WO2023176596A1

WO2023176596A1 - Refrigerant compressor

Info

Publication number: WO2023176596A1
Application number: PCT/JP2023/008623
Authority: WO
Inventors: 隆太田中; 雅祐中島; 紘樹小林; 陽介赤松; 誠一郎吉永
Original assignee: 株式会社Ihi
Priority date: 2022-03-14
Filing date: 2023-03-07
Publication date: 2023-09-21

Abstract

A refrigerant compressor according to the present invention compresses a refrigerant circulating in a refrigerant circulation system. The refrigerant compressor comprises: a rotary body having a shaft and a protruding portion which radially protrudes from the shaft and rotates together with the shaft; a non-contact-type bearing unit that rotatably supports the rotary body; a housing having an internal space in which the protruding portion is received; a suction port which opens to the internal space and through which the refrigerant is supplied into the internal space; a refrigerant flow path which communicates with the suction port and which is connected to an evaporator; an ejection port through which the refrigerant is discharged from the internal space; and a recirculation path that causes the internal space and the evaporator to communicate with each other through a recirculation port provided in the internal space. The recirculation port is positioned vertically lower than the protruding portion.

Description

refrigerant compressor

The present disclosure relates to a refrigerant compressor.

Patent Document 1 and Patent Document 2 disclose technologies related to heat pumps. A heat pump has, for example, a refrigerant circulation system in which a refrigerant compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in a ring. In a refrigerant circulation system, refrigerant vaporized by an evaporator is compressed in a refrigerant compressor, and then liquefied by dissipating heat in a condenser. The liquefied refrigerant is supplied to the evaporator via the expansion valve and is vaporized in the evaporator. The vaporized refrigerant is again supplied to the refrigerant compressor. In a refrigerant compressor, a shaft is rotatably supported by a pair of bearings provided inside a housing. The rotation of the impeller together with the shaft compresses the refrigerant.

Japanese Patent Application Publication No. 2010-071082 JP 2019-090602 Publication

Non-contact bearings such as air bearings, gas bearings, or magnetic bearings are attracting attention as a technology for supporting the rotating body in the refrigerant circulation system as described above. Such non-contact type bearings have advantages such as less energy loss due to contact friction than contact type bearings such as rolling bearings. On the other hand, in non-contact type bearings, displacement of the rotating body is likely to occur when external force is applied. Therefore, care must be taken to prevent contact between the rotating body and the bearing.

The present disclosure describes a refrigerant compressor that suppresses uneven contact between a rotating body and a non-contact bearing during startup.

A refrigerant compressor according to one embodiment of the present disclosure compresses refrigerant circulating in a refrigerant circulation system. The refrigerant compressor includes a shaft, a rotating body having a protrusion that protrudes radially from the shaft and rotates together with the shaft, a non-contact type bearing unit that rotatably supports the rotary body, and an interior that accommodates the protrusion. A housing having a space, a suction port opening into the internal space and supplying refrigerant to the internal space, a refrigerant passage communicating with the suction port and connected to an evaporator, and a discharge hole discharging the refrigerant from the internal space. , a reflux path that communicates the internal space with the evaporator via a reflux port provided in the internal space. The reflux port is located vertically below the protrusion.

According to some aspects of the present disclosure, a refrigerant compressor is provided that suppresses uneven contact between a rotating body and a non-contact bearing during startup.

FIG. 1 is a block diagram showing the configuration of a refrigerator including a refrigerant compressor according to an embodiment. FIG. 2 is a sectional view showing the configuration of the refrigerant compressor of FIG. 1. FIG. 3 is a cross section of the refrigerant compressor taken along line III-III in FIG. FIG. 4(a) is a simplified cross-sectional view of the refrigerant compressor during operation. FIG. 4(b) is a simplified cross-sectional view of the refrigerant compressor during suspension of operation. FIG. 5 is a diagram showing a connection configuration between a refrigerant compressor and an evaporator. FIG. 6(a) is a cross-sectional view showing a refrigerant compressor of a comparative example during suspension of operation. FIG. 6(b) is a sectional view showing the refrigerant compressor of the comparative example during operation. FIG. 7 is a sectional view showing a refrigerant compressor of Modification 1. FIG. 8 is a sectional view showing a refrigerant compressor according to modification 2.

In the above refrigerant compressor, the refrigerant vaporized in the evaporator is supplied to the internal space of the housing from the suction port through the refrigerant flow path, and is discharged to the outside from the discharge hole. The refrigerant compressor described above includes a reflux path that communicates the internal space with the evaporator via a reflux port provided in the internal space of the housing. The reflux port is located vertically below the protrusion of the rotating body. Therefore, the refrigerant liquefied in the internal space of the housing flows from the internal space of the housing to the outside through the return path before reaching the protrusion. Here, the liquid that has flowed through the reflux path is refluxed to the evaporator. The evaporator vaporizes the liquid and supplies it again as refrigerant to the refrigerant compressor. With this configuration in which the liquid in the internal space is returned to the evaporator and vaporized, the liquid can be efficiently removed from the internal space. As a result, it is possible to prevent the liquid level in the internal space from reaching the protrusion, and it is possible to prevent the shaft from becoming unbalanced in rotation. Thereby, uneven contact between the rotating body and the bearing unit at the time of starting can be suppressed.

In some embodiments, the return flow path may be constituted by the refrigerant flow path itself. In this case, the refrigerant flow path has both the function of supplying vaporized refrigerant from the evaporator and the function of returning liquefied refrigerant in the internal space of the housing to the evaporator. According to this configuration, the function of returning liquefied refrigerant to the evaporator and the function of supplying refrigerant from the evaporator can be provided in the same flow path, so the configuration of the refrigerant compressor can be simplified. .

In some embodiments, the bearing unit may include a pair of bearings that are arranged side by side in the axial direction in which the shaft extends and support the shaft in the radial direction. The interior space may have a first interior region, a second interior region, and a third interior region that communicate with each other in the axial direction. The second internal region may be located between the pair of bearings in the axial direction. The first internal region may be located on one side of the pair of bearings in the axial direction. The third internal region may be located on the other side of the pair of bearings in the axial direction. The inlet may communicate with the third interior region. The discharge hole may communicate with the first internal region. In this case, since the refrigerant supplied from the suction port passes through the pair of bearings and is discharged from the discharge hole, the flow of this refrigerant can be used to cool the pair of bearings.

In some embodiments, the return flow path may penetrate the housing vertically downward from the internal space. In this case, the liquid generated in the internal space of the housing easily flows into the reflux path according to gravity. This allows liquid to be effectively removed from the internal space.

In some embodiments, the discharge hole may penetrate the housing vertically downward from the internal space at a position different from the reflux path. In this case, in addition to the reflux path, the discharge hole can also be used as a flow path for removing liquid from the internal space of the housing. Thereby, liquid can be more effectively removed from the internal space.

In some embodiments, the inner wall surface of the housing may include an inclined part between the discharge hole and the reflux path that descends toward the reflux port. In this case, the liquid generated in the internal space of the housing flows more easily into the reflux path than into the discharge hole according to gravity. This makes it possible to actively flow the liquid into the evaporator. When liquid is actively flowed into an evaporator that vaporizes liquid in this way, the flowed liquid is pushed back into the refrigerant compressor, compared to when the liquid is flowed through other equipment such as a condenser where liquid tends to accumulate. Such a situation is unlikely to occur. Therefore, by actively flowing liquid into the evaporator, liquid can be more effectively removed from the internal space.

In some embodiments, the discharge hole may penetrate the housing vertically upward from the internal space. In this case, it is possible to suppress the liquid generated in the internal space of the housing from flowing into the discharge hole, making it more difficult for the liquid to be pushed back into the refrigerant compressor. Thereby, liquid can be more effectively removed from the internal space.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and duplicate descriptions will be omitted as appropriate.

The refrigerator 1 shown in FIG. 1 can be installed in a building or factory, for example, to generate cooling water for air conditioning. The refrigerator 1 includes, for example, a refrigerant compressor 2, a condenser 3, an expansion valve 4, and an evaporator 5. The refrigerant compressor 2, condenser 3, expansion valve 4, and evaporator 5 constitute a refrigerant circulation system 6 in which refrigerant (eg, fluorocarbon) circulates. In the refrigerant circulation system 6, thermal energy is exchanged by circulating the refrigerant through the refrigerant compressor 2, condenser 3, expansion valve 4, and evaporator 5 while changing its phase.

The refrigerant compressor 2 is connected to the condenser 3 via a flow path F1. Condenser 3 is connected to expansion valve 4 via flow path F2. Expansion valve 4 is connected to evaporator 5 via flow path F3. Evaporator 5 is connected to refrigerant compressor 2 via flow path F4. These flow paths F1, F2, F3, and F4 constitute a circulation flow path through which the refrigerant circulates through the refrigerant compressor 2, condenser 3, expansion valve 4, and evaporator 5.

The refrigerant compressor 2 generates compressed refrigerant gas R1 by compressing refrigerant gas R3 supplied from the evaporator 5. The refrigerant compressor 2 supplies the generated compressed refrigerant gas R1 to the condenser 3 via the flow path F1. The condenser 3 generates liquid refrigerant R2 by cooling and liquefying the compressed refrigerant gas R1, which has been compressed by the refrigerant compressor 2 and has become high temperature and high pressure. The condenser 3 supplies the generated liquid refrigerant R2 to the expansion valve 4 via the flow path F2. The expansion valve 4 reduces the pressure of the liquid refrigerant R2 liquefied by the condenser 3. The expansion valve 4 supplies the reduced pressure liquid refrigerant R2 to the evaporator 5 via the flow path F3.

The evaporator 5 generates refrigerant gas R3 by evaporating the liquid refrigerant R2 whose pressure has been reduced by the expansion valve 4. The evaporator 5 cools an object to be cooled (for example, cooling water) using the heat of vaporization when refrigerant gas R3 is generated by evaporating the liquid refrigerant R2. The evaporator 5 supplies the generated refrigerant gas R3 to the refrigerant compressor 2 via the flow path F4. The refrigerant gas R3 supplied to the refrigerant compressor 2 is compressed in the refrigerant compressor 2, and then supplied to the condenser 3 again as compressed refrigerant gas R1. Compressed refrigerant gas R1, liquid refrigerant R2, and refrigerant gas R3 are examples of states that the refrigerant can take in the refrigerant circulation system 6.

Next, the configuration of the refrigerant compressor 2 will be described in detail with reference to FIG. 2. The refrigerant compressor 2 is a so-called two-stage compressor. As shown in FIG. 2, the refrigerant compressor 2 includes a shaft 10, a compressor unit 30, and a motor unit 50. In the following description, "upper D1A" means the upper part in the vertical direction (direction of gravity) when the refrigerant compressor 2 is installed at the location where it is used, and "lower D1B" means the lower part in the vertical direction. do. In this embodiment, the refrigerant compressor 2 is arranged so that the rotation axis L of the shaft 10 extends in the horizontal direction when it is installed at the location where it is used. Therefore, the axial direction D2 in which the rotational axis L extends is perpendicular to the vertical direction. In the following description, "upstream side" means the upstream side in the flow direction of the refrigerant flowing through the refrigerant compressor 2, and "downstream side" means the downstream side in the flow direction.

The compressor unit 30 includes a first impeller 31 , a second impeller 32 , a first impeller housing 41 that accommodates the first impeller 31 , and a second impeller housing 42 that accommodates the second impeller 32 . The first impeller 31 and the first impeller housing 41 constitute a compression stage on the low pressure side. The second impeller 32 and the second impeller housing 42 constitute a compression stage on the high pressure side. The first impeller 31 and the second impeller 32 are attached to one end 10a of the shaft 10. Each of the first impeller 31 and the second impeller 32 is a protrusion that protrudes outward in the radial direction from the shaft 10, and rotates around the rotation axis L together with the shaft 10. The first impeller 31 and the second impeller 32 are arranged, for example, so that their back surfaces face each other with a gap in between in the axial direction D2. The second impeller 32 is, for example, arranged coaxially with the first impeller 31 and has the same dimensions as the first impeller 31. The first impeller 31 is located, for example, between the second impeller 32 and the motor unit 50 in the axial direction D2. Hereinafter, when the first impeller 31 and the second impeller 32 are to be described without particular distinction, they will be collectively referred to as the "impeller 35."

The first impeller housing 41 and the second impeller housing 42 are connected to each other in the axial direction D2. An interstage plate 43 is provided between the first impeller housing 41 and the second impeller housing 42 . The interstage plate 43 is connected to the first impeller housing 41 and the second impeller housing 42 in the axial direction D2. Therefore, the second impeller housing 42 is connected to the first impeller housing 41 via the interstage plate 43 in the axial direction D2.

The motor unit 50 includes a motor 51 and a motor housing 55 that accommodates the motor 51. The motor 51 is a drive source for driving the compressor unit 30. Motor 51 includes a stator 52 fixed to motor housing 55 and a rotor 53 fixed to shaft 10. The rotor 53 faces the stator 52 with a gap therebetween. The motor housing 55 is connected to the first impeller housing 41 in the axial direction D2. The motor housing 55 , the first impeller housing 41 , the interstage plate 43 , and the second impeller housing 42 constitute the housing 11 of the refrigerant compressor 2 .

The shaft 10 to which the first impeller 31 and the second impeller 32 are attached is accommodated in the internal space S of the housing 11. The internal space S is a space defined by the inner wall surface 11a of the housing 11. In the internal space S, the shaft 10 extends in the axial direction D2 across the motor housing 55, the first impeller housing 41, the interstage plate 43, and the second impeller housing 42. The shaft 10 is rotatably supported around the rotation axis L by a pair of

bearings

60, 60 and a pair of

bearings

64, 64 provided inside the motor housing 55. The pair of

bearings

60, 60 and the pair of

bearings

64, 64 constitute a "bearing unit" of the present disclosure. The pair of

bearings

60, 60 are provided so as to surround the shaft 10, and are arranged side by side at positions sandwiching the motor 51 in the axial direction D2.

The internal space S of the housing 11 has a first internal area S1, a second internal area S2, and a third internal area S3. The first internal region S1, the second internal region S2, and the third internal region S3 are arranged in order in the axial direction D2 and communicate with each other. The second internal region S2 is located between the pair of

bearings

60, 60 in the axial direction D2. The second internal region S2 is surrounded by the central portion of the motor housing 55. A motor 51 sandwiched between a pair of

bearings

60, 60 is arranged in the second internal region S2. The first internal region S1 is located on one side where the first impeller 31 and the second impeller 32 are located with the pair of

bearings

60, 60 in between in the axial direction D2. The first internal region S1 is mainly surrounded by the first impeller housing 41, the second impeller housing 42, and the interstage plate 43. The third internal region S3 is located on the other side with the pair of

bearings

60, 60 interposed therebetween in the axial direction D2. The third internal region S3 is surrounded by the end of the motor housing 55 located on the opposite side of the first impeller housing 41 in the axial direction D2.

The housing 11 has a suction hole 12 and a discharge hole 13. The suction hole 12 is a hole for sucking the refrigerant gas R3 from the evaporator 5 (see FIG. 1) into the internal space S. The suction hole 12 communicates with the internal space S and is also connected to the evaporator 5 via a flow path F4. The refrigerant gas R3 sucked into the internal space S is compressed by the first impeller 31 and the second impeller 32 that rotate together with the shaft 10. The discharge hole 13 is a hole for discharging the compressed refrigerant gas R1 compressed in the internal space S from the internal space S to the condenser 3 (see FIG. 1). The discharge hole 13 communicates with the internal space S and is also connected to the condenser 3 via the flow path F1. The suction hole 12 is formed in the motor housing 55, for example, and communicates with the third internal region S3. The discharge hole 13 is formed in the second impeller housing 42, for example, and communicates with the first internal region S1. More specific configurations of the suction hole 12 and the discharge hole 13 will be described later.

The motor housing 55 has, for example, a cylindrical side wall 56 centered on the rotation axis L, and a disc-shaped end wall 57 that closes one end of the side wall 56 in the axial direction D2. Side wall 56 surrounds rotor 53 fixed to shaft 10 . A stator 52 is fixed to the inner surface 56a of the side wall 56. A pair of

support parts

61, 61 that support a pair of

bearings

60, 60 are provided on the inner surface 56a of the side wall 56.

As shown in FIG. 3, each of the pair of

support parts

61, 61 includes a ring-shaped member 62 and four rod-shaped members 63. The ring-shaped member 62 has, for example, an annular shape when viewed from the axial direction D2. The ring-shaped member 62 is arranged to surround the bearing 60 in the circumferential direction D3, and is fixed to the inner surface 56a of the side wall 56. The four rod-shaped members 63 extend in a cross shape with the bearing 60 at the center, and connect the bearing 60 and the ring-shaped member 62. The shaft 10 is arranged to pass through the inside of the bearing 60. The bearing 60 is a non-contact radial bearing. Examples of the bearing 60 include, for example, an air bearing, a gas bearing, or a magnetic bearing. When the shaft 10 rotates, the bearing 60 is arranged with a gap between the rotor 53 (see FIG. 2) and supports the rotor 53 and the shaft 10 in a non-contact manner in the radial direction.

Refer to FIG. 2 again. The second internal region S2 communicates with the first internal region S1 through the space between each rod-shaped member 63 in the circumferential direction D3 (see FIG. 3) and the gap between the rotor 53 and one bearing 60. ing. The second internal region S2 communicates with the third internal region S3 via the space between each rod-shaped member 63 in the circumferential direction D3 and the gap between the rotor 53 and the other bearing 60. Therefore, in the internal space S of the housing 11, fluid such as the refrigerant gas R3 can move through the first internal area S1, the second internal area S2, and the third internal area S3.

The pair of

bearings

64, 64 are provided, for example, in the third internal region S3 so as to surround the shaft 10, and are arranged side by side with an interval in the axial direction D2. The pair of

bearings

64, 64 are non-contact type thrust bearings. Examples of the pair of

bearings

64, 64 include, for example, air bearings, gas bearings, or magnetic bearings. A thrust collar 65 is provided between the pair of

bearings

64, 64. The thrust collar 65 is a protruding part that protrudes from the shaft 10 in a brim shape, and rotates around the rotation axis L together with the shaft 10. An annular spacer 67 surrounding the outer periphery of the thrust collar 65 is provided between the pair of

bearings

64 , 64 .

The pair of

bearings

64, 64 and the spacer 67 are fastened together by a plurality of fastening bolts. A pair of

bearings

64, 64 and a spacer 67, which are integral with each other, are fixed to the inner surface 56a of the side wall 56. The pair of

bearings

64, 64 and the spacer 67 define an accommodation space in which the thrust collar 65 is accommodated. In this accommodation space, the thrust collar 65 rotates around the rotation axis L together with the shaft 10 without contacting the pair of bearings 64 and the spacer 67. The pair of

bearings

64, 64, the spacer 67, and the thrust collar 65 support the rotor 53 and the shaft 10 in the axial direction D1 in a non-contact manner. The thrust collar 65, the impeller 35, and the shaft 10 constitute a rotating body RB that rotates integrally with each other.

The first impeller housing 41 is arranged so as to close the opening of the side wall 56 on the side opposite to the end wall 57 in the axial direction D2. The first impeller housing 41 includes an inlet 41a, a diffuser passage 41b, a scroll passage 41c, and an outlet 41d. The inlet 41 a is an opening coaxial with the shaft 10 and communicates with the inside of the motor housing 55 . Therefore, the refrigerant gas R3 sucked into the motor housing 55 flows into the inlet 41a. The first impeller 31 is arranged on the back side of the inlet 41a. The rotation of the first impeller 31 imparts velocity energy to the refrigerant gas R3.

The scroll passage 41c is formed to surround the first impeller 31. The diffuser passage 41b is formed between the first impeller 31 and the scroll passage 41c. The diffuser flow path 41b compresses the refrigerant gas R3 by converting velocity energy imparted to the refrigerant gas R3 into compression energy. The scroll passage 41c discharges the refrigerant gas R3 compressed by the diffuser passage 41b to the outside of the first impeller housing 41 from the outlet 41d. The outflow port 41d is, for example, an opening that opens on the outer peripheral surface of the first impeller housing 41.

The second impeller housing 42 includes an inlet 42 a, a diffuser passage 42 b, a scroll passage 42 c, and a discharge hole 13 . The inlet 42a is an opening coaxial with the inlet 41a of the first impeller housing 41, and faces opposite to the inlet 41a. The inlet 42a is connected to the outlet 41d of the first impeller housing 41 via an external pipe 70. Therefore, the refrigerant gas R3 from the outlet 41d flows into the inlet 42a via the external pipe 70. The second impeller 32 is arranged on the back side of the inlet 42a. The rotation of the second impeller 32 imparts velocity energy to the refrigerant gas R3.

The scroll passage 42c is formed to surround the second impeller 32. The diffuser passage 42b is formed between the second impeller 32 and the scroll passage 42c. The diffuser flow path 42b further compresses the refrigerant gas R3 by converting the velocity energy imparted to the refrigerant gas R3 into compression energy. As a result, compressed refrigerant gas R1 is generated. The scroll passage 42c discharges the generated compressed refrigerant gas R1 from the discharge hole 13 to the outside of the second impeller housing 42.

The configuration of the above-mentioned suction hole 12 and discharge hole 13 will be explained in more detail. The suction hole 12 includes a suction port 12a that opens to the inner wall surface 11a. The suction port 12a is located vertically lower D1B than the protrusion of the rotating body RB. The fact that the suction port 12a is located below the protrusion D1B of the rotating body RB means that the suction port 12a is located below the bottom D1B of the protrusion when the refrigerant compressor 2 is installed at the installation location. means located. The "projection" here may be one of the impeller 35 and the thrust collar 65 that is located lower. For example, when the “protrusion” refers to the impeller 35 (that is, when the impeller 35 is located below the thrust collar 65), the lower end of the “protrusion” refers to the lower end 35a of the impeller 35. In this case, the suction port 12a should just be located below the lower end 35a of the impeller 35 D1B. In other words, the suction port 12a only needs to be located in the region RH between the outer surface 56b located at the lower end of the housing 11 and the lower end 35a of the impeller 35. The lower end 35a of the impeller 35 is a portion of the impeller 35 located at the lowest position D1B. The lower end 35a of the impeller 35 can also be said to be the tip of the impeller 35 located at the lowest end, that is, the tip of the impeller 35 closest to the lower end of the housing 11.

For the suction port 12a to be located below the impeller 35 in D1B, at least a portion of the suction port 12a may be located below the lower end 35a of the impeller 35 in the D1B. That is, it is sufficient that the suction port 12a has at least a portion located in the region RH. Therefore, the suction port 12a may have a portion that overlaps the impeller 35 in the horizontal direction. In this embodiment, the first impeller 31 and the second impeller 32 are arranged at the same height and have the same dimensions. Therefore, the height of the lower end of the first impeller 31 and the height of the lower end of the second impeller 32 are the same. If the lower end of the first impeller 31 and the lower end of the second impeller 32 are different from each other, the lower end 35a of the impeller 35 may be the lower end of the first impeller 31 or the second impeller 32, which has a larger outer diameter. .

On the other hand, when the "protrusion" refers to the thrust collar 65 (that is, when the thrust collar 65 is located below the impeller 35), the lower end of the "protrusion" refers to the lower end 65a of the thrust collar 65. In this case, the suction port 12a only needs to be located below the lower end 65a of the thrust collar 65 D1B. The lower end 65a of the thrust collar 65 is a portion of the thrust collar 65 located at the lowest position D1B. The lower end 65a of the thrust collar 65 can also be said to be the tip of the thrust collar 65 located at the lowest end, that is, the tip of the thrust collar 65 closest to the lower end of the housing 11. The fact that the suction port 12a is located below the thrust collar 65 means that at least a portion of the suction port 12a is located below the lower end 65a of the thrust collar 65 D1B. Which of the impeller 35 and the thrust collar 65 is located in the lower direction D1B is appropriately determined according to design requirements.

The suction hole 12 is formed, for example, to penetrate the side wall 56 from the third internal region S3 of the motor housing 55 downward D1B. Specifically, the suction hole 12 vertically penetrates the lower end 56c of the side wall 56 surrounding the third internal region S3 from the inner surface 56a to the outer surface 56b. The lower end portion 56c is a wall portion of the side wall 56 located below D1B in the cross section shown in FIG. Therefore, the suction port 12a opens to the inner surface 56a of the lower end portion 56c and communicates with the third internal region S3. The discharge hole 13 is formed, for example, so as to penetrate the second impeller housing 42 from the first internal region S1 of the second impeller housing 42 downward D1B. That is, the discharge hole 13 vertically penetrates the lower end portion 42d of the second impeller housing 42 surrounding the first internal region S1. The lower end portion 42d is a wall portion located below D1B of the second impeller housing 42 in the cross section shown in FIG. The discharge hole 13 communicates with the first internal region S1. The discharge port 13a of the discharge hole 13 is open to the outer surface 42e of the lower end portion 42d.

The inner surface 56a of the side wall 56 has an inclined portion P1 between the suction hole 12 and the discharge hole 13 in the axial direction D2. The inclined portion P1 may be a tapered surface whose diameter decreases as it approaches the discharge hole 13 from the suction hole 12. In the cross section shown in FIG. 2, the inclined portion P1 is inclined downward toward the suction port 12a. That is, the inclined portion P1 is inclined so as to be located downward D1B as it approaches the suction port 12a from the discharge hole 13. The inclined portion P1 is formed continuously, for example, from the end of the side wall 56 on the first impeller housing 41 side to the suction port 12a.

The flow of refrigerant flowing through the refrigerant compressor 2 having the above configuration will be explained. Here, for simplicity, explanation will be given using a simplified model of the refrigerant compressor 2 as shown in FIGS. 4(a) and 4(b). 4(a) and 4(b), the first impeller 31 and the second impeller 32 are collectively shown as one impeller 35, and the first impeller housing 41, the interstage plate 43, and the second impeller housing 42 are shown as one impeller 35. They are collectively shown as one impeller housing 45. In addition, in the following simplified model, the pair of

bearings

64, 64, the thrust collar 65, and the spacer 67 are omitted for simplicity, and the "protrusion" in the present disclosure is considered to be the "impeller 35" for explanation. do. Note that when the "protrusion" in the present disclosure is interpreted as referring to the "thrust collar 65", the "impeller 35" can be replaced with the "thrust collar 65" for explanation.

As shown in FIG. 4(a), when the refrigerant compressor 2 is in operation, the refrigerant gas R3 supplied to the refrigerant compressor 2 from the upstream evaporator 5 (see FIG. It is sucked (supplied) into the third internal region S3 from the suction hole 12 formed in the . The refrigerant gas R3 sucked into the third internal region S3 sequentially passes through the second internal region S2 and the first internal region S1. At this time, the refrigerant gas R3 cools the pair of

bearings

60, 60, the rotor 53, and the stator 52 on the circulation path. The refrigerant gas R3 that has reached the impeller 35 in the first internal region S1 is compressed by the rotation of the impeller 35. Thereby, compressed refrigerant gas R1 is generated. The generated compressed refrigerant gas R1 is discharged from the discharge hole 13 formed in the lower part D1B of the impeller housing 45 to the condenser 3 on the downstream side.

As shown in FIG. 4(b), when the refrigerant compressor 2 is out of operation, the refrigerant gas R3 filling the internal space S of the housing 11 liquefies as the temperature decreases and becomes a liquid R4. This may occur in space S. The liquid R4 may be a liquid containing a liquid refrigerant R2 obtained by liquefying the refrigerant gas R3. In this embodiment, since the suction hole 12 is formed in the lower part D1B of the motor housing 55, the liquid R4 in the internal space S flows out of the housing 11 from the suction hole 12 according to gravity. The suction hole 12 is connected to the evaporator 5 (see FIG. 1) on the upstream side. Therefore, the liquid R4 flowing out from the suction hole 12 is returned to the evaporator 5. The liquid R4 returned to the evaporator 5 is vaporized in the evaporator 5, and is again supplied to the internal space S from the suction hole 12 as a refrigerant gas R3.

Therefore, in this embodiment, the suction hole 12 not only functions as a suction hole for sucking the refrigerant gas R3 from the upstream evaporator 5 into the internal space S of the housing 11, but also functions as a suction hole for sucking the refrigerant gas R3 from the upstream evaporator 5 into the internal space S. It has a function as a reflux hole that refluxes the water to the evaporator 5 on the upstream side. Therefore, the suction port 12a of the suction hole 12 also functions as a reflux port through which the liquid R4 that is refluxed to the evaporator 5 on the upstream side flows. That is, in this embodiment, the suction hole 12 is also an inflow path for the refrigerant gas R3 that flows from the upstream evaporator 5 into the internal space S of the housing 11, and flows out from the internal space S to the upstream evaporator 5. It is also an outflow path for liquid R4. It can also be said that the reflux hole for refluxing the liquid R4 generated in the internal space S to the evaporator 5 is configured by the suction hole 12 itself (that is, configured integrally with the suction hole 12). In other words, it can be said that the suction port 12a itself constitutes a reflux port. The suction port 12a is connected to the evaporator 5 via the suction hole 12 and the flow path F4 (see FIG. 1). The suction hole 12 and the flow path F4 constitute a refrigerant flow path that supplies the refrigerant gas R3 from the evaporator 5 to the internal space S. It can be said that the suction hole 12 and the flow path F4 constitute a reflux path for refluxing the liquid R4 generated in the internal space S to the evaporator 5.

Furthermore, in this embodiment, the discharge hole 13 is formed in the lower part D1B of the impeller housing 45. Therefore, as shown in FIG. 4(b), the liquid R4 generated in the first internal region S1 flows out from the discharge hole 13 according to gravity. The liquid R4 discharged (discharged) from the discharge hole 13 flows to the condenser 3 on the downstream side (see FIG. 1) and circulates through the refrigerant circulation system 6. Therefore, in this embodiment, the liquid R4 generated in the internal space S is expelled from the internal space S to the outside through the suction hole 12 and the discharge hole 13 formed in the lower part D1B of the housing 11.

FIG. 5 shows a connection configuration between the suction port 12a of the refrigerant compressor 2 and the evaporator 5. As shown in FIG. 5, the evaporator 5 is located below the suction port 12a of the refrigerant compressor 2 D1B. The evaporator 5 is connected to the suction port 12a via the flow path F4 and the suction hole 12. It can be said that the flow path F4 and the suction hole 12 communicate the internal space S of the refrigerant compressor 2 (see FIG. 2) with the evaporator 5 via the suction port 12a. The flow path F4 has a straight flow path portion FP1 and a straight flow path portion FP2. The straight flow path portion FP1 extends downward D1B from the suction port 12a. The straight flow path portion FP2 extends in the axial direction D2 from the lower end of the straight flow path portion FP1, and is connected to the downstream flow port 5a of the evaporator 5.

The liquid R4 from the suction port 12a flows downward D1B through the straight flow path portion FP1 according to gravity, and then flows through the straight flow path portion FP2 in the axial direction D1 to flow into the flow port 5a of the evaporator 5. According to this configuration, the liquid R4 generated in the refrigerant compressor 2 can be easily returned to the evaporator 5 using gravity. The connection configuration between the refrigerant compressor 2 and the evaporator 5 is not limited to the example shown in FIG. 5. For example, the flow path F4 may be connected to the communication port 5a on the downstream side of the evaporator 5, and another flow path may be connected to the communication port 5b on the upstream side of the evaporator 5. The communication port 5b may be connected to the suction port 12a or a hole different from the suction port 12a via this other flow path. In this case, the liquid R4 can be returned to the evaporator 5 via the other flow path. A curved portion that curves downward D1B may be formed in part or all of the straight flow path portion FP2 of the flow path F4. In this case, the refrigerant compressor 2 may include a mechanism for evaporating a pool of liquid R4 that may occur in the curved portion.

The effects of the refrigerant compressor 2 and refrigerator 1 according to the present embodiment described above will be explained together with the problems that the comparative example has. FIGS. 6A and 6B show a simplified refrigerant compressor 200 according to a comparative example. In the refrigerant compressor 200, the suction hole 112 formed in the motor housing 155 of the housing 111 is located above the impeller 135 attached to the shaft 100 D1A. The discharge hole 113 formed in the impeller housing 145 is located above the impeller 135 D1A. In the refrigerant compressor 200, the refrigerant gas R3 sucked into the internal space S100 from the suction hole 112 passes through the pair of

bearings

160, 160, etc., and reaches the impeller 135. Refrigerant gas R3 is compressed by the rotation of impeller 135, and is discharged from discharge hole 113 of impeller housing 145 as compressed refrigerant gas R1.

The inventor of the present disclosure has proposed that, as shown in FIG. 6(a), when the refrigerant compressor 200 is out of operation, the refrigerant gas R3 filling the internal space S100 liquefies and remains in the internal space S100 as a liquid R4. However, as a result, it was discovered that the water level of liquid R4 sometimes reaches the impeller 135 in the internal space S100. The inventor of the present disclosure has discovered that since the lower portion of the impeller 135 is immersed in the liquid R4, when the refrigerant compressor 200 is operated in this state, it rotates while receiving a large resistance force from the liquid R4, and It has been noticed that rotating while receiving a large resistance force from the liquid R4 may cause uneven contact between the rotating body and the non-contact type bearing.

On the other hand, since the upper part of the impeller 135 is not immersed in the liquid R4, it rotates without being subjected to the large resistance force that acts on the lower part of the impeller 135.

As a result, as shown in FIG. 6(b), the rotational balance of the shaft 100 is disrupted, causing the shaft 100 to tilt, and an excessive load may be applied to the

bearings

160, 160 that support the shaft 100. If such a load acts on the

non-contact type bearings

160, 160, the

bearings

160, 160 may not be able to withstand the load, and there is a possibility that the

bearings

160, 160 may not be able to exhibit the desired performance due to damage or the like. As a result, problems such as a decrease in compression performance may occur. If a high-strength bearing or a large-sized bearing is used as a bearing that can withstand the above-mentioned excessive load, there is a risk that the refrigerant compressor 200 will become more expensive and larger.

On the other hand, in this embodiment, the suction port 12a is located below the impeller 35 in the vertical direction D1B. Therefore, as shown in FIG. 4(b), the liquid R4 generated in the internal space S flows from the internal space S to the outside through the suction hole 12 before reaching the impeller 35. The liquid R4 that has flowed through the suction hole 12 is returned to the evaporator 5 on the upstream side via the flow path F4. The evaporator 5 vaporizes the liquid R4 and supplies it as a refrigerant gas R3 to the refrigerant compressor 2 via the flow path F4 and the suction hole 12. With this configuration in which the liquid R4 in the internal space S is returned to the evaporator 5 and vaporized, the liquid R4 can be efficiently removed from the internal space S. As a result, it is possible to prevent the level of the liquid R4 in the internal space S from reaching the impeller 35, and it is possible to prevent the rotational balance of the shaft 10 from becoming unbalanced. Thereby, it is possible to suppress unevenness in the contact state between the rotating body RB and the bearing unit (the pair of

bearings

60, 60 and the pair of bearings 64, 64) at the time of starting (at the time of starting rotation). As a result, it is possible to suppress a situation in which an excessive load is applied to the bearing unit, and it is possible to suppress a situation in which a problem such as a decrease in compression performance due to a decrease in the performance of the bearing unit occurs.

In this embodiment, the suction hole 12 and the flow path F4 also function as a reflux path for refluxing the liquid R4 in the internal space S to the evaporator 5. In other words, the suction hole 12 and the flow path F4 have both the function of sucking the refrigerant gas R3 from the evaporator 5 and the function of circulating the liquid R4 in the internal space S to the evaporator 5. According to this configuration, the function of refluxing the liquid R4 to the evaporator 5 and the function of supplying the refrigerant gas R3 from the evaporator 5 can be provided in the same flow path. In this embodiment, since a separate reflux path for refluxing the liquid R4 to the evaporator 5 is not provided, the configuration of the refrigerant compressor 2 is further simplified.

In this embodiment, the suction port 12a communicates with the third internal region S3, and the discharge hole 13 communicates with the first internal region S1. In this configuration, the refrigerant gas R3 sucked from the suction port 12a passes through the pair of

bearings

60, 60 and the motor 51 and is discharged from the discharge hole 13. 60 and motor 51 can be cooled. According to this configuration, a configuration that does not separately provide a mechanism for cooling the pair of

bearings

60, 60 and the motor 51 can be adopted. Alternatively, a simplified mechanism for cooling the

bearings

60, 60 and the motor 51 can be used, so the configuration of the refrigerant compressor 2 can be simplified. In reality, as shown in FIG. 2, the refrigerant gas R3 also passes through the pair of

bearings

64, 64, so in addition to cooling the pair of

bearings

60, 60 and the motor 51, it also cools the pair of

bearings

64, 64. You can also do this.

In this embodiment, the suction hole 12 penetrates the side wall 56 from the third internal region S3 downward D1B. With this configuration, the liquid R4 generated in the internal space S easily flows into the suction port 12a according to gravity. Thereby, the liquid R4 can be effectively removed from the internal space S.

In this embodiment, the discharge hole 13 penetrates the second impeller housing 42 from the first internal region S1 downward D1B. In this configuration, the discharge hole 13 can also be used as a flow path for removing the liquid R4 from the internal space S, so that the liquid R4 can be removed from the internal space S more effectively.

In this embodiment, the inner surface 56a of the side wall 56 includes an inclined portion P1 that descends toward the suction port 12a. With this configuration, the liquid R4 generated in the internal space S flows more easily into the suction hole 12 than into the discharge hole 13 according to gravity. Thereby, it becomes possible to actively flow the liquid R4 to the evaporator 5 on the upstream side rather than the condenser 3 on the downstream side. In this way, when the liquid R4 is actively flowed into the evaporator 5 that vaporizes the liquid R4, compared to the case where the liquid R4 is actively flowed into the condenser 3 where the liquid R4 tends to accumulate, the flowed liquid R4 fills the internal space. A situation where you are pushed back by S is unlikely to occur. If the configuration is such that the liquid R4 is actively flowed into the condenser 3, the liquid R4 tends to accumulate because the condenser 3 is a device that generates the liquid refrigerant R2. If the compressed refrigerant gas R1 flows into the condenser 3 from the discharge hole 13 in this state, a phenomenon may occur in which the liquid R4 accumulated in the condenser 3 is pushed back into the internal space S by the amount of compressed refrigerant gas R1 that has flowed into the condenser 3. be. Therefore, if the liquid R4 is configured to actively flow into the evaporator 5 instead of the condenser 3, it is possible to prevent the liquid R4 from being pushed back into the internal space S. can be eliminated more effectively.

Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the embodiment described above.

<Modification 1>
FIG. 7 shows a simplified refrigerant compressor 2A according to Modification 1. In FIG. In the embodiment described above, an example has been described in which the suction hole 12 also functions as a reflux hole for refluxing the liquid R4 in the internal space S to the evaporator 5. In this modification, a case will be described in which the reflux hole 12B is formed separately from the suction hole 12A. That is, in this modification, the reflux hole 12B is not configured by the suction hole 12A itself, but is configured separately from the suction hole 12A.

The suction hole 12A is formed, for example, in the motor housing 55A so as to communicate with the third internal region S3, and is located above the impeller 35 D1A. The suction hole 12A is connected to the upstream evaporator 5 (see FIG. 1) via a flow path F4. The refrigerant gas R3 sucked into the third internal region S3 from the suction hole 12A passes through the second internal region S2 and the first internal region S1 in order. At this time, the refrigerant gas R3 cools the pair of

bearings

60, 60 and the motor 51 on the circulation path. The refrigerant gas R3 that has reached the impeller 35 in the first internal region S1 is compressed by the rotation of the impeller 35. Thereby, compressed refrigerant gas R1 is generated. The generated compressed refrigerant gas R1 is discharged from the discharge hole 13 formed in the lower part D1B of the impeller housing 45 to the condenser 3 (see FIG. 1) on the downstream side. The flow path F4 and the suction hole 12A constitute a refrigerant flow path that supplies the refrigerant gas R3 from the evaporator 5 to the internal space S.

On the other hand, the reflux hole 12B is formed at the same position as the suction hole 12 of the embodiment described above. That is, the circulation hole 12B is formed so as to penetrate the motor housing 55A from the third internal region S3 of the housing 11A downward D1B. Therefore, the recirculation port 12b of the recirculation hole 12B that opens on the inner surface 56a of the motor housing 55A is located below the lower end 35a of the impeller 35, similar to the suction port 12a according to the embodiment described above. The reflux hole 12B is connected to the upstream evaporator 5 (see FIG. 1) via a flow path different from the flow path F4. This flow path and the reflux hole 12B constitute a reflux path for refluxing the liquid R4 to the evaporator 5.

The liquid R4 generated in the internal space S when the operation is stopped flows into the reflux hole 12B from the reflux port 12b of the lower part D1B, and is refluxed to the evaporator 5 via the reflux hole 12B. The liquid R4 returned to the evaporator 5 is vaporized in the evaporator 5, and is again supplied to the internal space S from the suction hole 12A as a refrigerant gas R3. Even with such a configuration, the liquid R4 generated in the internal space S can be removed from the internal space S through the reflux hole 12B, so that the same effects as in the embodiment described above can be achieved.

<Modification 2>
FIG. 8 shows a simplified refrigerant compressor 2B according to a second modification. In the embodiment described above, an example was described in which the discharge hole 13 is formed in the lower part D1B of the impeller housing 45. In this modification, an example will be described in which the discharge hole 13A is formed above the impeller housing 45A D1A. The discharge hole 13A is formed, for example, so as to penetrate the impeller housing 45A from the first internal region S1 of the housing 11B upward D1A. That is, the discharge hole 13A vertically passes through the upper end portion 42f of the impeller housing 45A surrounding the first internal region S1. The upper end portion 42f may be a wall portion located above D1A of the impeller housing 45A.

Even with this form, the liquid R4 generated in the internal space S can be removed from the internal space S through the suction hole 12, so the same effects as in the embodiment described above can be achieved. Furthermore, in this modification, since it is possible to suppress the liquid R4 generated in the internal space S from flowing into the discharge hole 13A, it becomes more difficult for the liquid R4 to be pushed back into the refrigerant compressor 2. Thereby, the liquid R4 can be more effectively removed from the internal space S.

The present disclosure is not limited to the embodiment and each modification example described above, and various other modifications are possible. For example, the embodiments and modifications described above may be combined with each other depending on the desired purpose and effect. In the embodiment described above, the refrigerant compressor 2 includes two impellers (a first impeller and a second impeller). However, the refrigerant compressor may also include one impeller. The direction of the back surface of the impeller is not particularly limited, and may be changed as appropriate depending on the required specifications.

In the embodiment described above, the suction hole 12 is formed to communicate with the third internal region S3, and the discharge hole 13 is formed so as to communicate with the first internal region S1. However, both the suction hole 12 and the discharge hole 13 may be formed to communicate with the first internal region S1. That is, both the suction hole 12 and the discharge hole 13 may be formed in the impeller housing 45. In this case, a hole through which a cooling medium flows to cool the pair of

bearings

60, 60 and the motor 51 may be formed separately. The suction hole 12 may be formed in the end wall 57 as long as it is located below the impeller 35 D1B.

[Additional note]
The present disclosure includes the following configurations.

The refrigerant compressor of the present disclosure is [1] a refrigerant compressor that compresses refrigerant circulating in a refrigerant circulation system, and includes a shaft and a protrusion that protrudes from the shaft in a radial direction and rotates together with the shaft. a rotating body, a non-contact type bearing unit that rotatably supports the rotating body, a housing having an internal space for accommodating the protrusion, and opening into the internal space to supply the refrigerant to the internal space. The internal air is supplied through an inlet, a refrigerant passage communicating with the inlet and connected to an evaporator, a discharge hole for discharging the refrigerant from the internal space, and a reflux port provided in the internal space. a refrigerant compressor, the refrigerant compressor comprising: a recirculation path that communicates a space with the evaporator, and the recirculation port is located vertically below the protrusion.

The refrigerant compressor of the present disclosure is [2] "The refrigerant compressor according to [1], wherein the reflux path is constituted by the refrigerant flow path itself."

The refrigerant compressor of the present disclosure includes [3] "The bearing unit includes a pair of bearings that are arranged in parallel in the axial direction in which the shaft extends and supports the shaft in the radial direction, and the internal space is It has a first internal region, a second internal region, and a third internal region that communicate with each other in the axial direction, and the second internal region is located between the pair of bearings in the axial direction, and the second internal region is located between the pair of bearings in the axial direction, and The internal region is located on one side across the pair of bearings in the axial direction, the third internal region is located on the other side across the pair of bearings in the axial direction, and the suction port is The refrigerant compressor according to [1] or [2], wherein the refrigerant compressor communicates with the third internal region, and the discharge hole communicates with the first internal region.

The refrigerant compressor of the present disclosure includes [4] "The refrigerant compressor according to any one of [1] to [3], wherein the reflux path penetrates the housing from the internal space downward in the vertical direction. machine.”

[5] The refrigerant compressor according to [4], "The discharge hole penetrates the housing downward in the vertical direction from the internal space at a position different from the reflux path. Refrigerant compressor.”

The refrigerant compressor of the present disclosure provides the refrigerant compressor according to [5], wherein [6] "The inner wall surface of the housing includes an inclined part that descends toward the recirculation port between the discharge hole and the recirculation path. Compressor.”

[7] The refrigerant compressor according to any one of [1] to [4], wherein the discharge hole penetrates the housing upward in the vertical direction from the internal space. machine.”

2, 2A, 2B Refrigerant compressor 3 Condenser 5 Evaporator 6 Refrigerant circulation system 10

Shaft

11, 11A Housing 11a

Inner wall surface

12, 12A Suction hole (refrigerant flow path, reflux path)
12a Suction port (reflux port)
12b Reflux port 12B Reflux hole (reflux path)
13,13A Discharge hole 35 Impeller (projection)
60, 64 Bearing (bearing unit)
65 Thrust collar (projection)
D1A Upper D1B Lower D2 Axial direction F4 Flow path (refrigerant flow path, return flow path)
P1 Inclined part RB Rotating body S Internal space S1 First internal area S2 Second internal area S3 Third internal area

Claims

A refrigerant compressor that compresses refrigerant circulating in a refrigerant circulation system,
a rotating body having a shaft, and a protrusion that protrudes radially from the shaft and rotates together with the shaft;
a non-contact bearing unit that rotatably supports the rotating body;
a housing having an internal space that accommodates the protrusion;
an inlet opening into the internal space and supplying the refrigerant to the internal space;
a refrigerant flow path communicating with the suction port and connected to an evaporator;
a discharge hole for discharging the refrigerant from the internal space;
a reflux path that communicates the internal space and the evaporator via a reflux port provided in the internal space,
In the refrigerant compressor, the reflux port is located vertically lower than the protrusion.
The refrigerant compressor according to claim 1, wherein the reflux path is constituted by the refrigerant flow path itself.
The bearing unit includes a pair of bearings that are arranged side by side in an axial direction in which the shaft extends and support the shaft in a radial direction,
The internal space has a first internal area, a second internal area, and a third internal area that communicate with each other in the axial direction,
The second internal region is located between the pair of bearings in the axial direction,
The first internal region is located on one side of the pair of bearings in the axial direction,
The third internal region is located on the other side of the pair of bearings in the axial direction,
the suction port communicates with the third internal region,
The refrigerant compressor according to claim 1, wherein the discharge hole communicates with the first internal region.
The refrigerant compressor according to claim 1, wherein the recirculation path passes through the housing from the internal space downward in the vertical direction.
The refrigerant compressor according to claim 4, wherein the discharge hole penetrates the housing downward in the vertical direction from the internal space at a position different from the reflux path.
The refrigerant compressor according to claim 5, wherein the inner wall surface of the housing includes an inclined portion that descends toward the recirculation port between the discharge hole and the recirculation path.
The refrigerant compressor according to claim 1, wherein the discharge hole passes through the housing upward in the vertical direction from the internal space.