JPH0250052A - Freezer - Google Patents

Abstract

PURPOSE:To reduce a friction of a sliding liner of a compressor and provide a long life of it even if a freezer is operated for a long period of time by a method wherein the sliding liner made of polytetrafuloroethylene resin (PTFE) added with aromatic polyester is arranged at an inner circumferential surface of a cylinder or an outer circumferential surface of a piston of the compressor. CONSTITUTION:Either one of an inner circumferential surface of a cylinder 4 of a compressor 1 or an outer circumferential surface of a piston 15 is provided with a cylindrical sliding liner 12 made of PTFE added with aromatic polyester. Aromatic polyester added with PTFE enforces PTFE and prevents a wear of PTFE and at the same time its hardness is not so high as that of glass fiber or carbon fiber, so that it may not damage a surface of a piston 5 acting as a sliding partner during its operation. Due to this fact, the damaged surface of the piston 5 may wear PTFE of the sliding liner 12, a clearance between the sliding liner 12 and the piston 5 is expanded and gas is leaked during compression and expansion, resulting in that a performance of a freezer may not be deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Stirling refrigerator that cools an infrared detection element to an extremely low temperature, for example.

[Conventional technology]

FIG. 3 shows an example of the configuration of a conventional Stirling refrigerator. The Stirling refrigerator shown in the figure is called a split type Stirling refrigerator, and is a typical example of a Stirling refrigerator.

In FIG. 3, the split type Stirling refrigerator is broadly divided into a compressor (1), cold fingers (21), and a connecting pipe +31 connecting them.

The compressor il+ includes a cylinder (4) and a piston (5).

The piston (5) is driven by an electric rotary motor (not shown) via a connecting rod (6) and a crank (71) to reciprocate inside the cylinder (4).

There is also an example in which the piston is directly driven by a reciprocating linear motor without using the connecting rod (6) or crank (7) as shown in Fig. 3. A head (8) is attached to the cylinder (4) and the piston (5).
) and the internal space defined by the cylinder head (8) is called a compression chamber (9). Mechanical members such as the crank (7) that drive the piston (5) are housed in an aluminum housing αυ, and the space inside the Harajingumi O, which is partitioned from the compression chamber (9) by the piston (51), is housed in an aluminum housing αυ. The cylinder (41), the cylinder head (8), and the housing αG are joined to each other so as to maintain airtightness with the outside, and the compression chamber (9) and the bulk chamber αυ inside are For example, a high-pressure working gas such as helium or hydrogen is sealed.

In the case of a Stirling refrigerator, when oil is used to lubricate the parts of the cylinder (4) and the piston (5) that slide against each other, the oil is deposited on the inner surface of the low temperature cylinder α of the cold finger (2), which will be explained later. Oil is generally not used because it can freeze and cause operational problems. Therefore, as shown in Fig. 3, a sliding liner a''a made of self-lubricating resin is attached to the inner peripheral surface of the cylinder (4) with adhesive so that it can slide smoothly even when oil is used. The material of the sliding liner C1 is mainly composed of polytetrafluoroethylene resin (hereinafter referred to as PTKE).
In order to reduce the wear of PTFE, materials to which glass fiber or carbon fiber is added as a reinforcing material are often used.

on the other hand.

The piston +51 is generally made of metal and has a smooth surface with a surface roughness of 1 μm or less to prevent wear of the sliding liner. The gap between the two is, for example, 10μ to make it difficult for the
It must be as small as m or less. Further, the outer surface of the cylinder (4) is provided with fins αJ for enhancing heat dissipation to the outside. The above is the configuration of the compressor fil. On the other hand, the cold finger (2) has a cylindrical low-temperature cylinder I, and has a displacer that slideably reciprocates within the low-temperature cylinder I. The space inside the low temperature cylinder I is filled with the displacer (15
The displacer (13
The upper space is a cold room US, and the lower space is a high temperature room (l
Call it η. A regenerator U and a gas passage hole αg are provided inside the displacer housing, and the low temperature chamber αe and the high temperature chamber are connected to the regenerator! ie through the gas passage hole +19, and the regenerator +18 is filled with a cold storage material (2) such as a copper wire mesh. A seal ring I21 is provided on the side of the displacer to prevent the working gas from passing through the gap between the low temperature cylinder αψ and the displacer I19! is inserted.

A control cylinder and a control chamber are provided at the lower part of the cold finger (2), and the control piston (■) attached to the lower end of the displacer α passes through the high temperature room riη and the control cylinder (■). protrudes into the control room (2). The control cylinder (■) and the control piston (c)
! A seal ring (2) is attached to the control cylinder so that the working gas does not pass through the gap (4).Each chamber of the cold finger (2) is filled with, for example, helium, similarly to the compressor (1).

It is filled with high-pressure working gas such as hydrogen. The above is the configuration of the cold finger (2), and the compressor fil
The compression chamber (91) and the high temperature chamber fin of the cold finger (2) communicate with each other via the connecting pipe (3).

The compression chamber (9), the space inside the connecting pipe (31), the low temperature chamber (Il!), the high temperature chamber crt, the regenerator α11
> and the gas passage hole α9 are in communication with each other, and the entirety of these chambers is collectively referred to as the working chamber (2).

The operation of the conventional refrigerator configured as described above will be explained. By moving back and forth inside the cylinder (4), the piston (5) gives a sinusoidal wave to the gas pressure in the working chamber (2) extending from the compression chamber (9) to the cold room ae. On the other hand, the volume of the bulk chamber (Il+) is sufficiently larger than the stroke volume of the piston (5), so the internal gas pressure is
The seal ring attached to the cold finger (21 control cylinder), which does not change much even when the cylinder moves back and forth, is sensitive to short-period pressure changes like the pressure waves in the gas in the working chamber. The gas pressure in the control chamber is maintained at approximately the average value of the gas pressure in the working chamber, since the sealing is incomplete over a long period of time.

FIGS. 4 to 7 explain the operating principle of the conventional device in the order of the refrigeration cycle.

In one process of the cycle shown in Figure 4, the compressor +1
The piston (5) of 1 is located below in the cylinder (4), and the displacer ttcj of the cold finger (2) is located above the cold cylinder I.
While reaching the figure, the piston (5) rises and compresses the gas in the working chamber (2). The heat generated by this compression is transferred to the cylinder (
5) is emitted to the outside from the fin 0 on the outer periphery. At the time shown in Figure 5, the gas pressure in the working chamber (2) has become greater than the gas pressure in the control chamber (2).

The downward force generated on the control piston Q41 by this differential pressure overcomes the static frictional force of the seal rings an and (2) and begins to move the displacer fi+3 downward.

As shown in FIG. 6, it is moved to the lower part of the low temperature cylinder a4. As the displacer α moves, the gas in the high temperature chamber αη passes through the regenerator a1G and moves to the low temperature chamber αG.

At this time, the cold storage material (2) filled in the regenerator α9 absorbs heat from the gas passing therethrough and lowers the temperature of the gas. In the process from Figure 6 to Figure 1, the piston (5) of the compressor ill
falls and expands the gas in the working chamber (2), and this expansion causes the temperature of the gas in the cold room αe to further drop, absorbing heat from the surroundings of the upper part of the cold finger. This endothermic action plays the role of terminating the object as a refrigerator. In the working chamber (2), the gas pressure decreases due to the expansion of the gas, so at the time of FIG. 7, the gas pressure is greater in the control chamber than in the working chamber (2). Due to this differential pressure, the force K applied upward to the control piston (■) overcomes the static frictional force of the seal ring Q11 and the mouth, and begins to move the displacer αS upward, moving it to the upper part of the low temperature cylinder t141 as shown in Fig. 4. . As the displacer ri9 moves, the low temperature gas in the cold room αe passes through the regenerator aS, and the regenerator αS
While the cold energy is stored in the cold storage material ω inside, the gas itself flows into the high temperature chamber while increasing its temperature. By repeating the above cycle.

Refrigeration operation is performed.

[Problem to be solved by the invention]

The conventional device as described above has the following problems. That is, the sliding liner a3 provided in the cylinder (4) is made of PTFE reinforced by adding glass fiber or carbon fiber, as described above, but glass fiber and carbon fiber have high hardness. As a result, the surface of the piston (5), which is the sliding partner, is damaged. piston(
5) When the scratches on the surface increase and the surface becomes rough, PTF
The amount of wear on E increases, and the piston (5) and sliding liner fi
The gap l gradually increases. As this gap increases, when the piston compresses and expands gas, the amount of gas leaking from this gap increases, leading to early deterioration in the performance of the refrigerator. In other words, the conventional device had a problem in that the sliding liner (13) wore out quickly, resulting in a short service life.

The present invention has been made to solve these problems, and proposes a long-life refrigerator in which the sliding liner (2) is less worn out even when operated for long periods of time.

[Means to solve the problem]

The refrigerator according to the present invention is provided with a sliding liner made of PTFE with aromatic polyester added as a reinforcing material on either the inner peripheral surface of the cylinder or the outer peripheral surface of the piston.

[Effect]

In this invention, aromatic polyester strengthens PTFE and has the role of preventing wear of PTFE, but since its own hardness is low, it does not damage the surface of the sliding partner, so it does not damage the surface of the sliding partner. Therefore, wear of the PTFE is not accelerated, and a refrigerator with a long life can be realized.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention.

The cold finger (2) and the connecting pipe (3) are exactly the same as the conventional device shown in Fig. The only difference from the conventional device is liner T1.

In the embodiments described above, the principle of generating refrigeration is exactly the same as the conventional apparatus shown in FIGS. 3 to 7. However, the aromatic polyester added to PTFE is similar to glass fiber and carbon fiber, which fail in conventional equipment.
While having the effect of strengthening the PTFE and preventing wear, glass fibers and carbon fibers do not have high hardness, so they do not damage the surface of the piston (5), which is the sliding partner during operation. Therefore, unlike the conventional device, the damaged surface of the piston 15+ wears out the PTFE of the sliding liner t1'a, and the gap between the sliding liner a'a and the piston (5) widens, causing gas to leak during compression and expansion. Since the performance of the refrigerator does not deteriorate due to leakage, a refrigerator with a long life can be realized.

In the embodiment shown in Fig. 1, the cylinder (4) was provided with a sliding liner a3 made of PTF'E containing aromatic polyester, but as shown in Fig. 2, the piston (5) The invention can also be practiced by providing a sliding liner a'a made of PTFE doped with aromatic polyester and by making the surface of the cylinder (4) metal.

Incidentally, in the above explanation, the case where the present invention is applied to a split type Stirling refrigerator has been described, but it goes without saying that the present invention can also be applied to other known Stirling refrigerators.

〔Effect of the invention〕

This invention has the effect of extending the life of the refrigerator through a simple structure in which a sliding liner made of polytetrafluoroethylene resin containing aromatic polyester is provided on the inner peripheral surface of the cylinder or the outer peripheral surface of the piston. There is.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing an embodiment of the present invention. FIGS. 3 to 7 are diagrams showing conventional refrigerators. In the figure, (1) is a compressor, (4) is a cylinder, +
51 is a piston, fi5 is a sliding liner, and α is a low temperature cylinder. a9 is a displacer, αe is a low temperature chamber, and αη is a high temperature chamber. aδ is a regenerator, and ■ is a cold storage material. Note that in FIG. 1, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Scope of Claims] A compressor including a cylinder, a piston that repeatedly compresses and expands gas by reciprocating in the cylinder, an elongated cylindrical low-temperature cylinder, and an interior of the low-temperature cylinder. a displacer that partitions the room into a high-temperature chamber and a low-temperature chamber, and that reciprocates inside the low-temperature cylinder;
An inner circumferential surface of the cylinder in a refrigerator including a regenerator provided inside the displacer, communicating the low temperature chamber and the high temperature chamber, and storing a cold storage material therein. Alternatively, a refrigerator characterized in that a cylindrical sliding liner made of polytetrafluoroethylene resin to which aromatic polyester is added is provided on either one of the outer circumferential surfaces of the piston.