JP2959556B1 - Seal mechanism, refrigerator and turbo compressor provided with the seal mechanism - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To improve initial sealing performance and maintain the sealing performance for a long time in a non-contact type sealing mechanism. SOLUTION: A clearance seal (12) is provided on an outer peripheral surface of a piston (11). On both sides of the clearance seal (12), flat portions (55) having a predetermined initial clearance s1 and facing the inner wall surface of the cylinder (6) and having a flat cross section are formed. Between the flat portions (55, 55), there is formed a concave portion (57) having a cubic curved cross section toward the inside. When the clearance increases due to wear of the clearance seal (12), the concave portion (57) increases the seal length with the increase in the area of the flat portion (55), so that the amount of fluid leakage is always constant. Is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a seal mechanism, and more particularly, to a non-contact type seal mechanism.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No.
Various sealing mechanisms are used in a refrigeration machine, a fluid machine, and the like disclosed in Japanese Patent Application Publication No. 80-80. Among these seal mechanisms, a non-contact type seal mechanism is known as a seal mechanism for sealing between a movable portion and a stationary portion.

FIG. 11 shows an example of an expander (300) using a clearance seal (301, 302) as a non-contact type sealing mechanism. A free displacer (306) is inserted into the cylinder (303) of the expander (300). The free displacer (306) divides the internal space of the cylinder (303) into an expansion space (304) and a working space (305). A regenerator (307) is provided inside the free displacer (306), and the regenerator (307) communicates with the expansion space (304) and the working space (305). A coil spring (308) elastically supporting the free displacer (306) in a reciprocating manner is provided in the working space (305). Working space (305) is connected pipe
(309), it is connected to a compressor not shown.
Then, a periodically fluctuating gas pressure is supplied from the compressor, and the free displacer (306) reciprocates in the cylinder (303). As a result, the working fluid expands in the expansion space (304), and the heat station (310) fixed to the tip of the cylinder (303) is cooled to an extremely low temperature.

The base end (311) of the free displacer (306)
A ring-shaped first clearance seal (301) and a second clearance seal (302) are fitted into the distal end (312), respectively. Each clearance seal (301), (302)
Is opposed to the inner surface of the cylinder (303) with a predetermined gap, that is, a predetermined clearance.
The sealing surface of each clearance seal (301, 302) is formed on a smooth circumferential surface without irregularities.

The axial length and clearance length of the seal surface of each clearance seal (301, 302) are set in consideration of both the reciprocal movement resistance of the free displacer (306) and the amount of working fluid leakage. .

[0006]

By the way, the clearance surfaces of the clearance seals (301) and (302) gradually wear due to direct contact with the cylinder (303). Therefore, after long-term use, the clearance length becomes longer than the initial clearance length. As a result, even if the clearance seal exhibits sufficient sealing performance before wear, the sealing performance cannot be maintained over a long period of use, and the amount of fluid leakage increases.

In order to exhibit sufficient sealing performance even after long-term use, it is conceivable to set a longer sealing length. FIG. 12 shows the axial length of the first clearance seal (301) in the expander (300).
That is, a form in which the seal length is increased is shown. However, when the seal length of the clearance seal (301) is increased, the resistance of the free displacer (306) increases, and smooth reciprocating movement becomes difficult. Therefore, if the specification of the clearance seal (301) is selected so as to exhibit sufficient sealing performance after abrasion, the initial performance of the expander is reduced.

FIG. 13 shows a change in refrigeration capacity of a Stirling refrigerator having a conventional clearance seal. The horizontal axis shows the clearance length (μm), and the vertical axis shows the refrigeration capacity (the ratio to the reference capacity). Since the clearance seal wears over time, the clearance length increases over time. Therefore, it can be said that the horizontal axis indicates the passage of time. The chain line in the drawing shows a clearance seal with a seal length of 30 mm, and the one-dot chain line shows a clearance seal with a seal length of 12 mm. As is clear from FIG.
The initial performance of the 2 mm clearance seal is high due to the low resistance of the initial displacer, but the performance rapidly decreases as the clearance length increases. On the other hand, a clearance seal having a seal length of 30 mm has a relatively small decrease in performance due to an increase in clearance, but has a low initial performance due to a large resistance of an initial displacer.

As described above, in the conventional clearance seal, if the clearance length is sufficiently ensured to reduce the resistance of the displacer to reciprocal movement, the sealing performance is remarkably deteriorated after abrasion. On the other hand, if the clearance length is shortened or the seal length is lengthened to ensure sufficient sealing performance even after abrasion, the resistance of the displacer to reciprocal movement increases and the initial performance decreases. For this reason, it has been considered difficult to increase the initial performance and maintain the initial performance for a long period of time.

[0010] The present invention has been made in view of the above points, and an object thereof is to improve the initial sealing performance of a non-contact type sealing mechanism,
The purpose is to maintain the sealing performance for a long time.

[0011]

In order to achieve the above-mentioned object, the present invention provides a method of forming a groove in a clearance seal so that the seal length is short in an initial state and is long after abrasion. did.

Specifically, the means taken by the first invention are:
A first member having a first facing surface, and a second member having a second facing surface facing the first facing surface with a gap therebetween
(6,72) and the first member (11,102) so as to have a sealing surface facing the second facing surface at a predetermined interval (s1).
The clearance seal (12,
104), the first member (11, 102) and the second member
(6, 72) performs relative movement, while the seal mechanism for sealing between the first opposing surface and the second opposing surface includes the second seal on the seal surface of the clearance seal (12, 104). The main sealing surface (55, 105) facing the predetermined opposing surface with a predetermined initial clearance, and the auxiliary sealing surface (57, 60, 106) opposing the second opposing surface with a clearance larger than the initial clearance. It has been formed.

According to the above, the gap between the first opposing surface of the first member and the second opposing surface of the second member performing relative movement is
Sealed with a clearance seal. In the initial state before the clearance seal wears, the sealing action is performed mainly on the main seal surface. On the other hand, when used for a long period of time, the main sealing surface gradually wears, and a part of the sub-sealing surface also performs the sealing action. Therefore, when the clearance seal wears, the clearance length increases, but the seal length increases because a part of the sub-seal surface performs a sealing action. Here, the seal length means the length of a portion of the seal surface that actually contributes to the sealing action. Therefore, the increase in the leakage amount due to the increase in the clearance length is offset by the decrease in the leakage amount due to the increase in the clearance length, and as a result, the leakage amount of the fluid becomes constant. In this way, the initial sealing performance is maintained for a long time.

According to a second aspect of the present invention, in the first aspect, a groove (57, 60, 106) is formed on a sealing surface of the clearance seal (12, 104), and a main seal of the clearance seal (12, 104) is formed. The surface is constituted by the non-groove portions (55, 105), while the auxiliary seal surface of the clearance seal (12, 104) is constituted by the grooves (57, 60, 106).

According to the above, the main sealing surface and the sub-sealing surface are easily manufactured.

According to a third aspect of the present invention, in the second aspect of the invention, the grooves (57, 60, 106) on the sealing surface of the clearance seal (12, 104) are formed so that the amount of fluid leakage is equal to that before the sealing surface is worn. It is formed so as to have substantially the same amount after a predetermined amount of wear.

According to the above, the leakage amount of the fluid before and after the wear of the clearance seal becomes substantially the same, so that the initial sealing performance is reliably maintained.

According to a fourth aspect of the present invention, in the first aspect, the cross-sectional shape of the sealing surface of the clearance seal (12, 104) is flat and parallel to the second facing surface of the second member (6, 72). Part (55) and the first member (11,102) from the flat part (55).
And a main sealing surface of the clearance seal (12, 104), the flat portion (55).
While the clearance seal (12,104)
The sub-sealing surface of (1) is constituted by the inclined portion (61).

According to the above, the main seal surface and the sub seal surface are easily manufactured.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the inclined portion (61) of the sealing surface of the clearance seal (12, 104) has a fluid leakage amount before and after the seal surface is worn. It is to be formed so as to have substantially the same amount after the constant wear.

According to the above, the leakage amount of the fluid before and after the wear of the clearance seal becomes substantially the same, so that the initial sealing performance is reliably maintained.

The measures taken by the sixth invention are as follows.
In any one of the inventions, the clearance seal (12, 10
4) is based on one or more of polytetrafluoroethylene, polyimide, polyamideimide or polyacetal, and is filled with one or more of carbon, carbon fiber, bronze or molybdenum disulfide It is made of a resin material as a material.

From the above, the clearance seal is made of a particularly suitable material.

Means taken by the seventh invention is a cylinder (6)
The piston (11) reciprocates in a predetermined cycle to compress the working gas to generate a predetermined cycle gas pressure in the cylinder (6), and the gas pressure is supplied. So that the cylinder (6) of the compressor (1)
The displacer (37) reciprocates in the cylinder (31) by the above gas pressure, and the working gas expands in the expansion space (35), so that the heat station (32)
A refrigerating machine having an expander (2) for generating cold, wherein the piston (11) and the cylinder (6) of the compressor (1) are used as a first member and a second member, respectively, The present invention provides a seal mechanism according to any one of the first to sixth aspects.

According to the above-mentioned matter, the space between the piston and the cylinder of the compressor is sealed by the seal mechanism according to the first to sixth aspects of the present invention, so that the performance of the compressor is maintained at a high level for a long time. become.

According to an eighth aspect of the present invention, a cylinder (6)
The piston (11) reciprocates in a predetermined cycle to compress the working gas to generate a predetermined cycle gas pressure in the cylinder (6), and the gas pressure is supplied. So that the cylinder (6) of the compressor (1)
The displacer (37) reciprocates in the cylinder (31) by the above gas pressure, and the working gas expands in the expansion space (35), so that the heat station (32)
And a displacer (37) and a cylinder of the expander (2).
(31) as the first member and the second member, respectively,
The present invention provides a seal mechanism according to any one of the first to sixth aspects.

According to the above, the seal between the displacer and the cylinder of the expander is sealed by the seal mechanism according to the first to sixth aspects, so that the performance of the expander is maintained at a high level for a long time. become.

The means taken by the ninth invention is that the casing (7
1) Inside the motor chamber (75) and impeller chamber by the partition walls (72, 73)
(74, 76), the impeller (78, 79) connected to the drive shaft (77) rotates in the impeller chamber (74, 76) to compress the refrigerant by the turbo compressor, The seal mechanism according to the first to sixth aspects of the present invention is provided by using the drive shaft (77) and the partition walls (72, 73) as a first member and a second member, respectively.

According to the above, since the space between the drive shaft and the partition is sealed by the seal mechanism according to the first to sixth aspects of the present invention, the fluid leakage between the impeller chamber and the motor chamber becomes constant, Performance will be maintained over time.

The grooves on the sealing surface of the clearance seals (12, 104) are rectangular grooves (57a, 5a) having a rectangular cross section of a predetermined depth.
7b).

According to the above, the groove of the sealing surface can be easily manufactured.

The rectangular groove (57a, 57b) of the clearance seal (12, 104) has an initial clearance h1, a length of the sealing surface L, a depth of the rectangular groove (57a, 57b) h2, a rectangular groove (57).
(57a, 57b) the length of when the ^{L1, h1 3 / (L-} L
1) It may be formed so as to satisfy the relationship of ≒ (h1 + h2) ³ / L.

According to the above, a groove shape corresponding to the fluid leakage characteristics is realized.

The rectangular groove of the clearance seal (12, 104) may be constituted by a single rectangular groove (57a).

According to the above, a rectangular groove on the sealing surface can be obtained with a simple structure.

The rectangular groove of the clearance seal (12, 104) may be constituted by a plurality of rectangular grooves (57b).

According to the above, a rectangular groove on the sealing surface can be obtained with a simple structure.

The groove on the sealing surface of the clearance seal (12, 104) may be constituted by a V-shaped groove (60) having a V-shaped cross section.

According to the above, a groove on the sealing surface can be obtained with a simple structure.

Further, the groove on the sealing surface of the clearance seal (12, 104) may be constituted by a curved groove (57) formed by a cubic curve with a concave section line.

According to the above, when the fluid flowing through the gap is laminar, the leakage amount is considered to be substantially proportional to the cube of the clearance and inversely proportional to the seal length. Will be obtained.

The first member (11,102) or the second member (6,72)
May be configured to perform a linear reciprocating motion.

The first member (11,102) or the second member (6,72)
May be configured to perform a rotational movement.

[0044]

According to the first aspect of the present invention, since the main seal surface and the sub seal surface are provided on the seal surface of the clearance seal, the length of the seal increases with the wear of the clearance seal. An increase in the amount of leakage due to an increase in length can be suppressed, and the amount of leakage can be kept constant. Therefore, the initial sealing performance can be maintained for a long time.

According to the second or fourth aspect, the main seal surface and the sub seal surface can be easily manufactured.

According to the third or fifth aspect of the present invention, the amount of fluid leakage before and after the wear of the clearance seal is substantially the same, so that the initial sealing performance can be reliably maintained.

According to the sixth aspect, the clearance seal can be made of a particularly suitable material, and the sealing performance can be improved.

According to the seventh aspect, since the seal mechanism according to the first to sixth aspects is provided between the piston and the cylinder, the performance of the compressor can be maintained for a long time, and Performance can be improved.

According to the eighth aspect, since the seal mechanism according to the first to sixth aspects is provided between the displacer and the cylinder, the performance of the expander can be maintained for a long time, and Performance can be improved.

According to the ninth aspect, the seal mechanism according to the first to sixth aspects is provided between the drive shaft and the partition wall.
It is possible to stably suppress the refrigerant leakage between the impeller chamber and the motor chamber for a long period of time, and to improve the performance of the turbo compressor.

[0051]

Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Structure of Stirling Refrigerator- FIG. 1 shows a vibrating compressor (1) of a Stirling refrigerator having a seal mechanism according to the present embodiment. The compressor (1) is a double-piston type compressor having two pistons (11) and (11) arranged vertically symmetrically, and has a clearance seal (1) between the piston (11) and the cylinder (6). 12) is provided. FIG. 2 shows an expander (2) of the Stirling refrigerator. The expander (2) is a free displacer type expander in which the free displacer (37) reciprocates in the cylinder (31), and includes a free displacer (37) and a cylinder (31).
Clearance seals (52) and (53) are provided between the two.

-Overall Configuration of Compressor (1) First, the overall configuration of the compressor (1) will be described with reference to FIG. The compressor (1) has a closed cylindrical housing (3) extending in the vertical direction. The housing (3) is composed of a cylindrical wall (4) extending in the vertical direction, and disk walls (5, 5) for hermetically closing both ends of the cylindrical wall (4). housing
(3) has a block extending in the axial direction of the housing (3).
(9) is fixed. One cylinder extending vertically, with the center of the block (9) penetrated and both ends open
(6) is formed. The central portion of the cylinder (6) extends radially outward, and has a disk-shaped flange portion (7) orthogonal to the center line of the cylinder (6). The outer peripheral portion of the flange portion (7) extends in the up-down direction concentrically with the cylinder (6) to form a cylindrical fitting portion (8). The outer peripheral surface of the fitting part (8) is attached to a predetermined position on the inner peripheral surface of the cylindrical wall part (4), and the block (9)
Is fixed to the housing (3). A cylindrical yoke member (10) is fitted on the outer peripheral surface of the cylinder (6). The block (9) and the yoke member (10) are formed from a magnetic material such as pure iron, and constitute a yoke (yoke).

In the cylinder (6), a pair of upper and lower cylindrical pistons (11), (11) having a bottom is inserted so as to be reciprocally movable with their distal ends facing each other. And the cylinder
A compression space (13) for compressing the working fluid is defined by (6) and both pistons (11), (11). Piston (11)
A clearance seal (12), which is a feature of the present embodiment, is fixed to the outer peripheral surface of. The clearance seal
The detailed configuration of (12) will be described later.

The block (9) is provided with a gas passage (14) extending radially through the block (9) from the inside of the cylinder (6) to the outer peripheral surface of the fitting portion (8). The inner end of the gas passage (14) is always in communication with the compression space (13). On the other hand, a through hole (15) is formed in the cylindrical wall (4) of the housing (3) at a position corresponding to the outer end of the gas passage (14). And expander
A connection pipe (16) connected to (2) penetrates the through hole (15) and is connected to the gas passage (14).

The upper and lower pistons (11) are provided with linear motors (17) for driving the respective pistons (11). The linear motor (17) has a driving magnet (18) composed of an annular permanent magnet fitted on the outer peripheral surface of the yoke member (10),
It has a bobbin (21) fixed to the piston (11) and a drive coil (22) wound around the bobbin (21). The driving magnet (18) faces the fitting portion (8) with a predetermined gap between the driving magnet (18) and the fitting portion (8) of the block (9). With the driving magnet (18), the yoke member (10), the flange portion (7) and the fitting portion (8) are used as a yoke, and the outer peripheral surface of the driving magnet (18) and the inside of the fitting portion (8) are formed. A magnetic field (static magnetic field) of a predetermined strength is generated between the magnetic field and the peripheral surface. Each piston (11) has a flange portion (20) extending radially outward on the rear side, that is, on the disk wall (5) side. Cylindrical bobbin with bottom
(21) is integrally attached to the flange portion (20) on the bottom wall side. The bobbin (21) extends concentrically with the piston (11) toward the center of the cylinder (6), and its tip is disposed in a magnetic field between the driving magnet (18) and the fitting portion (8). ing.
A driving coil (22) (solenoid) composed of an electromagnetic coil is wound around the outside of the tip of the bobbin (21).
The movable part (19) of the linear motor (17) is constituted by the flange part (20) and the bobbin (21).

A current introducing terminal (23) penetrates through the disk wall (5) of the housing (3), and the current introducing terminal (23) is fixedly supported in an insulated state on the disk wall (5). . Drive coil
(22) is via a lead wire (24) and a current introduction terminal (23),
It is connected to a controller (not shown).

The controller is connected to a drive power supply (not shown) and supplies an alternating current from the drive power supply to each drive coil (22) in synchronization with the drive power supply. As a result, moving parts
(19) reciprocates at a predetermined cycle, and the pistons (11) integrated with the movable portion (19) reciprocate in opposite directions so as to come and go with each other at a predetermined cycle. Then, a predetermined period of gas pressure is generated in the compression space (13).

On the inner wall surface of the disk wall (5) of the compressor (1), a disk-shaped spring mounting member (25) is projected at a position on the axis of the piston (11). A spiral spring mounting groove (26) is formed on the outer periphery of the member (25). on the other hand,
A spring mounting member (27) is also fixed to the bottom surface of the piston (11),
A spiral spring mounting groove (28) is also formed on the outer periphery of the spring mounting member (27). Then, one end of the coil spring (29) is attached to the spring attachment groove (26) of the spring attachment member (25), and the other end is attached to the spring attachment groove (28) of the spring attachment member (27). (11) is elastically supported by a coil spring (29).

Next, the overall configuration of the expander (2) will be described with reference to FIG. The expander (2) has a cylindrical cylinder (31) extending in the left-right direction. The tip side (left side in FIG. 2) of the cylinder (31) is joined to the heat station (32). On the other hand, the base end side (the right side in FIG. 2) of the cylinder (31) is joined to the flange (33).

In the cylinder (31), a substantially cylindrical free displacer (37) that divides the internal space into an expansion space (35) on the distal side and an operating space (36) on the proximal side is reciprocally movable. Has been inserted. The inside of the free displacer (37) is filled with a regenerator material to form a regenerator (38) (a regenerative heat exchanger). The regenerator (38) is a free displacer (3
Communication hole (39) and base end (42) formed at the tip (48) of (7)
The communication hole (40) formed in the expansion space (35)
And the working space (36). The outer peripheral surface of the tip (48) of the free displacer (37) seals a gap between the free displacer (37) and the cylinder (31) to expand the expansion space.
A first clearance seal (52) for maintaining the low pressure of (35) is fitted. On the other hand, on the outer peripheral surface of the base end (42) of the free displacer (37), a gap between the free displacer (37) and the cylinder (31) is sealed to maintain a high pressure in the working space (36). The second clearance seal (53) is fitted.

A spiral spring mounting groove (41) is formed at the base end (42) of the free displacer (37). on the other hand,
Working space (36) for flange (33) protruding into cylinder (31)
A spiral spring mounting groove (43) is also formed on the side. One end of the coil spring (44) is attached to the spring attachment groove (41), and the other end is attached to the spring attachment groove (43), so that the free displacer (37) reciprocates by the coil spring (44). It is freely elastically supported.

A gas hole (45) communicating with the working space (36) is formed through the flange (33). A connecting pipe (16) extending from the compressor (1) is inserted into the gas hole (45).
(16) is airtightly joined to the flange (33). Therefore,
The working space (36) communicates with the compression space (13) of the compressor (1) via the connection pipe (16). Then, the free displacer (37) of the expander (2) reciprocates in the cylinder (31) in response to the gas pressure from the compressor (1), thereby forming the expansion space (3).
In 5), the working fluid expands, and the heat station (32) is cooled. That is, cryogenic cold is generated in the heat station (32).

A cooling fin (46) for cooling gas in the working space (36) is provided around the working space (36) in the cylinder (31).

-Configuration of the clearance seal-Next, the clearance seal (1
2), (52) and (53) will be described. As described above, the clearance seals (12), (52), and (53) are each a compressor (1).
Are provided on the outer peripheral surface of the piston (11), the outer peripheral surface of the distal end (48) of the free displacer (37) of the expander (2), and the outer peripheral surface of the proximal end (42). Since their configurations are the same, only the configuration of the clearance seal (12) provided on the piston (11) of the compressor (1) will be described here.

FIG. 3 shows one piston (11) of the compressor (1).
FIG. 7 is a partial cross-sectional view of the vicinity of a cylinder (6). Note that FIG.
In order to make it easier to understand, the clearance seal
The length in the thickness direction of (12) is exaggerated. On both sides of the seal surface of the clearance seal (12) in the axial direction (X direction shown in FIG. 3) of the piston (11), the cross section is formed in a straight line. Between the flat portions (55), (55), a concave portion (57) having a symmetrical cubic curve in cross section is formed. On the other hand, the inner surface of the clearance seal (12) fixed to the piston (11) is formed as a smooth circumferential surface (58).

The clearance seal (12) mainly performs the sealing action at the smallest portion of the clearance. for that reason,
In the state before the wear of the clearance seal (12), that is, in the initial state, the concave portion (57) hardly performs a sealing action, and the sealing action is mainly performed in the flat portion (55).

The thickness t1 and the axial length L1 of the flat portion (55)
In the state where the clearance length s1 and the seal length 2 × L1 are not worn before the clearance seal (12) is worn, the piston
The length is set so that the resistance of the reciprocating movement of (11) is not too large and a sufficient sealing performance is exhibited. In other words, the flat portion (55) is configured so that only the flat portion (55) exhibits sufficient sealing performance in the initial state. Specifically, in the present embodiment, the clearance length s1 is set to about 10 μm. Here, the seal length refers to the length of a portion of the sealing surface of the clearance seal (12) that actually contributes to the sealing action.

On the other hand, the concave portion (57) is provided with the clearance seal (1).
It is formed in such a shape that the leakage amount of the working fluid is always constant irrespective of the abrasion of 2). Specifically, the specification is set based on the following theory.

When the working fluid leaks from the clearance (gap) between the piston (11) and the cylinder (6), it is considered that the working fluid flows through the clearance in a laminar state. Therefore, the leakage coefficient is α, the outer diameter of the piston (11) is d,
Assuming that the clearance is Δh, the differential pressure of the seal portion is ΔP, and the seal length is L, the leakage amount W is W = α · d · Δh ³ · Δ
Estimated as P / L. Therefore, A = (Δh ³ / L)
Is constant, the leakage amount W of the working fluid becomes constant. Therefore, the concave portion (57) has a cubic curve shape such that when the flat portion (55) wears out and the clearance s1 increases, the seal length L1 of the flat portion (55) increases and A becomes constant. Is formed.

In this embodiment, the depth of the concave portion (57) is about 10 μm, which is almost equal to the clearance length s1.

The clearance seal (12) of this embodiment is
It is formed of a resin obtained by adding carbon as a filler to a base material made of ethylene tetrafluoride, that is, PTFE (polytetrafluoroethylene). The material of the clearance seal (12) is not limited to the resin, for example, one or two or more of polyimide, polyamide imide or polyacetal as a base material, carbon as a filler, carbon fiber, It may be a resin using one or more of bronze and molybdenum disulfide.

-Operation of Stirling refrigerator- Next, the operation of the Stirling refrigerator will be described.

At the start of the operation, an alternating current is synchronously supplied from a drive power supply (not shown) to the drive coil (22) of the linear motor (17). With this energization, the drive coil (22)
The movable part (19) of the linear motor (17) and the piston (11) reciprocate in an opposite direction so that they come into contact with and separate from each other from their neutral positions as a unit by the action between the magnetic fields of the drive magnet (18) and the drive magnet (18). Make the move. Then, the volume of the compression space (13) increases or decreases due to the contact and separation of the pistons (11), and a pressure wave of a predetermined cycle is generated in the compression space (13). Since the compression space (13) communicates with the working space (36) of the expander (2) through the connecting pipe (16), the free displacer (37) reciprocates at the predetermined cycle in response to the pressure wave. . As a result, the working fluid expands in the expansion space (35), and cold occurs in the expansion space (35). Thus, the reciprocating movement of the free displacer (37)
The heat station (32) is gradually cooled to a very low temperature.

-Effects of this Embodiment- As described above, according to this embodiment, in the initial state, the clearance can be reduced while the seal length can be shortened. While maintaining
The resistance of reciprocation of the piston (11) and the free displacer (37) can be reduced. Even if the clearance seals (12), (52), and (53) are worn, the seal length is increased in accordance with the increase in the clearance, so that the leakage amount of the working fluid can be kept constant. Therefore, a decrease in sealing performance due to wear can be suppressed, and the initial sealing performance can be maintained for a long period of time. Therefore, the refrigerating capacity of the Stirling refrigerator can be maintained for a long time.

In FIG. 13, the performance of the clearance seals (12), (52), (53) of the present embodiment is shown by the solid line curve shown in FIG. It can be seen that a high level of initial performance is maintained over a long period of time as compared to the conventional clearance seal indicated by the dashed line and the dashed line.

-Modifications- The clearance seal according to the present invention is not limited to the above-described clearance seal (12), and various modifications are conceivable.

<Modification 1> For example, as shown in FIG.
A configuration in which the concave portion (57) of the clearance seal (12) is replaced with a V-shaped portion (60) having a V-shaped cut surface may be adopted. The inclination and length of the cut surface are determined by the clearance seal.
With the wear of (12), the flat portion (55) increases to increase the seal length, and an increase in leakage due to an increase in clearance is set to be suppressed by an increase in seal length.

Therefore, even in such a mode, it is possible to make the amount of leakage of the working fluid substantially constant. Further, since the V-shaped portion (60) is formed by a cut surface having a linear cross section, it can be easily manufactured. Therefore, the manufacture of the clearance seal (12) becomes easy.

<Modification 2> As shown in FIG. 5, the clearance seal (12) may be composed of a flat portion (55) and an inclined portion (61). The inclination angle of the inclined portion (61) is set so that the area of the flat portion (55) increases due to wear of the clearance seal (12), and an increase in leakage due to an increase in the clearance is suppressed by an increase in the seal length. ing.

Therefore, even in such a mode, the leakage amount of the working fluid can be made substantially constant irrespective of the wear of the clearance seal (12), similarly to the first modification. Therefore, the initial sealing performance can be maintained for a long time. The clearance seal (12) is flat (5
Since it has a simple shape consisting of 5) and the inclined portion (61), it can be easily manufactured.

<Modification 3> Further, as shown in FIG. 6, the concave portion (57) of the clearance seal (12) may be replaced with a concave portion (57a) having a U-shaped cross section. That is, a concave portion (57a) having a rectangular cross section is provided at the central portion in the axial direction.
a) Clearance seal with flats (55) on both sides of a)
(12). The length and depth of the recess (57a) depend on the amount of fluid leakage in the initial state and the clearance seal (1
2) is set so that the amount of leakage when the flat portion (55) and the bottom of the concave portion (57a) become flush with each other and the level of leakage becomes equal. The depth of the concave portion (57a) is set so that the clearance between the bottom surface of the concave portion (57a) and the inner wall surface of the cylinder (6) is equal to or less than the critical clearance at which the amount of fluid leakage is extremely large. ing.

For example, if the critical clearance is about 20 μm and the initial clearance is about 10 μm,
The depth of the concave portion (57a) is preferably about 10 μm.

Further, the size of the concave portion (57a) may be set based on the above theory regarding the fluid leakage characteristics. That is, since the leakage amount of the fluid in the laminar flow state is proportional to the cube of the clearance and inversely proportional to the seal length, the initial clearance is h1, the length of the seal surface is L, and the depth of the concave portion (57a). the h2, the length of the recess (57a) when the L1, h1 ³ /
It may be formed so as to satisfy the relationship of (L−L1) ≒ (h1 + h2) ³ / L.

In the case of this embodiment, the seal length does not continuously increase with the wear of the clearance seal (12) as in the first and second modifications, but when the clearance reaches the critical clearance. Since the seal length increases stepwise, a remarkable decrease in sealing performance is prevented. Also, by cutting the central part in the axial direction of the outer peripheral surface of the cylindrical clearance seal, the flat part (55) and the concave part (5
7a) can be easily formed. Therefore, the clearance seal (12) of this embodiment can be manufactured very easily.

<Modification 4> As shown in FIG. 7, a flat portion constituting the main seal surface is provided at the tip end of the clearance seal (12).
(55), and a groove (57
c) may be formed. The cross-sectional shape of the groove (57c) is formed flat similarly to the flat part (55). Flat part (55)
Is opposed to the inner wall surface of the cylinder (6) with an initial clearance, and the groove (57c) is opposed to the inner wall surface of the cylinder (6) with a clearance larger than the initial clearance. The clearance seal (12) of this embodiment can also be manufactured very easily.

<Modification 5> As shown in FIG. 8, a clearance seal (12) formed so that a plurality of flat portions (55) and a plurality of recesses (57b) are alternately repeated. Is also good. Even in such a form, the same effects as those of the third and fourth modifications can be obtained. In addition, this clearance seal (1
In 2), since the flat portion (55) is provided over a wide range in the axial direction, the sealing action can be stably performed.
In addition, the structure of the clearance seal (12) becomes solid.

In this modification, the specification of the concave portion (57b) as a rectangular groove may, of course, be set based on the above theory regarding the fluid leakage characteristics.

[0089]

Second Embodiment -Configuration of Turbo Refrigerator- FIG. 9 shows a turbo compressor (70) provided with a seal mechanism according to the present embodiment. Inside the closed cylindrical casing (71), a disk-shaped upper partition wall (72) is provided at a position having a predetermined size below the upper end, and at a position having a predetermined size above the lower end. A disk-shaped lower partition (73) is provided.
The upper partition (72) partitions the internal space of the casing (71) into an upper first impeller chamber (74) and a lower motor chamber (75). On the other hand, the lower partition (73) partitions the internal space of the casing (71) into a lower second impeller chamber (76) and an upper motor chamber (75).

The first impeller chamber (74) and the second impeller chamber (7)
The first impeller (7) formed at the center of the casing (71) in the axial cross section and connected to both sides of the drive shaft (77).
8) and a storage chamber for storing the second impeller (79). The shapes of the first impeller (78) and the second impeller (79) are substantially frustoconical with the inner diameter gradually increasing toward the center of the casing (71). The first impeller (78) is the first
The second impeller (79) is rotatably housed in the second impeller chamber (76) inside the impeller chamber (74). The first impeller (78) and the second impeller (79) have a plurality of substantially triangular blades (80), (80),... Provided radially around a vertical axis to generate outward radial flow. It constitutes a radial type rotating body.

A suction pipe (81) is connected to the center of the upper end surface of the casing (71). Between the suction pipe (81) and the first impeller chamber (74), the refrigerant flowing through the suction pipe (81) is supplied to the first impeller chamber (74).
A suction passage (82) leading from the upper side of the first impeller (78) to the first impeller chamber (74) is formed along the axial direction of the impeller (78).

A first spiral chamber (83) and a second spiral chamber (84) are formed around the outer periphery of the first impeller chamber (74) and the outer periphery of the second impeller chamber (76), respectively. These spiral chambers (83),
(84) is connected to the impeller chamber (7) through the diffusers (85) and (86).
4), (76).

First spiral chamber on the side surface of the casing (71)
At a position corresponding to (83), one end of a first communication pipe (87) for guiding the refrigerant pressurized by the first impeller (78) and the diffuser (85) to the motor chamber (75) is connected. 1st communication pipe
The other end of (87) is the motor chamber on the side of the casing (71).
It is connected to the upper part of (75).

A second communication pipe (88) for guiding the refrigerant inside the motor chamber (75) to the suction side of the second impeller chamber (76) is connected to a side surface of the casing (71). One end of the second communication pipe (88) is connected to the lower part of the motor chamber (75) on the side surface of the casing (71), and the other end is connected to the center of the lower end surface of the casing (71). Between the second communication pipe (88) and the second impeller chamber (76), the refrigerant in the motor chamber (75) is transferred along the axial direction of the second impeller (79) to the lower side of the second impeller (79). A suction passage (89) is formed to lead from the second impeller chamber (76) to the second impeller chamber (76).

The second spiral chamber on the side surface of the casing (71)
A discharge pipe (90) extending in the horizontal direction toward the outside of the casing (71) is connected to a position corresponding to (84). A second spiral chamber (84) is provided between the second spiral chamber (84) and the discharge pipe (90).
A discharge passage (91) for guiding the refrigerant to the discharge pipe (90) is formed.

The motor chamber (75) houses a motor (92) for rotating and driving the first impeller (78) and the second impeller (79). The motor (92) has a stator (93) fixed to the inner wall surface of the motor chamber (75), and a rotor (9) housed inside the stator (93) and arranged concentrically with the impellers (78, 79).
4). The rotor (94) is fixed at its center to a drive shaft (77) extending in the vertical direction.

The drive shaft (77) has a large diameter portion (101) and a large diameter portion (101).
And small-diameter portions (102) provided on both sides. Upper and lower sides of the large-diameter portion (101) of the drive shaft (77) are rotatably supported via a first bearing plate (95) and a second bearing plate (96). Specifically, the upper end of the drive shaft (77) is inserted into a through hole (97) formed in the center of the first bearing plate (95), and the lower end of the drive shaft (77) is connected to the second bearing plate. It is inserted through a through hole (98) formed at the center of (96).

On the outer peripheral surface of both upper and lower ends of the large diameter portion (101),
Herringbone grooves (99,99,
…) Is formed. This herringbone groove (99,99,…)
The outer peripheral surface of the large diameter portion (101) of the drive shaft (77) and the through holes (97, 98)
Is formed so as to generate a gas film by a gas pressure in a gap between the inner peripheral surface and the inner peripheral surface. The gas film forms a gas bearing that supports the drive shaft (77) in a non-contact state.

A thrust bearing plate (103) is provided between the second bearing plate (96) and the lower partition wall (73).
In the center of the thrust bearing plate (103), a through hole having substantially the same shape as the small diameter portion (102) of the drive shaft (77) is formed, and the inner surface of this through hole and the outer peripheral surface of the small diameter portion (102) are connected. The drive shaft (7
7) and the thrust bearing plate (103) are integrally fixed. The lower surface of the thrust bearing plate (103) faces the upper surface of the lower partition wall (73), and the upper surface of the thrust bearing plate (103) faces the lower surface of the second bearing plate (96). A substantially spiral spiral groove (not shown) constituting a thrust side pressure raising mechanism is formed on both upper and lower surfaces of the thrust bearing plate (103). Then, by the action of the spiral groove, between the thrust bearing plate (103) and the lower partition (73), and between the thrust bearing plate (103) and the second bearing plate (96).
A dynamic pressure gas bearing that forms upward and downward thrust bearings is formed between the two, and the drive shaft (77) is supported in the thrust direction.

Clearance seals (104) and (104) are fixed to the outer peripheral surfaces of both small diameter portions (102) and (102) of the drive shaft (77), respectively. Since the configuration of each clearance seal (104) is the same, here, the small diameter portion (10
Only the configuration of the clearance seal (104) provided in 2) will be described.

-Sealing mechanism of the present embodiment-As shown in FIG. 10, the clearance seal of the present embodiment
As in the first embodiment, the cross-sectional shape of (104) is such that both sides in the axial direction are flat, and a cubic curved concave portion (106) is formed between the flat portions (105) and (105). Have been. Flat part
The thickness and the length in the axial direction of (105) are set to a thickness and a length such that the rotation resistance of the drive shaft (77) in the initial state is not too large and sufficient sealing performance is exhibited. Like the first embodiment, the concave portion (106) is also formed in a shape such that the amount of refrigerant leakage is always constant regardless of the wear of the clearance seal (104). Specifically, the concave portion (106) is described in the first embodiment. Based on theory, the cross-sectional shape is formed into a curved surface having an edge of a predetermined cubic curve. The material of the clearance seal (104) is the same as that of the first embodiment.

-Operation of Turbo Compressor (70)-First, during the compression operation, the motor (92) is driven and the drive shaft (7
7) rotates at high speed. Then, according to the rotation of the drive shaft (77), the first impeller (78) and the second impeller (79) rotate in the first impeller chamber (74) and the second impeller chamber (76), respectively.

The first impeller in the first impeller chamber (74)
By the rotation of (78), the refrigerant is sucked into the first impeller chamber (74) through the suction pipe (81) and the suction passage (82). The refrigerant guided to the first impeller (78) along the axial direction of the first impeller (78) flows outward in the radial direction along the blades (80), (80), ... of the first impeller (78). And is discharged from the outer peripheral end of the first impeller (78). At this time, the refrigerant obtains dynamic pressure and static pressure by centrifugal force given from the first impeller (78), and passes through the diffuser (85). The refrigerant decelerates in the diffuser (85),
The dynamic pressure is converted to static pressure and the dynamic pressure is recovered. as a result,
The refrigerant is pressurized and discharged to the first spiral chamber (83). afterwards,
The refrigerant flows out of the first spiral chamber (83), flows through the first communication pipe (87), and flows into the motor chamber (75).

The refrigerant in the motor chamber (75) is supplied to the second impeller chamber (7).
The rotation of the second impeller (79) in 6) causes the second communication pipe to rotate.
It is sucked from (88) and guided to the second impeller (79). Second
The refrigerant guided to the second impeller (79) along the axial direction of the impeller (79) becomes an outward radial flow along the blades (80), (80), ... of the second impeller (79), It is discharged from the outer peripheral end of the second impeller (79). Thereafter, in the same manner as in the compression operation in the first impeller chamber (74), the pressure of the refrigerant is increased and the pressure in the second spiral chamber is increased.
(84) and is discharged as a high-pressure gas from the discharge pipe (90).

-Effects of this Embodiment- Also in this embodiment, by reducing the clearance and shortening the seal length in the initial state, the drive shaft (77) can maintain sufficient sealing performance. , The rotational resistance can be reduced. On the other hand, even if the clearance seal (104) wears, the length of the seal increases with an increase in the clearance, so that the amount of refrigerant leakage is always constant. Therefore, the initial sealing performance of the clearance seal (104) can be maintained for a long time.

In particular, a non-contact seal made of a metal material has been often used for a high-speed turbine, a turbo, or the like. However, if the sealing performance is to be improved, it is necessary to increase the precision of the dimensions and the cost is increased. I was In addition, if there is a contact portion, there is a possibility of burning. However, in the present embodiment, the use of the clearance seal (104) can maintain the same sealing performance as in the initial stage even if it is initially contacted and worn, so that it is possible to allow some contact. is there. Therefore, it is not necessary to make the dimensional accuracy higher than in the past, and the cost can be reduced.

-Modifications- The clearance seal according to the present embodiment is not limited to the clearance seal (104), and various modifications are conceivable. For example, Modifications 1-4 of the first embodiment
As in the case of the clearance seal (104), the concave portion (106) of the clearance seal (104) is replaced with a V-shaped concave portion.
May be configured with flat portions and inclined portions, a configuration in which the concave portion (106) of the clearance seal (104) is replaced with a concave portion having a rectangular cross section, a configuration in which a plurality of flat portions and a plurality of concave portions are alternately repeated, or the like. Good.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a compressor.

FIG. 2 is a longitudinal sectional view of the expander.

FIG. 3 is a vertical sectional view of a seal mechanism.

FIG. 4 is a longitudinal sectional view of a modified example of the seal mechanism.

FIG. 5 is a longitudinal sectional view of another modification of the seal mechanism.

FIG. 6 is a longitudinal sectional view of another modification of the seal mechanism.

FIG. 7 is a longitudinal sectional view of another modification of the seal mechanism.

FIG. 8 is a longitudinal sectional view of another modification of the seal mechanism.

FIG. 9 is a longitudinal sectional view of the turbo compressor.

FIG. 10 is a longitudinal sectional view of a seal mechanism.

FIG. 11 is a longitudinal sectional view of an expander provided with a conventional sealing mechanism.

FIG. 12 is a longitudinal sectional view of an expander provided with a conventional sealing mechanism.

FIG. 13 is a performance comparison diagram of the seal mechanism.

[Explanation of symbols]

 (1) Compressor (2) Expander (6) Cylinder (11) Piston (12) Clearance seal (13) Compression space (18) Drive magnet (21) Bobbin (22) Drive coil (29) Coil spring ( 31) Cylinder (37) Free displacer (52) First clearance seal (53) Second clearance seal (55) Flat (57) Recess

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F25B 9/14 510 F04D 29/10 F25B 1/053 F25B 31/02

Claims (9)

(57) [Claims] A first member having a first facing surface;
A second member (6,72) having a second opposing surface opposing the first opposing surface with a gap therebetween; and a seal opposing the second opposing surface at a predetermined interval (s1). Surface of the first member (11,102) so as to have a surface.
A clearance seal (12, 104) provided on the opposing surface, wherein the first member (11, 102) and the second member (6, 72) perform relative motion, while the first opposing surface and the second opposing surface In a seal mechanism for sealing between the surfaces, the sealing surface of the clearance seal (12, 104) includes:
A main sealing surface (55, 105) facing the second opposing surface with a predetermined initial clearance; and a sub-sealing surface (57, 60, 106) opposing the second opposing surface with a clearance larger than the initial clearance. ) Is formed. 2. The sealing mechanism according to claim 1, wherein the sealing surface of the clearance seal (12, 104) has a groove (57, 6).
(0,106) is formed, and the main sealing surface of the clearance seal (12,104) is constituted by the non-groove portion (55,105), while the auxiliary sealing surface of the clearance seal (12,104) is constituted by the groove (57,60,106). A sealing mechanism characterized by being performed. 3. The sealing mechanism according to claim 2, wherein the grooves (57, 60, 10) in the sealing surface of the clearance seal (12, 104) are provided.
6) The sealing mechanism, wherein the amount of leakage of the fluid is formed so as to be substantially the same before the seal surface is worn and after the predetermined amount of wear. 4. The sealing mechanism according to claim 1, wherein a sectional shape of a sealing surface of the clearance seal (12, 104) is:
A flat portion (55) parallel to the second facing surface of the second member (6, 72); and an inclined portion (61) inclined from the flat portion (55) to the first facing surface side of the first member (11, 102). The main seal surface of the clearance seal (12, 104) is composed of the flat portion (55), while the auxiliary seal surface of the clearance seal (12, 104) is composed of the inclined portion (61). A sealing mechanism. 5. The seal mechanism according to claim 4, wherein the inclined surface of the sealing surface of the clearance seal is formed.
The seal mechanism is characterized in that the amount of fluid leakage is substantially the same before the seal surface is worn and after a predetermined amount of wear. 6. The seal mechanism according to claim 1, wherein the clearance seal (12,104) is made of one or more of polytetrafluoroethylene, polyimide, polyamideimide, and polyacetal. A sealing mechanism comprising a base material and a resin material containing one or more of carbon, carbon fiber, bronze, and molybdenum disulfide as a filler. 7. A compressor (1) that compresses a working gas by reciprocating a piston (11) in a predetermined cycle in a cylinder (6) and generates a gas pressure in a predetermined cycle in the cylinder (6). Is connected to the cylinder (6) of the compressor (1) so that the gas pressure is supplied, and the gas pressure causes the displacer (37) to reciprocate in the cylinder (31), thereby expanding the expansion space (35). )
In the refrigerator provided with an expander (2) for generating cold in the heat station (32) by expanding the working gas in the above, the piston (11) and the cylinder (6) of the compressor (1)
As a first member and a second member, respectively.
A refrigerator provided with the seal mechanism according to any one of the above. 8. A compressor (1) for compressing a working gas by reciprocating a piston (11) in a predetermined cycle in a cylinder (6) and generating a gas pressure in a predetermined cycle in the cylinder (6). Is connected to the cylinder (6) of the compressor (1) so that the gas pressure is supplied, and the gas pressure causes the displacer (37) to reciprocate in the cylinder (31), thereby expanding the expansion space (35). )
And a expander (2) for generating cold in the heat station (32) by expanding the working gas in the refrigerator, wherein the displacer (37) and the cylinder (31) of the expander (2)
As a first member and a second member, respectively.
A refrigerator provided with the seal mechanism according to any one of the above. 9. The casing (71) is partitioned into a motor chamber (75) and an impeller chamber (74, 76) by partition walls (72, 73), and the impeller (78, 79) connected to the drive shaft (77). ) Rotates in the impeller chamber (74, 76) to compress the refrigerant, wherein the drive shaft (77) and the partition (72, 73) are respectively a first member and a second member. A turbo compressor provided with the seal mechanism according to any one of Items 1 to 6.