JPH01310270A - Refrigerating machine - Google Patents

Abstract

PURPOSE:To move a piston member reciprocally without any contact and eliminate the abrasion of a seal for the piston member by a method wherein the seal for the piston member is constituted of a clearance seal utilizing a narrow clearance between the piston member and a housing constituting the wall of a cold finger section while a static pressure bearing is formed in the clearance sealing section. CONSTITUTION:A seal 17 for a piston member, which separates an operating space 11 from a gas spring space 16, is constituted of a clearance seal utilizing a narrow clearance between the piston member 15 and a housing 9 constituting the wall of a cold finger section 2 while a surface choking type static pressure bearing 20 is formed in the clearance seal section. The flow of operating gas from the operating space into the gas spring space 16 is generated in the static pressure bearing 20 provided on the clearance seal of the seal 17 for the piston member whereby the piston member 15 is permitted to make reciprocating operation without contacting with the wall of the opposing housing 9, the abrasion of the seal 17 for the piston member is eliminated and a refrigerating machine having a long life may be obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a refrigerator in which a moving body is driven to reciprocate by a pressure difference between its ends, such as a free piston type Stirling refrigerator used for cooling an infrared element.

[Conventional technology]

(I) to (IV) in FIG. 8(a) are, for example,
This figure shows the structure and operation of a conventional refrigerator disclosed in Japanese Patent No. 73873, and this refrigerator includes a reciprocating compressor 1 and a cold finger section 2. The compressor 1 is composed of a piston 3 and a cylinder 4 that houses the piston 3. A working gas such as helium is pressurized inside the cylinder 4.
It is enclosed. A piston seal 5 is provided between the piston 3 and the cylinder 4, which separates a second compression space 6 and a buffer space 7, which form part of the working space, as well as a motor and a drive mechanism housed within the cylinder (Fig. When the piston 3 is driven to reciprocate within the cylinder 4 by a cylinder (not shown), one surface thereof causes a sinusoidal pressure fluctuation within the second compression space 6. The sinusoidal pressure fluctuations within the second compression space 6 are transmitted into the cold finger section 2 through the supply vibrator 8. Inside the housing 9 of the cold finger section 2, a cylindrical moving body 10 is reciprocated to change the volumes of a first compression space 11 and an expansion space 12 within the cold finger section 2. The moving body 10 houses a regenerative heat exchanger 13 and is also provided with a moving body seal 14 so that helium gas flows between the first compression space 11 and the expansion space 12 through the heat exchanger 13. It is configured. Furthermore, the mobile body 1
0 includes a piston member 15 integral therewith, and a gas spring space 16 into which the piston member 15 is inserted is separated from the first compression space 11 by a piston member seal 17 provided around the gas spring space 16. The refrigerator described above is understood to include three separate gas spaces. That is, the gas working space is composed of the second compression space 6, the space inside the supply pipe 8, the first compression space 11, the expansion space 12, and the space inside the heat exchanger 13. Another gas space is formed by the buffer space 7 and the gas spring space @16, and each of the above spaces is
They are separated by a piston seal 5 and a piston member seal 17, respectively. Next, the operation of the refrigerator described above will be explained using FIG. 8(b). At the time of cycle (I) in FIG. 8(a), the lower end of the moving body 10 is connected to the cold finger portion 2.
The compression movement of the compressor 1 increases the pressure in the working space from the lowest pressure to the highest pressure. The pressure within the spring space 16 is at a level between the lowest and highest pressure levels within the working space, and thus the increasing pressure within the working space will at some point cause the moving body seal 14 and the piston member to A sufficient pressure difference is generated against the piston member 15 to overcome the frictional resistance of the seal 17. Therefore, piston member 1
5 and the moving body 10 rapidly rise to the position shown in (II) of FIG. 8(a). Due to the movement of the moving body 10, the high-pressure gas at approximately ambient temperature in the first compression space 11 passes through the heat exchanger 13, is precooled, and is then introduced into the expansion space 12. Thus, the sinusoidal movement of the piston 3 by the drive mechanism (not shown) begins to expand the volume of the working space as shown in (IN) in FIG.
The high pressure helium gas within 2 is further cooled. The cooling effect of this refrigerator is mainly generated during this process. Next, at a certain point in this expansion movement of the piston 3, the pressure in the working space drops below the pressure in the gas spring space 16, and the pressure difference overcomes the am resistance of the moving body seal 14 and the piston member seal 17. Once the pressure difference is sufficient to overcome, the moving body 10 and the piston member 1
5 is driven downward toward the position (IV> in FIG. 8(a). The position (IV) in FIG. 8(a) is before reaching (I) in FIG. 8(a). It is also the position of
At this time, the cooled gas in the expansion space 12 is transferred to the heat exchanger 1
3, it emits cold heat to the heat exchanger 13 and becomes a gas at approximately ambient temperature, which then enters the first compression space 11.
Return to As described above, as shown in FIG. 8(b), when the movable body 10 moves while maintaining a certain appropriate phase difference with respect to the pressure change in the working space in each process of the cycle, the The activated working gas constitutes a thermodynamic cycle known as the "inverted Stirling cycle" and is capable of generating cold heat primarily within the expansion space 12. For details on the above-mentioned ``reverse Stirling cycle'' and its principle of cold generation, please refer to the document ``Cryocoole''.
r s ”. (G. Walker, Plenum Press. New York, 1983).

[Problem to be solved by the invention]

Conventional refrigerators are constructed as described above, so if the sealing ability of the piston member seal becomes directional due to wear during operation, the average pressure in the gas spring space and the average pressure in the working space will change. A pressure difference occurs between them due to this directionality, and furthermore, this pressure difference is as shown in Fig. 8(b).
As shown in Figure 2, the timing of the reciprocating movement of the moving body is changed from the initially set optimum value, resulting in a change in the capacity of the refrigerator. In addition, the reduction in the capacity of the seal for the piston member increases the leakage of gas from the working space to the gas spring space, which in turn reduces the amplitude of the pressure change in the working space, resulting in a reduction in the capacity of the gas spring. urge In conventional refrigerators configured in this way, changes in the sealing ability of the piston member seal due to wear etc. cause a significant decrease in the refrigerating function, so it is difficult to create a refrigerator with sufficient durability and reliability. There was a problem that I couldn't get it. This invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a refrigerator having excellent durability and reliability and having a seal for a piston member with little wear.

[Means to solve the problem]

Cold for this invention? ! am connects the buffer space and the gas spring space by a first connection circuit, and connects the buffer space and the working space by a second connection circuit in which a check valve is provided in the middle; The seal for the piston member is constituted by a gap seal that utilizes a narrow gap between the piston member and the housing forming the wall of the cold finger portion, and a hydrostatic bearing is formed in the gap seal portion.

[For production]

In the refrigerator according to the present invention, working gas is pumped from the bath sofa space to the working space by a check valve provided in the middle of a second connection circuit that connects the buffer space and the working space, The pressure in the working space is always maintained higher than the pressure in the buffer space and the gas spring space communicated with the buffer space by a first connection circuit. In this way, in the static pressure bearing provided on the clearance seal of the piston member seal, the piston member reciprocates without contact due to the flow of working gas from the working space to the gas spring space, so that the screw T/n member As a result, a long-life refrigerator can be obtained.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 18 is a second connection circuit, which connects the buffer space 7 and the second compression space 6 forming a part of the working space, and a check valve 19 is provided in the middle of the second connection circuit. , only the flow of working gas from the buffer space 7 to the working space 6 is allowed. On the other hand, the piston member seal 17 that separates the operating space from the gas spring space 16 is constituted by a gap seal that utilizes a narrow gap between the piston member 15 and the housing 9 forming the wall of the cold finger section 2. ,
A surface drawing type static pressure bearing 20 is formed in the gap seal portion. In addition, 21 is a gas spring space 16
This is a first connection circuit that communicates between the buffer space 7 and the gas spring space 1 from the operating space through the static pressure bearing 20.
This serves as a return circuit for the working gas that has flowed out to 6. Furthermore, a coil spring 22 is provided in the gas spring space 16 as a means for correcting the center position of the reciprocating movement of the moving body 10.
is provided and coupled to the piston member 15 and the cold finger portion 2. In addition, in the figure, the parts with the same symbols as in FIG. 8(a) are as shown in FIG. 8(a).
The same parts as in a) are shown, and the explanation here will be omitted. Next, the operation of this embodiment will be explained using FIG. 2. Similar to the conventional example, the sinusoidal vertical movement of the piston 3 by a motor and drive mechanism (not shown) moves the piston 3 into the second compression space 6.
Then, a sinusoidal pressure change is caused in the working gas in the working space consisting of the space inside the supply vibe 8, the first compression space 11 and the expansion space 12, and the space inside the heat exchanger 13. However, in this embodiment, a check valve 19 is provided in the middle of a second connection circuit 18 that connects the buffer space 7 and the working space, and the working gas is pumped from the buffer space 7 to the working space. As shown in FIG. 2(a), the pressure in the working space is as follows.
the buffer space 7 and the gas spring space 16 communicated with the buffer space 7 by a first connection circuit 21;
The pressure will almost always be higher than that of . At this time, the coil spring 22 provided in the gas spring space 16 is adjusted to match the average pressure in the gas spring space 16 and the average pressure in the working space so that the center of reciprocation of the movable body 10 is at the set position. Since the force corresponding to the pressure difference is compensated for, a sinusoidal driving force shown in FIG. Since the system is configured, the moving body 10
Due to this driving force, LIII! has a certain phase delay with this driving force as shown in FIG. ! Do exercise. Furthermore, at the time of B, a flow of working gas is generated from the working space to the gas spring space 16 in the static pressure bearing 20 provided on the gap seal of the screw member seal 17, and the piston member 15 is moved relative to the gas spring space 16. It becomes possible to reciprocate without contacting the wall of the housing 9. In this way, when the movable body 10 performs reciprocating motion while maintaining a certain phase difference with respect to the pressure change in the working space, the working gas in the working space moves in the 'reverse Stirling cycle' as described in the explanation of the conventional example. ” and generates cold heat in the expansion space 12. As described above, in the refrigerator according to this embodiment, the piston member seal 17 is composed of a gap seal, and furthermore, the seal 17 provided on this gap seal is Since the piston member 15 reciprocates without contact by the hydrostatic bearing 20, wear of the piston member seal 17 is eliminated, and a long-life refrigerator can be obtained.For reference, FIG. The operating principle of the surface-drawn type hydrostatic bearing will be briefly explained below.The surface-drawn type hydrostatic bearing used in this embodiment has a piston member 15 and a A step is provided on the piston member 15 so that the gap between the walls of the cold finger portion 2 is larger on the working space side than on the gas spring space 16 side, and furthermore, the pressure P on the working space side is The pressure P2 on the side of the space 16 is always higher than the pressure P2.Here, as shown in FIG. 3(a), the piston member 15
When the center of the cold finger portion 2 coincides with the center of the wall of the cold finger portion 2, the lateral forces acting on both sides of the piston member are symmetrical and have the same magnitude distribution as shown by the arrows. Further, as shown in FIG. 3(b), when the piston member 15 is centered with respect to the cold finger portion 2, the pressure on the side where the gap is smaller due to eccentricity is higher than the pressure on the opposite side. As a result, a reaction force is generated that pushes back the piston member 15 and attempts to align the centers of the piston member 15 and the cold finger portion 2. This action means that the lateral load of the piston member 15 can be supported while the piston member 15 remains floating relative to the cold finger portion 2. As a result, the piston member 15
can move back and forth without contact. In the above embodiment, the cold finger section 2 and the compressor 1 are separated from each other via the supply pipe 8. - Although the case of a type refrigerator has been described, it is also possible to use an integrated type refrigerator in which the cold finger section 2 and the compressor 1 are mechanically strongly coupled, as in another embodiment of the present invention shown in FIG. However, the same effect as in the above embodiment can be obtained. Further, in the above embodiment, only the piston member seal 17 is used as a clearance seal, but the movable body seal 14 may also be used as a clearance seal at the same time as in another embodiment of the present invention shown in FIG. , in this case, moving object seal 1
Since the wear of 4 is also extremely reduced, the life of the - layer is extended. Furthermore, as in another embodiment of the present invention shown in FIG. 6, the piston seal 5 is also formed as a clearance seal with a hydrostatic bearing, thereby making it possible to further extend the life of the piston. Further, as in another embodiment of the present invention shown in FIG. 7, an adsorption chamber 23 for removing impurities in the working gas and abrasion particles may be provided in the second connection circuit 18. By doing so, accidental failure of the refrigerator due to the entrapment of wear debris is prevented, and a highly reliable refrigerator can be obtained.

【Effect of the invention】

As described above, according to the present invention, the piston member seal is constituted by a clearance seal that utilizes a narrow clearance between the piston member and the housing forming the wall of the cold finger portion, and the clearance seal By forming a hydrostatic bearing in the part, the piston member can reciprocate without contact, and there is no wear on the seal for the piston member, so it is possible to obtain a refrigerator with improved durability and reliability. It has a calming effect.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing a refrigerator according to an embodiment of the invention, FIG. 2 is an explanatory diagram showing the operation of the refrigerator according to an embodiment of the invention, and FIG. 3 is an embodiment of the invention. An explanatory diagram showing the operation of the surface drawing type hydrostatic bearing used in Figure 4~
FIG. 7 is a cross-sectional side view of a refrigerator showing another embodiment of the present invention, and FIG. 8 is a cross-sectional side view of a conventional refrigerator. 1 Compressor, 2 Cold finger section, 3 Piston, 4 Cylinder, 5 Piston seal, 6 Second compression space, 7 Buffer space, 8 Supply pipe, 9 Housing, 10 Moving body, 11 First compression space, 12 Expansion space , 13 #I exchanger, 14 Seal for mobile object, 1
5-Biston member, 16 Gas spring space, 17
Seal for piston member, 18 ・Second connection circuit, 19
Check valve, 20 Static pressure bearing, 21...first connection circuit, 2
2 coil spring, 23 suction chamber. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1 Figure 3 (b) Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure I) (■) Figure (a)

Claims (1)

[Claims] The compressor consists of a compressor that causes periodic pressure fluctuations in the working gas in the working space, and a cold finger section that communicates with the working space of the compressor through a supply pipe. a piston reciprocably housed in the piston, the piston having one working surface that defines the volume of the working space;
The other actuating surface changes the volume of the buffer space, and the cold finger portion includes a movable body that reciprocates within the cold finger portion, a seal for the piston member that surrounds the piston member forming a part of the movable body, and It has a gas spring space separated from the working space by a seal for the piston member, and the movable body is driven by the differential pressure between the working space and the gas spring space, and the pressure in the working space is driven by the differential pressure between the working space and the gas spring space. In the refrigerator, the buffer space and the gas spring space are connected by a first connection circuit, and the buffer space and the working space are connected by a first connection circuit. are connected by a second connection circuit having a check valve in the middle, and the seal for the piston member is constituted by a gap seal that utilizes a narrow gap between the piston member and the housing forming the wall of the cold finger portion. death,
A refrigerator characterized in that a static pressure bearing is formed in the gap seal portion.