JP2000193332A - Refrigerating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent infiltration of impurity substance such as moisture or the like existing in a drive chamber into a working chamber from the drive chamber being mixed with a working gas in vapor. SOLUTION: This refrigerating system is provided with a working chamber 23, a drive chamber 12 and a rod seal part 8 which prevents the infiltration of a lubricant in the drive chamber 12 into the working chamber 12. A piston or a displacer 6 are reciprocated within an expansion cylinder 2 to generate cold by an expansion process of a working gas in the working chamber 23 formed in the expansion cylinder 2. In this case, the system has cold trap 24 cooled by utilizing cold generated in the working space 23, and a communication means 25 for communication between the cold trap 24 and the drive chamber 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, there has been an urgent need to develop techniques for preserving various samples and various materials at extremely low temperatures in advanced technology fields such as the field of biotechnology and the field of electronic devices. In particular, refrigerating devices such as Stirling refrigerating machines have attracted attention as means for achieving the extremely low temperatures, and are now being widely used for cooling various types of infrared sensors, superconducting devices and the like, and for freezers and freezers for biomedical applications.

Here, the structure of a conventional displacer type Stirling refrigerator will be described with reference to FIG.

The expansion cylinder 2 and the compression cylinder 3 are attached to the main body housing 1 at an angle difference of 90 degrees, and the displacer 6 built in the expansion cylinder 2 and the piston 7 built in the compression cylinder 3 are common. It is connected to the crank mechanism 5 and reciprocally driven in a state where the phases are shifted from each other by 90 degrees.

In the displacer 6, a cold storage material 14 made of, for example, a sintered metal is filled in a cylindrical body 17 having both ends opened, and a working gas flowing from one opening of the cylindrical body 17 is supplied to the cold storage material 14. In the process of passing through the inside and flowing out of the other opening, heat exchange with the cold storage material 14 is performed.

The displacer 6 also has a function as a regenerative heat exchanger, and its heat exchange performance greatly affects the coefficient of performance of a Stirling refrigerator.

The expansion cylinder 2 and the compression cylinder 3 are separated from the crank chamber 12 by oil seals 8 and 9, respectively.
Are communicated with each other by a communication path 4. Oil 10 is injected into the crank chamber 12.

FIG. 3 shows the operation of the Stirling refrigerator with time T on the horizontal axis and stroke S on the vertical axis.

In the Stirling refrigerator, the displacer 6 reciprocates as shown by curves B and C in FIG. 3 and the piston 7 reciprocates as shown by curve D in FIG. Numeral 11 indicates a change in volume in the width region between the straight line A and the curve B in FIG. 3, and the compression space 13 of the compression cylinder 3 changes in volume in a width region between the curves C and D in FIG.

As a result, in the stroke of FIG. 3, the gas in the compression space 13 is compressed as the piston 7 rises, and flows into the expansion cylinder 2 through the communication pipe 4 (ideally, isothermal compression). . This gas passes through the cold storage material 14 in the displacer 6 in the process of FIG. 3 and exchanges heat with the cold storage material 14 to lower the temperature (constant volume cooling). The gas that has passed through the cold storage material 14 flows into the expansion space 11 of the expansion cylinder 2 in the process shown in FIG. 3, and then expands as the piston 7 descends (ideally, isothermal expansion). Next, in the process shown in FIG. 3, as the displacer 6 rises, the expansion space 1
After the gas in 1 passes through the cold storage material 14 and exchanges heat with the cold storage material 14 to increase the temperature, it flows into the compression space 13 again through the communication portion 4 (fixed volume heating).

As a result, the cold head 15 provided at the head of the expansion cylinder 2 is cooled.

[0012]

In the Stirling refrigerator having the above structure, it is not possible to completely remove water and the like mixed during production and assembly. Is most often mixed. For this reason, impurities such as water mixed in the working gas and oil in the crank chamber 12 pass through the oil seals 8 and 9 and enter the space behind the piston 7 or the displacer 6, thereby reducing the efficiency of the apparatus. There was a problem of inviting.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and it is difficult for impurities such as moisture existing in a driving chamber to be mixed with working gas as vapor and to enter the working chamber from the driving chamber. It is an object of the present invention to provide a refrigeration apparatus in which the refrigeration is prevented.

[0014]

According to the present invention, there is provided a working chamber for accommodating a piston or a displacer connected to one end of a rod so as to reciprocate in an expansion cylinder, and the other end of the rod is connected to the working chamber. A drive chamber accommodating a piston drive mechanism for reciprocating the displacer; and a rod seal portion through which the rod penetrates and prevents lubricating oil in the drive chamber from entering the working chamber. Reciprocate in the expansion cylinder,
A refrigerating device that generates cold heat by an expansion process of a working gas inside the working chamber formed in the expansion cylinder, wherein the cold trap is cooled by using cold heat generated inside the working space. And a communication means for communicating the cold trap with the driving chamber.

By using this configuration, impurities such as water vapor mixed in the working gas in the driving chamber are removed by attaching as frost with a cold trap utilizing cold heat generated in the working space. With such a configuration, it is possible to prevent such impurities from entering the working chamber and reducing the efficiency of the apparatus.

More specifically, an opening / closing means provided in the middle of the communication means, and a control means for controlling the opening / closing of the opening / closing means based on the temperature of the cold trap or the operation state of the refrigeration system; May be provided.

By using this configuration, it is possible to prevent the impurity adhering to the cold trap as frost from melting and returning to the driving chamber when the refrigerating apparatus is stopped, in which the temperature of the cold trap rises. Can be.

Further, the cold trap may be arranged so as to be in contact with the outer peripheral side surface of the expansion cylinder. By using this configuration, a cold trap that is cooled by using cold heat from the expansion cylinder can be realized with a simple structure.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those in the above-described conventional example are denoted by the same reference numerals, and detailed description of these portions will be omitted.

FIG. 1 is a schematic sectional view showing the structure of a Stirling refrigerator according to an embodiment of the present invention. In this Stirling refrigerator, an expander 21 that generates cold heat and a compressor 22 that receives and compresses and returns the working gas expanded in the expander 21 are provided in parallel in a vertical direction. In addition, a drive motor 20 as a drive source for driving the displacer 6 and the piston 7 is provided in a crank chamber 12 (drive chamber) including the crank mechanism 5.

The sealing members 8 and 9 as rod seals for partitioning the expansion cylinder 2 and the compression cylinder 3 from the crank chamber 12 extend from the crank chamber 12 to the working space (working chamber) in the expansion cylinder 2 and the compression cylinder 3. A lip-type sealing member is used, which has a higher sealing performance with respect to the flow in the opposite direction than the sealing performance with respect to the reverse flow.

Then, on the outer peripheral side surface of the expansion cylinder 2,
A cold trap 24 is provided in contact with the outer peripheral side surface and is cooled by utilizing cold heat from the expansion cylinder 2.
Are communicated by a communication pipe 25 (communication means).
The cold trap 24 is made of a material having a low thermal conductivity (glass, glass, etc.) disposed so as to contact the outer peripheral side surface of the expansion cylinder 2.
(A stainless steel or the like) 24a and a heat insulating container 24b disposed so as to surround the outer periphery thereof.

As a result, the working gas in the crank chamber 12 which has been heated to a high temperature due to the heat generated by the drive motor 20 moves to the cold trap 24 through the communication pipe 25, and the water vapor mixed in the working gas, etc. Is attached to the surface of the cold trap 24 as frost, and the working gas cooled and cooled to a low temperature in the cold trap 24 moves to the crank chamber 12 through the communication pipe 25. In this way, the working gas naturally circulates between the crank chamber 12 and the cold trap 24,
Impurities such as water vapor mixed in the working gas in the inside are removed by being attached as frost in the cold trap 24 to prevent such impurities from entering the working chamber 23 and reducing the efficiency of the apparatus. Can be.

A control valve as opening / closing means 26 is provided in the middle of the communication pipe 25 near the cold trap 24, and opening / closing is controlled based on a control signal from the control means 27.

The control means 27 controls the driving of the drive motor 20, and while the drive motor 20 is stopped, the control valve 26
Is closed, and after the drive motor 20 is started, the control valve 26 is opened such that the control valve 26 is opened after a predetermined time has elapsed.
Control signal.

This is to prevent the temperature of the cold trap 24 from rising while the drive motor 20 is stopped, and to prevent impurities adhering thereto from melting and returning into the crank chamber 12. Here, the reason why the control valve is opened after the predetermined time has elapsed after the drive motor 20 is started is that the control valve is opened.
This is because the temperature of the cold trap 24 is reduced to a temperature sufficient to cause the impurities to adhere as frost. In the present embodiment, the predetermined time is set so that the control valve 26 is opened after the operation time required to reach −70 degrees or less has elapsed.

In this embodiment, as described above, the case where the opening and closing of the control valve 26 is controlled based on the operating state of the apparatus main body is described. However, the opening and closing of the control valve 26 is controlled based on the temperature of the cold trap 24. Alternatively, the configuration may be adopted. However, in this case, a detecting means for detecting the temperature of the cold trap 24 is separately required.

As described above, a new device is not required as a low-temperature generating mechanism for removing impurities such as moisture vapor by the cold trap 24, and a simple structure is obtained by utilizing the cold heat from the expansion cylinder 2. It can be realized, and the manufacturing cost can be reduced.

The description of the above embodiment is for the purpose of describing the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof.
Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

For example, in the description of the above embodiment, a configuration in which the cold trap 24 is turned rightward with the outer peripheral side surface 2 of the expansion cylinder 2 is described. However, the present invention is not limited to this. For example, copper or the like may be provided between the cold head 15 and the cold trap 24. A configuration may be adopted in which a heat conductive member made of is formed and a part of the extremely low-temperature cold generated in the cold head 15 is thermally conducted to the cold trap 24. In this case, the cold trap 24 can be cooled down to a considerably low temperature, although the generated cooling heat of the apparatus body is slightly lost.

The surface of the low thermal conductivity material 24a of the cold trap 24 may be made uneven. Accordingly, the surface area can be increased, and the amount of impurities that can be attached to the surface of the cold trap 24 can be increased.

[0032]

As described above, according to the present invention, impurities such as water vapor mixed in the working gas in the driving chamber are removed.
Since it is attached and removed as frost by a cold trap using cold generated inside the working space, it is possible to prevent these impurities from entering the working chamber with a simple configuration, and as a result, the efficiency of the device is reduced. Can be prevented.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating a process of a Stirling refrigeration cycle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body housing 2 Expansion cylinder 3 Compression cylinder 5 Crank mechanism (drive mechanism) 6 Displacer 7 Piston 8, 9 Oil seal 12 Crank chamber (drive chamber) 14 Cold storage material 15 Cold head 20 Drive motor 21 Expander 22 Compressor 23 Working chamber 24 cold trap 25 communication pipe (communication means) 26 control valve (opening / closing means) 27 control means

Claims (3)

[Claims] 1. A working chamber for accommodating a piston or displacer connected to one end of a rod so as to reciprocate in an expansion cylinder, and a piston drive mechanism connected to the other end of the rod for reciprocating the piston or displacer. And a rod seal portion that penetrates the rod and prevents lubricating oil in the drive chamber from entering the working chamber, and reciprocates the piston or displacer in an expansion cylinder, A refrigeration apparatus that generates cold heat by an expansion stroke of a working gas inside the working chamber formed in the expansion cylinder, wherein the cold trap is cooled by utilizing cold heat generated inside the working space. A refrigerating apparatus, comprising: a communication means for communicating a cold trap with the driving chamber. 2. An opening / closing means provided in the middle of the communication means, and a control means for controlling the opening / closing of the opening / closing means based on a temperature of the cold trap or an operation state of the refrigerating apparatus. The refrigeration apparatus according to claim 1, wherein 3. The refrigeration system according to claim 1, wherein the cold trap is disposed in contact with an outer peripheral side surface of the expansion cylinder.