Impeller and shaft position sensor configurations for refrigerant compressor

Abstract

A refrigerant compressor may include a first compression stage, a second compression stage downstream of the first compression stage, and a third compression stage downstream of the second compression stage. Impellers of the second and third compression stages may be of a lesser diameter than an impeller of the first compression stage. Further, an axial position sensor may be arranged adjacent a shaft and the third compression stage.

Description

IMPELLER AND SHAFT POSITION SENSOR CONFIGURATIONS FOR REFRIGERANT COMPRESSORBACKGROUND

[0001] Refrigerant compressors are used to circulate refrigerant in a chiller via a refrigerant loop. Refrigerant loops are known to include a compressor, a condenser, an expansion device, and an evaporator. The compressor compresses the fluid, which then travels to the condenser, which in turn cools and condenses the fluid. The refrigerant then goes to the expansion device, which decreases the pressure of the fluid, and to the evaporator, where the fluid is vaporized, completing a refrigeration cycle.SUMMARY

[0002] In some aspects, the techniques described herein relate to a refrigerant compressor, including: a first compression stage, a second compression stage downstream of the first compression stage, and a third compression stage downstream of the second compression stage, wherein impellers of the second and third compression stages are of a lesser diameter than an impeller of the first compression stage.

[0003] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein two of the first, second, and third compression stages are on an opposite axial side of a motor as the other one of the first, second, and third compression stages.

[0004] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein the first compression stage is on a first axial side of the motor, and the second and third compression stages are on a second axial side of the motor opposite the first axial side.

[0005] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein the first and second compression stages are on a first axial side of a motor,and the third compression stage is on a second axial side of the motor opposite the first axial side.

[0006] In some aspects, the techniques described herein relate to a refrigerant compressor, further including an interstage pipe coupled to an exterior housing assembly of the refrigerant compressor and configured to transport refrigerant between compression stages on opposite axial sides of the motor.

[0007] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein an impeller of the third compression stage is of a lesser diameter than an impeller of the second compression stage.

[0008] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein impellers of the second and third compression stages exhibit a substantially equal diameter.

[0009] In some aspects, the techniques described herein relate to a refrigerant compressor, further including an axial position sensor mounted adjacent a shaft and adjacent the third compression stage.

[0010] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein the axial position sensor is configured to generate a signal indicative of an axial position between the axial position sensor and a hub projecting radially outward from an outer surface of the shaft.

[0011] In some aspects, the techniques described herein relate to a refrigerant compressor, including: a motor configured to rotate a shaft; a first compression stage, a second compression stage downstream of the first compression stage, and a third compression stage downstream of the second compression stage; and an axial position sensor of a magnetic bearing assembly mounted adjacent the shaft and adjacent the third compression stage.

[0012] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein the axial position sensor is configured to generate a signal indicative of an axial position between the axial position sensor and a hub projecting radially outward from an outer surface of the shaft.

[0013] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein impellers of the second and third compression stages are of a lesser diameter than an impeller of the first compression stage.

[0014] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein an impeller of the third compression stage is of a lesser diameter than an impeller of the second compression stage.

[0015] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein impellers of the second and third compression stages exhibit a substantially equal diameter.

[0016] In some aspects, the techniques described herein relate to a refrigerant compressor, wherein two of the first, second, and third compression stages are on an opposite axial side of the motor as the other one of the first, second, and third compression stages.

[0017] In some aspects, the techniques described herein relate to a method, including: detecting an axial position of a shaft of a refrigerant compressor including a first compression stage, a second compression stage downstream of the first compression stage, and a third compression stage downstream of the second compression stage, wherein the axial position of the shaft is detected using an axial position sensor mounted adjacent the shaft and adjacent the third compression stage.

[0018] In some aspects, the techniques described herein relate to a method, wherein the axial position sensor is configured to generate a signal indicative of an axial positionbetween the axial position sensor and a hub projecting radially outward from an outer surface of the shaft.

[0019] In some aspects, the techniques described herein relate to a method, further including: compressing refrigerant using the refrigerant compressor.

[0020] In some aspects, the techniques described herein relate to a method, wherein two of the first, second, and third compression stages are on an opposite axial side of the motor as the other one of the first, second, and third compression stages.

[0021] In some aspects, the techniques described herein relate to a method, wherein impellers of the second and third compression stages are of a lesser diameter than an impeller of the first compression stage.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 schematically illustrates a refrigerant system.

[0023] Figure 2 is a cross-sectional view of an example compressor taken along line 2-2 in Figure 3.

[0024] Figure 3 is an exterior view of the example compressor.

[0025] Figure 4 is a cross-sectional view of another example compressor.

[0026] Figure 5 illustrates an arrangement of impellers relative to a shaft corresponding to the embodiment of Figure 2.

[0027] Figure 6 illustrates an arrangement of impellers relative to a shaft corresponding to the embodiment of Figure 4.DETAILED DESCRIPTION

[0028] This disclosure relates generally to impeller and shaft position sensor configurations for refrigerant compressors, and more particularly to centrifugal refrigerant compressors. In a particular example, the disclosed refrigerant compressor includes threecompression stages, with downstream compression stages including smaller impellers than the upstream stages. Further, the disclosed refrigerant compressor arranges shaft position sensors adjacent the downstream -most compression stage. The assemblies, systems, and methods disclosed herein have been found to increase the compression ratio of the compressor, improve efficiency, and increase reliability, among other benefits.

[0029] Figure 1 illustrates a refrigerant system 10. The refrigerant system 10 includes a main refrigerant loop, or circuit, 12 in communication with a compressor 14, a condenser 16, an evaporator 18, and an expansion device 20. This refrigerant system 10 may be used in a chiller, for example. In that example, a cooling tower may be in fluid communication with the condenser 16. While a particular example of the refrigerant system 10 is shown, this application extends to other refrigerant system configurations, including configurations that do not include a chiller. Further, in Figure 1, a portion of the fluid leaving the condenser 16 may return to the compressor 14 through an economizer 22. Fluid from the economizer 22 is relatively high pressure, and, in this example, is introduced into the compressor 14 at one or more locations in order to cool or partially compress the low-pressure fluid within the compressor 14, thereby reducing the amount of work required by the compressor 14 to achieve the desired pressure and temperature, resulting in energy savings and increased efficiency.

[0030] Figure 2 illustrates, in cross-section, a portion of an example compressor 14, taken along line 2-2 of Figure 3, which is an exterior view of the example compressor 14. With joint reference to Figures 2 and 3, the compressor 14 includes an exterior housing assembly 24, which includes a plurality of housing sections. The exterior housing assembly 24 surrounds, among other components, an electric motor 26, a first compression stage 28, a second compression stage 30, and a third compression stage 32. The compressor 14 is a centrifugalcompressor, and in particular is configured to compress refrigerant. Therefore, the compressor 14 is a three-stage centrifugal refrigerant compressor.

[0031] The electric motor 26 includes a stator 34 arranged radially outside of a rotor 36. The rotor 36 is connected to a shaft 38, which rotates to drive the first, second, and third compression stages 28, 30, 32. In this disclosure, each compression stage 28, 30, 32 includes a respective impeller 40, 42, 44.

[0032] As shown in Figure 2, the first compression stage 28 is located on a first axial side of the electric motor 26, while the second and third compression stages 30, 32 are located on a second, opposite axial side of the electric motor 26.

[0033] In other embodiments, two compression stages are located on the first side of the electric motor 26, and a single compression stage is located on the second side of the electric motor 26. Specifically, as shown in Figure 4, the first and second compression stages 28, 30 are located on the first axial side of the electric motor 26, while the third compression stage 32 is located on the second, opposite axial side of the electric motor 26.

[0034] With reference back to Figures 2 and 3, the shaft 38 and impellers 40, 42, 44 are rotatable by the electric motor 26 about an axis A to compress refrigerant F. The terms axial, radial, and circumferential in this disclosure are used relative to the axis A. The shaft 38 may be rotatably supported by a plurality of bearing assemblies, which in some examples are magnetic bearing assemblies.

[0035] During operation of the compressor 14, refrigerant F flows axially toward the impeller 40 of the first compression stage 28 and is expelled radially outwardly to a diffuser 46 downstream of the impeller 40. The diffuser 46 is arranged radially between the outlet of the impeller 40 and a volute 48.

[0036] Refrigerant F expelled from volute 48 enters an interstage pipe 50. The interstage pipe 50 is configured to transport refrigerant F from the first compression stage 28to the second compression stage 30. As perhaps best seen in Figure 3, the interstage pipe 50 is attached to the exterior housing assembly 24.

[0037] With reference back to Figure 2, refrigerant F expelled from the interstage pipe 50 is introduced back into the exterior housing assembly 24 and directed to an inlet of the second compression stage 30. The second compression stage 30 expels refrigerant F, which is turned via a return channel 58 and directed to the third compression stage 32. In the embodiment of Figure 4, the return channel 58 is arranged between the first and second compression stages 28, 30. With reference back to Figures 2 and 3, the third compression stage 32 expels fluid F to another volute 60, which expels fluid to a compressor discharge 62 (Figure 3). Refrigerant F flows from compressor discharge 62 to the condenser 16.

[0038] In an aspect of this disclosure, the impellers associated with downstream compression stages are smaller, and in particular exhibits lesser diameters, than the impellers of upstream compression stages. For instance, with reference to Figure 5, which is representative of the arrangement of the impellers 40, 42, 44 of the first compression stages 28, 30, 32 of the embodiment of Figure 2, impeller 40 exhibits a first diameter DI, impeller 42 exhibits a second diameter D2, and impeller 44 exhibits a third diameter D3. First diameter DI is greater than both second diameter D2 and third diameter D3, in this example. Further, in this example, third diameter D3 is less than second diameter D2. In another example, diameters D2 and D3 may be equal.

[0039] Figure 6 is representative of the arrangement of the impellers 40, 42, 44 of the first compression stages 28, 30, 32 of the embodiment of Figure 4. With reference to Figure 6, impeller 40 exhibits a first diameter DI, impeller 42 exhibits a second diameter D2, and impeller 44 exhibits a third diameter D3. First diameter D 1 is greater than both second diameter D2 and third diameter D3, in this example. Further, in this example, third diameter D3 is less than second diameter D2. In another example, diameters D2 and D3 may be equal.

[0040] As the third compression stage 32 is downstream of the other two compression stages, refrigerant F exhibits a relatively increased temperature within the third compression stage 32 as compared to the first and second compression stages 28, 30. Due to the exposure of the third compression stage 32 to relatively high temperatures, the shaft 38 adjacent the third compression stage 32 may be subject to thermal -induced dimensional changes or thermal -induced displacements. As such, in an aspect of this disclosure, an axial position sensor 64 of a magnetic bearing assembly is positioned adjacent the third compression stage 32, as represented in both Figures 5 and 6. The axial position sensor 64 is configured to detect the axial position of the shaft 38 by sensing a distance between the axial position sensor 64 and a hub 66 projecting radially outward from an outer surface 68 of the shaft 38. The axial position sensor 64 is configured to generate a signal indicative of the axial position of the shaft 38, including axial vibrations of the shaft. Such signals are then processed by a controller and used by the controller, such as when the controller determines if the magnetic bearings require adjusting in order to better position the shaft 38 for efficient operation of the compressor 14.

[0041] It should be understood that terms such as “axial,” “radial,” and “circumferential” are used above with reference to the normal operational attitude of the compressor 14. Further, these terms have been used herein for purposes of explanation, and should not be considered otherwise limiting. Terms such as “generally,” “substantially,” and “about” are not intended to be boundaryless terms, and should be interpreted consistent with the way one skilled in the art would interpret those terms.

[0042] Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. In addition, the various figures accompanying this disclosure are not necessarily to scale, and some featuresmay be exaggerated or minimized to show certain details of a particular component or arrangement.

[0043] One of ordinary skill in this art would understand that the above-described embodiments are exemplary and non-limiting. That is, modifications of this disclosure would come within the scope of the claims. Accordingly, the following claims should be studied to determine their true scope and content.

Claims

CLAIMS1. A refrigerant compressor, comprising: a first compression stage, a second compression stage downstream of the first compression stage, and a third compression stage downstream of the second compression stage, wherein impellers of the second and third compression stages are of a lesser diameter than an impeller of the first compression stage.

2. The refrigerant compressor as recited in claim 1, wherein two of the first, second, and third compression stages are on an opposite axial side of a motor as the other one of the first, second, and third compression stages.

3. The refrigerant compressor as recited in claim 2, wherein the first compression stage is on a first axial side of the motor, and the second and third compression stages are on a second axial side of the motor opposite the first axial side.

4. The refrigerant compressor as recited in claim 2, wherein the first and second compression stages are on a first axial side of a motor, and the third compression stage is on a second axial side of the motor opposite the first axial side.

5. The refrigerant compressor as recited in claim 2, further comprising an interstage pipe coupled to an exterior housing assembly of the refrigerant compressor and configured to transport refrigerant between compression stages on opposite axial sides of the motor.

6. The refrigerant compressor as recited in claim 1, wherein an impeller of the third compression stage is of a lesser diameter than an impeller of the second compression stage.

7. The refrigerant compressor as recited in claim 1, wherein impellers of the second and third compression stages exhibit a substantially equal diameter.

8. The refrigerant compressor as recited in claim 1, further comprising an axial position sensor mounted adjacent a shaft and adjacent the third compression stage.

9. The refrigerant compressor as recited in claim 8, wherein the axial position sensor is configured to generate a signal indicative of an axial position between the axial position sensor and a hub projecting radially outward from an outer surface of the shaft.

10. A refrigerant compressor, comprising: a motor configured to rotate a shaft; a first compression stage, a second compression stage downstream of the first compression stage, and a third compression stage downstream of the second compression stage; and an axial position sensor of a magnetic bearing assembly mounted adjacent the shaft and adjacent the third compression stage.

11. The refrigerant compressor as recited in claim 10, wherein the axial position sensor is configured to generate a signal indicative of an axial position between the axial position sensor and a hub projecting radially outward from an outer surface of the shaft.

12. The refrigerant compressor as recited in claim 10, wherein impellers of the second and third compression stages are of a lesser diameter than an impeller of the first compression stage.

13. The refrigerant compressor as recited in claim 12, wherein an impeller of the third compression stage is of a lesser diameter than an impeller of the second compression stage.

14. The refrigerant compressor as recited in claim 12, wherein impellers of the second and third compression stages exhibit a substantially equal diameter.

15. The refrigerant compressor as recited in claim 10, wherein two of the first, second, and third compression stages are on an opposite axial side of the motor as the other one of the first, second, and third compression stages.

16. A method, comprising: detecting an axial position of a shaft of a refrigerant compressor including a first compression stage, a second compression stage downstream of the first compression stage, and a third compression stage downstream of the second compression stage, wherein the axial position of the shaft is detected using an axial position sensor mounted adjacent the shaft and adjacent the third compression stage.

17. The method as recited in claim 16, wherein the axial position sensor is configured to generate a signal indicative of an axial position between the axial position sensor and a hub projecting radially outward from an outer surface of the shaft.

18. The method as recited in claim 16, further comprising: compressing refrigerant using the refrigerant compressor.

19. The method as recited in claim 16, wherein two of the first, second, and third compression stages are on an opposite axial side of the motor as the other one of the first, second, and third compression stages.

20. The method as recited in claim 16, wherein impellers of the second and third compression stages are of a lesser diameter than an impeller of the first compression stage.

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