Patent Application
20210332818
The present invention relates to a compressor for a refrigerating machine.
Refrigerating machines are devices for controlling the target temperature, among which are included a wide range of machines such as freezers, refrigerators, air conditioners, ocean shipping containers, water heaters, and radiators. A refrigerating machine includes a refrigerant circuit in which a compressor for compressing the refrigerant is installed. Patent Literature 1 (Japanese Patent Application Laid-open Publication No. 2002-303272) discloses a compressor used in an ocean shipping container.
Compressors used for ocean shipping are required to have high durability. Motors, in particular, which are required to meet stringent durability requirements, are often disposed in a space in the casing that is filled with a low-temperature, low-pressure gas refrigerant, so as to be cooled when generating heat. For this reason, the compressors adopt a so-called low-pressure dome structure in which the low-pressure gas refrigerant is contained in most of the internal space of the casing.
During operation of one such compressor, dew condensation occurs on the outer surface of the region of the casing that covers the space containing the low-temperature, low-pressure gas refrigerant. The condensed moisture freezes. The ice on the outer surface of the casing melts after the operation of the compressor is stopped. As a result of repeated freezing and melting of the moisture, the protective coating applied to the outer surface of the casing undergoes stress, which may result in damaged portions such as cracks, tears, and holes. Subsequently, the moisture and the like contained in the outside air pass through these damaged portions and come into contact with the base metal of the casing which is made of iron or the like. This causes corrosion in the base metal.
An object of the present invention is to reduce the occurrence of corrosion of the casing in a compressor for a refrigerating machine.
A compressor according to a first aspect of the present invention includes a casing, a compression mechanism, and a motor. The casing is configured to cover an internal space. The internal space includes a first space and a second space larger than the first space. The casing includes a first casing part covering the first space and a second casing part covering the second space. The compression mechanism generates a high-pressure fluid by compressing a low-pressure fluid. The motor drives the compression mechanism. The first space and the second space are each a high-pressure space configured to contain the high-pressure fluid, or the second space is the high-pressure space and the first space is a low-pressure space configured to contain the low-pressure fluid. A metallic coating is formed on an outer surface of at least the first casing part.
According to this configuration, most of the casing covers the high-pressure space. Unlike the low-pressure fluid, the high-pressure fluid contained in the high-pressure space has a high temperature. Therefore, an outer surface of the casing is less likely to freeze, and consequently the occurrence of corrosion of the casing is reduced.
A compressor according to a second aspect of the present invention is the compressor according to the first aspect, wherein the metallic coating is also formed on an outer surface of the second casing part.
According to this configuration, the metallic coating is formed on the entire outer surface of the casing. Therefore, it becomes more difficult for moisture and the like to reach the base metal of the casing, further reducing the occurrence of corrosion.
A compressor according to a third aspect of the present invention is the compressor according to the first aspect or the second aspect, wherein the metallic coating is a metal-sprayed coating. The metal-sprayed coating is in contact with the casing.
According to this configuration, the metal-sprayed coating is formed on the casing. Therefore, portions of the casing that have complicated shapes are easily protected from moisture and the like.
A compressor according to a fourth aspect of the present invention is the compressor according to any one of the first aspect to the third aspect, wherein the casing is composed of a first metal. The metallic coating is composed of a second metal having an ionization tendency greater than that of the first metal.
According to this configuration, the metallic coating has an ionization tendency greater than that of the casing. In a case where moisture intrudes from holes or the like of the metallic coating and reaches the casing, the metallic coating tends to corrode prior to the casing. Therefore, the occurrence of corrosion of the casing is further reduced.
A compressor according to a fifth aspect of the present invention includes a casing, a compression mechanism, and a motor. The casing is configured to cover an internal space. The internal space includes a first space and a second space larger than the first space. The casing includes a first casing part covering the first space and a second casing part covering the second space. The compression mechanism generates a high-pressure fluid by compressing a low-pressure fluid. The motor drives the compression mechanism. Both the first space and the second space are high-pressure spaces configured to contain the high-pressure fluid. A resin coating is formed on an outer surface of the casing.
According to this configuration, substantially the entire region of the casing covers the high-pressure space. Unlike the low-pressure fluid, the high-pressure fluid contained in the high-pressure space has a high temperature. For this reason, the outer surface of the casing is less likely to freeze. Moreover, the resin coating protects the casing from moisture attached to the outer surface of the casing. For this reason, the occurrence of corrosion of the casing is reduced.
A compressor according to a sixth aspect of the present invention is the compressor according to any one of the first aspect to the fifth aspect, wherein the compression mechanism at least faces the first space. The motor is disposed in the second space.
According to this configuration, the motor with a fixed volume is disposed in the second space. Therefore, the area of low temperature on the outer surface of the casing can be made smaller than when the motor is disposed in the first space. For this reason, the outer surface is less likely to freeze.
A compressor according to a seventh aspect of the present invention is the compressor according to any one of the first aspect to the sixth aspect, wherein the casing is provided with a suction port configured to suction the low-pressure fluid. The compression mechanism includes a compression chamber that does not belong to either the first space or the second space. The suction port is configured to be communicated with the compression chamber.
According to this configuration, the low-temperature, low-pressure gas refrigerant to be suctioned into the compressor flows directly into the compression chamber without drifting in the internal space of the casing. Therefore, since the portions in the casing with which the low-temperature, low-pressure gas refrigerant comes into contact are extremely limited, freezing of the outer surface of the casing can be reduced effectively.
A compressor according to an eighth aspect of the present invention is the compressor according to any one of the first aspect to the seventh aspect, wherein the compression mechanism includes a fixed scroll and a movable scroll. The fixed scroll is fixed directly or indirectly to the casing. The movable scroll is configured to revolve with respect to the fixed scroll.
According to this configuration, the compressor is a scroll compressor. Thus, the output of the compressor in which the occurrence of corrosion of the casing is reduced can be increased.
A freezing and refrigeration container unit for marine transportation according to a ninth aspect of the present invention includes a container, a utilization heat exchanger, a heat source heat exchanger, a first refrigerant flow path, a second refrigerant flow path, a decompression device, and a compressor. The container is configured to contain articles. The utilization heat exchanger is disposed inside the container. The heat source heat exchanger is disposed outside the container. The first refrigerant flow path and the second refrigerant flow path are each configured to move a refrigerant between the utilization heat exchanger and the heat source heat exchanger. The decompression device is provided in the first refrigerant flow path. The compressor is provided in the second refrigerant flow path. The compressor is the one described in any one of the first aspect to the eighth aspect.
According to this configuration, the compressor mounted in the freezing and refrigeration container unit for marine transportation can reduce corrosion of the casing.
A manufacturing method according to a tenth aspect of the present invention is for manufacturing the compressor according to any one of the first aspect to the fourth aspect. The manufacturing method includes a step of preparing the casing, and a step of forming the metallic coating by thermally spraying the outer surface of at least the first casing part of the casing with a metal.
According to this method, the outer surface of at least the first casing part is thermally sprayed with a metal. Since the metallic coating is formed on the first casing part, a compressor less likely to corrode can be manufactured.
According to the compressor of the present invention, the occurrence of corrosion of the casing is reduced.
According to the freezing and refrigeration container unit for marine transportation of the present invention, with the compressor mounted therein, the occurrence of corrosion of the casing can be reduced.
According to the manufacturing method of the present invention, a compressor less likely to corrode can be manufactured.
Embodiments of the compressor and the like according to the present invention are described hereinafter with reference to the drawings. Note that the specific configurations of the compressor and the like according to the present invention are not limited to the following embodiments and can be changed appropriately without departing from the gist of the present invention.
The freezing and refrigeration container unit 1 for marine transportation includes a base plate 2, a container 3, and a refrigerant circuit 4. The container 3 is installed on the base plate 2 and configured to contain the articles. The refrigerant circuit 4 is configured to cool an internal space of the container 3.
The refrigerant circuit 4 includes a heat source heat exchanger 7a, a utilization heat exchanger 7b, a first refrigerant flow path 8, a second refrigerant flow path 6, a decompression device 9, and the compressor 5A.
The heat source heat exchanger 7a is disposed outside the container 3. The heat source heat exchanger 7a exchanges heat between the outside air and a refrigerant by functioning as a heat radiator for the refrigerant, typically a refrigerant condenser.
The utilization heat exchanger 7b is disposed inside the container 3. The utilization heat exchanger 7b exchanges heat between the air inside the container 3 and the refrigerant by functioning as a heat absorber for the refrigerant, typically a refrigerant evaporator.
The first refrigerant flow path 8 is a flow path configured to move the refrigerant between the utilization heat exchanger 7b and the heat source heat exchanger 7a. The first refrigerant flow path 8 includes a second pipeline 8a and a third pipeline 8b.
The second refrigerant flow path 6 is a flow path configured separately from the first refrigerant flow path 8 so as to move the refrigerant between the utilization heat exchanger 7b and the heat source heat exchanger 7a. The second refrigerant flow path 6 includes a first pipeline 6a and a fourth pipeline 6b.
The decompression device 9 is a device for decompressing the refrigerant and is composed of, for example, an expansion valve. The decompression device 9 is provided in the first refrigerant flow path 8. Specifically, the decompression device 9 is provided between the second pipeline 8a and the third pipeline 8b. The decompression device 9 may be located on the outside or inside of the container 3.
The compressor 5A is a device for compressing a low-pressure gas refrigerant, which is a fluid, to generate a high-pressure gas refrigerant, which is also a fluid. The compressor 5A functions as a cold source in the refrigerant circuit 4. The compressor 5A is provided in the second refrigerant flow path 6. Specifically, the compressor 5A is provided between the first pipeline 6a and the fourth pipeline 6b. The compressor 5A may be located on the inside of the container 3, but in most cases the compressor 5A is located on the outside of the container 3.
In typical basic operations of the refrigerant circuit 4 described hereinafter, the heat source heat exchanger 7a functions as a refrigerant condenser, and the utilization heat exchanger 7b functions as a refrigerant evaporator. However, depending on the type of the refrigerant used or other conditions, the basic operations of the refrigerant circuit 4 are not limited to these.
As shown in
The casing 10 is configured to contain, in an internal space 70 thereof, the motor 20, the crankshaft 30, the compression mechanism 40, the upper bearing holding member 61, and the lower bearing holding member 62. The casing 10 includes a casing body part 11, a casing upper part 12, and a casing lower part 13, which are welded together airtight. The casing 10 is strong enough to withstand the pressure of the refrigerant filling the internal space 70.
The casing upper part 12 is provided with a suction port 15a, and a suction pipe 15 for suctioning the refrigerant is inserted into the suction port 15a and fixed airtight thereto by welding. The casing body part 11 is provided with a discharge port 16a, and a discharge pipe 16 for discharging the refrigerant is inserted into the discharge port 16a and fixed airtight thereto by welding. An oil reservoir 14 for storing a refrigeration oil is provided in the lower part of the internal space 70 of the casing 10. A support part 17 for supporting the casing 10 upright is welded to the casing lower part 13.
The internal space 70 of the casing is divided into a first space 71 and a second space 72 by a partition member 65 and other parts. The first space 71 is a low-pressure space configured to be filled with the low-pressure gas refrigerant. The second space 72 is a high-pressure space configured to be filled with the high-pressure gas refrigerant. The second space 72 has a volume greater than that of the first space 71.
The motor 20 receives a supply of electricity to generate power. The motor 20 has a stator 21 and a rotor 22. The stator 21 is fixed to the casing 10 and has a coil, not shown, for generating a magnetic field. The rotor 22 is configured to be rotatable with respect to the stator 21 and has a permanent magnet, not shown, for magnetically interacting with the coil. The motor 20 is disposed in the second space 72.
The temperature of the high-pressure gas refrigerant filling the second space 72 is high. Therefore, placing the motor 20, which is a heat-generating component, in the second space 72 has been avoided in the past. However, motors available in the market recently have been improved, among which some do not generate as much heat as before. The inventor of the present invention has discovered that it is now possible to place the motor 20 in the second space 72.
The crankshaft 30 transmits the power generated by the motor 20. The crankshaft 30 includes a concentric part 31 and an eccentric part 32. The concentric part 31 has a shape concentric with the rotation axis of the rotor 22 and is fixed together with the rotor 22. The eccentric part 32 is eccentric with respect to the rotation axis of the rotor 22. When the concentric part 31 rotates together with the rotor 22, the eccentric part 32 moves in a circle.
The compression mechanism 40 is a mechanism for compressing the low-pressure gas refrigerant to generate the high-pressure gas refrigerant. The compression mechanism 40 is driven by the power transmitted by the crankshaft 30. The compression mechanism 40 includes a fixed scroll 41 and a movable scroll 42. The fixed scroll 41 is fixed directly or indirectly to the casing 10. For example, the fixed scroll 41 is fixed indirectly to the casing body part 11 via the upper bearing holding member 61 described hereinafter. The movable scroll 42 is configured to be able to revolve with respect to the fixed scroll 41. The eccentric part 32 of the crankshaft 30 is fitted to the movable scroll 42 together with a bearing. As the eccentric part 32 moves in a circle, the movable scroll 42 revolves with power.
The fixed scroll 41 and the movable scroll 42 each have an end plate and a spiral wrap standing upright on the end plate. Several spaces surrounded by the end plates and the wraps of the fixed scroll 41 and the movable scroll 42 are compression chambers 43. When the movable scroll 42 revolves, one compression chamber 43 gradually reduces the volume thereof while moving from the peripheral portion to the central portion. In this process, the low-pressure gas refrigerant contained in the compression chamber 43 is compressed into the high-pressure gas refrigerant. The high-pressure gas refrigerant is discharged from a discharge port 45 provided in the fixed scroll 41 to a chamber 72a located outside the compression mechanism 40, and then passes through a high-pressure passage 72b. The chamber 72a and the high-pressure passage 72b each constitute a part of the second space 72. The high-pressure gas refrigerant in the second space 72 is eventually discharged from the discharge pipe 16 to the outside of the compressor 5A.
The compression mechanism 40 as a whole may function to divide the first space 71 and the second space 72 from each other in cooperation with the partition member 65.
The upper bearing holding member 61 holds a bearing. The upper bearing holding member 61 rotatably supports the upper side of the concentric part 31 of the crankshaft 30 via the bearing. The upper bearing holding member 61 is fixed to an upper part of the casing body part 11. The upper bearing holding member 61 may function to divide the first space 71 and the second space 72 from each other in cooperation with the partition member 65.
The lower bearing holding member 62 holds a bearing. The lower bearing holding member 62 rotatably supports the lower side of the concentric part 31 of the crankshaft 30 via the bearing. The lower bearing holding member 62 is fixed to a lower part of the casing body part 11.
For the purpose of protecting the compressor 5A, a protective coating 50 is provided on at least part of the casing 10, the suction pipe 15, the discharge pipe 16, the support part 17, the terminal guard 18, the terminal cover 19, and other parts (collectively referred to as “base metal,” hereinafter).
While the base metal is composed of a first metal, the protective coating 50 is a metallic coating 50A composed of, for example, a second metal different from the first metal. It is preferred that the second metal be a so-called less-noble metal having an ionization tendency greater than that of the first metal. The first metal is, for example, iron. The second metal is, for example, aluminum, magnesium, zinc, or an alloy containing any of these metals. Moreover, the metallic coating 50A used as the protective coating 50 may be made of a material obtained by mixing ceramics with the second metal.
Since the low-temperature, low-pressure gas refrigerant comes into contact with the first casing part 10a, moisture attached to the first casing part 10a tends to freeze. As the compressor 5A is repeatedly operated and stopped, freezing and melting of the moisture occur alternately in the first casing part 10a, and the metallic coating 50A is liable to be damaged by stress caused by such freezing and melting. For this reason, the possibility of corrosion of the base metal at the first casing part 10a is relatively high.
Since the high-temperature, high-pressure gas refrigerant comes into contact with the second casing part 10b, moisture attached to the second casing part 10b is less likely to freeze. Thus, the possibility of corrosion of the base metal at the second casing part 10b is relatively low.
The metallic coating 50A can be formed by various methods such as thermal spraying, vacuum deposition, sputtering, plating, and pasting of rolled metal foil. In a case where a metal-sprayed coating formed by thermal spraying is adopted as the metallic coating 50A, the average thickness of the metallic coating 50A can easily be changed depending on the part of the base metal. The metal-sprayed coating, the average thickness of which is controlled in accordance with the likeliness of corrosion of the abovementioned part of the base plate, has a structure and ability to reduce corrosion of this part of the base metal over a long period of time. In addition, although the metal-sprayed coating sometimes has the properties of a porous material, the average thickness of the metal-sprayed coating can be controlled and made thick to the extent that performance of the protective coating is not impaired by such properties. Furthermore, since the position, angle, and moving speed of the spray head of a thermal sprayer can be adjusted relatively freely, the metal-sprayed coating can easily be formed even on portions on the base metal that have complicated shapes.
An example of the method for manufacturing the compressor 5A having a metal-sprayed coating as the metallic coating 50A is now described hereinafter.
The compressor 5A, which does not yet have the protective coating 50 formed thereon, is prepared. Basic assembly of the compressor 5A is completed. Various parts and the refrigeration oil are contained in the casing 10. An anti-rust oil is applied to a surface of the base metal such as the casing 10, in order to prevent rust from forming during the storage life.
For the purpose of achieving stronger adhesion of the metallic coating 50A to be formed to the base metal, a degreasing process for removing the anti-rust oil from the base metal is performed.
Masking is performed on portions where the metallic coating 50A is preferably not formed. The portions to be masked include, for example, the terminal 64, bolt holes formed in the base metal, and the like.
For the purpose of achieving stronger adhesion of the metallic coating 50A, a blasting process is performed to make the surface of the base metal rough. As a result of the blasting process, oxide films, scales, and other deposits on the surface of the base metal are removed. It is preferred that the shape of the surface of the base metal after the blasting process be sharp. For this reason, as a shot blasting material used in the blasting process, sharp particles are preferred over spherical particles. It is preferred that the shot blasting material be alumina having hardness.
A process for applying a rough surface forming agent to the surface of the base metal may be performed in place of the blasting process.
The base metal is heated in order to evaporate and remove the moisture and the like on the surface of the base metal. As a result, adhesion of the metallic coating 50A to the base metal is further improved. The temperature of the surface of the base metal preferably does not exceed, for example, 150° C. Accordingly, damage to various parts and deterioration of the refrigeration oil can be restrained.
A thermal spraying process for spraying the surface of the base metal with a flowable material is performed. It is preferred that the thermal spraying process be performed within four hours after the blasting process. Otherwise, the adhesion between the metallic coating 50A and the base metal drops due to a decrease in surface activity, adhesion of moisture, and the like.
As described above, a mixture of the second metal and ceramics may be used as the flowable material instead of using the second metal. Alternatively, a ceramics-sprayed coating may be formed on the metal-sprayed coating composed of the second metal, and then a plurality of layers of protective coating 50 may be formed thereon. Depending on the type of the flowable material, an appropriate thermal spraying method is selected from among flame spraying, are spraying, plasma spraying, and the like.
The thickness of the metal-sprayed coating to be formed is controlled by adjusting the spraying time, the angle and moving speed of the spray head of the thermal sprayer, and other conditions. In a case where an edge is present in the base metal, the thickness of the metal-sprayed coating at the portion of the edge tends to be smaller than an intended thickness. For this reason, it is preferred that the base metal be chamfered prior to the execution of the thermal spraying process.
In order to reliably reduce corrosion of the base metal, a sealing process for closing holes present in the formed metal-sprayed coating is performed. In the sealing process, a sealing agent is applied to the metal-sprayed coating with a brush. Alternatively, the sealing agent may be sprayed onto the metal-sprayed coating. Alternatively, the base metal having the metal-sprayed coating may be immersed in a tank of sealing agent.
Examples of the scaling agent include, for example, silicon resin, acrylic resin, epoxy resin, urethane resin, and fluorine resin. The sealing agent may contain metallic flake. In this case, a labyrinth seal is formed in the holes of the metal-sprayed coating, reducing the moisture permeability of the metal-sprayed coating.
The sealing process is performed within twelve hours at most, or preferably five hours, after the thermal spraying process. Otherwise, moisture adhesion and the like may occur, preventing the sealing agent from penetrating easily. As with the thermal spraying process, it is preferred that the base metal be heated in advance in performing the sealing process.
In order to further improve anticorrosion performance or to improve the appearance of the compressor 5A, painting may be performed.
(7-1)
Most of the casing 10 covers the second space 72. Unlike the low-pressure fluid, the high-pressure fluid contained in the second space 72 has a high temperature. Therefore, the outer surface of the casing 10 is less likely to freeze, and consequently the occurrence of corrosion of the outer surface of the casing 10 is reduced.
(7-2)
The metallic coating 50A is formed on the entire outer surface of the casing 10.
Therefore, it becomes more difficult for moisture and the like to reach the casing 10, further reducing the occurrence of corrosion.
(7-3)
A metal-sprayed coating is formed on the casing 10. Therefore, portions of the casing that have complicated shapes are easily protected from moisture and the like.
(7-4)
The metallic coating 50A has an ionization tendency greater than that of the casing 10. In a case where moisture intrudes from holes or the like of the metallic coating 50A and reaches the casing 10, the metallic coating 50A tends to corrode prior to the casing 10. In other words, the metallic coating 50A has a function of sacrificial protection. Therefore, the occurrence of corrosion of the casing 10 is further reduced.
(7-5)
The motor 20 with a fixed volume is disposed in the second space 72. Therefore, the area of low temperature on the outer surface of the casing 10 can be made smaller than when the motor 20 is disposed in the first space 71. For this reason, the outer surface of the casing is less likely to freeze.
(7-6)
The compressor 5A is a scroll compressor. Thus, the output of the compressor in which the occurrence of corrosion of the casing 10 is reduced can be increased.
(7-7)
The compressor 5A mounted in the freezing and refrigeration container unit 1 for marine transportation can reduce corrosion of the casing 10.
(7-8)
The outer surface of at least the first casing part 10a is thermally sprayed with a metal. Since the metallic coating 50A is formed on the first casing part 10a, the compressor 5A less likely to corrode can be manufactured.
The internal space 70 of the casing is divided into the first space 71 and the second space 72 by the upper bearing holding member 61 or other parts. However, the upper bearing holding member 61 or the other parts do not hermetically isolate the first space 71 and the second space 72 from each other; thus, the first space 71 and the second space 72 are communicated with each other. The volume of the second space 72 is greater than that of the first space 71. The motor 20 is disposed in the second space 72.
The low-pressure gas refrigerant to be suctioned from the suction pipe 15 proceeds directly into the compression chamber 43 without being released into the internal space 70 of the casing 10. The high-pressure gas refrigerant to be discharged from the discharge port 45 of the compression mechanism 40 is released into the first space 71. Since the first space 71 is communicated with the second space 72, the first space 71 and the second space 72 are each a high-pressure space configured to be filled with the high-pressure gas refrigerant.
(2-1)
Substantially the entire region of the casing 10 covers the high-pressure space. Unlike the low-pressure fluid, the high-pressure fluid contained in the high-pressure space has a high temperature. For this reason, the outer surface of the casing 10 is less likely to freeze. Moreover, the metallic coating 50A or the resin coating 50B protects the casing from moisture attached to the outer surface of the casing 10. As a result, the occurrence of corrosion of the outer surface of the casing 10 is reduced.
(2-2)
The low-temperature, low-pressure gas refrigerant to be suctioned into the compressor 5A flows directly into the compression chamber 43 without drifting in the internal space 70 of the casing 10. Therefore, since the portions in the casing 10 with which the low-temperature, low-pressure gas refrigerant comes into contact are extremely limited, freezing of the outer surface of the casing 10 can be reduced effectively.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-150616 | Jul 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/027118 | 7/26/2017 | WO | 00 |
