JP7186133B2 - Multi-stage pulse tube refrigerator and cold head of multi-stage pulse tube refrigerator - Google Patents

Description

The present invention relates to a multi-stage pulse tube refrigerator and a cold head for a multi-stage pulse tube refrigerator.

A pulse tube refrigerator has, as main components, an oscillating flow source, a regenerator, a pulse tube, and a phase control mechanism. There are several methods for generating an oscillating flow. For example, the so-called GM (Gifford-McMahon) method, which uses a combination of a compressor and a periodic flow switching valve, and the Stirling method, which generates an oscillating flow by means of a harmonically vibrating piston, are known. Also, there are various types of phase control mechanisms such as a double inlet type, an active buffer type, and a 4-valve type.

JP 2014-169852 A

A four-valve pulse tube refrigerator has an intake valve and an exhaust valve connected to the high temperature end of the pulse tube in addition to the intake valve and the exhaust valve connected to the high temperature end of the regenerator. In the case of a multi-stage type, an intake valve and an exhaust valve are provided for each pulse tube of each stage. A four-valve pulse tube refrigerator has a larger number of valves than other types of pulse tube refrigerators, and therefore tends to have a complicated valve configuration and a large size.

A pulse tube refrigerator design is often employed in which these intake and exhaust valves are composed of a single rotary valve. A pair of intake and exhaust valves must be incorporated into the rotary valve to achieve the desired switching between intake and exhaust timing. In addition, the gas flow path communicating with the regenerator formed in the rotary valve and the flow path communicating with the pulse tube are arranged so that the refrigerant gas does not directly flow between the high temperature end of the regenerator and the high temperature end of the pulse tube. are arranged at positions different from each other from the rotation axis of the Thus, gas flow path structures within rotary valves can be quite complex. In the multi-stage type, communication paths to pulse tubes in different stages are often arranged at different radial positions. The diameter of the rotary valve can be larger in two stages than in single stages, and even larger in three stages.

One exemplary object of some aspects of the invention is to provide a pulse tube refrigerator with a simple valve configuration.

According to one aspect of the invention, a multi-stage pulse tube refrigerator includes a compressor having a compressor discharge and a compressor inlet, a first stage pulse tube, a second stage pulse tube, and the first stage. a first stage regenerator having a cold end in communication with the cold end of the pulse tube; and a cold end in communication with the cold end of the second stage pulse tube in series with the first stage regenerator. a second stage regenerator connected thereto; a main pressure switching valve alternately connecting the hot end of said first stage regenerator to said compressor discharge and said compressor inlet; and a pulse tube. a secondary pressure switching valve that alternately connects both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube to the compressor discharge port and the compressor suction port via a communication path; Prepare. The pulse tube communication passage has a branch portion between the high temperature end of the first stage pulse tube, the high temperature end of the second stage pulse tube, and the auxiliary pressure switching valve. It branches into a channel and a second pulse tube channel. The first pulse tube flow path connects the secondary pressure switching valve to the hot end of the first stage pulse tube, and the second pulse tube flow path connects the secondary pressure switching valve to the hot end of the second stage pulse tube. connect to.

According to one aspect of the invention, a coldhead of a multi-stage pulse tube refrigerator includes a first stage pulse tube, a second stage pulse tube, and a cold end in communication with the cold end of the first stage pulse tube. a second stage regenerator having a cold end communicating with the cold end of the second stage pulse tube and connected in series with the first stage regenerator; a regenerator communication passage connecting the high temperature end of the stage regenerator to the main pressure switching valve; and a pulse connecting both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube to the sub pressure switching valve. and a tube communication passage. The pulse tube communication passage has a branch portion between the high temperature end of the first stage pulse tube, the high temperature end of the second stage pulse tube, and the auxiliary pressure switching valve. It branches into a channel and a second pulse tube channel. The first pulse tube flow path connects the secondary pressure switching valve to the hot end of the first stage pulse tube, and the second pulse tube flow path connects the secondary pressure switching valve to the hot end of the second stage pulse tube. connect to.

It should be noted that arbitrary combinations of the above-described constituent elements and mutually replacing the constituent elements and expressions of the present invention in methods, devices, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a pulse tube refrigerator having a simple valve configuration.

1 is a schematic diagram showing a pulse tube refrigerator according to an embodiment; FIG. 2 illustrates exemplary valve timing that may be applied to the valve portion of the pulse tube refrigerator shown in FIG. 1; FIG. FIG. 2 is a schematic diagram showing an exemplary rotary valve that can be applied to the valve portion of the pulse tube refrigerator shown in FIG. 1; 4(a) and 4(b) are schematic diagrams showing the valve stator and valve rotor, respectively, of the rotary valve shown in FIG. It is a schematic diagram showing another example of the pulse tube refrigerator according to the embodiment. FIG. 4 is a schematic diagram showing an example of a connection configuration of buffer lines that can be applied to the pulse tube refrigerator according to the embodiment; It is a schematic diagram showing a further example of the pulse tube refrigerator according to the embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience in order to facilitate explanation, and should not be construed as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

FIG. 1 is a schematic diagram showing a pulse tube refrigerator 10 according to an embodiment. A pulse tube refrigerator 10 includes a cold head 11 and a compressor 12 .

The pulse tube refrigerator 10 is, for example, a GM (Gifford-McMahon) four-valve pulse tube refrigerator. Thus, the pulse tube refrigerator 10 comprises a main pressure switching valve 14, a first stage regenerator 16, a first stage pulse tube 18, a secondary pressure switching valve 20 and optionally a first flow control element 21. and a one-stage phase control mechanism. Compressor 12 and main pressure switching valve 14 constitute an oscillating flow source of pulse tube refrigerator 10 . Compressor 12 is shared by the oscillatory flow source and the first stage phase control mechanism.

Also, the pulse tube refrigerator 10 is a two-stage refrigerator, and includes a second-stage regenerator 22, a second-stage pulse tube 24, and a second-stage phase control mechanism optionally having a second flow rate adjustment element 27. , is further provided. Compressor 12 and secondary pressure switching valve 20 are also shared by the second stage phase control mechanism.

The flow control elements (21, 27) include, for example, orifices or flow resistances such as throttle valves. The flow resistance may be fixed or adjustable.

In this document, the terms vertical direction A and horizontal direction B are used for convenience in describing the positional relationship between the components of the pulse tube refrigerator 10 . Typically, longitudinal direction A and lateral direction B correspond to the axial and radial directions of the pulse tubes (18, 24) and regenerators (16, 22), respectively. However, the vertical direction A and the horizontal direction B may be directions that are approximately orthogonal to each other, and are not required to be strictly orthogonal. In addition, the notation of the vertical direction A and the horizontal direction B does not limit the orientation of the pulse tube refrigerator 10 installed at its place of use. The pulse tube refrigerator 10 can be installed in any desired orientation. and the lateral direction B may be oriented horizontally and vertically, respectively. Alternatively, the vertical direction A and the horizontal direction B can be installed in different oblique directions.

Two regenerators (16, 22) are connected in series and extend in longitudinal direction A. The two pulse tubes (18, 24) each extend in longitudinal direction A. The first stage regenerator 16 is arranged in the transverse direction B in parallel with the first stage pulse tube 18 , and the second stage regenerator 22 is arranged in the transverse direction B in parallel with the second stage pulse tube 24 . The first stage pulse tube 18 has approximately the same length in the longitudinal direction A as the first stage regenerator 16, and the second stage pulse tube 24 extends in the longitudinal direction A between the first stage regenerator 16 and the second stage regenerator. It has approximately the same length as the total length of 22. The regenerators (16, 22) and pulse tubes (18, 24) are arranged generally parallel to each other.

In FIG. 1, the first stage pulse tube 18 and the second stage pulse tube 24 are arranged on both sides of the regenerators (16, 22), but this is merely for ease of illustration. do not have. Typically, the regenerators (16, 22), first stage pulse tube 18 and second stage pulse tube 24 may be arranged to form a triangle when viewed in longitudinal direction A.

The compressor 12 has a compressor discharge port 12a and a compressor suction port 12b, and is configured to compress the recovered low-pressure PL working gas to generate a high-pressure PH working gas. The working gas is supplied from the compressor discharge port 12a through the first stage regenerator 16 to the first stage pulse tube 18, and the working gas flows from the first stage pulse tube 18 through the first stage regenerator 16 to the compressor suction port 12b. be recovered. Further, the working gas is supplied from the compressor discharge port 12a to the second stage pulse tube 24 through the first stage regenerator 16 and the second stage regenerator 22, and from the second stage pulse tube 24 to the second stage regenerator 22 and the The working gas is recovered through the first stage regenerator 16 to the compressor suction port 12b.

Compressor discharge port 12a and compressor suction port 12b function as a high pressure source and a low pressure source of pulse tube refrigerator 10, respectively. The working gas is also called refrigerant gas, for example helium gas. In general, both high pressure PH and low pressure PL are significantly higher than atmospheric pressure.

The main pressure switching valve 14 has a main intake opening/closing valve V1 and a main exhaust opening/closing valve V2. The sub pressure switching valve 20 has a sub intake opening/closing valve V3 and a sub exhaust opening/closing valve V4.

The pulse tube refrigerator 10 is provided with a high pressure line 13a and a low pressure line 13b. A high pressure PH working gas flows from the compressor 12 to the cold head 11 through the high pressure line 13a. A low-pressure PL working gas flows from the cold head 11 to the compressor 12 through the low-pressure line 13b. A high-pressure line 13a connects the compressor discharge port 12a to the intake on-off valves (V1, V3). The low pressure line 13b connects the compressor suction port 12b to the exhaust on-off valves (V2, V4).

The first stage regenerator 16 has a first stage regenerator hot end 16a and a first stage regenerator cold end 16b. It extends in the longitudinal direction A. First stage regenerator hot end 16a and first stage regenerator cold end 16b may also be referred to as first and second ends of first stage regenerator 16, respectively. Similarly, the second stage regenerator 22 has a second stage regenerator hot end 22a and a second stage regenerator cold end 22b, with a second stage regenerator hot end 22a to a second stage regenerator cold end 22a. 22b in longitudinal direction A. Second stage regenerator hot end 22a and second stage regenerator cold end 22b may also be referred to as first and second ends of second stage regenerator 22, respectively. The first stage regenerator low temperature end 16b communicates with the second stage regenerator high temperature end 22a.

The first stage pulse tube 18 has a first stage pulse tube hot end 18a and a first stage pulse tube cold end 18b, with a pulse from first stage pulse tube hot end 18a to first stage pulse tube cold end 18b. It extends in the longitudinal direction A. First stage pulse tube hot end 18a and first stage pulse tube cold end 18b may also be referred to as first and second ends of first stage pulse tube 18, respectively.

Similarly, the second stage pulse tube 24 has a second stage pulse tube hot end 24a and a second stage pulse tube cold end 24b, and has a second stage pulse tube hot end 24a to a second stage pulse tube cold end 24a. 24b in longitudinal direction A. Second stage pulse tube hot end 24a and second stage pulse tube cold end 24b may also be referred to as first and second ends of second stage pulse tube 24, respectively.

In an exemplary configuration, the regenerators (16, 22) are cylindrical tubes filled with regenerator material, and the pulse tubes (18, 24) are hollow cylindrical tubes.

Both ends of the pulse tubes (18, 24) may be provided with rectifiers for equalizing the working gas flow velocity distribution in a plane perpendicular to the axial direction of the pulse tube or adjusting it to a desired distribution. . This rectifier also functions as a heat exchanger.

The coldhead 11 comprises a first stage cooling stage 28 and a second stage cooling stage 30 .

First stage regenerator 16 and first stage pulse tube 18 extend in the same direction from first stage cooling stage 28, and first stage regenerator hot end 16a and first stage pulse tube hot end 18a are connected to the first stage. It is arranged on the same side with respect to the cooling stage 28 . In this manner, the first stage regenerator 16, first stage pulse tube 18, and first stage cooling stage 28 are arranged in a U-shape. Similarly, second stage regenerator 22 and second stage pulse tube 24 extend in the same direction from second stage cooling stage 30, second stage regenerator hot end 22a and second stage pulse tube hot end 24a It is arranged on the same side with respect to the second stage cooling stage 30 . Thus, the second stage regenerator 22, the second stage pulse tube 24, and the second stage cooling stage 30 are arranged in a U shape.

First stage pulse tube cold end 18 b and first stage regenerator cold end 16 b are structurally connected and thermally coupled by first stage cooling stage 28 . In the first stage cooling stage 28, a first stage communication passage 29 communicates between the first stage regenerator low temperature end 16b and the first stage pulse tube low temperature end 18b so that the working gas can flow between them. is formed.

Similarly, second stage pulse tube cold end 24 b and second stage regenerator cold end 22 b are structurally connected and thermally coupled by second stage cooling stage 30 . In the second stage cooling stage 30, a second stage communication passage 31 communicates between the second stage regenerator low temperature end 22b and the second stage pulse tube low temperature end 24b so that the working gas can flow between them. is formed.

The cooling stages (28, 30) are made of a metal material with high thermal conductivity, for example copper. The cylindrical parts of the regenerators (16, 22) and the pulse tubes (18, 24) are made of a material having a lower thermal conductivity than the cooling stages (28, 30), such as a metal material such as stainless steel.

An object (not shown) to be cooled is thermally coupled to the second cooling stage 30 . The object may be placed directly on the second stage cooling stage 30 or thermally coupled to the second stage cooling stage 30 via a rigid or flexible heat transfer member. The pulse tube refrigerator 10 can cool the object by conduction cooling from the second stage cooling stage 30 . Note that the object cooled by the pulse tube refrigerator 10 may be, as non-limiting examples, a superconducting electromagnet or other superconducting device, or an infrared imager or other sensor. The pulse tube refrigerator 10 can also cool gas or liquid contacting the second cooling stage 30 .

It will also be appreciated that objects other than those cooled by the second stage cooling stage 30 may be cooled by the first stage cooling stage 28 . For example, first stage cooling stage 28 may be thermally coupled with a radiation shield to reduce or prevent heat entry into second stage cooling stage 30 .

On the other hand, the first stage regenerator high temperature end 16a, the first stage pulse tube high temperature end 18a, and the second stage pulse tube high temperature end 24a are connected by a flange portion . The flange portion 36 is attached to a support portion 38 such as a support table or a support wall on which the pulse tube refrigerator 10 is installed. The support 38 may be the wall material or other part of an insulated or vacuum vessel containing the cooling stages (28, 30) and the object to be cooled.

Pulse tubes (18, 24) and regenerators (16, 22) extend from one major surface of flange portion 36 to cooling stages (28, 30), and valve portion 40 extends from the other major surface of flange portion 36. is provided. The valve portion 40 accommodates the main pressure switching valve 14 and the sub pressure switching valve 20 . Thus, if the support 38 forms part of an insulated or vacuum vessel, when the flange 36 is attached to the support 38, the pulse tubes (18, 24), regenerators (16, 22), and The cooling stages (28, 30) are housed within the vessel and the valve section 40 is located outside the vessel.

It should be noted that the valve portion 40 need not be directly attached to the flange portion 36 . The valve section 40 may be arranged separately from the cold head 11 of the pulse tube refrigerator 10 and connected to the cold head 11 by rigid or flexible piping. Thus, the phase control mechanism of the pulse tube refrigerator 10 may be arranged separately from the cold head 11 .

The main pressure selector valve 14 is configured to alternately connect the first stage regenerator hot end 16a to the compressor discharge 12a and compressor suction 12b to produce pressure oscillations in the pulse tubes (18, 24). It is The main pressure switching valve 14 is configured such that when one of the main intake opening/closing valve V1 and the main exhaust opening/closing valve V2 is open, the other is closed. The main pressure switching valve 14 is connected via a regenerator communication passage 32 to the first stage regenerator high temperature end 16a. A main intake on/off valve V1 connects the compressor discharge 12a to the first stage regenerator hot end 16a, and a main exhaust on/off valve V2 connects the compressor inlet 12b to the first stage regenerator hot end 16a.

When the main intake opening/closing valve V1 is open, working gas is supplied from the compressor discharge port 12a to the regenerators (16, 22) through the high pressure line 13a, the main intake opening/closing valve V1, and the regenerator communication passage 32. The working gas is further supplied from the first stage regenerator 16 to the first stage pulse tube 18 through the first stage communication passage 29, and from the second stage regenerator 22 to the second stage pulse tube through the second stage communication passage 31. 24. On the other hand, when the main exhaust opening/closing valve V2 is open, the working gas is recovered from the pulse tube (18, 24) to the compressor suction port 12b through the regenerators (16, 22), the main exhaust opening/closing valve V2, and the low pressure line 13b. be done.

The auxiliary pressure switching valve 20 alternately connects both the first stage pulse tube high temperature end 18a and the second stage pulse tube high temperature end 24a to the compressor discharge port 12a and the compressor suction port 12b via the pulse tube communication passage 34. do. The auxiliary pressure switching valve 20 is configured such that when one of the auxiliary intake opening/closing valve V3 and the auxiliary exhaust opening/closing valve V4 is open, the other is closed. An auxiliary intake on/off valve V3 connects the compressor discharge port 12a to both the first stage pulse tube high temperature end 18a and the second stage pulse tube high temperature end 24a, and an auxiliary exhaust on/off valve V4 connects the compressor suction port 12b to the first stage pulse tube high temperature end 24a. It connects to both the pulse tube hot end 18a and the second stage pulse tube hot end 24a.

The pulse tube communication passage 34 has a branch portion 42 between the first stage pulse tube high temperature end 18 a and the second stage pulse tube high temperature end 24 a and the auxiliary pressure switching valve 20 . The pulse tube communication passage 34 branches at a branch portion 42 into a first pulse tube flow path 44 and a second pulse tube flow path 46 . A first pulse tube flow path 44 connects the secondary pressure switching valve 20 to the first stage pulse tube hot end 18a, and a second pulse tube flow path 46 connects the secondary pressure switching valve 20 to the second stage pulse tube hot end 24a. do. The first pulse tube channel 44 has a first flow control element 21 and the second pulse tube channel 46 has a second flow control element 27 .

When the auxiliary intake on-off valve V3 is open, the first stage pulse tube flows from the compressor discharge port 12a through the high pressure line 13a, the auxiliary intake on-off valve V3, the first pulse tube flow path 44, and the first stage pulse tube high temperature end 18a. A working gas is supplied to 18 . On the other hand, when the auxiliary exhaust opening/closing valve V4 is open, the working gas is recovered from the first stage pulse tube 18 to the compressor suction port 12b through the first stage pulse tube high temperature end 18a, the auxiliary exhaust opening/closing valve V4, and the low pressure line 13b. be done.

Further, when the auxiliary intake on/off valve V3 is open, the second stage air is supplied from the compressor discharge port 12a through the high pressure line 13a, the auxiliary intake on/off valve V3, the second pulse tube flow path 46, and the second stage pulse tube high temperature end 24a. A working gas is supplied to the pulse tube 24 . On the other hand, when the auxiliary exhaust opening/closing valve V4 is open, the working gas is recovered from the second stage pulse tube 24 to the compressor suction port 12b through the second stage pulse tube high temperature end 24a, the auxiliary exhaust opening/closing valve V4, and the low pressure line 13b. be done.

FIG. 2 is a diagram showing exemplary valve timing that may be applied to the valve section 40 of the pulse tube refrigerator 10 shown in FIG. One refrigeration cycle of the pulse tube refrigerator 10 is divided into a first standby period W1, an intake period A1, a second standby period W2, and an exhaust period A2.

In FIG. 2, for the sake of convenience, one cycle of the refrigeration cycle is illustrated as starting at the start timing _t0 of the first standby period W1 and ending at the end timing _t8 of the exhaust period A2. The end timing _t8 of the exhaust period A2 is the start timing _t0 of the next refrigeration cycle.

The main pressure switching valve 14 is configured to sequentially repeat a first waiting period W1, an intake period A1, a second waiting period W2, and an exhaust period A2. The auxiliary pressure switching valve 20 is opened prior to the main pressure switching valve 14 and closed prior to the main pressure switching valve 14 . In FIG. 2, the hatched section indicates that the valve is open.

During the first standby period W1, both the main intake opening/closing valve V1 and the main exhaust opening/closing valve V2 are closed, and the first stage regenerator high temperature end 16a is connected to both the compressor discharge port 12a and the compressor suction port 12b. not. During the intake period A1, the main intake opening/closing valve V1 is opened, the main exhaust opening/closing valve V2 is closed, and the first stage regenerator high temperature end 16a is connected to the compressor discharge port 12a. During the second waiting period W2, both the main intake opening/closing valve V1 and the main exhaust opening/closing valve V2 are closed again, and the first stage regenerator high temperature end 16a is connected to both the compressor discharge port 12a and the compressor suction port 12b. Not connected. During the exhaust period A2, the main intake opening/closing valve V1 is closed, the main exhaust opening/closing valve V2 is opened, and the first stage regenerator high temperature end 16a is connected to the compressor suction port 12b.

The auxiliary pressure switching valve 20 switches between the first stage pulse tube high temperature end 18a and the second stage pulse tube high temperature end 24a before 1/2 (or 1/3 or 1/4) of the first waiting period W1 elapses. Both are connected to the compressor discharge port 12a. The auxiliary pressure switching valve 20 breaks this connection before the intake period A1 elapses. In addition, the auxiliary pressure switching valve 20 switches between the first stage pulse tube high temperature end 18a and the second stage pulse tube high temperature end until 1/2 (or 1/3, or 1/4) of the second standby period W2 elapses. 24a are both connected to the compressor intake 12b. The auxiliary pressure switching valve 20 breaks this connection before the exhaust period A2 elapses.

As shown in FIG. 2, the timing t ₁ for opening the auxiliary intake valve V3 is set between the start timing t ₀ and (t ₂ −t ₀ )/2 of the first waiting period W1. Here, (t ₂ −t ₀ )/2 is half the difference between the start timing t ₀ of the first waiting period W1 and the start timing t ₂ of the intake period A1. Alternatively, the timing t ₁ for opening the auxiliary intake on-off valve V3 may be closer to t ₀ , for example, between t ₀ and (t ₂ −t ₀ )/3, or between t ₀ and (t ₂ −t ₀ ). /4. The timing _t3 for closing the auxiliary intake opening/closing valve V3 is set during the intake period A1 (that is, between _t2 and _t4 ).

The timing t ₅ for opening the auxiliary exhaust opening/closing valve V4 is set between the start timing t ₄ of the second waiting period W2 and (t ₆ −t ₄ )/2. Here, (t ₆ −t ₄ )/2 is half the difference between the start timing t ₄ of the second waiting period W2 and the start timing t ₆ of the exhaust period A2. Alternatively, the timing t ₅ for opening the auxiliary exhaust on-off valve V4 may be closer to t ₄ , for example, between t ₄ and (t ₆ −t ₄ )/3, or between t ₄ and (t ₆ −t ₄ ). /4. The timing _t7 for closing the auxiliary exhaust opening/closing valve V4 is set during the exhaust period A2 (that is, between _t6 and _t8 ).

A typical two-stage pulse tube refrigerator has two auxiliary pressure switching valves arranged in parallel, one connected to the first stage pulse tube and the other connected to the second stage pulse tube. In such a typical design, first stage refrigeration capacity may be maximized by leading the valve timing of the first stage secondary pressure reversal valve by a very small amount relative to the main pressure reversal valve. As illustrated by the dashed arrow D, the timing of opening the first stage auxiliary pressure switching valve is set between (t ₂ −t ₀ )/2 and t ₂ , for example. Unlike the secondary pressure switching valve 20 according to the embodiment, the first stage secondary pressure switching valve is opened after 1/2 of the first standby period W1 has elapsed.

However, according to the study of the present inventor, the auxiliary intake opening/closing valve V3 is opened before 1/2 (or 1/3, or 1/4) of the first waiting period W1 elapses, and the auxiliary exhaust opening/closing valve V4 is opened. is opened before 1/2 (or 1/3, or 1/4) of the second waiting period W2 has elapsed, thereby realizing a refrigeration performance equivalent to that of the typical pulse tube refrigerator described above. can be done.

Therefore, in the pulse tube refrigerator 10 according to the embodiment, the auxiliary pressure switching valve 20 is shared by the first stage pulse tube 18 and the second stage pulse tube 24, thereby simplifying the structure of the valve section 40. , can provide good refrigeration performance, which is advantageous.

The valve timings of these valves (V1 to V4) are not limited to those shown in FIG. 2, and various valve timings applicable to existing 4-valve pulse tube refrigerators can be adopted. .

Various specific configurations of the valves (V1 to V4) are possible. For example, the group of valves (V1-V4) may take the form of a plurality of individually controllable valves, such as electromagnetic on-off valves. The valves (V1-V4) may be configured as rotary valves.

FIG. 3 is a schematic diagram showing an exemplary rotary valve that can be applied to the valve section 40 of the pulse tube refrigerator 10 shown in FIG. 4(a) and 4(b) are schematic diagrams showing the valve stator 48 and valve rotor 50, respectively, of the rotary valve shown in FIG. FIGS. 4(a) and 4(b) show the flow path arrangement on the valve sliding surface 52 of the rotary valve. As can be seen from the figure, this rotary valve is constructed so that one refrigerating cycle is performed by rotating it by 180 degrees.

A valve stator 48 and a valve rotor 50 of the rotary valve are accommodated in a valve housing 54 and are arranged adjacent to each other so as to be in surface contact with each other on a valve sliding surface 52 . The valve stator 48 is fixed to the valve housing 54 . A valve drive motor 56 is installed outside the valve housing 54 , and an output shaft of the valve drive motor 56 extends through the valve housing 54 to the valve rotor 50 .

A pressure chamber 58 is formed inside the valve housing 54 , and the valve rotor 50 and the valve stator 48 are arranged in the pressure chamber 58 . As an example, the pressure chamber 58 is connected to the low pressure line 13b to introduce the low pressure PL. The valve stator 48 is connected to the high-pressure line 13 a , the regenerator communication passage 32 and the pulse tube communication passage 34 .

A high-pressure introduction passage 48 a extends through the center of the valve stator 48 along the rotation axis of the valve rotor 50 . Two regenerator communication holes 48 b and two pulse tube communication holes 48 c penetrate through the outer peripheral portion of the valve stator 48 in the direction of the rotation axis of the valve rotor 50 . The two regenerator communication holes 48b are arranged at intervals of 180 degrees in the circumferential direction on the circumference around the rotation axis of the valve rotor 50. As shown in FIG. The two pulse tube communication holes 48c are arranged at intervals of 180 degrees in the circumferential direction on the same circumference as the regenerator communication holes 48b. However, the regenerator communication hole 48b and the pulse tube communication hole 48c are arranged with a desired angle in the circumferential direction.

Further, the valve rotor 50 is formed with a high-pressure recess 50a and two low-pressure recesses 50b. The high pressure recess 50 a is formed on the valve sliding surface 52 along the diameter of the valve sliding surface 52 . The high-pressure recess 50 a is sealed from the pressure chamber 58 by surface contact between the valve stator 48 and the valve rotor 50 and does not communicate with the pressure chamber 58 . The high pressure line 13 a is always connected to the high pressure recess 50 a of the valve rotor 50 through the high pressure introduction passage 48 a of the valve stator 48 . The two low-pressure recesses 50b are formed on the outer periphery of the valve rotor 50 and form part of the pressure chambers 58. As shown in FIG. Therefore, the low pressure line 13b is always connected to the low pressure recess 50b.

Several sealing members (for example, O-rings) are mounted between the valve stator 48 and the valve housing 54, and between the high-pressure line 13a, the regenerator communication passage 32, and the pulse tube communication passage 34 inside the valve section 40. direct working gas flow is prevented.

The drive of the valve drive motor 56 rotates the output shaft, whereby the valve rotor 50 rotates and slides with respect to the valve stator 48 . As the valve rotor 50 rotates (indicated by an arrow R), the valve sliding surface 52 periodically switches the flow channel connection.

Since the high-pressure recess 50a and the low-pressure recess 50b of the valve rotor 50 alternately pass through the regenerator communication hole 48b of the valve stator 48, the valve section 40 alternately connects the high-pressure line 13a and the low-pressure line 13b to the regenerator communication passage 32. do. Thus, valve assembly 40 is operable to alternately connect first stage regenerator hot end 16a to compressor discharge 12a and compressor inlet 12b.

Since the high-pressure recess 50a and the low-pressure recess 50b of the valve rotor 50 alternately pass through the pulse tube communication hole 48c of the valve stator 48, the valve section 40 alternately connects the high-pressure line 13a and the low-pressure line 13b to the pulse tube communication passage 34. connect to. As described above, pulse tube communication passage 34 has branch 42 , first pulse tube flow path 44 and second pulse tube flow path 46 . Thus, valve assembly 40 is operable to alternately connect both first stage pulse tube hot end 18a and second stage pulse tube hot end 24a to compressor discharge 12a and compressor suction 12b.

A specific flow path configuration of the valve portion 40 as a rotary valve is not limited to the above-described specific example, and various configurations are possible. For example, in the above description, the low pressure line 13b is connected to the pressure chamber 58, and the high pressure line 13a is connected to the valve stator 48. Conversely, the low pressure line 13b is connected to the valve stator 48, A configuration in which the high-pressure line 13a is connected to the chamber 58 is also possible.

Thus, in the pulse tube refrigerator 10 according to the embodiment, the auxiliary pressure switching valve 20 is shared by the first stage pulse tube 18 and the second stage pulse tube 24 . The pulse tube communication passage 34 has a branch portion 42 between the first stage pulse tube high temperature end 18 a and the second stage pulse tube high temperature end 24 a and the auxiliary pressure switching valve 20 . The pulse tube communication passage 34 branches at a branch portion 42 into a first pulse tube flow path 44 and a second pulse tube flow path 46 . A first pulse tube flow path 44 connects the secondary pressure switching valve 20 to the first stage pulse tube hot end 18a, and a second pulse tube flow path 46 connects the secondary pressure switching valve 20 to the second stage pulse tube hot end 24a. do. Therefore, although the pulse tube refrigerator 10 is a multistage pulse tube refrigerator, it is possible to employ the valve section 40 having the same structure as that used in a single stage pulse tube refrigerator. Therefore, a pulse tube refrigerator with a simple valve configuration is provided.

A first flow rate adjusting element 21 is provided in the first pulse tube flow path 44 , and a second flow rate adjusting element 27 is provided in the second pulse tube flow path 46 . Fine adjustment of the phase control in each of the first stage and the second stage of the pulse tube refrigerator 10 is performed by appropriately setting the flow path resistances of the first flow rate adjusting element 21 and the second flow rate adjusting element 27 individually in advance. be able to. This helps maximize the refrigeration capacity of each of the first and second stages of pulse tube refrigerator 10 .

FIG. 5 is a schematic diagram showing another example of the pulse tube refrigerator 10 according to the embodiment. The valve section 40 (that is, the main pressure switching valve 14 and the sub pressure switching valve 20) is detachably connected to the cold head 11. As shown in FIG.

The regenerator communication passage 32 includes regenerator connection piping 60 that connects the main pressure switching valve 14 to the first stage regenerator 16. The regenerator connection piping 60 connects the main pressure switching valve 14 and the first stage regenerator high temperature end. 16a can be attached and detached. Both ends of the regenerator connecting pipe 60 are detachably attached to the main pressure switching valve 14 and the first stage regenerator hot end 16a via detachable joints 61 such as self-sealing couplings. The regenerator connecting pipe 60 may be a flexible pipe or a rigid pipe.

The pulse tube communication passage 34 includes a pulse tube connection pipe 62 that connects the sub pressure switching valve 20 to the branch portion 42, and the pulse pipe connection pipe 62 is attachable/detachable to each of the sub pressure switch valve 20 and the branch portion 42. . Both ends of the pulse tube connecting pipe 62 are detachably attached to the auxiliary pressure switching valve 20 and the branch 42 via detachable joints 63 such as self-sealing couplings. The pulse tube connecting pipe 62 may be a flexible pipe or a rigid pipe.

As mentioned above, a typical two-stage pulse tube refrigerator has two secondary pressure switching valves, one connected to the first stage pulse tube and the other connected to the second stage pulse tube. Such a typical design requires a connecting line for the first stage pulse tube and a connecting line for the second stage pulse tube. Since the volume of the piping is a dead volume that does not contribute to the refrigerating capacity, it is desirable that the volume be as small as possible.

In the pulse tube refrigerator 10 according to the embodiment, the auxiliary pressure switching valve 20 is shared by the first stage pulse tube 18 and the second stage pulse tube 24 . Therefore, the auxiliary pressure switching valve 20 can be connected to two pulse tubes (18, 24) with one pulse tube connecting pipe 62. FIG. Compared to a typical pulse tube refrigerator, the dead volume due to connecting pipes can be halved, and the cooling capacity can be improved. Also, pressure loss due to piping can be reduced.

Further, since the valve section 40 is removable from the cold head 11, the operator can remove the valve section 40 from the cold head 11 for maintenance. Alternatively, the operator can remove the valve section 40 from the coldhead 11 and replace it with another new or maintained valve section 40 .

By the way, in a four-valve pulse tube refrigerator, a working gas circulation path can be formed including a compressor, a pulse tube, and a regenerator. A gas flow with a direct current component can be generated in such a circulation path, also referred to as a "DC flow". DC flow can affect the refrigeration performance of pulse tube refrigerators. In particular, when the DC flow includes a working gas flow penetrating from the pulse tube hot end to the pulse tube cold end, such working gas flow provides significant heat input from the pulse tube hot end to the pulse tube cold end. and the refrigeration efficiency of the pulse tube refrigerator can be reduced.

Therefore, the pulse tube refrigerator 10 may include a DC flow control channel 66 . A DC flow control path 66 is arranged in parallel with the secondary pressure selector valve 20 and connects both the first stage pulse tube hot end 18a and the second stage pulse tube hot end 24a to the compressor inlet 12b. The DC flow control channel 66 branches from the pulse tube communication channel 34 between the auxiliary pressure switching valve 20 and the branch portion 42 . In this manner, the DC flow control channel 66 may also be shared between the first stage pulse tube 18 and the second stage pulse tube 24 .

The DC flow control flow path 66 has a DC flow on-off valve 68 and a DC flow adjustment element 70 provided in parallel with the sub-exhaust on-off valve V4 of the sub-pressure switching valve 20 . In an exemplary valve timing, the DC flow on-off valve 68 may be identical to the valve timing of the secondary exhaust on-off valve V4 shown in _{FIG .} may be open and closed at other times). Alternatively, the DC flow on/off valve 68 may be temporarily opened while the secondary exhaust on/off valve V4 is open. The DC flow regulating element 70, like the first flow regulating element 21, includes a flow resistance, such as an orifice or throttle valve, which may be fixed or adjustable. good too.

As shown in FIG. 5, when the pulse tube connection pipe 62 is used to connect the cold head 11 and the valve unit 40, the DC flow control flow path 66 is connected to the auxiliary pressure switching valve 20 and the pulse tube. It may branch from the pulse tube communication passage 34 to the connection pipe 62 (the joint 63 on the side of the auxiliary pressure switching valve 20). In this way, there is no need to provide an additional connecting pipe for the DC flow control channel 66 in parallel with the pulse tube connecting pipe 62 .

A DC flow control channel 66 may be incorporated into a rotary valve. In that case, as indicated by the dashed line in FIG. 4A, it may be provided radially adjacent to (for example, radially inwardly of) the pulse tube communication hole 48c of the valve stator 48 .

FIG. 6 is a schematic diagram showing an example of the connection configuration of the buffer line 72 that can be applied to the pulse tube refrigerator 10 according to the embodiment.

A buffer line 72 may be connected to the first stage pulse tube hot end 18a. Buffer line 72 has a buffer volume 72a, such as a buffer tank, and a buffer line flow control element 72b, such as an orifice. Buffer volume 72a serves as an intermediate pressure source of working gas having an intermediate pressure between high PH and low PL (eg, the average pressure between high PH and low PL). Thus, working gas flows through the buffer line 72 between the first stage pulse tube 18 and the buffer volume 72a in response to the pressure difference between the first stage pulse tube hot end 18a and the buffer volume 72a.

A first connection port 74 and a second connection port 76 are provided at the first stage pulse tube high temperature end 18a. The first connection port 74 and the second connection port 76 are located at different positions. The first connection port 74 is connected to the first pulse tube channel 44 of the pulse tube communication passage 34 , and the second connection port 76 is connected to the buffer volume 72 a through the buffer line 72 . Thus, instead of the buffer line 72 joining the pulse tube communication passage 34 between the secondary pressure switching valve 20 and the first stage pulse tube high temperature end 18a, the pulse tube communication passage 34 and the buffer line 72 are separated. It is connected to the first stage pulse tube hot end 18a.

The first connection port 74 and the second connection port 76 are located at radially different positions on the first stage pulse tube hot end 18a. A first connection port 74 is provided radially outward at a first distance C1 from the center 78 of the first stage pulse tube high temperature end 18a, and a second connection port 76 is provided at the center of the first stage pulse tube high temperature end 18a. It is provided at a second distance C2 radially outward from 78 . Here, the first distance C1 and the second distance C2 indicate the lengths from the center 78 of the first stage pulse tube high temperature end 18a to the centers of the first connection port 74 and the second connection port 76, respectively. Both the first distance C1 and the second distance C2 are less than the radius of the first stage pulse tube 18 so that the first connection port 74 and the second connection port 76 are located on the upper surface of the first stage pulse tube hot end 18a. .

The first distance C1 is longer than the second distance C2. Thus, the second port 76 is located closer to the center 78 of the first stage pulse tube hot end 18a, and the first port 74 is closer to the first stage pulse tube hot end 18a than the second port 76 is. located near the perimeter. For example, first distance C1 may be greater than half the radius of first stage pulse tube 18 . The second distance C 2 may be less than half the radius of the first stage pulse tube 18 . A second connection port 76 may be provided at the center 78 of the first stage pulse tube hot end 18a. In that case, the second distance C2 is zero.

The first connection port 74 and the second connection port 76 are both connected to the first stage pulse tube hot end such that the working gas flows in the axial direction of the first stage pulse tube 18 through the first connection port 74 and the second connection port 76 respectively. 18a.

In one exemplary design, instead of connecting the buffer line 72 directly to the first stage pulse tube hot end 18a, the buffer line 72 joins the pulse tube communication passage 34 (e.g., the first pulse tube flow path 44). may be However, in this case, the working gas flowing through the buffer line 72 from the buffer volume 72a to the first stage pulse tube high temperature end 18a also draws in the working gas from the pulse tube communication passage 34. DC flow towards the can be encouraged. Such an effect can become more pronounced as the flow rate of the working gas flowing through the buffer line 72 increases.

In contrast, by providing the first connection port 74 and the second connection port 76 as described above and individually connecting the pulse tube communication path 34 and the buffer line 72 to the first stage pulse tube high temperature end 18a, the DC The flow can be reduced and the refrigeration efficiency of the pulse tube refrigerator 10 can be improved.

Similarly, a second stage buffer line may be connected to the second stage pulse tube 24, and a first connection port 74 and a second connection port 76 may be provided at the second stage pulse tube hot end 24a. .

FIG. 7 is a schematic diagram showing another example of the pulse tube refrigerator 10 according to the embodiment. This pulse tube refrigerator 10 is a three-stage pulse tube refrigerator. Therefore, the cold head 11 includes a third stage regenerator 80 and a third stage pulse tube 82 in addition to the components described with reference to FIGS. 1 and 5 . The third stage regenerator 80 is connected in series with the second stage regenerator 22 . The cold end of the third stage regenerator 80 communicates with the cold end of the third stage pulse tube 82 through a third stage communication passage 84 .

The auxiliary pressure switching valve 20 also alternately connects the high temperature end of the third stage pulse tube 82 to the compressor discharge port 12a and the compressor suction port 12b via the pulse tube communication passage 34. As shown in FIG. The pulse tube communication passage 34 further branches into a third pulse tube flow path 86 at the branching portion 42 , and the third pulse tube flow path 86 connects the auxiliary pressure switching valve 20 to the high temperature end of the third stage pulse tube 82 . A third flow control element 88 is provided in the third pulse tube flow path 86 .

In this manner, the secondary pressure switching valve 20 is shared not only by the first stage pulse tube 18 and the second stage pulse tube 24 but also by the third stage pulse tube 82 . Therefore, it is possible to provide the pulse tube refrigerator 10 having a simple valve structure.

The present invention has been described above based on the examples. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that various design changes and modifications are possible, and that such modifications are within the scope of the present invention. By the way. Various features described in relation to one embodiment are also applicable to other embodiments. A new embodiment resulting from a combination has the effects of each of the combined embodiments.

For example, the detachable valve arrangement described with reference to FIG. 5 is equally applicable to the three-stage pulse tube refrigerator 10 shown in FIG.

Both the main pressure switching valve 14 and the sub pressure switching valve 20 are detachable from the cold head 11 in FIG. However, when the main pressure switching valve 14 and the sub pressure switching valve 20 are separate valves, at least one of the main pressure switching valve 14 and the sub pressure switching valve 20 is detachably connected to the cold head 11. good too.

Although the present invention has been described using specific terms based on the embodiment, the embodiment only shows one aspect of the principle and application of the present invention, and the embodiment does not include the claims. Many variations and rearrangements are permissible without departing from the spirit of the invention as defined in its scope.

10 Pulse tube refrigerator 11 Cold head 12 Compressor 12a Compressor discharge port 12b Compressor suction port 14 Main pressure switching valve 16 First stage regenerator 18 First stage pulse tube 20 Secondary pressure switching valve 21 first flow rate adjustment element 22 second stage regenerator 24 second stage pulse tube 27 second flow rate adjustment element 32 regenerator communication passage 34 pulse tube communication passage 42 branch 44 first pulse tube flow path 46 second pulse tube flow path 62 pulse tube connecting pipe 66 DC flow control flow path 80 third stage regenerator 82 third stage pulse tube 86 third pulse tube flow path A1 intake period , A2 exhaust period, W1 first waiting period, W2 second waiting period.

Claims (7)

a compressor having a compressor discharge and a compressor suction;
a first stage pulse tube, a second stage pulse tube, a first stage regenerator having a cold end communicating with the cold end of the first stage pulse tube, and communicating with the cold end of the second stage pulse tube. a second stage regenerator connected in series with the first stage regenerator;
a main pressure switching valve that alternately connects the hot end of the first stage regenerator to the compressor discharge and the compressor suction;
a secondary pressure switching valve that alternately connects both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube to the compressor discharge port and the compressor suction port via a pulse tube communication passage; , and
The pulse tube communication passage has a branch portion between the high temperature end of the first stage pulse tube, the high temperature end of the second stage pulse tube, and the auxiliary pressure switching valve. The first pulse tube flow path connects the secondary pressure switching valve to the high temperature end of the first stage pulse tube, and the second pulse tube flow path connects the secondary pulse tube flow path. connecting a pressure switching valve to the hot end of the second stage pulse tube;
During a first standby period in which the high temperature end of the first stage regenerator is not connected to either the compressor discharge port or the compressor suction port, the main pressure switching valve is configured such that the high temperature end of the first stage regenerator is connected to the an intake period in which the hot end of the first stage regenerator is connected to the compressor discharge, a second standby period in which the hot end of the first stage regenerator is not connected to either the compressor discharge or the compressor inlet, and the first stage regenerator. is configured to sequentially repeat an exhaust period in which the hot end of is connected to the compressor inlet;
The auxiliary pressure switching valve connects both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube to the compressor discharge port before 1/2 of the first standby period elapses. and both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube are connected to the compressor suction port before 1/2 of the second waiting period elapses. A multi-stage pulse tube refrigerator characterized by: 2. The multi-stage system according to claim 1, wherein said first pulse tube flow path is provided with a first flow rate adjusting element, and said second pulse tube flow path is provided with a second flow rate adjusting element. pulse tube refrigerator. 3. The multistage pulse tube refrigerator according to claim 1, wherein at least one of said main pressure switching valve and said sub pressure switching valve is detachably connected to said cold head. The pulse tube communication passage includes a pulse tube connection pipe that connects the secondary pressure switching valve to the branch portion, and the pulse tube connection pipe is attachable/detachable to each of the secondary pressure switching valve and the branch portion. 4. The multi-stage pulse tube refrigerator according to any one of claims 1 to 3, characterized by: further comprising a DC flow control flow path arranged in parallel with the secondary pressure switching valve and connecting both the hot end of the first stage pulse tube and the hot end of the second stage pulse tube to the compressor intake; 5. The multi-stage pulse tube refrigeration system according to claim 1, wherein said DC flow control flow path branches from said pulse tube communication path between said auxiliary pressure switching valve and said branch portion. machine. The coldhead includes a third stage pulse tube and a third stage regenerator having a cold end in communication with the cold end of the third stage pulse tube and connected in series with the second stage regenerator. , and
the auxiliary pressure switching valve also alternately connects the high temperature end of the third stage pulse tube to the compressor discharge port and the compressor suction port via the pulse tube communication passage;
The pulse tube communication path is further branched into a third pulse tube flow path at the branching portion, and the third pulse tube flow path connects the auxiliary pressure switching valve to the high temperature end of the third stage pulse tube. 6. The multi-stage pulse tube refrigerator according to any one of claims 1 to 5 . a first stage pulse tube;
a second stage pulse tube;
a first stage regenerator having a cold end in communication with the cold end of the first stage pulse tube;
a second stage regenerator having a cold end in communication with the cold end of the second stage pulse tube and connected in series with the first stage regenerator;
a regenerator communication passage connecting the high temperature end of the first stage regenerator to a main pressure switching valve;
a pulse tube communication passage connecting both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube to the auxiliary pressure switching valve;
The pulse tube communication passage has a branch portion between the high temperature end of the first stage pulse tube, the high temperature end of the second stage pulse tube, and the auxiliary pressure switching valve. The first pulse tube flow path connects the secondary pressure switching valve to the high temperature end of the first stage pulse tube, and the second pulse tube flow path connects the secondary pulse tube flow path. connecting a pressure switching valve to the hot end of the second stage pulse tube;
The main pressure switching valve is configured such that the high temperature end of the first stage regenerator is connected to the compressor during a first standby period in which the high temperature end of the first stage regenerator is not connected to either the compressor discharge port or the compressor suction port. an intake period when the hot end of the first stage regenerator is connected to the discharge, a second standby period when the hot end of the first stage regenerator is not connected to either the compressor discharge or the compressor inlet, and a high temperature of the first stage regenerator. configured to sequentially repeat an exhaust period with an end connected to the compressor inlet;
The auxiliary pressure switching valve connects both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube to the compressor discharge port before 1/2 of the first standby period elapses. and both the high temperature end of the first stage pulse tube and the high temperature end of the second stage pulse tube are connected to the compressor suction port before 1/2 of the second waiting period elapses. A cold head for a multistage pulse tube refrigerator, characterized in that

Images