ring. A tapered surface that is inclined so as to gradually increase in diameter is formed, and a tapered surface that can be brought into contact with the tapered surface of the flange portion is formed on the back surface of the stationary seal ring, Between the taper surface formed in the said flange part and the taper surface formed in the said back surface, the cyclic | annular sealing member which consists of an elastic material which seals between these is arrange | positioned, It is characterized by the above-mentioned.

According to the mechanical seal having the above configuration, the flange portion that tightens the stationary seal ring is formed with a tapered surface that is inclined so as to gradually increase in diameter toward the rotary seal ring. Since the taper surface is formed in contact with the taper surface, when the stationary seal ring is clamped and pressed toward the flange portion by the pressing member, a force acts in the direction of reducing the diameter of the stationary seal ring. To do. Thereby, it is possible to prevent the butted surfaces of the respective divided bodies from being pressed in the circumferential direction and causing a gap in the butted surfaces. In addition, since the stationary seal ring is subjected to a force that reduces the diameter when pressed against the flange side, the same axial direction as the reaction force from the rotating seal ring that acts when the stationary seal ring is biased The diameter is reduced by this force. Therefore, even if tightening of the pressing member is reduced due to aging, due to the reaction force from the rotating sealing ring when the stationary sealing ring is urged, a force in the direction of reducing the diameter acts on the stationary sealing ring, It is possible to prevent a gap from occurring on the abutting surface of each divided body.
Furthermore, between the taper surface formed in the said flange part and the taper surface formed in the back surface of a stationary sealing ring mutually pressed by clamping of a pressing member, the cyclic | annular seal member which seals between these Therefore, even if there is a positional shift in the axial direction between adjacent divided bodies and a step is generated on the tapered surface of the stationary seal ring, the back surface of the stationary seal ring is caused by the step. A gap on the side can be prevented by a sealing member made of an elastic material. Also, the taper surface of the flange portion and the taper surface of the stationary seal ring are pressed against each other by the reaction force acting on the stationary seal ring from the rotating seal ring when the stationary seal ring is biased. Even if the tightening of the pressing member is lowered, the sealing member can be pressed and held between both surfaces by the reaction force when the stationary sealing ring is biased, and the sealing performance of the sealing member can be prevented from being lowered. .
As described above, according to the mechanical seal of the present invention, in the split-type stationary seal ring, it is possible to reliably prevent gaps between the respective divided bodies, and between the back surface of the stationary seal ring and the retainer. Since it is possible to reliably prevent a gap from occurring, high sealing performance can be maintained over a long period of time.

In the mechanical seal, the stationary seal ring may be formed in a shape in which a cross section along the axial direction is line symmetric with respect to a center line that bisects the stationary seal ring in the axial direction.
In this case, the stationary seal ring can be inverted in the axial direction, and the back side can be used as a stationary side sealing surface. For this reason, even if the stationary side sealing surface cannot be used for some reason, it is possible to take an emergency measure such as using the back side as the stationary side sealing surface.

  In the mechanical seal, it is preferable that the seal member is provided at a position that substantially coincides with the stationary-side seal surface in the radial direction. In this case, the seal member is directly subjected to a reaction force from the rotary seal ring. It can be provided at a position that substantially coincides with the acting stationary seal surface in the radial direction. Thereby, a sealing member can be reliably pressed between the taper surface formed in the flange part, and the taper surface formed in the back surface of a stationary sealing ring, and both can be made to contact | adhere.

  According to the present invention, high sealing performance can be maintained over a long period of time.

It is sectional drawing of the mechanical seal which concerns on one Embodiment of this invention. It is an external view when a stationary seal ring is seen from the axial front. It is the fragmentary sectional view which expanded the stationary sealing ring in FIG. It is principal part sectional drawing of the conventional mechanical seal.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a mechanical seal according to an embodiment of the present invention.
In FIG. 1, a mechanical seal 1 is attached to a pump used in a water treatment facility such as a water and sewage system, and a pump case C of the pump and a pump shaft disposed through an opening c1 of the pump case C. The gap between S is sealed.
The mechanical seal 1 includes a rotary seal ring 2 fixed to a pump shaft S as a rotary shaft so as to be integrally rotatable, a stationary seal ring 3 in which a seal surface 2a of the rotary seal ring 2 is slidably in close contact, And a spring retainer 4 holding the sealing ring 3.

The rotary seal ring 2 is fixed to the pump shaft S through a stopper ring 5 so as to be integrally rotatable. The stopper ring 5 is capable of rotating integrally with the pump shaft S by tightening a fixing screw 6 screwed into a screw hole 5a formed so as to penetrate in the radial direction toward the pump shaft S, and It is fixed so that it does not move in the axial direction.
The rotary seal ring 2 is disposed on the stopper ring 5 on the axial pump case C side. A hole 2b into which a stopper pin 7 protruding from the end surface of the stopper ring 5 is inserted is formed on the end surface of the rotary seal ring 2 on the stopper ring 5 side. The rotary sealing ring 2 is connected to the stopper ring 5 by the stopper pin 7 so as to be integrally rotatable, and is rotatable integrally with the pump shaft S.
An O-ring 8 that seals between the inner peripheral surface of the rotary seal ring 2 and the outer peripheral surface of the pump shaft S is disposed on the inner peripheral side of the rotary seal ring 2.
Further, the sealing surface 2a of the rotary seal ring 2 exposes an annular hard layer 9 formed on the end surface of the rotary seal ring 2 by thermal spraying a material harder than the stationary seal ring 3, for example, ceramics such as alumina. It is configured by letting.

The spring retainer 4 is inserted into the opening c1 of the pump case C so as to be movable in the axial direction. The spring retainer 4 holds the stationary seal ring 3 and urges the stationary seal ring 3 toward the rotary seal ring 2. Holding.
The spring retainer 4 includes a retainer main body 11 and an annular pressing plate 12. The retainer body 11 is disposed on the outer peripheral side of the pump shaft S and is inserted into the opening c1 of the pump case C, and an end portion of the tubular portion 11a located on the axially outer side of the pump case C. And an annular flange portion 11b that holds the stationary sealing ring 3 with the presser plate 12.

In the opening c1 of the pump case C, a sleeve 13 having an annular plate 13a covering the periphery of the edge of the opening c1 on the outer surface c2 of the pump case C is fitted into the inner peripheral surface of the opening c1. The sleeve 13 is fixed to the pump case C by fixing the annular plate 13 a so as to be in close contact with the outer surface c <b> 2 by the bolt 14. An O-ring 15 for sealing between the sleeve 13 and the pump case C is disposed on the annular plate 13a.
The cylindrical portion 11a of the retainer body 11 is inserted through the sleeve 13 so as to be movable in the axial direction at the opening c1. An O-ring 16 for sealing the outer peripheral surface of the cylindrical portion 11a and the inner peripheral surface of the sleeve 13 is disposed on the outer peripheral surface side of the cylindrical portion 11a.

  A hole 11 b 1 for holding the spring 10 is formed in the flange portion 11 b of the retainer body 11. The axial direction of the spring 10 is held in parallel with the pump shaft S by the hole 11b1. The spring 10 has one end surface in contact with the annular plate 13 a and the other end surface in contact with the spring receiving member 18. The position of the spring receiving member 18 in the axial direction can be adjusted by an adjusting bolt 17 fixed to the holding plate 12, and the spring 10 is elastically compressed in the axial direction by the spring receiving member 18. Yes. Accordingly, the spring 10 urges the spring retainer 4 toward the rotary seal ring 2 together with the stationary seal ring 3 held by the spring retainer 4.

  The flange portion 11b is formed with a flushing flow path 19 that communicates the outer peripheral surface side and the inner peripheral surface side of the flange portion 11b. The flushing channel 19 is provided to introduce a flushing fluid for cleaning and cooling the inner peripheral surface of the stationary seal ring 3 from the outside of the retainer body 11 toward the inner peripheral surface. .

  The holding plate 12 is fixed to the flange portion 11b by a bolt 20, and holds the stationary seal ring 3 by clamping and sandwiching the stationary seal ring 3 with the flange portion 11b.

The stationary seal ring 3 held by the spring retainer 4 is a member formed mainly of carbon or other material. The stationary seal ring 3 is disposed concentrically with the rotary seal ring 2 and has a seal surface 3a in which the seal surface 2a of the rotary seal ring 2 is slidably in close contact.
FIG. 2 is an external view of the stationary seal ring 3 when viewed from the front in the axial direction. As shown in FIG. 2, the stationary sealing ring 3 is configured by combining two arc-shaped divided bodies 3b in an annular shape.
The stationary seal ring 3 is held by the spring retainer 4 in a state where the two divided bodies 3b are combined in an annular shape, and is urged toward the rotary seal ring 2 in close contact with the rotary seal ring 2. .

FIG. 3 is an enlarged partial sectional view of the stationary sealing ring 3 in FIG. As shown in the figure, the stationary seal ring 3 is directed from the outer peripheral surface side of the stationary seal ring 3 toward the axial front end side (both the seal surface 3a side and the back side opposite to the seal surface 3a in the axial direction). The outer tapered surface 3c, which is gradually reduced in diameter, and the inner tapered surface 3d, whose diameter is gradually increased from the inner peripheral surface side of the stationary sealing ring 3 toward the axial front end side (same as above), are formed on both sides thereof. Has been.
The outer tapered surface 3c and the inner tapered surface 3d are formed with substantially the same dimensions on both sides. For this reason, the stationary sealing ring 3 is formed in a shape in which a contour shape in a cross section (longitudinal cut surface) along the axial direction is substantially line symmetrical with respect to a center line that bisects the stationary sealing ring 3 in the axial direction. Has been.

The above-described seal surface 3a is formed at the tip of the stationary seal ring 3 where the outer tapered surface 3c formed on the rotary seal ring 2 side and the inner tapered surface 3d are connected. The seal surface 3a is in close contact with the seal surface 2a of the rotary seal ring 2 by surface contact with a constant width dimension in the radial direction.
The tip of the stationary seal ring 3 where the outer taper surface 3c and the inner taper surface 3d on the seal surface 3a side are connected is sharp when the stationary seal ring 3 is formed, with respect to the seal surface 2a. The seal surface 3a that can come into surface contact is not formed. Before being used as a mechanical seal, the stationary seal ring 3 is pressed against the seal surface 2a of the rotary seal ring 2 at a pressure higher than a normally urged pressure while being incorporated in the mechanical seal 1. The seal surface 3a is formed by applying a contact (performing a baking process). As a result, even if a step or the like is generated at the abutting portion between the divided bodies 3b constituting the stationary seal ring 3, a flat seal surface 3a having no step is formed after baking. However, even after baking, a step may remain in other portions of the outer tapered surface 3c and the inner tapered surface 3d other than the seal surface 3a that are not baked.

A pressing plate 12 that holds the stationary sealing ring 3 between the flange portion 11b and the outer tapered surface 3c on the seal surface 3a side is in contact with the outer tapered surface 3c.
On the other hand, the taper surface 11b2 of the flange portion 11b is in contact with the outer taper surface 3c formed on the back surface of the stationary seal ring 3 opposite to the seal surface 3a in the axial direction.
The tapered surface 11b2 is formed in the flange portion 11b so as to be inclined so as to gradually increase in diameter toward the rotary sealing ring 2.
The outer tapered surface 3c on the back surface side of the stationary seal ring 3 is formed so as to be able to contact with the tapered surface 11b2 of the flange portion 11b.

Further, an O-ring 30 is disposed between the outer tapered surface 3c on the back side and the tapered surface 11b2 of the flange portion 11b.
The O-ring 30 is formed using an elastic material such as butyl rubber, and is disposed in an annular groove 31 formed in the outer tapered surface 3c on the back side. The annular groove 31 is provided at a position substantially coinciding with the seal surface 3a in the radial direction. Therefore, the O-ring 30 disposed in the annular groove 31 is also disposed at the same position.

  The O-ring 30 is elastically compressed in a state where the outer taper surface 3c on the back surface side and the taper surface 11b2 of the flange portion 11b are in contact, and the inner surface of the annular groove 31 and the taper surface of the flange portion 11b. 11b2 is in close contact with and seals between the outer tapered surface 3c on the back side and the tapered surface 11b2 of the flange portion 11b.

  According to the mechanical seal 1 of the present embodiment configured as described above, a tapered surface 11b2 that is inclined so as to gradually increase in diameter toward the rotary seal ring 2 is formed on the flange portion 11b that tightens the stationary seal ring 3. The outer sealing surface 3c is formed on the back surface of the stationary seal ring 3 so as to be in contact with the tapered surface 11b2 of the flange portion 11b. When tightened and pressed, a force acts on the stationary seal ring 3 in the direction of reducing the diameter. Thereby, the abutting surfaces of the respective divided bodies 3b are pressed in the circumferential direction, and a gap can be prevented from being generated in the abutting surfaces of the respective divided bodies 3b. Further, since the stationary seal ring 3 is subjected to a force in the direction of being reduced in diameter by being pressed toward the flange portion 11b, the reaction force from the rotary seal ring 2 that acts when the stationary seal ring 3 is biased acts. The diameter is reduced by the same axial force. Therefore, even if the tightening of the presser plate 12 decreases due to the change over time, the reaction force from the rotary sealing ring 2 when the stationary sealing ring 3 is biased causes the stationary sealing ring 3 to have a force in the direction of reducing the diameter. Acts to prevent a gap from occurring on the abutting surface of each divided body 3b.

  Further, due to improper assembly or the like, a positional shift may occur in the axial direction between the adjacent divided bodies 3b, and a step may be formed on the outer tapered surface 3c on the back side. Here, in order to seal between the back surface of the stationary seal ring 3 and the taper surface 11b2 of the flange portion 11b, for example, when the liquid packing is used, the step difference depends on the application state of the liquid packing to the back surface. It may not be possible to prevent a gap from occurring on the back side of the stationary seal ring 3 due to the above.

In this regard, in the mechanical seal 1 of the present embodiment, the tapered surface 11b2 formed on the flange portion 11b and the outer tapered surface 3c formed on the back surface of the stationary seal ring 3 are pressed against each other by tightening the holding plate 12. Since an annular O-ring 30 that seals between them is disposed between the gaps, a gap is formed on the back side of the stationary sealing ring 3 due to the above-described step difference due to the self-sealing property of the O-ring 30. Can be prevented. Further, the taper surface 11b2 of the flange portion 11b and the outer taper surface 3c of the stationary seal ring 3 are mutually connected by a reaction force acting on the stationary seal ring 3 from the rotary seal ring 2 when the stationary seal ring 3 is biased. Even if the tightening of the presser plate 12 is lowered due to a change over time, the O-ring 30 can be pressed and held between both surfaces by the reaction force when the stationary sealing ring 3 is urged. It can prevent that the close_contact | adherence state of the ring 30 falls and a sealing performance falls.
As described above, according to the mechanical seal 1 of the present embodiment, in the split-type stationary seal ring 3, it is possible to reliably prevent a gap generated between the split bodies 3b, and maintain high sealing performance over a long period of time. be able to.

  Moreover, in the said embodiment, since the cross section along the axial direction of the stationary sealing ring 3 is formed in the shape which becomes line symmetrical with respect to the centerline which bisects the said stationary sealing ring 3 to an axial direction, The ring 3 can be inverted in the axial direction, and the back side can be used as a sealing surface. For this reason, even if the sealing surface 3a cannot be used for some reason, an emergency response such as using the back side of the sealing surface 3a as the sealing surface becomes possible.

  Further, in the mechanical seal 1, the O-ring 30 is provided at a position that substantially coincides with the seal surface 3 a in the radial direction, so that the O-ring 30 is directly sealed by a reaction force from the rotary seal ring 2. 3a can be provided at a position substantially coincident with the radial direction. Thereby, the O-ring 30 can be reliably pressed between the tapered surface 11b2 formed on the flange portion 11b and the outer tapered surface 3c formed on the back surface of the stationary seal ring 3, and can be brought into close contact with both.

The present invention is not limited to the above embodiments. In the said embodiment, although the case where the stationary sealing ring 3 was comprised by the two division bodies 3b was illustrated, you may comprise by more division bodies, such as 3 divisions and 4 divisions.
Moreover, the stationary sealing ring 3 of the said embodiment illustrates the case where the outline shape in the cross section along an axial direction is formed in the shape which becomes substantially line symmetrical with respect to the centerline which bisects the said stationary sealing ring 3 to an axial direction. However, the present invention is not limited to this, and the shape of the stationary seal ring 3 on the seal surface 3a side can be set regardless of the shape of the back surface side.

DESCRIPTION OF SYMBOLS 1 Mechanical seal 2 Rotating seal ring 2a Seal surface 3 Static seal ring 3a Seal surface 3b Split body 3c Outer taper surface 3d Inner taper surface 4 Spring retainer 10 Spring 11 Retainer main body 11a Tubular part 11b Flange part 11b1 Hole part 11b2 Tapered surface 12 Holding plate (holding member)
30 O-ring C Pump case (casing)
S Pump shaft (rotary shaft)

Claims (3)

A rotating seal ring fixed to the rotating shaft so as to be integrally rotatable;
A stationary seal ring that is concentrically disposed on the rotary seal ring and has a stationary side seal surface in which the rotary side seal surface of the rotary seal ring is slidably in close contact, and a plurality of arcuate segments are combined in an annular shape. When,
An annular member that holds the stationary seal ring and holds an elastic member for biasing the stationary seal ring toward the rotary seal ring, and is biased toward the rotary seal ring together with the stationary seal ring A retainer, and
The retainer is fixed to a casing and has a retainer body having a flange portion in contact with a back surface on the opposite side in the axial direction of the stationary seal surface of the stationary seal ring, and the stationary seal from the stationary seal surface side. An annular pressing member holding the stationary sealing ring by tightening and holding the ring toward the flange portion, and
In a mechanical seal that seals a gap between the rotating shaft and the casing,
The flange portion is formed with a tapered surface that abuts against the stationary sealing ring and is inclined so as to gradually increase in diameter toward the rotating sealing ring.
On the back surface of the stationary seal ring, a tapered surface is formed that can be brought into contact with the tapered surface of the flange portion.
Between the taper surface formed in the said flange part and the taper surface formed in the said back surface, the cyclic | annular sealing member which consists of an elastic material which seals between these is arrange | positioned, The mechanical characterized by the above-mentioned. seal.   2. The mechanical seal according to claim 1, wherein the stationary seal ring has a cross section along the axial direction that is symmetrical with respect to a center line that bisects the stationary seal ring in the axial direction.   The mechanical seal according to claim 1, wherein the seal member is provided at a position that substantially coincides with the stationary-side seal surface in the radial direction.

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