Compressor

Abstract

A compressor is provided with: a rotating shaft; an impeller that is attached to the rotating shaft and compresses the supplied fluid; a turbine attached to the rotating shaft; a first flow path forming member that forms a first flow path that guides a portion of the fluid compressed by the impeller to the turbine; and a second flow path forming member that forms a second flow path that guides the fluid after acting on the turbine to the fluid intake port of the impeller.

Description

Technical Field

[0001] The present disclosure relates to a compressor that compresses a fluid by the driving force of an electric motor. Background Art

[0002] For example, patent documents 1 to 3 disclose a compressor for compressing fluid. Such a compressor is provided with a circulation flow path that returns a portion of the fluid discharged from the outlet of the vortex flow path to the fluid inlet of the impeller. Thus, in the compressor, the flow rate of the fluid flowing in the aerodynamic components (impeller and vortex flow path) is increased to avoid surge, etc. In addition, there is a compressor that compresses the fluid by driving the impeller with an electric motor.

[0003] Patent Document 1: Japanese Patent Application No. 2008-531975

[0004] Patent Document 2: Japanese Patent Application Publication No. 2010-174806

[0005] Patent Document 3: Japanese Patent Application No. 2021-532300

[0006] In a compressor using an electric motor, when the flow rate of the fluid flowing through the aerodynamic component is increased using the above-mentioned circulation flow path, the power of the electric motor is increased by an amount corresponding to the increased fluid, which is considered to cause a decrease in compressor efficiency in the compressor. Summary of the invention

[0007] Therefore, the present disclosure describes a compressor that can increase the flow rate of a fluid flowing through an aerodynamic component while suppressing a decrease in compressor efficiency.

[0008] A compressor of one embodiment of the present invention compresses a fluid by the driving force of an electric motor, wherein the compressor comprises: a rotating shaft driven by the electric motor; an impeller mounted on the rotating shaft for compressing the supplied fluid; a turbine mounted on the rotating shaft; a first flow path forming component for forming a first flow path for guiding a portion of the fluid compressed by the impeller to the turbine; and a second flow path forming component for forming a second flow path for guiding the fluid after acting on the turbine to the fluid inlet of the impeller.

[0009] According to one aspect of the present disclosure, it is possible to increase the flow rate of the fluid flowing through the aerodynamic component while suppressing a decrease in compressor efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view schematically showing the structure of the compressor according to the embodiment.

[0011] Figure 2 It is a block diagram of a valve control device for a compressor.

[0012] Figure 3 It is a cross-sectional view schematically showing the structure of a compressor according to a modified example. DETAILED DESCRIPTION

[0013] A compressor of one embodiment of the present invention compresses a fluid by the driving force of an electric motor, wherein the compressor comprises: a rotating shaft driven by the electric motor; an impeller mounted on the rotating shaft for compressing the supplied fluid; a turbine mounted on the rotating shaft; a first flow path forming component for forming a first flow path for guiding a portion of the fluid compressed by the impeller to the turbine; and a second flow path forming component for forming a second flow path for guiding the fluid after acting on the turbine to the fluid inlet of the impeller.

[0014] The compressor is capable of increasing the flow rate of the fluid flowing in the aerodynamic component by providing a first flow path and a second flow path. In addition, a portion of the fluid compressed by the impeller is guided to the turbine by the first flow path. Thus, in the compressor, the turbine can be driven by the fluid returning to the aerodynamic component in order to increase the flow rate. By driving the turbine with the fluid, the impeller mounted on the rotating shaft is also driven. That is, in the compressor, a portion of the power of the increased flow rate of the fluid flowing in the aerodynamic component is recovered by the turbine, thereby suppressing the increase in the power of the electric motor. Thus, the compressor can suppress the reduction in compressor efficiency and increase the flow rate of the fluid flowing in the aerodynamic component.

[0015] In the above compressor, the electric motor may also be arranged in the second flow path. In this case, the compressor can cool the electric motor by means of the fluid flowing in the second flow path. Thus, the compressor can suppress the heating of the electric motor and further suppress the reduction of the compressor efficiency.

[0016] The compressor may further include: a valve provided in the first flow path forming member to adjust the flow rate of the fluid flowing in the first flow path; a temperature acquisition unit to acquire the motor temperature of the electric motor; and a valve control unit to control the valve based on the acquired motor temperature, wherein the valve control unit controls the valve in such a manner that the flow rate of the fluid flowing in the first flow path when the motor temperature is high is greater than the flow rate of the fluid flowing in the first flow path when the motor temperature is low. In this case, the compressor can more appropriately suppress the heating of the electric motor according to the motor temperature.

[0017] The above-mentioned compressor may also include a third flow path forming component, which forms a third flow path that guides the fluid supplied from the outside to the fluid inlet of the impeller, the electric motor is arranged in the third flow path, and the end of the downstream side of the second flow path is connected to the position between the electric motor and the fluid inlet in the third flow path. In this case, the fluid flowing in the second flow path is not affected by the heat of the electric motor. That is, the fluid acting on the turbine is supplied to the impeller without being heated up by the heat of the electric motor. As a result, the compressor can supply a fluid with a lower temperature to the impeller, which can improve the compression efficiency.

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are given to the same or corresponding components, and repeated descriptions are omitted.

[0019] like Figure 1 As shown in FIG. 1 , as an example, the compressor 10 is a two-stage compressor of a tandem type. The compressor 10 compresses a fluid supplied from the outside by the driving force of the electric motor 4. The compressor 10 includes a first impeller 1, a second impeller 2, a turbine 3, an electric motor 4, a rotating shaft 5, a casing 6, a return pipe 7, a valve 8, and a control unit 9 (see FIG. 1 ). Figure 2 ).

[0020] The first impeller 1, the second impeller 2, the turbine 3, and the electric motor 4 are accommodated in a housing 6. In addition, the housing 6 may be composed of a plurality of parts.

[0021] The first impeller (impeller) 1 and the second impeller 2 are respectively mounted on one end of the rotating shaft 5. The first impeller 1 and the second impeller 2 rotate integrally with the rotating shaft 5. The first impeller 1 and the second impeller 2 are arranged, for example, so that the back surfaces of each other face each other with a predetermined interval therebetween. The first impeller 1 and the second impeller 2 are arranged coaxially. The first impeller 1 is arranged between the second impeller 2 and the electric motor 4 on the rotating shaft 5. The first impeller 1 and the second impeller 2 compress the supplied fluid respectively.

[0022] A first fluid inlet (fluid inlet) H11 and a first vortex flow path H12 are formed in the casing 6 around the first impeller 1. The first fluid inlet H11 opens on the rotation axis of the rotating shaft 5. The first fluid inlet H11 introduces fluid into the first impeller 1. The first vortex flow path H12 extends around the first impeller 1 in a circumferential direction centered on the rotation axis of the rotating shaft 5. The first impeller 1 sucks fluid from the first fluid inlet H11 by rotating, and transports it to the first vortex flow path H12. The fluid sucked from the first fluid inlet H11 is compressed by the first impeller 1 and the first vortex flow path H12.

[0023] A second fluid inlet H21 and a second vortex flow path H22 are formed in the casing 6 around the second impeller 2. The second fluid inlet H21 opens on the rotation axis of the rotating shaft 5. The second fluid inlet H21 introduces fluid into the second impeller 2. The second vortex flow path H22 extends around the second impeller 2 in a circumferential direction centered on the rotation axis of the rotating shaft 5. The second impeller 2 sucks fluid from the second fluid inlet H21 by rotating. The second impeller 2 transports the sucked fluid to the second vortex flow path H22. The fluid sucked from the second fluid inlet H21 is compressed by the second impeller 2 and the second vortex flow path H22.

[0024] In the present embodiment, the discharge port of the first vortex flow path H12 on the first impeller 1 side and the second fluid inlet H21 on the second impeller 2 side are connected to each other through the connecting flow path L10. The connecting flow path L10 is formed by the housing 6. The first impeller 1 and the first vortex flow path H12 constitute a compression stage on the low-pressure side that sucks and compresses the fluid. The second impeller 2 and the second vortex flow path H22 constitute a compression stage on the high-pressure side that further compresses the fluid compressed by the compression stage on the low-pressure side.

[0025] The turbine 3 is mounted on the other end of the rotating shaft 5. The turbine 3 rotates integrally with the rotating shaft 5. The turbine 3 is coaxially arranged with the first impeller 1 and the second impeller 2. A turbine outlet H31 and a turbine vortex flow path H32 are arranged around the turbine 3 in the casing 6. The turbine outlet H31 opens on the rotation axis of the rotating shaft 5. The fluid after acting on the turbine 3 flows out from the turbine outlet H31. The turbine vortex flow path H32 extends in the circumferential direction of the turbine 3, centered on the rotation axis of the rotating shaft 5. The return flow path (first flow path) L1 described later is connected to the turbine vortex flow path H32. The turbine vortex flow path H32 guides the fluid introduced from the return flow path L1 to the turbine 3. The fluid guided to the turbine 3 causes the turbine 3 to rotate.

[0026] The electric motor 4 rotates the rotating shaft 5. That is, the rotating shaft 5 is driven (rotationally driven) by the electric motor 4. The electric motor 4 is disposed between the first impeller 1 and the turbine 3 on the rotating shaft 5.

[0027] Next, the flow path of the fluid provided in the compressor 10 is described in detail. A supply flow path (second flow path) L2 is formed in the housing (second flow path forming member) 6 around the rotating shaft 5 between the first impeller 1 and the turbine 3. The supply flow path L2 extends along the extension direction of the rotating shaft 5. The electric motor 4 and the rotating shaft 5 are arranged in the supply flow path L2. The end of the supply flow path L2 on the turbine 3 side is connected to the turbine outlet H31. The end of the supply flow path L2 on the first impeller 1 side is connected to the first fluid inlet H11.

[0028] The housing 6 is provided with an inlet flow path L3 through which the fluid supplied from the outside of the compressor 10 passes. The downstream end of the inlet flow path L3 is connected to a position on the upstream side of the electric motor 4 in the supply flow path L2 (a position between the electric motor 4 and the turbine outlet H31). Thus, the fluid supplied from the outside to the compressor 10 via the inlet flow path L3 and the fluid after acting on the turbine 3 are guided to the first fluid inlet H11 of the first impeller 1 by the supply flow path L2.

[0029] In addition, as described above, the electric motor 4 is arranged in the supply flow path L2. That is, the fluid flowing in the supply flow path L2 contacts the electric motor 4. Therefore, the compressor 10 can cool the electric motor 4 by the fluid flowing in the supply flow path L2. In addition, the electric motor 4 may not be entirely arranged in the supply flow path L2. At least a portion or a part of the components of the electric motor 4 may be arranged in the supply flow path L2. In addition, the arrangement of the electric motor 4 in the supply flow path L2 includes the case where at least a portion of the electric motor 4 is exposed to the supply flow path L2.

[0030] A discharge flow path L4 is formed in the housing 6. The discharge flow path L4 is connected to the second scroll flow path H22. Thus, the fluid compressed by the first impeller 1 and the second impeller 2 is discharged to the outside (outside the housing 6) via the discharge flow path L4. The fluid discharged from the discharge flow path L4 is supplied to the fluid supply object.

[0031] The return flow path L1 is connected to the discharge flow path L4 in a manner that branches from the discharge flow path L4. That is, one end of the return flow path L1 is connected to the discharge flow path L4. The other end of the return flow path L1 is connected to the turbine scroll flow path H32. In the present embodiment, the return flow path L1 is formed by a return pipe (first flow path forming component) 7 and a housing (first flow path forming component) 6 that forms a flow path in the vicinity of the turbine scroll flow path H32.

[0032] A portion of the fluid flowing in the discharge flow path L4 is guided to the turbine scroll flow path H32 via the return flow path L1, and further guided from the turbine scroll flow path H32 to the turbine 3. In this way, the return flow path L1 guides a portion of the fluid compressed by the first impeller 1 and the second impeller 2 to the turbine 3. The fluid guided to the turbine 3 rotates the turbine 3. As a result, the rotating shaft 5 rotates together with the turbine 3.

[0033] The valve 8 adjusts the flow rate of the fluid flowing in the return flow path L1. In the present embodiment, the valve 8 is provided in the return pipe 7 forming the return flow path L1.

[0034] like Figure 2As shown, the control unit 9 controls the valve 8 (controls the valve opening). The control unit 9 is composed of an electronic control unit including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory).

[0035] The control unit 9 functionally includes a temperature acquisition unit 91 and a valve control unit 92. The temperature acquisition unit 91 acquires the motor temperature of the electric motor 4. Here, the "motor temperature" may be the temperature of the electric motor 4 actually measured, or the temperature of the electric motor 4 estimated based on other values. For example, the temperature acquisition unit 91 may also acquire the temperature (measurement result) of the electric motor 4 measured by a non-contact temperature sensor or the like as the motor temperature. For example, the temperature of the fluid near the first fluid inlet H11 connected to the supply flow path L2 is correlated with the temperature of the electric motor 4. Therefore, the temperature acquisition unit 91 acquires the temperature of the fluid near the first fluid inlet H11 measured by the temperature sensor or the like. Moreover, the temperature acquisition unit 91 may also estimate the temperature of the electric motor 4 based on the acquired temperature, and acquire the estimated temperature as the motor temperature. In this way, the temperature acquisition unit 91 may also acquire the motor temperature based on the temperature of a portion that is correlated with the temperature of the electric motor 4.

[0036] The valve control unit 92 controls the valve opening of the valve 8 based on the motor temperature acquired by the temperature acquisition unit 91. More specifically, the valve control unit 92 controls the valve 8 so that the flow rate of the fluid flowing in the return flow path L1 when the motor temperature is high is greater than the flow rate of the fluid flowing in the return flow path L1 when the motor temperature is low.

[0037] As described above, the compressor 10 is provided with the return flow path L1 and the supply flow path L2, thereby being able to increase the flow rate of the fluid flowing in the aerodynamic component K constituted by the first impeller 1, the first scroll flow path H12, the second impeller 2, and the second scroll flow path H22. In addition, a part of the fluid compressed by the first impeller 1 and the second impeller 2 is guided to the turbine 3 by the return flow path L1. Thus, in the compressor 10, in order to increase the flow rate, the turbine 3 can be driven by the fluid returning to the aerodynamic component K. The turbine 3 is driven by the fluid, thereby also driving the first impeller 1 and the second impeller 2 mounted on the rotating shaft 5. That is, the compressor 10 recovers a part of the power of the amount of the increase in the flow rate of the fluid flowing in the aerodynamic component K by the turbine 3, thereby being able to suppress the increase in the power of the electric motor 4. Thus, the compressor 10 can suppress the reduction in compressor efficiency and increase the flow rate of the fluid flowing in the aerodynamic component K.

[0038] The electric motor 4 is disposed in the supply flow path L2. In this case, the compressor 10 can cool the electric motor 4 by the fluid flowing in the supply flow path L2. Thus, the compressor 10 can suppress the generation of heat in the electric motor 4 and further suppress a decrease in compressor efficiency.

[0039] The valve control unit 92 controls the valve 8 so that the flow rate of the fluid flowing in the return flow path L1 increases when the motor temperature is high. That is, the flow rate of the fluid flowing in the supply flow path L2 increases when the motor temperature is high compared to the flow rate of the fluid flowing in the supply flow path L2 when the motor temperature is low. In this case, the compressor 10 can more appropriately suppress the heat generation of the electric motor 4 according to the motor temperature.

[0040] Next, a modification of the flow path for guiding the fluid after acting on the turbine 3 to the first fluid inlet H11 of the first impeller 1 will be described. Figure 3 As shown, a first supply flow path (second flow path) L5 and a second supply flow path (third flow path) L6 are formed in the shell (second flow path forming member, third flow path forming member) 6 of the compressor 10A of this modified example, instead of the supply flow path L2 of the compressor 10 of the embodiment.

[0041] One end of the second supply flow path L6 is connected to the introduction flow path (third flow path) L3. The other end of the second supply flow path L6 is connected to the first fluid inlet H11 of the first impeller 1. The introduction flow path L3 and the second supply flow path L6 guide the fluid supplied from the outside of the compressor 10A to the first fluid inlet H11 of the first impeller 1. In this modification, the electric motor 4 is arranged in the second supply flow path L6.

[0042] One end of the first supply flow path L5 (the end on the upstream side of the fluid flow direction) is connected to the impeller outlet H31. The other end of the first supply flow path L5 (the end on the downstream side of the fluid flow direction) is connected to a position between the electric motor 4 and the first fluid inlet H11 in the second supply flow path L6. The first supply flow path L5 guides the fluid after acting on the turbine 3 to the first fluid inlet H11 of the first impeller 1 via the second supply flow path L6.

[0043] As described above, in the compressor 10A of this modification, the end of the downstream side of the first supply flow path L5 is connected to a position between the electric motor 4 and the first fluid inlet H11 of the first impeller 1 in the second supply flow path L6. In this case, the fluid flowing in the first supply flow path L5 is not affected by the heat of the electric motor 4. That is, the fluid acting on the turbine 3 is supplied to the first impeller 1 without being heated by the heat of the electric motor 4. As a result, the compressor 10A can supply a lower temperature fluid to the first impeller 1, and the compression efficiency can be improved.

[0044] The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments. For example, the compressors 10 and 10A are not limited to having two impellers, namely the first impeller 1 and the second impeller 2. The compressors 10 and 10A may also have one or more impellers.

[0045] In the compressors 10 and 10A, a part of the return flow path L1 is formed by the return pipe 7. However, the present invention is not limited thereto, and the return flow path L1 may be formed in the casing (first flow path forming member) 6 without using the return pipe 7.

[0046] Description of Reference Numerals

[0047] 1...first impeller (impeller); 3...turbine; 4...electric motor; 5...rotating shaft; 6...housing (first flow path forming component, second flow path forming component, third flow path forming component); 7...return piping (first flow path forming component); 8...valve; 10, 10A...compressor; 91...temperature acquisition unit; 92...valve control unit; H11...first fluid inlet (fluid inlet); L1...return flow path (first flow path); L2...supply flow path (second flow path); L3...inlet flow path (third flow path); L5...first supply flow path (second flow path); L6...second supply flow path (third flow path).

Claims

1. A compressor that compresses a fluid by the driving force of an electric motor, characterized in that: have: a rotating shaft driven by the electric motor; an impeller mounted on the rotating shaft to compress the supplied fluid; a turbine mounted on the rotating shaft; a first flow path forming member that forms a first flow path for guiding a portion of the fluid compressed by the impeller to the turbine; as well as The second flow path forming member forms a second flow path for guiding the fluid that has acted on the turbine to a fluid inlet of the impeller.

2. The compressor according to claim 1, characterized in that The electric motor is disposed in the second flow path.

3. The compressor according to claim 2, characterized in that Also available: a valve provided in the first flow path forming member and regulating a flow rate of the fluid flowing in the first flow path; a temperature acquisition unit that acquires a motor temperature of the electric motor; and a valve control unit that controls the valve based on the acquired motor temperature, The valve control unit controls the valve so that the flow rate of the fluid flowing through the first flow path when the motor temperature is high is greater than the flow rate of the fluid flowing through the first flow path when the motor temperature is low.

4. The compressor according to claim 1, characterized in that further comprising a third flow path forming member that forms a third flow path for guiding the fluid supplied from the outside to the fluid inlet of the impeller, The electric motor is arranged in the third flow path. The downstream end of the second flow path is connected to a position between the electric motor and the fluid inlet in the third flow path.

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