JPH057978U - Seal ring for cryopump - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent leakage from the cut part and always expect excellent sealing performance. [Structure] A ring-shaped main body 40 having a cut portion 6 is formed, and the cut portion 6 has a stepped shape having seat surfaces 71 and 72 extending in the circumferential direction of the ring-shaped main body 40.
By engaging the seat surfaces 71 and 72 so that they face each other and inclining the seat surfaces 71 and 72 from the cut base end portion toward the cut tip end portion toward the cut start end side of the cut base end portion, Ring-shaped body 40
The ring-shaped body 40 is expanded in diameter when it is attached to the reciprocating member 2 so that the seat surfaces 71 and 72 are brought into close contact with each other.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a seal ring interposed between a reciprocating member which is freely reciprocally mounted inside a cylinder of a cryopump and a stationary side member facing the reciprocating member.

[0002]

[Prior Art]

 Generally, a cryopump of this type is disclosed, for example, in Japanese Utility Model Laid-Open No. 62-856, and as shown in FIGS. 8 and 9, for example, a piston B which is reciprocally mounted inside a cylinder A. A ring-shaped fitting groove C is formed on the outer periphery of the seal ring E, and the seal ring E is fitted into the fitting groove C via an O-ring D made of an elastic material. The seal ring E is pressed against the inner peripheral surface of the cylinder A to seal the gap between the outer peripheral surface of the piston B and the inner peripheral surface of the cylinder A. As shown in FIG. 8, it is formed by a ring-shaped main body G having a cut portion F for enabling the diameter expansion or the diameter reduction.

[0003]

[Problems to be solved by the device]

 By the way, as shown in FIG. 8, a conventional cut portion F formed on the ring-shaped main body G is a pair of vertical cut portions cut in the axial direction of the ring-shaped main body G at positions separated by a predetermined distance in the circumferential direction. F1 and F2 and horizontal cut portions F3 that are formed by connecting these vertical cut portions F1 and F2 and cut parallel to the upper and lower end surfaces of the seal ring E. The horizontal cut portion is a crank-shaped cut surface in a front view. The sheet surfaces formed on F3 are made to face each other and are sealed. However, since the cut portion F is formed by a cutter, the horizontal cut portion F3 is formed on the horizontal cut portion F3 forming the sheet surface. A gap S2 corresponding to the thickness of the teeth of the cutter used to form the tooth is formed. Therefore, the helium gas easily leaks from the high pressure side to the low pressure side through the gap S1 between the vertical cut portions F1 and F2 and the gap S2 formed in the horizontal cut portion F3, and the pump performance of the cryopump deteriorates accordingly. ..

The present invention has been developed in view of the above circumstances, and an object thereof is to provide a seal ring capable of always expecting excellent sealing performance by eliminating leakage from the cut portion. There is

[0005]

[Means for Solving the Problems]

 The present invention, however, has a seal interposed between the reciprocating member 2 which is reciprocally mounted in the cylinder 1 having the heat stage 13 and the stationary side members 1 and 11 facing the reciprocating member 2. The sheet comprises a ring-shaped main body 40 having a cut portion 6, and the cut portion 6 has a stepped shape having seat surfaces 71 and 72 extending in the circumferential direction of the ring-shaped main body 40. The surfaces 71 and 72 are meshed so that they face each other, and the seat surfaces 71 and 72 are inclined from the cut base end portion toward the cut tip end portion toward the cut start end side of the cut base end portion. It is something.

[0006]

[Action]

 According to the present invention, when the ring-shaped main body is attached to the reciprocating member or the stationary-side member, the diameter of the ring-shaped main body 40 expands so that the seat surfaces 71 and 72 are closely attached to each other, and the cut portion is formed. Is reliably sealed, and as the diameter of the ring-shaped main body 40 increases, both side portions of the ring-shaped main body 40 sandwiching the cut portion 6 are guided by the guide of the seat surfaces 71 and 72 which are in contact with each other. When the ring-shaped main body 40 is assembled to the reciprocating member, for example, when the reciprocating member reciprocates, the ring is moved. The ring-shaped main body 40 moves axially relative to the reciprocating member in which the ring-shaped main body 40 is assembled in a state of being in contact with the stationary side member, and the separating side of the ring-shaped main body 40 is the ring-shaped main body. Will be pressed against the 40 one of the upper and lower sides of the fitting groove for fitting a result, the is the ing to the respective sheet surfaces 71, 72 may further brought into close contact.

Therefore, the ring-shaped body 40 is supported on the outer circumference of one of the reciprocating member and the stationary side member, and the outer peripheral portion of the ring-shaped body 40 is brought into contact with the inner circumference of the other member to seal. In the case of the outer seal type, that is, when the outer peripheral portion of the ring-shaped body 40 is worn, the ring-shaped body 40 expands in diameter following this wear. The cut portion, in other words, the sheet surfaces 71 and 72 are in close contact with each other and can effectively seal.

When the ring-shaped main body 40 is supported on the inner circumference of one of the members and the inner peripheral portion of the ring-shaped main body 40 is brought into contact with the outer circumference of the other member for sealing, that is, inside In the case of a seal, when the inner peripheral portion of the ring-shaped body 40 is worn, the ring-shaped body 40 shrinks in diameter following this wear. By separating them from each other in the direction, even if the ring-shaped main body 40 is reduced in diameter until the pressing force between the seat surfaces 71 and 72 is reduced until these separated states disappear, each of these sheets is pressed. The surfaces 71 and 72 do not separate from each other, and when the reciprocating member reciprocates, the ring-shaped main body 40 is attached to the ring-shaped main body 40 by, for example, relative movement with respect to the reciprocating member. Side Since the seat surfaces 71 and 72 are pressed against one of the upper and lower surfaces of the fitting groove into which the ring-shaped body 40 is fitted and the seat surfaces 71 and 72 are in close contact with each other, it is possible to effectively seal even in this case. ..

[0009]

【Example】

 In the cryopump shown in FIG. 7, a displacer 2a and a slack piston 2b are reciprocally mounted inside a cylinder 1, while a cylinder head 11 is provided with a guide / discharge passage 3 which communicates with the inside of the cylinder 1. A high pressure gas pipe 35 and a low pressure gas pipe 36 extending from a helium compression unit 34 are connected to the guide / discharge passage 3 via a switching valve device 33 including a high pressure on / off valve 31 and a low pressure on / off valve 32. ..

In the embodiment of FIG. 7, the displacer 2a and the slack piston 2b constitute the reciprocating member 2, and the cylinder 1 and the cylinder head 11 assembled to the cylinder 1 constitute the stationary member. is doing.

Further, the upper chamber 12 in the cylinder 1 is connected to the guide / exhaust passage 3 via a capillary 37, and is also connected to the low pressure gas pipe 36 via a variable bleed 38, so that the upper chamber 12 is connected. 12 is maintained at an intermediate pressure, a disintegrator 2a is internally provided with a storage cooler 20 made of copper or lead, and the heat stage 13 of the cylinder 1 is housed in a vacuum container 100. Therefore, by repeating the reversible opening / closing operation of the high-pressure and low-pressure on-off valves 31 and 32 constituting the switching valve device 33, introduction of high-pressure gas into the cylinder 1 and low-pressure gas By repeatedly performing exhausting and reciprocating the reciprocating member 2 in the cylinder 1, an extremely low temperature is obtained in the heat stage 13 of the cylinder 1.

In the cryopump having the above structure, between the outer peripheral wall of the displacer 2a and the inner peripheral wall of the cylinder 1, between the outer peripheral wall of the slack piston 2b and the inner peripheral wall of the cylinder 1, and The first to third seal rings 4a, 4b, 4c according to the present invention are respectively installed at three locations between the inner peripheral wall of the slack piston 2b and the outer peripheral wall of the cylinder head 11, and the respective seal rings are provided. The different pressure spaces in the cylinder 1 are airtightly sealed by 4a, 4b and 4c.

Specifically, as shown in FIGS. 2 and 3, the outer peripheral surface of the upper end portion of the displacer 2a, the outer peripheral surface of the lower end portion of the slack piston 2b, and the inner peripheral surface of the upper end portion each have a U-shaped cross section. The fitting grooves 5a, 5b, 5c are provided around the fitting grooves 5a, 5b, 5c, and the first to third O-rings 6a, 6b, 6c made of an elastic material are provided in the fitting grooves 5a, 5b, 5c. The third seal rings 4a, 4b, 4c are fitted and the outer peripheral surfaces of the first and second seal rings 4a, 4b are attached to the inner peripheral surface of the cylinder 1, and the inner peripheral surface of the third seal ring 4c is attached. Since the outer peripheral surface of the cylinder head 11 is brought into pressure contact with each other, in the embodiment shown in the drawings, the groove width of each of the fitting grooves 5a, 5b, 5c is set to that of the seal rings 4a, 4b, 4c. Formed slightly larger than the width.

Next, the seal rings 4a, 4b, 4c attached to the fitting grooves 5a, 5b, 5c will be described below.

The seal rings 4a, 4b, 4c are composed of a ring-shaped main body 40 made of a solid lubricating material, and a cut portion 6 that allows the ring-shaped main body 40 to be expanded or reduced in diameter. Is provided.

The cut portion 6 is formed in a stepped shape having seat surfaces 71, 72 extending in the circumferential direction of the ring-shaped main body 40. Specifically, as shown in FIG. , A pair of first and second vertical cut portions 61 and 62 whose cut surfaces extend in the axial direction of the ring-shaped main body 40 at positions separated by a predetermined distance in the circumferential direction, and a horizontal cut connecting these vertical cut portions 61 and 62. And the seat surfaces 71 and 72 extending in the circumferential direction of the ring-shaped main body 40 and facing each other are provided in the cut portion of the lateral cut portion 63, and the seat surfaces 71 and 72 are formed. That is, the cut base end portion is inclined toward the cut start end side from the cut base end portion toward the cut tip end portion.

That is, at the time of forming the horizontal cut portion 63, the horizontal cut portion 63 is moved from the first vertical cut portion 61 side toward the second vertical cut portion 62 side, and the upper side surface of the ring-shaped main body 40 is By inclining to the 41 side, as the ring-shaped main body 40 expands in diameter, both seat surfaces 71 and 72 come into contact with each other, and as shown in FIGS. By the guide, both sides 40a and 40b of the ring-shaped body 40 sandwiching the cut portion 6 are axially separated from each other.

Therefore, in the seal ring having the above structure, the seal rings 4a and 4b are attached to the first and second fitting grooves 5a and 5b as shown in FIG. The two fitting grooves 5a, 5b are fitted through the O-rings 6a, 6b. When the first and second fitting grooves 5a, 5b are fitted, the seal rings 4a, 4b are fitted. By expanding the diameter and bringing the sheet surfaces 71 and 72 into contact with each other as shown in FIG. 4, the gap S2 of the lateral cut portion 63 caused by the molding of the cut portion 6 is closed accordingly. Therefore, the cut portions 6 of the seal rings 4a and 4b are reliably sealed, and the sealing performance of the seal rings 4a and 4b is improved.

By the way, when the outer peripheral surfaces of the seal rings 4a, 4b wear due to the reciprocating motion of the reciprocating member 2, the elastic forces of the O-rings 6a, 6b expand the diameters of the seal rings 4a, 4b. However, due to this expanded diameter, the two seat surfaces 71, 72 are brought into closer contact with each other, and the sealing performance of the seal rings 4a, 4b is further improved. On the other hand, as shown in FIG. With this guide, both side portions 40a and 40b of the ring-shaped main body 40 sandwiching the cut portion 6 are axially separated from each other.

Thus, when the reciprocating member 2 reciprocates, for example, as the reciprocating member 2 moves downward, relative movement of the seal rings 4 a and 4 b with respect to the reciprocating member 2 in the axial direction. As a result, the upper side surface 41 of the upwardly displaced portion 40a of the ring-shaped body 40 is pressed against the upper side surfaces of the upper and lower opposite side surfaces of the fitting grooves 5a and 5b, respectively. Is further pressed in a direction in which they closely contact each other, so that the contact between the two sheet surfaces 71 and 72 further increases, so that the sealing performance by the seal rings 4a and 4b is further improved.

Incidentally, when the seal rings 4a, 4b are fitted into the first and second fitting grooves 5a, 5b, the diameters of the seal rings 4a, 4b are expanded so that both seat surfaces 71, 72 are formed. With this guide, both side portions 40a and 40b of the ring-shaped body 40 that sandwich the cut portion 6 may be set so as to be separated from each other in the axial direction.

On the other hand, in the seal ring having the above structure, the third seal ring 4c is attached to the third fitting groove 5c by fitting it into the third fitting groove 5c via the O-ring 6c. However, the diameter of the third seal ring 4c is expanded in consideration of the diameter reduction due to the wear of the inner peripheral surface of the seal ring, and when the third seal ring 4c is interposed between the slack piston 2b and the cylinder head 11. The both side portions 40a and 40b of the ring-shaped body 40 sandwiching the cut portion 6 are attached so that they are separated from each other by a certain amount T in the axial direction as shown in FIG. As the diameter of the third seal ring 4c increases, the degree of adhesion between the seat surfaces 71 and 72 increases, so that the sealing performance of the third seal ring 4c is improved.

By the way, when the inner peripheral surface of the third seal ring 4c is worn due to the reciprocating movement of the slack piston 2b, the diameter of the third seal ring 4c is reduced, and the adhesion between the seat surfaces 71 and 72 is reduced. Although it is lowered, since both side portions 40a and 40b sandwiching the cut portion 6 are axially separated from each other, when the slack piston 2b moves back and forth, the third seal ring 4c with respect to the slack piston 2b moves. Due to the relative movement in the axial direction, the upper and lower opposite side surfaces of the fitting groove 5c, which face each other, are located on the upper side surface of the upwardly displaced portion 40a of the ring-shaped main body 40 or the lower portion of the downwardly displaced portion 40b. By abutting against the side surface and pressing the sheet surfaces 71, 72 in contact with each other in a direction of further closely adhering the sheet surfaces 71, 72, the sheet surfaces 71, 72 are more firmly adhered. Therefore, the sealing performance of the seal ring 4C does not deteriorate.

[0024]

[Effect of the device]

 As described above, the present invention comprises the ring-shaped body 40 having the cut portion 6, and the cut portion 6 has a stepped shape having seat surfaces 71, 72 extending in the circumferential direction of the ring-shaped body 40. By engaging the sheet surfaces 71 and 72 so that they face each other, and inclining the sheet surfaces 71 and 72 from the cut base end portion toward the cut tip end portion toward the cut start end side of the cut base end portion, When the diameter of the ring-shaped main body is expanded and attached to the reciprocating member or the stationary member, the sheet surfaces 71 and 72 are in close contact with each other, and the cut portion can be reliably sealed. As the diameter of the ring-shaped main body 40 is expanded, the both sides of the ring-shaped main body 40 sandwiching the cut portion 6 are axially separated from each other by the guide of the contacting seat surfaces 71 and 72. Therefore, the ring-shaped body 40 is fitted in, for example, the fitting groove of the reciprocating member, and both side portions of the ring-shaped body 40 sandwiching the cut portion 6 are axially separated from each other. When the reciprocating member reciprocates, the ring-shaped main body 40 is axially moved relative to the reciprocating member to which the ring-shaped main body 40 is assembled. By being pressed against one of the upper and lower side surfaces of the mating groove, it is possible to further increase the degree of contact between the two sheet surfaces 71, 72.

Accordingly, one of the reciprocating member and the stationary member is fitted to the ring-shaped body 40 on the outer periphery of the member, and the outer peripheral portion of the ring-shaped body 40 is brought into contact with the inner periphery of the other member. In the case of sealing, not only the sealing performance is improved due to the close contact between the two seat surfaces 71 and 72, but also the expansion of the ring-shaped main body 40 due to the wear of the outer peripheral portion of the ring-shaped main body 40 causes the above-mentioned problem. As described above, the degree of adhesion between the sheet surfaces 71 and 72 is increased, and the sealing performance can be further improved.

Also, in the case where the ring-shaped body 40 is fitted to the inner circumference of one of the members and the inner circumference of the ring-shaped body 40 is brought into contact with the outer circumference of the other member for sealing. If the diameter of the ring-shaped main body 40 is expanded and both side portions of the ring-shaped main body 40 that sandwich the cut portion 6 are separated from each other in the axial direction, the sealing performance is improved by the close contact between the seat surfaces 71 and 72. Of course, the diameter of the ring-shaped body 40 is reduced due to the wear of the inner peripheral portion of the ring-shaped body 40 due to the forward and backward movement of the reciprocating member, so that the space between the seat surfaces 71 and 72 is reduced. Even if the pressing force of the ring-shaped main body 40 is reduced, the ring-shaped main body 40 is assembled by the relative movement of the ring-shaped main body 40 with respect to the reciprocating member. Both upper and lower part of the ditch The sheet is pressed against one of the side surfaces, and the degree of adhesion between the sheet surfaces 71 and 72 is increased by this pressing, so that the cut portion can be reliably sealed.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a seal ring.

FIG. 2 is an enlarged cross-sectional view of a main part of a cryopump provided with a seal ring.

FIG. 3 is an enlarged cross-sectional view of a main part of a cryopump provided with a seal ring.

FIG. 4 is an enlarged front view of a main part of a cryopump provided with a seal ring.

FIG. 5 is an enlarged front view of a main part of a cryopump with a seal ring attached.

FIG. 6 is an enlarged front view of a main part of a cryopump provided with a seal ring.

FIG. 7 is a schematic sectional view of a cryopump.

FIG. 8 is an enlarged front view of a main part of a cryopump in which a conventional seal ring is assembled.

FIG. 9 is an enlarged cross-sectional view of a main part of a cryopump in which a conventional seal ring is assembled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 cylinder 11 cylinder head 13 heat stage 2 reciprocating member 40 ring-shaped body 6 cut portion 71 seat surface 72 seat surface

Claims (1)

Claims for utility model registration: 1. A reciprocating member 2 which is reciprocally mounted inside a cylinder 1 having a heat stage 13, and stationary side members 1 and 11 which face the reciprocating member 2. A seal ring interposed between the ring-shaped body 40 and the ring-shaped body 40 having the cut portion 6.
0 has a stepped shape having seat surfaces 71 and 72 extending in the circumferential direction, and meshes as the seat surfaces 71 and 72 face each other, and the seat surfaces 71 and 72 are cut from the cut base end portion to the cut tip end portion. A seal ring for a cryopump, which is inclined toward the cut start end side in the cut base end portion.