JP2003294333A - Stirling engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent oxidation of internal key parts due to continuous operation of a Stirling engine, the performance deterioration and failure due to icing of humid moisture by removing residual air (oxygen) and residual moisture inside of a casing. <P>SOLUTION: This Stirling engine has an expansion space 2, a compression space 8, and a bounce space 14 in the casing 13 filled with a hydraulic fluid, and is formed by arranging at least one of porous materials including one or both of an oxygen scavenger for removing the oxygen and a dehumidifying agent for removing the moisture in at least one position of porous material arranging positions 26, 27, and 28 in the casing. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Stirling engine such as a Stirling engine for generating power and a Stirling refrigerator used for low temperature generation.

[0002]

2. Description of the Related Art In recent years, the Stirling engine has attracted attention from the viewpoint of energy saving and environmental problems. The Stirling engine is an external combustion engine that realizes a Stirling cycle, which is a reversible cycle, using an external heat source, and is more energy-saving than an internal combustion engine that requires highly flammable or ignitable fuel such as gasoline. It is a heat engine with the advantage of low pollution.

A Stirling refrigerator is widely known as an application example of this Stirling engine. This Stirling refrigerator is a refrigerator that generates a cryogenic temperature by using a reverse Stirling cycle. Hereinafter, a general structure of a Stirling engine will be described by exemplifying a free piston Stirling refrigerator, which is one application example of the Stirling engine.

As shown in FIG. 2, the Stirling refrigerator has a cylinder 10 in which an inert gas such as hydrogen or helium is filled as a working gas. A piston 9 and a displacer 7 are fitted and inserted in the cylinder 10, and a space inside the cylinder 10 is divided into a compression space 8 and an expansion space 2 by these. Normal,
The cylinder around the displacer 7 is a separate member from the cylinder 10 around the piston 9 to form a cylindrical bobbin 15. The piston 9 is driven by a linear motor 18, but since it is connected to the main body casing 13 by a spring 11, it makes a periodic sine motion in the cylinder 10. Further, the displacer 7 reciprocates in the cylinder 10 by receiving the force of the sine movement of the piston 9, but like the piston 9, since it is connected to the main body casing 13 by the spring 12, the displacer 7 takes a periodic sine movement. It will be. The sine motion of the piston 9 and the sine motion of the displacer 7 are performed in the same cycle with a constant phase difference during the steady operation.

A regenerator 4 is arranged between the compression space 8 and the expansion space 2, and by communicating these two spaces through the regenerator 4, a closed circuit is formed in the refrigerator. There is. A heat radiating heat exchanger 5 is attached to the compression space 8 side of the closed circuit, and the heat radiating heat exchanger 5 is further attached.
A radiator 6 is provided adjacent to. On the other hand, the heat absorbing heat exchanger 3 is attached to the expansion space 2 side of the closed circuit, and the heat absorbing device 1 is provided adjacent to the heat absorbing heat exchanger 3.

The working gas in the closed circuit flows in accordance with the operation of the piston 9 and the displacer 7, whereby the reverse Stirling cycle is realized. here,
The radiator 6 plays a role of releasing the heat in the compression space 8 to the outside, and the radiation heat exchanger 5 plays a role of promoting this radiation. Further, the heat absorber 1 plays a role of transferring external heat into the expansion space 2, and the heat absorbing heat exchanger 3 plays a role of promoting this heat transfer.

Next, the operation of the Stirling refrigerator having the above structure will be described. First, the linear motor 18 is operated to drive the piston 9. The piston 9 driven by the linear motor 18 approaches the displacer 7,
The working gas in the compression space 8 is compressed. As a result, the temperature of the working gas in the compression space 8 rises, but the heat generated in the compression space 8 by the radiator 6 is released to the outside via the heat dissipation heat exchanger 5. The temperature of the working gas therein is maintained substantially isothermal. That is, this process constitutes the isothermal compression process of the reverse Stirling cycle.

Next, the working gas compressed by the piston 9 in the compression space 8 flows into the regenerator 4 by its pressure and is further sent to the expansion space 2. At that time, the heat quantity of the working gas is stored in the regenerator 4. That is, this process constitutes an equal volume cooling process of the reverse Stirling cycle.

Subsequently, the high-pressure working gas flowing into the expansion space 2 expands as the displacer 7 moves to the right in the drawing. As a result, the temperature of the working gas in the expansion space 2 decreases, but since the external heat is transferred to the expansion space 2 by the heat absorber 1 via the heat absorbing heat exchanger 3, the inside of the expansion space 2 is almost It is kept isothermal. That is, this process constitutes the isothermal expansion process of the reverse Stirling cycle.

Eventually, the displacer 7 begins to return to the left in the drawing, so that the working gas in the expansion space 2 passes through the regenerator 4 and returns to the compression space 8 again. At that time, the amount of heat accumulated in the regenerator 4 is given to the working gas, so that the working gas is heated. That is, this process is
It constitutes the equal volume heating process of the reverse Stirling cycle.

The reverse Stirling cycle is constructed by repeating this series of processes (isothermal compression process-isovolume cooling process-isothermal expansion process-isovolume heating process). As a result, the heat absorber 1 gradually lowers in temperature and reaches an extremely low temperature.

[0012]

Generally, in a Stirling engine, high pressure helium or hydrogen gas is used as a working gas filled in a casing.
In the conventional structure and assembling process, there has been a problem how to reduce residual air and moisture components mixed in other than the original gas components. For example, in the assembly of the Stirling refrigerator shown in the above example, when the high-pressure helium that is the working gas is finally filled into the sealed casing 13, the internal air is once sufficiently evacuated, and then the helium gas is removed. The method of introducing is commonly used. However, due to the operating principle of the Stirling refrigerator, a sealability between the piston portion 9 and the cylinder portion 10 is required, so the bounce space in which the magnet 17, the linear motor assembly 18, the piston spring 11 and the displacer spring 12 are arranged. In part 14, there were many cases where this gas replacement was insufficient.

In many parts of the Stirling refrigerator, a resin material is used because of its advantages such as light weight and low processing cost. For example, a PET (polyethylene terephthalate) film is used as the base material of the regenerator 4, and a polycarbonate material is used for the tip end cap portion of the displacer 7. Since such a resin material also has a high hygroscopic property, a drying process such as deaeration while drawing a vacuum is generally performed in assembling a Stirling refrigerator. Such a process has a problem that it takes time and leads to an increase in manufacturing cost. In addition, due to the complicated internal assembly structure of individual parts inside the Stirling refrigerator and the seal structure as described above, it is difficult to take sufficient measures against deaeration and dehumidification despite the introduction of the vacuum deaeration process. Was becoming. As a result, when the Stirling refrigerator is continuously operated due to residual air (oxygen) and residual moisture, the temperature rises in the compression space 8 and the bounce space 14 also overlap, and the magnet portion made of a rare earth magnet and the steel material. This caused corrosion in the piston spring 11 and the displacer spring 12 based on, and caused performance deterioration and failure. Also,
The expansion space 2 where the water mixed in the working fluid becomes low temperature
This also led to the occurrence of problems such as deterioration of the refrigerator performance due to the freezing of the inside, which impedes the flow of the working gas particularly near the regenerator film.

The present invention has been made in view of the above-mentioned conventional problems, and by removing residual air (oxygen) and residual moisture inside the casing, oxidation of internal basic components due to continuous operation of the Stirling engine and The purpose is to prevent performance deterioration and failure due to moisture, moisture, and freezing.

[0015]

A Stirling engine of the present invention is a Stirling engine having an expansion space, a compression space and a bounce space in a casing filled with a working fluid, and removes oxygen in the casing. At least one of an oxygen removing material, a dehumidifying material that removes moisture (moisture), and an oxygen moisture removing material that removes oxygen and moisture is arranged. According to this configuration, one or both of the air (oxygen) component and the moisture content mixed as a residual component in the working fluid filled in the casing are removed. As a result, it is possible to prevent malfunction due to deterioration over time due to corrosion of internal parts of the Stirling engine and performance deterioration due to condensation and freezing of residual water.

The oxygen scavenger may be a porous material containing an oxygen scavenger, for example, a filter through which air flows through the porous material. Further, it is not necessary for air to circulate therethrough as in the case of a filter, and it suffices that the surface area can be increased to effectively remove oxygen.
As for the dehumidifying material, the porous material containing the dehumidifying agent may be a porous material containing the dehumidifying agent, for example, a filter having air passing through the porous material. Further, it is not necessary for air to circulate therethrough as in the case of a filter, and it suffices that the surface area can be increased and dehumidification can be effectively performed. Further, both a deoxidizer and a dehumidifier may be contained in one porous material. When one or both of the deoxidizing material and the dehumidifying material are made into a filter shape, it is desirable to dispose the filter-like porous material over the passage cross section of the working fluid.

Further, in the Stirling engine according to the above aspect, it is desirable that at least one of the oxygen removing material, the dehumidifying material and the oxygen moisture removing material is disposed in the bounce space. With this configuration, air (oxygen) that remains as a residual component that cannot be sufficiently replaced with the working fluid in the bounce space due to the sealability between the piston and cylinder, and the moisture adsorbed on each component, is used as an oxygen absorber or dehumidifier. Can be removed by Therefore, it is possible to prevent the wear and deterioration of the magnet assembly and the steel spring-based piston springs and displacer springs arranged in the bounce space by anticorrosion. As a result, stable continuous operation can be performed and long-term reliability can be obtained.

In the Stirling engine, it is desirable that at least one of the oxygen removing material, the dehumidifying material and the oxygen moisture removing material is arranged on the high temperature space side, for example, on the compression space side in a Stirling refrigerator. . In general, residual air (oxygen) and residual moisture adsorbed on internal parts and housings are more likely to be released as the temperature rises, so in an operating Stirling refrigerator, the expansion space where the temperature becomes relatively high. Further, by arranging a deoxidizer or a dehumidifier that removes residual gas components, it is possible to effectively remove oxygen and water and suppress mixing into the working fluid gas. As a result, adverse effects on performance due to oxidative deterioration of components inside the Stirling engine and condensation and freezing of residual water can be suppressed.

Further, in the Stirling engine, it is preferable that at least one of the oxygen removing material, the dehumidifying material and the oxygen moisture removing material is disposed on the working fluid flow passage between the expansion space and the compression space. . As a result, for example, in a Stirling refrigerator, residual water is removed on the flow path until the working gas moves to the expansion space on the low temperature side. Therefore, it is possible to prevent the performance of the refrigerator from deteriorating due to condensation of water and freezing in the expansion space or the expansion space side of the regenerator that serves as a gas flow path.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Here, also, as an application example of the Stirling engine, a free piston type Stirling refrigerator is exemplified and described.

FIG. 1 is a schematic sectional view of a Stirling refrigerator according to the present invention. In addition, in FIG.
The same members as those of the conventional Stirling refrigerator shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

At least one of the oxygen removing material of the porous material, the dehumidifying material of the porous material and the oxygen moisture removing material of the porous wet material according to the present invention is, as illustrated in FIG. 1, in the bounce space 14. The porous material arranging place 28, the porous material arranging place 27 in the expansion space 8 and the porous material arranging place 26 in the cylindrical bobbin 15 around which the regenerator film 4 is wound are arranged.

When at least one of the porous materials containing one or both of the oxygen scavenger and the dehumidifier is disposed at the porous material disposition place 28 in the bounce space 14, the magnetic energy located in the bounce space is It is possible to suppress corrosion of magnet assemblies 17 using an excellent rare earth-iron-based material and parts made of easily oxidizable materials such as a piston spring 11 and a displacer spring 12 based on steel.

In the Stirling refrigerating machine, the working gas such as high pressure helium or hydrogen gas is hermetically sealed in the casing 13.
Need to be filled inside. For this reason, in the assembly process of the refrigerator, a method is generally performed in which helium gas is introduced after the internal air has been sufficiently evacuated. However,
In the Stirling refrigerator, the piston portion 9 and the cylinder portion 1
Since the sealing property of 0 is required, gas replacement from the inside of the bounce space 14 becomes insufficient, and air (oxygen) and water other than the working gas tend to remain particularly in this space. However, by enclosing a porous material containing a deoxidizer and a dehumidifier in the bounce space, such residual gas components are removed. As a result, wear deterioration due to corrosion prevention of internal parts is suppressed, and long-term reliability that enables stable continuous operation is obtained.

Further, when at least one of the porous materials containing one or both of the oxygen scavenger and the dehumidifier is disposed at the porous material arranging place 27 in the compression space 8, the temperature in the compression space is relatively high. As a result, residual air (oxygen) and residual moisture adsorbed on the parts and housing are easily released. By arranging a deoxidizer or dehumidifier that removes residual gas components in this space, oxygen and water are effectively removed,
It becomes possible to suppress mixing into the working fluid gas. As a result, adverse effects on performance due to oxidative deterioration of internal components of the Stirling engine and condensation and freezing of residual water can be suppressed.

Further, when the porous material containing the dehumidifying agent is arranged at the porous material arranging place 26 on the outer periphery of the cylindrical bobbin 15 which is on the flow passage of the working fluid between the expansion space and the compression space, the operation is performed. Residual water is removed in the middle of the flow path until the gas moves to the expansion space on the low temperature side. Therefore, it is possible to prevent the performance of the refrigerator from deteriorating due to the condensation and freezing of water in the expansion space where the temperature becomes relatively low and the expansion space side of the regenerator.

As a material for the oxygen scavenger, active iron oxides such as ferrous oxide, ferric oxide and iron hydroxide are used. Also, oxidation of active organic substances such as vitamin C and alcohols can be used. When arranged in a Stirling refrigerator, it can be easily incorporated by immobilizing the oxygen absorbent on a resin to form a sheet or plate.

Materials such as silica gel, calcium oxide and calcium chloride are used as the material of the dehumidifying agent.

[0029]

(Example 1) As an example of the present invention, a porous material composed of the above materials was incorporated, and the conventional vacuum degassing and drying step was omitted, and the Stirling refrigeration shown in FIG. 1 was omitted. I assembled the machine. As the porous material, those obtained by sintering fine powders of the above materials, pressure-molded, impregnated with the fine powders using a thermoplastic resin as a binder, and the like were used. On the other hand, for comparison, the conventional Stirling refrigerator shown in FIG. 2 was assembled by vacuum deaeration and drying for 4 hours during the assembly process without using the porous material. With respect to both of the above Stirling refrigerators, the deterioration conditions of internal parts were compared after continuous 2000 hours of operation under severe operating conditions of a heat absorber temperature of -15 ° C, a radiator temperature of 49 ° C, and a piston amplitude of 6 mm.

As a result, in the conventional Stirling refrigerator, the oxidation of the magnet and the surface oxidation of the heat dissipation heat exchanger made of copper were confirmed. On the other hand, in the Stirling refrigerator in which the porous material according to the present invention is incorporated, no corrosion deterioration of parts was observed.

Example 2 Twenty prototypes similar to the structure of the present invention in Example 1 were assembled by omitting vacuum deaeration and drying. In addition, 20 Stirling refrigerators having the conventional structure in Example 1 were vacuum-deaerated and dried to make 20 prototypes. In the conventional structure of the Stirling refrigerator, in the initial performance evaluation, in two of the 20 units, the cooling capacity was obviously reduced due to the freezing in the expansion space. On the other hand, in the Stirling refrigerator incorporating the porous material according to the present invention, even though the vacuum deaeration and drying was omitted, none of the above cooling defects occurred.

Thus, by incorporating at least one of the porous materials containing one or both of the oxygen scavenger and the dehumidifier according to the present invention into a Stirling refrigerator,
It is possible to remove residual gas such as residual air and residual moisture, which leads to component deterioration and performance deterioration. Therefore, a highly reliable Stirling refrigerator can be realized. Further, as is clear from the above, since the vacuum degassing and drying step can be omitted from the conventional assembling step, it is possible to realize a significant reduction in assembling time and cost reduction.

Although the free piston type Stirling refrigerator is described as an example in the above-described embodiments and examples, it goes without saying that the present invention can be applied to a Stirling engine having a reverse cycle to the Stirling refrigerator. The embodiments and examples of the present invention disclosed above are illustrative in all points and not restrictive. The technical scope of the present invention is defined by the description of the claims, and includes the meaning equivalent to the description of the claims and all modifications within the scope.

[0034]

According to the present invention, at least one of a porous material containing one or both of a deoxidizing agent for removing oxygen and a dehumidifying agent for adsorbing moisture is provided in the casing of a Stirling engine. As a result, the air (oxygen) component and the moisture content mixed as the residual component in the working fluid filled in the casing are removed. Therefore, it is possible to prevent malfunction due to deterioration over time due to corrosion of internal parts of the Stirling engine and performance deterioration due to condensation and freezing of residual water. Furthermore, it is possible to omit the vacuum degassing and drying process, which can shorten the assembly process and realize the cost reduction of the Stirling engine.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a Stirling refrigerator according to the present invention.

FIG. 2 is a schematic sectional view of an example of a conventional Stirling refrigerator.

[Explanation of symbols]

1 heat absorber, 2 expansion space, 3 heat exchanger for heat absorption, 4
Regenerator, 5 Heat radiating heat exchanger, 6 Radiator, 7 Displacer, 8 Compression space, 9 Piston, 10 Cylinder, 11 Piston spring, 12 Displacer spring, 13 Main body casing, 14 Bounce space, 15
Cylindrical bobbin, 17 magnet, 18 linear motor,
26, 27, 28 Porous material arrangement position.

Claims (5)

[Claims] 1. A casing filled with a working fluid,
A Stirling engine having an expansion space, a compression space, and a bounce space, wherein an oxygen removing material for removing oxygen, a dehumidifying material for removing moisture, and an oxygen moisture removing material for removing oxygen and moisture in the casing. A Stirling institution with at least one of. 2. The oxygen removing material is a porous material containing a deoxidizing agent, and the dehumidifying material is a porous material containing a dehumidifying agent,
The Stirling engine according to claim 1, wherein the oxygen moisture removal material is a porous material containing both an oxygen scavenger and a dehumidifier. 3. The Stirling engine according to claim 1, wherein at least one of the oxygen removing material, the dehumidifying material, and the oxygen moisture removing material is arranged in the bounce space. 4. The Stirling engine according to claim 1, wherein at least one of the oxygen removing material, the dehumidifying material and the oxygen moisture removing material is arranged on the high temperature space side. 5. The at least one of the oxygen removing material, the dehumidifying material, and the oxygen moisture removing material is arranged on the working fluid flow passage between the expansion space and the compression space.
Any of the Stirling institutions listed.