JP7033009B2 - Pulse tube refrigerator - Google Patents

Description

The present invention relates to a pulse tube refrigerator.

A pulse tube refrigerator generally includes a vibration flow source, a refrigerator, a pulse tube, and a phase control mechanism as main components. There are several methods for generating oscillating flow. For example, a so-called GM (Gifford-McMahon) method using a combination of a compressor and a periodic flow path switching mechanism and a sterling method in which a vibration flow is generated by a harmonically oscillating piston are known.

Japanese Patent No. 3895516

In the GM type pulse tube refrigerator, a rotary valve is typically used as a flow path switching mechanism. The rotary valve has a valve stator and a valve rotor in surface contact with the valve stator, and a plurality of working gas flow paths are formed on the contact surface. When the valve rotor rotates and slides with respect to the valve stator, the connection between the working gas flow paths is switched, which enables the flow path switching for the proper operation of the pulse tube refrigerator.

In order to improve the refrigerating performance of the pulse tube refrigerator, it is desired to reduce the pressure loss generated in the working gas in the working gas flow path of the rotary valve. One measure is to make each individual working gas flow path wider, but such expansion of the flow path can result in an increase in the area of the rotating sliding surface of the valve rotor. As the rotating sliding surface becomes larger, the frictional resistance acting on the rotating valve rotor also increases. Then, the torque required to drive the valve rotor also increases, which leads to an increase in the size of a drive source such as a motor for driving the rotary valve. Such disadvantages can be significant in large pulse tube refrigerators.

One of the exemplary objects of an aspect of the present invention is to suppress the increase in size of the drive source of the flow path switching mechanism for a pulse tube refrigerator.

According to an aspect of the present invention, the pulse tube refrigerator comprises a pulse tube and a cold storage device, the cold head in which the low temperature end of the pulse tube is connected to the low temperature end of the cold storage device, a valve drive chamber, and the valve. A spool that moves between a first position and a second position according to the pressure of the drive chamber is provided, and the spool connects the high temperature end of the regenerator to the compressor discharge port at the first position, and the first position. It includes a spool valve that connects the high temperature end of the cold storage to the compressor suction port at two positions, and a pressure control mechanism that is arranged away from the cold head and controls the pressure in the valve drive chamber.

It should be noted that any combination of the above components or components or expressions of the present invention that are mutually replaced between methods, devices, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to suppress an increase in the size of the drive source of the flow path switching mechanism for the pulse tube refrigerator.

It is a figure which shows schematic the whole structure of the pulse tube refrigerator which concerns on 1st Embodiment. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator shown in FIG. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator shown in FIG. It is a figure which shows roughly the structure of the pressure control mechanism which concerns on embodiment. It is a figure which shows schematic the whole structure of the pulse tube refrigerator which concerns on 2nd Embodiment. It is a figure which shows roughly the other configuration of the pulse tube refrigerator which concerns on 2nd Embodiment. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator which concerns on 3rd Embodiment. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator which concerns on 3rd Embodiment. It is a figure which shows roughly the other configuration of the pulse tube refrigerator which concerns on 3rd Embodiment. It is a figure which shows roughly the other configuration of the pulse tube refrigerator which concerns on 3rd Embodiment. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator which concerns on 4th Embodiment. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator which concerns on 4th Embodiment. It is a figure which shows generally the other structure of the spool valve applicable to the pulse tube refrigerator according to 4th Embodiment. It is a figure which shows roughly the other configuration of the pulse tube refrigerator which concerns on 4th Embodiment. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator which concerns on 5th Embodiment. It is a schematic diagram which shows the working gas circuit composition of the pulse tube refrigerator which concerns on 5th Embodiment. It is a figure which shows roughly the other configuration of the pressure control mechanism applicable to the pulse tube refrigerator according to the embodiment. It is a figure which shows roughly the other configuration of the pressure control mechanism applicable to the pulse tube refrigerator according to the embodiment. It is a figure which shows roughly the other configuration of the pressure control mechanism applicable to the pulse tube refrigerator according to the embodiment.

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 designated by the same reference numerals, and duplicate description will be omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience of explanation and are not limitedly interpreted unless otherwise specified. The embodiments are exemplary and do not limit the scope of the invention in any way. Not all features and combinations thereof described in the embodiments are essential to the invention.

FIG. 1 is a diagram schematically showing the overall configuration of the pulse tube refrigerator 10 according to the first embodiment. 2 and 3 are schematic views showing a working gas circuit configuration of the pulse tube refrigerator 10 shown in FIG. 1. FIG. 2 shows an intake process of the pulse tube refrigerator 10, and FIG. 3 shows an exhaust process of the pulse tube refrigerator 10.

The pulse tube refrigerator 10 includes a compressor 12 and a cold head 14. The cold head 14 includes a pulse tube 16, a regenerator 18, a cooling stage 20 for cooling the object to be cooled 19, a flange portion 22, and a room temperature portion 24. The pulse tube refrigerator 10 is a single-stage pulse tube refrigerator. However, the pulse tube refrigerator 10 can also be a multi-stage (for example, two-stage) pulse tube refrigerator.

The pulse tube refrigerator 10 is, for example, a GM (Gifford-McMahon) type double inlet type pulse tube refrigerator. Therefore, a buffer volume 26, for example, a buffer tank is connected to the room temperature portion 24 of the cold head 14. Further, the room temperature section 24 has two flow path resistances (for example, an orifice or a throttle valve). Hereinafter, for convenience of explanation, the first flow path resistance is referred to as a double inlet orifice 28, and the second flow path resistance is referred to as a buffer orifice 30. However, it is not intended to limit the flow path resistance to the orifice only.

As will be described in detail later, the pulse tube refrigerator 10 is different from a typical pulse tube refrigerator in terms of the flow path switching mechanism housed in the room temperature section 24. The room temperature section 24 includes a spool valve 32 instead of a rotary valve. The spool valve 32 includes a valve drive chamber 34 and a spool 36 that moves between a first position and a second position according to the pressure of the valve drive chamber 34. The spool 36 connects the high temperature end of the regenerator 18 to the discharge port of the compressor 12 at the first position, and connects the high temperature end of the regenerator 18 to the suction port of the compressor 12 at the second position. Further, the pulse tube refrigerator 10 is arranged away from the cold head 14 and includes a pressure control mechanism 38 that controls the pressure in the valve drive chamber 34. The pressure control mechanism 38 has a drive chamber intake valve V1 and a drive chamber exhaust valve V2.

The compressor 12 and the spool valve 32 constitute a vibration flow generation source for the pulse tube refrigerator 10. That is, from the steady flow of the working gas generated by the compressor 12, the pressure vibration of the working gas can be generated in the pulse tube 16 through the cool storage 18 by the switching operation of the spool valve 32. Further, the buffer volume 26, the double inlet orifice 28, and the buffer orifice 30 constitute a phase control mechanism for the pulse tube refrigerator 10. The phase control mechanism can delay the phase of the displacement vibration of the gas element (also called a gas piston) in the pulse tube 16 with respect to the pressure vibration of the working gas. Appropriate phase lag can cause PV work at the cold end of the pulse tube 16 to cool the working gas. The cooling stage 20 is cooled by heat exchange with the cooled working gas.

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 to the pulse tube 16 through the cool storage device 18, and the working gas is recovered from the pulse tube 16 to the compressor suction port 12b through the cold storage device 18. The compressor discharge port 12a and the compressor suction port 12b function as a high-pressure source and a low-pressure source of the pulse tube refrigerator 10, respectively. The working gas is also referred to as a refrigerant gas, for example, helium gas.

Generally, both the high pressure PH and the low pressure PL are considerably higher than the ambient environmental pressure (for example, atmospheric pressure) of the pulse tube refrigerator 10. Therefore, the high voltage PH and the low voltage PL can also be referred to as a first high voltage and a second high voltage, respectively. Usually, the high pressure PH is, for example, 2 to 3 MPa. The low pressure PL is, for example, 0.5 to 1.5 MPa.

The pulse tube refrigerator 10 is provided with a high pressure line 13a and a low pressure line 13b. The high pressure line 13a extends from the compressor discharge port 12a, branches at the high pressure line branch point 40a, and is connected to the high pressure port 42 of the cold head 14 and the drive chamber intake valve V1 of the pressure control mechanism 38. The working gas of the high pressure PH flows from the compressor 12 to the cold head 14 and from the compressor 12 to the pressure control mechanism 38 through the high pressure line 13a. The low pressure line 13b extends from the compressor suction port 12b, branches at the low pressure line branch point 40b, and is connected to the low pressure port 44 of the cold head 14 and the drive chamber exhaust valve V2 of the pressure control mechanism 38. The working gas of the low pressure PL flows from the cold head 14 to the compressor 12 and from the pressure control mechanism 38 to the compressor 12 through the low pressure line 13b.

Further, the pulse tube refrigerator 10 is provided with a valve drive chamber line 46. The valve drive chamber line 46 extends from the valve drive chamber 34, branches in the middle, and is connected to the drive chamber intake valve V1 and the drive chamber exhaust valve V2.

The high pressure line 13a and the low pressure line 13b may be rigid or flexible pipes connecting the compressor 12, the cold head 14, and the pressure control mechanism 38, respectively. Further, the valve drive chamber line 46 may be a rigid or flexible pipe connecting the cold head 14 and the pressure control mechanism 38.

The pulse tube 16 has a pulse tube high temperature end 16a and a pulse tube low temperature end 16b, and extends from the pulse tube high temperature end 16a to the pulse tube low temperature end 16b. The high temperature end 16a of the pulse tube and the low temperature end 16b of the pulse tube can also be referred to as the first end and the second end of the pulse tube 16, respectively. A rectifier may be provided at each of the pulse tube high temperature end 16a and the pulse tube low temperature end 16b. Similarly, the cold storage device 18 has a cold storage device high temperature end 18a and a cold storage device low temperature end 18b, and extends from the cold storage device high temperature end 18a to the cold storage device low temperature end 18b. The cold storage device high temperature end 18a and the cold storage device low temperature end 18b can also be referred to as the first end and the second end of the cold storage device 18, respectively. The direction in which the pulse tube 16 and the regenerator 18 extend is referred to as the axial direction A of the cold head 14.

The low temperature end 16b of the pulse tube and the low temperature end 18b of the cooler are structurally connected by a cooling stage 20 and thermally coupled. A cooling stage flow path 21 is formed in the cooling stage 20. Through the cooling stage flow path 21, the low temperature end 16b of the pulse tube fluidly communicates with the low temperature end 18b of the cool storage device. Therefore, the working gas supplied from the compressor 12 can flow from the cold storage device low temperature end 18b to the pulse tube low temperature end 16b through the cooling stage flow path 21. The return gas from the pulse tube 16 can flow from the low temperature end 16b of the pulse tube to the low temperature end 18b of the cool storage through the cooling stage flow path 21.

In the exemplary configuration, the pulse tube 16 is a cylindrical tube with a hollow inside, and the cold storage 18 is a cylindrical tube whose inside is filled with a cold storage material, both of which are adjacent to each other and are in the center of each. The axes are arranged in parallel. The pulse tube 16 and the regenerator 18 extend in the same direction from the cooling stage 20, and the pulse tube high temperature end 16a and the regenerator high temperature end 18a are arranged on the same side with respect to the cooling stage 20. In this way, the pulse tube 16, the regenerator 18, and the cooling stage 20 are arranged in a U shape.

The object to be cooled 19 is installed directly on the cooling stage 20 or is thermally coupled to the cooling stage 20 via a rigid or flexible heat transfer member. The pulse tube refrigerator 10 can cool the object to be cooled 19 by conduction cooling from the cooling stage 20. The object to be cooled 19 cooled by the pulse tube refrigerator 10 is, for example, a solid substance such as a superconducting electric magnet or other superconducting device, an infrared image pickup element or another sensor, but is not limited thereto. Needless to say, the pulse tube refrigerator 10 can also cool the gas or liquid in contact with the cooling stage 20.

On the other hand, the high temperature end 16a of the pulse tube and the high temperature end 18a of the cooler are connected by the flange portion 22. The flange portion 22 is attached to a support portion 48 such as a support base or a support wall on which the pulse tube refrigerator 10 is installed. The support 48 may be a wall material or other part of a heat insulating container or vacuum container that houses the cooling stage 20 and the object to be cooled 19 (along with the cool storage 18 and the pulse tube 16).

A pulse tube 16 and a regenerator 18 extend from one main surface of the flange portion 22 to the cooling stage 20, and a room temperature portion 24 is provided on the other main surface of the flange portion 22. Therefore, when the support portion 48 constitutes a part of the heat insulating container or the vacuum container, when the flange portion 22 is attached to the support portion 48, the pulse tube 16, the regenerator 18, and the cooling stage 20 are inside the container. The room temperature portion 24 is arranged outside the container.

In this way, the compressor 12, the room temperature section 24, and the pressure control mechanism 38 are arranged in an ambient environment (for example, a room temperature atmospheric pressure environment). The buffer volume 26 is also arranged in the surrounding environment. The cold storage 18, the pulse tube 16, and the cooling stage 20 are arranged in an environment isolated from the surrounding environment (for example, an extremely low temperature vacuum environment).

The room temperature portion 24 does not need to be directly attached to the flange portion 22. The room temperature section 24 may be disposed separately from the cold head 14 of the pulse tube refrigerator 10 and may be connected to the cold head 14 by a rigid or flexible pipe. In this way, the phase control mechanism of the pulse tube refrigerator 10 may be arranged separately from the cold head 14.

The room temperature section 24 bypasses the cooler flow path 50 that connects the spool valve 32 to the cooler 18, the buffer flow path 52 that connects the buffer volume 26 to the pulse pipe 16, and the cooling stage flow path 21, and the cooler 18 Has a bypass flow path 54 for connecting the pulse tube 16. The buffer volume 26 acts as an intermediate pressure source for the working gas having an intermediate pressure between the high pressure PH and the low pressure PL (for example, the average pressure between the high pressure PH and the low pressure PL).

The regenerator flow path 50 and the buffer flow path 52 each penetrate the flange portion 22 and extend to the regenerator high temperature end 18a and the pulse tube high temperature end 16a. The cold storage flow path 50 connects the second gas chamber 35 of the spool valve 32 to the cold storage high temperature end 18a. The double inlet orifice 28 is provided in the middle of the bypass flow path 54, and the buffer orifice 30 is provided in the middle of the buffer flow path 52. The buffer flow path 52 connects the buffer volume 26 to the buffer orifice 30 and further connects the buffer orifice 30 to the pulse tube high temperature end 16a. The bypass flow path 54 branches from the cold storage flow path 50 and is connected to the double inlet orifice 28, and further extends from the double inlet orifice 28 and joins the buffer flow path 52. The bypass flow path 54 is connected to the buffer flow path 52 between the buffer orifice 30 and the pulse tube high temperature end 16a.

Therefore, the working gas can flow in and out between the spool valve 32 and the cold storage high temperature end 18a through the cold storage flow path 50, and further, the cold storage 18 and the pulse tube low temperature end 16b can be passed through the cooling stage flow path 21. The inflow and outflow of working gas is possible between. Further, the working gas can flow in and out between the buffer volume 26 and the high temperature end 16a of the pulse tube through the buffer flow path 52, that is, the buffer orifice 30. The inflow and outflow of working gas is possible between the spool valve 32 and the high temperature end 16a of the pulse tube through the bypass flow path 54, that is, the double inlet orifice 28.

The spool valve 32 has a sleeve 56 that accommodates the spool 36 and guides the movement of the spool 36. The valve drive chamber 34 is formed between one end of the spool 36 and the sleeve 56. The valve drive chamber 34 can also be referred to as a first gas chamber of the spool valve 32. The second gas chamber 35 is formed between the other end of the spool 36 and the sleeve 56. The valve drive chamber 34 and the second gas chamber 35 are located on opposite sides of the spool 36.

The spool 36 can move with respect to the sleeve 56 due to the pressure difference between the valve drive chamber 34 and the second gas chamber 35. When the valve drive chamber 34 has a lower pressure than the second gas chamber 35, the spool 36 moves in the sleeve 56 so as to reduce the valve drive chamber 34 and expand the second gas chamber 35 (moves upward in the figure). .. On the contrary, when the valve drive chamber 34 has a higher pressure than the second gas chamber 35, the spool 36 moves in the sleeve 56 so as to expand the valve drive chamber 34 and reduce the second gas chamber 35 (downward in the figure). Move to).

The sleeve 56 has two through holes that act as a high pressure port 42 and a low pressure port 44. Further, the sleeve 56 is provided with two other through holes, through which the valve drive chamber 34 communicates with the valve drive chamber line 46 and the second gas chamber 35 communicates with the cooler 18 and the pulse tube 16 through the other. Communicate.

As an example, the spool 36 is a cylindrical member extending in the axial direction A of the cold head 14, and the sleeve 56 is a cylindrical member extending in the axial direction A of the cold head 14 and coaxially arranged with the spool 36. It is a member having an inner peripheral surface. The spool 36 and sleeve 56 can also be referred to as pistons and cylinders, respectively. The high pressure port 42 and the low pressure port 44 are formed on the side surface of the sleeve 56, and two other through holes are formed on the end face of the sleeve 56, respectively. The extending direction of the spool 36 and the sleeve 56 is not limited to the axial direction A of the cold head 14, and may be another direction.

Further, the spool valve 32 has a plurality of sealing members arranged in a clearance between the spool 36 and the sleeve 56, specifically, a first sealing member 58a, a second sealing member 58b, a third sealing member 58c, and a third sealing member 58c. It has a fourth seal member 58d. These sealing members are mounted on the spool 36 at different axial positions from each other and extend in the circumferential direction of the spool 36. The sealing member is a member that seals a working gas such as a slipper seal or an O-ring, but may be another contact seal or non-contact seal as long as it has the desired sealing performance.

The working gas space inside the spool valve 32 is separated into five sections including the valve drive chamber 34 and the second gas chamber 35 by a sealing member. The remaining three compartments are formed in the clearance between the spool 36 and the sleeve 56. That is, the clearance is separated into a first clearance region 60a, a second clearance region 60b, and a third clearance region 60c, which are adjacent to each other in the axial direction of the spool 36.

The first seal member 58a is arranged between the valve drive chamber 34 and the first clearance region 60a and is configured to prevent or minimize the direct flow of working gas between them. The second seal member 58b is arranged between the first clearance region 60a and the second clearance region 60b and is configured to prevent or minimize the direct flow of working gas between them. The third seal member 58c is arranged between the second clearance region 60b and the third clearance region 60c and is configured to prevent or minimize the direct flow of working gas between them. The fourth seal member 58d is arranged between the third clearance region 60c and the second gas chamber 35 and is configured to prevent or minimize the direct flow of working gas between them.

The spool 36 has a spool main flow path 62. One end of the spool main flow path 62 communicates with the second clearance region 60b, and the other end of the spool main flow path 62 communicates with the second gas chamber 35. The spool main flow path 62 may be formed so as to penetrate the spool 36 from the side surface to the end surface of the spool 36.

Further, a return spring 64 is provided between the spool 36 and the sleeve 56. The return spring 64 urges the spool 36 to, for example, an initial position between the top dead center and the bottom dead center of the spool 36. The return spring 64 can pull the spool 36 downward when the spool 36 is at top dead center, and pull the spool 36 upward when the spool 36 is at bottom dead center. The return spring 64 is housed in the second gas chamber 35. The return spring 64 may be provided in the valve drive chamber 34. Further, it is not essential to provide the return spring 64, and the spool valve 32 may not be provided with the return spring 64.

The spool valve 32 is fixed to the cold head 14 so as to be arranged adjacent to the cold storage high temperature end 18a. By doing so, the length of the cold storage flow path 50 can be shortened. The length of the cool storage flow path 50 may be shorter than the length of the buffer flow path 52 or the length of the bypass flow path 54. As an example, the sleeve 56 of the spool valve 32 is fixed to the flange portion 22, and the second gas chamber 35 is arranged directly above the cold storage high temperature end 18a. By doing so, the length of the cold storage flow path 50 can be shortened as much as possible.

The spool main flow path 62, the second gas chamber 35, and the refrigerator flow path 50 form a so-called dead volume that does not contribute to the refrigerating capacity of the pulse tube refrigerator 10. Therefore, the dead volume can be reduced by shortening the length of the cold storage flow path 50. This helps to improve the refrigerating capacity of the pulse tube refrigerator 10.

The operation of the spool valve 32 will be described with reference to FIGS. 2 and 3. As described above, FIG. 2 shows the state of the intake process of the pulse tube refrigerator 10, and FIG. 3 shows the state of the exhaust process of the pulse tube refrigerator 10. The spool 36 of the spool valve 32 moves to the first position in the intake process and moves to the second position in the exhaust process. The first position and the second position can also be referred to as an intake position and an exhaust position, respectively.

As shown in FIG. 2, in the intake process, the drive chamber exhaust valve V2 is opened and the drive chamber intake valve V1 is closed. The compressor suction port 12b is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a low pressure PL. At this time, the second gas chamber 35 has a pressure slightly higher than that of the low pressure PL. This is because the pressure fluctuations in the cold head 14 (ie, the regenerator 18 and the pulse tube 16) are somewhat delayed with respect to the pressure fluctuations in the valve drive chamber 34. At the start of the intake process, the spool 36 is located at or near bottom dead center (indicated by a dashed line in the second gas chamber 35 in FIG. 2). Due to the pressure difference between the valve drive chamber 34 and the second gas chamber 35, the spool 36 moves axially in the sleeve 56 so as to shrink the valve drive chamber 34 (indicated by the broken line arrow). The restoring force of the return spring 64 also helps to move the spool 36 upward.

When the spool 36 reaches the first position, that is, at or near the top dead center due to the upward movement of the spool 36, the second clearance region 60b is adjacent to the high pressure port 42. The high-pressure port 42 is connected to the second gas chamber 35 through the spool main flow path 62, and the working gas of the high-pressure PH is supplied to the cooler 18 and the pulse tube 16 from the compressor discharge port 12a. At this time, the third clearance region 60c is adjacent to the low pressure port 44. Since the low pressure port 44 is blocked by the spool 36, the connection between the cool storage 18 and the pulse tube 16 and the compressor suction port 12b is cut off.

As shown in FIG. 3, in the exhaust process, the drive chamber intake valve V1 is opened and the drive chamber exhaust valve V2 is closed. The compressor discharge port 12a is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a high pressure PH. At this time, the second gas chamber 35 has a pressure slightly lower than the high pressure PH. At the start of the exhaust process, the spool 36 is located at or near top dead center (indicated by the dashed line in the valve drive chamber 34 in FIG. 2). Due to the pressure difference between the valve drive chamber 34 and the second gas chamber 35, the spool 36 moves axially in the sleeve 56 so as to expand the valve drive chamber 34 (indicated by the broken line arrow). The restoring force of the return spring 64 also helps the spool 36 to move downward.

When the spool 36 reaches the second position, that is, at or near the bottom dead center due to the downward movement of the spool 36, the second clearance region 60b is adjacent to the low pressure port 44. The low pressure port 44 is connected to the second gas chamber 35 through the spool main flow path 62, the working gas is discharged to the compressor suction port 12b, and the pulse tube 16 and the cooler 18 become low pressure PL. At this time, the first clearance region 60a is adjacent to the high pressure port 42. Since the high pressure port 42 is blocked by the spool 36, the connection between the cool storage 18 and the pulse tube 16 and the compressor discharge port 12a is cut off.

In this way, the spool valve 32 functions as a main pressure switching valve of the pulse tube refrigerator 10 in which the compressor discharge port 12a and the compressor suction port 12b are alternately connected to the cold storage high temperature end 18a. The pressure control mechanism 38 alternately connects the compressor discharge port 12a and the compressor suction port 12b to the valve drive chamber 34 of the spool valve 32, and controls the pressure in the valve drive chamber 34 so as to appropriately drive the spool 36. be able to.

As described above, a typical pulse tube refrigerator has a rotary valve as a flow path switching mechanism, and some working gas ports are provided on the rotating sliding surface of the rotary valve. In order to switch the interconnection between these working gas ports by rotation, these ports are arranged at different locations in the radial direction on the rotating sliding surface. In order to reduce the pressure loss generated in the working gas in the rotary valve, it is necessary to widen the port, which leads to an increase in the diameter of the rotary valve, that is, an increase in the area of the rotating sliding surface. The larger the rotating sliding surface, the larger the frictional resistance that acts during rotation, so the torque required to drive the rotary valve also increases, and a large drive source such as a motor is required. This brings about disadvantages such as an increase in the manufacturing cost of the rotary valve and an increase in the size of the pulse tube refrigerator. In particular, such a disadvantage can be remarkable for a large pulse tube refrigerator that outputs a large refrigerating capacity.

In general, the pulse tube refrigerator can be operated quieter than other typical cryogenic refrigerators such as the GM refrigerator, and is therefore suitable for cooling applications that dislike noise and vibration. A rotary valve is often configured with a motor, valve rotor, and valve stator as a single rotary valve unit. If this is installed directly on the cold head of the pulse tube refrigerator, the motor will also form part of the cold head. If such a design is adopted for a large pulse tube refrigerator, a large motor will be installed directly on the cold head. Large motors are not preferred as they are a source of reasonable electromagnetic noise and / or mechanical vibration.

In order to avoid the transmission of such noise and vibration, it is conceivable to arrange the rotary valve unit in a place away from the cold head and connect the two with a long pipe. However, in this design, the piping volume from the working gas inlet / outlet of the rotary valve to the cold head cooler is also large. Since this volume is a dead volume that does not contribute to the refrigerating capacity, its increase is not desired.

In this way, in the existing pulse tube refrigerator that uses a rotary valve as the flow path switching mechanism, noise and vibration transmitted from the rotary valve to the cold head are sufficiently reduced, and an increase in dead volume and a decrease in refrigerating capacity are avoided. It is difficult to achieve without it.

On the other hand, the pulse tube refrigerator 10 according to the embodiment includes a spool valve 32. Therefore, the disadvantage caused by the rotary valve as described above is unlikely to occur.

In the spool valve 32, even if the internal flow path of the valve such as the spool main flow path 62 is expanded, it is not directly related to the increase in size of the drive source. The spool valve 32 operates fluidly by the working gas pressure of the valve drive chamber 34. Therefore, the volume of the valve drive chamber 34 may be relatively small. Therefore, the internal flow path of the spool valve 32 can be expanded while keeping the size of the valve drive chamber 34 small, whereby the pressure loss generated in the working gas in the spool valve 32 can be reduced. Compared with the case of adopting a rotary valve, it is possible to suppress an increase in the size of the drive source of the flow path switching mechanism for the pulse tube refrigerator 10.

Further, the pressure control mechanism 38 is arranged away from the cold head 14. Therefore, even if the pressure control mechanism 38 can be a noise source or a vibration source, the transmission of noise or vibration from the pressure control mechanism 38 to the cold head 14 is suppressed. In addition, since the volume of the valve drive chamber 34 may be small, the pressure control mechanism 38 may also be relatively small. Therefore, the noise or vibration that can be generated by the pressure control mechanism 38 is small in the first place, and the influence that can be exerted on the cold head 14 is also small.

As described above, the spool valve 32 is fixed to the cold head 14 so as to be arranged adjacent to the cold storage high temperature end 18a. Therefore, the refrigerating flow path 50, which has a dead volume, can be shortened, and the refrigerating capacity of the pulse tube refrigerator 10 is improved.

There may be various specific configurations of the pressure control mechanism 38. For example, the drive chamber intake valve V1 and the drive chamber exhaust valve V2 may each take the form of individually controllable valves. Each valve (V1, V2) may be an electromagnetic on-off valve. Each valve (V1, V2) may be configured to automatically open and close at a predetermined valve timing. Alternatively, the pressure control mechanism 38 may be configured in the form of a rotary valve.

FIG. 4 is a diagram schematically showing the configuration of the pressure control mechanism 38 according to the embodiment. The pressure control mechanism 38 includes a rotary valve 66 that alternately connects the compressor discharge port 12a and the compressor suction port 12b to the valve drive chamber 34.

The rotary valve 66 includes a motor 66a, a valve rotor 66b, a valve stator 66c, and a valve housing 66d. The valve rotor 66b and the valve stator 66c are housed in the valve housing 66d, and both are arranged adjacent to each other so as to be in surface contact with each other on the valve sliding surface 66e. The valve stator 66c is fixed to the valve housing 66d. The motor 66a is installed outside the valve housing 66d, and the output shaft of the motor 66a extends through the valve housing 66d to the valve rotor 66b.

A pressure chamber 66f is formed inside the valve housing 66d, and the valve rotor 66b and the valve stator 66c are arranged in the pressure chamber 66f. As an example, a high voltage line 13a is connected to the pressure chamber 66f, and a high voltage PH is introduced. A low pressure line 13b and a valve drive chamber line 46 are connected to the valve stator 66c. At least two seal members are mounted between the valve stator 66c and the valve housing 66d, one seal member seals the low pressure line 13b from the pressure chamber 66f (ie, the high pressure line 13a), and the other seal member seals the valve. The drive chamber line 46 is sealed from the low pressure line 13b. Therefore, the direct flow of working gas between the high pressure line 13a, the low pressure line 13b, and the valve drive chamber line 46 inside the rotary valve 66 is prevented.

The output shaft is rotated by the drive of the motor 66a, whereby the valve rotor 66b is rotationally slid with respect to the valve stator 66c. As the valve rotor 66b rotates and slides, the flow path connection is periodically switched on the valve sliding surface 66e, and the rotary valve 66 alternately connects the high pressure line 13a and the low pressure line 13b to the valve drive chamber line 46.

As the specific flow path configuration of the rotary valve 66 including the valve rotor 66b and the valve stator 66c, various known ones can be appropriately adopted, and thus detailed description thereof will be omitted. In the above description, the high pressure line 13a is connected to the pressure chamber 66f and the low pressure line 13b is connected to the valve stator 66c, but conversely, the high pressure line 13a is connected to the valve stator 66c and the pressure chamber 66f is connected. It is also possible to connect the low voltage line 13b to the low voltage line 13b.

As described above, when the pressure control mechanism 38 is configured as the rotary valve 66, the existing design of the rotary valve of the ultra-low temperature refrigerator can be diverted. Therefore, the pressure control mechanism 38 can be easily manufactured, which is advantageous.

FIG. 5 is a diagram schematically showing the overall configuration of the pulse tube refrigerator 10 according to the second embodiment. The pulse tube refrigerator 10 according to the second embodiment is different from the pulse tube refrigerator 10 according to the first embodiment in terms of piping connection of the working gas circuit, and the rest is described in the first embodiment. It has the same configuration as the pulse tube refrigerator 10. Hereinafter, the pulse tube refrigerator 10 according to the second embodiment will be mainly described with a configuration different from that of the first embodiment, and the common configuration will be briefly described or omitted.

The spool valve 32 is also used in the pulse tube refrigerator 10 according to the second embodiment. Therefore, similarly to the pulse tube refrigerator 10 according to the first embodiment, the pressure loss generated in the working gas in the spool valve 32 is reduced, and the flow path switching mechanism for the pulse tube refrigerator 10 is driven. It is possible to suppress the increase in size of the source at the same time. Therefore, it is advantageous as compared with the existing typical pulse tube refrigerator that employs a rotary valve as a flow path switching mechanism for the cold head.

As shown in FIG. 5, the pulse tube refrigerator 10 includes a removable joint 68 that connects the valve drive chamber 34 to the pressure control mechanism 38. The removable joint 68 is provided in the middle of the valve drive chamber line 46. The removable joint 68 is, for example, a self-sealing coupling.

The removable joint 68 may be connected to the pressure control mechanism 38 with a relatively long pipe. For example, the removable joint 68 may be installed in the valve drive chamber line 46 in the vicinity of the room temperature portion 24 of the cold head 14. In this case, the removable joint 68 is connected to the pressure control mechanism 38 by the compressor side pipe 46a, and is connected to the room temperature portion 24 (specifically, the valve drive chamber 34 of the spool valve 32) by the cold head side pipe 46b. ing. The compressor side pipe 46a is longer than the flow path length (including the cold head side pipe 46b) from the removable joint 68 to the valve drive chamber 34. Alternatively, the removable joint 68 may be installed adjacent to the room temperature portion 24.

In this way, since the pressure control mechanism 38 is connected to the cold head 14 via the removable joint 68, the valve drive chamber line 46 is lengthened and the pressure control mechanism 38 is arranged remotely from the cold head 14. Will be easy. This helps to suppress the transmission of electromagnetic noise and / or mechanical vibrations that may occur in the pressure control mechanism 38 to the cold head 14. Further, since the pressure control mechanism 38 is detachably connected to the cold head 14 by a removable joint 68, the operator can remove the pressure control mechanism 38 from the cold head 14 for maintenance.

Further, by using the relatively long compressor side pipe 46a, the spool valve 32 can be arranged close to the cold head 14 while lengthening the valve drive chamber line 46. For example, the spool valve 32 can be arranged adjacent to the cold storage high temperature end 18a. By doing so, it is possible to shorten the cold storage flow path 50 to reduce the dead volume and suppress the transmission of noise and vibration from the pressure control mechanism 38 to the cold head 14.

The removable joint 68 may be additionally provided at another location in the working gas circuit of the pulse tube refrigerator 10. As shown in FIG. 5, for example, a removable joint 68 may be provided on at least one of the high pressure line 13a and the low pressure line 13b. By doing so, it is possible to suppress the transmission of noise and vibration from the compressor 12 to the cold head 14.

Further, the pulse tube refrigerator 10 may include a manifold 70 having a high pressure line branch point 40a and a low pressure line branch point 40b. The compressor 12 and the cold head 14 are connected to each other via the manifold 70, and the compressor 12 and the pressure control mechanism 38 are connected to each other. The manifold 70 may be fixed to a floor surface or other stationary portion. The compressor 12 is located away from the manifold 70 and is connected by piping. By doing so, it is possible to suppress the transmission of noise and vibration from the compressor 12 to the cold head 14.

As shown in FIG. 5, the pressure control mechanism 38 may be located away from the manifold 70 and connected by piping. Alternatively, the pressure control mechanism 38 may be installed in the manifold 70.

FIG. 6 is a diagram schematically showing another configuration of the pulse tube refrigerator 10 according to the second embodiment. The pulse tube refrigerator 10 may include a noise blocking structure 72 installed in at least one of a high pressure line 13a, a low pressure line 13b, and a valve drive chamber line 46. The noise cutoff structure 72 is connected directly to the removable joint 68 or through a pipe, and is configured to cut off or reduce the electromagnetic noise transmitted through the pipe in which the noise cutoff structure 72 is installed. The removable joint 68 is provided on at least one side (both sides in FIG. 6) of the noise blocking structure 72.

As an example, the noise blocking structure 72 includes a pair of flanges 72a and a noise blocking body 72b sandwiched between the flanges 72a. The noise barrier 72b is a metal body coated with an insulating coating material such as a ceramic coating or a fluororesin coating. The flange 72a and the noise blocking body 72b are fixed to each other by appropriate fasteners such as bolts and nuts. A working gas flow path is formed through the flange 72a and the noise blocking body 72b.

By providing the noise blocking structure 72, it is possible to further suppress the transmission of noise from the compressor 12 or the pressure control mechanism 38 to the cold head 14.

7 and 8 are schematic views showing a working gas circuit configuration of the pulse tube refrigerator 10 according to the third embodiment. FIG. 7 shows an intake process of the pulse tube refrigerator 10, and FIG. 8 shows an exhaust process of the pulse tube refrigerator 10. The pulse tube refrigerator 10 according to the third embodiment is different from the pulse tube refrigerator 10 according to the first embodiment with respect to the spool valve 32, and the rest is the pulse tube according to the first embodiment. It has the same configuration as the refrigerator 10. Hereinafter, the pulse tube refrigerator 10 according to the third embodiment will be mainly described with a configuration different from that of the first embodiment, and the common configuration will be briefly described or omitted.

The spool valve 32 includes a back pressure chamber 74 adjacent to the spool 36 on the opposite side of the valve drive chamber 34, and a connection flow path 76 sealed from the valve drive chamber 34 and the back pressure chamber 74. The connection flow path 76 connects the cold storage high temperature end 18a to the compressor discharge port 12a when the spool 36 is in the first position, and connects the cold storage high temperature end 18a to the compressor suction port 12b when the spool 36 is in the second position. Connect to.

Further, the spool valve 32 has a plurality of sealing members arranged in a clearance between the spool 36 and the sleeve 56, specifically, a first sealing member 58a, a second sealing member 58b, a third sealing member 58c, and a third sealing member 58c. It has a fourth seal member 58d. By these sealing members, the working gas space inside the spool valve 32 is separated into a valve drive chamber 34, a first clearance region 60a, a second clearance region 60b, a third clearance region 60c, and a back pressure chamber 74. .. The back pressure chamber 74 is sealed from the third clearance region 60c by the fourth sealing member 58d.

An intermediate pressure buffer 78 is connected to the back pressure chamber 74. The back pressure chamber 74 communicates with the intermediate pressure buffer 78 through a through hole formed in the end surface of the sleeve 56 on the back pressure chamber 74 side. The intermediate pressure buffer 78 has an intermediate pressure PM between the high pressure PH and the low pressure PL (for example, the average pressure of the high pressure PH and the low pressure PL). Therefore, the pressure in the back pressure chamber 74 is maintained at the intermediate pressure PM.

The connection flow path 76 is arranged between the second seal member 58b and the third seal member 58c in the axial direction of the spool 36. Therefore, the connection flow path 76 communicates with the second clearance region 60b. In other words, the connecting flow path 76 extends the flow path width of the second clearance region 60b. The second clearance region 60b, that is, the connection flow path 76, communicates with the cooler flow path 50 through a through hole formed on the side surface of the sleeve 56. As an example, the connection flow path 76 is a groove formed on the cylindrical side surface of the spool 36, and extends in the circumferential direction of the spool 36 over the entire circumference. Alternatively, the connection flow path 76 may penetrate the spool 36 in the radial direction.

As shown in FIG. 7, in the intake process, the drive chamber exhaust valve V2 is opened and the drive chamber intake valve V1 is closed. The compressor suction port 12b is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a low pressure PL. Since the back pressure chamber 74 has an intermediate pressure PM, the spool 36 moves axially in the sleeve 56 so as to reduce the valve drive chamber 34 due to the pressure difference between the valve drive chamber 34 and the back pressure chamber 74.

When the spool 36 reaches the first position, that is, at or near the top dead center due to the upward movement of the spool 36, the second clearance region 60b is adjacent to the high pressure port 42. The high-pressure port 42 is connected to the cooler flow path 50 through the connection flow path 76, and the working gas of the high-pressure PH is supplied to the cooler 18 and the pulse tube 16 from the compressor discharge port 12a. At this time, the third clearance region 60c is adjacent to the low pressure port 44. Since the low pressure port 44 is blocked by the spool 36, the connection between the cool storage 18 and the pulse tube 16 and the compressor suction port 12b is cut off.

As shown in FIG. 8, in the exhaust process, the drive chamber intake valve V1 is opened and the drive chamber exhaust valve V2 is closed. The compressor discharge port 12a is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a high pressure PH. Since the back pressure chamber 74 has an intermediate pressure PM, the spool 36 moves axially in the sleeve 56 so as to expand the valve drive chamber 34 due to the pressure difference between the valve drive chamber 34 and the back pressure chamber 74.

When the spool 36 reaches the second position, that is, at or near the bottom dead center due to the downward movement of the spool 36, the second clearance region 60b is adjacent to the low pressure port 44. The low pressure port 44 is connected to the cooler flow path 50 through the connection flow path 76, the working gas is discharged to the compressor suction port 12b, and the pulse tube 16 and the cooler 18 become low pressure PL. At this time, the first clearance region 60a is adjacent to the high pressure port 42. Since the high pressure port 42 is blocked by the spool 36, the connection between the cool storage 18 and the pulse tube 16 and the compressor discharge port 12a is cut off.

In this way, the spool valve 32 functions as a main pressure switching valve of the pulse tube refrigerator 10 in which the compressor discharge port 12a and the compressor suction port 12b are alternately connected to the cold storage high temperature end 18a. The pressure control mechanism 38 alternately connects the compressor discharge port 12a and the compressor suction port 12b to the valve drive chamber 34 of the spool valve 32, and controls the pressure in the valve drive chamber 34 so as to appropriately drive the spool 36. be able to.

Also in the pulse tube refrigerator 10 according to the third embodiment, the pressure loss generated in the working gas in the spool valve 32 is reduced, and the drive source of the flow path switching mechanism for the pulse tube refrigerator 10 is large. It is possible to suppress the conversion at the same time. Therefore, it is advantageous as compared with the existing typical pulse tube refrigerator that employs a rotary valve as a flow path switching mechanism for the cold head.

Unlike the second gas chamber 35 described with reference to FIGS. 2 and 3, the back pressure chamber 74 according to the third embodiment is fluid from the working gas flow path from the spool valve 32 to the regenerator 18. Is isolated in. The back pressure chamber 74 does not form a dead volume. Therefore, the pulse tube refrigerator 10 according to the third embodiment has an advantage that the dead volume can be made smaller than that of the pulse tube refrigerator 10 according to the first embodiment.

9 and 10 are diagrams schematically showing another configuration of the pulse tube refrigerator 10 according to the third embodiment. It is not essential to provide the intermediate pressure buffer 78. As shown in FIG. 9, the back pressure chamber 74 may be connected to the buffer volume 26. Further, as shown in FIG. 10, instead of providing the intermediate pressure buffer 78, the back pressure chamber 74 may be connected to the cold storage high temperature end 18a. In this case, a third flow path resistance 80 such as an orifice connecting the back pressure chamber 74 to the cold storage high temperature end 18a may be provided for phase control or flow rate control. Even in this way, the dead volume can be reduced as described with reference to FIGS. 7 and 8.

11 and 12 are schematic views showing a working gas circuit configuration of the pulse tube refrigerator 10 according to the fourth embodiment. FIG. 11 shows an intake process of the pulse tube refrigerator 10, and FIG. 12 shows an exhaust process of the pulse tube refrigerator 10. The pulse tube refrigerator 10 according to the fourth embodiment is different from the pulse tube refrigerator 10 according to the third embodiment in terms of the spool valve 32, and the rest is the pulse tube according to the third embodiment. It has the same configuration as the refrigerator 10. Hereinafter, the pulse tube refrigerator 10 according to the fourth embodiment will be mainly described with a configuration different from that of the third embodiment, and the common configuration will be briefly described or omitted.

In the pulse tube refrigerator 10 according to the fourth embodiment, the spool 36 includes a set of opposed pistons 82. The two pistons 82 are housed in one sleeve 56, a valve drive chamber 34 is formed on one side of each piston 82, and a back pressure chamber 74 is formed on the opposite side, that is, between the two pistons 82.

The two pistons 82 have a similar configuration. Each piston 82 has four sealing members (58a-58d) arranged in a clearance between the piston 82 and the sleeve 56. By these sealing members, the working gas space inside the spool valve 32 is separated into a valve drive chamber 34, a first clearance region 60a, a second clearance region 60b, a third clearance region 60c, and a back pressure chamber 74. .. The back pressure chamber 74 is formed between the fourth seal member 58d of each of the two pistons 82.

The back pressure chamber 74 is connected to the cold storage high temperature end 18a through the third flow path resistance 80. However, this is not essential, and the back pressure chamber 74 may be connected to the intermediate pressure buffer 78, as shown in FIGS. 7 and 8. Alternatively, as shown in FIG. 9, the back pressure chamber 74 may be connected to the buffer volume 26.

Further, each piston 82 includes a connection flow path 76 sealed from the valve drive chamber 34 and the back pressure chamber 74. The connection flow path 76 connects the cold storage high temperature end 18a to the compressor discharge port 12a when the piston 82 is in the first position, and connects the cold storage high temperature end 18a to the compressor suction port 12b when the piston 82 is in the second position. Connect to. The connection flow path 76 communicates with the second clearance region 60b.

Since the spool valve 32 has two connection flow paths 76, the high pressure line 13a extends from the compressor discharge port 12a so as to be connected to these connection flow paths 76 and branches into two in the middle. Similarly, the low pressure line 13b extends from the compressor suction port 12b so as to be connected to the two connection flow paths 76 and branches into two in the middle. The sleeve 56 has two high pressure ports 42 and two low pressure ports 44. The valve drive chamber line 46 extends from the pressure control mechanism 38 so as to be connected to the two valve drive chambers 34 and branches into two in the middle. The regenerator flow path 50 extends from the regenerator high temperature end 18a so as to be connected to the two connection flow paths 76, and branches into two in the middle.

As shown in FIG. 11, in the intake process, the drive chamber exhaust valve V2 is opened and the drive chamber intake valve V1 is closed. The compressor suction port 12b is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a low pressure PL. Since the back pressure chamber 74 has an intermediate pressure PM, the two pistons 82 move axially in the sleeve 56 so as to reduce the valve drive chamber 34 due to the pressure difference between the valve drive chamber 34 and the back pressure chamber 74. The two pistons 82 move in opposite directions so as to separate from each other.

When each piston 82 reaches the first position in this way, the second clearance region 60b is adjacent to the high pressure port 42. The high-pressure port 42 is connected to the cooler flow path 50 through the connection flow path 76, and the working gas of the high-pressure PH is supplied to the cooler 18 and the pulse tube 16 from the compressor discharge port 12a. At this time, the third clearance region 60c is adjacent to the low pressure port 44. Since the low pressure port 44 is blocked by the piston 82, the connection between the cool storage 18 and the pulse tube 16 and the compressor suction port 12b is cut off.

As shown in FIG. 12, in the exhaust process, the drive chamber intake valve V1 is opened and the drive chamber exhaust valve V2 is closed. The compressor discharge port 12a is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a high pressure PH. Since the back pressure chamber 74 has an intermediate pressure PM, the two pistons 82 move axially in the sleeve 56 so as to expand the valve drive chamber 34 due to the pressure difference between the valve drive chamber 34 and the back pressure chamber 74. The two pistons 82 move in opposite directions so as to approach each other.

When each piston 82 reaches the second position in this way, the second clearance region 60b is adjacent to the low pressure port 44. The low pressure port 44 is connected to the cooler flow path 50 through the connection flow path 76, the working gas is discharged to the compressor suction port 12b, and the pulse tube 16 and the cooler 18 become low pressure PL. At this time, the first clearance region 60a is adjacent to the high pressure port 42. Since the high pressure port 42 is blocked by the piston 82, the connection between the cool storage 18 and the pulse tube 16 and the compressor discharge port 12a is cut off.

In this way, the spool valve 32 functions as a main pressure switching valve of the pulse tube refrigerator 10 in which the compressor discharge port 12a and the compressor suction port 12b are alternately connected to the cold storage high temperature end 18a. The pressure control mechanism 38 alternately connects the compressor discharge port 12a and the compressor suction port 12b to the valve drive chamber 34 of the spool valve 32, and controls the pressure in the valve drive chamber 34 so as to appropriately drive the piston 82. be able to.

Also in the pulse tube refrigerator 10 according to the fourth embodiment, the pressure loss generated in the working gas in the spool valve 32 is reduced, and the drive source of the flow path switching mechanism for the pulse tube refrigerator 10 is large. It is possible to suppress the conversion at the same time. Therefore, it is advantageous as compared with the existing typical pulse tube refrigerator that employs a rotary valve as a flow path switching mechanism for the cold head.

Further, according to the pulse tube refrigerator 10 according to the fourth embodiment, since the two pistons 82 are arranged to face each other and reciprocate in opposite directions to each other, the single spool 36 reciprocates as compared with the case where the single spool 36 reciprocates. The vibration generated by the spool valve 32 can be reduced.

FIG. 13 is a diagram schematically showing another configuration of the spool valve 32 applicable to the pulse tube refrigerator 10 according to the fourth embodiment. The spool valve 32 may include at least one damper 84 for damping vibration. The damper 84 may be arranged between the piston 82 and the sleeve 56 so as to cushion the impact of the collision between the piston 82 and the sleeve 56. Further, the damper 84 may be arranged between the two pistons 82 so as to reduce the impact of the collision between the two pistons 82. As shown in FIG. 13, dampers 84 may be installed in each of the two valve drive chambers 34 and the back pressure chamber 74. As an exemplary configuration, the damper 84 may include a fixing member 84a and a cushioning material 84b. By providing the damper 84, the vibration generated by the spool valve 32 can be further reduced.

The damper 84 may be arranged between the spool 36 and the sleeve 56 so as to reduce the impact of the collision between the spool 36 and the sleeve 56 in the spool valve 32 having one spool 36.

FIG. 14 is a diagram schematically showing another configuration of the pulse tube refrigerator 10 according to the fourth embodiment. The configuration of the opposed piston type spool valve 32 can also be applied to a 4-valve type pulse tube refrigerator. In this case, the spool valve 32 not only connects the compressor discharge port 12a and the compressor suction port 12b to the cold storage high temperature end 18a alternately, but also connects the compressor discharge port 12a and the compressor suction port 12b to the pulse tube high temperature end. It is also configured to be alternately connected to 16a. The pulse tube refrigerator 10 does not include a double inlet orifice 28 and a bypass flow path 54.

As shown in FIG. 14, the connection flow path 76 of one piston 82 (upper piston 82 in the figure) is connected to the cold storage high temperature end 18a through the cold storage flow path 50. Further, the connection flow path 76 of the other piston 82 (lower piston 82 in the figure) is connected to the pulse tube high temperature end 16a through the pulse tube flow path 86. The pulse pipe flow path 86 may be provided with a fourth flow path resistance 88 such as an orifice for phase control or flow rate control.

In this way, one piston 82 (upper piston 82 in the figure) operates so as to alternately connect the compressor discharge port 12a and the compressor suction port 12b to the cold storage high temperature end 18a, and the other piston. The 82 (lower piston 82 in the figure) can operate so as to alternately connect the compressor discharge port 12a and the compressor suction port 12b to the high temperature end 16a of the pulse tube.

15 and 16 are schematic views showing a working gas circuit configuration of the pulse tube refrigerator 10 according to the fifth embodiment. FIG. 15 shows the intake process of the pulse tube refrigerator 10, and FIG. 16 shows the exhaust process of the pulse tube refrigerator 10. The pulse tube refrigerator 10 according to the above-described embodiment is a double inlet type pulse tube refrigerator, whereas the pulse tube refrigerator 10 according to the fifth embodiment is a 4-valve type pulse tube refrigerator. It is configured. Hereinafter, the pulse tube refrigerator 10 according to the fifth embodiment will be mainly described with a configuration different from that of the first embodiment, and the common configuration will be briefly described or omitted.

The spool valve 32 not only connects the compressor discharge port 12a and the compressor suction port 12b to the cold storage high temperature end 18a alternately, but also connects the compressor discharge port 12a and the compressor suction port 12b to the pulse tube high temperature end 16a. It is configured to connect alternately. The spool valve 32 having a single spool 36 can also be configured as a 4-valve type pulse tube refrigerator. Since the pulse tube refrigerator 10 is a 4-valve type, unlike the first embodiment, the pulse tube refrigerator 10 does not include the double inlet orifice 28 and the bypass flow path 54.

The spool valve 32 includes a valve drive chamber 34 and a second gas chamber 35. The valve drive chamber 34 is formed between one end of the spool 36 and the sleeve 56, and the second gas chamber 35 is formed between the other end of the spool 36 and the sleeve 56. The spool 36 can move with respect to the sleeve 56 due to the pressure difference between the valve drive chamber 34 and the second gas chamber 35. A return spring 64 is provided between the spool 36 and the sleeve 56. The return spring 64 is housed in the second gas chamber 35.

The spool 36 includes a spool main flow path 62, a spool sub intake flow path 90, and a spool sub exhaust flow path 92. The spool main flow path 62 communicates the clearance between the spool 36 and the sleeve 56 to the second gas chamber 35. The spool main flow path 62 may be formed so as to penetrate the spool 36 from the side surface to the end surface of the spool 36. As an example, the spool sub-intake flow path 90 and the spool sub-exhaust flow path 92 are grooves formed on the cylindrical side surface of the spool 36, and extend all around the spool 36 in the circumferential direction. The spool sub-intake flow path 90 and the spool sub-exhaust flow path 92 are formed at different positions in the axial direction of the spool 36, one on the valve drive chamber 34 side and the other on the second gas chamber 35 side.

The sleeve 56 has two high pressure ports 42a, 42b and two low pressure ports 44a, 44b. One high pressure port 42a is provided in the sleeve 56 to communicate the compressor discharge port 12a with the spool main flow path 62, and the other high pressure port 42b communicates the compressor discharge port 12a with the spool sub intake flow path 90. Therefore, it is provided in the sleeve 56. The high-pressure line 13a extends from the compressor discharge port 12a so as to be connected to these high-pressure ports 42a and 42b, and branches into two in the middle. One low-pressure port 44a is provided in the sleeve 56 to communicate the compressor suction port 12b to the spool main flow path 62, and the other low-pressure port 44b communicates the compressor suction port 12b to the spool sub-exhaust flow path 92. Therefore, it is provided in the sleeve 56. The low-pressure line 13b extends from the compressor suction port 12b so as to be connected to these low-pressure ports 44a and 44b, and branches into two in the middle.

The valve drive chamber line 46 connects the pressure control mechanism 38 to the valve drive chamber 34. The cold storage flow path 50 connects the second gas chamber 35 to the cold storage high temperature end 18a. Further, the sleeve 56 has two pulse tube ports 94a and 94b. One pulse tube port 94a is provided in the sleeve 56 to communicate the pulse tube high temperature end 16a with the spool sub-intake flow path 90, and the other pulse tube port 94b connects the pulse tube high temperature end 16a to the spool sub-exhaust flow path. It is provided on the sleeve 56 to communicate with the 92. The pulse tube flow path 86 extends from the pulse tube high temperature end 16a so as to be connected to these pulse tube ports 94a and 94b, and branches into two in the middle. The pulse pipe flow path 86 may be provided with a fourth flow path resistance 88 such as an orifice for phase control or flow rate control.

The spool valve 32 has a plurality of sealing members (58a-58h) arranged in a clearance between the spool 36 and the sleeve 56. These eight sealing members (58a to 58h) are mounted on the spool 36 at different axial positions from each other and extend in the circumferential direction of the spool 36. The working gas space inside the spool valve 32 is separated into a valve drive chamber 34, a second gas chamber 35, and seven clearance regions (60a to 60g) by a sealing member (58a to 58h). The eight sealing members (58a to 58h) and the seven clearance regions (60a to 60g) are arranged alternately in the axial direction. The first seal member 58a is arranged between the valve drive chamber 34 and the first clearance region 60a, and the eighth seal member 58h is arranged between the seventh clearance region 60g and the second gas chamber 35. .. The spool sub-intake flow path 90 is arranged between the second seal member 58b and the third seal member 58c, and communicates with the second clearance region 60b. The spool sub-exhaust flow path 92 is arranged between the sixth seal member 58f and the seventh seal member 58g, and communicates with the sixth clearance region 60f.

As shown in FIG. 15, in the intake process, the drive chamber exhaust valve V2 is opened and the drive chamber intake valve V1 is closed. The compressor suction port 12b is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a low pressure PL. At this time, the second gas chamber 35 has a pressure slightly higher than that of the low pressure PL. At the start of the intake process, the spool 36 is located at or near bottom dead center. Due to the pressure difference between the valve drive chamber 34 and the second gas chamber 35, the spool 36 moves axially in the sleeve 56 so as to shrink the valve drive chamber 34. The restoring force of the return spring 64 also helps to move the spool 36 upward.

When the spool 36 reaches the first position, that is, at or near the top dead center due to the upward movement of the spool 36, the fourth clearance region 60d is adjacent to the high pressure port 42a. Further, the second clearance region 60b is adjacent to the high pressure port 42b and the pulse tube port 94a. Therefore, the high-pressure port 42a is connected to the second gas chamber 35 through the spool main flow path 62, the working gas of the high-pressure PH is supplied to the cooler 18 from the compressor discharge port 12a, and further to the pulse tube 16 through the cooling stage flow path 21. Will be supplied. Further, the high pressure port 42b is connected to the pulse pipe flow path 86 through the second clearance region 60b and the spool sub intake flow path 90, and the working gas of the high pressure PH is supplied to the pulse tube high temperature end 16a from the compressor discharge port 12a. ..

At this time, the low pressure port 44a is adjacent to the fifth clearance region 60e, and the low pressure port 44b is adjacent to the seventh clearance region 60g. Therefore, since the low pressure ports 44a and 44b are blocked by the spool 36, the connection between the cold storage 18 and the pulse tube 16 and the compressor suction port 12b is cut off. Further, since the sixth clearance region 60f is adjacent to the pulse tube port 94b, the connection from the pulse tube high temperature end 16a to the compressor suction port 12b through the spool sub-exhaust flow path 92 is also cut off.

As shown in FIG. 16, in the exhaust process, the drive chamber intake valve V1 is opened and the drive chamber exhaust valve V2 is closed. The compressor discharge port 12a is communicated with the valve drive chamber 34, and the pressure in the valve drive chamber 34 becomes a high pressure PH. At this time, the second gas chamber 35 has a pressure slightly lower than the high pressure PH. At the start of the exhaust process, the spool 36 is located at or near top dead center. Due to the pressure difference between the valve drive chamber 34 and the second gas chamber 35, the spool 36 moves axially in the sleeve 56 so as to expand the valve drive chamber 34. The restoring force of the return spring 64 also helps the spool 36 to move downward.

When the spool 36 reaches the second position, that is, at or near the bottom dead center due to the downward movement of the spool 36, the fourth clearance region 60d is adjacent to the low pressure port 44a. Further, the sixth clearance region 60f is adjacent to the low pressure port 44b and the pulse tube port 94b. Therefore, the low pressure port 44a is connected to the second gas chamber 35 through the spool main flow path 62, the working gas is discharged to the compressor suction port 12b, and the pulse tube 16 and the cooler 18 become low pressure PL. Further, the low pressure port 44b is connected to the pulse pipe flow path 86 through the sixth clearance region 60f and the spool sub-exhaust flow path 92, and the working gas is discharged from the pulse tube high temperature end 16a to the compressor suction port 12b.

At this time, the high pressure port 42a is adjacent to the third clearance region 60c, and the high pressure port 42b is adjacent to the first clearance region 60a. Since the high-pressure ports 42a and 42b are blocked by the spool 36, the connection between the cold storage 18 and the pulse tube 16 and the compressor suction port 12b is cut off. Further, since the second clearance region 60b is adjacent to the pulse tube port 94a, the connection from the compressor discharge port 12a to the pulse tube high temperature end 16a through the spool sub-intake flow path 90 is also cut off.

In this way, the spool valve 32 functions as a main pressure switching valve of the pulse tube refrigerator 10 in which the compressor discharge port 12a and the compressor suction port 12b are alternately connected to the cold storage high temperature end 18a. In addition, the spool valve 32 functions as an auxiliary pressure switching valve of the pulse tube refrigerator 10 that alternately connects the compressor discharge port 12a and the compressor suction port 12b to the pulse tube high temperature end 16a. The pressure control mechanism 38 alternately connects the compressor discharge port 12a and the compressor suction port 12b to the valve drive chamber 34 of the spool valve 32, and controls the pressure in the valve drive chamber 34 so as to appropriately drive the spool 36. be able to.

Also in the pulse tube refrigerator 10 according to the fifth embodiment, the pressure loss generated in the working gas in the spool valve 32 is reduced, and the drive source of the flow path switching mechanism for the pulse tube refrigerator 10 is large. It is possible to suppress the conversion at the same time. Therefore, it is advantageous as compared with the existing typical pulse tube refrigerator that employs a rotary valve as a flow path switching mechanism for the cold head.

17 to 19 are diagrams schematically showing other configurations of the pressure control mechanism 38 applicable to the pulse tube refrigerator 10 according to the embodiment. The pressure control mechanism 38 may have various specific configurations.

As shown in FIG. 17, the pulse tube refrigerator 10 may include a main compressor 12 and an auxiliary compressor 96. The compressor 12 is connected to the cold head 14 as a high pressure source and a low pressure source of the working gas for the cold head 14. The auxiliary compressor 96 is connected to the pressure control mechanism 38 as a high pressure source and a low pressure source of the working gas for the pressure control mechanism 38. In this way, the cold head 14 and the pressure control mechanism 38 may be operated using separate compressors.

As shown in FIG. 18, the pressure control mechanism 38 may include a linear compressor 97. The linear compressor 97 includes an actuator 97a such as an electromagnet, a compressor piston 97b that reciprocates by driving the actuator 97a, and a compression chamber 97c connected to a valve drive chamber line 46. In the compression chamber 97c, when the compressor piston 97b advances (when the compressor piston 97b moves to the left in FIG. 18), the working gas is compressed, and the high-pressure working gas flows from the compression chamber 97c through the valve drive chamber line 46. It is supplied to the valve drive chamber 34. When the compressor piston 97b retracts (when the compressor piston 97b moves to the right in FIG. 18), the pressure in the compression chamber 97c decreases, and thereby the pressure in the valve drive chamber 34 also decreases. In this way, the pressure control mechanism 38 can control the pressure in the valve drive chamber 34. As the linear compressor 97, a known configuration can be appropriately adopted.

As shown in FIG. 19, the pressure control mechanism 38 may include an actuator 98a, a bellows 98b or other movable membrane and a compression chamber 98c connected to the valve drive chamber line 46. The bellows 98b is deformed by the drive of the actuator 98a, whereby the working gas pressure of the compression chamber 98c is controlled. Therefore, the pressure control mechanism 38 can control the pressure in the valve drive chamber 34.

The present invention has been described above based on the examples. It will be understood by those skilled in the art that the present invention is not limited to the above embodiment, various design changes are possible, various modifications are possible, and such modifications are also within the scope of the present invention. By the way.

The various features described in relation to one embodiment are also applicable to other embodiments. The new embodiments resulting from the combination have the effects of each of the combined embodiments.

For example, the removable joint 68 described in the second embodiment is applied to the pulse tube refrigerator 10 according to the third embodiment, the fourth embodiment, or the fifth embodiment. You may. Alternatively, the removable joint 68 may be applied to the pulse tube refrigerator 10 described with reference to FIGS. 17 to 19.

10 Pulse tube refrigerator, 12 Compressor, 12a Compressor discharge port, 12b Compressor suction port, 14 Cold head, 16 Pulse tube, 18 Cold storage, 32 Spool valve, 34 Valve drive chamber, 36 Spool, 38 Pressure control mechanism , 66 Rotary valve, 68 Detachable joint, 74 Back pressure chamber, 76 Connection flow path, 82 Piston.

Claims (7)

A cold head provided with a pulse tube and a cold storage, in which the low temperature end of the pulse tube is connected to the low temperature end of the cold storage.
A valve drive chamber and a spool that moves between a first position and a second position according to the pressure of the valve drive chamber are provided, and the spool compresses the high temperature end of the regenerator at the first position. A spool valve that connects to the outlet and connects the high temperature end of the cooler to the compressor suction port at the second position.
A pressure control mechanism, which is located away from the cold head and controls the pressure in the valve drive chamber, is provided .
The spool is a pulse tube refrigerator comprising a set of opposed pistons . A cold head provided with a pulse tube and a cold storage, in which the low temperature end of the pulse tube is connected to the low temperature end of the cold storage.
A valve drive chamber and a spool that moves between a first position and a second position according to the pressure of the valve drive chamber are provided, and the spool compressor discharges the high temperature end of the regenerator at the first position. A spool valve that connects to the outlet and connects the high temperature end of the cooler to the compressor suction port at the second position.
A pressure control mechanism, which is located away from the cold head and controls the pressure in the valve drive chamber, is provided.
The spool valve is characterized by having a back pressure chamber adjacent to the spool on the opposite side of the valve drive chamber and held at an intermediate pressure between the pressure of the compressor discharge port and the pressure of the compressor suction port. Pulse tube refrigerator. The spool valve is a connection flow path sealed from the valve drive chamber and the back pressure chamber, and connects the high temperature end of the chiller to the compressor discharge port when the spool is in the first position. The pulse tube refrigerator according to claim 2 , further comprising a connection flow path for connecting the high temperature end of the cold storage device to the compressor suction port when the spool is in the second position. The pulse tube refrigerator according to any one of claims 1 to 3, further comprising a removable joint for connecting the valve drive chamber to the pressure control mechanism. The pulse tube refrigerator according to any one of claims 1 to 4 , wherein the spool valve is fixed to the cold head so as to be arranged adjacent to the high temperature end of the cold storage device. The pulse tube refrigeration according to any one of claims 1 to 5 , wherein the pressure control mechanism includes a rotary valve that alternately connects the compressor discharge port and the compressor suction port to the valve drive chamber. Machine. The pulse tube refrigerator according to any one of claims 1 to 6, wherein the spool valve alternately connects the compressor discharge port and the compressor suction port to the high temperature end of the pulse tube.

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