A flow divider and a multi-stage pulse tube refrigerator equipped with a flow divider.

Abstract

The present invention provides a flow divider suitable for use in a multi-stage pulse tube refrigerator, which, when a working gas is oscillating between a first flow path, a second flow path on a unidirectional extension of the first flow path, and a third flow path intersecting the first flow path, allows the working gas from the first flow path to flow into the end of the second flow path over its entire length when the working gas from the first flow path is divided into the second and third flow paths. [Solution] The device comprises an outer cylinder 55a and a columnar body 61 inserted concentrically into the outer cylinder. The columnar body extends in one direction and has a main passage 62 that opens on one surface 61a facing a first flow path and on the other lower surface 61b facing a second flow path, and the first flow path and the second flow path communicate through this main passage. The first flow path and the third flow path communicate through a gap 63 between the columnar body and the outer cylinder. The columnar body is provided with a plurality of sub-passages 65 that are located around the opening of the main passage and open on at least the other surface of the columnar body so as to be symmetrical with respect to the hole axis of the main passage.

Description

Technical Field

[0001] When reciprocatingly flowing an operating gas between a first flow path, a second flow path connected on a one-way extension line of the first flow path, and a third flow path connected in a direction intersecting the one-way direction of the first flow path, the present invention relates to a combined flow divider that divides the operating gas from the first flow path into the second flow path and the third flow path at a predetermined flow rate ratio, and a multi-stage pulse tube refrigerator including this combined flow divider.

Background Art

[0002] As this type of multi-stage pulse tube refrigerator, for example, the one described in Patent Document 1 (see FIG. 4) is known. This one includes a pressure vibration generating means for generating pressure vibration in the operating gas, a pulse tube into which the pressure-vibrated operating gas flows, a regenerator provided between the pressure vibration generating means and the pulse tube for precooling the operating gas flowing into the pulse tube, and a buffer tank communicating with the high-temperature end of the pulse tube for controlling the phase of the pressure vibration of the operating gas to generate cold due to the expansion of the operating gas at the low-temperature end of the pulse tube. The low-temperature end of the pulse tube and the low-temperature end of the regenerator are connected via a gas passage of a cooling stage that functions as a heat exchanger, and a plurality of such cooling stages are provided. Specifically, the high-temperature end of the first-stage regenerator is connected to the compressor of the pressure vibration generating means by piping, and the low-temperature end thereof is connected to the gas passage of the first-stage cooling stage. The low-temperature end of the first-stage regenerator is connected to the high-temperature end of the second-stage regenerator, and the low-temperature end of the second-stage regenerator is connected to the gas passage of the second-stage cooling stage. At this time, the first-stage regenerator and the second-stage regenerator are arranged side by side in one direction.

[0003] In the multi-stage pulse tube refrigerator described above, the working gas (e.g., helium gas) flows as a reciprocating kinetic flow with a roughly sinusoidal pressure amplitude within a series of systems that pass through a pressure oscillation generating means, each stage's regenerator, each stage's cooling stage, and each stage's pulse tube, and leads to a phase control means. At this time, a phase difference is generated between the pressure change and the volume change of the working gas, and this constant phase difference causes cold to occur at the low-temperature end of each stage's pulse tube due to the expansion of the working gas, cooling each stage's cooling stage to an extremely low temperature (e.g., 30K for the first stage's cooling stage and 4K for the second stage's cooling stage). When the working gas is flowed in a reciprocating kinetic flow in this manner, it is necessary to divide the working gas from the first stage's regenerator into the gas passage of the first stage's cooling stage and the second stage's regenerator at a predetermined flow rate ratio. Typically, a flow divider is provided in the first stage's cooling stage, located between the low-temperature end of the first stage's regenerator and the low-temperature end of the second stage's regenerator.

[0004] As a flow divider, for example, one is used that includes a columnar body inserted into a storage space formed in the first cooling stage, with a gap between it and the inner wall surface defining the storage space. The columnar body is provided with internal passages that open to one side of the columnar body facing the cylindrical regenerator body (hereinafter referred to as the "first body") that constitutes the first regenerator, which extends in one direction (the direction in which each regenerator is arranged side by side), and to the other side of the columnar body facing the inside of the cylindrical regenerator body (hereinafter referred to as the "second body") that constitutes the second regenerator. The first body and the second body are in communication through these internal passages, and the first body is in communication with the gas passage of the first cooling stage through the gap. When a working gas flowing with pressure amplitude is divided between the gas passage of the first cooling stage and the second-stage regenerator at a predetermined flow rate ratio (e.g., 1:1), it is necessary to set the ratio of the passage cross-sectional areas of the internal passage and the gap to a predetermined range (e.g., 1:1 to 1:1.3) to approximately match the resistance to the passage of the working gas. However, considering cooling performance and other factors, the passage cross-sectional areas of the internal passage and the gap cannot be made very large. Therefore, the passage cross-sectional area of ​​the internal passage formed on the central axis of the columnar body becomes significantly smaller than the opening area on the high-temperature end side of the second body into which the working gas flows.

[0005] Here, the working gas that has passed through the internal passage of the flow divider from the first body flows into the high-temperature end of the second body with a directional component in one direction. As a result, the working gas mainly flows into the central region on the high-temperature end of the second body that is opposite the opening of the internal passage, and hardly any working gas flows into the peripheral region around the central region, which leads to a problem in that the heat exchange efficiency with the refrigerant packed in the second body is reduced. In such a case, it is conceivable to install a diffusion plate of a predetermined area between the other surface of the columnar body and the high-temperature end of the second body, causing the working gas that has passed through the internal passage to collide with the plate and diffuse in a direction intersecting the directional component. However, if a diffusion plate is installed in this way, the working gas still does not flow into the back region on the high-temperature end of the second body that is located on the opposite side of the direction in which the working gas flows into the diffusion plate, and as a result the heat exchange efficiency with the refrigerant packed in the second body is reduced. Moreover, vortices are generated in the back region of the diffusion plate, which increases the pressure loss. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-3098 [Overview of the project] [Problems that the invention aims to solve]

[0007] In view of the above, the object of the present invention is to provide a flow divider that can cause the working gas from the first flow path to flow into the end of the second flow path over its entire length, and a pulse tube refrigerator equipped with this flow divider. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a flow divider that, when causing a working gas to reciprocate between a first flow path, a second flow path connected on a unidirectional extension of the first flow path, and a third flow path connected in a direction intersecting one direction of the first flow path, divides the working gas from the first flow path into the second and third flow paths at a predetermined flow rate ratio. In a first embodiment, the present invention comprises an outer cylinder and a columnar body concentrically inserted into the outer cylinder, the columnar body extending in one direction and having main passages that open on one surface of the columnar body facing the first flow path and on the other lower surface of the columnar body facing the second flow path, the first and second flow paths communicating through these main passages, and the first and third flow paths communicating through a gap between the columnar body and the outer cylinder, and the columnar body is provided with a plurality of sub-passages that are located around the opening of the main passages and open on at least the other surface of the columnar body so as to be symmetrical with respect to the hole axis of the main passages. Furthermore, in a second embodiment, the device comprises an outer cylinder and a columnar body inserted concentrically into the outer cylinder, the columnar body extending in one direction and having main passages that open to one surface of the columnar body facing a first flow path and to the other lower surface of the columnar body facing a second flow path, the first flow path and the second flow path communicating through these main passages, the first flow path and the third flow path communicating through a gap between the columnar body and the outer cylinder, an annular passage facing a second flow path further formed between the columnar body and the outer cylinder, and the columnar body having at least one secondary passage that opens into the annular passage.

[0009] Furthermore, in order to solve the above problems, the multi-stage pulse tube refrigerator of the present invention is characterized in that it is equipped with a multi-stage cooling stage, a regenerator connected to one cooling stage, and other regenerators whose ends are connected to one cooling stage and another cooling stage, respectively, arranged in parallel in one direction, with the inside of one regenerator being designated as a first flow path, the inside of the other regenerators as a second flow path, and the gas passage of the cooling stage to which one regenerator is connected as a third flow path, and when the working gas is oscillated back and forth between the first flow path, the second flow path and the third flow path, the refrigerator is equipped with the above-mentioned flow divider to divide the working gas from the first flow path into the second flow path and the third flow path at a predetermined flow rate ratio.

[0010] According to the present invention, the working gas from one regenerator (first flow path) is divided by a flow divider into another regenerator (second flow path) and the gas passage of the cooling stage (third flow path). At this time, in addition to the working gas flowing into one end (high-temperature end) of the other regenerator from the opening of the main passage (internal passage) of the columnar body, working gas also flows in from the openings of the sub-passages surrounding the main passage or from the sub-passages via the annular passage. In other words, for example, working gas flows from the opening of the main passage formed on the central axis of the columnar body toward the central region of the high-temperature end of the regenerator, and working gas flows from the openings of each sub-passage and the annular passage toward the peripheral regions surrounding the central region. As a result, the working gas can flow throughout the high-temperature end of the other regenerator without the need to use a diffusion plate as in the conventional example described above. As a result, problems such as a decrease in heat exchange efficiency with the refrigerant filled in the other regenerator can be eliminated. In this invention, the term "flow divider" refers to a device that combines the functions of dividing the working gas from the first flow path into a second and third flow path at a predetermined flow rate ratio, and merging the working gas from the second and third flow paths in the first flow path. Furthermore, the working gas that is subjected to reciprocating motion includes a component with a unidirectional component. In addition, when a secondary passage is provided, it is necessary to set the ratio of the total cross-sectional area of ​​the main passage and the secondary passage to the cross-sectional area of ​​the gap to a predetermined range so that the resistance to the passage of the working gas is approximately equal, and the opening diameters of the main passage and the secondary passage, and the number of secondary passages are set accordingly. For example, the cross-sectional areas of the main passage and the secondary passage can be made the same, or the main passage can have a larger cross-sectional area than the secondary passage. In this case, each secondary passage can be branched from the main passage and open to one side and the other side of the columnar body, respectively.

[0011] Here, if the sub-passage is formed to extend linearly, the working gas flows from the opening of the sub-passage to the high-temperature end of the other regenerator with a directional component along the sub-passage. In this case, depending on, for example, the opening area of ​​the sub-passage and the (radial) distance between the main passage and the sub-passage, there is a risk that the working gas will not flow into the region of the second body's high-temperature end side that is opposite to the other surface of the columnar body located between the main passage and the sub-passage. Therefore, the sub-passage may be curved or bent to extend toward one surface and the other surface of the columnar body. This is advantageous because it allows the working gas from the opening of the sub-passage to spread outwards and flow into the high-temperature end of the other regenerator (i.e., the area surrounding the high-temperature end). On the other hand, a configuration can be adopted in which the main passage has funnel-shaped portions at both ends that widen toward one surface and the other surface of the columnar body. This allows the working gas from the opening of the main passage to spread outwards and flow into the high-temperature end of the other regenerator (i.e., the central region of the high-temperature end), and furthermore, it is advantageous because it reduces vortex-induced pressure loss caused by changes in diameter along the passage. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic cross-sectional view showing a multi-stage pulse tube refrigerator according to an embodiment of the present invention. [Figure 2] (a) is an enlarged cross-sectional view of the main part (flow divider) of the multi-stage pulse tube refrigerator shown in Figure 1, and (b) is a partial cross-sectional view along the line IIb-IIb in Figure 2(a). [Figure 3] A schematic cross-sectional view corresponding to Figure 2(a) of a conventional pulse tube refrigerator. [Figure 4] Enlarged cross-sectional view of a modified flow divider. [Figure 5] Enlarged cross-sectional view of a flow divider relating to another modified example. [Figure 6] Enlarged cross-sectional view of a flow divider relating to another modified example. [Figure 7] Enlarged cross-sectional view of a flow divider according to another embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, with reference to the drawings, embodiments of the current combiner / divider DP and the two-stage pulse tube refrigerator PR equipped with the current combiner / divider DP of the present invention will be described, using a so-called two-stage type as an example, with helium gas as the working gas. In the following, terms indicating directions such as up, down, left, and right will be based on Figure 1, which shows the installation position of the two-stage pulse tube refrigerator PR.

[0014] Referring to Figure 1, the two-stage pulse tube refrigerator PR of this embodiment comprises a pressure vibration generating means 1 for generating pressure vibrations in helium gas, two pulse tubes 21 and 22 into which the pressure-vibrated helium gas flows, two regenerators 31 and 32 arranged side by side in the vertical direction and provided between the pressure vibration generating means 1 and each pulse tube 21 and 22 to pre-cool the helium gas flowing into the pulse tubes 21 and 22, and a phase control means 4 having buffer tanks 41 that communicate with the high-temperature ends 2a of each pulse tube 21 and 22, respectively, for controlling the phase of the pressure vibrations of the helium gas and generating cold at the low-temperature ends 2b of each pulse tube 21 and 22 due to the expansion of the helium gas. The low-temperature end 2b of one pulse tube 21 and the low-temperature end 3b of the first-stage regenerator 31 are connected via a first-stage cooling stage 51 having a gas passage 51 that extends horizontally and perpendicularly to the vertical direction, and the low-temperature end 2b of the other pulse tube 22 and the low-temperature end 3b of the second-stage regenerator 32 are connected via a second-stage cooling stage 52 having a gas passage 51 that extends horizontally. Although not specifically illustrated and described, heat exchangers of a known structure are provided in the portions of the gas passage 51 located directly below the low-temperature end 2b of each pulse tube 21 and 22.

[0015] The first and second cooling stages 51 and 52 are made of metal with excellent thermal conductivity, such as copper or copper alloy, and are prismatic in shape. A first recess 52 communicating with the gas passage 51 is provided on the upper surface of the left end of each cooling stage 51 and 52, and a second recess 53 communicating with the gas passage 51 is provided on the upper surface of the right end of each cooling stage 51 and 52. A third recess 54 is also provided on the lower surface of the right end of the first cooling stage 51, opposite the second recess 53. The pressure vibration generating means 1 is equipped with a helium gas compressor 11, a high-pressure valve 12 is provided on the output side of the high-pressure gas of the compressor 11, and a low-pressure valve 13 is provided on the gas recovery side of the compressor 11, and the opening and closing of the high-pressure valve 12 and the low-pressure valve 13 are periodically switched by a control controller (not shown). The first piping 14 from the compressor 11 is connected to the high-temperature end 3a of the regenerator 3.

[0016] Each pulse tube 21 and 22 has the same form and includes a cylindrical pulse tube body 21. An upper heat exchanger 22 and a lower heat exchanger 23 are incorporated into the upper and lower parts of the pulse tube body 21, respectively. The upper heat exchanger 22 and the lower heat exchanger 23 have the same form and are constructed by stacking mesh members, for example, made by weaving metal wires with excellent thermal conductivity such as copper or copper alloys in a grid pattern, with gaps in the vertical direction. Known wires can be used to make up the mesh members, and the peripheral edges of each mesh member are joined to the inner surface of the pulse tube body 21 by a known method appropriately selected, such as thermal diffusion bonding. The low-temperature end 2b side of the pulse tube body 21 is then fitted in an airtight manner into a first recess 52 having a contour that matches the outer shape of the pulse tube body 21, and communicates with the gas passage 51. The buffer tank 41 of the phase control means 4 is connected to the high-temperature end 2a at the top of the pulse tube body 21 via a second pipe 42, and an orifice 43 is interposed in the second pipe 42. In addition, a bypass pipe 44 is connected to the second pipe 42, which connects the high-temperature end 2a of the pulse tube 2 and the high-temperature end 3a of the regenerator 3, and an orifice 45 is interposed in the bypass pipe 44.

[0017] Each of the first and second stage regenerators 31 and 32 has a cylindrical regenerator body 31. In this embodiment, the regenerator body 31 of the first stage regenerator 31 (hereinafter referred to as the "first body 31a") constitutes a first flow path, and the regenerator body 31 of the second stage regenerator 32 (hereinafter referred to as the "second body 31b") constitutes a second flow path connected to a unidirectional extension of the first flow path. The gas passage 51 of the first stage cooling stage 51 constitutes a third flow path. The first body 31a and the second body 31b are filled with a known refrigerant 32. Furthermore, cap bodies 33, each made by stacking multiple mesh members similar to those described above, are attached to the upper and lower end openings of the first body 31a and the second body 31b, respectively (in Figure 1, the cap bodies on the upper end opening of the first body 31a and the lower end opening of the second body 31b are not shown), to prevent the cold storage material 32 from coming out of each cold storage body 31. The lower end of the first body 31a is fitted in a second recess 53 having a contour that matches its outer shape in an airtight manner, and the upper end of the second body 31b is fitted in a third recess 54 having a contour that matches its outer shape in an airtight manner, so that the first body 31a and the second body 31b are arranged side by side in the vertical direction (one direction). Furthermore, when the helium gas flows as a reciprocating kinetic flow with a pressure amplitude in a roughly sinusoidal manner through the pressure oscillation generating means 1, each stage of regenerators 31, 32, each stage of cooling stages 51, 52, and each pulse tube 21, 22, and leads to the phase control means 4, the first stage cooling stage 51 is equipped with the flow divider DP of this embodiment in order to divide the helium gas from the first stage regenerator 31 between the gas passage 51 of the first stage cooling stage 51 and the second stage regenerator 32 at a predetermined flow rate ratio.

[0018] Referring also to FIGS. 2(a) and (b), in the first cooling stage 51, a circular storage space 55 in cross-section is formed between the second recess 53 and the third recess 54 and communicates with the second recess 53 and the third recess 54 respectively, and a combined flow divider DP is incorporated in the storage space 55. The combined flow divider DP includes a columnar body 61 having a circular cross-section. In the columnar body 61, a main passage 62 extending in the vertical direction is formed at its center line Cl (in this case, the hole axis of the main passage 62 coincides with the center line Cl). The main passage 62 opens to the upper surface 61a facing the lower end opening of the first main body 31a and the lower surface 61b facing the upper end opening of the second main body 31b respectively, and the first-stage regenerator 31 and the second-stage regenerator 32 communicate with each other through the main passage 62. Also, regarding the inner wall surface 55a of the first cooling stage 51 that defines the storage space 55 as the outer cylinder, a gap 63 is provided between the inner wall surface 55a and the outer peripheral surface of the columnar body 61, and through the gap 63, the first-stage regenerator 31 and the gas passage 51 of the first cooling stage 51 with one end opening to the inner wall surface 55a communicate with each other. A seal member 64 is provided between the inner wall surface 55a and the columnar body 61 so as to prevent the flow of helium gas between the gas passage 51 of the first cooling stage 51 and the second main body 31b. As the seal member 64, a known one having predetermined compression characteristics and capable of exhibiting sealing performance even in an extremely low temperature environment is used.

[0019] Here, FIG. 3 shows a conventional two-stage pulse tube refrigerator PR p In FIG. 3, the same components and elements as those in the above embodiment are denoted by the same reference numerals. In this device, from the first-stage regenerator 31 to the combined flow divider DP pThe helium gas that has passed through the internal passage Dp1 flows into the high-temperature end 3a of the second-stage regenerator 32 with a unidirectional component. In this case, the helium gas mainly flows into the central region of the high-temperature end 3a of the second-stage regenerator 32 that is facing the opening of the internal passage Dp1, and hardly any helium gas flows into the surrounding region around the central region. For this reason, for example, a diffusion member De is installed at the high-temperature end 3a of the second-stage regenerator 32. As a diffusion member De, for example, one that consists of a central diffusion plate De1, an annular plate De2 arranged concentrically with the diffusion plate De1, and multiple arm plates De3 connecting the diffusion plate De1 and the annular plate in the radial direction is used. By installing the diffusion member De at the opening of the internal passage Dp1 with a vertical gap and facing the diffusion plate De1, the helium gas that has passed through the internal passage Dp1 is made to collide with the diffusion member De and diffuse in the circumferential direction. However, when a diffusion member De is provided, as shown by the dashed line in Figure 3, helium gas becomes less able to flow to the back regions of the diffusion plate De1, annular plate De2, and arm plate De3 located on the high-temperature end side 3a of the second body 31b in the direction of helium gas inflow. As a result, the heat exchange efficiency with the coolant 32 filled in the second body 31b decreases. Moreover, vortices are generated in the back region of the diffusion plate, which increases pressure loss.

[0020] In this embodiment, a plurality of auxiliary passages 65 are provided in the columnar body 61, which branch from the main passage 62 and open to the upper surface 61a and the lower surface 61b of the columnar body 61, respectively. The openings of the auxiliary passages 65 are located around the opening of the main passage 62 and are symmetric about the hole axis of the main passage 62, that is, the central axis Cl (in this embodiment, eight at equal intervals of 45 degrees in the circumferential direction). Further, at both ends of the main passage 62, funnel-shaped portions 66 that expand in diameter toward the upper surface 61a and the lower surface 61b of the columnar body 61 are formed so as to reduce the pressure loss caused by vortices generated due to the change in diameter in the middle of the passage. Here, when the helium gas flowing with a pressure amplitude is divided into the gas passage 51 of the first-stage cooling stage 51 and the regenerator 32 of the second stage at a predetermined flow rate ratio (for example, 1:1), it is necessary to set the ratio of the passage cross-sectional area between the main passage 62 excluding the funnel-shaped portion 66 and the gap 63 within a predetermined range (for example, 1:1 to 1:1.3) to make the passage resistance of the helium gas substantially the same. Accordingly, the opening diameters of the main passage 62 and the auxiliary passages 65 and the number of the auxiliary passages 65 are appropriately set. For example, the passage cross-sectional areas of the main passage 62 and the auxiliary passages 65 can be made the same, or the main passage 62 can have a larger passage cross-sectional area than the auxiliary passages 65.

[0021] When the two-stage pulse tube chiller PR is in operation, first the high-pressure valve 12 is opened and the low-pressure valve 13 is closed, causing the high-pressure helium gas compressed by the compressor 11 to flow into the first stage regenerator 31 via the first piping 14. The helium gas that flows into the first stage regenerator 31 is cooled by the regenerating agent 32 installed inside the first stage regenerator 31, and as its temperature decreases, it is divided by the flow divider DP. One of the divided helium gases flows from the low-temperature end 3b of the first stage regenerator 31 into the gas passage 51 of the first stage cooling stage 51, where it is further cooled by a heat exchanger (not shown) inside and flows into the low-temperature end 2b of one of the pulse tubes 21, where it is cooled by the lower heat exchanger 23. Meanwhile, the other helium gas flows into the second-stage regenerator 32, and from the low-temperature end 3b of the second-stage regenerator 32, it flows into the gas passage 51 of the second-stage cooling stage 52, where it is further cooled in a heat exchanger (not shown) inside and flows into the low-temperature end 2b of the pulse tube 22, where it is cooled in the lower heat exchanger 23. As high-pressure helium gas flows into the low-temperature end 2b of each pulse tube 21, 22, and a portion of the high-pressure helium gas compressed by the compressor 11 flows into the second piping 42 via the orifice 45 of the bypass pipe 44, the pressure in each pulse tube 21, 22 becomes higher than that inside the buffer tank 41, and the helium gas in the pulse tube 2 flows into the buffer tank 41 through the orifice 43 of the second piping 42.

[0022] Next, when the high-pressure valve 12 is closed and the low-pressure valve 13 is opened, the helium gas in each pulse tube 21, 22 flows into the low-temperature section 3b of the first and second stage regenerators 31, 32, respectively, and passes through them. At this time, because the passing helium gas is at a low temperature, it absorbs heat from each regenerator 31, 32, and is recovered from the high-temperature end 3a of each regenerator 31, 32 via the low-pressure valve 13 to the compressor 11. As the above process is repeated, the helium gas flows as a reciprocating kinetic flow with a pressure amplitude in a roughly sinusoidal manner within a series of systems that pass through the pressure oscillation generating means 1, the regenerators 31, 32, the cooling stage 5, and the pulse tubes 21, 22, and lead to the buffer tank 41 of the phase control means 4. At this time, a phase difference occurs between the pressure change and the volume change of the helium gas. This constant phase difference causes coldness at the low-temperature end 2b of the pulse tubes 21 and 22 due to the expansion of the helium gas, and the first cooling stage 51 is cooled to an extremely low temperature of 30K, and the second cooling stage 52 is cooled to an extremely low temperature of 4K. The phase difference is adjusted by appropriately setting the volume of the buffer tank 41, which is the phase control means 4, and the orifice 43 of the second pipe 42.

[0023] According to the above embodiment, when helium gas from the first-stage regenerator 31 is divided by the flow divider DP into the second-stage regenerator 32 and the gas passage 51 of the first-stage cooling stage 51, in addition to the helium gas that has passed through the main passage 62, helium gas that has passed through the sub-passages 65 surrounding the main passage 62 flows into the high-temperature end 3a of the second-stage regenerator 32. In other words, as indicated by the arrows in Figure 2, helium gas flows from the funnel-shaped portion 66 of the main passage 62 toward the central region of the high-temperature end 3a of the second-stage regenerator 32, and helium gas flows from the openings of each sub-passage 65 toward the peripheral regions located around the central region. As a result, it becomes possible to allow helium gas to flow into the high-temperature end 3a of the second-stage regenerator 32 over its entire circumferential direction without using a diffusion member De as in the conventional example shown in Figure 3. As a result, problems such as a decrease in heat exchange efficiency with the coolant 32 filled in the second-stage regenerator 32 can be eliminated. Furthermore, because the main passage 62 has funnel-shaped portions 66 at both ends, the working gas from the opening of the main passage 62 can spread outwards and flow into the high-temperature end 3a of the second-stage regenerator 32.

[0024] Although embodiments of the present invention have been described above, various modifications are possible as long as they do not deviate from the technical concept of the present invention. In the above embodiments, a two-stage system was used as an example, but the present invention is not limited thereto, and can also be applied to a three-stage system, for example. In such a case, a third recess 54 can be provided on the lower right end of the second cooling stage 52, facing the second recess 53, and the upper end of the regenerator body (not shown) of the third regenerator can be fitted into the third recess 54 in an airtight manner. Furthermore, in the above embodiments, an example was described in which the diameter of the first body 31a of the first regenerator 31 and the second body 31b of the second regenerator 32 were made equal, but the present invention is not limited thereto, and since the environment (temperature and pressure) inside the second body 31b is different from that inside the first body 31a, the diameter of the second body 31b may be made smaller. Furthermore, although the example described was the case in which a sealing member 64 is provided between the inner wall surface 55a and the columnar body 61, the explanation is not limited to this, and a so-called flat seal may also be used as long as it can prevent the flow of helium gas between the gas passage 51 of the first cooling stage 51 and the second main body 31b.

[0025] In the above embodiment, a storage space 55 is provided in the first cooling stage 51, and its inner surface is described as an outer cylinder. However, the invention is not limited to this, and an outer cylinder can be provided separately. Furthermore, in the above embodiment, a columnar body 61 is described as having multiple sub-passages 65 branching off from the main passage 62 and opening on the upper surface 61a and lower surface 61b of the columnar body 61, respectively. However, the invention is not limited to this. For example, as shown in Figure 4, if multiple sub-passages 65 branching off from the main passage 62 and opening on the lower surface 61b of the columnar body 61 are provided in the columnar body 61, when helium gas is circulated back and forth between the first-stage regenerator 31 and the gas passage 51 of the second-stage regenerator 32 and the first-stage cooling stage 51, the helium gas from the first-stage regenerator 31 can be divided into the gas passages 51 of the second-stage regenerator 32 and the first-stage cooling stage 51 at a predetermined flow rate ratio.

[0026] Furthermore, although the above embodiment was described using a case where the sub-passage 65 is branched from the main passage 62 as an example, it is not limited to this, as long as helium gas can flow into the entire high-temperature end 3a of the second-stage regenerator 32. As shown in Figure 5, multiple sub-passages 65 extending vertically around the main passage 62 can be provided. When the sub-passage 65 is formed to extend linearly, the helium gas flows into the high-temperature end 3a of the second-stage regenerator 32 from the opening of the sub-passage 65 with a directional component along the sub-passage 65. Therefore, in order to more reliably flow helium gas into the entire high-temperature end 3a of the second-stage regenerator 32, as shown in Figure 6, the sub-passage 65 branched from the main passage 62 may be curved and extend toward one surface 61a and the other surface 61b of the columnar body 61, respectively. In this case, although not specifically illustrated and described, the sub-passage 65 can also be partially bent. As a result, the helium gas repeatedly collides on the inner surface of the sub-passage 65 as it passes through it, causing the helium gas from the opening of the sub-passage 65 to spread outwards and flow into the high-temperature end 3a of the second-stage regenerator 32. At this time, a funnel-shaped section (not shown) similar to that of the main passage 62 can also be provided in the sub-passage 65.

[0027] In the above embodiment, a columnar body 61 is provided with multiple sub-passages 65 that open to the upper surface 61a and the lower surface 61b of the columnar body 61, respectively, but the embodiment is not limited to this. In a flow divider DP according to another embodiment, as shown in Figure 7, for example, a stepped portion 610 that is recessed upward is formed on the outer peripheral edge of the lower surface of the columnar body 61, and when the flow divider DP is assembled into the storage space 55, an annular passage 7 is formed from the gap between the columnar body 61 and the upper inner surface of the second body 31b of the second regenerator 32, and leads to the second body 31b. At this time, the direct flow of helium gas between the gas passage 51 of the first cooling stage 51 and the annular passage 7 (and thus the second body 31b) is prevented by the sealing member 64. The columnar body 61 can be provided with at least one sub-passage 65 that opens to the annular passage 7. As a result, in addition to the helium gas that has passed through the main passage 62, helium gas that has passed through the annular passage 7 from the sub-passage 65 flows in, and the same effects as described above are obtained. In this case, multiple sub-passages 65 can be provided, but in this case, it is preferable to provide them symmetrically around the central axis Cl, as described above.

[0028] Furthermore, although the above embodiment described an example in which the current flow divider DP of the present invention is installed in a multi-stage pulse tube refrigerator PR, the present invention is not limited to this. The current flow divider of the present invention can be widely used in situations where, when a working gas is to be reciprocated between a first flow path, a second flow path connected on a unidirectional extension of the first flow path, and a third flow path connected in a direction intersecting one direction of the first flow path, the working gas from the first flow path is to be divided into the second and third flow paths at a predetermined flow rate ratio, and it is necessary to allow the working gas to flow over the entire end of the second flow path. [Explanation of Symbols]

[0029] DP...flow divider, PR...two-stage pulse tube refrigerator, 31...first stage regenerator (constitutes the first flow path), 32...second stage regenerator (constitutes the second flow path), 3a...high temperature end, 3b...body temperature end, 51...first stage cooling stage, 51...gas passage (constitutes the third flow path), 55a...inner surface of the first stage cooling stage (component of the outer cylinder), 61...columnar body, 61a...upper surface of the columnar body, 61b...lower surface of the columnar body, 62...main passage, 66...funnel-shaped section, 65...secondary passage, 7...annular passage.

Claims

1. A flow divider that, when causing a working gas to reciprocate between a first flow path, a second flow path connected to a unidirectional extension of the first flow path, and a third flow path connected in a direction intersecting one direction of the first flow path, divides the working gas from the first flow path into the second flow path and the third flow path at a predetermined flow ratio, The apparatus comprises an outer cylinder and a columnar body inserted concentrically into the outer cylinder, with the columnar body extending in one direction and having main passages opening on one surface of the columnar body facing a first channel and on the other lower surface of the columnar body facing a second channel, through which the first channel and the second channel communicate, and through the gap between the columnar body and the outer cylinder, the first channel and the third channel communicate. A flow divider characterized by having a columnar body comprising a plurality of sub-passages located around the opening of the main passage and opening to at least the other face of the columnar body so as to be symmetrical with respect to the hole axis of the main passage.

2. A flow divider that, when causing a working gas to reciprocate between a first flow path, a second flow path connected to a unidirectional extension of the first flow path, and a third flow path connected in a direction intersecting one direction of the first flow path, divides the working gas from the first flow path into the second flow path and the third flow path at a predetermined flow ratio, The apparatus comprises an outer cylinder and a columnar body inserted concentrically into the outer cylinder, with the columnar body extending in one direction and having main passages opening on one surface of the columnar body facing a first channel and on the other lower surface of the columnar body facing a second channel, through which the first channel and the second channel communicate, and through the gap between the columnar body and the outer cylinder, the first channel and the third channel communicate. A flow divider characterized in that an annular passage facing a second flow path is further formed between a columnar body and an outer cylinder, and the columnar body is provided with at least one sub-passage opening into the annular passage.

3. The flow divider according to claim 1, characterized in that each of the sub-passages is branched from the main passage and opens to one side and the other side of the columnar body, respectively.

4. The flow divider according to claim 2, characterized in that the sub-passage extends in a curved or bent manner toward one face and the other face of the columnar body.

5. The flow divider according to claim 1 or 2, characterized in that it has funnel-shaped portions at both ends of the main passage that widen in diameter toward one face and the other face of the columnar body.

6. In a multi-stage pulse tube chiller equipped with multiple cooling stages, in which one regenerator connected to one cooling stage and other regenerators whose ends are connected to one cooling stage and the other cooling stages respectively are arranged in parallel in one direction, A multistage pulse tube refrigerator characterized by comprising a flow divider according to any one of claims 1 to 5 for dividing the working gas from the first flow path to the second and third flow paths at a predetermined flow ratio when the working gas is oscillating back and forth between the first flow path, the second flow path, and the third flow path, with the first flow path being defined as the first flow path, the other flow path being defined as the second flow path, and the gas passage of the cooling stage to which the first flow path is connected as the third flow path.

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