JPH05141797A - Pulse tube type refrigerating machine - Google Patents

Abstract

PURPOSE:To permit the practical use of the above machine by improving the efficiency and the structure of the pulse tube type refrigerating machine, which is developed instead of a thermal engine or especially a refrigerating machine applying Stirling cycle. CONSTITUTION:Horizontally opposed compression pistons 4, 4' are arranged in a crankcase to constitute four sets of compression spaces 6, 6, 6', 6'. An expansion piston 9, having a phase angle (preferably 20 deg.) is arranged with respect to both of the compression pistons 4, 4' while the structure of all these constitutions is received in the crankcase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse tube refrigerator which uses a pulse tube and does not require an expansion piston which reciprocates at a low temperature.

[0002]

A Stirling cycle consisting of two isothermal processes and an isochoric process is a working fluid (helium, argon,
It is a closed cycle device using hydrogen etc., and is developed as an external combustion engine or a refrigerator. In a refrigerator using this Stirling cycle, mechanical vibration generated by the reciprocating movement of a long expansion piston having a low temperature is transmitted to the cold head, causing noise in a sensor and the like.
Further, the contact between the outer peripheral surface of the long expansion piston and the inner peripheral surface of the cylinder causes abrasion powder to contaminate the working fluid and the regenerator. This causes deterioration of the performance of the refrigerator and failure.

In order to solve the above-mentioned drawbacks of the refrigerator applying the Stirling cycle, a pulse tube refrigerator (Tatsuo Inoue, Low Temperature Engineering Vol. 26 No.
2 (1991)) was proposed. In this method, a radiator, a regenerator (regenerator), a cold head, and a pulse tube orifice are connected in series between the compression space and the buffer tank, and a working gas such as helium is used as a medium to generate a low temperature. There is.

The structural feature of this pulse tube refrigerator is to use a cylindrical pulse tube made of metal, ceramic, or a composite material thereof. This pulse tube keeps a considerably large temperature gradient during the operation of the refrigerator and plays a heat insulating effect. However, as is known, the refrigerator using the pulse tube is not always efficient.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses a combination of a pulse tube and an expansion piston at room temperature, instead of the pulse tube, orifice and buffer tank that have been conventionally used. Basically used.

According to the present invention, specifically, the compression space,
In a pulse tube refrigerator in which a plurality of low temperature generation systems having a radiator, a regenerator, a cold head, a pulse tube and an expansion space are connected in a heat exchange relationship, four pairs are provided by a pair of horizontally opposed compression pistons. Of the four compression spaces, the expansion pistons are connected to the crankshaft for operating both compression pistons with a phase angle, and a pair of expansion spaces are formed by the expansion pistons. Provided is a pulse tube refrigerator that communicates with each other.

[0008]

[Function] Since two sets of each of the four sets of compression spaces are connected, a large compression space can be secured, and the volume of the expansion space can be easily set within the range of 6.6 to 30% of the volume of the compression space. You can

[0009]

EXAMPLE Referring to FIG. The pulse tube refrigerator 1 has a compression space 6 defined in a cylinder 5 by a compression piston 4 that reciprocates by a rod 3 connected to a crankshaft 2. Further, another rod 7 connected to the crankshaft 2 reciprocates the expansion piston 9 in the cylinder 8 to make the volume of the expansion space 10 variable.

The expansion space 10 is kept at room temperature, and the crank angles of both rods 3 and 7 are such that the expansion space 10 is compressed space 6.
On the other hand, it is selected so as to proceed with a certain phase difference within the range of 10 to 45 degrees. Preferably, the phase difference is 20 to 30.
Degree.

The compression space 6 includes a radiator 11, a regenerator 12,
It communicates with the expansion space 10 via the cold head 13 and the pulse tube 14. The regenerator 10 is filled with a regenerator material such as a stainless steel or bronze mesh, a lead group of small balls, and strange earth. The portion configured in this way is referred to as a first heat system.

A second heat system is formed by being juxtaposed with the first heat system. Parts in the second heat system that are the same as those in the first heat system are given a dash and their explanation is omitted. As is apparent from FIG. 1, the regenerator of the second heat system is different from the first heat system in that it comprises two parts 12'-1 and 12'-2.

The first heat system and the second heat system are a cold head 13 of the first heat system and both regenerators 12 'of the second heat system.
The parts between -1, 12'-2 and the parts between -1, 12'-2 are connected in a heat exchange 15 relationship. Such a coupling transfers the low temperature of the cold head 13 of the first thermal system to the working fluid of the second thermal system, and enables the cryogenic temperature to be generated in the second thermal system.

The example of FIG. 2 will be described. The same parts as those in the example shown in FIG. In contrast to FIG. 2 and FIG. 1, in the example of FIG.
In addition to the arrangement of 4'and the expansion pistons 9 and 9'side by side, the pulse tubes 14 and 14 'of both heat systems are arranged concentrically. It differs from the example of FIG. However, the basic operation is the same between FIG. 1 and FIG.

FIG. 3 shows an arrangement example of each element in the example of FIG. Regenerator 12 'centered on the second heat system pulse tube 14'
-1, 12'-2, the regenerator 12 and the pulse tube 14 are put together in a cylindrical shape in a substantially concentric relationship. As a result, both heat systems can be made compact.

FIG. 4 shows an arrangement example of each element of the example of FIG. Also in this example, the regenerators 12'-1, 12'-2, the pulse tube 14, and the regenerator 12 are arranged in a cylindrical shape concentrically around the pulse tube 14 '. A heat exchange 15 is performed between the cold head 13 of the first heat system and the regenerators 12'-1 and 12'-2 of the second heat system. This configuration is effective in compacting both heat systems.

3 and 4 show examples of preferable specific arrangements of the regenerator and the pulse tube, FIGS. 5 and 6 show specific configurations around the crankshaft 2. As shown in FIG. The two double-acting pistons 4 and 4'are horizontally opposed to each other, and the four compression spaces 6 and
6, 6 ', 6'are configured to make one of the compression spaces 6, 6 operating in the same phase conductive and the other compression space 6', 6'conductive.

The expansion pistons 9 have the same crankcase 1
It is housed in 6 and constitutes two expansion spaces 10, 10 '. The crank angles of both rods 3, 3 ', 6 are within the range of 10 to 45 degrees. As is clear from FIG. 5 and FIG. 6, both pistons 6, 6 ′, 9, 9 ′ and rods 3, 3 ′, 7 can be housed in the crankcase 16, and the flexible structure is connected to the compression space and the expansion space. A compact refrigerator can be constructed by connecting the tubes to the regenerator and pulse tube shown in FIGS. 3 and 4.

The compression pistons 4 and 4'and the expansion pistons 9 and 9'have the same or different phase angles, and
The volume of each compression space and each expansion space may be made variable so as to obtain the low temperature expected in the cold head. This change is possible by selecting the angle of the crank portion with respect to the crankshaft.

In the examples shown in FIGS. 7 and 8, linear pistons 17 and 18 are used instead of the crankshaft 2 to reciprocate both pistons 4 and 9. Expansion piston 9
Controls the energization of both linear motors 17 and 18 so that the compression piston 4 advances at a phase angle of 10 to 45 degrees. A buffer tank 19 is provided at a portion opposite to the compression space 6 via the compression piston 4. Compression space 16
The buffer tank 19 and the buffer tank 19 are connected by a flexible pipe having a control valve 20 and a filter 21. The control valve 20 and the filter 21 serve to remove impurities in the working fluid, improve the purity of the working fluid, and control the pressure of the working fluid.

In the example shown in FIG. 8, the second buffer tank 22 is constructed by using the convex piston 9a as the expansion piston. The movement of both pistons 4, 9, 9a can be regulated by a position sensor. By arranging the examples shown in FIG. 7 or FIG. 8 in parallel, but by making the cold heads 13 in common (for example, by arranging several cold heads 13 in a concentric cylindrical shape), the same cold temperature can be applied to one large cold head. May be generated. Alternatively, as shown in FIGS. 1 and 2, the cold head 13 may be used as pre-cooling for another low temperature generation system, and heat may be exchanged with another low temperature generation system in this portion.

In any of the examples, the volume of the expansion space is preferably in the range of 6.6-30% of the volume of the compression space.
The required volume of compression space may be ensured by several compression pistons.

The example shown in FIGS. 7 and 8 is a linear motor 1
Both pistons 4 and 9 are operated by using 7 and 18, but as shown in FIG. 9, instead of the linear motors 17 and 18, the crankshaft 2 and the electric motor M are used and both pistons 4 and 9 are used. May be reciprocated.

In the example shown in FIG. 10, when the expansion work of the expansion space 10 becomes large, the temperature of the expansion space becomes lower than room temperature (for example, the freezing temperature is 80K and the expansion work is 50%).
Above W, if the heat dissipation effect is not sufficient, the temperature of the expansion space will drop to about 250K), which is effective in preventing this. The heat from the compression space 6 is transferred to the working fluid in the expansion space 10 by using the radiator 23 to prevent the temperature of the expansion space 10 from decreasing. The reference numerals in FIG. 10 indicate the same parts as those used in other examples.

To supply a high-purity working fluid to the compression space 6, a filter 21 may be arranged between the pressurizing valve 24 and the pressure reducing valve 25. As a result, the working fluid from the crankcase is supplied as high-purity working fluid to the compression space 6 via the filter 21 and the pressure control valve 20.

Referring to FIG. In the example shown in FIG. 1, when the refrigeration temperature TE is kept constant at 80K and the crank angle is increased from 0 degree to 30 degrees, the coefficient of performance (ratio of refrigeration output to consumed power) is 0.01 to 0. Rise to .027. At 40K, the maximum coefficient of performance is when the crank angle is 22 degrees. As is clear from FIG. 11, there is an optimum crank angle according to the freezing temperature, but the value is within the range of 20 to 30 degrees.

[0027]

[Effect] According to the present invention, since a low-temperature moving part is not required, that is, the expansion piston can be placed at room temperature, manufacturing and maintenance can be facilitated, and a plurality of cycles can be obtained, so that it can be used in a plurality of cycles. Refrigeration output can be adjusted. The practical refrigeration capacity is improved compared to the conventional one.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of the present invention.

FIG. 2 is an explanatory diagram of another example of the present invention.

FIG. 3 is a cross-sectional view showing a specific configuration of an example of the present invention.

FIG. 4 is a sectional view showing a specific configuration of another example of the present invention.

FIG. 5 is a vertical sectional view of a crankshaft portion.

FIG. 6 is a cross-sectional view of a crankshaft portion.

FIG. 7 is a sectional view of an example using a linear motor.

FIG. 8 is a sectional view of another example using a linear motor.

9 is a plan view of an example in which a crankshaft is applied to the example of FIG.

FIG. 10 is an explanatory diagram showing another example of the present invention.

FIG. 11 is a graph showing the relationship between crank angle and coefficient of performance.

[Explanation of symbols]

 2 crankshaft 3,3 ', 7,7' rod 4,4 'compression piston 6,6' compression space 9,9 'expansion piston 10,10' expansion space 12,12 'regenerator 13,13' cold head 14 , 14 'Pulse tube 17,18 Linear motor 19,20 Puffer tank

Claims (2)

[Claims] 1. A pulse tube type refrigerator in which a plurality of low temperature generation systems having a compression space, a radiator, a regenerator, a cold head, a pulse tube and an expansion space are connected in a heat exchange relationship and arranged in a horizontally opposed type. 4 sets of compression spaces are formed by the paired compression pistons, the expansion pistons are connected to the crankshaft for operating both compression pistons with a phase angle, and the pair of expansion spaces are formed by the expansion pistons. A pulse tube refrigerator that connects the compression spaces that operate in the same phase. 2. The pulse tube refrigerator according to claim 1, wherein the crank angle of the expansion piston is advanced by 90 degrees with respect to the compression piston.