JPH05118685A - Pulse tube type stirling refrigerator - Google Patents

Abstract

PURPOSE:To restrain mechanical vibration and improve the efficiency and the reliability of the subject machine by a method wherein a radiator, a cold heat accumulator, a cold head and a pulse tube are arranged sequentially between the compression space of a large capacity and a small capacity expansion space, reciprocating a crank for compression by an expansion crank advanced by a predetermined phase angle. CONSTITUTION:A compression piston 16 is connected to a crankshaft 14 through a connecting rod 15 while a compression space 18 is formed of the top of the piston 16 and a cylinder 17. An expansion piston 24 is connected to the same crankshaft 14 through another connecting rod 25 with the advanced phase difference within the range of 5-45 deg. than the variable volume of the compression space 8 while an expansion space 26, having a capacity smaller than the compression space, is formed by another piston 24 and an expansion cylinder 23. A radiator 20, a cold heat accumulator 22, a cold head 27 and a pulse tube 21 are connected and arranged sequentially between the compression space 18 and the expansion space 26. According to this constitution, a displacer or an expansion piston, which is necessitated so far, becomes unnecessary and the improvement of efficiency as well as reliability can be contrived.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse tube type Stirling refrigerator in which a Stirling cycle refrigerator and a pulse tube used in the heat insulation process of the pulse tube refrigerator are skillfully combined.

[0002]

2. Description of the Related Art As known in the art, the Stirling cycle is theoretically an ideal cycle consisting of two isothermal processes, and in a working refrigerator, a working fluid (helium, neon, argon, nitrogen) is used. , Hydrogen, air, etc.
Alternatively, it is a cycle engine for a closed cycle that uses helium or hydrogen as a mixed gas, hereinafter referred to as a fluid). In operation as a refrigerator, it is known that it has higher efficiency than any other refrigeration cycle and is used as an evaporator and a low temperature prime mover for liquefied natural gas.

The structure of the Kinematic Stirling cycle is shown in FIG. 8, and the P-V diagram and the T-S diagram are shown in FIGS. 9 and 10. In FIG. 8, a compression piston 3 connected to a crown shaft 2 driven by a prime mover (not shown) and reciprocally moved by a connecting rod 11.
And the compression cylinder 1 having a variable volume, and the phase difference of the variable volume is within the range of 70 degrees to 110 degrees (the optimum phase difference is about 90 degrees and 60 degrees when the freezing temperature becomes low). The radiator 5, the regenerator 6, and the cold head 7 are connected between the expansion piston 9 and the expansion space 10 constituted by the expansion cylinder 8 which are operated while maintaining a constant phase angle difference of (approaching). There is.

Logically, the operating principle is that the fluid in the compression space 1 is isothermally compressed while radiating heat by the radiator 5 (isothermal compression process in FIG. 9, a → b1). Next, the fluid is stored in the regenerator 6 by the regenerator 6 because the compression piston 3 moves toward the top dead center.
It is cooled to about 0K (about 243 degrees C) and enters the cold head 7 and the expansion space 10 with a constant volume (the isochoric process in FIG. 9, b1 → a). Next, this fluid pushes the expansion piston 9, and the expansion work is recovered as power by the crank 2 via the connecting rod 12 (heat is generated from the uncooled object by the cold head 7 in the isothermal expansion process of FIG. 9). Swelling while absorbing, c → b1). Finally, the fluid in the expansion space 10 that has performed the expansion work and becomes the maximum is pushed out because the expansion piston 9 goes from the bottom dead center to the top dead center, and returns to the expansion space 1 from the regenerator 6 and the radiator 7 (Fig. The isovolume process of 9, d1 → a), one cycle ends. Various refrigerators that revert to this Stirling cycle are often used especially for medium and very low temperatures.

Further, a pulse tube type refrigerator having a fundamentally different type is described in W. 1963. E. First proposed by Gifford et al. This low-temperature generation method has high expectations for the practical application of a highly reliable refrigerator due to the fact that there is no mechanical vibration in the cold head because there are no moving parts in the low-temperature part and the simple equipment configuration. Although the explanation of the operating principle is omitted here, in the equipment configuration of the cycle, the simple shape pulse tube which is a hollow cylindrical tube of metal or composite material is the main component and is responsible for the adiabatic process. it is obvious. It is considered that in the cycle operation, the working fluid is generated at a low temperature due to the phase shift of the pressure change in the pulse tube during the movement between the compression space and the buffer tank. The advantage of this method is that it does not require an expansion piston that reciprocates at low temperatures.

[0006]

The Stirling refrigerator and the pulse tube refrigerator as described above have been used many times by making the best use of their respective characteristics, but at the same time, there was a problem to be solved. That is, the disadvantage of this Stirling refrigerator (similar to the prime mover) is that the relatively long expansion piston 9 (for example, the refrigerator output is 80K and the refrigerator output is 200K).
In the case of about W, a reciprocating motion including a guide piston (not shown) of 35 to 45 cm) causes contact and resonance with the expansion cylinder 8 to generate mechanical vibration, which is transmitted to the cold head 7 nearby. , It has a bad effect on the object to be cooled by the cold head. For example, vibration was transmitted to the electronic sensor, causing noise. There is also a displacer type Stirling engine in which the expansion piston 9 is unworked to reduce mechanical vibration, but even if a relatively long displacer with extremely low temperature is mechanically manufactured with high accuracy, it will be affected by large temperature changes. The dimensional accuracy was wrong, and a contact accident during reciprocating motion was frequently caused.

As a result, mechanical vibration is generated, and dust and their decomposed gas are generated due to contact wear of the displacer, contaminating the fluid and causing performance deterioration. Furthermore,
A mixed fluid of dust and impure gas was clogged in the regenerator 6 composed of a myriad of small spheres and regenerator material of wire mesh (condensation / solidification by decomposition product gas having a high boiling point), causing a blockage accident. Also,
The manufacturing costs of the expansion piston and displacer, which require high processing accuracy, the inner surface finishing of these cylinders, and the drive mechanism were very high. As a result, the use of long expansion pistons and displacers has led to a reduction in reliability as a Stirling engine.

On the other hand, in the pulse-tube refrigerator, the process of low-temperature generation uses the characteristics of the non-equilibrium state of the working fluid as the operating principle, so that analysis as a cycle is difficult. In addition, although papers have been published from the viewpoint of thermoacoustics and others, there are many approximations to the conditions in each case, and the operating principle cannot be said to be logically established. It has been demonstrated that low temperature production is possible, but in practice its efficiency was rather low.

[0009]

SUMMARY OF THE INVENTION The present invention introduces a pulse tube used in the heat insulation process of a pulse tube type refrigerator in order to solve the above-mentioned drawbacks into a Stirling cycle equipment structure, and the Stirling cycle refrigeration is carried out. It has a simple structure that does not require any expansion piston or displacer that reciprocates at low temperature, which was indispensable for the machine, has no mechanical vibration in the cold head, and is highly efficient and highly reliable. The present invention is intended to provide an improved Stirling refrigerator using a pulse tube, which enables to provide at low cost.

That is, the present invention has, as its constitution, a compression space having a relatively large capacity, which is constituted by the top of at least one compression piston reciprocating by a compression crank driven by external power and a compression cylinder, Phase angle α advanced by 5 ° to 45 ° from the compression crank
Has an expansion space having a relatively small capacity formed at the top of an expansion piston that reciprocates by an expansion crank that is interlocked with a radiator, a regenerator, and a cold head between the compression space and the expansion space. And a pulse tube type Stirling refrigerator in which pulse tubes are sequentially arranged.

The compression space may be formed by a plurality of compression spaces formed by the tops of a plurality of compression pistons, or in a convex cylinder having a cold head having two or more stages. , A cylindrical pulse tube of which a part is at least doubled is disposed around the axis, and a regenerator or a regenerator and a radiator are further disposed on the outer peripheral portion of the cylindrical pulse tube to dissipate the heat. Integrating the configurations of the heat exchanger, the regenerator, the cold bed and the pulse tube, and connecting the compression space and the expansion space with the integrated radiator, regenerator, cold bed and the pulse tube by flexible piping. It is something to be solved.

Further, the phase angle α is 20 ° to 25 ° and 50K in the required freezing temperature range of 30K to 50K.
It is characterized in that it is 25 ° to 40 ° in the region of up to 120K, and the volume ratio of the compression space and the expansion space (compression space volume / expansion space volume) is 5 to 20 and preferably 10 to 20. The pulse tube type Stirling refrigerator is intended to solve the problem.

[0013]

FIG. 1 is a schematic view of a flow path and a sectional structure of a pulse tube refrigerator according to the present invention for the purpose of simplifying the equipment structure. The thermodynamic operation process theoretically involves two adiabatic processes (a-, as shown in the TS diagram of FIG. 10).
b, cd) and two equal volume processes (bc, da) are pseudo Stirling cycle heat engines. In actual operation, it becomes as (a-bx, c-dx) with an irreversible process.

A major feature of the present invention is that the existing Pierce Stirling refrigerator of FIG. 8 has the expansion piston 9 and the expansion cylinder 8 reciprocating at an extremely low temperature removed, and a pulse tube refrigerator has an adiabatic process as an alternative. It is assumed that the pulse tube 21 is assumed to exist in the cycle, and the adiabatic expansion process operates as a gas piston instead of the solid piston of Stirling by the synergistic function of the expansion space 26 and the pulse tube 21 by the expansion piston 24 at room temperature. There is something to do. As a result, there is no expansion piston 9 or expansion cylinder 8 or any other device that reciprocates due to the low temperature, which requires a long distance for heat insulation and the expansion space 10 that becomes a cryogenic temperature in FIG. , All the drawbacks of the previous Stirling refrigerator were eliminated.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an embodiment of the present invention, which is formed by a compression piston 16 and a cylinder 17 which are mechanically reciprocated via a connecting rod 15 by the rotation of a crankshaft 14 driven by an electric motor (not shown). Fluid (the same gas as Stirling) compression space 18 (also referred to as compression space portion because the compressor does not have a discharge valve and a suction valve).
Is not limited to the piston / cylinder including the expansion space 26, but may be formed by a diaphragm, a bellows, or the like) via the cone rod 25 on the crankshaft 14 and within a range of 5 to 45 degrees from the volume change of the compression space 18. (The optimum phase difference is approximately 20 degrees) The phase difference is advanced (varies slightly depending on the operating condition, and the volume of the expansion space is operated while being variable while maintaining a constant phase difference advanced from the compression space). Therefore, a pipe 19, a radiator 20, a stainless steel or a bronze mesh, is provided between the expansion cylinder 23 at normal temperature which is maintained and held and the expansion space 26 formed by the expansion piston 24. A regenerator 22 filled with regenerator material such as lead or strange earth of innumerable small balls, a cold head 27 that cools an object to be cooled and generates freezing, a pulse tube 21 and a pipe 2. It is connected via a.

Alternatively, as shown in FIG. 2, the pulse tube 21 and the expansion space 26 are connected via a heat exchanger 29 manufactured integrally with the radiator 20 of FIG. 1 and cooled by air or liquid by a cooling fluid 30. To be cooled. This heat exchanger 29 prevents the temperature of the fluid from dropping below the expansion space 26 at room temperature due to the irreversibility generated during the adiabatic expansion process, and at the same time, recovers the cold heat and the heat radiation load of the heat radiator 120 in FIG. Has the effect of lowering. Although not shown, the distance between the expansion space 26 and the compression space 18 is short because they are formed by the same crankcase, and if the pipes 19 and 28 are concentric double pipes,
The heat can be exchanged with each other to obtain the same effect as that of the radiator 29, and the piping system can be simplified by apparently using one pipe.

Further, the operation in the ideal operating state will be described with reference to the TS diagram of FIGS. 1 and 10 and the PV diagram of FIG. The fluid in the compression space 18 is isentropically compressed from the point a at room temperature (adiabatic compression process) to a point b of higher temperature and pressure, and then radiates heat to the b1 in the process of constant volume in the heat exchanger 20, From b1, it enters the regenerator 22 and is cooled to point c (the isochoric process). Next, when the expansion piston 24 moves toward the bottom dead center, the fluid in the cold head 27 and the pulse tube 21 enters the expansion space 26, pushes the piston 24, expands the work of rotating the crankshaft 14, and reaches the point d (heat insulation). The expansion process maximizes the volume of 26). Further, the fluid in the expansion space 26 is isometrically cooled through a pipe 28 together with the fluid in the pulse pipe 21 by a cold head 27 to cool an object to be cooled (d-d1), and from d1 to a regenerator 22 and a radiator 20. It enters and is warmed up to point a and returns to the compression space 18 (equal volume process) to complete one cycle. In the actual operation process, it becomes like a chain line (a-bx, c-dx) with an irreversible process. It should be noted that these processes are polytropic processes with inefficiency during actual operation, and if a PV diagram is drawn, the sharp corners in each process will be shaved and smoothed.

FIG. 4 compares the curve (a) of the relationship between the phase difference (α) and the minimum reached temperature (Tmin) obtained by the experiment of the refrigerator of the present invention with the case of the Stirling cycle refrigerator (b) of Slit. To do. In the present invention, the optimum phase difference (OPT) varies depending on the freezing temperature, the specifications of the equipment, the volume ratio, and the operating conditions.
Maximum efficiency is achieved at 20 degrees using only a bronze wire mesh as the regenerator. That is, when the required freezing temperature is in the range of 30K to 50K, the OPT line between the curves 1 and 2 is 20 degrees to 25 degrees.
The maximum refrigeration output can be obtained by operating within the range of the phase difference between the degrees. This means that a sufficient refrigerating output can be obtained within a curve in the range of plus 25 degrees and minus 15 degrees around this 20 degree.

It means that Tmin obtained as the distance from 20 degrees approaches 60 degrees and gradually increases, and both the efficiency and the refrigerating output decrease. When the curve is 0 degrees or less than 20 degrees, that is, the curve to the same phase is an acute angle and becomes -15 degrees or less than 0 degree, Tmin sharply increases to 1 although not shown.
Rise above 00K. In the present invention, below 0 ° is the limit of minus 5 °, and below this means that a sufficient refrigerating output cannot be obtained. It has been experimentally confirmed that 20 ° to 40 ° is preferable in the region of 50K to 120K.

That is, the optimum phase difference (OPT) becomes higher as the required freezing temperature becomes higher, for example, 70 to 9
When a freezing temperature of 0K is required
It is about 36 degrees from the PT line. That is, the maximum refrigeration output is obtained at this phase angle, and the optimum volume ratio (volume of compression space / volume of expansion space) is also reduced. Control of the phase difference is
In the actual operation of the refrigerator, it is possible to freely change the optimum phase difference by an AC servomotor or the like depending on the required refrigeration temperature, but this is expensive and complicated. Therefore, it is operated with a fixed phase difference except for specific applications.

In FIG. 4, the Stirling (b)
In the case of, Tmin is 25 K, which is lower than that of the refrigerator of the present invention. The optimum phase angle is approximately 90 degrees, and the refrigerating output can be obtained within a gentle curve within the range of ± 30 degrees (60 degrees to 120 degrees) centered on this. However, it means that the efficiency is high within the range of 90 ° ± 10 °, although it depends on the operating conditions. It is well known that this α is the same in the Stirling motor, and the maximum efficiency is obtained at about 90 degrees. As described above, the present invention is based on α and Tm
From the in relation, the thermodynamic difference from the existing Stirling engine is clear.

The pulse tube 21 may be a composite material or a ceramic material, but it is mainly a hollow cylindrical tube made of stainless steel or the like having poor heat conduction, and when the refrigerating output is 77 K and 100 W, the length is 25 to 32 cm and the inner diameter is. 2cm ± 0.5cm, wall thickness 0.1
Although not shown, a rectifier for fluid, which is made of mesh or the like, may be attached to the entrance / exit inside, although not shown. The rectifier on the expansion space 26 side may be made integrally with the heat exchanger 29.

The volume ratio of the compression space 18 and the expansion space 26 (volume of compression space / volume of expansion space) can efficiently generate a low temperature within a range of 5 to 20 depending on the freezing temperature, and the required freezing temperature. The lower is, the closer to 20, the smaller the optimum phase is. The optimum volume ratio is cold head 2
7, the freezing temperature and the output, the operating conditions such as the average operating pressure of the fluid, the rotation speed, and the phase difference, and the length of the pipe (dead volume and pressure loss in the pipe). The volume ratio is 5 to 10 when the freezing temperature is 150K to 77K, and 10 when the freezing temperature is 77K to 10K.
Even if the volume ratio is 20 or less, low temperature generation is possible, but in this case, the coefficient of performance is significantly reduced.

FIG. 3 shows an embodiment in the case of a water condenser of a turbo molecular pump. The cold head 27 is made of a fin tube and placed in the vacuum of the suction port of the turbo pump, and the pulse tube 21 is bronze or the like. The cold head 2 is arranged at the axial center of the regenerator 31 made of stainless wire mesh.
The fluid that has entered the pulse tube 21 from 7 passes through the pipe 28 from the pulse tube that has been partially cooled by the radiator 29, and the expansion space 26
Connected to. In the pulse tube, when the refrigerating output is large or the rotation speed of the piston is high (18 Hz or more), a plurality of pulse tubes may be used in parallel with the regenerator. The shape of the pulse tube is not limited to a cylinder, and it can be an elliptical shape, a square shape, or a conical shape. However, if the pressure of the fluid is high, the thickness of the cylindrical shape can be made thin, and the heat loss rate due to this can be reduced There is an advantage.

6A and 6B show the specifications when the refrigerating output is 100 K and 30 W when the crankcase type is used to form the compression and expansion spaces in FIGS. 6A and 6B. Pulse tube: stainless steel 1.6 cmφ, length 25 cm, regenerator: stainless steel 150 mesh 2.5 cmφ, 800
The volume of one sheet, the compression space: 500 cc. Expansion space volume: 4
0 cc. Rotation speed: 300 rpm (5 Hz). Working average pressure (He): 14 atm. Phase difference: 35 degrees. Minimum reached temperature: 40K. Input: 0.75 Kw. Performance index: 750/30 = 25 under these conditions. Performance coefficient: 1/25 =
0.04. Input: 0.75KW. Under these conditions, performance index: 750/30 = 25, performance coefficient: 1/25 =
0.04, efficiency is expressed by% Carnot value, η% = (30
0-100) / 100/25 * 100% = 8%,
It is a value close to that of a commercially available Gifode McMahon cycle refrigerator with the same output.

It is clear that the efficiency of the refrigerator of the present invention is high even at the early stage of development. In order to completely prevent mechanical vibrations from the mechanical parts of the expansion space 26 and the compression space 18, the cold head 27 uses the flexible pipes of 1 to 2 m as the normal temperature pipes 32-1 to 32-4 shown in FIG. Can be However, as the distance of the flexible pipe increases, the dead volume in the pipe 32 and the pressure loss due to the length increase, and the compression ratio of the fluid in the compression space 18 decreases,
The refrigeration output decreases as the length of the pipe increases. With the specifications of the refrigerator described above, there is a decrease of about 12% at a length of 1 m. That is, the shorter the length, the better the efficiency.

However, the present invention does not require a moving mechanism such as a low-temperature piston to provide mechanical vibration of several μ to several tens of μ in the cold head in any other cycle refrigerator. It can be completely removed by using a tube. 33 is a piston ring, 2
1, 22, 27 are insulated by vacuum. Further, when the required freezing temperature is lower than 30 K, it can be easily obtained by filling the regenerator 22 with innumerable lead globules or strange earth regenerator material and increasing the compression ratio.

An embodiment of the cryopump of the present invention will be described below with reference to FIGS. 5, 6 (A), 6 (B) and 7. In the figure, the fluid in the compression space 37 is compressed by the motor 51 through the planetary gear 50, the crankshaft 34, the connecting rod 35, and the guide piston 56, and is compressed by the vertically reciprocating compression piston 36.
From the 7-1, the pipe 37-2, the radiator connection port 48, and the cooling fluid 54 are cooled to participate in the temperature generation from the room temperature to about 77K from the radiator 38 at a room temperature that cools a part of the pulse tube 44. Enter the regenerator 39. Further regenerator entrance 3
A part of the fluid from 9-1 cools the flange type cold head lower end portion 42 from the inlet / outlet port 42-1 and the compression space 3 from the concentric cylindrical pulse tube 44, the inlet / outlet port 45-1, and the pipe 45.
From the volume change of No. 7, the expansion space 46 in which the volume is changed by advancing with a constant phase difference within the range of 5 to 45 degrees enters from the inlet / outlet port of 46-1. Note that θ in FIG. 5 is a bank angle between the compression piston 36 and the expansion piston 49 arranged vertically, and this angle corresponds to the phase difference α and is fixed as shown in FIG. 6B.

On the other hand, the remaining fluid at the inlet / outlet 42-1 is
Cooling the cold head upper end 41 which produces 20K or less with a flange type from the cold accumulator 40-1 of the cold accumulator 40 filled with stainless wire mesh, innumerable lead balls, and regenerator materials such as rare earths, and the pulse at the axis center of the cold accumulator 40 Enter the tube 43, 43-1 to 2
The heavy pulse tube 45-1 merges with the fluid from the cold head lower end portion 42 described above, and the expansion space 4 is expanded from the piping 45.
Enter 6. This low temperature generation method has been described in FIG.

The connecting rod 47 and the crankcase 5
2, a pressure resistant cover 53, an oil pump 57, and a vacuum flange 55. FIG. 7 shows a cold head pulse tube of the present invention,
It is a partial schematic diagram of one Example which made a regenerator compact. That is, in this embodiment, the pulse tube 43 that generates the lowest temperature is arranged at the center of the cold heads 41 and 42 that generate two temperatures, and then the pulse tube 44 and the regenerator 39 are formed on concentric cylinders. Because it did, it became compact,
The high-pressure and low-pressure valves used in ordinary cryopumps made it easy to replace the cold head with mechanical vibration of the Gifode McMahon refrigerator.

The number of cold heads can be increased to two or more by further increasing the number of pulse tubes and regenerators, and a lower temperature can be easily obtained. See also FIG.
The structure for forming the compression space and the expansion space in FIGS. 6A and 6B can be set at the lowest price by giving a phase difference by the bank angle. Further, since the volume of the compression space becomes ten times more than that of the expansion space even when 77K is generated, if this is divided into two parts and formed by driving the horizontally opposed piston, the vibration is reduced and the structure becomes compact. The expansion space at this time may be formed by an expansion piston vertically arranged and vertically moved.

[0032]

The effects of the present invention are listed below in comparison with Stirling and other refrigerators. B) A relatively high efficiency can be obtained without using a displacer or an expansion piston that reciprocates at a relatively long low temperature. B) Since there is no low-temperature moving part or this drive mechanism, dust is not generated due to contact between the piston and cylinder. Therefore, the working fluid is not contaminated, the performance is stable for a long time, and the reliability is greatly improved due to the reduction of mechanical parts. C) The expansion and compression pistons reciprocate only at room temperature, and there is almost no vibration in the cold head compared to existing engines. For this reason, the noise due to the mechanical vibration that has been applied to the object to be cooled is completely removed, and the expectation of application to electronic systems in particular has increased. D) The simplification of the refrigerator structure has raised expectations for improved reliability in system applications. (E) Since the present invention does not require a low-temperature moving part, it can be easily manufactured by the existing technique as in a fluid machine at room temperature. F) The equipment structure is simple, and since the number of parts has decreased and the parts and mechanisms that require precision processing have disappeared, the manufacturing price has dropped significantly, and highly reliable refrigerators and prime movers can be provided at low cost. G) Since the relatively long expansion piston and displacer, which are expensive and expensive to manufacture and which are easy to break, have been eliminated, handling is easy as the device moves. Also, the driving operation has become easier as well.

The volume of the compression space 13 is equal to that of the expansion space 26.
Since it is much larger than that of the Stirling engine, the volume 13 of the compression space is divided into two, and two compression pistons that form the compression space are arranged horizontally opposed to each other and driven. By doing so, since the volume changes of the two compression spaces are performed in the same phase, the vibration of the compression part at room temperature can be further reduced due to good mechanical dynamic balance. Also,
If the device configuration of the present invention is manufactured by combining a plurality of sets,
The efficiency can be further improved with the low vibration.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of the present invention.

FIG. 2 is a schematic view of another embodiment of the present invention.

FIG. 3 is a schematic view of another embodiment of the present invention.

FIG. 4 shows the phase difference (α) and the minimum attainable temperature (Tmin) in the case of the present invention (a) and the case of the Stirling refrigerator (b).
It is a graph which shows the relationship with.

FIG. 5 is a schematic diagram when the present invention is used in a cryopump.

FIG. 6A is a partial sectional view taken along the line XX ′ of the embodiment of the present invention. (B) is a partial cross-sectional view taken along the line YY 'of the embodiment of the present invention.

FIG. 7 is a partial schematic view of an embodiment in which the cold head, pulse tube and regenerator of the present invention are made compact.

FIG. 8 is a schematic diagram of an example of a conventional Stirling refrigerator.

FIG. 9 is a P-V diagram in the refrigerator cycle.

FIG. 10 is a TS ′ diagram in the refrigerator cycle.

[Explanation of symbols]

1,18,37 Compressed space 2,14,34 Crank shaft 3,16,36 Compressed piston 4,17 Compressed cylinder 5,20,38 Radiator 6,22,39,40 Regenerator 7,27 Cold head 8,23 Expansion cylinder 9,24,49 Expansion piston 10,26,46 Expansion space 11,12,15,25,35,47 Connecting rod 13, Seal ring 19,28,32-1,32-2,32-3,32-
4, 37-2, 45 Piping 21, 43, 44 Pulse tube 29 Heat exchanger 30, 54 Cooling fluid 31 Cylinder 33 Piston ring

Claims (7)

[Claims] 1. A compression space having a relatively large capacity formed by a top of at least one compression piston reciprocating by a compression crank driven by external power and a compression cylinder, and an angle from the compression crank. An expansion space having a relatively small volume is formed at the top of an expansion piston that reciprocates by an expansion crank that is interlocked with a phase angle α advanced from 5 ° to 45 °. A pulse tube type Stirling refrigerator in which a radiator, a regenerator, a cold head and a pulse tube are sequentially arranged in between. 2. The pulse tube type Stirling refrigerator according to claim 1, wherein the compression space is a plurality of compression spaces constituted by tops of a plurality of compression pistons. 3. A cylindrical pulse tube, at least a part of which is at least doubled, is disposed in the center of an axis in a convex cylinder having a cold head having two or more stages of cold heads. 2. A regenerator or a regenerator and a radiator are further arranged on the outer peripheral portion of the cylindrical pulse tube, and the configurations of the radiator, the regenerator, the cold head and the pulse tube are integrated. Pulse tube Stirling refrigerator. 4. The pulse tube according to claim 3, wherein the compression space and the expansion space are connected to the integrated radiator, regenerator, cold head and pulse tube by a flexible pipe. Type Stirling refrigerator. 5. The phase angle α has a required freezing temperature of 30 K to
20 ° to 25 °, 50k to 120 in 50K region
The pulse tube type Stirling refrigerator according to claim 1, wherein the range is 25 to 40 in the region of k. 6. The volume ratio of the compression space and the expansion space (compression space volume / expansion space volume) is 5 to 20, preferably 10
The pulse tube type Stirling refrigerator according to any one of claims 1 to 5, characterized in that 7. The pulse tube according to claim 1, wherein the pulse tube is made of any one of stainless steel, a composite material, ceramics or a combination thereof. Type Stirling refrigerator.