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Title:
FLUID FLOW CONTROL FOR A COMPRESSOR LUBRICATION SYSTEM
Document Type and Number:
WIPO Patent Application WO/2020/214807
Kind Code:
A1
Abstract:
A fluid pressure control system (110) for a compressor (32) includes a pump (90) configured to direct a lubricant toward a bearing (96) of the compressor (32), a sensor (112) configured to provide feedback indicative of a speed of a shaft (94) of the compressor (32), where the shaft (94) is configured to be at least partially supported by the bearing (96). The fluid pressure control system (110) also includes a non-transitory computer readable medium having executable instructions that, when executed by a processor (44), are configured to cause the processor (44) to receive a signal indicative of the speed of the shaft (94) from the sensor (112) and adjust operation of the pump (90) based on the signal.

Inventors:
SNELL PAUL (US)
SHEAFFER BRYSON (US)
HEISEY MATTHEW (US)
Application Number:
PCT/US2020/028502
Publication Date:
October 22, 2020
Filing Date:
April 16, 2020
Export Citation:
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Assignee:
JOHNSON CONTROLS TECH CO (US)
International Classes:
F04D27/02; F04B39/02; F04D29/063; F16N7/38
Foreign References:
US20070169997A12007-07-26
US20170207733A12017-07-20
US5180034A1993-01-19
US20170241307A92017-08-24
US6374950B12002-04-23
Attorney, Agent or Firm:
HENWOOD, Matthew, C. et al. (US)
Download PDF:
Claims:
CLAIMS:

1. A fluid pressure control system for a compressor, comprising:

a pump configured to direct a lubricant toward a bearing of the compressor;

a sensor configured to provide feedback indicative of a speed of a shaft of the compressor, wherein the shaft is configured to be at least partially supported by the bearing; and

a non-transitory computer readable medium comprising executable instructions that, when executed by a processor, are configured to cause the processor to:

receive a signal indicative of the speed of the shaft from the sensor; and adjust operation of the pump based on the signal.

2. The fluid pressure control system of claim 1, wherein the executable instructions, when executed by the processor, are configured to cause the processor to: determine a target flow rate of the lubricant based on the speed of the shaft; and adjust the operation of the pump, such that a flow rate of the lubricant toward the bearing of the compressor approaches the target flow rate.

3. The fluid pressure control system of claim 2, wherein the executable instructions, when executed by the processor, are configured to cause the processor to determine the target flow rate of the lubricant based on the speed of the shaft using a proportional function.

4. The fluid pressure control system of claim 2, wherein the executable instructions, when executed by the processor, are configured to cause the processor to determine the target flow rate of the lubricant based on the speed of the shaft using an exponential function.

5. The fluid pressure control system of claim 1, wherein the sensor is disposed proximate to an end of the shaft. 6 The fluid pressure control system of claim 1, comprising the bearing, wherein the lubricant is configured to form a film between the bearing and the shaft.

7. The fluid pressure control system of claim 1, wherein the pump comprises an electric pump.

8. The fluid pressure control system of claim 7, wherein the executable instructions, when executed by the processor, are configured to cause the processor to output a signal to the electric pump to adjust a flow rate of the lubricant to achieve a target flow rate.

9. A fluid pressure control system for a compressor, comprising:

a pump configured to direct a lubricant toward a bearing of the compressor;

a sensor configured to provide feedback indicative of a temperature in the compressor at the bearing; and

at least one non-transitory computer readable medium comprising executable instructions that, when executed by a processor, are configured to cause the processor to:

receive a signal indicative of the temperature in the compressor at the bearing from the sensor; and

adjust a speed of the pump based on the signal.

10. The fluid pressure control system of claim 9, comprising a lubrication circuit, wherein the pump and the compressor are disposed along the lubrication circuit, and wherein the lubrication circuit is configured to direct the lubricant from the pump toward the bearing and from the bearing toward the pump.

11. The fluid pressure control system of claim 10, wherein the sensor comprises a first sensor disposed along the lubrication circuit and configured output a first signal indicative of a fluid supply temperature of the lubricant along the lubrication circuit upstream of the bearing and a second sensor disposed along the lubrication circuit and configured to output a second signal indicative of a fluid drain temperature of the lubricant along the lubrication circuit downstream of the bearing.

12. The fluid pressure control system of claim 11, wherein the executable instructions, when executed by the processor, are configured to cause the processor to determine the temperature in the compressor at the bearing based on the fluid supply temperature and the fluid drain temperature.

13. The fluid pressure control system of claim 9, wherein the executable instructions, when executed by the processor, are configured to cause the processor to output a signal to an interface board to display the temperature in the compressor at the bearing on a display of the interface board.

14. The fluid pressure control system of claim 9, wherein the sensor is disposed proximate to the bearing.

15. The fluid pressure control system of claim 14, wherein the sensor comprises a thermocouple configured to output the signal indicative of the temperature in the compressor at the bearing.

16. A fluid pressure control system for a compressor, comprising:

a pump configured to direct a lubricant toward a bearing of the compressor;

a first sensor configured to provide feedback indicative of a speed of a shaft of the compressor, wherein the shaft is configured to be at least partially supported by the bearing; a second sensor configured to provide feedback indicative of a temperature in the compressor at the bearing; and at least one non-transitory computer readable medium comprising executable instructions that, when executed by a processor, are configured to cause the processor to:

receive a first signal indicative of the speed of the shaft from the first sensor;

receive a second signal indicative of the temperature in the compressor at the bearing from the second sensor; and

adjust a speed of the pump based on the first signal, the second signal, or both.

17. The fluid pressure control system of claim 16, wherein the executable instructions, when executed by the processor, are configured to cause the processor to determine a target flow rate of the fluid directed toward the bearing of the compressor by the pump.

18. The fluid pressure control system of claim 17, wherein the executable instructions, when executed by the processor, are configured to cause the processor to: determine a target speed of the pump that achieves the target flow rate; and compare the target speed of the pump that achieves the target flow rate to an operating range of speeds of the pump.

19. The fluid pressure control system of claim 17, wherein the executable instructions, when executed by the processor, are configured to cause the processor to: determine the target flow rate of the lubricant based on the temperature in the compressor at the bearing exceeding a target temperature range; and

adjust operation of the pump to cause the flow rate of the lubricant to approach the target flow rate.

20. The fluid pressure control system of claim 19, wherein the executable instructions, when executed by the processor, are configured to cause the processor to determine the target temperature range based on inputs received via an interface board.

Description:
FLUID FLOW CONTROL FOR A COMPRESSOR LUBRICATION SYSTEM

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from and the benefit of U.S. Provisional Application Serial No. 62/834,871, entitled “FLUID PRESSURE CONTROL FOR A COMPRESSOR,” filed April 16, 2019, which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0003] Heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) systems are used in a variety of settings and for many purposes. For example, HVAC&R systems may include a vapor compression refrigeration system (e.g., a refrigerant circuit having a condenser, an evaporator, a compressor, and/or an expansion device) configured to condition an environment. The vapor compression refrigeration system may include a lubrication circuit that directs lubrication fluid (e.g., oil) into the compressor to provide lubrication to various components (e.g., bearings) of the compressor. Conditions within the compressor, such as temperature and pressure, may vary during operation of the compressor. Unfortunately, existing HVAC&R systems may supply the lubrication fluid to the compressor at a constant pressure, which may cause the lubrication fluid to flow to unintended locations within the HVAC&R system as conditions vary within the compressor. SUMMARY

[0004] In an embodiment of the present disclosure, a fluid pressure control system for a compressor includes a pump configured to direct a lubricant toward a bearing of the compressor, a sensor configured to provide feedback indicative of a speed of a shaft of the compressor, where the shaft is configured to be at least partially supported by the bearing. The fluid pressure control system also includes a non-transitory computer readable medium having executable instructions that, when executed by a processor, are configured to cause the processor to receive a signal indicative of the speed of the shaft from the sensor and adjust operation of the pump based on the signal.

[0005] In an embodiment of the present disclosure, a fluid pressure control system for a compressor includes a pump configured to direct a lubricant toward a bearing of the compressor, a sensor configured to provide feedback indicative of a temperature in the compressor at the bearing, and at least one non-transitory computer readable medium having executable instructions that, when executed by a processor, are configured to cause the processor to receive a signal indicative of the temperature in the compressor at the bearing from the sensor and adjust a speed of the pump based on the signal.

[0006] In an embodiment of the present disclosure, a fluid pressure control system for a compressor includes a pump configured to direct a lubricant toward a bearing of the compressor, a first sensor configured to provide feedback indicative of a speed of a shaft of the compressor, and a second sensor configured to provide feedback indicative of a temperature in the compressor at the bearing. The shaft is configured to be at least partially supported by the bearing. The fluid pressure control system also includes at least one non-transitory computer readable medium having executable instructions that, when executed by a processor, are configured to cause the processor to receive a first signal indicative of the speed of the shaft from the first sensor, receive a second signal indicative of the temperature in the compressor at the bearing from the second sensor, and adjust a speed of the pump based on the first signal, the second signal, or both. DRAWINGS

[0007] FIG. 1 is a perspective view of a building that may utilize an embodiment of a heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0008] FIG. 2 is a perspective view of an embodiment of an HVAC&R system, in accordance with an aspect of the present disclosure;

[0009] FIG. 3 is a schematic diagram of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0010] FIG. 4 is a schematic diagram of another embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0011] FIG. 5 is a schematic diagram of an embodiment of a vapor compression system having a sump, in accordance with an aspect of the present disclosure;

[0012] FIG. 6 is a schematic diagram of an embodiment of a vapor compression system having a fluid pressure control system, in accordance with an aspect of the present disclosure;

[0013] FIG. 7 is a flow chart illustrating an embodiment of a process for operating a fluid pressure control system of a vapor compression system, in accordance with an aspect of the present disclosure;

[0014] FIG. 8 is a flow chart illustrating an embodiment of a process for operating a fluid pressure control system of a vapor compression system, in accordance with an aspect of the present disclosure; and

[0015] FIG. 9 is a flow chart illustrating an embodiment of a process for operating a fluid pressure control system of a vapor compression system, in accordance with an aspect of the present disclosure. DETAILED DESCRIPTION

[0016] One or more specific embodiments of the present disclosure will be described below. These described embodiments are only examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation- specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0017] As discussed above, a vapor compression system generally includes a refrigerant flowing through a refrigeration circuit. The refrigerant flows through multiple conduits and components disposed along the refrigeration circuit, while undergoing phase changes to enable the vapor compression system to condition an interior space of a structure. The vapor compression system generally includes a lubrication circuit having fluid (e.g., a lubricant, such as oil) flowing through certain components of the refrigeration circuit (e.g., a compressor, a sump, and a cooler) to provide lubrication for a compressor of the refrigeration circuit during operation. The compressor includes a shaft coupled to a rotor configured to compress the refrigerant within the compressor. The shaft is supported by at least one bearing, and the fluid of the lubrication circuit is configured to flow generally between the shaft and the bearing to lubricate the shaft as it rotates.

[0018] A pump of the lubrication circuit pumps the fluid from the sump to the compressor and along the lubrication circuit. Specifically, the fluid flows from the sump to the bearing and the shaft of the compressor. The pump may pump the fluid along the lubrication circuit (e.g., to the bearing) at a constant flow rate and/or at a constant pressure. During operation of the compressor, a shaft speed may vary due to certain factors, such as an operating mode of the compressor and/or operating conditions of the vapor compression system generally (e.g., a temperature and/or a pressure of the refrigerant flowing through the refrigerant circuit, operator input, or a combination thereof). Additionally or alternatively, a temperature of the lubrication fluid in the compressor and at the bearing may vary due to the operating mode of the compressor and/or the operating parameters of the vapor compression system generally (e.g., the temperature and/or the pressure of the refrigerant flowing through the refrigerant circuit, friction between the shaft and other components of the compressor (e.g., the rotors), or a combination thereof).

[0019] The compressor includes seals (e.g., hermetic seals and/or labyrinth seals) configured to seal the fluid flowing through and lubricating the components of the compressor (e.g., the bearing and/or the shaft). However, as the shaft speed and/or the temperature at the bearing vary, fluid flowing at a constant flow rate and/or a constant pressure may leak at the seals of the compressor. For example, if the shaft speed and/or the temperature are relatively low, a pressure of the fluid may increase within the compressor due to the fluid flowing along the bearing and/or the shaft at a constant flow rate, which may cause the fluid to leak at the seals. If the shaft speed and/or the temperature are relatively high, the fluid may not flow at a sufficient rate to adequately lubricate the bearing and/or the shaft (e.g., the constant flow rate of the fluid may be too low to properly lubricate the bearing and/or the shaft). The inadequate lubrication of the bearing and/or the shaft may cause the bearing, the shaft, and/or the compressor to overheat due to the increased friction. As such, the constant flow rate of the fluid along the lubrication circuit, along with the varying shaft speed and/or the varying temperature of the fluid within the compressor, may reduce an efficiency of the compressor and the vapor compression system.

[0020] Some examples of fluids that may be used as refrigerants in embodiments of the vapor compression system of the present disclosure are hydrofluorocarbon (HFC) based refrigerants, such as R-410A, R-407, or R-134a, hydrofluoroolefm (HFO) based refrigerants, such as R-1233 or R-1234,“natural” refrigerants, such as ammonia (MR), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based refrigerants, water vapor, or any other suitable refrigerant. In some embodiments, the vapor compression system may be configured to efficiently utilize refrigerants having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere of pressure, also referred to as low pressure refrigerants, as compared to a medium pressure refrigerant, such as R-134a. As used herein,“normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure. Some examples of fluids that may be used as lubricants in embodiments of the vapor compression system of the present disclosure are synthetic oils, mineral oils, or any other suitable lubricant.

[0021] The present disclosure is directed to a fluid pressure control system for a compressor of a vapor compression system. Certain embodiments of the fluid pressure control system include sensors that detect a shaft speed of the compressor and/or a temperature in the compressor at the bearing. For example, a first sensor may be disposed at the shaft to provide feedback indicative of the shaft speed and/or a second sensor may be disposed at the bearing to provide feedback indicative of the temperature in the compressor at the bearing. In certain embodiments, additional sensors may be disposed at a supply conduit of the compressor and/or at a drain conduit of the compressor to provide feedback indicative of a fluid supply temperature and a fluid drain temperature, respectively. Based on the fluid supply temperature and/or the fluid drain temperature, a controller of the fluid pressure control system may determine the temperature in the compressor at the bearing.

[0022] Based on the shaft speed and/or the temperature in the compressor at the bearing, the controller of the fluid pressure control system may adjust a flow rate of the fluid from the pump to the bearing (e.g., adjust a pressure of the fluid within the lubrication circuit). The controller may determine a target flow rate based on the shaft speed and/or the temperature and may adjust a speed of the pump, such that the flow rate of the fluid approaches the target flow rate. The target flow rate may be a function of the shaft speed and/or the temperature within the compressor at the bearing (e.g., a linear function, a non linear function, a proportional function, an exponential function, or a combination thereof). As the shaft speed and/or the temperature generally decrease, the controller may adjust the speed of the pump to reduce the flow rate of the fluid to a generally lower target flow rate. As the shaft speed and/or the temperature generally increase, the controller may adjust the speed of the pump to increase the flow rate of the fluid to a generally higher target flow rate. As the controller adjusts the flow rate of the fluid, operation and/or efficiency of the compressor and the vapor compression system generally may improve. For example, the adjustments to the flow rate of the fluid may at least partially block or reduce leakage of the fluid at the seals of the compressor and/or may reduce the friction between the fluid, the shaft, and/or the bearing.

[0023] The control techniques of the present disclosure may be used in a variety of systems. However, to facilitate discussion, examples of systems that may incorporate the control techniques of the present disclosure are depicted in FIGS. 1-4, which are described herein below.

[0024] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, and air conditioning (HVAC) system 10 in a building 12 for a typical commercial setting. The HVAC system 10 may include a vapor compression system 14 that supplies a chilled liquid, which may be used to cool the building 12. The HVAC system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and an air distribution system which circulates air through the building 12. The air distribution system can also include an air return duct 18, an air supply duct 20, and/or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or chilled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC system 10. The HVAC system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC system 10 may include air handlers 22 and/or other components that may be shared between or among floors.

[0025] FIGS. 2 and 3 illustrate embodiments of the vapor compression system 14 that can be used in the HVAC system 10. The vapor compression system 14 may circulate a refrigerant through a circuit starting with a compressor 32. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38. The vapor compression system 14 may further include a control panel 40 (e.g., a controller) that has an analog to digital (A/D) converter 42, a microprocessor 44, a non- volatile memory 46, and/or an interface board 48.

[0026] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and/or the evaporator 38. The motor 50 may drive the compressor 32 and may be powered by a variable speed drive (VSD) 52. The VSD 52 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be powered directly from an AC or direct current (DC) power source. The motor 50 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0027] The compressor 32 compresses a refrigerant vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The compressor 32 includes a fluid (e.g., a lubricant oil) that lubricates components of the compressor. The refrigerant vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The refrigerant vapor may condense to a refrigerant liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The refrigerant liquid from the condenser 34 may flow through the expansion device 36 to the evaporator 38. In the illustrated embodiment of FIG. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser.

[0028] The refrigerant liquid delivered to the evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser 34. The refrigerant liquid in the evaporator 38 may undergo a phase change from the refrigerant liquid to a refrigerant vapor. As shown in the illustrated embodiment of FIG. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a cooling load 62. The cooling fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via return line 60R and exits the evaporator 38 via supply line 60S. The evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via thermal heat transfer with the refrigerant. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and/or a plurality of tube bundles. In any case, the refrigerant vapor exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

[0029] FIG. 4 is a schematic diagram of the vapor compression system 14 with an intermediate circuit 64 incorporated between condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or a“surface economizer.” In the illustrated embodiment of FIG. 4, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e.g., expand) the refrigerant liquid received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. Additionally, the intermediate vessel 70 may provide for further expansion of the refrigerant liquid because of a pressure drop experienced by the refrigerant liquid when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor in the intermediate vessel may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid that collects in the intermediate vessel 70 may be at a lower enthalpy than the refrigerant liquid exiting the condenser 34 because of the expansion in the expansion device 66 and/or the intermediate vessel 70. The liquid from intermediate vessel 70 may then flow in line 72 through a second expansion device 36 to the evaporator 38. [0030] FIG. 5 is a schematic diagram illustrating an embodiment of a lubrication circuit 80 that may be included in the vapor compression system 14. As described above, the vapor compression system 14 may utilize a fluid (e.g., a lubricant, such as oil) that circulates through the compressor 32 to lubricate components (e.g., the bearings and/or the shaft) of the compressor 32. More specifically, the lubrication circuit 80 is configured to circulate the fluid to various locations along the vapor compression system 14, such as the compressor 32, to provide the fluid for lubrication of various components. The lubrication circuit 80 includes a sump 82 fluidly coupled to the compressor 32 to collect and/or store the fluid. After lubricating components of the compressor 32, the fluid flows toward the sump 82 via a compressor drain conduit 84 and may accumulate within the sump 82. As illustrated, the lubrication circuit 80 includes a condenser drain conduit 86 and an evaporator drain conduit 88 configured to discharge the fluid that mixes with refrigerant and collects within the condenser 34 and the evaporator 38, respectively, to the sump 82. For example, the condenser drain conduit 86 and/or the evaporator drain conduit 88 may be configured to direct the fluid (e.g., oil or an oil and refrigerant mixture) to the sump 82 as a high pressure gas. In certain embodiments, the fluid flowing along condenser drain conduit 86 and/or along the evaporator drain conduit 88 may flow through an eductor 89 prior to entering the sump 82. The eductor 89 may mix the fluids exiting the condenser 34 and the evaporator 38 prior to entering the sump 82 and/or may draw the fluids exiting the condenser 34 and the evaporator 38 toward the sump 82.

[0031] A pump 90 may be disposed within the sump 82 (e.g., a submersible pump and/or a variable speed pump) to direct the fluid or the mixture of fluid and refrigerant to the compressor 32 via a compressor supply conduit 92. In other embodiments, the pump 90 may be disposed outside the sump 82 and/or may be positioned between the sump 82 and the compressor 32. Additionally, in some embodiments, the lubrication circuit 80 may include a cooler disposed along the compressor drain conduit 84 and/or the compressor supply conduit 92. The cooler may be configured to remove heat from the fluid that the fluid previously absorbed when lubricating the compressor 32.

[0032] In certain embodiments, the pump 90 may be an electric pump having a variable speed, such that the pump 90 is configured to be adjusted to provide or enable a specific flow rate of the fluid. For example, the pump 90 may receive a signal indicative of an adjustment to the target flow rate of the fluid within the lubrication circuit 80 from a controller. The speed of the pump 90 may be adjusted based on the signal received to enable the flow of fluid through the pump 90 to achieve the target flow rate. As described herein, the adjustment to the target flow rate may include a proportional adjustment, a linear adjustment, a non-linear adjustment, an exponential adjustment, another type of adjustment to the flow rate, or a combination thereof. By comparison, a mechanically-driven pump (e.g., a pump driven to adjust a flow rate via a shaft) may be configured to adjust the flow rate linearly but not in other manners. As such, the flow rate of the fluid supplied by the pump 90 may be adjusted to a wider range of target flow rates when compared to a mechanically-driven pump.

[0033] In some embodiments, the pump 90 may be a fixed speed pump, and the flow rate downstream of the pump 90 may be adjusted via an electronic regulator or electronic bypass valve. For example, the electronic regulator or electronic bypass valve may be located between the pump 90 and the compressor 32 (e.g., along the compressor supply conduit 92). The electronic regulator or electronic bypass valve may receive the signal indicative of an adjustment to the target flow rate of the fluid within the lubrication circuit 80 from a controller. In response, operation of the electronic regulator or electronic bypass valve may be adjusted to enable the flow of fluid through the pump 90 to achieve the target flow rate.

[0034] FIG. 6 is a schematic diagram illustrating an embodiment of the lubrication circuit 80. As shown in the illustrated embodiment of FIG. 6, the compressor 32 includes a shaft 94 configured to rotate and cause rotors coupled to the shaft 94 to compress the refrigerant within the compressor 32. The shaft 94 is at least partially supported by a bearing 96. While the illustrated embodiment shows the compressor 32 having one bearing 96, in other embodiments, the compressor 32 may include additional bearings 96 configured to support the shaft 94 (e.g., two bearings, three bearings, four bearings, six bearings, ten bearings, etc.). The fluid (e.g., the oil or other lubricant) may flow between the shaft 94 and the bearing 96 such that a fluid film is formed between the shaft 94 and the bearing 96 to lubricate the shaft 94 as the shaft 94 rotates. The fluid may enter the compressor 32 via a compressor fluid inlet 98 coupled to the compressor supply conduit 92 and may generally be directed to bearing fluid inlets 100, as indicated by arrows 102. The fluid may flow from the bearing fluid inlets 100, between the shaft 94 and the bearing 96, and ultimately flow away from the bearing 96, as indicated by arrows 104 (e.g., at ends of the bearing 96). After passing through the bearing 96, the fluid may flow to a compressor fluid outlet 106 that is coupled to the compressor drain conduit 84. As such, the fluid may circulate from the sump 82, through the bearing 96, and back to the sump 82.

[0035] The vapor compression system 14 also includes a fluid pressure control system 110 configured to control the flow of fluid (e.g., lubricant) along the lubrication circuit 80. For example, portions of the lubrication circuit 80, and the vapor compression system 14 generally, may be controlled by the fluid pressure control system 110 based on feedback indicative of operating parameters of the vapor compression system 14. Specifically, the vapor compression system 14 may be controlled based on feedback indicative of a shaft speed (e.g., a rotational shaft speed) of the shaft 94 as detected by a sensor 112. The sensor 112 is disposed proximate to the shaft 94 and is communicatively coupled to the control panel 40, such that the sensor 112 may output a signal indicative of the shaft 94 speed to the control panel 40. Additionally or alternatively, the vapor compression system 14 may be controlled based on feedback indicative of a temperature of the fluid in the compressor 32 at the bearing 96, as detected by a sensor 114. The sensor 114 is disposed proximate to the bearing 96 and is communicatively coupled to the control panel 40, such that the sensor 114 may output a signal indicative of the temperature in the compressor 32 at the bearing 96 to the control panel 40. In some embodiments, the sensor 114 may be a thermocouple and/or another suitable device configured to provide feedback indicative of temperature that is disposed proximate to the bearing 96.

[0036] In certain embodiments, the fluid pressure control system 110 may include a sensor 116 that is disposed along the compressor supply conduit 92 (e.g., along the lubrication circuit 80 upstream of the bearing 96) and is configured to detect a fluid supply temperature of the fluid along the compressor supply conduit 92. Additionally or alternatively, the sensor 116 may be disposed at the compressor fluid inlet 98 and may be configured to detect the fluid supply temperature at the compressor fluid inlet 98. The sensor 116 is communicatively coupled to the control panel 40 and is configured to output a signal indicative of the fluid supply temperature to the control panel 40.

[0037] In certain embodiments, the fluid pressure control system 110 may include a sensor 118 that is disposed along the compressor drain conduit 84 (e.g., along the lubrication circuit 80 downstream of the bearing 96) and is configured to detect a fluid drain temperature of the fluid along the compressor drain conduit 84. Additionally or alternatively, the sensor 118 may be disposed at the compressor fluid outlet 106 and may be configured to detect the fluid drain temperature at the compressor fluid outlet 106. The sensor 118 is communicatively coupled to the control panel 40 and is configured to output a signal indicative of the fluid drain temperature to the control panel 40. Based on the feedback indicative of the fluid supply temperature and/or the fluid drain temperature, the microprocessor 44 of the control panel 40 (e.g., using instructions stored in the memory 46) may determine and/or calculate the temperature in the compressor 32 at the bearing 96. For example, the microprocessor 44 may calculate the temperature in the compressor 32 at the bearing 96 based on a difference between the fluid supply temperature and the fluid drain temperature or based on another suitable algorithm using the fluid supply temperature and the fluid drain temperature.

[0038] The microprocessor 44 may determine a target flow rate of the fluid flowing from the pump 90 to the bearing 96 based on the shaft speed of the shaft 94 and/or the temperature in the compressor at the bearing 96. For example, the microprocessor 44 may determine the target flow rate of the fluid as a function of the shaft speed and/or the temperature (e.g., a linear function, a non-linear function, a proportional function, an exponential function, or a combination thereof). Additionally or alternatively, the microprocessor 44 may determine the target flow rate based on reference tables stored in the memory 46. For example, the reference tables may list target flow rates as a function of corresponding shaft speeds and/or temperatures. In some embodiments, the microprocessor 44 may interpolate values within the reference tables to determine the target flow rate. In still further embodiments, the microprocessor 44 may determine the target flow rate based on inputs 130 to the interface board 48 (e.g., inputs indicative of properties of the fluid, an operating mode of the compressor 32, and/or an operating mode of the vapor compression system 14 generally).

[0039] After determining the target flow rate, the fluid pressure control system 110 may adjust the flow rate of the fluid to the target flow rate (e.g., adjust the speed of the pump 90 to control the pressure of the fluid along the lubrication circuit 80). For example, the microprocessor 44 may be communicatively coupled to the sump 82 and the pump 90 and may output a signal to the pump 90 indicative of an adjustment to the pump 90 to control the flow rate of the fluid to achieve the target flow rate. In certain embodiments, the microprocessor 44 may provide a user-detectable notification and/or alert via an indicator 132 of the interface board 48 (e.g., a user interface). The indicator 132 may be any user-detectable notification, such as a light emitting diode (LED), an audible alert, a display, text, and/or another suitable notification. For example, the user- detectable notification and/or alert may indicate the flow rate of the fluid, the target flow rate, a difference between the flow rate and the target flow rate, the temperature in the compressor 32 at the bearing 96, a pressure of the fluid along the lubrication circuit 80, or a combination thereof.

[0040] In certain embodiments, the fluid pressure control system 110 may include a sensor 120 configured to provide feedback to the control panel 40 indicative of the flow rate of the fluid at the pump 90 and/or exiting the pump 90 (e.g., a speed of the pump 90 and/or a discharge pressure of the pump 90). As illustrated, the sensor 120 is coupled to the pump 90 and is disposed within the sump 82. In other embodiments, the sensor 120 may be disposed external to the sump 82 and may be configured to provide feedback indicative of the flow rate of the fluid flowing from the pump 90 prior to entering the compressor 32 (e.g., the flow rate along the compressor supply conduit 92 and/or at the compressor fluid inlet 98).

[0041] The microprocessor 44 may compare the flow rate (e.g., the flow rate detected by the sensor 120) to the target flow rate and may control the pump 90 based on the comparison. For example, if a difference between the flow rate and the target flow rate exceeds a threshold difference, the microprocessor 44 may output the signal to the pump 90 to enable adjustment of the flow rate to the target flow rate (e.g., by increasing or decreasing a speed of the pump 90). The threshold difference may be based on a type of the fluid, operating parameters of the fluid, an operating mode of the compressor 32 and/or the vapor compression system 14, operator inputs, or a combination thereof. Additionally or alternatively, the threshold difference may be a percentage difference (e.g., one percent, two percent, five percent, ten percent, etc.) between the flow rate and the target flow rate.

[0042] As illustrated, the fluid pressure control system 110 includes the control panel 40 of the vapor compression system 14 configured to receive feedback indicative of the shaft speed and/or the temperature, determine the target flow rate, and adjust operation of the pump 90 to achieve the target flow rate. Additionally or alternatively, the fluid pressure control system 110 may include an additional controller configured to receive feedback indicative of the shaft speed and/or the temperature, determine the target flow rate, and adjust operation of the pump 90 to achieve the target flow rate. For example, the additional controller may be a controller of the lubrication circuit 80 and may be configured to control the flow of the fluid along the lubrication circuit 80.

[0043] In some embodiments, the memory 46 of the control panel 40 may include one or more tangible, non-transitory, computer-readable media that store instructions executable by the microprocessor 44 and/or data to be processed by the microprocessor 44. For example, the memory 46 may include random access memory (RAM), read-only memory (ROM), rewritable non-volatile memory such as flash memory, hard drives, optical discs, other types of memory, or a combination thereof. Additionally, the microprocessor 44 may include one or more general purpose microprocessors, one or more application specific integrated circuits (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof to execute instructions stored in the memory 46.

[0044] FIG. 7 is a flow chart illustrating an embodiment of a process 140 for operating the fluid pressure control system 110. It is to be understood that the steps discussed herein are merely exemplary, and certain steps may be omitted or performed in a different order than the order described below. In some embodiments, the process 140 may be stored in the memory 46 and executed by the microprocessor 44 of the control panel 40 or stored in other suitable memory and executed by other suitable processing circuitry of the fluid pressure control system 110.

[0045] As shown in the illustrated embodiment of FIG. 7, at block 142, the fluid pressure control system 110, via the microprocessor 44, receives feedback indicative of an operating parameter from a sensor disposed along the lubrication circuit 80 (e.g., the sensors 112, 114, 116, 118, and/or 120). The operating parameters may include the speed of the shaft 94, the temperature in the compressor 32 at the bearing 96, the fluid supply temperature along the compressor supply conduit 92, the fluid drain temperature along the compressor drain conduit 84, the flow rate of the fluid at the pump 90, other operating parameters associated with the operation of the vapor compression system 14 (e.g., operating parameters of the refrigerant), or a combination thereof. As described above, the microprocessor 44 may be configured to determine the temperature in the compressor 32 at the bearing 96 based on the fluid supply temperature and/or the fluid drain temperature.

[0046] At block 144, the fluid pressure control system 110 adjusts the flow rate of the fluid along the lubrication circuit 80 based on the feedback indicative of the operating parameter. For example, the microprocessor 44 may determine the target flow rate of the fluid based on the feedback (e.g., feedback indicative of the speed of the shaft 94, the temperature in the compressor 32 at the bearing 96, the fluid supply temperature along the compressor supply conduit 92, the fluid drain temperature along the compressor drain conduit 84, the flow rate of the fluid at the pump 90, the other operating parameters associated with the operation of the vapor compression system 14, or any combination thereof) and may output the signal to the pump 90 to enable adjustment of the flow rate of the fluid to achieve the target flow rate (e.g., output a signal to adjust a speed of the pump 90). In certain embodiments, the microprocessor 44 may compare the measured or detected flow rate to the target flow rate and, in response to a difference between the flow rate and the target flow rate exceeding a threshold difference, output the signal to the pump 90 to enable adjustment of the flow rate of the fluid.

[0047] In some embodiments, the fluid pressure control system 110 may adjust the flow rate of the fluid along the lubrication circuit 80 based on the speed of the shaft 94 and the temperature in the compressor 32 at the bearing 96. For example, the microprocessor 44 may determine the target flow rate based on a target temperature range in the compressor 32 at the bearing 96. Feedback indicative of an actual temperature in the compressor 32 at the bearing 96 may be received from the sensors 114, 116, and/or 118, may be determined based on feedback from the sensors 114, 116, and/or 1 18, and/or may be received via the inputs 130. When the actual temperature in the compressor 32 at the bearing 96 is outside of the target temperature range, the microprocessor 44 may output a signal to the pump 90 to effectuate an adjustment of the flow rate of the fluid. In some embodiments, the memory 46 may store a range of operating parameters (e.g., a range of speeds) that enables the pump 90 to effectively operate. When the microprocessor 44 determines that the target flow rate of the fluid may cause the pump 90 to operate outside of the range of operating parameters, the microprocessor 44 may instruct the pump 90 to operate at an upper limit value or lower limit value of the range of operating parameters.

[0048] Similarly, the microprocessor 44 may determine the target flow rate of the fluid based on the speed of the shaft 94. For example, the microprocessor 44 may determine the target flow rate as a function (e.g., linear function, proportional function, exponential function) of the shaft speed. In certain embodiments, the microprocessor 44 may compare the measured flow rate to the target flow rate and, in response to a difference between the measured flow rate and the target flow rate exceeding a threshold difference, output the signal to the pump 90 to cause adjustment of the flow rate of the fluid.

[0049] In certain embodiments, if the target flow rate of the fluid would cause the pump 90 to operate outside the range of operating parameters, the microprocessor may perform a check on the feedback from the sensors 114, 116, and/or 118 to determine whether the sensors 114, 116, and/or 118 are performing accurately, whether operation of the pump 90, the compressor 32, or the vapor compression system 14 should be stopped, or whether another control action should be performed. For example, if the feedback from the sensor 114 (e.g., feedback indicative of a temperature of the fluid in the compressor 32 at the bearing 96) corresponds to a first target flow rate outside the range of operating parameters, the microprocessor 44 may determine whether feedback from a second sensor (e.g., the sensor 116 or 118) corresponds to a second target flow rate also outside the range of operating parameters. If both the first and second target flow rates would cause the pump 90 to operate outside the range of operating parameters, the microprocessor 44 may output a control signal to shutdown operation of the pump 90, the compressor 32, and/or the vapor compression system 14 or to perform another control operation. If only one of the first or second target flow rates would cause the pump 90 to operate outside the range of operating parameters, the microprocessor 44 may output a signal to the control panel 40 to provide a status/condition of the sensor 114, 116, and/or 118 (e.g., that the sensor 114, 116, and/or 118 may not be operating properly).

[0050] FIG. 8 is a flow chart illustrating an embodiment of a process 150 for operating the fluid pressure control system 110. It is to be understood that the steps discussed herein are merely exemplary, and certain steps may be omitted or performed in a different order than the order described below. In some embodiments, the process 150 may be stored in the memory 46 and executed by the microprocessor 44 of the control panel 40 or stored in other suitable memory and executed by other suitable processing circuitry.

[0051] As shown in the illustrated embodiment of FIG. 8, at block 152, the fluid pressure control system 110, via the microprocessor 44, receives input(s) indicative of fluid properties (e.g., operating properties of the fluid of the lubrication circuit 80, a type of the fluid, operating properties of other fluids within the vapor compression system 14). For example, the inputs may include the inputs 130 provided to the interface board 48.

[0052] At block 154, the microprocessor 44 receives feedback indicative of the speed of the shaft 94 from the sensor 112. At block 156, the microprocessor 44 determines the target flow rate of the fluid to the bearing 96 based on the speed of the shaft 94. For example, the microprocessor 44 may determine the target flow rate of the fluid as a function of the speed of the shaft 94 (e.g., a linear function, a non-linear function, a proportional function, an exponential function, or a combination thereof) and/or may reference lookup tables to determine the target flow rate based on the speed of the shaft 94.

[0053] At block 158, the fluid pressure control system 110 adjusts operation of the pump 90 (e.g., a speed of the pump 90 and/or a position/angle of a swashplate of the pump 90) to adjust the flow rate of the fluid and to achieve the target flow rate. For example, the fluid pressure control system 110 may determine a target speed of the pump 90 that will achieve the target flow rate, compare the target speed to a range of operating speeds of the pump 90, select an operating speed of the pump 90 from the range of operating speeds based on the target speed, and adjust operation of the pump 90 to the selected operating speed. In certain embodiments, the microprocessor 44 may compare the measured flow rate to the target flow rate and, in response to the difference between the measured flow rate and the target flow rate exceeding a threshold difference, output the signal to the pump 90 to enable adjustment of the flow rate of the fluid.

[0054] FIG. 9 is a flow chart illustrating an embodiment of a process 160 for operating the fluid pressure control system 110. It is to be understood that the steps discussed herein are merely exemplary, and certain steps may be omitted or performed in a different order than the order described below. In some embodiments, the process 160 may be stored in the memory 46 and executed by the microprocessor 44 of the control panel 40 or stored in other suitable memory and executed by other suitable processing circuitry.

[0055] As shown in the illustrated embodiment of FIG. 9, at block 162, the fluid pressure control system 110, via the microprocessor 44, receives input(s) indicative of fluid properties (e.g., operating properties of the fluid of the lubrication circuit 80, a type of the fluid, operating properties of other fluids within the vapor compression system 14). In some embodiments, the feedback may include the inputs 130 provided to the interface board 48 by a user, for example.

[0056] At block 164, the microprocessor 44 receives the feedback, which may include feedback indicative of a temperature of the fluid in the compressor 32 at the bearing 96 from the sensor 114. Additionally or alternatively, the microprocessor 44 may receive the fluid supply temperature from the sensor 116 and/or the fluid drain temperature from the sensor 118 and may determine the temperature of the fluid in the compressor 32 at the bearing 96 based on the fluid supply temperature and/or the fluid drain temperature.

[0057] At block 166, the microprocessor 44 determines the target flow rate of the fluid from the pump 90 to the bearing 96 based on the temperature in the compressor 32 at the bearing 96. For example, the microprocessor 44 may determine the target flow rate of the fluid as a function of the temperature at the bearing 96 (e.g., a linear function, a non- linear function, a proportional function, an exponential function, or a combination thereof) and/or may reference lookup tables to determine the target flow rate based on the temperature at the bearing 96.

[0058] At block 168, the fluid pressure control system 110 adjusts operation of the pump 90 to control the flow rate of the fluid and to achieve the target flow rate. For example, the fluid pressure control system 110 may determine a target speed of the pump 90 that will achieve the target flow rate, compare the target speed to a range of operating speeds of the pump 90, select an operating speed of the pump 90 from the range of operating speeds based on the target speed, and adjust operation of the pump 90 to the selected operating speed. In certain embodiments, the microprocessor 44 may compare the measured flow rate to the target flow rate and, in response to the difference between the measured flow rate and the target flow rate exceeding a threshold difference, output the signal to the pump 90 to enable adjustment of the flow rate of the fluid.

[0059] Although the processes 140, 150, and 160 are described herein as individual processes, the processes 140, 150, and 160, or certain steps thereof, may be combined into a single process or method. For example, the fluid pressure control system 110 may perform steps of the processes 140, 150, and 160 simultaneously or independently. In certain embodiments, as described above, the fluid pressure control system 110 may control the flow rate of the fluid along the lubrication circuit 80 as a function of both the speed of the shaft 94 and the temperature of the fluid in the compressor 32 at the bearing 96.

[0060] Accordingly, the present disclosure is directed to a fluid pressure control system for lubricating various components of a compressor. The fluid pressure control system includes sensors that provide feedback indicative of a speed of a shaft of the compressor and/or a temperature in the compressor at a bearing. For example, a first sensor may be disposed proximate to the shaft and may be configured to provide feedback indicative of the speed of the shaft. A second sensor may be disposed proximate to the bearing and may be configured to provide feedback indicative of the temperature in the compressor at the bearing. In certain embodiments, sensors may be disposed at a compressor supply conduit of the compressor and/or at a compressor drain conduit of the compressor and may be configured to detect a fluid supply temperature and a fluid drain temperature, respectively, of the fluid. As such, a controller of the fluid pressure control system may determine the temperature in the compressor at the bearing based on the fluid supply temperature and/or the fluid drain temperature.

[0061] Further, the controller may adjust operating parameters of a pump to control a flow rate of the fluid from the pump to the bearing based on the speed of the shaft and/or the temperature in the compressor at the bearing. For example, the controller may determine a target flow rate based on the speed of the shaft and/or the temperature at the bearing and may adjust the pump to achieve the target flow. In some embodiments, the target flow rate may be a function of the speed of the shaft and/or the temperature at the bearing (e.g., a linear function, a non-linear function, a proportional function, an exponential function, or a combination thereof). As the speed of the shaft and/or the temperature at the bearing decreases, the controller may generally adjust operation of the pump to reduce the flow rate. As the speed of the shaft and/or the temperature at the bearing increases, the controller may generally adjust operation of the pump to increase the flow rate. In any case, the controller adjusts operation of the pump to control the flow rate of the fluid, which may improve operation and efficiency of the compressor and/or the vapor compression system generally. For example, controlling the flow rate may at least partially block or reduce leakage of the fluid at seals of the compressor and/or may reduce friction between the fluid, the shaft, and/or the bearing.

[0062] While only certain features and embodiments of the invention have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the claimed invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.