JPH04217753A - Stirling freezer - Google Patents

Abstract

PURPOSE:To improve a volumetric efficiency of working gas and improve a freezing capability against an enclosing amount of working gas by a method wherein an independent driving device is operated in response to an actual working gas pressure within a casing and a displacer is directly driven. CONSTITUTION:A displacer 5 is driven by an independent driving device 10 against a driving device 6. This independent driving device 10 is formed by a liner motor and fixed to a casing 1. The casing 1 is provided with a pressure sensor 11 for use in detecting a pressure of working gas. The pressure sensor 11 is connected to a micro-computer 12. The micro-computer 12 sends an output signal to each of driving devices 6 and 10 in response to the content of program and a sensing result of pressure. Each of the driving devices 6 and 10 is fed-back controlled to cause a PV characteristic diagram to be similar to a rational cycle. With such an arrangement, a substantial total volume of enclosed gas can be effectively utilized for compression and expansion, respectively.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Stirling refrigerator in which a piston and a displacer are provided inside a casing so as to be able to reciprocate.

0002

[Prior Art] Japanese Patent Application Laid-Open No. 61-2524 prior to the present invention
In the conventional Stirling refrigerator described in Publication No. 56, a displacer is connected to the piston via an air spring, and the displacer is caused to follow the piston with an arbitrary phase difference, thereby compressing the working gas. It is moved back and forth between the space and the expansion space to obtain extremely low temperatures.

However, in this type of conventional Stirling refrigerator, the phase difference of the displacer with respect to the piston changes arbitrarily and is not maintained in an ideal state. The PV characteristic diagram) is deformed, and only a portion of the working gas can be completely compressed and expanded, resulting in a significant drop in volumetric efficiency.Therefore, there is a drawback that the refrigerating capacity of the Stirling refrigerator is reduced relative to the amount of working gas filled in.

0004

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks, increases the volumetric efficiency of the working gas, and increases the refrigerating capacity of the Stirling refrigerator with respect to the amount of working gas charged therein.

[0005]

[Means for Solving the Problems] The present invention provides a piston and a displacer that are provided inside a casing so as to be able to reciprocate, a compression space and an expansion space are formed inside the casing, and a working gas is sealed therein. The piston is driven by a drive device to reciprocate the working gas between the compression space and the expansion space, and the casing is provided with an independent drive device for driving the displacer and the above. A pressure sensor for detecting the pressure of the working gas is provided, and the displacer is driven based on the detection result of the pressure sensor.

[0006]

[Operation] According to the present invention, by operating the independent drive device based on the actual working gas pressure in the casing to directly drive the displacer, the PV characteristic diagram of the working gas can be changed to the ideal cycle shown in FIG. It is approximated by
Therefore, almost the entire amount of the sealed gas is effectively used for compression and expansion, and therefore the volumetric efficiency of the effective use of the sealed gas of the Stirling refrigerator is increased and the refrigerating capacity is increased.

[0007]

[Embodiment] Next, an embodiment of the present invention will be described.

In FIG. 1, 1 is the casing of the Stirling refrigerator, 2 is the compression space formed inside the casing 1, 3 is the expansion space formed inside the casing 2, and 4 is the side of the compression space 2 inside the casing 1. 5 is a displacer provided on the expansion space 3 side inside the casing 1 so as to be reciprocatable. Reference numeral 6 denotes a drive device for reciprocating the piston 4, which is specifically formed of a linear motor and is attached to the casing 1. 7
is a high-temperature heat exchanger attached to the outside of casing 1,
The heat of compression in the compression space 2 is released. 8 is a communication path that communicates the compression space 2 and the expansion space 3 with each other; 9 is a regenerator installed in the communication path 8;
(not shown). Compression space 2 and expansion space 3
is filled with a working gas consisting of helium, hydrogen, etc. When the working gas reciprocates between the compression space 2 and the expansion space 3, it circulates inside the regenerator 9 and stores heat in the regenerator 9.

The displacer 5 is driven by an independent drive device 10 that is independent of the drive device 6. The independent drive device 10 is formed by a linear motor and is attached to the casing 1. In addition, the casing 1
A pressure sensor 11 is attached to detect the pressure of the working gas. Specifically, the pressure sensor 11 is attached outside the compression space 2 and detects the gas pressure in the compression space 2. Furthermore, the pressure sensor 11 is connected to a microcomputer 12. The microcomputer 12 sends an output signal to each drive device 6, 10 based on the program content and the pressure detection result of the pressure sensor 11, thereby controlling each drive device 6, 10 in feedback mode to control the PV of the Stirling refrigerator. The characteristic diagram is configured to approximate an ideal cycle as described later.

In the Stirling refrigerator, in the compression process, the piston 4 first starts rising from the bottom dead center in response to a start signal from the microcomputer 12, and the working gas releases compression heat from the compression section heat exchanger 7 in an approximately isothermal process. Then, when the pressure in the compression space 2 rises to a predetermined value, the displacer 5 starts descending from the top dead center based on the detection result of the pressure sensor 11, and the high-pressure gas radiates heat while rising inside the regenerator 9 and becomes lower in temperature. and move to the expansion space 3.

In addition, in the Stirling refrigerator, only the displacer 5 continues to descend during the expansion process, so that the working gas expands isothermally, absorbs heat from the surroundings, and cools the low temperature section 13. Next, the displacer 5 reverses and rises, and at the same time the piston 4 starts descending, so that the working gas passes through the regenerator 9 and exchanges heat, and then returns to the compression space 2.

In the Stirling refrigerator, by repeating the cycle consisting of the compression process and the expansion process, the low temperature section 13 is gradually cooled down to 100 to 20K (-17K).
It reaches extremely low temperatures of 3 to 253 degrees Celsius. Furthermore, by directly driving the displacer 5 using the microcomputer 12 and the independent drive device 10 based on the actual pressure in the compression space 2, the PV characteristic diagram of the working gas can be approximated to the ideal cycle shown in FIG. Therefore, almost the entire amount of the sealed gas can be effectively used for compression and expansion, thereby increasing the volumetric efficiency of the effective use of the sealed gas of the Stirling refrigerator and increasing the refrigerating capacity.

[0013]

Effects of the Invention Since the present invention is constructed as described above, the PV characteristic line of the Stirling refrigerator can be changed by controlling the independent drive device based on the actual working gas pressure in the casing and directly driving the displacer. The figure can be approximated to an ideal cycle, and almost all of the sealed gas can be effectively used for compression and expansion, which increases the volumetric efficiency of the effective use of the Stirling refrigerator's sealed gas and increases the refrigerating capacity. I can upload it.

[Brief explanation of the drawing]

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

FIG. 2 is a PV characteristic diagram of a Stirling refrigerator according to an embodiment of the present invention.

FIG. 3 is a PV characteristic diagram of a conventional Stirling refrigerator.

[Explanation of symbols]

1 Casing 2 Compressed space 3 Expansion space 4 Piston 5 Displacer 6 Drive device 10 Independent drive device 11 Pressure sensor

Claims (1)

[Claims] 1. A piston and a displacer are each provided inside a casing so as to be able to reciprocate, a compression space and an expansion space are formed inside the casing and a working gas is sealed therein, and the piston is driven by a drive device. The working gas is moved back and forth between the compression space and the expansion space, and the casing includes an independent drive device for driving the displacer and a pressure for detecting the pressure of the working gas. A Stirling refrigerator comprising: a sensor; and the displacer is driven based on the detection result of the pressure sensor.