Oil separators and compressors for cryogenic refrigeration units

Abstract

The oil separator (20) comprises: an oil separator container (44); a refrigerant gas inlet pipe (52) inserted from the top of the oil separator container (44) and introducing refrigerant gas into the oil separator container (44); and a filter element (46) disposed within the oil separator container (44) and having an outer cavity (48) defined between the filter element (46) and the oil separator container (44). The filter element (46) has an inner cavity (50) connected to the refrigerant gas inlet pipe (52) and through which refrigerant gas is introduced, and the filter element (46) separates oil from the refrigerant gas flowing from the inner cavity (50) to the outer cavity (48). The filter element (46) has a lower dish-shaped body (60) installed at its lower end, and the oil separator container (44) is joined to the lower dish-shaped body (60) at its bottom.

Description

Technical Field

[0001] This invention relates to an oil separator and a compressor for ultra-low temperature refrigeration. Background Technology

[0002] To remove oil from the compressed and pressurized refrigerant gas, in many cases, the compressors used in cryogenic refrigerators incorporate oil separators and adsorbers. A small amount of oil mixes with the refrigerant gas flowing into the oil separator. The oil separator removes most of the oil from the refrigerant gas, but trace amounts may still flow out with it. The adsorber adsorbs these trace amounts of oil, thus removing the oil from the refrigerant gas.

[0003] Previous technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-202635 Summary of the Invention

[0006] The technical problem to be solved by the invention

[0007] The inventors studied the compressor described above and realized that there is room for improvement regarding the filter element in the oil separator from the viewpoint of reducing manufacturing costs.

[0008] One of the exemplary objects of one embodiment of the present invention is to reduce the manufacturing cost of filter elements in an oil separator.

[0009] means for solving technical problems

[0010] According to one embodiment of the present invention, an oil separator includes: an oil separator container; a refrigerant gas inlet pipe inserted from the upper part of the oil separator container and introducing refrigerant gas into the oil separator container; and a filter element disposed within the oil separator container, having an outer cavity defined between the filter element and the oil separator container. The filter element has an inner cavity connected to and through the refrigerant gas inlet pipe, and the filter element separates oil from the refrigerant gas flowing from the inner cavity to the outer cavity. The filter element includes a lower dish-shaped body installed at its lower end, and the oil separator container is joined to the lower dish-shaped body at its bottom.

[0011] According to one embodiment of the present invention, an oil separator includes: an oil separator container; a refrigerant gas inlet pipe inserted from the upper part of the oil separator container and introducing refrigerant gas into the oil separator container; and a filter element disposed within the oil separator container, having an outer cavity defined between the filter element and the oil separator container. The filter element has an inner cavity connected to and through the refrigerant gas inlet pipe, and the filter element separates oil from the refrigerant gas flowing from the inner cavity to the outer cavity. The filter element includes an upper dish-shaped body mounted on its upper end and having a recessed portion facing the inner cavity. The refrigerant gas inlet pipe is inserted into the inner cavity through the recessed portion of the upper dish-shaped body and adhered to the upper dish-shaped body at the recessed portion.

[0012] According to one embodiment of the present invention, the compressor for an ultra-low temperature refrigeration machine includes any of the above-mentioned oil separators.

[0013] Invention Effects

[0014] According to the present invention, the manufacturing cost of filter elements in oil separators can be reduced. Attached Figure Description

[0015] Figure 1 This is a diagram that roughly illustrates the cryogenic refrigerator involved in the implementation method.

[0016] Figure 2 This is a schematic cross-sectional view of the oil separator involved in the embodiment. Detailed Implementation

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, the same or equivalent constituent elements, components, and processes are labeled with the same symbols, and repeated descriptions are omitted where appropriate. For ease of explanation, scales or shapes of various parts are appropriately shown in the drawings, which are not intended to be limiting unless otherwise specified. The embodiments are merely examples and do not limit the scope of the present invention in any way. All features or combinations thereof described in the embodiments are not necessarily essential to the invention.

[0018] Figure 1 This is a diagram that roughly illustrates the cryogenic refrigerator involved in the implementation method.

[0019] The cryogenic refrigerator 10 includes a compressor 12 and a cold head 14. The compressor 12 is configured to recover refrigerant gas from the cold head 14, pressurize the recovered refrigerant gas, and supply it back to the cold head 14. The compressor 12 is also referred to as a compressor unit. The cold head 14 is also referred to as an expander, and it has a room temperature section 14a and a cryogenic section 14b (also referred to as a cooling platform). The compressor 12 and the cold head 14 constitute the refrigeration cycle of the cryogenic refrigerator 10, thereby cooling the cryogenic section 14b to the desired cryogenic temperature. The refrigerant gas is also referred to as the working gas, and helium is typically used, but other suitable gases may also be used.

[0020] As an example, the cryogenic refrigerator 10 is a single-stage or two-stage Gifford-McMahon (GM) refrigerator, but it can also be a pulse tube refrigerator, a Stirling refrigerator, or other types of cryogenic refrigerators. The cold head 14 has different configurations depending on the type of cryogenic refrigerator 10, but the compressor 12 can use a compressor with the following structure regardless of the type of cryogenic refrigerator 10.

[0021] Furthermore, the pressure of the refrigerant gas supplied from compressor 12 to cold head 14 and the pressure of the refrigerant gas recovered from cold head 14 to compressor 12 are typically much higher than atmospheric pressure, and can be referred to as the first high pressure and the second high pressure, respectively. For ease of explanation, the first high pressure and the second high pressure are simply referred to as high pressure and low pressure, respectively. Typically, the high pressure is, for example, 2 to 3 MPa. The low pressure is, for example, 0.5 to 1.5 MPa, and for example, approximately 0.8 MPa.

[0022] The compressor 12 includes a compressor body 16, an oil line 18, an oil separator 20, and an adsorber 21. Furthermore, the compressor 12 includes a discharge port 22, a suction port 24, a discharge flow path 26, a suction flow path 28, a storage tank 30, a bypass valve 32, a refrigerant gas cooling section 34, and an oil cooling section 36.

[0023] The compressor body 16 is configured to internally compress refrigerant gas drawn in through its suction port and discharge it through its discharge port. The compressor body 16 may be, for example, a scroll pump, a rotary pump, or another pump that pressurizes the refrigerant gas. The compressor body 16 may be configured to discharge a constant flow rate of refrigerant gas. Alternatively, the compressor body 16 may be configured to vary the flow rate of the discharged refrigerant gas. The compressor body 16 is sometimes also referred to as a compression chamber.

[0024] In the compressor body 16, oil is used for cooling and lubrication, and the refrigerant gas drawn in is directly exposed to this oil within the compressor body 16. Therefore, the refrigerant gas is discharged from the outlet with a small amount of oil mixed in.

[0025] The oil line 18 includes an oil circulation line 18a and an oil return line 18b. The oil circulation line 18a has an oil cooling section 36, and is configured such that oil flowing from the compressor body 16 is cooled by the oil cooling section 36 before flowing back into the compressor body 16. A throttling orifice is provided on the oil circulation line 18a to control the flow rate of oil passing through it. A filter for removing dust contained in the oil can also be provided on the oil circulation line 18a. To return the oil recovered by the oil separator 20 to the compressor body 16, the oil return line 18b connects the oil separator 20 to the suction flow path 28. A filter for removing dust contained in the oil separated in the oil separator 20 and a throttling orifice for controlling the amount of oil returning to the compressor body 16 can also be provided on the oil return line 18b.

[0026] The oil separator 20 is provided to separate oil that has mixed into the refrigerant gas as it passes through the compressor body 16. The oil separator 20 is connected to the discharge port of the compressor body 16 via the upstream portion 26a of the discharge flow path 26. Furthermore, the oil separator 20 is connected to the discharge port 22 via the downstream portion 26b of the discharge flow path 26. Details regarding the oil separator 20 will be described later.

[0027] The adsorber 21 is provided to remove residual components such as vaporized oil and other contaminants from the refrigerant gas. The adsorber 21 is located on the downstream portion 26b of the discharge flow path 26.

[0028] The discharge port 22 is the outlet for refrigerant gas in the compressor housing 38, provided for delivering refrigerant gas that has been pressurized to high pressure by the compressor body 16 from the compressor 12. The suction port 24 is the inlet for refrigerant gas in the compressor housing 38, provided for receiving low-pressure refrigerant gas into the compressor 12. The compressor housing 38 houses various components of the compressor 12, such as the compressor body 16 or the oil separator 20. The discharge port of the compressor body 16 is connected to the discharge port 22 via the discharge flow path 26, and the suction port 24 is connected to the suction port of the compressor body 16 via the suction flow path 28.

[0029] The storage tank 30 serves as a volume to remove pulsations contained in the low-pressure refrigerant gas returning from the cold head 14 to the compressor 12. The storage tank 30 is configured in the suction flow path 28.

[0030] The bypass valve 32 connects the discharge path 26 and the suction path 28 in a manner that bypasses the compressor body 16. As an example, the bypass valve 32 branches off from the downstream portion 26b of the discharge path 26 between the oil separator 20 and the adsorber 21, and connects to the suction path 28 between the compressor body 16 and the reservoir 30. The bypass valve 32 is provided to control the refrigerant gas flow rate and / or to equalize the pressure of the discharge path 26 and the suction path 28 when the compressor 12 is stopped.

[0031] The refrigerant gas cooling section 34 and the oil cooling section 36 constitute a cooling system that uses a cooling medium such as cooling water to cool the compressor 12. The refrigerant gas cooling section 34 is located upstream of the discharge flow path 26, at a distance of 26a, and is provided to cool the high-pressure refrigerant gas heated by the heat of compression generated during the compression of the refrigerant gas by the compressor body 16. The refrigerant gas cooling section 34 cools the refrigerant gas through heat exchange between the refrigerant gas and the cooling medium. Similarly, the oil cooling section 36 cools the oil through heat exchange between the oil flowing from the compressor body 16 and the cooling medium. The cooling medium is supplied to the compressor 12 from the outside, passes through the refrigerant gas cooling section 34 and the oil cooling section 36, and is then discharged to the outside of the compressor 12. Thus, the heat of compression generated in the compressor body 16 is discharged to the outside of the compressor 12 along with the cooling medium. Alternatively, the cooling medium can be cooled by a chiller (not shown) and then supplied again.

[0032] Furthermore, the cryogenic refrigerator 10 has a high-pressure port 40 and a low-pressure port 41 in the room temperature section 14a of the cold head 14. The high-pressure port 40 is connected to the discharge port 22 via a high-pressure pipe 42, and the low-pressure port 41 is connected to the suction port 24 via a low-pressure pipe 43.

[0033] Therefore, the refrigerant gas recovered from the cold head 14 to the compressor 12 flows from the low-pressure port 41 through the low-pressure piping 43 into the suction port 24 of the compressor 12. The refrigerant gas is recovered to the suction port of the compressor body 16 via the storage tank 30 on the suction flow path 28. The refrigerant gas is compressed and pressurized by the compressor body 16. The refrigerant gas output from the discharge port of the compressor body 16 passes through the refrigerant gas cooling section 34, oil separator 20, and adsorber 21 on the discharge flow path 26 and leaves the compressor 12 from the discharge port 22. The refrigerant gas is supplied to the interior of the cold head 14 via the high-pressure piping 42 and the high-pressure port 40.

[0034] Figure 2 This is a cross-sectional view that schematically shows the oil separator 20 according to the embodiment.

[0035] The oil separator 20 includes an oil separator container 44 and a filter element 46. The filter element 46 is disposed within the oil separator container 44 and defines an outer cavity 48 between itself and the oil separator container 44. Furthermore, the filter element 46 has an inner cavity 50 for introducing refrigerant gas and separates oil from the refrigerant gas flowing from the inner cavity 50 to the outer cavity 48.

[0036] The oil separator 20 is configured as a vertical oil separator. The oil separator 20 has an elongated cylindrical shape and is positioned within the compressor 12 such that its length direction is aligned with the vertical direction. Figure 1 The refrigerant gas (mixed with a small amount of oil) flowing into the compressor body 16 is introduced from the top of the oil separator 20. The refrigerant gas purified by the filter element 46 is discharged from the top of the oil separator 20 to the outside of the oil separator 20. The oil separated from the refrigerant gas by the filter element 46 flows vertically down inside or on the surface of the filter element 46 and is recovered from the bottom of the oil separator 20.

[0037] The oil separator container 44 is a cylindrical container that defines the shape of the oil separator 20, and it includes a container cylinder 44a, a container upper cover 44b, and a container lower cover 44c. The container upper cover 44b is fixed to the upper end of the container cylinder 44a, and the container lower cover 44c is fixed to the lower end of the container cylinder 44a. The container upper cover 44b and the container lower cover 44c are fixed to the container cylinder 44a, for example, by welding, thereby making the oil separator container 44 an airtight container.

[0038] A refrigerant gas inlet pipe 52, a refrigerant gas outlet pipe 54, and an oil return pipe 56 are provided on the container cover 44b. The refrigerant gas inlet pipe 52 is equivalent to... Figure 1 The upstream portion 26a of the discharge flow path 26 shown is connected to the oil separator 20. The refrigerant gas outlet pipe 54 corresponds to the downstream portion 26b of the discharge flow path 26, which is connected to the oil separator 20. The oil return pipe 56 corresponds to the portion of the oil return pipe 18b of the oil line 18, which is connected to the oil separator 20.

[0039] A refrigerant gas inlet pipe 52 is inserted from the top of the oil separator container 44 and introduces refrigerant gas into the oil separator container 44. The refrigerant gas inlet pipe 52 is configured to penetrate the container top cover 44b. The refrigerant gas inlet pipe 52 extends along the central axis of the oil separator 20. The refrigerant gas inlet pipe 52, penetrating the container top cover 44b, extends to the inner cavity 50 of the filter element 46, thereby communicating with the inner cavity 50. Through the refrigerant gas inlet pipe 52, refrigerant gas is introduced from the outside of the oil separator 20 into the inner cavity 50 of the filter element 46.

[0040] exist Figure 2 In the example shown, the refrigerant gas inlet pipe 52 extends to near the bottom of the inner cavity 50. Thus, when the front end 52a of the refrigerant gas inlet pipe 52 is located lower than half the height of the inner cavity 50, the amount of oil discharged from the refrigerant gas outlet pipe 54 that is not separated and recovered from the refrigerant gas in the oil separator 20 (also referred to as the oil rise) tends to be less compared to the case where the front end 52a of the refrigerant gas inlet pipe 52 is located higher than half the height of the inner cavity 50.

[0041] A refrigerant gas outlet pipe 54 is configured to penetrate the container cover 44b. The refrigerant gas outlet pipe 54, penetrating the container cover 44b, opens near the container cover 44b in the outer cavity 48 (e.g., between the container cover 44b and the filter element 46 in the axial direction of the oil separator 20). Refrigerant gas flowing from the inner cavity 50 through the filter element 46 into the outer cavity 48 is discharged from the refrigerant gas outlet pipe 54 to the outside of the oil separator 20.

[0042] The oil return pipe 56 is configured to penetrate the upper cover 44b of the container. The oil return pipe 56, penetrating the upper cover 44b, extends along the container cylinder 44a to the vicinity of the lower cover 44c. The oil return pipe 56 opens near the lower cover 44c in the outer cavity 48 (e.g., between the filter element 46 in the axial direction of the oil separator 20 and the lower cover 44c). Oil separated from the refrigerant gas by the filter element 46 is discharged from the oil return pipe 56 to the outside of the oil separator 20.

[0043] The filter element 46 includes a filter body 58 and a lower dish-shaped body 60 and an upper dish-shaped body 62 that clamp the filter body 58. The filter body 58 includes an inner cylinder component 58a, a filter component 58b, and an outer cylinder component 58c.

[0044] The lower dish-shaped body 60 is installed at the lower end of the filter body 58 and is joined to the bottom of the oil separator container 44 (e.g., the lower cover 44c). The upper dish-shaped body 62 is installed at the upper end of the filter body 58 and is joined to the refrigerant gas inlet pipe 52. The refrigerant gas inlet pipe 52 extends through the center of the upper dish-shaped body 62 toward the inner cavity 50. The upper dish-shaped body 62 and the lower dish-shaped body 60 are both disc-shaped components made of, for example, metal such as stainless steel.

[0045] The filter element 46 is engaged with the oil separator container 44 by fitting. Specifically, the lower dish-shaped body 60 has a first fitting portion 60a, and the bottom of the oil separator container 44 has a second fitting portion 64 that fits into the first fitting portion 60a. The first fitting portion 60a is formed in the lower dish-shaped body 60 as a recess that is recessed toward the inner cavity 50. The second fitting portion 64 is a protrusion that protrudes upward from the center of the lower cover 44c of the oil separator container 44.

[0046] The lower dish-shaped body 60 and the upper dish-shaped body 62 can be formed, for example, by stamping a metal sheet. The second fitting part 64 can be prepared as a separate component from the lower cover 44c of the oil separator container 44, and can be fixed to the lower cover 44c by, for example, by suitable methods such as thread fastening or spot welding. Alternatively, the second fitting part 64 can also be integrally formed with the lower cover 44c by cutting from the base material.

[0047] The upper dish-shaped body 62 is mounted on the upper end of the filter body 58 and has a recess 62a recessed towards the inner cavity 50. A refrigerant gas inlet pipe 52 is inserted into the inner cavity 50 through the recess 62a of the upper dish-shaped body 62 and is bonded to the upper dish-shaped body 62 in the recess 62a. An insertion hole for inserting the refrigerant gas inlet pipe 52 into the inner cavity 50 is formed on the bottom surface of the recess 62a, and an adhesive 66 is filled between the inserted refrigerant gas inlet pipe 52 and the side surface of the recess 62a. The adhesive 66 can be an epoxy-based adhesive or a silicone-based adhesive, or other sealing adhesive.

[0048] In this embodiment, the upper dish-shaped body 62 has the same shape as the lower dish-shaped body 60, except that the recess 62a of the upper dish-shaped body 62 has an insertion hole for the refrigerant gas inlet pipe 52. The lower dish-shaped body 60 can be used as the upper dish-shaped body 62 by providing a through hole in its first fitting portion 60a. Since the same parts as the lower dish-shaped body 60 can be used in the upper dish-shaped body 62, manufacturing costs can be reduced compared to designing each as a separate part.

[0049] The lower dish-shaped body 60 and the upper dish-shaped body 62 are respectively bonded to the upper and lower parts of the filter body 58 using an adhesive. Adhesive impregnation portions 68 are formed on the upper and lower parts of the filter component 58b. Similar to the adhesive 66 described above, this adhesive can also be an epoxy-based adhesive or a silicone-based adhesive, or other sealing adhesive. This prevents gaps from forming between the filter body 58 and the upper dish-shaped body 62, and between the filter body 58 and the lower dish-shaped body 60. It also prevents refrigerant gas introduced into the inner cavity 50 from the refrigerant gas inlet pipe 52, or oil separated and liquefied from the refrigerant gas, from flowing out into the outer cavity 48 in an oil-containing state through the gaps.

[0050] In the lower dish-shaped body 60, an annular groove serving as a tray for adhesive is formed between the outer edge 60b of the lower dish-shaped body 60 and the first fitting portion 60a. During the manufacturing stage, when uncured liquid adhesive is applied to this groove, the first fitting portion 60a functions as an inner dam to prevent adhesive from intruding into the inner cavity 50, and the outer edge 60b functions as an outer dam to prevent adhesive leakage to the outside. The end (lower end) of the filter body 58 is inserted into this adhesive tray, thereby bonding the filter body 58 to the lower dish-shaped body 60. Therefore, as... Figure 2 As shown, the height of the first fitting portion 60a (and the height of the outer edge 60b) in the axial direction (up and down direction in the figure) of the oil separator 20 is higher than the height of the adhesive impregnation portion 68. Furthermore, the adhesive impregnation portion 68 is radially sandwiched between the first fitting portion 60a and the outer edge 60b.

[0051] In addition, by setting the height of the first fitting portion 60a in the axial direction to be equal to or slightly higher than the height of the outer edge 60b, the intrusion of adhesive into the inner cavity 50 can be more reliably suppressed.

[0052] Similarly, in the upper dish-shaped body 62, an annular groove that serves as a tray for adhesive is also formed between the outer edge 62b and the recess 62a. By applying adhesive to this groove and inserting the filter body 58 into it, the filter body 58 is bonded to the upper dish-shaped body 62.

[0053] The inner cylinder component 58a of the filter body 58 is, for example, a cylindrical component formed from a perforated plate made of stainless steel or carbon steel. The inner cylinder component 58a is coaxially arranged with the central axis of the oil separator 20 to surround the refrigerant gas outlet pipe 54. The inner cylinder component 58a is provided to support the filter component 58b from the inside. The internal space of the inner cylinder component 58a is an inner cavity 50, which is surrounded by the inner cylinder component 58a, the upper dish-shaped body 62, and the lower dish-shaped body 60.

[0054] The filter component 58b has a cylindrical shape and surrounds the inner cavity 50. The filter component 58b is also coaxially arranged with the central axis of the oil separator 20. The filter component 58b is formed by winding filter material around the inner cylinder component 58a in a cylindrical shape with the inner cylinder component 58a as the core. The filter component 58b occupies most of the volume of the filter body 58. The filter component 58b is formed, for example, from mineral fibers such as glass fiber or other filter materials.

[0055] The outer cylinder component 58c is, for example, a cylindrical component formed from a perforated plate of stainless steel or carbon steel, and is coaxially arranged with the central axis of the oil separator 20 to surround the filter component 58b. The outer side of the outer cylinder component 58c is adjacent to the outer cavity 48. The outer cylinder component 58c reinforces the filter component 58b from the outside, and the inner cylinder component 58a reinforces the filter component 58b from the inside. In addition, the inner cylinder component 58a and the outer cylinder component 58c do not necessarily have to be perforated plates; any structure that does not obstruct gas flow and supports the filter component 58b can be used, such as wire mesh, plates with slits, or components with bars arranged in a grid pattern.

[0056] exist Figure 2 In the diagram, for ease of understanding, the white arrow G represents the flow of refrigerant gas within the oil separator 20, and the dark arrow OL represents the flow of oil. The refrigerant gas mixed with oil (G, OL) flows from the refrigerant gas inlet pipe 52 into the inner cavity 50 of the filter element 46. It is separated into refrigerant gas G and oil OL by the filter body 58. Refrigerant gas G is transported from the oil separator 20 through the refrigerant gas outlet pipe 54. Oil OL flows to the bottom of the oil separator container 44 and is recovered through the oil return pipe 56.

[0057] In conventional oil separators, the filter element is suspended and supported only by the refrigerant gas inlet pipe within the oil separator container. Therefore, during the assembly or transport of the oil separator to the application site, the filter element may be subjected to strong external forces, causing it to vibrate within the oil separator container or collide with the side of the container.

[0058] To avoid this situation, additional reinforcing components can be added to the oil separator. For example, reinforcing ribs protruding radially outward from the side of the filter element toward the side of the oil separator container can be installed on the filter element, or reinforcing ribs protruding from the side of the oil separator container toward the side of the filter element can be installed on the oil separator container to limit the displacement of the filter element caused by vibration.

[0059] Alternatively, if the pressure loss of the gas passing through the filter element becomes excessive for some reason, the filter element may be subjected to axial loads. To resist such loads, a support rod can be provided that connects the upper and lower ends of the filter element axially.

[0060] However, such anti-vibration or load-response measures increase the number of parts in the oil separator, thus leading to increased manufacturing costs.

[0061] In the oil separator 20 according to the embodiment, the filter element 46 has a lower dish-shaped body 60 installed at its lower end. The oil separator container 44 is joined to the lower dish-shaped body 60 at its bottom. To achieve this joining, the lower dish-shaped body 60 has a first fitting portion 60a, and the bottom of the oil separator container 44 has a second fitting portion 64 that fits into the first fitting portion 60a.

[0062] In this way, the filter element 46 is supported not only by the refrigerant gas inlet pipe 52 at its upper end, but also at its lower end by the engagement between the first fitting portion 60a and the second fitting portion 64. This suppresses vibrations that may occur in the filter element 46 and resists axial loads that may occur in the filter element 46. Compared to the case where additional components such as reinforcing ribs or support rods are added, this method achieves anti-vibration countermeasures with a simple structure, thereby reducing manufacturing costs.

[0063] Furthermore, in the oil separator 20 according to the embodiment, the filter element 46 has an upper dish-shaped body 62 mounted on its upper end and having a recess 62a recessed toward the inner cavity 50. The refrigerant gas inlet pipe 52 is inserted into the inner cavity 50 through the recess 62a of the upper dish-shaped body 62 and is bonded to the upper dish-shaped body 62 through the recess 62a.

[0064] In conventional oil separators, the refrigerant gas inlet pipe is often welded to the upper end of the filter element. This requires additional components, such as a welding auxiliary plate at the upper end of the filter element. However, in this embodiment, the refrigerant gas inlet pipe 52 can be bonded to the upper dish-shaped body 62, eliminating the need for such additional components. Therefore, manufacturing costs can be reduced.

[0065] Furthermore, if welding is used, it becomes an additional process different from bonding. In contrast, bonding the refrigerant gas inlet pipe 52 to the upper dish-shaped body 62 and drying the adhesive can be performed simultaneously with bonding the filter component 58b to the lower dish-shaped body 60 and the upper dish-shaped body 62 and drying the adhesive. This also reduces manufacturing costs.

[0066] Furthermore, by combining the bonding of the refrigerant gas inlet pipe 52 to the upper dish-shaped body 62 and the engagement of the lower end of the filter element 46 with the bottom of the oil separator container 44, stress concentration in the adhesive 66 can be suppressed.

[0067] Furthermore, in the oil separator 20 according to the embodiment, the first fitting portion 60a is formed in the lower dish-shaped body 60 as a recessed portion facing the inner cavity 50. In this case, it is easy to configure the front end 52a of the refrigerant gas inlet pipe 52 close to the bottom of the oil separator 20. As described above, this improves the oil separation performance of the oil separator 20.

[0068] Assuming the lower dish-shaped body 60 is flat without the first fitting portion 60a, when the filter body 58 is pressed against the lower dish-shaped body 60 for bonding, the filter body 58 will squeeze a portion of the adhesive into the inner cavity 50, causing the adhesive to bulge within the inner cavity 50. If the front end 52a of the refrigerant gas inlet pipe 52 is positioned sufficiently close to the bottom of the inner cavity 50, the bulging adhesive may reach the front end 52a, potentially blocking it. Thus, when the surface opposite the front end 52a is covered with adhesive, the distance between this opposing surface (i.e., the surface of the cured adhesive) and the front end 52a depends on the amount of adhesive applied or the bonding method. The front end 52a needs to be positioned upwards to prevent it from reaching the adhesive. If the front end 52a is far from the bottom of the inner cavity 50, it may affect the performance of the oil separator 20.

[0069] However, in this embodiment, the front end 52a of the refrigerant gas inlet pipe 52 is opposite to the first fitting portion 60a, and the height of the first fitting portion 60a is higher than the adhesive impregnation portion 68. Therefore, the upper surface of the first fitting portion 60a opposite to the front end 52a is not covered by adhesive and is exposed to the inner cavity 50. Since adhesive is excluded from the upper surface of the first fitting portion 60a opposite to the front end 52a, the front end 52a can be configured closer to the bottom of the inner cavity 50, which, as described above, improves the performance of the oil separator 20.

[0070] A positioning portion 52b may be provided on the refrigerant gas inlet pipe 52. The positioning portion 52b protrudes radially outward from the outer peripheral surface of the refrigerant gas inlet pipe 52. The positioning portion 52b may be formed in the form of a flange on the entire circumference of the refrigerant gas inlet pipe 52. By simply abutting the positioning portion 52b against the recess 62a, the front end 52a can be easily positioned at a predetermined distance separated from the upper surface of the first fitting portion 60a.

[0071] Furthermore, the positioning part 52b is not limited to a specific shape. For example, the refrigerant gas inlet pipe 52 can be formed with a large diameter at the top and a small diameter at the bottom, and the step between these large-diameter and small-diameter parts can abut against the recess 62a of the upper dish-shaped body 62.

[0072] The present invention has been described above with reference to embodiments. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and various design changes and modifications are possible, and such modifications are also within the scope of the present invention. Various features described in one embodiment may also be applicable to other embodiments. New embodiments resulting from combinations possess the effects of each of the combined embodiments.

[0073] In the above embodiment, the second fitting portion 64 is a cylindrical protrusion protruding from the lower cover 44c of the container, but the second fitting portion 64 may also have other shapes. For example, the second fitting portion 64 may also have a large-diameter portion protruding from the lower cover 44c of the container and a small-diameter portion protruding further from the large-diameter portion, and the small-diameter portion fitting with the first fitting portion 60a. The upper surface of the large-diameter portion may contact the lower surface of the lower dish-shaped body 60 around the first fitting portion 60a and support the filter element 46.

[0074] The mating position between the lower dish-shaped body 60 and the lower cover 44c of the container is not limited to the center of the lower dish-shaped body 60, but can also be located on the outer periphery of the lower dish-shaped body 60. For example, a first mating portion 60a can be formed in the lower dish-shaped body 60 further outward than the inner cavity 50, recessed towards the filter component 58b. The second mating portion 64 can also be a protrusion protruding upward from the position of the lower cover 44c of the oil separator container 44 corresponding to the first mating portion 60a.

[0075] In the above embodiment, the first fitting portion 60a is a concave portion and the second fitting portion 64 is a convex portion. However, conversely, the first fitting portion 60a may be a convex portion and the second fitting portion 64 may be a concave portion. The first fitting portion 60a may be a convex portion protruding from the lower dish-shaped body 60 toward the lower cover 44c of the container, and the second fitting portion 64 may be a concave portion formed in the lower cover 44c of the container.

[0076] The engagement between the lower part of the filter element 46 and the bottom of the oil separator container 44 is not limited to a mating structure. For example, the engagement between the lower part of the filter element 46 and the bottom of the oil separator container 44 can also be a structure based on the contact between the lower surface of the filter element 46 (e.g., the lower dish 60) and the bottom surface of the oil separator container 44 (e.g., the lower cover 44c of the container), as long as these can be secured to each other.

[0077] The present invention has been described above with reference to specific embodiments and specific statements. However, the embodiments are only one aspect of the principle and application of the present invention. Various modifications or configuration changes are allowed in the embodiments without departing from the spirit of the present invention as defined in the technical solution.

[0078] Industrial availability

[0079] This invention can be applied to the fields of oil separators and compressors for cryogenic refrigeration machines.

[0080] Symbol Explanation

[0081] 10-Cryogenic refrigerator, 12-Compressor, 20-Oil separator, 44-Oil separator container, 46-Filter element, 48-Outer cavity, 50-Inner cavity, 52-Refrigerant gas inlet pipe, 60-Lower dish-shaped body, 62-Upper dish-shaped body.

Claims

1. An oil separator characterized by, have: Oil separator container; A refrigerant gas inlet pipe is inserted from the top of the oil separator container and introduces refrigerant gas into the oil separator container; and A filter element is disposed within the oil separator container, and an outer cavity is defined between the filter element and the oil separator container. The filter element has an inner cavity connected to and through a refrigerant gas inlet pipe, allowing refrigerant gas to enter from the refrigerant gas inlet pipe. The filter element separates oil from the refrigerant gas flowing from the inner cavity to the outer cavity. The filter element includes a lower dish-like body mounted at its lower end, and the oil separator container is joined to the lower dish-like body at its bottom. The filter element includes an upper dish-shaped body mounted on its upper end and having a recessed portion facing the inner cavity. The refrigerant gas inlet pipe has a positioning part that abuts against the recess of the upper dish-shaped body, thereby positioning the front end of the refrigerant gas at a predetermined distance from the lower dish-shaped body. The refrigerant gas inlet pipe is inserted from the recess of the upper dish-shaped body into the inner cavity and adheres to the upper dish-shaped body in the recess.

2. The oil separator according to claim 1, characterized in that, The lower dish-shaped body has a first fitting portion, and the bottom of the oil separator container has a second fitting portion that fits into the first fitting portion.

3. The oil separator according to claim 2, characterized in that, The first fitting portion is formed in the lower dish-shaped body as a recessed portion that is recessed toward the inner cavity.

4. The oil separator according to claim 3, characterized in that, The second fitting portion has a protrusion that protrudes from the lower cover of the oil separator container toward the recess of the lower dish-shaped body.

5. The oil separator according to any one of claims 2 to 4, characterized in that, The second fitting portion contacts the lower surface of the lower plate-shaped body around the first fitting portion and supports the filter element.

6. The oil separator according to any one of claims 2 to 4, characterized in that, The filter element includes a filter body with an adhesive impregnation portion at the lower end. The lower dish-shaped body has an outer edge forming an annular groove between itself and the first fitting portion, and the adhesive impregnation portion is accommodated in the annular groove.

7. The oil separator according to claim 6, characterized in that, The height of the first fitting portion and the outer edge of the lower dish-shaped body is higher than the height of the adhesive-impregnated portion.

8. A compressor for an ultra-low temperature refrigeration machine, characterized in that, An oil separator comprising any one of claims 1 to 7.

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