TWI839961B - How to disassemble a cryogenic freezer - Google Patents

Abstract

A method for disassembling a cryogenic freezer, the cryogenic freezer comprising: a housing (20) having a lower opening (21); a lower cover shell sealing the lower opening (21); a Scotch yoke (45) received in the housing (20), passing through the lower cover shell and extending out of the housing (20); and a Scotch yoke (54) detachably disposed in the housing (20) to guide the axial movement of the Scotch yoke (45). The method comprises the following steps: removing the lower cover shell from the housing (20); and taking the Scotch yoke (54) out of the housing (20) from the lower opening (21).

Description

How to disassemble a cryogenic freezer

The present invention relates to a method for decomposing a cryogenic freezer.

A cryogenic freezer is known, which comprises: a drive motor; a Scotch yoke that converts the rotation of the drive motor into a linear reciprocating motion; a housing on which the drive motor is mounted and in which the Scotch yoke is housed; and a guide that guides the linear reciprocating motion of the Scotch yoke and is disposed on the housing in a manner that limits the tilting motion around the rotating shaft. [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Application Publication No. 2015-55374

[The problem the invention is trying to solve]

During the years of using a cryogenic freezer in the field, the guide may wear out year by year due to sliding with the Scotch yoke. In particular, when the Scotch yoke is formed of a metal material and the guide is formed of a synthetic resin material, the guide is easily worn out. As the wear progresses, the guide becomes less able to perform its function.

One of the exemplary purposes of one aspect of the present invention is to provide a method for disassembling an ultra-low temperature freezer for replacing a Scottish guide. [Technical means for solving the problem]

According to one aspect of the present invention, a method for disassembling an ultra-low temperature freezer is provided. The ultra-low temperature freezer comprises: a housing having a lower opening; a lower cover shell sealing the lower opening; a Scotch yoke received in the housing, passing through the lower cover shell and extending out of the housing; and a Scotch yoke detachably disposed in the housing to guide the axial movement of the Scotch yoke. The method comprises the following steps: removing the lower cover shell from the housing; and taking the Scotch yoke out of the housing from the lower opening.

In addition, any combination of the above components or the components or expressions of the present invention may be replaced with each other between methods, devices, systems, etc., which is also effective as an aspect of the present invention. [Effects of the invention]

According to the present invention, a disassembly method of an ultra-low temperature freezer for replacing a Scottish yoke can be provided.

Hereinafter, the method for implementing 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 marked with the same symbols and repeated descriptions are omitted as appropriate. For the convenience of explanation, the scale or shape of each part of the diagram is appropriately set, and unless otherwise specifically mentioned, it is interpreted in a non-limiting manner. The implementation method is an example and does not limit the scope of the present invention in any way. All the features or their combinations described in the implementation method are not necessarily the essence of the invention.

FIG. 1 to FIG. 3 are diagrams schematically showing an ultra-low temperature freezer 10 of an embodiment. FIG. 1 shows the appearance of a cold head of the ultra-low temperature freezer 10, and FIG. 2 shows the internal structure of a low temperature portion of the cold head. FIG. 3 shows the internal structure of a drive portion of the cold head. The ultra-low temperature freezer 10 is usually arranged in a vacuum container (not shown) in such a manner that the low temperature portion is arranged in a vacuum container and the drive portion is arranged in an ambient environment (e.g., a room temperature atmospheric pressure environment) outside the vacuum container. As an example, the ultra-low temperature freezer 10 is a two-stage Gifford-McMahon (GM) freezer.

The cryogenic refrigerator 10 includes a compressor 12 and an expander 14. The compressor 12 is configured to recover the working gas of the cryogenic refrigerator 10 from the expander 14, increase the pressure of the recovered working gas, and supply the working gas to the expander 14 again. The compressor 12 and the expander 14 constitute a refrigeration cycle of the cryogenic refrigerator 10, so that the cryogenic refrigerator 10 can provide the desired cryogenic cooling. The expander 14 is sometimes also called a cold head. The working gas is also called a refrigerant gas, which is usually helium, but other suitable gases can also be used. For ease of understanding, arrows are used in Figure 1 to indicate the flow direction of the working gas.

In addition, usually, the pressure of the working gas supplied from the compressor 12 to the expander 14 and the pressure of the working gas recovered from the expander 14 to the compressor 12 are much higher than the atmospheric pressure, and can be respectively referred to as the first high pressure and the second high pressure. For the convenience of explanation, the first high pressure and the second high pressure are respectively referred to as high pressure and low pressure. Typically, the high pressure is, for example, 2 to 3 MPa. The low pressure is, for example, 0.5 to 1.5 MPa, for example, about 0.8 MPa. For the convenience of understanding, arrows are used to indicate the flow direction of the working gas.

The expander 14 includes a refrigerator cylinder 16, a displacer assembly (hereinafter, also referred to as a displacer) 18, and a refrigerator casing (hereinafter, also referred to as a casing) 20. The refrigerator cylinder 16 guides the linear reciprocating motion of the displacer 18, and forms an expansion chamber (32, 34) as an expansion space for the working gas between the refrigerator cylinder 16 and the displacer 18. The refrigerator cylinder 16 is fixed to the refrigerator casing 20, thereby constituting a frame of the expander 14, and an airtight space for accommodating the displacer 18 is formed in the refrigerator cylinder 16.

In this specification, in order to explain the positional relationship between the components of the ultra-low temperature freezer 10, for convenience, the upper static dead point side close to the axial reciprocating movement of the displacer is marked as "up", and the lower static dead point side is marked as "down". The upper static dead point is the position of the displacer where the volume of the expansion space becomes the largest, and the lower static dead point is the position of the displacer where the volume of the expansion space becomes the smallest. When the ultra-low temperature freezer 10 is in operation, a temperature gradient is generated in which the temperature decreases from the upper side of the axis to the lower side, so the upper side can also be called the high temperature side and the lower side can be called the low temperature side.

The freezer cylinder 16 includes a first cylinder 16a and a second cylinder 16b. For example, the first cylinder 16a and the second cylinder 16b are cylindrical components, and the diameter of the second cylinder 16b is smaller than the diameter of the first cylinder 16a. The first cylinder 16a and the second cylinder 16b are coaxially arranged, and the lower end of the first cylinder 16a is rigidly connected to the upper end of the second cylinder 16b.

The displacer assembly 18 includes a first displacer 18a and a second displacer 18b which are connected to each other and move as a whole. For example, the first displacer 18a and the second displacer 18b are cylindrical components, and the diameter of the second displacer 18b is smaller than the diameter of the first displacer 18a. The first displacer 18a and the second displacer 18b are coaxially arranged.

The first displacer 18a is housed in the first cylinder 16a, and the second displacer 18b is housed in the second cylinder 16b. The first displacer 18a can reciprocate in the axial direction along the first cylinder 16a, and the second displacer 18b can reciprocate in the axial direction along the second cylinder 16b.

As shown in FIG. 2 , the first displacer 18a accommodates the first cold storage device 26. The first cold storage device 26 is formed by filling the cylindrical body of the first displacer 18a with a metal wire mesh such as copper or other appropriate first cold storage material. The upper cover and the lower cover of the first displacer 18a can be provided as components different from the body of the first displacer 18a, and the upper cover and the lower cover of the first displacer 18a can also be fixed to the body by an appropriate method such as fastening or welding, so that the first cold storage material is accommodated in the first displacer 18a.

Similarly, the second displacer 18b accommodates the second cold storage device 28. The second cold storage device 28 is formed by filling the cylindrical body of the second displacer 18b with a non-magnetic cold storage material such as bismuth, a magnetic cold storage material such as HoCu2, or other appropriate second cold storage material. The second cold storage material may also be formed into particles. The upper cover and the lower cover of the second displacer 18b may be provided as components different from the body of the second displacer 18b, and the upper cover and the lower cover of the second displacer 18b may also be fixed to the body by appropriate methods such as fastening and welding, so that the second cold storage material is accommodated in the second displacer 18b.

The displacer 18 forms an upper chamber 30, a first expansion chamber 32, and a second expansion chamber 34 inside the refrigerator cylinder 16. In order to exchange heat with a desired object or medium to be cooled by the ultra-low temperature refrigerator 10, the expansion machine 14 has a first cooling stage 33 and a second cooling stage 35. The upper chamber 30 is formed between the upper cover of the first displacer 18a and the upper part of the first cylinder 16a. The first expansion chamber 32 is formed between the lower cover of the first displacer 18a and the first cooling stage 33. The second expansion chamber 34 is formed between the lower cover of the second displacer 18b and the second cooling stage 35. The first cooling stage 33 is fixed to the lower portion of the first cylinder 16a in a manner surrounding the first expansion chamber 32, and the second cooling stage 35 is fixed to the lower portion of the second cylinder 16b in a manner surrounding the second expansion chamber 34.

The first regenerator 26 is connected to the upper chamber 30 via a working gas flow path 36a formed in the upper cover of the first displacer 18a, and is connected to the first expansion chamber 32 via a working gas flow path 36b formed in the lower cover of the first displacer 18a. The second regenerator 28 is connected to the first regenerator 26 via a working gas flow path 36c formed from the lower cover of the first displacer 18a to the upper cover of the second displacer 18b. Furthermore, the second regenerator 28 is connected to the second expansion chamber 34 via a working gas flow path 36d formed in the lower cover of the second displacer 18b.

In order to prevent the working airflow between the first expansion chamber 32, the second expansion chamber 34 and the upper chamber 30 from being introduced into the gap between the refrigerator cylinder 16 and the displacer 18, and to be introduced into the first cold storage device 26 and the second cold storage device 28, a first seal 38a and a second seal 38b may be provided. The first seal 38a may be installed on the upper cover of the first displacer 18a in a manner of being arranged between the first displacer 18a and the first cylinder 16a. The second seal 38b may be installed on the upper cover of the second displacer 18b in a manner of being arranged between the second displacer 18b and the second cylinder 16b.

As shown in FIG3 , the freezer housing 20 comprises: a housing body 22 having a lower opening 21; and a lower cover 24 that seals the lower opening 21. The lower opening 21 is formed on the lower surface of the housing body 22. As shown in the figure, the housing internal volume 20a formed by the housing body 22 and the lower cover 24 can also be connected to the low-pressure side of the compressor 12 to maintain a low pressure.

The lower cover shell 24 separates the housing internal volume 20a from the displacer storage space (upper chamber 30) in the freezer cylinder 16. The lower cover shell 24 has a disc shape as a whole, and more specifically, has a large diameter portion on the upper side and a small diameter portion on the lower side. The first sealing member 25a is provided between the lower cover shell 24 and the freezer cylinder 16 to maintain the airtightness of the internal volume of the freezer cylinder 16, and the second sealing member 25b is provided between the lower cover shell 24 and the housing body 22 to maintain the airtightness of the housing internal volume 20a. As shown in the figure, the first sealing member 25 a may also be installed at the small diameter portion of the lower cover shell 24 , and the second sealing member 25 b may also be installed at the large diameter portion of the lower cover shell 24 .

The lower cover shell 24 is detachably inserted into the lower opening 21, and the upper flange of the refrigerator cylinder 16 is fastened to the housing body 22 by fastening members such as bolts. In this way, the lower cover shell 24 is clamped between the housing body 22 and the upper flange of the refrigerator cylinder 16. The lower cover shell 24 is not fastened to the housing body 22. However, a structure in which the housing body 22 and the lower cover shell 24 are fastened by fastening members such as bolts may also be adopted.

The expander 14 includes an expander motor 40, a rotary valve 42, and a motion conversion mechanism 43. The expander motor 40 is mounted on the refrigerator housing 20, more specifically, on the side of the housing body 22. In order to maintain the airtightness of the housing internal volume 20a, a sealing member not shown may also be provided on the mounting surface of the expander motor 40 and the housing body 22. The rotary valve 42 and the motion conversion mechanism 43 are housed in the refrigerator housing 20.

The expander motor 40 is provided at the expander 14 as a driving source for the displacer 18 and the rotary valve 42. The expander motor 40 may be an appropriate electric motor, and may be configured to rotate the motor rotating shaft 40a at a constant rotation speed, or to be configured to variably control the rotation speed of the motor rotating shaft 40a.

The rotary valve 42 is configured to alternately connect the high-pressure side and the low-pressure side of the compressor 12 to the refrigerator cylinder 16 (i.e., the upper chamber 30, the first expansion chamber 32, and the second expansion chamber 34) to periodically switch the intake and exhaust of the refrigerator cylinder 16.

The rotary valve 42 includes a valve rotor 42a and a valve stator 42b, and the valve rotor 42a contacts the valve stator 42b in a manner of sliding and rotating relative to the valve stator 42b. The valve rotor 42a is supported to be rotatable relative to the housing body 22, and the valve stator 42b is supported to be non-rotatable relative to the housing body 22. An elastic body such as a spring may be interposed between the valve stator 42b and the housing body 22, and the elastic body is used to press the valve stator 42b toward the valve rotor 42a in the direction of the rotation axis of the valve rotor 42a.

The housing 20 of the freezer has a housing internal flow path 20b that connects the rotary valve 42 to the upper chamber 30, and the valve rotor 42a and the valve stator 42b of the rotary valve 42 have a valve internal flow path that alternately connects the housing internal flow path 20b to the high-pressure side of the compressor 12 and the housing internal volume 20a. The valve internal flow path can take a variety of known forms, which will not be described in detail here.

The motion conversion mechanism 43 is configured to connect the expander motor 40 with the rotary valve 42 and the displacer 18 so as to transmit the rotation of the motor rotating shaft 40a to the rotary valve 42 and convert it into a linear reciprocating movement of the displacer 18. An example of the motion conversion mechanism 43 will be described later. One rotation of the motor rotating shaft 40a causes one reciprocating movement of the displacer 18 via the motion conversion mechanism 43, so that the volume of the expansion space of the working gas changes periodically. At the same time, one rotation of the motor rotating shaft 40a causes one rotation of the rotary valve 42 via the motion conversion mechanism 43, so that the pressure of the expansion space of the working gas changes periodically.

In this way, the synchronous volume change and pressure change are brought into the expansion space, forming a refrigeration cycle of the ultra-low temperature freezer 10, so that the ultra-low temperature freezer 10 can provide the desired ultra-low temperature cooling. The first cooling stage 33 can cool to a first cooling temperature, and the second cooling stage 35 can cool to a second cooling temperature lower than the first cooling temperature. The first cooling temperature can be, for example, in the range of about 10K to about 100K, or in the range of about 20K to about 40K. The second cooling temperature can be, for example, below about 20K, below about 10K, or in the range of about 1K to about 4K.

Fig. 4 is a diagram schematically showing an exploded perspective view of a cold head drive unit of the cryogenic freezer 10 of the embodiment. Fig. 5 is a diagram schematically showing an exploded perspective view of a main part of a motion conversion mechanism 43 of the cold head of the embodiment. With reference to Figs. 3 to 5, an exemplary embodiment of the motion conversion mechanism 43 will be described.

The motion conversion mechanism 43 is a Scotch yoke in this embodiment, and includes a crank 44 having a crank pin 44a, a Scotch yoke 45, and a crank pin bearing 46. The Scotch yoke 45 includes a Scotch yoke plate 45a, an upper rod 45b, and a lower rod 45c. The Scotch yoke 45 can also be formed of a metal material such as stainless steel.

The crank 44 is fixed to the motor rotating shaft 40a. The crank pin 44a extends parallel to the motor rotating shaft 40a at a position eccentric from the motor rotating shaft 40a. The crank pin 44a extends from the crank 44 toward the side opposite to the motor rotating shaft 40a with respect to the crank 44.

The Scottish yoke 45a is a rectangular plate-shaped member having a transverse window 47. The transverse window 47 extends in the axial direction and in a direction perpendicular to the motor rotation shaft 40a. The crank pin bearing 46 is rollably arranged on the transverse window 47. The crank pin bearing 46 may also be, for example, a roller bearing. An engaging hole 46a engaging with the crank pin 44a is formed at the center of the crank pin bearing 46, and the crank pin 44a passes through the engaging hole 46a.

On the side opposite to the Scottish yoke 45a and the crank 44, the valve rotor 42a of the rotary valve 42 is arranged so that its central axis coincides with the motor rotation axis 40a, and the front end of the crank pin 44a passing through the engaging hole 46a is fixed to the valve rotor 42a.

The upper rod 45b extends upward from the center of the upper frame of the Scottish yoke 45a, and the lower rod 45c extends downward from the center of the lower frame of the Scottish yoke 45a, and these rods are coaxially arranged. The Scottish yoke 45a and the upper rod 45b are accommodated in the freezer housing 20, and the lower rod 45c penetrates the lower cover 24 and extends outside the freezer housing 20. The front end of the lower rod 45c is connected to the displacer 18 in the freezer cylinder 16.

The first sliding bearing 48a is disposed between the upper rod 45b and the housing body 22, and the second sliding bearing 48b is disposed between the lower rod 45c and the lower cover 24. The housing body 22 has a recessed portion at its upper portion for accommodating the upper rod 45b, and the first sliding bearing 48a is disposed in the recessed portion to support the upper rod 45b so that it can slide in the axial direction. The lower cover 24 has a through hole at the center portion, and the second sliding bearing 48b is disposed in the through hole to support the lower rod 45c so that it can slide in the axial direction. The second sliding bearing 48b is provided with a sealing portion such as a sliding seal or a clearance seal to form an airtight structure, so that the housing internal volume 20a is isolated from the upper chamber 30. There is no direct gas flow between the housing internal volume 20a and the upper chamber 30.

A collar portion 50 is fixed to the front end of the lower rod 45c connected to the displacer 18 by a fixing pin 49. The collar portion 50 is a short cylindrical member into which the front end of the displacer assembly 18 is inserted. A through hole is formed in the front end of the lower rod 45c and the collar portion 50 in a direction perpendicular to the axial direction, and the collar portion 50 and the lower rod 45c are fixed by inserting the fixing pin 49 into the through hole.

The first displacer 18a has a cover 52a and a main body 52b. The cover 52a is the upper cover of the first displacer 18a and has a disc shape. The cover 52a is formed of a metal material such as an aluminum alloy treated with an alumina film or other materials. The main body 52b has a cylindrical shape and has a cold storage device inside. The main body 52b is formed of a synthetic resin material or other materials, for example, it can also be formed of a phenolic resin such as Bakelite. The above-mentioned working gas flow path 36a is formed axially through the cover 52a and the upper end of the main body 52b. The above-mentioned first seal 38a can also be clamped between the cover 52a and the main body 52b at their respective outermost peripheries. The cover portion 52a and the body portion 52b are fixed to each other using fastening members such as bolts, or by other methods such as welding.

A through hole is formed in the center of the cover 52a to receive the front end of the lower rod 45c and the collar 50. The collar 50 has a flange portion that expands radially outward at its lower end, and the flange portion is clamped by the cover 52a and the body 52b of the first displacer 18a, so that the lower rod 45c and the collar 50 are connected to the first displacer 18a. In this way, the displacer 18 is mounted on the Scottish shaft 45.

Therefore, when the expander motor 40 is driven and the motor rotating shaft 40a rotates, the crank pin bearing 46 engaged with the crank pin 44a rotates in a circular manner. At this time, the crank pin bearing 46 reciprocates in the transverse window 47 of the Scottish yoke 45a, and at the same time, the Scottish yoke 45 and the displacer 18 reciprocate in the axial direction. In this way, the expander motor 40 drives the axial movement of the Scottish yoke 45.

Fig. 6 (a) and Fig. 6 (b) are diagrams schematically showing the Scottish guide 54 of the embodiment. Fig. 6 (a) schematically shows a cross section of the housing body 22 along the A-A cross section shown in Fig. 3, and Fig. 3 (b) schematically shows a part of the B-B cross section shown in Fig. 6 (a).

As shown in the figure, in this embodiment, a Scotch guide 54 is provided. The Scotch guide 54 is configured to guide the axial movement of the Scotch shaft 45 and restrict the axial rotation of the Scotch shaft 45.

The Scotch guide 54 has a plurality of (two in this example) pins 54a and 54b, each of which extends in the axial direction of the Scotch shaft 45. The pins 54a and 54b have a cylindrical shape and can be formed of a synthetic resin material with excellent wear resistance such as fluorine resin or other materials. The housing body 22 has a plurality of (two in this example) pin insertion holes 56, and the plurality of pins 54a and 54b are respectively detachably inserted into the pin insertion holes 56. Therefore, the Scotch guide 54 is detachably arranged in the freezer housing 20. As described later, the Scottish shaft 45 and the Scottish guide 54 can be taken out of the housing body 22 through the lower opening 21 of the housing body 22 .

The scotch guide 54 is arranged at a position different from the lower rod 45c in the direction of the motor rotation shaft 40a that drives the axial movement of the scotch shaft 45, and is adjacent to the scotch yoke 45a. In this embodiment, the scotch guide 54 is offset toward the motor rotation shaft 40a side relative to the scotch yoke 45a and the lower rod 45c, but it can also be arranged on the rotary valve 42 side.

The cylindrical side surface of each pin 54a of the Scotch yoke 54 contacts the side surface 58 of the Scotch yoke 45a formed with the transverse window 47. One pin 54a contacts the side surface 58 at the right frame portion of the Scotch yoke 45a, and the other pin 54a contacts the side surface 58 at the left frame portion of the Scotch yoke 45a.

Therefore, the Scotch guide 54 can guide the axial movement of the Scotch yoke 45a on the side of each pin 54a. In addition, the Scotch guide 54 can restrict the axial rotation of the Scotch yoke 45 by the pin 54a.

FIG. 7 and FIG. 8 are diagrams schematically showing a method of disassembling the ultra-low temperature freezer 10 according to an embodiment. First, as shown in FIG. 7 , the expander motor 40 is disassembled from the freezer housing 20 (S10). The fastening member that fixes the expander motor 40 to the freezer housing 20 is disassembled, and the expander motor 40 is disassembled from the side of the housing body 22. The expander motor 40 and the crank 44 may also be disassembled together. At the same time, the high-pressure piping and the low-pressure piping installed in the freezer housing 20 are also disassembled.

Next, the fixing of the freezer housing 20 and the freezer cylinder 16 is released (S11). As described above, the housing body 22 is mounted on the freezer cylinder 16 by the fastening member, and the freezer housing 20 is removed from the freezer cylinder 16 by removing the fastening member. Then, the freezer housing 20 is lifted from the freezer cylinder 16. Thereby, the displacer 18 can be pulled out of the freezer cylinder 16 together with the freezer housing 20.

Next, the displacer 18 is removed from the Scottish yoke 45 (S12). The fixing of the cover 52a and the main body 52b of the first displacer 18a is released, and the main body 52b is removed from the cover 52a. Furthermore, the fixing pin 49 and the collar 50 are removed from the lower rod 45c of the Scottish yoke 45, and the cover 52a is also removed (S13). In this way, before removing the lower cover shell 24 from the freezer housing 20, the displacer 18 is removed from the Scottish yoke 45. Then, the lower cover shell 24 is removed from the freezer housing 20 (S13).

As shown in FIG8 , the second sealing member 25b is removed from the housing body 22 (S14). In addition, FIG8 shows the housing body 22 upside down (i.e., with the lower opening 21 facing upward) for easy understanding. As described above, the second sealing member 25b is sandwiched between the lower cover 24 and the housing body 22 and is disposed in the lower opening 21. By removing the lower cover 24 from the housing body 22, the second sealing member 25b is taken out from the lower opening 21 that is opened again.

Next, the Scottish shaft 45 is pulled out of the freezer housing 20 from the lower opening 21 (S15). By removing the Scottish shaft 45 before removing the Scottish guide 54, the working space for removing the Scottish guide 54 can be expanded in the freezer housing 20.

Then, the Scottish guide 54 is taken out of the freezer housing 20 from the lower opening 21. First, one pin 54a is taken out of the freezer housing 20 through the lower opening 21 (S16), and then another pin 54b is also taken out of the freezer housing 20 through the lower opening 21 (S17).

After the pins 54a and 54b are removed in this way, new pins 54a and 54b are installed. Then, the expander 14 is assembled again in the reverse order of the above. In this way, the worn Scottish guide 54 can be replaced with a new one. Thereby, the Scottish guide 45 can be reliably prevented from rotating around the axis.

The present invention is described using specific words based on the implementation method, but the implementation method only represents one aspect of the principle and application of the present invention. Many variations or configuration changes can be made to the implementation method without departing from the scope of the idea of the present invention defined by the technical solution. [Industrial Applicability]

The present invention can be used in the field of decomposition methods of ultra-low temperature freezers.

10: Cryogenic freezer 21: Lower opening 24: Lower cover 40a: Motor rotation shaft 45: Scottish yoke 45a: Scottish yoke plate 54: Scottish yoke guide 54a: Pin 56: Pin insertion hole

[Figure 1] is a diagram schematically showing an ultra-low temperature freezer of an embodiment. [Figure 2] is a diagram schematically showing an ultra-low temperature freezer of an embodiment. [Figure 3] is a diagram schematically showing an ultra-low temperature freezer of an embodiment. [Figure 4] is a diagram schematically showing an exploded perspective view of a cold head drive unit of an ultra-low temperature freezer of an embodiment. [Figure 5] is a diagram schematically showing an exploded perspective view of a main part of a motion conversion mechanism of a cold head of an embodiment. [Figure 6], Figures 6(a) and 6(b) are diagrams schematically showing a Scottish guide of an embodiment. [Figure 7] is a diagram schematically showing a method for disassembling an ultra-low temperature freezer of an embodiment. [Figure 8] is a diagram schematically showing the disassembly method of the ultra-low temperature freezer in the implementation method.

20: Freezer casing

21: Lower opening

22: Shell body

25b: Second sealing member

45: Scottish axis

54: Scottish yoke guide

54a,54b: Pin

Claims (8)

A method for disassembling an ultra-low temperature freezer, wherein the ultra-low temperature freezer comprises: a housing having a lower opening; a lower cover shell sealing the lower opening; a Scotch yoke housed in the housing, penetrating the lower cover shell and extending out of the housing; and a Scotch yoke detachably disposed in the housing to guide the axial movement of the Scotch yoke. The method is characterized by comprising the following steps: Removing the lower cover shell from the housing; and Taking the Scotch yoke out of the housing from the lower opening. A method as described in claim 1, wherein the Scottish yoke is configured to limit the axial rotation of the Scottish yoke. A method as described in claim 1 or claim 2, wherein, the aforementioned Scotch yoke comprises: a Scotch yoke accommodated in the aforementioned housing; and a rod extending from the aforementioned Scotch yoke through the aforementioned lower cover shell to the outside of the aforementioned housing, the aforementioned Scotch yoke guide is arranged at a position different from the aforementioned rod in the direction of the motor rotation axis driving the axial movement of the aforementioned Scotch yoke, and is adjacent to the aforementioned Scotch yoke. The method as described in claim 1 or claim 2, wherein, the aforementioned Scottish yoke has a plurality of pins extending along the axial direction of the aforementioned Scottish yoke, and the aforementioned housing has a plurality of pin insertion holes for the aforementioned plurality of pins to be detachably inserted. The method as described in claim 1 or claim 2, wherein, further comprises the following steps: before removing the aforementioned Scottish guide, pulling the aforementioned Scottish shaft out of the aforementioned housing from the aforementioned lower opening. The method as described in claim 1 or claim 2, wherein, the ultra-low temperature freezer is provided with a displacer mounted on the Scottish shaft, the method further comprises the following step: before removing the lower cover shell from the shell, removing the displacer from the Scottish shaft. The method as described in claim 6, wherein, the ultra-low temperature freezer is provided with a cylinder, which is fixed to the housing and accommodates the displacer, the method comprises the following steps: releasing the fixing of the housing and the cylinder; and pulling the displacer out of the cylinder together with the housing. The method as described in claim 1 or claim 2, wherein, the ultra-low temperature freezer is provided with a motor, which is mounted on the housing and drives the axial movement of the Scottish shaft, the method further comprises the following steps: removing the motor from the housing.

Images