Pumps for HVAC&R systems

Abstract

A pump (206) for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system (10) includes a pump body (302) defining a compression chamber (316). The HVAC&R system (10) also includes a piston housing (311) coupled to the pump body (302). The piston housing (311) includes a piston cavity (328). The pump (206) further includes a piston (306) disposed within the piston housing (311). The piston (306) includes a plunger section (318) configured to reciprocate between the compression chamber (316) and the piston cavity (328). Additionally, the piston (306) includes a head section (332) configured to reciprocate within the piston cavity (328). The pump (206) further includes a solenoid coil (312) configured to induce a magnetic force on the piston (306). The pump (206) further includes a controller (314) configured to control the flow of current through the solenoid coil (312) to control the reciprocating motion of the piston (306) within the piston cavity (328).

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 541,201, entitled "PUMP FOR HVAC&R SYSTEM," filed September 28, 2023, and U.S. Provisional Application No. 63 / 443,921, entitled "BEARING SYSTEM FOR HVAC&R SYSTEM," filed February 7, 2023, each of which is incorporated herein by reference in its entirety for all purposes. [Background technology]

[0002]

[0003] This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present disclosure, as 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] Chiller systems, or vapor compression systems, utilize a working fluid (e.g., refrigerant, etc.) that changes phase between vapor, liquid, and mixtures thereof in response to exposure to different temperatures and pressures within the chiller system components. The chiller system may place the working fluid in a heat exchange relationship with a conditioned fluid (e.g., water) and deliver the conditioned fluid to conditioning equipment provided by the chiller system and / or the environment being conditioned. In such applications, the conditioned fluid may be routed through downstream equipment, such as an air handler, to condition other fluids, such as building air. The chiller system may include a compressor configured to pressurize the working fluid and circulate it through the chiller system's working fluid circuit. In some applications, the compressor's shaft may be rotatably driven by a motor to drive rotation of the compressor's impeller, which pressurizes the working fluid. Traditionally, compressors include bearings configured to facilitate shaft rotation. Unfortunately, existing bearings utilized with compressors can be complex and expensive and / or contribute to inefficiencies in the operation of the chiller system. Summary of the Invention

[0004] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these particular embodiments, and that these aspects are not intended to limit the scope of the disclosure. Indeed, the disclosure may encompass a variety of aspects that may not be set forth below.

[0005] In one embodiment, a pump for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a pump body defining a compression chamber. The HVAC&R system also includes a piston housing coupled to the pump body. The piston housing includes a piston cavity. The pump further includes a piston disposed within the piston housing. The piston includes a plunger section configured to reciprocate between the compression chamber and the piston cavity. Additionally, the piston includes a head section configured to reciprocate within the piston cavity. The pump further includes a solenoid coil configured to induce a magnetic force on the piston. The pump further includes a controller configured to control a flow of current through the solenoid coil to control the reciprocating movement of the piston within the piston cavity.

[0006] In another embodiment, a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system includes a pump configured to pump fluid along a circuit of the HVAC&R system. The pump includes a piston configured to reciprocate within a piston chamber of a piston housing. Additionally, the pump includes a bump stop disposed at an end of the piston chamber. The bump stop includes an internal switch configured to detect contact between the bump stop and the piston. The HVAC&R system also includes a controller configured to control a stroke rate of the piston based on a signal received from the internal switch.

[0007] In another embodiment, a method of operating a pump includes energizing a solenoid coil to translate a piston in a first direction within a piston cavity. The method also includes detecting a first contact between the piston and a first bump stop within the piston cavity. The method further includes energizing the solenoid coil to translate the piston in a second direction within the piston cavity opposite the first direction. Additionally, the method includes detecting a second contact between the piston and a second bump stop within the piston cavity. The method further includes determining a time interval between the first contact and the second contact. The method further includes adjusting energization of the solenoid coil based on a difference between the time interval and a previous time interval.

[0008] The various aspects of the present disclosure may be better understood by reading the following detailed description and by reviewing the drawings, in which: [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of an embodiment of a building that may utilize a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system in a commercial environment, according to an aspect of the present disclosure. [Figure 2] FIG. 1 is a perspective view of an embodiment of a vapor compression system according to an aspect of the present disclosure. [Figure 3] 1 is a schematic diagram of an embodiment of a vapor compression system according to an aspect of the present disclosure. [Figure 4] 1 is a schematic diagram of an embodiment of a vapor compression system according to an aspect of the present disclosure. [Figure 5] FIG. 1 is a cross-sectional side view of an embodiment of a compressor of a vapor compression system illustrating a bearing system of the compressor according to one aspect of the present disclosure. [Figure 6] 1 is a schematic diagram of an embodiment of a vapor compression system including a bearing system for a compressor, according to an aspect of the present disclosure. [Figure 7] FIG. 1 is a cross-sectional side view of an embodiment of a pump for a fluid supply system of a bearing system, according to an aspect of the present disclosure. [Figure 8]1 is a schematic cross-sectional side view of an embodiment of a portion of a pump of a fluid supply system of a bearing system, in accordance with an aspect of the present disclosure; [Figure 9] 1 is a schematic cross-sectional side view of an embodiment of a portion of a pump of a fluid supply system of a bearing system, in accordance with an aspect of the present disclosure; [Figure 10] 1 is a flow chart of an embodiment of a method for operating a pump for a fluid supply system of a bearing system, according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] One or more specific embodiments are described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described herein. It should be understood that the development of any such actual implementation, as with any engineering or design project, will require numerous implementation-specific decisions to be made to achieve the developers' particular goals, including compliance with system- and business-related constraints that may vary from implementation to implementation. It should further be understood 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 in the art having the benefit of this disclosure.

[0011] When introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "the" are intended to mean that there are one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to "one embodiment" or "embodiments" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0012] As used herein, terms such as "approximately," "generally," and "substantially" are intended to convey, as one of ordinary skill in the art would understand, that a stated property value can be within a relatively small range of the property value. For example, when an attribute value is described as being "approximately" equal to (or, e.g., "substantially similar to") a given value, this is intended to mean that the attribute value can be within + / -5%, + / -4%, + / -3%, + / -2%, + / -1% of the given value, or even close to it. Similarly, when a given feature is described as being "substantially parallel" to another feature, "generally perpendicular" to another feature, etc., this is intended to mean that the given feature is within + / -5%, + / -4%, + / -3%, + / -2%, + / -1%, or even close to having the stated property, such as being parallel to another feature or perpendicular to another feature. Furthermore, it should be understood that mathematical terms such as "planar," "inclined," "vertical," "parallel," etc. are intended to encompass characteristics of surfaces or elements as understood by one of ordinary skill in the relevant art, and should not be interpreted strictly as they may be understood in the mathematical arts. For example, a "planar" surface is intended to encompass a surface that is machined, molded, or otherwise formed to be substantially flat or smooth (within relevant tolerances) using techniques and tools available to one of ordinary skill in the art. Similarly, a surface having an "inclined" is intended to encompass a surface that is machined, molded, or otherwise formed to be oriented at an angle (e.g., tilted) relative to a reference point using techniques and tools available to one of ordinary skill in the art.

[0013] Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system (e.g., a chiller) that includes a vapor compression system (e.g., a vapor compression circuit, a working fluid circuit) having a compressor. During operation, the compressor pressurizes a working fluid in the vapor compression system and directs the working fluid to a condenser (e.g., a first heat exchanger), which may cool and condense the working fluid. The condensed working fluid may be directed to an expansion device that may reduce the pressure of the working fluid and further cool the working fluid. From the expansion device, the cooled working fluid may be directed to an evaporator (e.g., a second heat exchanger), where the working fluid is placed in a heat exchange relationship with a conditioned fluid and may cool the conditioned fluid. The conditioned fluid may be circulated between the evaporator and a structure, such as a building, and the conditioned fluid is used to cool an airflow delivered to a conditioned space of the structure. In some embodiments, an air handling unit (AHU) of the HVAC&R system may receive the conditioned fluid from the chiller and utilize the conditioned fluid to cool the airflow delivered to the conditioned space. The conditioning fluid can then be returned to the evaporator and cooled again.

[0014] In some embodiments, the compressor may include a bearing system including bearings (e.g., hydrostatic bearings, porous bearings) that utilize pressurized fluid to support and lubricate the compressor's rotating shaft. According to the present technology, the bearings may be configured to receive pressurized fluid (e.g., liquid phase) and expel pressurized fluid (e.g., gas phase) toward the rotating shaft to enable the levitation and rotation of the rotating shape. For example, the bearing system may include a lubricant circuit extending from a working fluid circuit of a vapor compression system, directing a portion of the working fluid from the working fluid circuit to the compressor's bearings. That is, a portion of the working fluid (e.g., refrigerant) in the lubricant circuit may be utilized as a lubricating fluid. The lubricant circuit may include a pump configured to pump the pressurized fluid (e.g., lubricating fluid) toward the compressor's bearings. In this manner, the working fluid configured to exchange heat with the conditioning fluid as part of the working fluid circuit may be utilized in conjunction with the bearings to enable the bearings to support the compressor's shaft. The pump may be a linear piston pump configured to apply pressure to the working fluid through the reciprocating motion of a piston. Unfortunately, existing pumps can generate localized low-pressure areas that can cause cavitation of the working fluid within the pump. Such cavitation can cause undesirable inefficiency, wear, and / or deterioration in the pump. Cavitation can be particularly concerning during dead-head operation of the pump. In certain situations, the pump may operate without working fluid flow therethrough (e.g., due to closed valves and / or other blockages in the lubricant circuit). In the absence of working fluid flow through the pump (e.g., a dead-head condition), pressurization of a constant mass of working fluid within the pump can increase the temperature of the working fluid, resulting in cavitation during the piston return stroke. Furthermore, the increased temperature can cause undesirable wear and / or deterioration in pump components.

[0015] Accordingly, the present embodiments relate to an improved pump configured to pump a working fluid to a compressor bearing, including a system and method for operating the pump. In particular, the pump is configured to maintain operation through a variety of operating conditions, including deadhead, while reducing cavitation of the working fluid. The pump includes a piston that may be driven (e.g., in a reciprocating motion) by a solenoid coil controlled by a pump controller. The pump controller may control current supplied to the solenoid coil to control the direction and velocity of the piston, such as by following a current profile. Additionally, the pump controller may adjust the current profile to reduce the speed of the piston's return stroke in response to detections indicating cavitation and / or potential cavitation.

[0016] To this end, the pump may include a forward bump stop (e.g., a first bump stop, a travel stop, a damping stop) and a return bump stop (e.g., a second bump stop, a travel stop, a damping stop), each positioned at a respective end of the pump's piston chamber in which the piston is disposed. Each bump stop is configured to mechanically stop the piston upon impact at a respective end of the piston chamber (e.g., top dead center, bottom dead center). Each bump stop may also include an internal switch mechanism configured to send a signal to the pump controller indicative of contact between the bump stop and the piston. Based on the detected time interval between receipt of signals from the bump stops, the pump controller may determine the speed and / or time (e.g., length of time) of the compression stroke of the piston. Based on determining that the speed and / or time of the compression stroke appears abnormal and / or is abnormal (e.g., slower than the previous compression stroke), the pump controller may determine that cavitation is likely occurring on the return stroke of the piston. In response to determining that the speed of the compression stroke is slower than the previous compression stroke by a threshold amount and / or that the duration of the compression stroke is longer than the previous compression stroke, the pump controller may adjust the current profile to decrease the speed of the piston during the return stroke and / or increase the duration of the return stroke. In this manner, the occurrence of localized low-pressure regions in the wake of the piston on the return stroke may be reduced and / or mitigated, thereby reducing cavitation. Additionally, the pump may include a non-magnetic heat sink coupled to the piston to facilitate cooling of the pump during operation. Thus, the pump is configured to operate under a variety of operating conditions while resisting the harmful effects of dead head experienced by conventional pumps.

[0017] Referring now to the drawings, FIG. 1 is a perspective view of one embodiment of a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system 10 within a building 12 for a typical commercial environment. The HVAC&R system may include a vapor compression system 14 that provides cold liquid for cooling the building 12 and a boiler 16 that provides warm liquid for heating the building 12. The vapor compression system 14, also referred to herein as a chiller, may circulate a working fluid (e.g., a refrigerant) that is cooled by a cooling fluid (e.g., a liquid such as water) in a condenser of the vapor compression system 14 and heated by a conditioning fluid (e.g., a liquid such as water) in an evaporator of the vapor compression system 14. The cooling fluid may be provided, for example, by a cooling tower that cools the cooling fluid via ambient air. The conditioning fluid, cooled by the working fluid as described above, may be utilized to cool an airflow provided to a conditioned space of the building 12.

[0018] HVAC&R system 10 may also include an air distribution system that circulates air through building 12. The air distribution system may also include air return ducts 18, air supply ducts 20, and / or air handlers 22. In some embodiments, air handlers 22 may include a heat exchanger connected to boiler 16 and vapor compression system 14 by conduits 24. The heat exchanger within air handler 22 may receive either a warm liquid from boiler 16 or a conditioned fluid (e.g., a cold liquid such as water) from vapor compression system 14, depending on the operating mode of HVAC&R system 10. Although HVAC&R system 10 is shown with a separate air handler for each floor of building 12, in other embodiments, HVAC&R system 10 may include air handlers 22 and / or other components that may be shared between floors.

[0019] 2 and 3 illustrate an embodiment of a vapor compression system 14 or chiller that can be used in HVAC&R system 10. Vapor compression system 14 may circulate a working fluid through a circuit (e.g., a working fluid circuit) that begins with a compressor 32, such as a centrifugal compressor. The circuit may also include a condenser 34, expansion valve(s) or device(s) 36, and an evaporator 38. Vapor compression system 14 may further include a control panel 40 having an analog-to-digital (A / D) converter 42, a microprocessor 44, non-volatile memory 46, and / or an interface board 48.

[0020] Some examples of fluids that can be used as working fluids in vapor compression system 14 include hydrofluorocarbon (HFC) refrigerants, such as R-410A, R-407, R-134a, hydrofluoroolefins (HFOs), ammonia (NH), R-717, carbon dioxide (CO), R-744, or "natural" refrigerants such as hydrocarbon-based refrigerants, water vapor, or any other suitable refrigerant. Other possible working fluids include R-123, R-514A, R-1130yd, R-1233zd, R-134a, R-1142ze, R-1142yf, R-1311, R-32, and R-410A. In some embodiments, vapor compression system 14 can be configured to efficiently utilize working fluids with a normal boiling point of approximately 19 degrees Celsius (66 degrees Fahrenheit) at 1 atmosphere, also referred to as low-pressure refrigerants, compared to medium-pressure working fluids such as R-134a. As used herein, "normal boiling point" may refer to the boiling point temperature measured at one atmosphere pressure.

[0021] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSD) 52, a motor 50, a compressor 32, a condenser 34, an expansion valve or device 36, and / or an evaporator 38. The motor 50 may drive the compressor 32 during normal operation and may be powered by the variable speed drive (VSD) 52. The VSD 52 receives alternating current (AC) power during normal operation, where the AC power includes a particular constant line voltage and constant 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.

[0022] The compressor 32 compresses a working fluid 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 working fluid 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 working fluid vapor may condense into a working fluid liquid in the condenser 34 as a result of the heat transfer with the cooling fluid. The liquid working fluid from the condenser 34 may flow through an expansion device 36 to an 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 that supplies cooling fluid to the condenser 34.

[0023] The liquid working fluid delivered to the evaporator 38 may absorb heat from a conditioning fluid that is then sent to a load 62 (e.g., the building 12 of FIG. 1 ). For example, the conditioning fluid may be cooled by the working fluid in the evaporator 38 and then utilized in the building 12 of FIG. 1 to condition the airflow provided to condition the space within the building 12. The liquid working fluid in the evaporator 38 may undergo a phase change from a liquid working fluid to a working fluid 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 the cooling load 62. The conditioning 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 the return line 60R and exits the evaporator 38 via the supply line 60S. The evaporator 38 may reduce the temperature of the conditioning fluid in the tube bundle 58 through heat transfer with the working fluid. The tube bundle 58 in the evaporator 38 may include multiple tubes and / or multiple tube bundles. In either case, the vapor working fluid exits the evaporator 38 and returns to the compressor 32 via a suction line to complete the cycle.

[0024] FIG. 4 is a schematic diagram of an embodiment of the vapor compression system 14 having an intermediate circuit 64 incorporated between the condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 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 reduce the pressure of (e.g., expand) the liquid working fluid received from the condenser 34. During the expansion process, a portion of the liquid working fluid may evaporate; therefore, the intermediate vessel 70 may be used to separate the vapor working fluid and the liquid working fluid received from the first expansion device 66. Additionally, intermediate vessel 70 may provide further expansion of the liquid working fluid due to the drop in pressure the liquid working fluid experiences as it enters intermediate vessel 70 (e.g., due to the sudden increase in volume it experiences as it enters intermediate vessel 70). The vapor working fluid in intermediate vessel 70 may be drawn by compressor 32 through a suction line 74 of compressor 32. In other embodiments, the vapor working fluid in intermediate vessel 70 may be drawn into an intermediate stage (e.g., rather than the suction stage) of compressor 32. The liquid working fluid collecting in intermediate vessel 70 may be at a lower enthalpy than the liquid working fluid exiting condenser 34 due to the expansion of the working fluid in expansion device 66 and / or intermediate vessel 70. The liquid working fluid from intermediate vessel 70 may then flow through line 72 and through second expansion device 36 to evaporator 38.

[0025] According to this embodiment, the compressor 32 may be a centrifugal compressor (e.g., a hermetic compressor) having a floating rotor or shaft. To this end, the vapor compression system 14 includes a bearing system with one or more bearings configured to support the load of the shaft of the compressor 32. The bearing system is configured to direct a pressurized fluid (e.g., a liquid, working fluid, refrigerant) through the bearing, which is configured to discharge the fluid toward and away from the shaft to enable the shaft to float within the compressor 32. Specifically, the bearing includes one or more porous bearing elements configured to receive and direct the pressurized fluid toward the shaft within the housing of the compressor 32. In this manner, the bearing system may support the load on the shaft and enable the shaft to rotate within the housing of the compressor 32 during operation of the vapor compression system 14. As discussed herein, the pressurized fluid may be a portion of the working fluid (e.g., a refrigerant) circulating through the vapor compression system 14. Accordingly, the vapor compression system 14 may not utilize a dedicated lubricant, such as oil, to support and enable rotation of the shaft of the compressor 32. Furthermore, the bearing system may incorporate the vapor compression system 14 at a reduced cost compared to other existing bearing system designs. The disclosed embodiments also allow for improved (e.g., simplified) control of the bearing system as well as more efficient operation of the vapor compression system 14.

[0026] With the above in mind, FIG. 5 is a side cross-sectional view of one embodiment of a compressor 32 including a bearing system 100 in accordance with aspects of the present disclosure. The compressor 32 may include a housing 102 and a shaft 104 extending through the housing 102. The compressor 32 may also include an impeller 106 coupled to the shaft 104, such as via a fastener 108. During operation of the compressor 32, the shaft 104 may rotate (e.g., via operation of the motor 50), causing the impeller 106 to rotate. The rotation of the impeller 106 may drive a working fluid (e.g., a refrigerant) to flow through a working fluid flow path 110 (e.g., from the evaporator 38, from the intermediate vessel 70, or in a working fluid circuit), drawing the working fluid into the housing 102 toward the impeller 106 via a suction inlet 112. The impeller 106 may impart mechanical energy to the working fluid and discharge the working fluid into a diffuser passage 114 of the compressor 32. The working fluid may be channeled from the diffuser passage 114 to a volute 116 of the compressor 32 and from the volute 116 to a condenser (eg, condenser 34) for heat exchange with a fluid, such as a cooling fluid.

[0027] In the illustrated embodiment, compressor 32 (e.g., bearing system 100) includes a first bearing 118 (e.g., a radial bearing, a bearing assembly, a porous bearing) and a second bearing 120 (e.g., a radial bearing, a bearing assembly, a porous bearing) configured to control and / or adjust the position (e.g., radial position) of shaft 104 relative to an axis 122 (e.g., a rotational axis, a central axis) of shaft 104. For example, first bearing 118 and second bearing 120 may be configured to support a load of shaft 104 such that shaft 104 floats within first bearing 118 and second bearing 120. First bearing 118 and second bearing 120 may also be configured to prevent shaft 104 from moving laterally (e.g., bending, moving radially, rotating eccentrically) relative to axis 122. Compressor 32 (e.g., bearing system 100) further includes a third bearing 124 (e.g., a thrust bearing, an axial bearing, a bearing assembly, a porous bearing) configured to control and / or adjust the position (e.g., axial position) of shaft 104 along axis 122. For example, third bearing 124 may be configured to prevent or limit movement (e.g., translation) of shaft 104 along axis 122.

[0028] As described above, bearing system 100 is configured to direct pressurized fluid to bearings of bearing system 100, such as first bearing 118, second bearing 120, and / or third bearing 124. The pressurized fluid may be the same working fluid (e.g., refrigerant) circulating through vapor compression system 14 having compressor 32. However, it should be appreciated that the pressurized fluid may be any suitable fluid, such as a refrigerant, a condensable vapor, or other fluid. In some embodiments, first bearing 118, second bearing 120, and / or third bearing 124 each include one or more porous elements 126 configured to direct pressurized fluid therethrough. For example, one or more porous elements 126 of first bearing 118 and second bearing 120 may be configured to receive and direct pressurized fluid toward shaft 104 to establish a high-pressure fluid film (e.g., a vapor film) around shaft 104 between first bearing 118, second bearing 120, and shaft 104. In this manner, the pressurized fluid may lift the shaft 104 off the first bearing 118 and the second bearing 120, thereby enabling desired rotation of the shaft 104 about the axis 122. One or more porous elements 126 of the third bearing 124 may receive the pressurized fluid and direct the pressurized fluid toward a collar 128 (e.g., a thrust collar) of the third bearing 124. In this manner, the pressurized fluid may apply a force to the collar 128 to enable adjustable positioning of the shaft 104 along the axis 122.

[0029] The bearing system 100 includes a fluid supply system 130 configured to supply pressurized fluid to the bearings (first bearing 118, second bearing 120, and / or third bearing 124) of the bearing system 100. For example, the fluid supply system 130 may direct the pressurized fluid through the housing 102 of the compressor 32 to one or more bearing housings 132 (e.g., casings) of the first bearing 118, second bearing 120, and third bearing 124. In the illustrated embodiment, one bearing housing 132 is associated with the first bearing 118 and another bearing housing 132 is associated with the second bearing 120. An additional bearing housing 132 may be utilized for the third bearing 124. In other embodiments, the second bearing 120 and the third bearing 124 may be packaged together within a common bearing housing 132. Pressurized fluid may be directed through the bearing housings 132 to the corresponding porous elements 126 held within each bearing housing 132. The fluid supply system 130 is described in further detail below. It should be appreciated that the compressor 32 may include any suitable number or type (e.g., radial bearings, axial bearings) of bearings incorporating the present technology, and the bearings may be positioned in any suitable location within the housing 102 of the compressor 32.

[0030] FIG. 9 is a schematic diagram of one embodiment of a vapor compression system 14 (e.g., an HVAC&R system) including a bearing system 100 for a compressor 32. The vapor compression system 14 includes similar elements as discussed above, including a compressor 32, a motor 50, a condenser 34, and an evaporator 38 (e.g., a falling film evaporator) arranged along a working fluid circuit 200 (e.g., a refrigerant circuit). In accordance with the present technique, the bearing system 100 also includes a fluid supply system 130 configured to direct pressurized fluid to a bearing (e.g., a first bearing 118) of the bearing system 100. In particular, the fluid supply system 130 is configured to direct a portion of the working fluid (e.g., refrigerant) circulated through the working fluid circuit 200 to the bearing assembly 150. To this end, the fluid supply system 130 includes a lubricant circuit 202 (e.g., a fluid supply circuit) extending from the working fluid circuit 200 to the bearing assembly 150 via a fluid conduit 203.

[0031] In the illustrated embodiment, lubricant circuit 202 extends from a liquid line portion 204 of working fluid circuit 200 to one or more of bearing assemblies 150. Liquid line portion 204 extends from condenser 34 to evaporator 38. Thus, the working fluid in liquid line portion 204 may be in a liquid phase. Various components are disposed along lubricant circuit 202 and configured to enable a desired supply of working fluid to bearing assemblies 150 to enable bearing assemblies 150 to support the load of shaft 104 of compressor 32. For example, fluid supply system 130 includes a pump 206 (e.g., a liquid pump) disposed along lubricant circuit 202 and configured to direct a flow of working fluid (e.g., liquid working fluid) along lubricant circuit 202 from liquid line portion 204 of working fluid circuit 200 to bearing assemblies 150 of motor 50 (e.g., compressor 32). The pump 206 may be a linear piston pump in some embodiments, and the pump 206 may be driven via a solenoid coil, a motor, and / or another suitable technique. In some embodiments, the pump 206 may operate without the use of oil or other dedicated lubricants.

[0032] The fluid supply system 130 also includes a pressure accumulator 208 fluidly coupled to the lubricant circuit 202. The pressure accumulator 208 is fluidly coupled to the lubricant circuit 202 downstream of the pump 206 with respect to the flow of working fluid along the lubricant circuit 202. Thus, the pressure accumulator 208 may receive a pressurized flow of working fluid (e.g., liquid working fluid, vapor working fluid, or both) from the pump 206 and the lubricant circuit 202. As will be appreciated, the pressure accumulator 208 is configured to store the pressurized working fluid therein. For example, the pressure accumulator 208 may include a container 210 and a separator 212 (e.g., a bladder, a diaphragm, a piston, etc.) disposed therein. In some embodiments, the separator 212 may divide the interior volume of the vessel 210 into a biasing chamber 214 (e.g., a gas chamber) on a first side of the separator 212 and a fluid chamber 216 (e.g., a liquid chamber, a working fluid chamber) on a second side of the separator 212. The fluid chamber 216 of the pressure accumulator 208 is configured to receive pressurized working fluid from the lubricant circuit 202. The separator 212 may be a bladder or other flexible vessel pre-loaded with a gas (e.g., nitrogen) to enable maintaining the pressure of the working fluid in the fluid chamber 216. In other embodiments, the biasing chamber 214 may be pre-loaded with a gas. In still further embodiments, the biasing chamber 214 may instead include a spring or other mechanical biasing component. In either case, pressure accumulator 208 may operate as a mechanical battery configured to enable the supply (e.g., temporary supply) of pressurized working fluid from fluid chamber 216 to bearing assembly 150 via lubricant circuit 202, such as during periods of non-operation of pump 206. For example, during an interruption in operation of pump 206, pressure accumulator 208 may discharge pressurized working fluid into lubricant circuit 202 for supply to bearing assembly 150. In this manner, bearing assembly 150 may continue to operate to support a load on shaft 104 while operation of pump 206 is resumed and / or operation of compressor 32 (e.g., motor 50) is paused in a controlled manner.In some embodiments, pressure accumulator 208 may also operate to dampen oscillations in the flow of compressed working fluid directed to bearing assembly 150. Additionally, pressure accumulator 208 may be configured to supply compressed working fluid to bearing assembly 150 upon start-up of vapor compression system 14 (e.g., prior to operation of pump 206 and / or compressor 32).

[0033] Fluid supply system 130 may also include other components disposed along lubricant circuit 202, such as a check valve 218 disposed between pump 206 and pressure accumulator 208. Check valve 218 may be configured to close and interrupt the flow of liquid working fluid from pump 206 along the way toward bearing assembly 150 based on the pressure of the liquid working fluid discharged by pump 206. For example, check valve 218 may close in response to the pressure of the liquid working fluid dropping below a threshold value (e.g., a threshold corresponding to a desired liquid working fluid pressure to supply to bearing assembly 150). In such a case, pressurized liquid working fluid stored within pressure accumulator 208 may be supplied to bearing assembly 150 (e.g., with closed check valve 218 interrupting the flow of working fluid back to pump 206) to enable at least temporary continuous operation of bearing assembly 150 to support shaft 104. Check valve 218 may be a ball check valve, a diaphragm check valve, a swing check valve, a stop check valve, a lift check valve, an in-line check valve, or any other suitable valve.

[0034] In some embodiments, fluid supply system 130 may include a filter 220 positioned along lubricant circuit 202 (e.g., downstream of pressure accumulator 208 and upstream of bearing assembly 150). Filter 220 may be configured to remove particulates and / or moisture (e.g., water, water vapor) from the liquid working fluid, for example, before the liquid working fluid is directed to bearing assembly 150.

[0035] Fluid supply system 130 may also include a heat exchanger 222 disposed along lubricant circuit 202. Heat exchanger 222 is disposed upstream of pump 206 with respect to the flow of working fluid through lubricant circuit 202. In some embodiments, heat exchanger 222 may be a brazed plate heat exchanger. During operation, heat exchanger 222 may function as a subcooler configured to subcool working fluid channeled into lubricant circuit 202 from liquid line portion 204. In this manner, heat exchanger 222 may operate to ensure that the working fluid supplied to pump 206 is in a liquid phase, thereby reducing undesirable effects such as flashing of the working fluid in pump 206 and cavitation of pump 206. Heat exchanger 222 is configured to place the working fluid drawn from liquid line portion 204 in a heat exchange relationship with a cooling fluid (e.g., an auxiliary cooling fluid) channeled to heat exchanger 222 via cooling fluid circuit 224. In some embodiments, the cooling fluid may be water. In such embodiments, cooling fluid circuit 224 may be configured to supply cooling fluid from an external source. Additionally or alternatively, cooling fluid circuit 224 may be configured to supply water or other cooling fluid (e.g., cooled via evaporator 38) from conditioned fluid conduits such as supply line 60S and / or return line 60R described above. In some embodiments, the cooling fluid may be another portion of the working fluid from working fluid circuit 200. In such embodiments, cooling fluid circuit 224 may extend from working fluid circuit 200 (e.g., liquid line portion 204) to heat exchanger 222. However, it should be understood that cooling fluid circuit 224 may be configured to direct any suitable cooling fluid to heat exchanger 222 to enable cooling (e.g., sub-cooling) of a portion of the working fluid directed along lubricant circuit 202 toward bearing assembly 150 of compressor 32.

[0036] As described above, bearing assemblies 150 are configured to receive pressurized fluid (e.g., working fluid, refrigerant) and discharge the fluid toward shaft 104 or collar 128. In particular, bearing assemblies 150 each include one or more porous elements configured to channel pressurized working fluid therethrough, flash the pressurized working fluid, and discharge the pressurized vapor working fluid toward shaft 104 or collar 128. The working fluid may then flow through housing 102 of compressor 32 (e.g., motor 50) to one or more drain lines 226 of bearing system 100. For example, bearing system 100 may include a first drain line 228 extending from housing 102 to liquid line portion 204 of working fluid circuit 200. First drain line 228 may include a valve 230 (e.g., an electronic expansion valve) and / or be configured to channel the vapor working fluid from housing 102 to liquid line portion 204 of working fluid circuit 200. Additionally or alternatively, the bearing system 100 may include a second drain line 232 extending from the housing 102 to the evaporator 38 and / or a third drain line 234 extending from the housing 102 to the evaporator 38. In some embodiments, the second drain line 232 is configured to conduct the vapor working fluid from the housing 102 to the evaporator 38, and the third drain line 234 is configured to conduct the liquid working fluid from the housing 102 to the evaporator 38.

[0037] The vapor compression system 14 may also include a controller 250 (e.g., a control system, control board, control panel) communicatively coupled to one or more components of the vapor compression system 14 and / or bearing system 100. The controller 250 is configured to monitor, regulate, and / or otherwise control the operation of the components of the vapor compression system 14 and / or bearing system 100. For example, one or more control transmission devices, such as wires, cables, wireless communication devices, etc., may communicatively couple the compressor 32, the motor 50, the pump 206, and / or other components described herein. Such components may include network interfaces that enable the components of the vapor compression system 14 and / or bearing system 100 to communicate via various protocols, such as Ethernet / IP, ControlNet, DeviceNet, or any other communication network protocol. Alternatively, the communication components may enable the components of the vapor compression system 14 and / or bearing system 100 to communicate via mobile communication technology, Bluetooth, near-field communication technology, etc.

[0038] In some embodiments, controller 250 may comprise part or all of control panel 40 or may be another suitable controller included in vapor compression system 14 and / or bearing system 100. In either case, controller 250 may be configured to control components of vapor compression system 14 and / or bearing system 100 according to the techniques discussed herein. Controller 250 includes processing circuitry 252, such as one or more microprocessors, which may execute software for controlling the components of vapor compression system 14 and / or bearing system 100. Processing circuitry 252 may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and / or one or more application-specific integrated circuits (ASICs), or some combination thereof. For example, processing circuitry 252 may include one or more reduced instruction set (RISC) processors.

[0039] Controller 250 may also include a memory device 254 (e.g., memory) that may store information such as, for example, instructions, control software, look-up tables, configuration data, and the like. Memory device 254 may include volatile memory such as random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM). Memory device 254 may store a variety of information and may be used for a variety of purposes. For example, memory device 254 may store processor-executable instructions, including firmware or software, for execution by processing circuit 252, such as instructions for controlling components of vapor compression system 14 and / or bearing system 100. In some embodiments, memory device 254 is a tangible, non-transitory, machine-readable medium that may store machine-readable instructions for execution by processing circuit 252. Memory device 254 may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. Memory device 254 may store data, instructions, and any other suitable data. It should be understood that the memory device 254 may store processor-executable instructions (e.g., for execution via the processing circuitry 252) to enable operation of any of the components described herein and to enable any of the functions and / or operations described herein.

[0040] Controller 250 may be configured to control operation of components of vapor compression system 14 and / or bearing system 100 based on detected operating parameters of vapor compression system 14 and / or bearing system 100. To this end, vapor compression system 14 includes one or more sensors 256 configured to detect operating parameters related to or indicative of the operating state of vapor compression system 14 and bearing system 100. For example, one or more of sensors 256 may be disposed along lubricant circuit 202 and configured to detect operating parameters such as the temperature, pressure, flow rate, etc. of the working fluid channeled through lubricant circuit 202. In some embodiments, one or more sensors 256 may be configured to detect operating parameters related to motor 50, such as the rotational speed of shaft 104, the torque on shaft 104, the temperature of motor 50, etc. One or more sensors 256 may also be configured to detect operating parameters of bearing assembly 150, such as detecting whether one or more bearing assemblies 150 are in contact (e.g., physical contact) with shaft 104, as described further below.

[0041] In some embodiments, one of sensors 256 may be configured to detect an operating parameter associated with pressure accumulator 208, such as the pressure of the working fluid in fluid chamber 216 and / or the pressure of the gas in bias chamber 214. Additionally or alternatively, one or more of sensors 256 may be configured to detect the level of the working fluid in condenser 34, which may be referenced prior to and / or during start-up of bearing system 100 and / or vapor compression system 14. As will be appreciated, each sensor 256 included in vapor compression system 14 may be communicatively coupled to controller 250. Thus, controller 250 may receive data and / or feedback from sensor 256 and may control the operation of vapor compression system 14 and / or bearing system 100 based on the feedback and / or data.

[0042] 7 is a cross-sectional side view of one embodiment of a pump 206 according to aspects of the present disclosure. As discussed above, the pump 206 is configured to pump hydraulic fluid along the lubricant circuit 202 toward the bearing assembly 150. The pump 206 includes an inlet 300 (e.g., an inlet port) configured to receive a flow of hydraulic fluid into a pump body 302 (e.g., a pump housing) and an outlet 304 (e.g., an exhaust port, an outlet valve) configured to exhaust the hydraulic fluid from the pump body 302 and direct the hydraulic fluid toward the bearing assembly 150. Additionally, the pump 206 may include a piston 306 (e.g., an intensifier piston) at least partially disposed within the pump body 302. The piston 306 is configured to move back and forth (e.g., reciprocate) within the pump body 302 to pressurize the hydraulic fluid. That is, the piston 306 may undergo a reciprocating motion that includes a compression stroke in a forward direction 308 and a return stroke in a return direction 310. During the return stroke, the piston 306 may draw working fluid into the pump body 302 through the inlet 300. The piston 306 may then reverse direction to perform a compression stroke, pressurizing the working fluid and expelling it from the pump body 302 through the outlet 304.

[0043] Pump body 302 may be coupled (e.g., removably coupled) to piston housing 311. Movement of piston 306 may be driven by a solenoid coil 312 disposed around (e.g., surrounding, circumscribing) piston housing 311 with piston 306. Operation of solenoid coil 312 may be controlled by pump controller 314. Pump controller 314 may include memory and processing circuitry (e.g., one or more processors). In some embodiments, pump controller 314 may be a stand-alone controller, while in other embodiments, pump controller 314 may be a component of and / or integrated with another controller (e.g., control panel 40, controller 250) of vapor compression system 14. For example, pump controller 314 may include an embodiment of processing circuitry 252 and memory device 254 described above. The pump controller 314 may apply current to the solenoid coil 312, thereby inducing a magnetic force on the piston 306, causing the piston 306 to move in a forward direction 308 or a reverse direction 310, depending on the direction of the current flowing through the solenoid coil 312.

[0044] The pump 206 may include a compression chamber 316 (e.g., high-pressure chamber, liquid chamber, compression chamber) within a piston housing 311 that is fluidly coupled to the lubricant circuit 202 (e.g., inlet 300). The piston 306 may include a plunger section 318 configured to extend into the compression chamber 316 to pressurize the working fluid (e.g., during a compression stroke). During a return stroke, the plunger section 318 may be retracted from the compression chamber 316, thereby drawing working fluid into the compression chamber 316 through the inlet 300. For example, movement of the piston 206 in the return direction 310 increases the volume of the compression chamber 316, thereby creating a pressure differential across the inlet 300. As a result, working fluid may flow through the inlet 300 into the volume of the compression chamber 316 emptied by the retraction of the plunger section 318.

[0045] The inlet 300 may be a one-way valve (e.g., a check valve) configured to selectively allow working fluid to flow into the pump body 302, as shown. For example, the inlet 300 may include a hinged gate 320 (e.g., a hinged valve, a check valve, a valve, an inlet valve) or other valve member configured to pivot inward (e.g., open) toward the compression chamber 316. A pressure differential (e.g., a threshold pressure differential) across the hinged gate 320 may cause working fluid to push the hinged gate 320 open and flow into the compression chamber 316. In particular, the return stroke of the piston 306 may create a region of low pressure within the compression chamber 316 relative to the pressure of the working fluid upstream of the pump 206. As a result, the pump 206 may draw working fluid into the first chamber 206 during the return stroke. Inlet 300 may include a sealing seat 322 against which hinged gate 320 may rest in a normally closed position to block the flow of working fluid from compression chamber 316 out of inlet 300 (e.g., in an upstream direction). For example, when the pressure in compression chamber 316 is greater than the pressure upstream of inlet 300 (e.g., during a compression stroke), the higher pressure working fluid in compression chamber 316 may urge hinged gate 320 against sealing seat 322 to close inlet 300. In this manner, hinged gate 320 may allow the flow of working fluid to pump 206 (e.g., during a return stroke) while blocking the flow of working fluid in the opposite direction from pump 206 (e.g., during a compression stroke). In some embodiments, the hinged gate 320 may be biased toward the closed position (e.g., via a spring or other biasing element) such that the hinged gate 320 is configured to transition from the closed position toward the open position upon application of a threshold pressure differential (e.g., greater than zero) across the hinged gate 320. Thus, the inlet 300 may be in a closed position against the sealing seat 322 when no pressure differential exists across the hinged gate 320 (e.g., at the end of each stroke).

[0046] Outlet 304 may be a one-way valve (e.g., a check valve) configured to allow the flow of working fluid out of pump 206 toward bearing assembly 150 and to prevent the backflow of working fluid into pump 206. A pressure differential (e.g., a threshold pressure differential) across outlet 304 may cause outlet 304 (e.g., an outlet valve) to open, allowing the flow of working fluid therethrough. In particular, the compression stroke of piston 306 may create a region of high pressure in compression chamber 316 relative to lubricant circuit 202 downstream of pump 206. As a result, a valve (e.g., a ball valve) at outlet 304 may be biased open, and pump 206 may expel working fluid from compression chamber 316 and out outlet 304 during the compression stroke. As a result, inlet 300 and outlet 304 may open and close in coordination such that pump 206 maintains a continuous flow of pressurized working fluid through pump 206 and in a downstream direction toward bearing assembly 150. In some embodiments, the outlet 304 may include a check valve (e.g., a ball check valve) having a ball 324 and a spring 326 that biases the ball 324 toward a closed or sealing position (e.g., against the flow of working fluid).

[0047] In addition to the compression chamber 316, the pump 206 includes a piston cavity 328 (e.g., a second chamber, a low-pressure chamber, a vapor chamber) that may be separated from the compression chamber 316 by a wiper seal 330. The piston cavity 328 may be formed within and / or by the piston housing 311, and the piston 206 may be disposed within the piston cavity 328. A plunger section 318 of the piston 306 translates (e.g., reciprocates, oscillates) between the compression chamber 316 and the piston cavity 328. For example, during a return stroke, the plunger section 318 at least partially retracts from the compression chamber 316 and extends further into the piston cavity 328. During this translation, the plunger section 318 may maintain contact with the wiper seal 330 to at least partially block the flow of working fluid between the compression chamber 316 and the piston cavity 328. In some embodiments, wiper seal 330 may allow a portion of the working fluid to flow, such as in a controlled manner, from compression chamber 316 to piston cavity 328. Piston 306 also includes a head section 332 (e.g., a head portion) at the return end (e.g., first end) of plunger section 318. Head section 332 is configured to translate (e.g., reciprocate, oscillate) back and forth within piston cavity 328 (e.g., piston housing 311), thereby driving plunger section 318 into and out of compression chamber 316. As shown, head section 332 may have a larger diameter than plunger section 318.

[0048] Piston cavity 328 may contain vapor 341, such as working fluid in a gas phase. In some embodiments, vapor 341 may be a portion of the working fluid flowing from compression chamber 316 across wiper seal 330 and into piston cavity 328. Additionally, in some embodiments, pump 206 may include a bypass conduit 334 (e.g., bypass passage, bypass port) extending between (e.g., from and to) compression chamber 316 and piston cavity 328 to allow a portion of the working fluid (e.g., vapor 341) to bypass wiper seal 330 and flow from compression chamber 316 to piston cavity 328. As the working fluid enters piston cavity 328, the working fluid may vaporize (e.g., flash) due to a decrease in pressure. As head section 332 moves (e.g., translates, oscillates) within piston cavity 328, vapor 341 may flow across and cool the portion of piston 306 within piston cavity 328.

[0049] As discussed above, the piston 306 may be driven by a solenoid coil 312 that induces a magnetic force on the piston 306. In some cases, heat generated by magnetic induction may reduce the performance and / or lifespan of the pump 206. To facilitate cooling of the piston 306, the pump 206 may include a heat sink 336 (e.g., a heat dissipation element) coupled to the piston 306. The heat sink 336 may be formed from a non-magnetic material so that the induced magnetic force may not act on the heat sink 336 and / or generate heat within the heat sink 336. The heat sink 336 may be coupled (e.g., clipped) to the periphery of the piston 306. In some embodiments, the heat sink 336 may not contact the walls (e.g., inner walls) of the piston cavity 328. That is, a gap (e.g., a radial gap, gap, space) may extend between the heat sink 336 and the walls of the piston cavity 328. The vapor working fluid (e.g., vapor 341) in the piston cavity 328 may flow across the heat sink 336 (e.g., during a compression stroke) to enable cooling of the piston 306 (e.g., via heat transfer from the heat sink 336 and / or the piston 306 to the vapor working fluid). In some embodiments, the vapor 341 may also absorb heat from the solenoid coil 312. In some embodiments, the pump 206 may include a bleed vent 338 through which the vapor 341 may exit the pump 206 from the piston cavity 328. The bleed vent 338 may direct the vapor 341 (e.g., vapor working fluid) to the working fluid circuit 200, for example, to selected components of the working fluid circuit 200 (e.g., the evaporator 38, the compressor 32, the drain line 226).

[0050] The pump 206 may include one or more piston rings 340 disposed around the piston 306 (e.g., head section 332). In some embodiments, the piston rings 340 may be configured to control the flow of steam 341 within the piston cavity 328. To this end, at least one of the piston rings 340 may be ported (e.g., including one or more ports 339, such as axial ports, formed therein) or may include notches to allow the steam 341 to flow across the piston 306 and into the piston cavity 328 in a desired manner. In this manner, the piston rings 340 may be configured to allow the steam 341 to flow across the piston 306 and throughout the piston cavity 328, enabling cooling of the piston 306 via the steam 341. Additionally, the piston rings 340 may be configured to contact the walls of the piston cavity 328, thereby enabling heat transfer between the piston 306, the piston housing 311, and the working fluid.

[0051] The operation of the pump 206 may be controlled by a pump controller 314. To this end, the pump controller 314 may supply or control the supply of current to the solenoid coil 312. The pump controller 314 may adjust the magnitude and / or other characteristics of the current to control the magnitude of the magnetic force generated by the solenoid coil 312 and applied to the piston 306. Additionally, the pump controller 314 may change the direction of the current through the solenoid coil 312 to reverse the polarity of the solenoid coil 312 and, consequently, the direction of the magnetic force acting on the piston 306. For example, to drive the piston 306 in the forward direction 308 at a particular acceleration, the pump controller 314 may direct the current through the solenoid coil 312 at a particular magnitude (e.g., amperage) and in a particular direction. To decrease the acceleration of the piston 306, the pump controller 314 may decrease the magnitude of the current. To decelerate the piston 306 or change its direction (e.g., from the forward direction 308 to the return direction 310), the pump controller 314 may reverse the direction of the current through the solenoid coil 312. In this manner, the motion (e.g., velocity, acceleration, force, momentum, kinetic energy) of the piston 306 within the piston housing 311 may correspond to the electrical input (e.g., current, voltage, power) provided to the solenoid coil 312. In some embodiments, the pump controller 314 may control the electrical input based on a current profile configured to achieve a desired motion pattern of the piston 306. For example, the current profile for the compression stroke of the piston 306 may be a function of current versus time selected to accelerate the piston 306 in the forward direction 308 for a particular period of time, decelerate it for another period of time, and then reverse direction for the return stroke. However, the operating conditions of the pump 206 (e.g., deadheading) may cause variations in the behavior of the pump 206 given a particular current profile. Additionally, cavitation of the working fluid can occur under certain operating conditions, such as when the return stroke of the piston 306 is too fast.Therefore, it may be desirable to adjust the current profile in response to the speed or frequency of the pump 206 (eg, piston 306), which may be determined based on sensed operating conditions.

[0052] The pump 206 includes a respective bump stop 342 at each end of the piston cavity 328. Each bump stop 342 may be configured to mechanically stop the piston 306 in response to contact between the bump stop 342 and the piston 306. In the illustrated embodiment, the pump 206 includes two bump stops 342, such as a forward bump stop 343 and a return bump stop 345. Each bump stop 342 is disposed at a respective end of the travel of the head section 332 within the piston cavity 328. As discussed in further detail below, the bump stops 342 may provide a mechanical stop for the piston 306 at the end of each stroke. Additionally, each bump stop 342 may include an internal switch 344 (e.g., an internal switch mechanism) configured to provide a signal to the pump controller 314 indicative of contact between the piston 306 and the bump stop 342. To enable electrical communication between the bump stop 342, the pump controller 314, and / or the solenoid coil 312, the pump 206 may include an electrical feedthrough 346 through which an electrical conduit (e.g., a wire) may extend to electrically couple the pump controller 314 to one or more components (e.g., the internal switch 344) of the pump 206. For example, a wire 348 may extend through the electrical feedthrough 346 and connect the pump controller 314 to contacts of one or more of the internal switches 333 of the bump stop 342. Additionally, the wire 348 may provide electrical current from the power source and / or the pump controller 314 to the solenoid coil 312, enabling operation of the pump 206 in the manner described above.

[0053] 8 and 9 illustrate schematic cross-sectional side views of a portion of one embodiment of piston 306 illustrating the operation of the internal switch 344 of one of the forward bump stops 343. For example, the illustrated embodiment shows contact between piston 306 and forward bump stop 343 (e.g., first bump stop) at the end of the compression stroke. While FIGS. 8 and 9 illustrate forward bump stop 343 at the forward end of piston cavity 328, the techniques described in the following discussion may be equally applicable to a second bump stop (e.g., return bump stop 345) located at the opposite return end of piston 306.

[0054] The front bump stop 343 includes a body 370 that may be formed from a conformable (e.g., compressible), non-conductive material such as an elastomer (e.g., silicone, rubber). Thus, the front bump stop 343 may be configured to at least partially absorb forces applied to the body 370 during contact between the front bump stop 343 and the piston 306. In this manner, the front bump stop 343 may be configured to rest (e.g., rest) the piston 306 in a controlled manner at the end of its stroke. The internal switch 344 of the front bump stop 343 includes a suspended contact 372 encased within the body 370 such that the suspended contact 372 is movable in response to application of a force to the body 370 (e.g., during compression of the body 370). Additionally, the front bump stop 343 includes a contact 374 that is stationary relative to the pump 206 (e.g., relative to the body 370 and / or the suspended contact 372). For example, the fixed contact 374 may be coupled to the pump body 370 such that the fixed contact 374 does not move when the piston 306 contacts and compresses the body 302. The fixed contact 374 may include a first flange 376 disposed around (e.g., annularly around) the body 370 and a second flange 378 extending radially toward (e.g., into) the body 370. The second flange 378 may contact the suspended contact 372 when the body 370 is in an uncompressed or resting state of the forward bump stop 343, as shown in FIG. 8 . That is, the body 370 may resiliently bias the suspended contact 372 into abutment against the fixed contact 374, thereby establishing electrical continuity between the suspended contact 372 and the fixed contact 374. In this manner, the electrical connection between the suspended contact 372 and the fixed contact 374 may be normally closed. As will be appreciated, contact (e.g., electrical continuity) between the suspended contact 372 and the fixed contact 374 may indicate a lack of contact between the piston 306 and the bump 342. Thus, detection of an electrical discontinuity between the suspended contact 372 and the fixed contact 374 may indicate that the piston 306 has reached the end of its compression stroke.

[0055] As shown in FIG. 9 , the piston 306 may contact (e.g., impact, abut) the body 370 of the forward bump stop 343 at the end of the compression stroke. As a result, the body 370 may compress (e.g., elastically deform), and the force of the piston 306 may translate the suspended contact 372 in the forward direction 308, temporarily severing the physical contact, and therefore the electrical connection, between the fixed contact 374 and the suspended contact 372. Then, in some examples, the motion of the piston 306 may reverse (e.g., rebound) away from the forward bump stop 343 (e.g., in the reverse direction 310) as the body 370 decompresses and returns to a resting or undeformed state. As a result, the suspended contact 372 may return to contact with the fixed contact 374, thereby reestablishing the electrical connection therebetween.

[0056] The pump controller 314 may monitor electrical continuity between the suspended contact 372 and the fixed contact 374 to detect impact of the piston 306 against the forward bump stop 343, which may correspond to the end of the compression stroke. For example, the pump controller 314 may monitor a probe wire 380 extending through the electrical feedthrough 346 to measure the voltage between (e.g., across) the fixed contact 374 and the suspended contact 372. A low (e.g., zero) detected voltage may indicate contact (e.g., physical contact) between the fixed contact 374 and the suspended contact 372. A high (e.g., greater than zero) detected voltage may indicate no contact (e.g., physical separation) between the fixed contact 374 and the suspended contact 372. In response to detecting that the fixed contact 374 is not in contact with the suspended contact 372, the pump controller 314 may determine that the piston 306 is at the end of a stroke.

[0057] In response to detecting the impact of the piston 306 against one of the bump stops 342, the pump controller 314 may reverse the direction of current supplied to the solenoid coil 312 to reverse the direction of movement of the piston 306 within the piston housing 311. For example, in response to detecting a disconnection between the suspended contact 372 and the fixed contact 374 of the forward bump stop 343, the pump controller 314 may reverse the direction of current conducted through the solenoid coil 312 to move the piston in the return direction 310, thereby initiating the return stroke after the piston 306 completes its compression stroke. The motion profile (e.g., speed or acceleration over time) of each stroke may be controlled based on the current profile. For example, the current profile may map current values ​​to nominal or expected acceleration values. The pump controller 314 may then achieve the desired acceleration value by supplying a corresponding current value based on the current profile.

[0058] In some situations (e.g., under certain operating conditions), the current profile may be adjusted (e.g., via the pump controller 314) to enable coordinated operation of the piston 306. For example, the current profile may be adjusted based on one or more detected operating parameters and / or operating conditions of the pump 206. In some embodiments, the current profile may be adjusted to avoid and / or mitigate cavitation and / or conditions indicative of cavitation within the pump 206. For example, depending on the operating conditions (e.g., the temperature of the working fluid) and the speed of the pump 206, the return stroke may introduce localized regions of low pressure within the pump 206 where the working fluid may cavitate. Such cavitation of the working fluid can result in inefficiency and wear on the pump 206. Therefore, the pump controller 314 may utilize the methods described herein to adjust the movement of the piston 306 (e.g., the speed of the return stroke) to reduce cavitation.

[0059] FIG. 10 illustrates a flowchart of one embodiment of a method 400 that may be implemented by the pump controller 314 to adjust the operation (e.g., movement) of the piston 306, such as based on sensed feedback or data (e.g., feedback indicative of cavitation or potential cavitation). For example, the pump controller 314 may determine a change in the spacing, duration, frequency, and / or speed of the strokes (e.g., consecutive strokes) of the piston 306 from one stroke cycle to the next, such as based on the duration or interval between physical contact of the piston 306 with each of the bump stops 342. The change may be indicative of cavitation caused by operation of the pump 206 with the current profile under particular operating conditions. The pump controller 314 may then adjust the current profile to reduce the likelihood and / or instances of cavitation.

[0060] In block 402, the pump controller 314 may cause the piston 306 to perform a compression stroke. For example, the pump controller 314 may energize (e.g., supply current to) the solenoid coil 312 in a direction and magnitude according to a particular current profile. The direction and magnitude of the current may be constant or variable throughout the stroke, resulting in a controlled velocity profile of the piston 306. For example, the current profile may initially accelerate the piston 306 forward and then decelerate toward the end of the compression stroke. In this manner, the pump controller 314 may energize the solenoid coil to induce a desired magnetic force on the piston in a first direction (e.g., forward, compression direction).

[0061] At the end of the compression stroke, the piston 306 may contact a front bump stop 343 (e.g., a first bump stop) at the front end of the piston cavity 328. As a result, in block 404, the pump controller 314 may detect contact with the front bump stop 343 based on a disconnection between the fixed contact 374 and the suspended contact 372. The internal switch 344 may send a signal to the pump controller 314 indicating contact with the front bump stop 343.

[0062] In block 406, the pump controller 314 may determine the speed of the compression stroke based on the interval between the contact time at the front bump stop 343 and the preceding contact time at the return bump stop 345 (e.g., the second bump stop). The time interval between these two contact moments may correspond to the speed of the compression stroke. For example, at the end of the return stroke, the piston 306 may hit the return bump stop 345 at time t1. Then, at the end of the compression stroke, the piston 306 may hit the front bump stop 343 at time t2. The pump controller 314 may then determine that the interval is t2-t1. Based on the interval, the pump controller 314 may determine the speed of the compression stroke. Alternatively, the pump controller 314 may determine the duration or frequency of the pump cycle based on the contact time at the front bump stop 343 and the previous contact time at the front bump stop. For example, the pump controller 314 may detect a first contact at the front bump stop 343 at time t1, and then detect a second contact at the front bump stop 343 at time t2. The pump controller 314 may then determine the duration of a pump cycle to be t2-t1. In either case, the pump controller 314 determines the time interval between subsequent contacts at one or both of the bump stops 342.

[0063] In block 408, the pump controller 314 may compare the speed of the compression stroke to the speed of a previous compression stroke (e.g., the immediately preceding compression stroke) of the piston 306. For example, the pump controller 314 may compare the time interval determined in block 406 to the previous time interval for the previous compression stroke. Based on the comparison between the two intervals, the pump controller 314 may determine a difference (e.g., change) in the speed of the compression stroke and the previous compression stroke. For example, the pump controller 314 may determine that the most recent compression stroke is 100 milliseconds slower than the previous compression stroke. A decrease in the speed of the compression stroke may be an indication of cavitation during the return stroke.

[0064] In block 410, the pump controller 314 may determine whether the change in the speed of the compression stroke from the previous compression stroke is greater than a threshold amount (e.g., zero, 10 milliseconds, 100 milliseconds, etc.). If so (i.e., the difference is significant enough), in block 412, the pump controller 314 may adjust the current profile based on the difference. For example, the pump controller 314 may adjust the current profile to reduce the speed (e.g., average speed, acceleration) of the return stroke to avoid further cavitation. Then, in block 414, the pump controller 314 may supply current to initiate the return stroke based on the adjusted current profile. In this way, the pump controller 314 may use the change in the speed of the compression stroke as feedback to control the current through the solenoid coil 312.

[0065] In block 416, the pump controller 314 may detect contact between the piston 306 and the return bump stop 345. In some embodiments, the pump controller 314 may start a timer or store the time when contact at the return bump stop 345 occurs. In this manner, the interval between contact at the return bump stop 345 and subsequent contact at the forward bump stop 343 may be determined. In response to detecting contact at the return bump stop 345, the pump controller 314 may return to block 402 and supply current to the solenoid coil 312 to initiate the compression stroke. For example, the pump controller 314 may reverse the polarity of the solenoid coil 312, causing the piston 306 to reverse direction 308.

[0066] While only certain features and embodiments have been illustrated and described, numerous modifications and variations may occur to those skilled in the art, such as changes in the size, dimensions, structure, shape, and proportions of various elements, values ​​of parameters such as temperature and pressure, mounting arrangements, use of materials, color, orientation, 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 rearranged according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and variations that fall within the true spirit of the present disclosure.

[0067] Moreover, in an effort to provide a concise description of exemplary embodiments, all features of an actual implementation may not be described, such as those not relevant to the best mode currently contemplated or not relevant to enablement. It will be understood that in developing any such actual implementation, as with any engineering or design project, numerous implementation-specific decisions will be made. While such a development effort might be complex and time-consuming, it would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill in the art having the benefit of this disclosure without undue experimentation.

[0068] The technology presented and claimed herein refers to and applies to tangible objects and examples of practical nature that clearly improve the art, and is therefore not abstract, intangible, or purely theoretical. Furthermore, if any claim appended at the end of this specification contains one or more elements designated as "means for [performing] ... [function]" or "steps for [performing] ... [function]," it is intended that such elements be construed under 35 U.S.C. 112(f). However, for any claim containing elements designated in any other manner, it is intended that such elements not be construed under 35 U.S.C. 112(f).

Claims

1. 1. A pump for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a pump body defining a compression chamber; a piston housing coupled to the pump body, the piston housing including a piston cavity; a piston disposed within the piston housing, the piston comprising: a plunger section configured to reciprocate between the compression chamber and the piston cavity; a piston comprising: a head section configured to reciprocate within the piston cavity; a solenoid coil configured to induce a magnetic force on the piston; a controller configured to control the flow of current through the solenoid coil to control the reciprocating movement of the piston within the piston cavity.

2. The pump body is an inlet configured to direct fluid into the compression chamber; an outlet configured to discharge the fluid from the compression chamber; 2. The pump of claim 1, wherein the piston is configured to translate in a first direction to draw the fluid into the compression chamber through the inlet and to translate in a second direction opposite the first direction to force the fluid out of the compression chamber through the outlet.

3. 3. The pump of claim 2, comprising an inlet valve disposed at the inlet and an outlet valve disposed at the outlet, wherein the inlet valve is configured to transition to a first open position and the outlet valve is configured to transition to a first closed position while the piston translates in the first direction, and the inlet valve is configured to transition to a second closed position and the outlet valve is configured to transition to a second open position while the piston translates in the second direction.

4. 4. The pump of claim 3, wherein the inlet valve comprises a hinged gate, the outlet valve comprises a ball check valve, or both.

5. The piston housing a first bump stop disposed within the piston cavity, the piston configured to contact the first bump stop at the end of a compression stroke of the piston; and 2. The pump of claim 1, further comprising: a second bump stop disposed within the piston cavity, the piston configured to contact the second bump stop at the end of the piston's return stroke.

6. 6. The pump of claim 5, wherein the first bump stop comprises a first electrical contact communicatively coupled to the controller and a second electrical contact communicatively coupled to the controller, the controller configured to detect contact between the piston and the first bump stop in response to detecting an electrical discontinuity between the first electrical contact and the second electrical contact.

7. 7. The pump of claim 6, wherein the first bump stop comprises a compliant body, the first electrical contact is a fixed contact, and the second electrical contact is a suspended contact disposed within the compliant body, the suspended contact configured to establish electrical continuity with the fixed contact in an uncompressed state of the compliant body, the compliant body configured to transition to a compressed state in response to contact with the piston, and the compliant body configured to separate the suspended contact from the fixed contact in the compressed state to establish electrical discontinuity between the suspended contact and the fixed contact.

8. The controller is communicatively coupled to the first bump stop and the second bump stop, the controller comprising: detecting contact between the piston and the first bump stop based on one or more first signals received from the first bump stop; detecting contact between the piston and the second bump stop based on one or more second signals received from the second bump stop; determining a stroke velocity of the piston based on the one or more first signals and the one or more second signals; Detecting a change in the stroke velocity; The pump of claim 5 configured to adjust the current flow based on the change in stroke rate.

9. 2. The pump of claim 1, further comprising a bypass conduit extending through the pump body, the piston housing, or both, the bypass conduit extending between the compression chamber and the piston cavity, the bypass conduit configured to allow fluid flow between the compression chamber and the piston cavity.

10. 10. The pump of claim 9, comprising one or more piston rings coupled to the head section of the piston, the piston rings configured to permit flow of the fluid across the head section from a first end of the head section to a second end of the head section.

11. The pump of claim 1 , further comprising a non-magnetic heat sink disposed around the head section of the piston.

12. A heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system comprising: a pump configured to pump fluid along a circuit of the HVAC&R system, the pump comprising: a piston configured to reciprocate within a piston chamber of the piston housing; a bump stop disposed at an end of the piston chamber, the bump stop including an internal switch configured to detect contact between the bump stop and the piston; a controller configured to control a stroke rate of the piston based on a signal received from the internal switch.

13. 13. The HVAC&R system of claim 12, comprising: the piston housing; and a solenoid coil disposed about the piston housing, the solenoid coil configured to induce a magnetic force to move the piston within the piston chamber, and the controller configured to adjust a flow of current through the solenoid coil to control the stroke speed of the piston.

14. 14. The HVAC&R system of claim 13, wherein the controller is configured to adjust a current profile of the flow of current through the solenoid coil based on contact detected between the bump stop and the piston.

15. The pump includes a piston housing and a pump body of the pump, the piston housing and the pump body being coupled to each other, and the piston a plunger section configured to extend into a compression chamber of the pump body to pressurize the fluid during a compression stroke of the piston; 13. The HVAC&R system of claim 12, comprising: a head section configured to reciprocate within the piston chamber of the piston housing.

16. 16. The HVAC&R system of claim 15, wherein the piston housing comprises a piston cavity, and the pump body, the piston housing, or both comprise a bypass passage configured to allow flow of the fluid from the compression chamber to the piston cavity for cooling the piston.

17. 13. The HVAC&R system of claim 12, comprising: the circuit; and a compressor configured to circulate a working fluid through a working fluid circuit of the HVAC&R system, the compressor including a bearing, the circuit extending between the working fluid circuit and the bearing, the fluid including a portion of the working fluid, and the pump configured to pump the fluid along the circuit to the bearing.

18. 1. A method of operating a pump, comprising: energizing a solenoid coil to translate the piston in a first direction within the piston cavity; Detecting a first contact between the piston and a first bump stop within the piston cavity; energizing the solenoid coil to translate the piston within the piston cavity in a second direction opposite the first direction; detecting a second contact between the piston and a second bump stop within the piston cavity; determining a time interval between the first contact and the second contact; and adjusting energization of the solenoid coil based on a difference between the time interval and a previous time interval.

19. 20. The method of claim 18, wherein detecting the first contact comprises detecting a first electrical discontinuity in a first internal switch of the first bump stop, and detecting the second contact comprises detecting a second electrical discontinuity in a second internal switch of the second bump stop.

20. 20. The method of claim 18, wherein adjusting the energization of the solenoid coil comprises adjusting a flow of current through the solenoid coil to translate the piston in the first direction within the piston cavity.

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