CO-AXIAL DOUBLE-INLET VALVE FOR PULSE TUBE CRYOCOOLER

Abstract

A Gifford-McMahon (GM) type double-inlet pulse tube system providing cooling at cryogenic temperatures is provided. The system has a co-axial double-inlet valve that includes a base having an adjustable port, a fixed needle partially engaged in one end of the adjustable port, an adjustable needle partially engaged in another end of said adjustable port, and a body for housing the base, the fixed needle and the adjustable needle. The base is configured to be adjustable along an axial direction. The adjustable needle is arranged co-axially with the fixed needle. The adjustable port and the adjustable needle are configured to control an alternating current (AC) flow and a direct current (DC) flow between the stem port and the end port and to produce the DC flow in either direction between the stem port and the end port.

Claims

1. A Gifford-McMahon (GM) type double-inlet pulse tube system providing cooling at cryogenic temperatures, comprising: a co-axial double-inlet valve comprising: a base having an adjustable port, wherein the base is configured to be adjustable along an axial direction; a fixed needle partially engaged in one end of the adjustable port; an adjustable needle partially engaged in another end of said adjustable port, wherein the adjustable needle is arranged co-axially with the fixed needle; and a body for housing the base, the fixed needle and the adjustable needle.

2. The GM type double-inlet pulse tube system of claim 1 wherein the base and the adjustable needle are adjustable from the same side of the body.

3. The GM type double-inlet pulse tube system of claim 1 wherein the base defines a cavity connected to a stem port formed on the body, the body defines a cavity connected to an end port formed on the body, and the adjustable port is located between the cavity of the base and the cavity of the body.

4. The GM type double-inlet pulse tube system of claim 3 wherein the adjustable port and the adjustable needle are configured to control an alternating current (AC) flow and a direct current (DC) flow between the stem port and the end port.

5. The GM type double-inlet pulse tube system of claim 3 wherein the adjustable port and the adjustable needle are configured to produce a DC flow in either direction between the stem port and the end port.

6. The GM type double-inlet pulse tube system of claim 3 wherein the co-axial double-inlet valve further comprises an adjustable needle base located in the cavity of the base, and the adjustable needle is integral to the adjustable needle base.

7. A Gifford-McMahon (GM) type double-inlet pulse tube system providing cooling at cryogenic temperatures, comprising; a compressor supplying gas at a supply pressure through a supply line and receiving gas at a return pressure through a return line; a valve assembly connected to the supply and return lines; a pulse tube cold head connected to the valve assembly, wherein the valve assembly cycles gas between the supply pressure and the return pressure to the pulse tube cold head through a connecting line, the pulse tube cold head comprising: a regenerator having a warm end and a cold end; a pulse tube having a warm end and a cold end; a co-axial double-inlet valve comprising: a base having an adjustable port, wherein the base is configured to be adjustable along an axial direction; a fixed needle partially engaged in one end of the adjustable port; an adjustable needle partially engaged in another end of said adjustable port, wherein the adjustable needle is arranged co-axially with the fixed needle; and a body for housing the base, the fixed needle and the adjustable needle; a first line extending from the connecting line to the warm end of the regenerator, wherein the co-axial double-inlet valve is connected to the first line; a second line connecting the cold end of the regenerator to the cold end of the pulse tube; a third line extending from the warm end of the pulse tube to a buffer volume through a single-inlet valve; and a fourth line extending from the co-axial double-inlet valve to the warm end of the pulse tube.

8. The GM type double-inlet pulse tube system of claim 7 wherein the base and the adjustable needle are adjustable from the same side of the body.

9. The GM type double-inlet pulse tube system of claim 7 wherein the base defines a cavity connected to a stem port formed on the body, the body defines a cavity connected to an end port formed on the body, and the adjustable port is located between the cavity of the base and the cavity of the body.

10. The GM type double-inlet pulse tube system of claim 9 wherein the stem port is connected to the first line and the end port is connected to the fourth line.

11. The GM type double-inlet pulse tube system of claim 9 wherein the adjustable port and the adjustable needle are configured to control an alternating current (AC) flow and a direct current (DC) flow between the stem port and the end port.

12. The GM type double-inlet pulse tube system of claim 9 wherein the adjustable port and the adjustable needle are configured to produce a DC flow in either direction between the stem port and the end port.

13. The GM type double-inlet pulse tube system of claim 9 wherein the co-axial double-inlet valve further comprises an adjustable needle base located in the cavity of the base, and the adjustable needle is integral to the adjustable needle base.

14. The GM type double-inlet pulse tube system of claim 7 wherein the connecting line between the valve assembly and the pulse tube cold head is a single flexible hose.

15. The GM type double-inlet pulse tube system of claim 7 wherein the connecting line between the valve assembly and the pulse tube cold head is at least 0.5 meter long.

16. The GM type double-inlet pulse tube system of claim 7 wherein the pulse tube cold head further comprises: a second stage regenerator connected to the cold end of the regenerator; a second stage pulse tube having a warm end and a cold end; a second stage co-axial double-inlet valve connected to the first line, comprising; a base having an adjustable port, wherein the base is configured to be adjustable along an axial direction; a fixed needle partially engaged in one end of the adjustable port; an adjustable needle partially engaged in another end of said adjustable port, wherein the adjustable needle is arranged co-axially with the fixed needle; and a body for housing the base, the fixed needle and the adjustable needle; a fifth line connecting an cold end of the second stage regenerator to the cold end of the second stage pulse tube; a sixth line extending from the warm end of the second stage pulse tube to a second stage buffer volume through a second stage single-inlet valve; and a seventh line extending from the second stage co-axial double-inlet valve to the warm end of the second stage pulse tube.

17. The GM type double-inlet pulse tube system of claim 16 wherein at least one of the adjustable port, fixed needle and adjustable needle of the second stage co-axial double-inlet valve has a different size from corresponding one of the adjustable port, fixed needle and adjustable needle of the co-axial double-inlet valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawing figures depict one or more implementations in accord with the present concepts, by way of example only, not by way of limitations. In the figures, like reference numerals refer to the same or similar elements.

[0015] FIG. 1 shows a schematic of a single stage GM type double-inlet pulse tube system having a co-axial double-inlet valve of this invention.

[0016] FIG. 2 shows a schematic of a co-axial double-inlet valve of this invention.

[0017] FIG. 3 shows a schematic of a two stage GM type double-inlet pulse tube system having two co-axial double-inlet valves of this invention.

DETAILED DESCRIPTIONS

[0018] In this section, some embodiments of the invention will be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments. Parts that are the same or similar in the drawings have the same numbers and descriptions are usually not repeated.

[0019] With reference to FIG. 1, shown is a schematic of a single stage GM type double-inlet pulse tube system 100 having a co-axial double-inlet valve 1 of the disclosed invention. The co-axial double-inlet valve 1 is shown in context of the entire system. The single stage GM type double-inlet pulse tube system 100 includes a compressor 10, a valve assembly 12 including valves 12a and 12b, and a pulse tube cold head 101 that is connected to the valve assembly 12 through connecting line 7a. Compressor 10 is connected to supply valve 12a, V1, through supply line 11a, and return valve 12b, V2, through return line 11b. Lines 11a and 11b are typically flexible metal hoses 5 to 20 meter long, and valves 12a and 12b are typically slots in a motor driven rotary valve rotating over ports in a stationary seat. Gas, usually helium, cycles in pressure between the supply and return pressures, typically 2.2 MPa and 0.6 MPa, as it flows through connecting line 7a to the warm end of the double-inlet pulse tube 17. The compressor 10 supplies gas at a supply pressure through a supply line 11a and receives gas at a return pressure through a return line 11b. The valves 12a and 12b are respectively connected to the supply line 11a and return line 11b that cycles gas between the supply pressure and the return pressure, through a connecting line 7a, to a pulse tube cold head 101. Connecting line 7a can be a few millimeters long if valves 12a and 12b are integral to the cold head 101 or it can be a single flexible hose up to 0.5 meter long or more if the valves are remote.

[0020] The pulse tube cold head 101 includes regenerator 16 having a warm end 16a and a cold end 16b, pulse tube 17 having a warm flow smoother 17a at a warm end and a cold flow smoother 17b at a cold end, line 18 connecting the regenerator cold end 16b of the regenerator 16 to the cold flow smoother 17b of the pulse tube 17, line 7b extending from the connecting line 7a to the warm end 16a of the regenerator 16, line 9a extending from the line 7b to a co-axial double-inlet valve 1, line 8 extending from the warm flow smoother 17a of the pulse tube 17 to a buffer volume 15 through a single-inlet valve 2, and line 9b extending from the co-axial double-inlet valve 1 to the line 8 and to the warm flow smoother 17a of the pulse tube 17. Cycling flow continues to the warm end 16a of regenerator 16 through line 7b, and to the co-axial double-inlet valve 1, line 9b and line 8 through line 9a. Line 8 connects at one end to the warm end of pulse tube 17, which contains warm flow smoother 17a, and at the other end to single-inlet valve 2, which in turn connects to buffer volume 15. The cold end 16b of regenerator 16 connects through line 18 to the cold end of pulse tube 17 which contains cold flow smoother 17b.

[0021] With reference to FIG. 2, shown is a schematic of co-axial double-inlet valve 1. Valve body 6 of the co-axial double-inlet valve 1 is typically the warm flange of the pulse tube cold end 101 but may be part of an external piping assembly. Needle 5a is integral to needle base 5 which is fixed in valve body 6. Valve port base 4, which has holes for gas to flow through, is co-axially aligned with needles 3a and 5a, and the valve port base 4 is axially adjustable by a threaded engagement in valve body 6. Needle 3a is integral to adjustable needle base 3 which is axially adjustable by a threaded engagement in port base 4. The port base 4 has an adjustable port 4a in which the needles 3a and 5a may be partially inserted. Slots 3b and 4b allow engagement of a tool to rotate needle base 3 and port base 4 independently from the same end of valve body 6 to adjust the needle base 3 and port base 4. Seals 3c and 4c are used to make the co-axial double-inlet valve 1 airtight.

[0022] Referring to FIG. 2, the body 6 has a hole 6a inside the body 6, and the fixed needle base 5 and the valve port base 4 are disposed in the hole 6a. The valve port base 4 has the adjustable port 4a and a hole (or cavity) 4d inside the valve port base 4, and the adjustable needle base 3 is disposed in the hole 4d. The hole 4d is connected to a stem port 4e which is connected to the line 9a which is connected to the line 7b as shown in FIG. 1. The adjustable needle 3a extending from the adjustable needle base 3 is disposed in the hole 4d and is partially disposed inside the adjustable port 4a. The fixed needle 5a extending from the fixed needle base 5 is disposed in the hole 5b and is partially disposed inside the adjustable port 4a. When the valve port base 4 and/or the adjustable needle base 3 are adjusted along the axial direction Z, the size of the hole 4d and the length of a portion of the needle 3a that is disposed inside the adjustable port 4a may be adjusted. When the valve port base 4 is adjusted along the axial direction Z, the adjustable port 4a moves along the axial direction Z and the length of a portion of the needle 5a which is disposed inside the adjustable port 4a may be adjusted.

[0023] The hole (or cavity) 5b may be formed between the valve port base 4 and the fixed needle base 5, and is connected to the hole 4d through the adjustable port 4a. The fixed needle body 5 is disposed between the hole 5b and the end port 5c, and has at least one connection port 5d. The end port 5c is connected to the port 5b through the connection port 5d. The end port 5c is connected to the line 9b which is connected to the line 8 as shown in FIG. 1. While the drawing shows a specific shape, but not the sizes, of needles 3a and 5a, and port 4a, other configurations are within the scope of this invention. If needles 3a and 5a are withdrawn from port 4a symmetrically, then the AC flow rate increases symmetrically, and if one is open more than the other, then the flow is asymmetric, the resistance for flow from the needle to the base that is more engaged being greater than that for flow from the needle that is less engaged. This asymmetry introduces DC flow, which can be set in either direction by which of the two needles is more engaged.

[0024] With reference to FIG. 3, shown is a schematic of a two stage GM type double-inlet pulse tube system 200 having multiple co-axial double-inlet valves 1a and 1b of the disclosed invention. The two stage GM type double-inlet pulse tube system 200 includes a compressor 10, a valve assembly 12 including valves 12a and 12b, and a pulse tube cold head 201 that is connected to the valve assembly 12 through connecting line 7a. Compressor 10 is connected to supply valve 12a, V1, through supply line 11a, and return valve 12b, V2, through return line 11b. Lines 11a and 11b are typically flexible metal hoses 5 to 20 meter long, and valves 12a and 12b are typically slots in a motor driven rotary valve rotating over ports in a stationary seat. Gas, usually helium, cycles in pressure between the supply and return pressures, typically 2.2 MPa and 0.6 MPa, as it flows through connecting line 7a to the warm end of the double-inlet pulse tubes 17 and 21. The compressor 10 supplies gas at a supply pressure through a supply line 11a and receives gas at a return pressure through a return line 11b. The valves 12a and 12b are respectively connected to the supply line 11a and return line 11b that cycles gas between the supply pressure and the return pressure, through a connecting line 7a, to a pulse tube cold head 201. Connecting line 7a can be a few millimeters long if valves 12a and 12b are integral to the cold head 201 or it can be a single flexible hose up to 0.5 meter long or more if the valves are remote.

[0025] Referring to FIG. 3, the pulse tube cold head 201 includes first stage regenerator 16′ having a warm end 16a′ and a cold end 16b′, second stage regenerator 20 attached to the cold end 16b′ of the first stage regenerator 16′ and having a cold end 20b, first stage pulse tube 17 having a warm flow smoother 17a at a warm end and a cold flow smoother 17b at a cold end, second stage pulse tube 21 having a warm flow smoother 21a at a warm end and a cold flow smoother 21b at a cold end, line 18 connecting the regenerator cold end 16b′ to the cold flow smoother 17b of the pulse tube 17, line 22 connecting the cold end 20b of the second stage regenerator 20 to the cold flow smoother 21b of the pulse tube 21, line 7b extending from the connecting line 7a to the warm end 16a′ of the regenerator 16′, line 9a extending from the line 7b to co-axial double-inlet valves 1a, line 9a′ extending from the line 7b to co-axial double-inlet valves 1b, line 8 extending from the warm flow smoother 17a of the pulse tube 17 to a buffer volume 15 through a single-inlet valve 2, line 8a extending from the warm flow smoother 21a of the pulse tube 21 to a buffer volume 15a through a single-inlet valve 2a, line 9b extending from the co-axial double-inlet valve 1a to the line 8 and to the warm flow smoother 17a of the pulse tube 17, and line 9b′ extending from the co-axial double-inlet valve 1b to the line 8a and to the warm flow smoother 21a of the pulse tube 21.

[0026] A first co-axial double-inlet valve 1a is connected to first stage pulse tube 17, and a second co-axial double-inlet valve 1b is connected to second stage pulse tube 21. The second co-axial double-inlet valve 1b includes the same elements as the first co-axial double-inlet valve 1a. The end port 5c of the second co-axial double-inlet valve 1b may be connected to the line 9b′ and the stem port 4e of the second co-axial double-inlet valve 1b may be connected to the line 9a′. The second co-axial double-inlet valve 1b is equivalent to the first co-axial double-inlet valve 1a but may have different sizes of the adjustable port 4a, needle 3a and needle 5a. As shown in FIG. 3 the second stage regenerator 20 is an extension of first stage regenerator 16′, and second stage pulse tube 21 is separate from first stage pulse tube 17, with the warm end at room temperature. The cold end 20b of regenerator 20 connects through line 22 to the cold end of pulse tube 21, which has flow smoother 21b. The warm end of second stage pulse tube 21 has flow smoother 21a and connects to line 8a, which connects to co-axial double-inlet valve 1b and buffer volume 15a through single-inlet valve 2a.

[0027] The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention and the embodiments described herein.