Compact hydraulic variable geometry regulation system of a compressor for a heating, ventilation, air conditioning, and / or refrigeration system

Abstract

A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a compact hydraulic variable geometry diffuser (VGD) regulation system. The compact hydraulic VGD regulation system includes an actuator assembly fluidly coupled to a VGD piston assembly. The VGD piston assembly may be configured to control a position of a VGD ring within a compressor. In particular, activation of the motor pistons, each coupled to a same actuator, causes approximately equal displacement of each of the VGD pistons of the VGD piston assembly. As such, the compact hydraulic VGD regulation system enables efficient control of the position of the VGD ring, while reducing misalignment of the VGD ring within the compressor. Therefore, the compact hydraulic VGD regulation system increases efficiency of the compressor and thus improves efficiency of the HVAC&R system.

Description

COMPACT HYDRAULIC VARIABLE GEOMETRY REGULATION SYSTEM OF A COMPRESSOR FOR A HEATING, VENTILATION, AIR CONDITIONING, AND / OR REFRIGERATION SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from and the benefit of U.S. Provisional Patent Application No. 63 / 536,644, entitled “COMPACT HYDRAULIC VARIABLE GEOMETRY REGULATION SYSTEM OF A COMPRESSOR FOR A HEATING, VENTILATION, AIR CONDITIONING, AND / OR REFRIGERATION SYSTEM,” filed September 5, 2023, 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] Chiller systems, or vapor compression systems, utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the chiller system. The chiller system may place the working fluid in a heat exchange relationship with a cooling fluid (e.g., water) and may deliver the cooling fluid to conditioning equipment and / or a conditioned environment serviced by the chiller system. In such applications, the cooling fluid may be directed through downstream equipment, such as air handlers, to condition other fluids, such as air in a building. The chiller system may include a compressor configured to pressurize the working fluid and circulate theworking fluid through a working fluid circuit. Unfortunately, the compressor may be susceptible to inefficient or undesirable operations.SUMMARY

[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 certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0005] In an embodiment, a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system includes a vapor compression circuit and a compressor fluidly coupled to the vapor compression circuit. The compressor includes a diffuser passage, and a variable geometry diffuser (VGD) regulation system. The VGD regulation system includes a motor piston coupled to an actuator, a VGD piston fluidly coupled to the motor piston, and a VGD ring disposed within a diffuser inlet of the diffuser passage, wherein the VGD piston is coupled to the VGD ring, and wherein the actuator is configured to control a position of the VGD ring with respect to the diffuser inlet via the motor piston and the VGD piston.

[0006] In an embodiment, a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system includes a vapor compression circuit. The vapor compression circuit is configured to circulate working fluid therein. In addition, the HVAC&R system includes a compressor of the vapor compression circuit, wherein the compressor is configured to compress a flow of the working fluid. The compressor includes a diffuser inlet of a diffuser passage configured to receive the flow of the working fluid, and a variable geometry diffuser (VGD) regulation system configured to adjust a volume of the flow of the working fluid through the diffuser inlet. The VGD regulation system includes a first motor piston, a second motor piston, and a third motor piston coupled to an actuator. The VGD regulation system also includes a first VGD piston fluidly coupled to the first motor piston,a second VGD piston fluidly coupled to the second motor piston, and a third VGD piston fluidly coupled to the third motor piston. Actuation of the first motor piston, the second motor piston, and the third motor piston, via the actuator, is configured to cause actuation of the first VGD piston, the second VGD piston, and the third VGD piston. The VGD regulation system also includes a VGD ring disposed at the diffuser inlet, wherein the first VGD piston, the second VGD piston, and the third VGD piston are coupled to the VGD ring. The HVAC&R system additionally includes a controller communicatively coupled to the actuator. The controller is configured to control the volume of the flow of the working fluid through the diffuser inlet by adjusting a position of the VGD ring with respect to the diffuser inlet via the actuator.

[0007] In an embodiment, a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system includes a vapor compression circuit and a compressor fluidly coupled to the vapor compression circuit. The compressor includes a diffuser inlet of a diffuser passage. The HVAC&R system further includes a variable geometry diffuser (VGD) regulation system associated with the compressor. The VGD system includes an actuator, a first motor piston coupled to the actuator and fluidly coupled to a first VGD piston, a second motor piston coupled to the actuator and fluidly coupled to a second VGD piston, a third motor piston coupled to the actuator and fluidly coupled to a third VGD piston, and a VGD ring disposed at the diffuser inlet. The first motor piston, the second motor piston, and the third motor piston are configured to cause actuation, via the actuator, of the VGD ring via the first VGD piston, the second VGD piston, and the third VGD piston.DRAWINGS

[0008] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0009] 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;

[0010] FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0011] FIG. 3 is a schematic diagram of an embodiment of the vapor compression system of FIG. 2, in accordance with an aspect of the present disclosure;

[0012] FIG. 4 is a schematic diagram of an embodiment of the vapor compression system of FIG. 2, in accordance with an aspect of the present disclosure;

[0013] FIG. 5 is a cross-sectional side view of an embodiment of a portion of a compressor of the HVAC&R system having a compact hydraulic variable geometry diffuser (VGD) regulation system, in accordance with an aspect of the present disclosure;

[0014] FIG. 6 is a perspective view of an embodiment of a hydraulic VGD ring assembly of the compact hydraulic VGD regulation system, in accordance with an aspect of the present disclosure;

[0015] FIG. 7 is a cross-sectional perspective view of a portion of an embodiment of the hydraulic VGD ring assembly of FIG. 6, in accordance with an aspect of the present disclosure;

[0016] FIG. 8 is a perspective view of an embodiment of a hydraulic actuator assembly of the compact hydraulic VGD regulation system, in accordance with an aspect of the present disclosure;

[0017] FIG. 9 is a cross-sectional perspective view of an embodiment of the hydraulic actuator assembly of FIG. 8, in accordance with an aspect of the present disclosure;

[0018] FIG. 10 is a cross-sectional perspective view of an embodiment of the hydraulic actuator assembly of FIG. 8 and cross-sectional front views of piston assembly options, in accordance with an aspect of the present disclosure;

[0019] FIG. 11 is a cross-section perspective view of an embodiment of a hydraulic actuator assembly of the compact hydraulic VGD regulation system, in accordance with an aspect of the present disclosure; and

[0020] FIG. 12 is a schematic diagram of an embodiment of the compact hydraulic VGD regulation system of FIG. 5, in accordance with an aspect of the present disclosure.DETAILED DESCRIPTION

[0021] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are 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.

[0022] 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 of the 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 “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0023] As used herein, the terms “approximately,” “generally,” “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand.For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to, “same” as) a given value, this is intended to convey that the property value may be within + / - 5%, within + / - 4%, within + / - 3%, within + / - 2%, within + / - 1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” or “generally parallel” to another feature, “generally cross-wise” to another feature, and so forth, this is intended to convey that the given feature is within + / - 5%, within + / - 4%, within + / - 3%, within + / - 2%, within + / - 1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular or cross-wise to another feature, and so forth. Mathematical terms, such as “parallel” and “perpendicular,” should not be rigidly interpreted in a strict mathematical sense, but should instead be interpreted as one of ordinary skill in the art would interpret such terms. For example, one of ordinary skill in the art would understand that two lines that are substantially parallel to each other are parallel to a substantial degree, but may have minor deviation from exactly parallel.

[0024] Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system including a vapor compression system (e.g., vapor compression circuit) having a compressor, such as a centrifugal compressor including one or more stages (e.g., single stage, multistage, compact dual stage, compact triple stage). In operation, the compressor may pressurize a working fluid within the vapor compression system and direct the working fluid to a condenser, which may cool and condense the working fluid. The condensed working fluid may be directed to an expansion device, which may reduce a pressure of the working fluid, further cooling the working fluid. From the expansion device, the cooled working fluid may be directed to an evaporator, where the working fluid may be placed in a heat exchange relationship with a cooling fluid to cool the cooling fluid.

[0025] In some embodiments, the compressor may include an impeller configured to rotate to pressurize the working fluid and to direct the working fluid to a diffuser passage of the compressor. For example, the impeller may be coupled to a shaft, and the shaft maybe configured to rotate relative to a housing of the compressor to drive rotation of the impeller relative to the housing. In some embodiments, the compressor may be a centrifugal compressor with one or more stages. For example, the compressor may be a multistage centrifugal compressor in which each stage includes a respective inlet (e.g., passage for the working fluid to enter a respective stage), an impeller, and a diffuser passage (e.g., passage for the working fluid to exit the respective stage). Furthermore, the multistage stage centrifugal compressor may include one or more regulation systems (e.g., head regulation systems, capacity regulation systems) to improve efficiency and performance of the compressor by reducing unstable and / or inconsistent work fluid flows within the compressor mitigating surges and / or stalls (e.g., diffuser stalls) during operation, while also reducing undesirable vibration and noise. Substantially high levels of vibration of the compressor may cause damage to the compressor and / or a system in which the compressor is implemented. The one or more regulation systems may affect a capacity of the compressor, and / or may affect a head of the compressor, or an amount of energy required to move a unit mass of fluid from one point to another. Examples of the one or more regulation systems may be a pre-rotary vane regulation system, which may affect both the head and the capacity of the compressor, a variable geometry diffuser (VGD) regulation system, which may efficiently affect the capacity, a variable speed drive (VSD) regulation system, which may affect the head with high efficiency, a gas bypass regulation system, which is generally used for low capacity reduction and / or during transient operations such as startup of the compressor, and an injection flow regulation system. Specifically, for multistage centrifugal compressors, including the VGD regulation system may lead to higher efficiency of the centrifugal compressors during operation by reducing undesirable noise and vibration and / or reducing instability or inconsistency of flow within the compressor to prevent surges and / or stalls.

[0026] In particular, the VGD regulation system may include at least one VGD actuator coupled to a VGD component (e.g., VGD ring) that is controllably actuated (e.g., moved, translated, axially translated) by the VGD actuator to vary a size of a diffuser gap (e.g., space, passage, opening) within the diffuser passage. To this end, the VGD componentmay be actuated to physically extend across and substantially block at least a portion of the diffuser passage. In this way, the VGD regulation system may controllably increase or decrease a flow rate of the working fluid through the diffuser passage and / or reduce back flow of the working fluid during low speed and / or low capacity operations. Specifically, for multistage centrifugal compressors, the VGD regulation system may include at least one respective VGD component for each diffuser passage per stage of the multistage compressor. Due to the multiple stages of the multistage centrifugal compressors, maintaining stable rotor dynamics, or management of lateral and torsional vibrations, is critical to ensure proper operation and efficiency of the multistage centrifugal compressor, especially in multistage centrifugal compressors that include a VSD. To achieve stability at higher revolutions per minute (RPM), and thus proper operation and efficiency of the multistage centrifugal compressor, it is desirable to reduce an overall length of the shaft of the centrifugal compressor to produce a more compact design (e.g., decrease a distance between one or more bearings of the compressor and the impeller of a first stage of the compressor). However, implementing the compact design of the compressor limits space available for each stage of the multistage centrifugal compressor along the shaft, and thus may limit available space for the VGD regulation system design (e.g., installation of VGD components and / or one or more VGD actuators to actuate the VGD components).

[0027] Traditional designs incorporating a VGD regulation system into a multistage centrifugal compressor (e.g., VSD multistage centrifugal compressor) may utilize hydraulic VGD actuators to actuate the VGD component. Using hydraulic VGD actuators may reduce an overall size and / or space (e.g., overall footprint) that the VGD regulation system may occupy within each respective stage of the centrifugal compressor. For example, each of the VGD components may include a single piston actuator (e.g., motor apparatus) for controlling two or more hydraulic actuators (e.g., separate hydraulic actuators) to actuate and / or control a position of the VGD component within the respective diffuser passage. However, conventional designs may lead to misalignment of the VGD component within the diffuser passage, leakages of hydraulic fluid (e.g., oil) used to control actuation of the hydraulic VGD actuators, and / or discrepancies between an actual VGDcomponent position within the diffuser passage and an expected VGD component position. In addition, conventional designs may produce flow (e.g., aeraulic) inefficiencies within the centrifugal compressor and reduce an overall efficiency of the compressor.

[0028] As an example, hydraulic fluid leakages and / or varying loads experienced by the two or more hydraulic actuators (e.g., due to circumferential pressure gradients induced by scroll geometry) may cause the VGD component to become misaligned within the diffuser passage of the centrifugal compressor. This may reduce efficient control of the VGD component within the diffuser passage, as an actual position of the VGD component may be different than an expected position of the VGD component. In addition, misalignment of the VGD component may impair a desired retracted position (e.g., position that does not block the diffuser passage) of the VGD component. Traditionally, to accommodate possible misalignment of the VGD component, a size of a gap within the compressor housing in which the VGD component retracts into may be increased. However, increasing the gap (e.g., increasing clearance between a gap edge and the VGD component) may cause flow (e g., aeraulic) inefficiencies. In particular, flow inefficiencies may be due to gas and / or fluid bypassing behind the VGD component and / or creating local turbulences where the clearance between the gap edge and the VGD component has been increased. Therefore, it is now recognized that utilizing conventional hydraulic VGD actuators may be limiting and, during operation, may produce inefficient control of VGD components and / or inefficient flow patterns within the compressor, and thus reduce an overall inefficiency of the compressor.

[0029] Thus, it is now recognized that an improved VGD regulation system (e.g., VGD system) is desirable for a compressor that includes concurrently operated (e.g., controlled, simultaneously controlled) hydraulic VGD actuators to improve efficiency and performance of the compressor. In particular, the improved VGD regulation system may reduce misalignment of the VGD component(s), thus reducing instability or inconsistency of flow (e.g., air flow, fluid flow) within the compressor. Accordingly, the present disclosure is directed to a compact hydraulic VGD regulation system (e.g., compact VGDsystem) of a compressor (e.g., centrifugal compressor) for an HVAC&R system. The compact hydraulic VGD regulation system may efficiently control a position of the VGD component(s), thus improving efficient control of compressor capacity (e.g., centrifugal compressor capacity) while reducing inefficient flow patterns within the compressor. In particular, as described in more detail below, the compact hydraulic VGD regulation system may enable operation via a load compensation system (e.g., an unequal load compensation system) to efficiently control a position of the VGD component and reduce misalignment of the VGD component within the compressor (e.g., within the diffuser passage). Therefore, the present embodiments of the compact hydraulic VGD regulation system may reduce flow inefficiencies and increase confidence of an expected control of the position of the VGD component(s). In addition, the compact hydraulic VGD regulation system may reduce hydraulic fluid leakages, which additionally increases efficient control of a position of the VGD component, and thus increases an overall efficiency of the compressor.

[0030] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system 10 in a building 12 for a typical commercial setting. The HVAC&R system 10 may include a vapor compression system 14 (e.g., a chiller, a heat pump) that supplies a chilled liquid, which may be used to cool the building 12. The HVAC&R 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&R system 10. The HVAC&R system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC&R system 10 mayinclude air handlers 22 and / or other components that may be shared between or among floors.

[0031] FIGS. 2 and 3 are embodiments of the vapor compression system 14 that can be used in the HVAC&R system 10. The vapor compression system 14 may circulate a refrigerant (e.g., working fluid) through a circuit starting with a compressor 32 (e.g., centrifugal compressor, multistage compressor, single stage compressor). 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 that has an analog to digital (A / D) converter 42, a microprocessor 44, a non-volatile memory 46, and / or an interface board 48.

[0032] Some examples of fluids that may be used as refrigerants in the vapor compression system 14 are hydrofluorocarbon (HFC) based refrigerants, for example, R- 410A, R-407, R-134a, R-1233zd, R-1234ze, hydrofluoro olefin (HFO), "natural" refrigerants like ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbonbased refrigerants, water vapor, or any other suitable refrigerant. In some embodiments, the vapor compression system 14 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, versus 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.

[0033] 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 anytype of 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.

[0034] 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 including one or more compressor stages (e.g., compact dual stage compressor (CDS), multistage compressor, compact triple stage compressor (CTS)). 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 liquid refrigerant 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 34.

[0035] The liquid refrigerant 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 liquid refrigerant in the evaporator 38 may undergo a phase change from the liquid refrigerant 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 vapor refrigerant exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

[0036] FIG. 4 is a schematic 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, an economizer, etc.). 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 liquid refrigerant 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.

[0037] Additionally, the intermediate vessel 70 may provide for further expansion of the liquid refrigerant because of a pressure drop experienced by the liquid refrigerant 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 (e.g., an interstage line) 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 liquid refrigerant 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.

[0038] It should be appreciated that any of the features described herein may be incorporated with the vapor compression system 14 or any other suitable HVAC&R systems. For example, the present techniques may incorporate embodiments of theHVAC&R system 10, the vapor compression system 14, the boiler 16, a chiller, a heat pump, and / or other HVAC&R equipment discussed above. For example, the present techniques may be incorporated with any HVAC&R system having an economizer, such as the intermediate vessel 70, and a compressor, such as the compressor 32. The discussion below describes the present techniques incorporated with embodiments of the compressor 32 configured as a compact dual stage compressor 32. However, it should be noted that the systems described herein may be incorporated with other embodiments of the compressor 32, such as a single stage compressor, a compact triple stage compressor or a multistage compressor with any number of suitable compressor stages (e.g., four stages, five stages, six stages, eight stages, etc.).

[0039] As mentioned above, the present disclosure is directed to a compact hydraulic VGD regulation system for regulating compressor capacity (e.g., multistage centrifugal compressor capacity). The compact hydraulic VGD regulation system may include one or more hydraulic VGD actuators each operating a respective VGD component associated with a respective diffuser passage of a stage of the multistage centrifugal compressor (e.g., compressor 32). Each of the embodiments illustrated in the aforementioned figures may include a VGD regulation system in accordance with present embodiments. In particular, the compact hydraulic VGD regulation system enables hydraulic actuators to control a position of a respective VGD component of a respective stage of the multistage centrifugal compressor. In addition, the compact hydraulic VGD regulation system may enable maintaining a desired length (e.g., compactness) of each stage, and thus maintaining a relatively compact (e.g., substantially short) overall shaft length. Furthermore, the compact hydraulic VGD regulation system may enable operation of the VGD actuators and VGD components via a load compensation system (e.g., an unequal load compensation system) to efficiently control a position of the VGD component. In some embodiments, the compact hydraulic VGD regulation system may additionally reduce misalignment of the VGD component within the compressor (e.g., within the diffuser passage). Therefore, the compact hydraulic VGD regulation system may reduce flow inefficiencies and increase confidence of an expected control of the position of the VGD component(s). In addition,the compact hydraulic VGD regulation system may reduce hydraulic fluid leakages, which may increase efficient control of a position of the VGD component, and thus increases an overall efficiency of the compressor.

[0040] FIG. 5 is a cross-sectional side view of an embodiment of a portion of the compressor 32 of the HVAC&R system 10 having a compact hydraulic VGD regulation system 100. As discussed herein, in some embodiments, the compressor 32 may be a single-stage or multistage compact centrifugal compressor 32. FIG. 5 illustrates an embodiment of a single-stage compact centrifugal compressor 32. The compressor 32 may include a housing 102 and a shaft 104 extending through the housing 102. The compressor 32 may also include one or more compressor stages 106 arranged consecutively along an axis 108 (e.g., a rotational axis of the shaft 104) of the compressor 32, with respect to a longitudinal axis 110. In the illustrated embodiment, the compressor 32 includes a first compressor stage 116. To facilitate discussion, the HVAC&R system 10 and its respective components may be described with reference to the longitudinal axis 110, a vertical axis 112, which is oriented relative to a direction of gravity, and a lateral axis 114. Furthermore, each stage of the one or more compressor stages 106 may include a respective inlet, impeller, outlet, and a diffuser passage. For instance, the first compressor stage 116 includes an impeller 118, a suction inlet 120, an impeller outlet 126, and a diffuser passage 124. The impeller 118 may be coupled to the shaft 104, such as via one or more fasteners.

[0041] During operation of the compressor 32, the shaft 104 may rotate (e.g., via operation of the motor 50) and cause rotation of the impeller 118. Rotation of the impeller 118 may draw a working fluid (e.g., refrigerant) into the housing 102 via the suction inlet 120 and toward the impeller 118, and drive the working fluid to flow along a working fluid flow path 122 (e.g., from the evaporator 38, from the intermediate vessel 70) through the compressor 32. The impeller 118 may impart mechanical energy onto the working fluid and discharge the working fluid towards the diffuser passage 124 of the compressor stage 116 of the compressor 32 via the impeller exit or outlet 126 of the impeller 118. In particular, the diffuser passage 124 may be defined by and extending between two sides(e.g., walls, edges, a portion of the housing 102, compressor casing) of the diffuser passage 124. For example, the diffuser passage 124 may be defined by a nozzle base plate 128 (e.g., compressor casing, housing 102) and a compressor discharge plate 130 (e.g., diffuser plate) of the compressor housing 102. The working fluid may be directed through a diffuser inlet 132 of the diffuser passage 124, which is positioned at a downstream end of the diffuser passage 124 relative to a working fluid flow direction through the diffuser passage 124. Additionally, the working fluid may be directed from the diffuser passage 124 to a volute 134 of the compressor 32. The working fluid may be directed from the volute 134 to a condenser (e.g., the condenser 34) for heat exchange with a fluid, such as a cooling fluid.

[0042] In some embodiments, during operation, a velocity of the working fluid entering the compressor 32 (e.g., from the evaporator 38, from the intermediate vessel 70) and / or a velocity of the working fluid exiting the impeller 118 may vary. For example, during low capacity and / or partial load conditions. In some instances, the velocity of the working fluid may be relatively low (e.g., low capacity operation, low working fluid velocity operations, low compressor speed operations). In addition, the impeller 118 may not impart sufficient energy to the working fluid to enable the working fluid to traverse a length 136 (e.g., radial distance value) of the diffuser passage 124 to reach the volute 134. As such, the compressor 32 may experience a stall and / or a surge due to a low volume and / or an inconsistent or unstable flow of the working fluid through the diffuser passage 124. Accordingly, as discussed herein the compressor 32 may include the compact hydraulic VGD regulation system 100. The compact hydraulic VGD regulation system 100 may be configured to adjust a respective volume of the diffuser passage inlet 132 to provide consistent and stable flow of the working fluid through the diffuser passage. Thus, the compressor 32, having the compact hydraulic VGD regulation system 100, may operate more efficiently and provide improved performance across a wider range of operational conditions (e.g., low capacity operation, low working fluid velocity operations, low compressor speed operations, partial load conditions), even in situations where the velocity and / or volume of the working fluid may vary and / or be relatively low.

[0043] It should be appreciated, that even though the present disclosure illustrates a single stage centrifugal compressor, in some embodiments, the compact hydraulic VGD regulation system may be included in a centrifugal compressor with a greater number of compressor stages (e.g., two stage, three stages, five stages, eight stages, multistage, etc.).

[0044] With reference to FIG. 5, the compact hydraulic VGD regulation system 100 may include a hydraulic VGD ring assembly 138 coupled to a hydraulic actuator assembly 140 (e.g., hydraulic motor, hydraulic piston). In some embodiments, the hydraulic VGD ring assembly 138 may be disposed within the nozzle base plate 128 (e.g., a portion of the housing 102, compressor casing) of the compressor 32. In addition, in some embodiments, the hydraulic VGD ring assembly 138 may be disposed at (e.g., near, adjacent, next to) the diffuser inlet 132. In some embodiments, a component (e.g., VGD ring) of the hydraulic VGD ring assembly 138 may form (e.g., be incorporated with) a portion of the nozzle base plate 128 (e.g., wall, edge, a portion of the compressor housing 102) at the diffuser inlet 132. In particular, the component may, in a fully retracted position (e.g., not extended into the diffuser inlet 132) be positioned within a recess 152 (e.g., a gap, a hole, an opening, a cavity) within the nozzle base plate 128. During operation, a component of the hydraulic VGD ring assembly 138 may extend into the diffuser inlet 132. For example, the component of the hydraulic VGD ring assembly may extend from a recess in the nozzle base plate 128 and into the diffuser inlet 132 (e.g., extend / move toward the discharge plate 130). It should be appreciated, that in some embodiments, the hydraulic VGD ring assembly 138 may be disposed within the discharge plate 130, and the component of the hydraulic VGD ring assembly 138 may extend from the discharge plate 130 and into the diffuser inlet 132 (e.g., extend / move toward the nozzle base plate 128).

[0045] The hydraulic actuator assembly 140 may be disposed exterior to and / or on an exterior surface of the compressor casing 102. Furthermore, the hydraulic actuator assembly 140 may be fluidly coupled to the hydraulic VGD ring assembly 138 via one or more fluid lines 142 (e.g., piping, tubes, channels). In particular, hydraulic components of the hydraulic actuator assembly 140 may be fluidly coupled to hydraulic components ofthe hydraulic VGD ring assembly 138. Thus, actuation of components (e.g., hydraulic components) of the hydraulic actuator assembly 140 may cause similar actuation of components (e.g., hydraulic components) of the hydraulic VGD ring assembly 138. Therefore, actuation of the hydraulic actuator assembly 140 may be configured to control (e g., adjust) a flow of working fluid through the compressor 32 (e.g., via through a respective diffuser passage). The fluid lines 142 may be configured to contain a hydraulic fluid (e.g., oil, incompressible fluid) that may flow between the hydraulic actuator assembly 140 and the hydraulic VGD ring assembly 138. As further discussed herein, the compact hydraulic VGD regulation system 100 may be configured to operate via a load compensation system. In other words, the compact hydraulic VGD regulation system 100 may contain a fix volume of hydraulic fluid between the hydraulic VGD ring assembly 138 and the hydraulic actuator assembly 140. As such, a first displacement of the hydraulic fluid at the hydraulic actuator assembly 140 may be generally equal to a second displacement of the hydraulic fluid at the hydraulic VGD ring assembly 138.

[0046] To controllably actuate components of the hydraulic motor piston assembly 140, and thus components of the hydraulic VGD ring assembly 138, the HVAC&R system 10 may include a control system 144 (e.g., a controller, an automation controller, an electronic controller, a programmable controller, a VGD controller, a cloud-computing device, control circuitry). The control system 144 may be communicatively coupled to and configured to control (e.g., operate, actuate) the compact hydraulic VGD regulation system 100. For example, the control system 144 may be configured to operate the hydraulic actuator assembly 140. In particular, the control system 144 may operate the hydraulic actuator assembly 140 to cause actuation of components of the hydraulic VGD ring assembly 138. Thus, the control system 144 may control and / or adjust a flow rate (e.g., velocity) of the working fluid through the respective diffuser passage (e.g., the diffuser passage 124). In this way, the control system 144 may enable consistent and stable flow of the working fluid through the one or more diffuser passages to reduce a potential of surge and / or stall conditions and improve performance of the compressor 32 even atvarying operational conditions (e.g., low capacity operation, low working fluid velocity operations, low compressor speed operations, partial load conditions).

[0047] The control system 144 may include a memory 146 and processing circuitry 148 (e g., a microprocessor, processor, processing system). The memory 146 may include volatile memory, such as random-access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, solid-state drives, or any other non-transitory computer-readable medium storing instructions that, when executed, control operation of the compressor 32. The processing circuitry 148 may be configured to execute such instructions. As an example, the processing circuitry 148 may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof.

[0048] The control system 144 may be configured to actuate components of the hydraulic motor piston assembly 140, and thus components of the hydraulic VGD ring assembly 138 based on received sensor data. For example, the HVAC&R system 10 (e.g., vapor compression system 14) may include one or more sensors 150 communicatively coupled to the control system 144. In addition, the control system 144 may actuate components of the hydraulic motor piston assembly 140 based on feedback from a sensor 150. The sensors 150 may be communicatively coupled to the control system 144. As an example, the sensors 150 may monitor one or more operational conditions (e.g., operational parameters, operational values) associated with the HVAC&R system 10 (e.g., the vapor compression system 14). Furthermore, the sensors 150 may transmit sensor data indicative of the one or more operational conditions to the control system 144. The control system 144 may receive the data associated with the one or more operational conditions. The control system 144 may determine a flow condition (e.g., stall condition, surge condition) associated with the compressor 32 based on the one or more operational conditions. It should be appreciated that the control system 144 may determine a potential flow condition (e.g., impending flow condition), such as a potential stall condition or a potential surgecondition, based on the one or more operational conditions. In particular, a potential flow condition may be a predicted future flow condition should the operational state of the compact hydraulic VGD regulation system 100 remain the same. Furthermore, the control system 144 may determine a flow condition based on one or more operational condition values being outside of a range of desired operational condition values. For example, the control system 144 may determine that an operational condition value, received via the one or more sensors 150, is below a threshold value (e.g., threshold operational value, lower limit of the desired range of values). Alternatively, the control system 144 may determine that the operational condition value is above a threshold value (e.g., threshold operational value, upper limit of the desired range of values). In response, the control system 144 may determine a flow condition (e.g., stall condition, surge condition) of the compressor 32 based on the received operational condition value being outside of the desired range of operational condition values. To this end, the control system 144 may operate components of the hydraulic actuator assembly 140 based on the flow condition of the compressor 32.

[0049] Alternatively, in some embodiments, the one or more sensors 150 may be configured to transmit an indication of a flow condition of the compressor 32 to the control system 144. For instance, the sensors 150 may transmit the indication based on a monitored value of an operational condition being detected as outside of a desired range of values. For example, when the one or more sensors 150 detects that an operational condition value is below a threshold value (e.g., lower limit of the desired range of values) and / or detects that an operational condition value is above a threshold value (e.g., upper limit of the desired range of values), the one or more sensors 150 may transmit the indication of a flow condition (e.g., stall condition, surge condition) of the compressor 32 to the control system 144. In either case, as further discussed in more detail below, the control system 144 may be configured to transmit control signals to components of the hydraulic actuator assembly 140 to thus actuate components of the hydraulic VGD ring assembly 138 based on the flow condition of the compressor 32 (e.g., based on the received data and / or indication).

[0050] In some embodiments, the one or more sensors 150 may be temperature sensors configured to detect a temperature associated with the HVAC&R system 10. For example, the one or more sensors 150 may detect a temperature of the working fluid at particular points within the vapor compression system 14 and / or the compressor 32. In particular, the one or more sensors 150 may detect a compressor discharge temperature, an evaporator discharge temperature, an intermediate vessel discharge temperature, and / or a suction inlet temperature. Additionally or alternatively, the one or more sensors 150 may be pressure sensors configured to detect a pressure of the working fluid at particular points within the vapor compression system 14 and / or the compressor 32. For example, the one or more sensors 150 may detect a compressor discharge pressure, an evaporator discharge pressure, an intermediate vessel discharge pressure, and / or a suction inlet pressure.

[0051] FIG. 6 is a perspective view of an embodiment of a hydraulic VGD ring assembly 138 of the compact hydraulic VGD regulation system 100. The hydraulic VGD ring assembly 138 includes a VGD ring 200, one or more VGD pistons 202 (e.g., pins, rods, driven pistons, VGD actuator), and a hydraulic VGD ring housing 204. In some embodiments, each of the one or more VGD pistons may be classified as a hydraulic piston. Furthermore, in some embodiments, each stage of the one or more compressor stages 106 of the compressor 32 may include a hydraulic VGD ring assembly 138 with a VGD ring 200 positioned at a respective inlet to a respective diffuser passage. As discussed herein, the VGD ring 200 may be configured to vary a size (e.g., volume, capacity) of an inlet (e.g., a diffuser gap, diffuser opening) of a diffuser passage by physically extending across and substantially blocking at least a portion of the inlet of the diffuser passage. For example, the VGD ring 200 may be configured to translate (e.g., axially translate) in a first direction 206, with respect to the longitudinal axis 110 (e.g., generally parallel to the axis 108) to cause the respective inlet of the diffuser passage to decrease in size (e.g., volume). In addition, the VGD ring 200 may be configured to translate in a second direction 208 (e.g., a direction generally opposite the first direction 206) with respect to the longitudinal axis 110, to cause the respective inlet of the diffuser passage to increase in size (e.g., volume).

[0052] In other words, a range of translational positions of the VGD ring 200 may be from a first translational position (e.g., a retracted position) in which the VGD ring 200 is completely out of the diffuser inlet enabling a largest possible (with respect to range of system configurations) space (e.g., gap, volume) of the diffuser inlet, to a second translational position (e.g., an extended position) in which the VGD ring 200 occupies a portion of a volume of the diffuser inlet enabling a smallest possible (with respect to range of system configurations) space (e.g., gap, volume) of the diffuser inlet. In this way, an axial position of the VGD ring 200 may correlate with a size of a respective diffuser inlet of the diffuser passage. As discussed herein, during operation, the compact hydraulic VGD regulation system 100 may controllably increase or decrease a flow rate (e.g., velocity) of the working fluid through the diffuser passage and / or reduce back flow of the working fluid during low speed and / or low capacity operations by adjusting the respective axial positions of the one or more VGD rings 200. It should be understood that the retracted position and the extended position of each VGD ring 200 is described relative to the respective diffuser inlet in which the VGD ring 200 is disposed. In some embodiments, a VGD ring 200 in a retracted position may occupy a portion of a volume of the respective diffuser inlet enabling a smallest possible (with respect to range of system configurations) space (e.g., gap, volume) of the diffuser inlet, and the VGD ring 200 in an extended position may be completely out of the respective diffuser inlet enabling a largest possible (with respect to range of system configurations) space (e.g., gap, volume) of the diffuser inlet.

[0053] Furthermore, the hydraulic VGD ring assembly 138 may include the one or more VGD pistons 202 each coupled to the VGD ring 200. The one or more VGD pistons 202 may be configured to translate in the first and / or second directions 206, 208 to cause the VGD ring 200 to axially translate in the first and / or second directions 206, 208. In the illustrated embodiment, the hydraulic VGD ring assembly 138 includes three VGD pistons 202, a first, second, and third VGD piston 210, 212, 214 coupled to the VGD ring 200. In particular, the VGD ring 200 may be coupled at a respective first end of each of the first, second, third VGD pistons 210, 212, 214. In some embodiments, the one or more VGD pistons 202 may be positioned at substantially equivalent angles about a circumference 216of the VGD ring 200. For example, as in the illustrated embodiment, the VGD ring 200 includes three VGD pistons 202 positioned (e.g., approximately positioned) at 120-degree angles about the VGD ring 200. In another embodiment, the VGD ring 200 may include four VGD pistons 202 positioned (e.g., approximately positioned) at 90-degree angles about the VGD ring 200. It should be appreciated that, in some embodiments, the hydraulic VGD ring assembly 138 may include any suitable number of VGD pistons 202 (e.g., 2, 5, 8, 10) at any suitable angular position relative to one another and / or about the VGD ring 200 to enable efficient translational movement of the VGD ring 200 via translation of the VGD pistons 202. Also, while certain directions are referenced and illustrated, present embodiments may actuate the VGD ring 200 in any appropriate direction to achieved desired functionality based on relative positioning of system components.

[0054] As discussed herein, the control system 144 may be communicatively coupled to and configured to operate the hydraulic actuator assembly 140 to cause the hydraulic actuator assembly 140 to actuate components of the hydraulic VGD ring assembly 138. In particular, as discussed herein, hydraulic components of the hydraulic actuator assembly 140 may be fluidly coupled to hydraulic components of the hydraulic VGD ring assembly 138, such as the VGD pistons 202. In this way, actuation of components of the hydraulic actuator assembly 140 may cause similar actuation of the VGD pistons 202. As such, controlling actuation of components of the hydraulic actuator assembly 140, via the control system 144, may control (e g., actuate, operate, regulate) a position of the VGD ring 200, and thus control and / or adjust a flow rate (e.g., velocity) of the working fluid through the respective diffuser passage (e.g., the diffuser passage 124). In particular, the control system 144 may be configured to enable adjustment of a position (e.g., an axial position) of the VGD ring 200 relative to the axis 108 and / or relative to the housing 102.

[0055] By way of example, the control system 144 may be configured to instruct components of the hydraulic actuator assembly 140 to cause actuation of the hydraulic components. Furthermore, actuation of the hydraulic components of the hydraulic actuator assembly 140 may cause similar actuation (e.g., due to fluid connectivity between eachother) of the respective VGD pistons 202. In turn, actuation (e.g., translation with respect to the axis 108, in the first direction 206 or second direction 208) of the VGD pistons 202 causes translation of the corresponding (e.g., coupled) VGD ring 200 relative to the axis 108. In other words, actuation of hydraulic components of the hydraulic actuator assembly 140 may be transformed to a translational force to translate (e.g., adjust, move) the VGD ring 200 relative to the axis 108 (e.g., in the first direction 206 and / or the second direction 208).

[0056] FIG. 7 is a cross-sectional perspective view of a portion of an embodiment of the hydraulic VGD ring assembly 138. During operation, a portion of the hydraulic VGD piston 202 may be contained within (e.g., extend within) the hydraulic VGD ring housing 204, while an additional portion of the hydraulic VGD piston 202 may extend external to the hydraulic VGD ring housing 204. In particular, the hydraulic VGD piston 202 may couple to the VGD ring 200 at a first end 300. In addition, the hydraulic VGD piston 202 may be disposed within the hydraulic VGD ring housing 204 at a second end 302 opposite of the first end 300. In the illustrated embodiment, the VGD piston 202 includes a VGD piston chamber 306. In particular, components of the VGD piston 202 may be disposed (e.g., positioned) within a VGD piston chamber 306. The VGD piston chamber 306 may be a chamber (e.g., void, gap, cavity, slot, compartment) formed by and / or within the hydraulic VGD ring housing 204. In addition, the VGD piston 202 may include a VGD piston rod 308 (e.g., pin, shaft, bar) coupled to and / or integrated with a VGD piston head 310. The VGD piston head 310 may be disposed or positioned within (e.g., configured to translate within) the VGD piston chamber 306. The VGD piston rod 308 may be coupled to the VGD piston head 310 at a first end and coupled to the VGD ring 200 (e.g., to a VGD piston base, via one or more fasteners 324) at a second end opposite the VGD piston head 310. In the illustrated embodiment, the VGD piston rod 308 may extend through the VGD piston chamber 306, through a VGD piston channel 328, and be configured to couple to the VGD ring 200 via a VGD piston base 312. The VGD piston channel 328 may include one or more seals 330 configured to block a flow of fluid and / or prevent leakage of fluid from the VGD piston chamber 306. In addition, the VGD piston base 312 may be coupledto the VGD ring 200 via one or more fasteners 326 (not shown in FIG. 7). The VGD piston base 312 may also be coupled to the VGD piston rod 308 via the one or more fasteners 324. As such, translation of the VGD piston 202 in the first and / or second directions 206, 208, may be transformed into an approximately equal translation of the VGD ring 200 in the first and / or second directions 206, 208.

[0057] The diameter of the VGD piston head 310 may be greater than a diameter of the VGD piston rod. In addition, the diameter of the VGD piston head 310 may be similar in diameter as a diameter of the VGD piston chamber 306. Furthermore, the VGD piston head 310 may include one or more seals 330 disposed on an exterior surface 332 of the VGD piston head 310 and configured to block a flow of fluid and / or prevent leakage of fluid across and / or around the VGD piston head 310. In addition, the one or more seals 330 may interface (e.g., sealingly interface) with an interior surface 334 of the VGD piston chamber 306. In some embodiments, the hydraulic VGD ring assembly 138 may include one or more gasket components (e.g., bellows, flexible gaskets, seals, not shown in FIG. 7) configured to block a flow of fluid and / or prevent leakage of fluid across and / or around each respective VGD piston head 310. For example, each VGD piston 202 may be associated with two gasket components, each positioned on a side of the respective VGD piston head 310.

[0058] To this end, the VGD piston chamber 306 may be fluidly divided (e.g., partitioned, sectioned) by the VGD piston head 310 into a first portion 316 (e.g., extend portion) and a second portion 318 (e.g., retract portion). Each of the first and second portions 314, 316 may be fluidly coupled to the hydraulic actuator assembly 140. For example, in the illustrated embodiments, the first portion 316 includes a first port 320 (e.g., extend port, extend flow port) and the second portion 318 includes a second port 322 (e.g., retract port, retract flow port). As such, the first portion 316 may receive a flow of fluid (e.g., from the hydraulic actuator assembly 140) or discharge a flow of fluid (e g., to the hydraulic actuator assembly 140) via the first port 320. Similarly, the second portion 318 may receive a flow of fluid (e.g., from the hydraulic actuator assembly 140) and dischargea flow of fluid (e.g., to the hydraulic actuator assembly 140) via the second port 322. The first and second ports 320, 322 may be fluidly coupled to the hydraulic actuator assembly 140. In addition, the first and second ports 320, 322 may receive and / or discharge a flow of hydraulic fluid via the one or more fluid lines 142. During operation, a flow of hydraulic fluid (e.g., incompressible fluid) received via the first port 320 and into the first portion 316 of the VGD piston chamber 306 may cause a force to be exerted on the VGD piston head 310 in the first direction 206. As a result, the VGD piston 202, and thus the VGD ring 200, may translate (e.g., extend) in the first direction 206. In addition, a flow of hydraulic fluid (e.g., incompressible fluid) received via the second port 322 and into the second portion 318 of the VGD piston chamber 306 may cause a force to be exerted on the VGD piston head 310 in the second direction 208. As a result, the VGD piston 202, and thus the VGD ring 200, may translate (e.g., retract) in the second direction 208.

[0059] FIG. 8 is a perspective view of an embodiment of the hydraulic actuator assembly 140 of the compact hydraulic VGD regulation system 100. As discussed herein, the hydraulic actuator assembly 140 is fluidly coupled, via one or more fluid lines 142, to the hydraulic VGD ring assembly 138. In particular, the hydraulic actuator assembly 140 is configured to actuate the VGD pistons 202 (e.g., via a flow of flow within the one or more fluid lines 142), and thus the VGD ring 200 of the hydraulic VGD ring assembly 138. The hydraulic actuator assembly 140 may include an actuator 400 (e.g., motor), an actuator shaft 402 (e.g., rod, pin, arm), an actuator block 404 (e.g., coupler), and a hydraulic piston assembly 406. The actuator 400 may be communicatively coupled to the control system 144, and configured to actuate (e.g., translate) the actuator shaft 402 in the first direction 408 (e.g., extend direction) and the second direction 410 (e.g., retract direction). In addition, the actuator shaft 402 may be coupled to and / or be integrated with the actuator block 404. As such, translation of the actuator shaft 402 in the first direction 408 causes the actuator block 404 to actuate in the first direction 408. In addition, translation of the actuator shaft 402 in the second direction 410 causes the actuator block 404 to actuate in the second direction 410. Furthermore, as discussed in more detail below, actuator block 404 may be coupled to one or more components of the hydraulic piston assembly 406 andcause the components of the hydraulic piston assembly 406 to actuate in a similar (e.g., same) direction (e.g., either the first direction 208 or the second direction 410) as the actuator block 404.

[0060] FIG. 9 is a cross-sectional perspective view of an embodiment of the hydraulic actuator assembly 140 illustrated in FIG. 8. In particular, internal components contained within a housing 420 of the hydraulic piston assembly 406 are illustrated. For example, the hydraulic piston assembly 406 may include one or more pistons 412 (e.g., driving pistons, actuator, hydraulic piston). Each of the one or more pistons 412 may be classified as a hydraulic piston. Furthermore, each of the one or more pistons 412 may be coupled to the actuator block 404. In addition, each of the one or more pistons 412 may include a respective piston chamber 414. In particular, components of each of the one or more pistons 412 may be positioned (e.g., contained) within each respective piston chamber 414. Furthermore, each of the piston chambers 414 may be a chamber (e.g., void, gap, cavity, slot, compartment) formed by and / or within the housing 420. Each piston 412 may include a piston head 416 coupled to and / or integrated with a piston rod 418 (e.g., pin, shaft, bar). In particular, a portion of each piston 412 may be contained within (e.g., extend within) the housing 420 of the hydraulic piston assembly 406, while an additional portion of each piston 412 may extend external to the housing 420 and couple to the actuator block 404. For example, in the illustrated embodiment, each of the pistons 412 (e.g., the piston head 416) may be disposed or positioned within (e.g., configured to translate within) the piston chamber 414 at a first end 422 and coupled to (e.g., via the piston rod 418) the actuator block 404 (e.g., via one or more fasteners) at a second end 424 opposite the first end 422.

[0061] In the illustrated embodiment, each piston rod 418 may extend through a respective piston chamber 414, and through a respective piston channel 426. Each piston channel 426 may be formed within the housing 420 and extending from the respective piston chamber 414 to an exterior surface 450 of the housing 420. Each of the piston rods 418 are further configured to couple to the actuator block 404. Each piston channel 426 may additionally include one or more seals (not shown in FIG. 9) configured to block aflow of fluid (e.g., hydraulic fluid) and / or prevent leakage of fluid from the respective piston chamber 414. As such, translation of the actuator block 404 (e.g., via the actuator 400) in the first direction 408 may cause translation of each piston 412 in the first direction 408, and translation of the actuator block 404 in the second direction 410 may cause translation of each piston 412 in the second direction 410.

[0062] A diameter of each piston head 416 may be greater than a diameter of each respective piston rod 418. In addition, the diameter of the piston head 416 may be similar in diameter as a diameter the piston chamber 414. Furthermore, in some embodiments, each of the piston heads 416 may include one or more seals (not shown in FIG. 9) disposed on an exterior surface 452 of the respective piston head 416. The one or more seals may be configured to block a flow of fluid and / or prevent leakage of fluid across and / or around each respective piston head 416. In addition, the one or more seals may interface (e.g., sealingly interface) with an interior surface 454 of the piston chamber 404. In some embodiments, as illustrated in FIG. 9, the hydraulic piston assembly 406 may include one or more gasket components 428 (e.g., bellows, bellow gaskets, flexible gaskets) configured to block a flow of fluid and / or prevent leakage of fluid across and / or around each respective piston head 416. As illustrated, each piston 412 may be associated with two gasket components, each positioned on a side of the respective piston head 416.

[0063] Furthermore, each piston chamber 414 may be fluidly divided (e.g., partitioned, sectioned) by the respective piston head 416 into a first portion 430 (e.g., retract portion) and a second portion 432 (e.g., extend portion). Each of the first and second portions 430, 432 may be fluidly coupled to the hydraulic VGD ring assembly 138. For example, in the illustrated embodiments, the first portion 430 includes a first port 434 (e.g., retract port, retract flow port). In addition, the second portion 432 includes a second port 436 (e.g., extend port, extend flow port). As such, during operation, the piston 412 may translate in the first direction 408 causing the first portion 430 to decrease in volume, and thus the first portion 430 of the piston chamber 414 discharges a flow of fluid (e.g., to the hydraulic VGD ring assembly 138) via the first port 434. Furthermore, the second portion 432 mayincrease in volume, and thus the second portion 432 of the piston chamber 414 receives (e.g., draws) a flow of fluid (e.g., from the hydraulic VGD ring assembly 138) via the second port 436. In addition, the piston 412 may translate in the second direction 410 causing the second portion 432 to decrease in volume, and thus the second portion 432 of the piston chamber 414 discharges a flow of fluid (e.g., to the hydraulic VGD ring assembly 138) via the second port 436. In addition, the first portion 430 may increase in volume, and thus the first portion 430 of the piston chamber 414 receives (e.g., draws) a flow of fluid (e.g., from the hydraulic VGD ring assembly 138) via the first port 434. The first and second ports 434, 436 may be fluidly coupled to the hydraulic VGD ring assembly 138, and discharge and / or receive a flow of hydraulic fluid via the one or more fluid lines 142.

[0064] FIG. 10 is a perspective view of an embodiment of a hydraulic actuator assembly 140 of the compact hydraulic VGD regulation system 100 with cross-sectional views of options for the piston housing 420. In particular, components and features of the illustrated embodiment may be similar to those described with respect to FIGS. 8 and 9. As illustrated, the hydraulic piston assembly 406 includes three pistons 412 (e.g., within three separate piston chambers 414) positioned adjacent to each other (e.g., with respect to the lateral axis 114) and arranged in an equilateral triangle design (e.g., shape, arrangement). It should be appreciated that the hydraulic piston assembly 406 may include any suitable number of pistons 412 (e.g., 4, 5, 6, 10) arranged in any suitable shape and / or geometry with relation to each other, such that a single actuator (e.g., actuator 400 coupled to an actuator block 404) may be coupled to and configured to actuate (e.g., translate, displace, shift) each of the pistons 412 by a same (e.g., approximately equal) amount of displacement (e g., distance). For example, in some embodiments, the hydraulic piston assembly 406 may include four pistons, each coupled to a single actuator block, and arranged in a diamond or square shape with respect to each other. As other examples, in some embodiments, pistons may be arranged linearly adjacent to each other (e.g., side-by-side), staggered (e.g., zig-zag), and / or offset with respect to each other. Each arrangement 440, 442, 444 are cross-sectional front views of example embodiments of the housing 420 withvarious configurations of the pistons 412 and / or piston chambers 414 within the hydraulic piston assembly 406.

[0065] Furthermore, FIG. 11 is a cross-section perspective view of an embodiment of a hydraulic actuator assembly 140 of the compact hydraulic VGD regulation system 100. In particular, components and features of the illustrated embodiment may be similar to those described with respect to FIGS. 8-10. In addition, the hydraulic motor assembly 140 may include three pistons heads 416 (e.g., each within three separate piston chambers 414) each coupled consecutively along a length 438 of a single piston rod 418. As illustrated, the piston heads 416 may be positioned adjacent to each other with respect to (e.g., with respect to the longitudinal axis 110) and / or arranged end-to-end in a linear configuration. It should be appreciated that the hydraulic piston assembly 406 may include any suitable number of piston heads 416 (e.g., 4, 5, 6, 10) arranged consecutively in a line along the length of the piston rod 418, such that actuation (e.g., translation) of the actuator block 404 may cause a same (e.g., approximately equal) amount of displacement (e.g., distance) of each of the piston heads 416 within the respective piston chamber 414. As in FIGS. 9 and 10, each piston chamber may be fluidly coupled to the hydraulic VGD ring assembly 138 via two respective ports. As illustrated, each piston chamber includes the first port 434 and the second port 436 fluidly coupled to the hydraulic VGD ring assembly 138 via the one or more fluid lines 142.

[0066] The present embodiments of the compact hydraulic VGD regulation system 100 may reduce misalignment (e.g., tilting) of the VGD ring 200 within the respective diffuser inlet 132. Thus, the compact hydraulic VGD regulation system 100 may reduce instability or inconsistency of flow (e.g., air flow, fluid flow) within the compressor 32. In particular, as described in more detail below, the compact hydraulic VGD regulation system 100 may enable operation via a load compensation system (e.g., an unequal load compensation system) to efficiently control a position of the VGD ring 200. Each VGD piston chamber 306 (e.g., each respective VGD piston 202 disposed therein) of the hydraulic VGD ring assembly 138 may be fluidly coupled to (e.g., paired with) a respective piston chamber 414(e.g., each respective piston 412 disposed therein) of the hydraulic actuator assembly 140. Therefore, in some embodiments, a number of piston chambers 306 (e.g., VGD pistons 202)may be equal to a number of piston chambers 414 (e.g., pistons 412).

[0067] Furthermore, to enable approximately equal displacement of the VGD ring 200, with respect to the longitudinal axis 110 and / or the axis 108 of FIG. 5 (e.g., as felt by each respective VGD piston 202 coupled to the VGD ring 200), a size and / or shape (e.g., volume) of each VGD piston chamber 306 (e g., associated with actuating a particular VGD ring 200) may be approximately equal with respect to each other. In addition, a size and / or shape (e g., volume) of each piston chamber 414 (e.g., fluidly coupled to its respective VGD piston chamber 306) may be approximately equal with respect to each other. In this way, a volume of fluid (e.g., hydraulic fluid) transferring between each piston chamber 414 and the respective VGD piston chamber 306 fluidly coupled thereto may be substantially equal. In other words, a first volume of fluid transferred between a first piston chamber 414 and a respective first VGD piston chamber 306 may be substantially equal to an additional volume of fluid (e.g., a second volume, a third volume, etc.) transferred between an additional piston chamber 414 and its respective additional VGD piston chamber 306. To this end, when actuated by the hydraulic actuator assembly 140, each VGD piston 202 (e.g., piston rod 308, piston head 310) may be displaced (e.g., moved, translated) an approximately equal amount (e.g., distance) with respect to each other. It should be appreciated, that in some embodiments, the VGD piston chambers 306 and each piston chamber 414 may be of any suitable size and / or shape that enables each VGD piston 202 to be displaced (e.g., translated, moved) an approximately equal amount (e.g., distance). In this way, the VGD ring 200 may be actuated (e.g., translated) while maintaining an aligned position (e.g., generally parallel with the vertical axis 112).

[0068] With the foregoing in mind, FIG. 12 is a schematic diagram of an embodiment of the compact hydraulic VGD regulation system 100. In particular, components and features of the illustrated embodiment may be similar to those described with respect to FIGS. 5-11. In addition, FIG. 12 illustrates an embodiment of the load compensationsystem of the compact hydraulic VGD regulation system 100. In particular, the illustrated compact hydraulic VGD regulation system 100 includes a first, second, and third VGD piston 500, 502, 504 coupled to a VGD ring 200. Each of the first, second, and third VGD piston 500, 502, 504 may be fluidly coupled to a respective first, second, and third piston 506, 508, 510. In addition, each of the first, second, and third piston 506, 508, 510 are couple to the actuator block 404. The actuator block 404 may be coupled to and actuated by the actuator 400 via the actuator shaft 402. As in the illustrated embodiment, the first portion 430 of the piston chamber 414 of the first piston 506 is fluidly coupled (e.g., via a fluid line 142) to the second portion 318 of the VGD piston chamber 306 of the first VGD piston 500. In addition, the second portion 432 of the piston chamber 414 is fluidly coupled (e.g., via a fluid line 142) to the first portion 316 of the VGD piston chamber 306. As discussed herein, a fixed volume of fluid may be contained within the first portion 430, the second portion 316, and the fluid line 142 coupling them to each other. Furthermore, a fixed volume of fluid may be contained within the second portion 432, the first portion 318, and the fluid line 142 coupling them to each other. Both the second piston 508 and the third piston 510 are fluidly coupled to the second VGD piston 502 and the third VGD piston 504, respectively, in a similar way as described for the first piston 506 and the first VGD piston 500. In addition, a size (e.g., volume) of each of the piston chambers 414 associated with the first, second, third pistons 506, 508, 510 are approximately (e.g., substantially) equal to each other. In a similar way, a size (e.g., volume) of each of the VGD piston chambers 306 associated with the first, second, third VGD pistons 500, 502, 504 are approximately equal to each other.

[0069] As such, actuation (e.g., translation) of the actuator block 404 (e.g., via the actuator 400) in a first direction 512 may cause an approximately equal volume of fluid within each of the piston chambers 414 associated with the first, second, third pistons 506, 508, 510 to discharge from the respective first portions 430. In other words, actuation (e.g., translation) of the actuator block 404 (e.g., via the actuator 400) in the first direction 512 may cause a first portion of a first fixed volume of fluid to flow from the first piston chamber 506 toward the first VGD piston 500, a second portion of a second fixed volumeof fluid to flow from the second piston chamber 508 toward the second VGD piston 502, and a third portion of a third fixed volume of fluid to flow from the third piston chamber 510 toward the third VGD piston 504, wherein the first portion, the second portion, and the third portion each comprise a respective volume of fluid that is substantially equivalent. The discharged volume of fluid may then be received via the respective second portions 318 of the VGD piston chambers 306 associated with each of the first, second, third VGD pistons 202. At approximately the same time, an approximately equal volume of fluid is discharged from each of the respective first portions 316 of the first, second, third, VGD pistons 202 and received (e.g., drawn) into each of the respective second portions 432 of the piston chambers 414 associated with the first, second, third pistons 506, 508, 510. As a result, each of the first, second, third, VGD pistons 202 are actuated (e.g., translated, displaced) approximately (e.g., substantially) the same amount (e.g., same distance, equal amount), and thus the VGD ring 200 is actuated (e.g., extended, translated) in the first direction 512 an equal amount (e.g., equal distance) by each of the first, second, third VGD pistons 202. The load compensation system may operate similarly, but in reverse, to actuate (e.g., retract, translate) the VGD ring 200 in a second direction 514.

[0070] The present disclosure may provide one or more technical effects useful in the operation of an HVAC&R system. For example, present embodiments of the compact hydraulic VGD regulation system having all of the motor pistons (e.g., the pistons 412) being driven by a single actuator (e.g., actuator 400) in combination with each of the motor pistons being fluidly coupled to a corresponding VGD piston (e.g., the VGD pistons 202) may enable efficient control of a position (e.g., movement, actuation, translation, displacement) of the VGD ring (e.g., VGD ring 200), while reducing misalignment of the VGD ring (e.g., slanting, tilting). As such, the present embodiments of the compact hydraulic VGD regulation system may reduce flow inefficiencies and increase confidence of an expected control of the position of the VGD component(s). In addition, during operation associated with a compressor, the compact hydraulic VGD regulation system may improve efficiency and performance of the compressor, even at partial load conditions, by reducing instability or inconsistency of flow within the compressor andpreventing surges and / or stalls. In addition, the compact hydraulic VGD regulation system described herein may enable two or more VGD rings to be independently operated and actuated within respective diffuser inlets (e.g., diffuser passages) of each stage of the compressor, while maintaining a desired length (e.g., compactness) of each stage. Thus, the compact hydraulic VGD regulation system may enable efficient control and / or regulation of a capacity of the compressor while also enabling a relatively compact (e.g., substantially short) overall shaft length (e.g., axial length) of the compressor, thus maintaining stable rotor dynamics, or management of lateral and torsional vibrations of the multistage centrifugal compressor.

[0071] While only certain features and embodiments of the present disclosure 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. It is, therefore, to be noted that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the present disclosure. 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 present disclosure, or those unrelated to enabling the claimed embodiments). 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.

[0072] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve thepresent technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function], ..” or “step for [perform]ing [a function]...”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMS:

1. A heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system, comprising: a vapor compression circuit; and a compressor fluidly coupled to the vapor compression circuit, the compressor comprising: a diffuser passage; and a variable geometry diffuser (VGD) regulation system, comprising: a motor piston coupled to an actuator; a VGD piston fluidly coupled to the motor piston; and a VGD ring disposed at a diffuser inlet of the diffuser passage, wherein the VGD piston is coupled to the VGD ring, and wherein the actuator is configured to control a position of the VGD ring with respect to the diffuser inlet via the motor piston and the VGD piston.

2. The HVAC&R system of claim 1, wherein the motor piston is a first motor piston, the VGD piston is a first VGD piston, and the VGD regulation system comprises: a second motor piston coupled to the actuator; a third motor piston coupled to the actuator; a second VGD piston fluidly coupled to the second motor piston and coupled to the VGD ring; and a third VGD piston fluidly coupled to the third motor piston and coupled to the VGD ring, wherein the actuator is configured to control the position of the VGD ring with respect to the diffuser inlet via the first motor piston, the first VGD piston, the second motor piston, the second VGD piston, the third motor piston, and the third VGD piston.

3. The HVAC&R system of claim 2, wherein:the first motor piston, the second motor piston, and the third motor piston are arranged within a common housing; the first motor piston comprises a first motor piston chamber, the second motor piston comprises a second motor piston chamber, the third motor piston comprises a third motor piston chamber; the first motor piston chamber, the second motor piston chamber, and the third motor piston chamber are formed within the common housing; the first motor piston chamber is configured to contain a first volume of fluid, the second motor piston chamber is configured to contain a second volume of fluid, the third motor piston chamber is configured to contain a third volume of fluid; and each of the first volume of fluid, the second volume of fluid, and the third volume of fluid each comprises a respective volume of fluid that is substantially equivalent.

4. The HVAC&R system of claim 3, wherein: the first motor piston comprises a first motor piston rod configured to extend from the first motor piston chamber, through the housing, and to couple to an actuator shaft associated with the actuator; the second motor piston comprises a second motor piston rod configured to extend from the second motor piston chamber, through the housing, and to couple to the actuator shaft; and the third motor piston comprises a third motor piston rod configured to extend from the third motor piston chamber, through the housing, and to couple to the actuator shaft.

5. The HVAC&R system of claim 4, wherein the actuator is configured to actuate each of the first motor piston rod, the second motor piston rod, and the third motor piston rod a substantially equal amount via the actuator shaft.

6. The HVAC&R system of claim 5, the first motor piston rod, the second motor piston rod, and the third motor piston rod are configured to be actuated by theactuator to cause a first portion of the first volume of fluid to flow from the first motor piston chamber toward the first VGD piston, a second portion of the second volume of fluid to flow from the second motor piston chamber toward the second VGD piston, and a third portion of the third volume of fluid to flow from the third motor piston chamber toward the third VGD piston, wherein the first portion, the second portion, and the third portion each comprise a respective volume of fluid that is substantially equivalent.

7. The HVAC&R system of claim 6, wherein each of the first VGD piston, the second VGD piston, and the third VGD piston are configured to actuate the VGD ring to adjust the position of the VGD ring with respect to the diffuser inlet based on the first portion, the second portion, and the third portion received from the respective first motor piston, the second motor piston, and the third motor piston.

8. The HVAC&R system of claim 2, wherein the first VGD piston, the second VGD piston, and the third VGD piston are each coupled to the VGD ring at substantially equivalent angles about a circumference of the VGD ring.

9. The HVAC&R system of claim 8, wherein the first VGD piston, the second VGD piston, and the third VGD piston each comprise a respective VGD piston chamber, wherein each respective VGD piston chamber comprises a volume that is substantially equivalent.

10. The HVAC&R system of claim 2, wherein the first motor piston, the first VGD piston, the second motor piston, the second VGD piston, the third motor piston, and the third VGD piston are each classified as a hydraulic piston.

11. The HVAC&R system of claim 1, wherein the compressor is a centrifugal compressor.

12. A heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system, comprising: a vapor compression circuit configured to circulate working fluid therein; and a compressor of the vapor compression circuit, wherein the compressor is configured to compress a flow of the working fluid, the compressor comprising: a diffuser inlet of a diffuser passage configured to receive the flow of the working fluid; and a variable geometry diffuser (VGD) regulation system configured to adjust a volume of the flow of the working fluid through the diffuser inlet, the VGD regulation system comprising: a first motor piston, a second motor piston, and a third motor piston coupled to an actuator; a first VGD piston fluidly coupled to the first motor piston, a second VGD piston fluidly coupled to the second motor piston, and a third VGD piston fluidly coupled to the third motor piston, wherein actuation of the first motor piston, the second motor piston, and the third motor piston, via the actuator, is configured to cause actuation of the first VGD piston, the second VGD piston, and the third VGD piston; and a VGD ring disposed at the diffuser inlet, wherein the first VGD piston, the second VGD piston, and the third VGD piston are coupled to the VGD ring; and a controller communicatively coupled to the actuator, wherein the controller is configured to control the volume of the flow of the working fluid through the diffuser inlet by adjusting a position of the VGD ring with respect to the diffuser inlet via the actuator.

13. The HVAC&R system of claim 12, wherein each of the first motor piston, the second motor piston, and the third motor piston respectively comprise one or more bellow gaskets.

14. The HVAC&R system of claim 12, wherein the controller is configured to: receive an indication of an operational condition associated with theHVAC&R system; and instruct the actuator to control the position of the VGD ring with respect to the diffuser inlet based on the operational condition.

15. The HVAC&R system of claim 14, wherein the operational condition comprises a flow condition associated with the compressor, and wherein the operational condition is configured to indicate an operational value being above a first threshold operational value or being below a second threshold operational value.

16. The HVAC&R system of claim 15, wherein the operational condition is associated with a stall condition or a surge condition associated with the compressor.

17. A heating, ventilation, air conditioning, and / or refrigeration (HVAC&R) system, comprising: a vapor compression circuit; a compressor fluidly coupled to the vapor compression circuit, the compressor comprising a diffuser inlet of a diffuser passage; and a variable geometry diffuser (VGD) regulation system associated with the compressor, comprising: an actuator; a first motor piston coupled to the actuator and fluidly coupled to a first VGD piston; a second motor piston coupled to the actuator and fluidly coupled to a second VGD piston; a third motor piston coupled to the actuator and fluidly coupled to a third VGD piston; anda VGD ring disposed at the diffuser inlet, wherein the first motor piston, the second motor piston, and the third motor piston are configured to cause actuation, via the actuator, of the VGD ring via the first VGD piston, the second VGD piston, and the third VGD piston.

18. The HVAC&R system of claim 17, wherein the VGD ring is coupled to the first VGD piston, the second VGD piston, and the third VGD piston, and wherein the VGD ring is configured to extend into and retract from the diffuser inlet to adjust a size of the diffuser inlet.

19. The HVAC&R system of claim 18, comprising a controller communicatively coupled to the actuator, the controller configured to: receive an operational condition value associated with the HVAC&R system; determine a potential stall condition or a potential surge condition associated with the compressor based on the operational value; and instruct the actuator to cause the first motor piston, the second motor piston, and the third motor piston to actuate the VGD ring to adjust the size of the diffuser inlet based on the potential stall condition or the potential surge condition.

20. The HVAC&R system of claim 17, wherein each of the first motor piston, the second motor piston, and the third motor piston are configured to actuate, via the actuator, the VGD ring to adjust a position of the VGD ring with respect to the diffuser inlet based on a respective volume of fluid that is substantially equivalent being transferred between each of the first motor piston and the first VGD piston, the second motor piston and the second VGD piston, and the third motor piston and the third VGD piston.

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