Compressors and refrigeration cycles

Abstract

To provide a compressor and refrigeration cycle that properly and efficiently cool a motor. [Solution] The system includes a refrigerant inlet 207 for drawing in the main refrigerant circulating in the refrigeration cycle, a refrigerant injection hole 219 for drawing in refrigerant bypassed from the refrigeration cycle to cool the motor 206, and a guide section 220 for changing the direction of flow of the refrigerant ejected from the refrigerant injection hole 219.

Description

Technical Field

[0001] The present invention relates to a compressor for cooling a motor and a refrigeration cycle.

Background Art

[0002] In a screw compressor, a technique is known in which a refrigerant circulating in a refrigeration cycle is bypassed and taken into the compressor to cool the motor.

[0003] For example, Japanese Patent Application Laid-Open No. 2000-320907 (Patent Document 1) discloses a configuration of a compressor having a plurality of inlets for liquid refrigerant, and having a non-zero angle with respect to the flow direction of gas in which the injection direction faces the motor. According to Patent Document 1, the liquid refrigerant diffuses and is sufficiently mixed with the suction gas, enabling cooling of the entire motor without temperature deviation.

[0004] By the way, when cooling a motor, when refrigerant gas is introduced into the space (air gap) between the stator and the rotor of the motor, efficient cooling can be performed. However, in Patent Document 1, the configuration is such that the liquid refrigerant and the suction gas are mixed, and the mixed refrigerant also flows to locations other than the air gap (for example, the passage on the outer periphery of the motor), so efficient cooling could not be performed. Therefore, there has been a demand for a further technique for cooling the motor while improving the reliability of the compressor.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] This invention has been made in view of the problems in the prior art described above, and aims to provide a compressor and a refrigeration cycle that cool a motor appropriately and efficiently. [Means for solving the problem]

[0007] In other words, according to the present invention, A first refrigerant inlet that draws in the main refrigerant circulating in the refrigeration cycle, To cool the motor, the refrigerant bypassed from the refrigeration cycle is supplied to a second refrigerant inlet. A guide section that changes the direction of flow of the refrigerant ejected from the second refrigerant inlet, A compressor is provided that includes the following features. [Effects of the Invention]

[0008] According to the present invention, a compressor and refrigeration cycle that properly cool a motor can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram showing the schematic configuration of the refrigeration cycle including the screw compressor of this embodiment. [Figure 2] A cross-sectional view showing the structure of the screw compressor of this embodiment. [Figure 3] An enlarged cross-sectional view showing the detailed structure of the screw compressor of this embodiment. [Figure 4] A diagram illustrating the flow of refrigerant in this embodiment. [Figure 5] A perspective view showing the structure of the guide section in an example of this embodiment. [Figure 6] A perspective view showing the structure of the guide section in an example of this embodiment. [Figure 7] A diagram showing the structure of a screw compressor in another example of this embodiment. [Figure 8] A perspective view showing the structure of the guide section in another example of this embodiment. [Figure 9] A perspective view showing the structure of the guide section in another example of this embodiment.

Best Mode for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited to the embodiments described below. In each of the drawings referred to below, the same reference numerals are used for common elements, and the description thereof will be omitted as appropriate.

[0011] FIG. 1 is a diagram showing a schematic configuration of a refrigeration cycle 1 including a screw compressor 2 according to the present embodiment. As shown in FIG. 1, the refrigeration cycle 1 of the present embodiment includes a screw compressor 2, a condenser 3, an expansion valve 4, an evaporator 5, a solenoid valve 6, and a throttle portion 7. The refrigeration cycle 1 operates as a refrigeration cycle by circulating a refrigerant therein, and can perform refrigeration, air conditioning, and the like.

[0012] Hereinafter, the operation of the refrigeration cycle 1 will be described. The arrows in FIG. 1 indicate the flow of the refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the screw compressor 2 flows into the condenser 3. In the condenser 3, the refrigerant liquefies by heat exchange between the gas refrigerant and air.

[0013] The liquid refrigerant discharged from the condenser 3 expands in volume in the expansion valve 4 and becomes a low-temperature and low-pressure liquid refrigerant. The liquid refrigerant discharged from the expansion valve 4 flows into the evaporator 5.

[0014] In the evaporator 5, the refrigerant becomes a low-temperature and low-pressure gas refrigerant by heat exchange between the liquid refrigerant and air. The gas refrigerant discharged from the evaporator 5 is sucked into the screw compressor 2 again and compressed. By repeating this cycle, the refrigeration cycle 1 can perform operations such as refrigeration and air conditioning.

[0015] Note that the heat exchange between the refrigerant and air can be promoted by a fan (not shown) in the condenser 3 and the evaporator 5.

[0016] Further, as shown in FIG. 1, the refrigeration cycle 1 of the present embodiment can include a bypass circuit in which the refrigerant flow path branches between the condenser 3 and the expansion valve 4, and the refrigerant flows through the solenoid valve 6 and the throttle portion 7 to the screw compressor 2. The refrigerant flowing into the screw compressor 2 via the bypass circuit can cool the motor inside the screw compressor 2. The operation of the bypass circuit can be controlled by opening and closing the solenoid valve 6.

[0017] By opening the solenoid valve 6, due to the pressure difference between the refrigerant sucked into the screw compressor 2 from the evaporator 5 and the refrigerant flowing through the bypass circuit, a part of the refrigerant flowing between the condenser 3 and the expansion valve 4 can flow to the bypass circuit side and be introduced into the screw compressor 2. For example, when the temperature of the motor rises, the solenoid valve 6 can be opened to operate the bypass circuit and cool the motor. Also, in the throttle portion 7, the liquid refrigerant can be expanded, the pressure and temperature can be lowered to gasify, and then sucked into the screw compressor 2 to cool the motor.

[0018] Next, the structure of the screw compressor 2 will be described. FIG. 2 is a cross-sectional view showing the structure of the screw compressor 2 of the present embodiment.

[0019] The screw compressor 2 has a main casing 201, a motor casing 202 having a refrigerant suction port 207, a discharge casing 203, and an oil separator 204 having a refrigerant discharge port 213, which are connected in a sealed relationship with each other.

[0020] The motor casing 202 houses the motor 206. The motor 206 includes a stator 206a fixed inside the motor casing 202 and a rotor 206b rotatably provided inside the stator 206a.

[0021] The main casing 201 has a compression chamber 215 and an intake port 208 for introducing gas into the compression chamber 215. The compression chamber 215 houses a male rotor 205 and a female rotor (not shown) that are rotatably supported by roller bearings 209, 210, and 211 and ball bearings 212, and are meshed together. The upstream side of the refrigerant gas relative to the screw rotor is sometimes referred to as the low-pressure side, and the downstream side as the high-pressure side. The shaft of the male rotor 205 is directly connected to rotor 206b on the low-pressure side.

[0022] The discharge casing 203, which houses the roller bearings 211 and ball bearings 212, has a compression chamber 215 connected to an oil separator 204 integrally molded with the main casing 201, and a gas discharge passage 214 opening to the oil separator 204 is formed therein. The discharge casing 203 is fixed to the main casing 201 by fastening means such as bolts. A shielding plate 217 is attached to one end of the discharge casing 203 to close off the bearing chamber 216 that houses the roller bearings 211 and ball bearings 212. Oil supply passages are formed inside the main casing 201 and the discharge casing 203, and are configured to connect the oil reservoir 218 at the bottom of the main casing 201 to each bearing section.

[0023] Next, we will explain the flow of refrigerant gas and oil in the screw compressor 2.

[0024] Low-temperature, low-pressure refrigerant gas is drawn in through a refrigerant inlet 207 provided in the motor casing 202, passes through a gas passage provided between the motor 206 and the motor casing 202, and through an air gap between the stator 206a and the rotor 206b, and is drawn in through an intake port 208 formed in the main casing 201 into a compression chamber 215 formed by the meshing tooth surfaces of the male rotor 205 and female rotor (not shown) and the main casing 201.

[0025] Subsequently, the refrigerant gas is sealed in a compression chamber 215 formed by the meshing tooth surfaces of the male rotor 205 and female rotor (not shown) and the main casing 201 as the male rotor 205 connected to the motor 206 rotates. As the volume of the compression space in the compression chamber 215 decreases, the gas is gradually compressed, becoming a high-temperature, high-pressure gas that is discharged from the discharge casing 203 through the discharge passage 214 into the oil separator 204. Of the compression reaction forces acting on the male rotor 205 and female rotor (not shown) during compression, the radial load is supported by roller bearings 209, 210, and 211, and the thrust load is supported by ball bearing 212.

[0026] The oil for lubricating and cooling these bearings is supplied by differential pressure from an oil reservoir 218 located in the high-pressure section at the bottom of the main casing 201, through oil passages communicating with each bearing, and discharged into the oil separator 204 along with the compressed gas. The oil contained in the compressed refrigerant gas is separated by the oil separator 204 and stored in the oil reservoir 218 at the bottom of the main casing 201. After oil separation, the compressed refrigerant gas is discharged from the refrigerant outlet 213.

[0027] Furthermore, the low-temperature liquid refrigerant that flows through the bypass circuit is gasified in the throttle section 7 (see Figure 1) and then injected into the motor casing 202 through refrigerant injection holes 219 provided in the casing. The injected refrigerant gas has its flow path curved by the guide section 220 and flows through the air gap between the stator 206a and rotor 206b, thereby cooling the motor 206. Note that the refrigerant injected from the refrigerant injection holes 219 is at a lower temperature than the refrigerant drawn in from the refrigerant inlet 207 because it has passed through the bypass circuit.

[0028] Furthermore, the detailed configuration of the screw compressor 2 of this embodiment will be described with reference to Figure 3. Figure 3 is an enlarged cross-sectional view showing the detailed structure of the screw compressor 2 of this embodiment. Figure 3(A) is an enlarged view of area A, indicated by the dashed rectangle in Figure 2.

[0029] As shown in Figure 3(A), the stator 206a is configured with a motor coil 206c. The motor coil 206c is wound with highly conductive copper or aluminum wire, and the motor 206 is driven by the flow of current through it. As shown in Figure 3(A), the motor coil 206c has a motor coil end 206d and an inner circumferential surface 206e.

[0030] Here, the positional relationship between the refrigerant injection hole 219, the guide portion 220, and the motor coil 206c in this embodiment will be explained with reference to Figure 3(B). Figure 3(B) is a further enlarged view of Figure 3(A). Note that Figure 3(B) is a diagram illustrating the configuration of the refrigerant injection hole 219, the guide portion 220, and the motor coil 206c, and other components are not shown.

[0031] As shown in Figure 3(B), in this embodiment, the refrigerant injection hole 219 is preferably located upstream of the motor coil end 206d. By positioning the refrigerant injection hole 219 and the motor coil end 206d in the positional relationship shown in Figure 3(B), the refrigerant ejected from the refrigerant injection hole 219 can be prevented from directly hitting the motor coil 206c, thereby preventing damage to the motor coil 206c.

[0032] Furthermore, as shown in Figure 3(B), it is preferable that the guide portion 220 in this embodiment is provided such that the guide end position is located inside the inner circumferential surface 206e of the motor coil. By arranging the guide portion 220 and the inner circumferential surface 206e of the motor coil in the positional relationship shown in Figure 3(B), the refrigerant whose flow direction has been changed by the guide surface of the guide portion 220 can be prevented from directly contacting the motor coil 206c, thereby preventing damage to the motor coil 206c.

[0033] Furthermore, in this embodiment, in order to change the direction of flow of the refrigerant ejected from the refrigerant injection hole 219, an R-shaped section may be provided on the guide section 220, as shown in Figure 3(B). As shown in Figure 3(B), the R-shaped section can be provided between a surface (for example, the wall surface of the motor casing 202) that is in line with the direction of flow of the refrigerant ejected from the refrigerant injection hole 219 and the guide surface, and can be a curved surface configured to bend this direction by 90 degrees. The ejected refrigerant flows along the inner wall surface of the motor casing 202 due to the Coanda effect, its flow direction is bent at the R-shaped section, and it flows further along the surface of the guide section 220. By providing the R-shaped section, the direction of flow of the refrigerant can be smoothly changed, so that the refrigerant can flow along the guide surface and be supplied in a predetermined direction. Therefore, since the refrigerant can be supplied to the air gap, the motor 206 can be cooled properly and efficiently.

[0034] Next, the refrigerant flow in this embodiment will be described with reference to Figure 4. Figure 4 is a diagram illustrating the refrigerant flow in this embodiment. Figure 4(A) is a diagram showing the flow path of the refrigerant inside the screw compressor 2. Figure 4(B) is a view taken along the line CC in Figure 4(A).

[0035] The refrigerant drawn into the screw compressor 2 from the refrigerant inlet 207 is the main flow refrigerant (hereinafter referred to as "main flow refrigerant") that has passed through the evaporator 5. In Figure 4(A), the dashed arrows indicate the flow path of the main flow refrigerant. As shown in Figure 4(A), the main flow refrigerant mainly flows into the compression chamber 215 through a gas refrigerant passage provided between the inner wall surface of the motor casing 202 and the outer circumferential surface of the stator 206a (see Figure 4(B)).

[0036] Furthermore, the refrigerant drawn into the screw compressor 2 through the refrigerant injection hole 219 is the refrigerant that has passed through the bypass circuit (hereinafter referred to as "bypass refrigerant"). In Figure 4(A), the arrows shown by solid lines indicate the paths of the bypass refrigerant flow.

[0037] The bypass refrigerant ejected from the refrigerant injection hole 219 has its flow path bent along the guide section 220. Here, as shown in Figure 4(A), the direction in which the refrigerant injection hole 219 ejects the bypass refrigerant is perpendicular to the direction in which the main refrigerant is drawn in by the refrigerant inlet 207 (the direction indicated by the block arrow in Figure 4). The bypass refrigerant then flows along the guide surface of the guide section 220, causing its flow path to bend.

[0038] As shown in Figure 4(A), by changing the direction of flow of the bypass refrigerant ejected from the refrigerant injection hole 219 using the guide section 220, the bypass refrigerant can be supplied to a wider area of ​​the air gap (see Figure 4(B)), allowing for efficient cooling of the motor 206. Furthermore, by providing the guide section 220, mixing of the bypass refrigerant and the main refrigerant can be prevented, allowing for efficient cooling of the motor 206 with less refrigerant and improving the reliability of the screw compressor 2. In addition, as shown in Figure 4(A), by configuring the system so that the direction in which the bypass refrigerant is ejected and the direction in which the main refrigerant is drawn in are perpendicular, the bypass refrigerant can also be supplied to a wider area of ​​the air gap (see Figure 4(B)).

[0039] Next, an example of the structure of the guide section 220 will be described with reference to Figures 5 and 6. Figures 5 and 6 are perspective views showing the structure of the guide section 220 in this embodiment, and are perspective views cut along the BB arrow plane in Figure 3(A). In Figures 5 and 6, solid arrows indicate the flow of bypass refrigerant, and dashed arrows indicate the flow of main stream refrigerant.

[0040] First, let's explain Figure 5. In the example shown in Figure 5, the guide section 220 can have a semi-cylindrical guide surface. As shown in Figure 5, the bypass refrigerant ejected from the refrigerant injection hole 219 flows along the inner wall of the motor casing 202, then its flow path is curved by the R section of the guide section 220, and it proceeds while diffusing along the semi-cylindrical guide surface. After passing through the end of the guide section 220, it flows into the air gap and cools the motor 206. The main refrigerant is drawn in from the refrigerant inlet 207 and proceeds inside the compressor, but as shown in Figure 5, it flows in an area where the flow of bypass refrigerant is small, so the main refrigerant and the bypass refrigerant do not mix, and the motor 206 can be cooled efficiently.

[0041] Next, Figure 6 will be explained. As shown in Figure 6, the guide portion 220 can have a flat guide surface. As shown in Figure 6, the bypass refrigerant ejected from the refrigerant injection hole 219 flows along the inner wall of the motor casing 202, then its flow path is curved by the R portion of the guide portion 220, and it proceeds while diffusing along the flat guide surface. After passing the end of the guide portion 220, it flows into the air gap and cools the motor 206. The main refrigerant is drawn in from the refrigerant inlet 207 and proceeds inside the compressor, but as shown in Figure 6, it flows in an area where the flow of bypass refrigerant is small, so the main refrigerant and the bypass refrigerant do not mix, and the motor 206 can be cooled efficiently.

[0042] Furthermore, in the examples of embodiments described so far, the refrigerant injection hole 219 was provided at the top of the screw compressor 2, but this does not particularly limit the embodiments. Therefore, in another example of this embodiment, the refrigerant injection hole 219 may be provided at a location other than the top.

[0043] Figure 7 shows the structure of a screw compressor 2 in another example of this embodiment. In describing the structure of the screw compressor 2 shown in Figure 7, explanations of points that are common to those described in Figure 2 will be omitted as appropriate.

[0044] The screw compressor 2 shown in Figure 7 differs from the screw compressor 2 shown in Figure 2 in that the refrigerant injection hole 219 is located at the bottom of the compressor, and the bypass refrigerant is ejected into the compressor from below in an upward direction. In addition, in the screw compressor 2 shown in Figure 7, due to the placement of the refrigerant injection hole 219 at the bottom, the guide section 220 is also positioned so that the direction of the refrigerant ejected from below is directed towards the air gap.

[0045] Next, an example of the structure of the guide section 220 in the configuration of Figure 7 will be described with reference to Figures 8 and 9. Figures 8 and 9 are perspective views showing the structure of the guide section 220 in this embodiment, and are perspective views cut along the DD arrow plane in Figure 7. In Figures 8 and 9, solid arrows indicate the flow of bypass refrigerant, and dashed arrows indicate the flow of main stream refrigerant.

[0046] First, let's explain Figure 8. In the example shown in Figure 8, similar to Figure 5, the guide section 220 can have a semi-cylindrical guide surface. As shown in Figure 8, the bypass refrigerant ejected from the refrigerant injection hole 219 flows along the inner wall of the motor casing 202, then its flow path is curved by the R section of the guide section 220, and it proceeds while diffusing along the semi-cylindrical guide surface. After passing through the end of the guide section 220, it flows into the air gap and cools the motor 206. The main refrigerant is drawn in from the refrigerant inlet 207 and proceeds inside the compressor, but as shown in Figure 8, it flows in an area with little bypass refrigerant flow (upper gas refrigerant passage side), so the main refrigerant and bypass refrigerant do not mix, and the motor 206 can be cooled efficiently with less refrigerant.

[0047] Next, Figure 9 will be explained. As shown in Figure 9, similar to Figure 6, the guide portion 220 can have a flat guide surface. As shown in Figure 9, the bypass refrigerant ejected from the refrigerant injection hole 219 flows along the inner wall of the motor casing 202, then the flow path is curved by the R portion of the guide portion 220, and it proceeds while diffusing along the flat guide surface. After passing the end of the guide portion 220, it flows into the air gap and cools the motor 206. The main refrigerant is drawn in from the refrigerant inlet 207 and proceeds inside the compressor, but as shown in Figure 9, it flows in an area with little bypass refrigerant flow (upper gas refrigerant passage side), so the main refrigerant and bypass refrigerant do not mix, and the motor 206 can be cooled efficiently.

[0048] According to the embodiments of the present invention described above, it is possible to provide a compressor and a refrigeration cycle that efficiently cool a motor.

[0049] Although the present invention has been described above with reference to embodiments, the present invention is not limited to the embodiments described above. It is included within the scope of the present invention as long as it achieves the effects and advantages of the present invention within the range of embodiments that a person skilled in the art could deduce. [Explanation of symbols]

[0050] 1…Refrigeration cycle, 2... Screw compressor, 3... Condenser, 4…Expansion valve, 5... Evaporator, 6... Solenoid valve, 7... Aperture section, 201...Main casing, 202... Motor casing, 203... Discharge casing, 204...Oil separator, 205... Male rotor, 206...motor, 206a... Stator, 206b... Rotor, 206c...motor coil, 206d... Motor coil end, 206e...Inner surface of motor coil, 207... Refrigerant intake port, 208... Inhalation port, 209... Roller bearings, 210... Roller bearings, 211... Roller bearings, 212...Ball bearing, 213...refrigerant discharge port, 214...Discharge passage, 215... Compression chamber, 216...Bearing chamber, 217...shielding plate, 218... Oil reservoir section, 219... Refrigerant injection hole, 220... Guide section

Claims

1. A first refrigerant inlet that draws in the main refrigerant circulating in the refrigeration cycle, To cool the motor, the refrigerant bypassed from the refrigeration cycle is supplied to a second refrigerant inlet. A guide section that changes the direction of flow of the refrigerant ejected from the second refrigerant inlet, A compressor equipped with a compressor.

2. The direction in which the refrigerant discharged into the compressor from the first refrigerant inlet flows and the direction in which the refrigerant discharged into the compressor from the second refrigerant inlet flows are perpendicular to each other. The compressor according to claim 1.

3. The second refrigerant inlet is located upstream of the end of the motor coil with respect to the direction of flow of the refrigerant drawn in from the first refrigerant inlet. The compressor according to claim 1.

4. The guide portion is provided such that the end of the guide portion is positioned inward from the inner circumferential surface of the motor coil. The compressor according to claim 1.

5. The guide portion is provided with a curved section that changes the direction of the refrigerant flow. The compressor according to claim 1.

6. The aforementioned guide portion is semi-cylindrical in shape. The compressor according to claim 1.

7. The guide portion is flat in shape. The compressor according to claim 1.

8. A refrigeration cycle comprising the compressor described in claim 1, a condenser, an expansion valve, and an evaporator.

9. The first refrigerant inlet is connected to the evaporator, The second refrigerant inlet is connected to a bypass circuit in which the refrigerant flow path is branched between the condenser and the expansion valve. The refrigeration cycle according to claim 8.

10. The bypass circuit includes a solenoid valve and a throttle section. The refrigeration cycle according to claim 9.

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