JP2713675B2 - Cooler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chiller, and more particularly to a gas chiller used for cooling an infrared device such as a Stirling cooler or liquefying air.

[0002]

2. Description of the Related Art FIG. 6 shows, for example, Japanese Patent Publication No. 54-28980.
FIG. 1 is a cross-sectional side view showing a schematic configuration of a conventional Stirling cycle gas cooler disclosed in Japanese Unexamined Patent Application Publication No. H10-115,026. In the figure,
Reference numeral 1 denotes a cylinder in which a piston 2 reciprocates. Reference numeral 3 denotes a cold finger, which includes a displacer 4 which reciprocates due to pressure fluctuations of the working gas, and a lower portion of which is connected to the cylinder 1 by a communication pipe 5.

The upper working surface 4 of the displacer 4
b forms a boundary with the expansion space 6, and this expansion space 6
The first compression space 7 between the lower working surface 4a of the displacer 4 and the communication pipe 5, the second compression space 8 between the upper working surface 2a of the piston 2 and the communication pipe 5, the displacer 4 Together with the heat storage device 9 provided therein and the space inside the communication pipe 5, an operation space is formed.

[0004] The regenerator 9 can communicate with the lower working gas through the center hole 10 and with the upper working gas through the center hole 11 and the radial flow duct 12. The machine also includes a freezer 13 as a heat exchanger for heat exchange between the expanded cold working gas and the object to be cooled.

[0005] A clearance seal 14 is disposed between the piston 2 and the wall of the cylinder 1 to prevent the flow of working gas between the buffer space 15 located below the piston 2 and the working space. ing. Further, a clearance seal 16 is provided between the displacer 4 and the cold finger 3 to force the flow of the working gas between the expansion space 6 and the first compression space 7 to flow in the heat storage device 9. ing.

The piston 2 is provided with a lightweight sleeve 17 made of a non-magnetic and non-magnetic material such as aluminum in the buffer space 15 below the piston 2. A coil 18 is formed by winding a conductor around the sleeve 17.
8 are connected to lead wires 19 and 20 passing through the wall of the cylinder 1, and these lead wires 19 and 20 are connected to the cylinder 1
Are connected to electrical terminals 21 and 22, respectively.

The coil 18 can reciprocate within an annular space 23 in the axial direction of the piston 2.
There is an armature magnetic field inside. The lines of force of the armature magnetic field extend in the radial direction crossing the moving direction of the coil 18. In this case, the permanent magnet is composed of an annular permanent magnet 24 having upper and lower magnetic poles, a soft iron annular disk 25, a soft iron cylinder 26 and a soft iron circular disk 27, which are integrally formed as a closed magnetic circuit, that is, a closed magnetic force line circuit. Is composed.

The sleeve 17, the coil 18, the lead wires 19 and 20, the annular space 23, the annular permanent magnet 24, the soft iron annular disk 25, the soft iron cylinder 26 and the soft iron circular disk 27 described above are all formed. Constitutes a linear motor 28 for driving the piston.

The piston 2 and the displacer 4 are respectively composed of a coil spring 29 serving as a resonance spring for the piston and a coil spring 30 serving as a resonance spring for the displacer.
Thereby, the piston 2 and the displacer 4 are engaged with the cylinder 1 and the cold finger 3 so as to be able to reciprocate, thereby defining a stationary position when the piston 2 and the displacer 4 are stationary and a neutral position during operation.

Next, the operation of the above-described conventional Stirling cycle gas cooler will be described. Electrical terminal 21,
AC power supply (not shown) equal to the resonance frequency of the system at 22
Is connected, a circumferential alternating current flows through the coil 18, and a periodic Lorentz force acts on the coil 18 in the axial direction due to the interaction between the alternating current and the radial magnetic field generated by the annular permanent magnet 24. As a result, the assembly comprising the piston 2, the sleeve 17 and the coil 18 and the system comprising the coil spring 29 for the piston come into resonance, and the assembly vibrates in the axial direction.

The vibration of the piston 2 is transmitted from the expansion space 6, the first compression space 7, the second compression space 8, the communication pipe 5, the heat storage 9, the center hole 10, the center hole 11, the radial flow duct 12 and the freezer 13. A periodic pressure change is caused to the working gas enclosed in the working space, and a periodic axial vibration force is generated in the displacer 4 by a change in the flow rate of the gas passing through the regenerator 9. In this way, the displacer 4 including the regenerator 9 reciprocates in the cold finger 3 in the axial direction at the same frequency as the piston 2 and at a different phase.

When the piston 2 and the displacer 4 move with an appropriate phase difference, the working gas enclosed in the working space constitutes a thermodynamic cycle known as a "reverse Stirling cycle" and mainly comprises an expansion space. 6 and the freezer 13 generate cold heat.

Regarding the above-mentioned "reverse Stirling cycle" and the principle of its generation of cold heat, reference is made to Clio Cooler Gy. Walker, Plenham Press, New York,
"Cryo cooler" (G. Walker, Pl
enum Press, New York, 1983, p
pp. 123-177).

The principle will be briefly described below.
The working gas in the second compression space 8 compressed by the piston 2 is cooled by the heat of compression while flowing through the communication pipe 5, and flows into the first compression space 7, the center hole 10, and the regenerator 9. The working gas is precooled by the cold stored in the regenerator 9 a half cycle before, and the working gas is further supplied to the center hole 11 and the radial flow duct 12
And enters the expansion space 6 through the freezer 13.

When most of the working gas enters the expansion space 6, expansion starts, and cold heat is generated in the expansion space 6. The working gas then returns in the flow path while discharging cold heat to the regenerator 9 in the reverse order, and enters the second compression space 8. At this time, heat is taken from outside in the freezer 13 to cool the outside. Thus, when most of the working gas returns into the second compression space 8, compression starts again, and the next cycle is started. By the above-described process, the above-mentioned “reverse Stirling cycle” is completed and cold heat is generated.

FIG. 7 shows a structure of a coil spring 29 which is a resonance spring mounted on a piston of the conventional cooler described in FIG. 7A is a top view, FIG. 7B is a side view, and FIG.
(C) is a bottom view. As shown in FIG.
9 is a central axis 32 at both ends of the coil spring due to its processing accuracy;
It is difficult to make 33 coincide with each other.
3 had eccentricity ε.

FIG. 8 shows details of a state in which a coil spring 29, which is a resonance spring for a piston of a conventional cooler, is attached to a piston. As shown in FIG. 8, in the conventional cooler, the coil spring 29 described in FIG.
, The center axes 32 and 3 at both ends of the coil spring are used.
3 has an eccentricity ε.

On the other hand, the clearance δ of the clearance seal 14 must be set to an extremely small value of about 10 to 20 μm in order to secure a predetermined sealing performance.
Is much larger than the clearance δ of the clearance seal 14. Therefore, when the piston 2 is mounted on the cylinder 1 which is coaxial with the lower central axis 33 of the coil spring 29,
Due to this eccentricity ε, a lateral restoring force F acts on the piston coil spring 29. The lateral restoring force F acts as a load for pressing the piston 2 against the cylinder 1.

Therefore, in order to reciprocate the piston 2 in a state where the pressing load is applied, the clearance seal 14 is required.
Wear occurs on the sliding surface between the cylinder 1 and the piston 2 which forms In order to minimize this wear,
One of the sliding surfaces of the cylinder 1 and the piston 2 constituting the clearance seal 14 is made of polytetrafluoroethylene (PTF) in which glass fiber or carbon fiber is added.
The sliding surface was formed by using the composite material prepared in E) and making the other mating surface of metal.

[0020]

Since the cooler according to the present invention is constructed as described above, the composite material to which glass fiber or carbon fiber is added damages the surface of the sliding counterpart material, In addition to roughening the surface roughness, harmful metal abrasion powder was generated with respect to the abrasion of the sliding portion, and sufficient abrasion resistance could not be secured.

In particular, the piston 2 and the cylinder 1 which form the clearance seal 14 due to the reciprocating motion of the piston 2 cannot withstand the high surface pressure required for a long life and miniaturization required for a recent cooler. The sliding surface of is significantly worn,
Gas leakage at the piston seal will increase,
There was a problem that a long-life cooling machine could not be obtained.

The coil spring 30, which is a resonance spring for the displacer, has a similar problem. The reciprocating motion of the displacer 4 causes the sliding surfaces of the displacer 4 and the cold finger 3 constituting the clearance seal 16 to be significantly worn, and There is a problem in that gas leakage at the seal portion increases, and a long-life cooler cannot be obtained.

The present invention has been made in order to solve the above-mentioned problems, and has little wear at a seal portion.
The purpose is to obtain a cooler with a long life.

[0024]

According to a first aspect of the present invention, there is provided a cooler comprising a polyparaoxybenzoyl and a polyparaoxybenzoyl on one of an inner peripheral surface of a cold finger and an inner peripheral surface of the cylinder constituting a clearance seal. A cylindrical liner made of a composite material composed of tetrafluoroethylene is provided, and the surface roughness of the outer peripheral surface of the displacer and the piston sliding with the cylindrical liner is calculated as a center line average roughness Ra.
And Ra is set to 0.05 μm or less.

According to a second aspect of the present invention, there is provided a cooler, wherein one of a displacer constituting a clearance seal and an outer peripheral surface of the piston is made of a composite material comprising polyparaoxybenzoyl and polytetrafluoroethylene. A cylindrical liner is provided, and the surface roughness of the cold finger sliding on the cylindrical liner and the inner peripheral surface of the cylinder is determined by a center line average roughness Ra, Ra = 0.0
It is set to 5 μm or less.

[0026]

According to the first or second aspect of the present invention, there is provided a cooler having a sliding surface constituting a clearance seal, for example, one of a cold finger and an inner peripheral surface of a cylinder, or
On either the displacer or the outer peripheral surface of the piston,
A cylindrical liner made of a composite material composed of polyparaoxybenzoyl and polytetrafluoroethylene, which are aromatic polyester resins, is provided, and a mating surface that slides with the cylindrical liner, for example, an outer peripheral surface of a displacer and a piston or The surface roughness of the inner peripheral surface of the cold finger and the cylinder is determined by the center line average roughness Ra, Ra = 0.05 μ
m or less, damages the surface of the mating material,
The surface roughness of the mating material is not roughened, and metal wear powder harmful to the wear of the sliding portion is not generated, so that the wear of the clearance seal is reduced and the life is extended.

[0027]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 31 denotes a cylindrical cylinder liner made of polytetrafluoroethylene to which polyparaoxybenzoyl is added, which slides with the piston 2 to form the clearance seal 14. Here, the surface roughness of the piston 2 is the center line average roughness Ra, Ra = 0.05 μm
Finished below.

In general, a polytetrafluoroethylene-based composite material using a polyimide resin or an aromatic polyester resin as a filler material has no abrasive property on the mating steel surface.
It is known as a sliding material that does not damage a soft mating material. Among the conventionally developed polytetrafluoroethylene-based sliding materials, the wear resistance is good, and
As a sliding material that does not damage a soft mating material, it is a composite material composed of polyparaoxybenzoyl, which is an aromatic polyester resin, and polytetrafluoroethylene.

FIG. 2 shows the results of a reciprocating wear test performed by the inventor focusing on this material. The test was performed with an outer diameter of 5 (m
m), a cylindrical test piece with a length of 7 (mm) is made of polytetrafluoroethylene to which 20% (Wt%) of polyparaoxybenzoyl is added, and its end surface is used as a sliding surface, and the surface roughness of the mating material is used as a parameter. did.

The test conditions were as follows: the atmosphere was helium gas;
The contact surface pressure is 0.25 (MPa), and the average sliding speed is 0.
6 (m / sec), the total friction time was 100 hours, and stainless steel was used as the mating material. In FIG. 2, the horizontal axis is the surface roughness of the stainless steel as the mating material, Ra (μm).
And the vertical axis represents polyparaoxybenzoyl at 20 (Wt).
%) Shows the specific wear of the added polytetrafluoroethylene.

Here, the specific wear amount Ws (mm ³ / N · m)
Is given by: Ws = V / (P · L) V: Wear volume (mm ³ ) P: Load (N) L: Friction distance (m) From FIG. 2, it can be seen that the specific abrasion amount of polytetrafluoroethylene to which polyparaoxybenzoyl is added tends to rapidly increase when the surface roughness of the mating material becomes Ra = 0.05 (μm) or more. The specific wear amount in a region where the surface roughness is Ra = 0.05 (μm) or less is Ws = 1 to 2 × 10 ⁻⁷ (mm ³ / N · m).
It can be seen that the wear range is extremely small.

In FIG. 2, for the sake of comparison, the surface roughness of the mating material before the test under the same test conditions was Ra =
The measurement results of the specific wear amount of polytetrafluoroethylene containing glass fiber, which was set at 0.01 to 0.02 (μm), are also shown. From FIG. 2, the specific wear amount of polytetrafluoroethylene containing glass fiber is Ws = 3.
５5 × 10 ⁻⁷ (mm ³ / N · m), indicating that the abrasion is greater than that of polytetrafluoroethylene to which polyparaoxybenzoyl is added.

Hereinafter, the present embodiment will be described. In the present embodiment, the surface roughness of the piston 2 is determined by the center line average roughness R
In a, finish below Ra = 0.05 .mu.m, La for cylindrical cylinder made of polytetrafluoroethylene was added poly-p-oxybenzoyl Lee na 31 cylinders 1
Is provided on the inner peripheral surface, the wear of the sliding surface of the clearance seal 14 is reduced, and the life of the cooler can be extended.

The operation principle of the cooler shown in the present embodiment is exactly the same as that of the conventional example, and therefore will not be described here.

Embodiment 2 FIG. In Example 1 above, the surface roughness of the piston 2 was finished to have a center line average roughness Ra of Ra = 0.05 μm or less, and a cylindrical shape made of polytetrafluoroethylene in which polyparaoxybenzoyl was added to the inner peripheral surface of the cylinder 1. the cylinder la Lee Na 31 has been described structure provided on the inner surface of the cylinder 1, the center line average roughness Ra of the surface roughness of the displacer 4, as shown in Figure 3, Ra = 0.05 .mu.m
m or less, and a cylindrical cold finger liner 32 made of polytetrafluoroethylene with polyparaoxybenzoyl added to the inner peripheral surface of the cold finger 3.
Is provided, the wear of the sliding surface of the clearance seal 16 is reduced, and the life of the cooler is extended.

Embodiment 3 FIG. In the first embodiment, the piston 2
Is the center line average roughness Ra, Ra = 0.0
A cylindrical cylinder liner 31 made of polytetrafluoroethylene with polyparaoxybenzoyl added to the inner peripheral surface of cylinder 1
As shown in FIG. 4, the surface roughness of the inner circumferential surface of the cylinder 1 is finished to Ra = 0.05 μm or less with the center line average roughness Ra as shown in FIG. A circumferential piston liner 33 made of polytetrafluoroethylene to which polyparaoxybenzoyl is added may be provided, and the same effect as in the first embodiment can be obtained.

Embodiment 4 FIG. In the second embodiment, the surface roughness of the outer peripheral surface of the displacer 4 is determined by the center line average roughness Ra,
Finished to Ra = 0.05μm or less, cold finger 3
5 shows a structure in which a cylindrical cold finger liner 32 made of polytetrafluoroethylene to which polyparaoxybenzoyl is added is provided on the inner peripheral surface of FIG.
As shown in the figure, the surface roughness of the inner peripheral surface of the cold finger 3 is finished to Ra = 0.05 μm or less with the center line average roughness Ra, and the outer peripheral surface of the displacer 4 is made of polytetrafluoroethylene to which polyparaoxybenzoyl is added. A cylindrical displacer liner 34 may be provided, and the same effects as those of the second embodiment can be obtained.

Embodiment 5 FIG. In the above embodiment, a cylindrical liner made of a composite material consisting of polyparaoxybenzoyl, which is an aromatic polyester resin, and polytetrafluoroethylene is provided on a sliding surface constituting a clearance seal of a Stirling cooler, The surface roughness of the mating material sliding with this liner is defined as the center line average roughness Ra, Ra = 0.0
Although the case where it is set to 5 μm or less is shown, for example,
It may be applied to sliding parts of other types of coolers that slide in a dry state such as Gifford McMahon cycle, or sliding parts such as bearings that slide in a general dry state, as in the above embodiment. Has the effect of

[0039]

As described above, according to the first or second aspect of the present invention, the sliding surface forming the clearance seal is made of a composite comprising polyparaoxybenzoyl, which is an aromatic polyester resin, and polytetrafluoroethylene. A cylindrical liner made of a material is provided, and the surface roughness of the mating surface that slides with the cylindrical liner is determined by the center line average roughness Ra.
Since Ra is set to 0.05 μm or less, the wear of the sliding surface forming the clearance seal is reduced, and a long-life cooler can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a cooler according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram showing a wear test result.

FIG. 3 is a partial sectional view showing a cooler according to Embodiment 2 of the present invention.

FIG. 4 is a partial sectional view showing a cooler according to Embodiment 3 of the present invention.

FIG. 5 is a partial sectional view showing a cooler according to Embodiment 4 of the present invention.

FIG. 6 is a sectional view showing a conventional cooler.

FIG. 7 is a structural view of a coil spring mounted on a conventional cooler.

FIG. 8 is a detailed view of a state where a coil spring is mounted in a conventional cooler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Cold finger 4 Displacer 5 Communication pipe 14 Clearance seal 16 Clearance seal 29 Coil spring (resonant spring for piston) 30 Coil spring (resonant spring for displacer) 31 Liner for cylinder (cylindrical liner) 32 For cold finger Liner (cylindrical liner) 33 Liner for piston (cylindrical liner) 34 Liner for displacer (cylindrical liner)

Claims (2)

(57) [Claims] A displacer housed in a cold finger filled with a working gas and reciprocally engaged with said cold finger by a displacer resonance spring;
A clearance seal is provided for a cooler having a piston housed in a cylinder filled with a working gas and reciprocally engaged with the cylinder by a piston resonance spring, and a communication pipe communicating the cold finger and the cylinder. A cylindrical liner made of a composite material composed of polyparaoxybenzoyl and polytetrafluoroethylene is provided on one of the inner peripheral surface of the cold finger and the inner peripheral surface of the cylinder. The surface roughness of the outer peripheral surface of the displacer and the piston sliding with the liner is represented by a center line average roughness Ra, Ra = 0.05 μm
A cooling machine characterized by the following settings. 2. A displacer housed in a cold finger filled with a working gas and reciprocally engaged with said cold finger by a displacer resonance spring.
A clearance seal is provided for a cooler having a piston housed in a cylinder filled with a working gas and reciprocally engaged with the cylinder by a piston resonance spring, and a communication pipe communicating the cold finger and the cylinder. A cylindrical liner made of a composite material consisting of polyparaoxybenzoyl and polytetrafluoroethylene is provided on one of the outer peripheral surfaces of the displacer and the piston, and the cylindrical liner slides with the cylindrical liner. A cooler characterized in that the surface roughness of the cold finger and the inner peripheral surface of the cylinder is set to be Ra = 0.05 μm or less as a center line average roughness Ra.