EP4705634A1

EP4705634A1 - Lubricant pump system for hvac&r system

Info

Publication number: EP4705634A1
Application number: EP24725156.4A
Authority: EP
Inventors: Lars Skovlund Andersen; Christian Per Bunde-Pedersen; Thomas Svejgaard BLOCH; Olav AABO
Original assignee: Tyco Fire and Security GmbH
Current assignee: Tyco Fire and Security GmbH
Priority date: 2023-05-08
Filing date: 2024-05-08
Publication date: 2026-03-11
Also published as: WO2024231431A1

Abstract

A pump for a lubricant return system includes a housing defining an inlet, an outer conduit coupled to the housing and defining a working chamber of the pump, a plunger disposed within the outer conduit and configured to translate within the outer conduit in a first direction and a second direction, opposite the first direction, and a piston pipe disposed within the outer conduit and coupled to the plunger. The pump further includes a first solenoid configured to draw the plunger and the piston pipe in the first direction, a second solenoid configured to draw the plunger and the piston pipe in the second direction, and a plurality of valves configured to transition between respective open positions and respective closed positions in response to movement of the plunger and the piston pipe in the first direction and in the second direction, where movement of the plunger and piston pipe is configured to direct lubricant from the inlet of the pump to an outlet of the pump.

Description

LUBRICANT PUMP SYSTEM FOR HVAC&R SYSTEM

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S. Provisional Application No. 63/464,872, entitled "LUBRICANT PUMP SYSTEM FOR HVAC&R SYSTEM," filed May 8, 2023, which is herein incorporated by reference in its entirety for all purposes.

BACKGROUND

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.

Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, or vapor compression systems, are utilized in residential, commercial, and industrial environments to control environmental properties, such as temperature and humidity, of a conditioned space. The HVAC&R system circulates a working fluid (e.g., refrigerant), which changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures associated with operation of the HVAC&R system. For example, the HVAC&R system utilizes one or more compressors to circulate the working fluid to a heat exchanger (e.g., evaporator, condenser) which may transfer heat between the working fluid and another fluid (e.g., cooling fluid) flowing through the heat exchanger. The one or more compressors may also circulate oil to enable efficient operation of the compressors. The HVAC&R system may include one or more compressors configured to pressurize the working fluid through a working fluid circuit. In many applications, a lubricant, such as oil, may be utilized to lubricate components within the compressor. Unfortunately, lubricant within the compressor may be transferred to one or more of the components within the HVAC&R system (e.g., a heat exchanger), thereby reducing an efficiency and/or a useful life of components of the HVAC&R system.

SUMMARY

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.

In an embodiment, a pump for a lubricant return system includes a housing defining an inlet, an outer conduit coupled to the housing and defining a working chamber of the pump, a plunger disposed within the outer conduit and configured to translate within the outer conduit in a first direction and a second direction, opposite the first direction, and a piston pipe disposed within the outer conduit and coupled to the plunger. The pump further includes a first solenoid configured to draw the plunger and the piston pipe in the first direction, a second solenoid configured to draw the plunger and the piston pipe in the second direction, and a plurality of valves configured to transition between respective open positions and respective closed positions in response to movement of the plunger and the piston pipe in the first direction and in the second direction, where movement of the plunger and piston pipe is configured to direct lubricant from the inlet of the pump to an outlet of the pump.

In another embodiment, a lubricant pump system includes a chamber configured to fluidly couple to a heat exchanger and configured to receive lubricant and/or a mixture of lubricant and working fluid from the heat exchanger and a pump configured to fluidly couple to the chamber via a conduit and configured to operate to remove the lubricant and/or the mixture of lubricant and working fluid from the heat exchanger. The pump includes a plunger and a piston pipe coupled to one another and configured to translate within an outer conduit of the pump in a first direction and in a second direction to direct the lubricant and/or the mixture of lubricant and working fluid from an inlet of the pump to an outlet of the pump, a first solenoid configured to bias the plunger and the piston pipe in the first direction, a second solenoid configured to bias the plunger and the piston pipe in the second direction, and a plurality of valves configured to transition between respective open positions and respective closed positions in response to translation of the plunger and the piston pipe in the first direction and the second direction. The lubricant pump system further includes a controller communicatively coupled to the first solenoid and the second solenoid, and the controller is configured to activate the first solenoid to bias the plunger and the piston pipe in the first direction, and activate the second solenoid to bias the plunger and the piston pipe in the second direction.

In another embodiment, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a vapor compression circuit having a compressor configured to circulate the working fluid through the vapor compression circuit and a heat exchanger configured to place the working fluid in a heat exchange relationship with an additional fluid. The HVAC&R system further includes a lubricant return system configured to remove lubricant from the heat exchanger and return the lubricant to the compressor. The lubricant return system includes a reservoir fluidly coupled to the heat exchanger and configured to receive the lubricant from the heat exchanger, a pump fluidly coupled to the reservoir, where the pump includes a first solenoid and a second solenoid, and where the pump is configured to continuously alternate between a pump stroke and a reset stroke to direct the lubricant out of the heat exchanger, and a controller communicatively coupled to the pump and configured to alternate energization of the first solenoid and the second solenoid to transition the pump between the pump stroke and the reset stroke.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 is a perspective view of an embodiment of a building that may utilize a heating, ventilating, air conditioning, and/or refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure; FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

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

FIG. 4 is a cross-sectional view of an embodiment of a heat exchanger and a lubricant pump system, in accordance with an aspect of the present disclosure;

FIG. 5 is a cross-sectional view of an embodiment of a lubricant pump system, in accordance with an aspect of the present disclosure;

FIG. 6 is a cross-sectional side view of an embodiment of a pump of a lubricant pump system during a pump/fill stroke, in accordance with an aspect of the present disclosure;

FIG. 7 is a cross-sectional side view of an embodiment of a pump of a lubricant pump system during a reset stroke, in accordance with an aspect of the present disclosure;

FIG. 8 is a cross-sectional side view of an embodiment of a plurality of valves of the lubricant pump system of FIG. 5 during a pump/fill stroke, in accordance with an aspect of the present disclosure;

FIG. 9 is a cross-sectional side view of an embodiment of a plurality of valves of the lubricant pump system of FIG. 5 during a reset stroke, in accordance with an aspect of the present disclosure;

FIG. 10 is a perspective view of an embodiment of a plunger and a piston pipe of a lubricant pump system, in accordance with an aspect of the present disclosure;

FIG. 11 is a perspective view of an embodiment of a check valve of a lubricant pump system, in accordance with an aspect of the present disclosure; and

FIG. 12 is a perspective view of an embodiment of a check valve of a lubricant pump system, in accordance with an aspect of the present disclosure. DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may 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.

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.

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) 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" to another feature, "generally perpendicular" 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 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.

As briefly discussed above, a heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system may be configured to operate to satisfy heating and/or cooling demands within a building, home, or other conditioned space. For example, the HVAC&R system may include a vapor compression system (e.g., chiller system, heat pump system) that transfers thermal energy between a working fluid (e.g., refrigerant, ammonia) and a fluid to be conditioned (e.g., air, water, brine). The vapor compression system may include one or more vapor compression circuits (e.g., heat pumps) that each include a condenser and an evaporator that are fluidly coupled to one another via one or more conduits (e.g., vapor compression circuit, working fluid circuit, refrigeration circuit). Further, each vapor compression circuit may include a compressor configured to pressurize and circulate the working fluid through the conduit and, thus, enable the transfer of thermal energy between the working fluid and the fluid to be conditioned via the condenser and/or the evaporator.

In certain vapor compression systems, a lubricant (e.g., oil) may be directed through the compressor to lubricate components thereof. As the vapor compression system operates, the lubricant may mix with working fluid directed through the compressor, and the lubricant and working fluid mixture may then be directed to heat exchangers of the vapor compression system. However, introduction of lubricant into the heat exchangers of the vapor compression system may limit a heat exchange efficiency of the heat exchanger and/or cause wear and degradation to components of the heat exchanger. Thus, traditional systems may employ systems to remove lubricant from the heat exchangers and/or from other portions of the vapor compression system. For example, traditional systems may include a reservoir associated with each heat exchanger, and the reservoir may be configured to collect lubricant within the heat exchanger. Once the lubricant is collected, traditional lubricant pumps may operate to direct all or substantially all of the lubricant within the reservoir back to the compressor. However, returning an amount of lubricant to the compressor that exceeds a threshold volume may be detrimental to compressor operation. Additionally, traditional systems do not account for the potential of liquid working fluid mixed with the lubricant collected by the reservoir. That is, traditional systems may return a lubricant and working fluid mixture to the compressor, which includes liquid working fluid, and the liquid working fluid may decrease an efficiency of the compressor and/or increase wear and degradation to components of the compressor.

Accordingly, embodiments of the present disclosure are directed toward a lubricant pump system that operates (e.g., continuously operates) to remove a reduced (e.g., limited, controlled) amount of lubricant from a heat exchanger relative to traditional systems. For example, present embodiments are directed to a lubricant pump system having a first solenoid and a second solenoid configured to bias a plunger and piston pipe in opposite directions, thereby causing a small volume of lubricant to be pumped by the lubricant pump system. As the plunger and piston pipe is biased in one of two directions by the first and/or second solenoid, various check valves within the lubricant pump system may transition between open and closed positions, thereby enabling lubricant to flow through the lubricant pump system. In this way, a small volume of lubricant (e.g., less than a threshold volume of lubricant) may be continuously removed from a heat exchanger by the lubricant pump system, and the small volume of lubricant may be directed toward the suction side of the compressor. By limiting the volume of lubricant pumped during a single stroke of the lubricant pump system (e.g., at a particular instance in time), efficiency of the vapor compression system may be increased as the compressor is not flooded with the lubricant removed from the heat exchanger.

Additionally, present embodiments are directed to a lubricant pump system that may operate in a conditioning and boil off mode to separate liquid working fluid from the lubricant before directing the lubricant back to the compressor. For example, upon determining that an amount of liquid working fluid within the lubricant is greater than a threshold amount, the lubricant pump system may activate both the first and second solenoid to increase a temperature of the lubricant and working fluid mixture within the lubricant pump system. As the temperature increases, liquid working fluid within the lubricant may be heated into a vaporized working fluid to separate the working fluid from the lubricant. Thereafter, the lubricant may be directed to the compressor. In this way, an amount of liquid working fluid introduced into the suction side of the compressor may be reduced and/or blocked, thereby limiting wear and degradation on the compressor and increasing the operating efficiency of the compressor.

Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning, and 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., chiller system, heat pump system) 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 may 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 may include air handlers 22 and/or other components that may be shared between or among floors. Further, the HVAC&R system 10 may be implemented to provide conditioning (e.g., refrigeration) in other applications, such as food and beverage refrigeration, industrial process refrigeration, and so forth. Indeed, it should be appreciated that the disclosed systems and methods may be utilized with any suitable HVAC&R system 10 that operates with a working fluid (e.g., refrigerant, heat transfer fluid) and a lubricant (e.g., oil).

FIGS. 2 and 3 are embodiments of the vapor compression system 14 that may be used in the HVAC&R system 10. The vapor compression system 14 may circulate a working fluid through a circuit starting with a compressor 32. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38. The vapor compression system 14 may further include a control panel 40 that has an analog to digital (A/D) converter 42, a microprocessor 44, a non-volatile memory 46, and/or an interface board 48. Some examples of fluids that may be used as working fluids in the vapor compression system 14 are "natural" working fluids like ammonia (NH₃) (e.g., R- 717), water vapor (e.g., R-718), hydrofluorocarbon (HFC) based working fluids, for example, R-410A, R-407, R-134a, hydrofluoro olefin (HFO), carbon dioxide (CO2) (e.g., R-744), or hydrocarbon based working fluids, or any other suitable working fluid.

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

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, a screw compressor, a scroll compressor, or a reciprocating 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 to a working fluid liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The liquid working fluid 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.

The liquid working fluid 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 working fluid in the evaporator 38 may undergo a phase change from the 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 a cooling load 62. The cooling fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, a condensing working fluid from a cascade system, 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 working fluid. 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 working fluid exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

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 be incorporated with any HVAC&R system having an evaporator, such as the evaporator 38. The discussion below describes the present techniques incorporated with embodiments of the evaporator 38 configured as a shell and plate evaporator. However, it should be noted that the systems and methods described herein may be incorporated with other embodiments of the evaporator 38 and HVAC&R system 10. Further, the present techniques may be incorporated with HVAC&R systems that utilize any suitable working fluid, such as ammonia (NH₃), as a working fluid (e.g., refrigerant).

As noted above, during operation of a compressor, lubricant may escape from components of the compressor and may mix with the working fluid (e.g., working fluid) directed through the compressor and may therefore be circulated with the working fluid through the vapor compression system and components thereof. For example, as a vapor compression system operates, lubricant mixed with the working fluid may accumulate in one or more of the heat exchangers (e.g., condenser 34, evaporator 38) of the vapor compression system, thereby decreasing a heat exchange efficiency of the heat exchanger. Accordingly, certain heat exchangers may utilize a lubricant pump system to more desirably remove lubricant from the heat exchanger and deliver the lubricant back to the compressor, thereby enabling more efficient operation of the HVAC&R system. In accordance with present techniques, the lubricant pump system may remove lubricant from the heat exchanger and return the lubricant to the compressor in a steadier (e.g., more consistent, more controlled, more continuous) manner than traditional systems. Further, the disclosed embodiments may be implemented at reduced costs and with reduced complexity, thereby reducing overall costs associated with HVAC&R system 10 manufacturing, operation, maintenance, and so forth.

FIG. 4 is a cross-sectional view of a lubricant pump system 100 (e.g., oil pump return system) configured to remove lubricant (e.g., oil) from a heat exchanger, such as the evaporator 38, of the vapor compression system 14. In the present embodiment, the evaporator 38 may include a housing 70 and a shell 72 disposed within the housing 70. The shell 72 may define an interior volume 74 of the evaporator 38, and one or more heat exchange components (e.g., heat exchange plates, heat exchange tubes, heat exchange coils) may be positioned within the interior volume 74 to exchange heat between a cooling fluid (e.g., water) directed through the one or more heat exchanger components and a working fluid 76 (e.g., ammonia, refrigerant) directed across the one or more heat exchange components. For example, the evaporator 38 may be a flooded evaporator in which the working fluid 76 may be directed into the interior volume 74 and across the one or more heat exchange components such that the working fluid 76 absorbs heat from the cooling fluid directed through the one or more heat exchange components before the cooling fluid is directed to a cooling load. It should be appreciated that the lubricant pump system 100 discussed herein may be utilized with other types of heat exchanges (e.g., condensers, flooded heat exchangers, shell and tube heat exchangers, shell and plate heat exchangers, and the like) without departing from the scope of this disclosure.

As noted above, in certain embodiments, the working fluid 76 directed into the evaporator 38 may be mixed with lubricant that has escaped from a compressor (or other component) of the vapor compression system 14. However, certain properties of the working fluid 76 (e.g., surface tension, adhesion, viscosity, etc.) may enable the lubricant to be separated (e.g., via gravity) from the working fluid 76. For example, a density of the working fluid 76 may be less than a density of the lubricant mixed within the working fluid 76, such that the lubricant may separate from the working fluid 76 and travel in a direction 78 (e.g., via gravity) along a vertical axis 80 of the evaporator 38 toward a base of the evaporator 38 adjacent which the lubricant pump system 100 is positioned. In certain embodiments, as the lubricant travels in the direction 78 toward the base of the evaporator 38, the lubricant may collect and/or accumulate in a section 86 (e.g., lower section, bottom section) of the shell 72 before being discharged from the shell 72 and directed toward the lubricant pump system 100. For example, the lubricant pump system 100 may include a chamber 102 (e.g., reservoir) configured to collect lubricant and/or a mixture of the lubricant and the working fluid 76 from the evaporator 38. The chamber 102 may be in fluid communication with a conduit 104 configured to direct the lubricant and/or mixture of lubricant and working fluid 76 towards a pump 106 of the lubricant pump system 100. For example, the conduit 104 may be in fluid communication with the pump 106, and a valve 108 may be configured to control a flow of lubricant into the pump 106, as described in greater detail below.

In certain embodiments, a reservoir 88 (e.g., pan, drip tray, basin, container) may be disposed and/or positioned beneath the evaporator 38 relative to gravity. As the evaporator 38 operates, the working fluid 76 may absorb heat from the cooling fluid directed through heat exchange components of the evaporator 38. As the working fluid 76 absorbs heat from the cooling fluid, the cooling fluid may condense and condensate particles (e.g., droplets, moisture) may form on an exterior of the shell 72 or the housing 70. In turn, as the condensate particles accumulate, the condensate particles may fall from the shell 72 or the housing 70 of the evaporator 38 and may be collected by the reservoir 88 before being directed away from the evaporator 38.

FIG. 5 is a cross-sectional view of an embodiment of the lubricant pump system 100. As noted above, the lubricant oil pump system 100 may include the chamber 102 configured to collect lubricant and/or a mixture of lubricant and working fluid 76 from the evaporator 38. The chamber 102 may be fluidly coupled to the conduit 104, and the conduit 104 may direct lubricant collected by the chamber 102 toward the pump 106. In certain embodiments, the valve 108 may regulate the flow of lubricant toward the pump 106. For example, during operation of the lubricant pump system 100, the valve 108 may be adjusted to an open position (e.g., via a controller), thereby enabling lubricant from the chamber 102 to be directed into the pump 106. When the pump 106 is inoperative (e.g., during an off-cycle of the HVAC&R system 10, during maintenance or replacement), the valve 108 may be adjusted to a closed position, thereby blocking lubricant from being directed toward the pump 106. In some embodiments, the gaseous working fluid 76 may be separated from the lubricant in the chamber 102. For example, as lubricant is directed from the chamber 102, through the conduit 104, and toward the pump 106, gaseous working fluid 76 (e.g., gaseous ammonia) may be directed in an opposite direction through the conduit 104 and toward the chamber 102. To this end, a working fluid return conduit 101 is fluidly coupled to the chamber 102 and may direct the gaseous working fluid 76 toward a suction side of a compressor, thereby enabling the working fluid 76 to be recirculated into the compressor.

The pump 106 may be configured to operate (e.g., continuously operate) to remove lubricant from the evaporator 38 (e.g., the chamber 102). As illustrated in FIG. 5, the pump 106 includes a housing 110 (e.g., fitting, connector), an inlet 112, and an outlet 114. The pump 106 further includes an outer conduit 116 (e.g., outer can pipe) coupled to the housing 110 that defines an interior volume 118 (e.g., working chamber) of the pump 106. The outer conduit 116 may be formed from stainless steel or any other suitable material (e.g., nonferromagnetic material). A plunger 120 is disposed within the interior volume 118 of the outer conduit 116, and the plunger 120 may be coupled to a piston pipe 122 (e.g., inner conduit), such as via a threaded connection. For example, the piston pipe 122 may include a threaded portion configured to interact with threads formed in a first end 121 of the plunger 120 (e.g., upstream end of the plunger 120 relative to a flow direction of lubricant through the pump 106). The pump 106 may also include a first solenoid 124 (e.g., lower solenoid, bottom solenoid) and a second solenoid 126 (e.g., upper solenoid, top solenoid) configured to bias (e.g., force, draw) the plunger 120 and piston pipe 122 in a particular direction. For example, the plunger 120 may be composed of material with magnetic properties that enable the plunger 120 to be attracted toward the first or second solenoid 124, 126 in response to energization (e.g., activation) of either the first solenoid 124 or the second solenoid 126.

During a pump/fill stroke, the second solenoid 126 may be energized, thereby causing the plunger 120 and piston pipe 122 to move or translate within the outer conduit 116 in a first direction 128 toward the second solenoid 126. During a reset stroke (e.g., plunger repositioning stroke, liquid rearrangement stroke), the second solenoid 126 may be deactivated and the first solenoid 124 may be energized, thereby causing the plunger 120 and piston pipe 122 to move or translate within the outer conduit 116 in a second direction 130 toward the first solenoid 124. Each of the plunger 120 and the piston pipe 122 may be generally hollow or annular pipes, thereby enabling a flow of lubricant therethrough, as described in greater detail below. Furthermore, the plunger 120 and the piston pipe 122 may be made of different materials. For example, as noted above, the plunger 120 may include a material with magnetic properties, thereby enabling the plunger 120 to be biased in different directions via activation of the solenoids 124, 126. In contrast, the piston pipe 122 may be formed from a metallic material having substantially no magnetic properties, thereby limiting (e.g., blocking) the piston pipe 122 from being biased and/or manipulated in a particular direction by activation of the solenoids 124, 126. Instead, the piston pipe 122 translates through the interior volume 118 of the pump 106 based on movement of the plunger 120 coupled to the piston pipe 122.

The pump 106 may include a strainer 132 positioned proximate the inlet 112. The strainer 132 is configured to filter lubricant directed through the inlet 112 and into the pump 106. For example, the strainer 132 may be formed from a wire mesh material, thereby enabling the strainer 132 to block debris and/or other particles from entering into the pump 106. An insert 134 may also be disposed within the housing 110 and proximate the inlet 112. The insert 134 may include a hollow central passage that enables lubricant to flow therethrough. The strainer 132 may be coupled to the insert 134, and the insert 134 may be coupled fluidly coupled to the piston pipe 122, thereby enabling a flow of lubricant from the inlet 112 to a central passage within the piston pipe 122 and the plunger 120, as described in greater detail below. In certain embodiments, the insert 134 may couple (e.g., press fit) to the outer conduit 116 or to the piston pipe 122.

As illustrated in FIG. 5, a first check valve 136 is positioned within the insert 134 and may be configured to regulate the flow of lubricant from the inlet 112 into the pump 106. Additionally, a piston check valve 138 may be positioned downstream of the first check valve 136 relative to a flow direction 142 of lubricant through the pump 106. In certain embodiments, a second check valve 140 may be positioned downstream of both the first check valve 136 and the piston check valve 138 relative to the flow direction 142 of lubricant through the pump 106. As discussed in greater detail below, each of the valves (e.g., 134, 136, 140) may be biased toward an open or closed position based on a particular operation of the pump 106 (e.g., operating in a pump/fill stroke or reset stroke). For example, during a reset stroke, each of the first and second check valves 136, 140 may be biased or forced to an open position and the piston check valve 138 may be biased or forced to a closed position. During a pump/fill stroke, each of the first and second check valves 136, 140 may be biased or forced to a closed position and the piston check valve 138 may be biased or forced to an open position, as described in greater detail below. In this way, the pump 106 may direct lubricant from the evaporator 38 toward the suction side of a compressor, such that the lubricant may be returned to the compressor to lubricate the components of the compressor.

In certain embodiments, the pump system 100 and/or various components thereof may be communicatively coupled to a control system 150 (e.g., controller) configured to control operation of the pump system 100. For example, the control system 150 may include processing circuitry 152 and a memory 154 (e.g., memory device) configured to store instructions that, when executed by the processing circuitry 152, cause the processing circuitry 152 to energize and/or activate (e.g., cyclically activate) the first solenoid 124, the second solenoid 126, and/or both the first and second solenoids 124, 126, based on a mode of operation of the pump system 100 (e.g., normal mode in which the pump 106 cycles between a pump/fill stroke and a reset stroke, conditioning and boil off mode). Additionally, in certain embodiments, the control system 150 may be configured to control a position of the valve 108 based on the operating mode of the pump 106 (e.g., based on an operating mode of the HVAC&R system 10). For example, upon determining that the pump 106 is inoperative (e.g., during an off-cycle of the HVAC&R system, during maintenance or replacement), the controller 150 may transition the valve 108 toward a closed position, thereby blocking lubricant from being directed toward the pump 106. Upon determining that the pump 106 is operative (e.g., during an on-cycle of the HVAC&R system 10, during an operative mode of the HVAC&R system 10), the controller 150 may transition the valve 108 toward an open position, thereby enabling lubricant from the chamber 102 to be directed into the pump 106.

In certain embodiments, the control system 150 may receive sensor data from a sensor 156 disposed within the pump 106. The sensor 156 may be configured to monitor one or more properties (e.g., temperature, pressure, composition) of the lubricant and/or mixture of lubricant and working fluid 76 directed through the pump 106, thereby enabling the control system 150 to operate the pump system 100 in a desired mode. For example, the sensor 156 may measure or detect a temperature of the lubricant and/or mixture of the lubricant and working fluid 76 at the outlet 114 and communicate data indicative of the temperature to the control system 150. The control system 150 may then determine that a difference between the temperature of the lubricant and/or mixture of lubricant and working fluid 76 and a saturation temperature of the evaporator 38 is less than a threshold amount. A temperature differential between the temperature of the mixture of lubricant and working fluid 76 and the saturation temperature of the evaporator that is less than the threshold amount may be indicative of an undesirable amount (e.g., greater than a threshold amount) of working fluid 76 within the mixture of lubricant and working fluid 76. Thus, in response to a determination that the difference between the temperature of the lubricant and/or mixture of lubricant and working fluid 76 and the saturation temperature of the evaporator is less than the threshold amount, the control system 150 may determine to operate the pump system 100 in a conditioning and boil off mode in which each of the first solenoid 124 and the second solenoid 126 are energized.

By energizing the first and second solenoids 124, 126, the temperature of the plunger 120 may increase, thereby causing a temperature of the lubricant and/or mixture of lubricant and working fluid 76 within the pump 106 to also increase. In turn, as the temperature of the lubricant and/or mixture of lubricant and working fluid 76 is increased, liquid working fluid 76 within the lubricant and working fluid 76 mixture may be heated into a vaporized working fluid 76, and the vaporized working fluid 76 may be directed out of the pump 106 and toward a suction side of a compressor. Additionally, by increasing the temperature of the lubricant and/or mixture of lubricant and working fluid 76, the viscosity of the lubricant and/or mixture of lubricant and working fluid 76 may decrease, thereby facilitating removal of the lubricant from the evaporator 38 (e.g., pump 106).

In response to a determination that the difference between the temperature of the lubricant and/or lubricant and working fluid 76 mixture and the saturation temperature of the evaporator 38 is greater than the threshold amount, the control system 150 may operate the pump system 100 in a normal mode, whereby the pump 106 alternates between a pump/fill stroke in which the second solenoid 126 is energized and a reset stroke in which the first solenoid 124 is energized to draw the lubricant into the pump 106 and remove the lubricant from the evaporator 38. For example, upon determining that the difference between the temperature of the lubricant and/or lubricant and working fluid 76 mixture is above the threshold value, the control system 150 may determine that less than a threshold amount of liquid working fluid 76 is present within the lubricant and/or lubricant and working fluid 76 mixture, and the control system 150 may therefore operate the pump system 100 in the normal mode (e.g., transitioning between pump/fill stroke and reset stroke). In this way, an amount of liquid working fluid 76 directed to the suction side of the compressor may be reduced, thereby increasing the efficiency of the compressor and limiting wear and degradation on the compressor caused by the introduction of liquid working fluid 76 into the suction side of the compressor.

FIG. 6 is a cross-sectional view of an embodiment of the lubricant pump system 100 during a pump/fill stroke. As illustrated in FIG. 6, during a pump/fill stroke, the second solenoid 126 may be energized (e.g., by the control system 150). Upon energizing the second solenoid 126, the plunger 120 (which includes magnetic properties) may be attracted in the direction 128 toward the second solenoid 126. Because the piston pipe 122 is coupled to the plunger 120, the piston pipe 122 may also move in the direction 128 toward the second solenoid 126. As the plunger 120 and piston pipe 122 travel in the direction 128 toward the second solenoid 126, a size of a volume 160 (e.g., space) between the first check valve 136 and the piston check valve 138 may increase, thereby drawing lubricant into the pump 106 via the inlet 112.

During a pump/fill stroke, each of the first and second check valves 136, 140 may transition toward an open position, thereby enabling a flow of lubricant into the volume 160 downstream of the first check valve 136 and upstream of the piston check valve 138 relative to the flow direction 142 of lubricant through the pump 106. For example, the first check valve 136 may include a ball 162, a seat 164, and a pin 165, and the piston check valve 138 may include a ball 166, a seat 168, and a retainer 170. Similarly, the second check valve 140 may include a ball 172 and a seat 174, and a retainer 175. As the plunger 120 and piston pipe 122 travel in the direction 128 toward the second solenoid 126, a size of the volume 160 downstream of the first check valve 136 and upstream of the piston check valve 138 relative to the flow direction 142 of lubricant through the pump 106 may increase, thereby causing the pressure downstream of the first check valve 136 and upstream of the piston check valve 138 to decrease. As the pressure downstream of the first check valve 136 and upstream of the piston check valve 138 decreases, lubricant within the inlet 112 may cause the ball 162 of the first check valve 136 to disengage from the seat 164, such that the first check valve 136 is adjusted to an open position, thereby enabling a flow of lubricant into the volume 160. In certain embodiments, movement of the ball 162 in the direction 128 may be limited by the pin 165.

Further, as the plunger 120 and piston pipe 122 travel toward the second solenoid 126, the seat 168 of the piston check valve 138 may also travel in the direction 128 toward the second solenoid 126, and the ball 166 may rest against the seat 168, thereby adjusting the piston check valve 138 to a closed position. Additionally, as the plunger 120 and the piston pipe 122 travel in the direction 128 toward the second solenoid 126, a volume downstream of the piston check valve 138 and upstream of the second check valve 140 relative to the flow direction 142 of lubricant through the pump 106 may decrease, thereby causing the pressure within the interior volume 118 to increase. As pressure downstream of the piston check valve 138 and upstream of the second check valve 140 increases, lubricant within the interior volume 118 may cause the ball 172 of the second check valve 140 to disengage from the seat 174, thereby enabling lubricant within the interior volume 118 of the pump 106 to be directed out of the pump 106 via the outlet 114. The retainer 175 may be configured to limit movement of the ball 172 as lubricant is directed across the second check valve 140.

It should be noted that in certain embodiments, the second check valve 140 may be configured to limit an amount of gaseous working fluid 76 and/or lubricant from traveling back into the pump 106. That is, the second check valve 140 may enable flow of lubricant and/or working fluid 76 out of the pump 106 in the flow direction 142 while limiting and/or blocking and an amount of fluid migration in a direction opposite to the flow direction 142 of lubricant through the pump 106. Additionally, it should be appreciated that in certain embodiments, certain components may be omitted without departing from the scope of this disclosure. For example, in certain embodiments, the second check valve 140 may be omitted. However, the pump 106 may nevertheless function as described above, such that during a pump/fil I stroke, the first check valve 136 moves toward an open position and the piston check valve 138 moves toward a closed position.

FIG. 7 is a cross-sectional view of an embodiment of the lubricant pump system 100 during a reset stroke (e.g., plunger repositioning stroke, liquid rearrangement stroke). As illustrated in FIG. 7, during a reset stroke, the first solenoid 124 may be energized by the control system 150 and the second solenoid 126 may be deenergized. Upon energization of the first solenoid 124, the plunger 120 and the piston pipe 122 may travel in the direction 130 toward the first solenoid 124. As the plunger 120 and piston pipe 122 travel in the direction 130 toward the first solenoid 124, each of the first and second check valves 136, 140 may transition toward a closed position. In certain embodiments, the plunger 122 and piston pipe 122 may be limited from traveling in the direction 130 by the pin 165. For example, the control system 150 may determine that the reset stroke is completed upon determining that the piston pipe 122 has reached (e.g., contacted) the pin 165.

During the reset stroke, as the plunger 120 travels in the direction 130 toward the first solenoid 124, the seat 168 of the piston check valve 138 may also travel in the direction 130, and the ball 166 may disengaged from the seat 168. Further, as the plunger 120 and piston pipe 122 travel in the direction 130, the volume 160 downstream of the first check valve 136 and upstream of the piston check valve 138 relative to the flow direction 142 of lubricant through the pump 106 may decrease, thereby causing the pressure downstream of the first check valve 136 and upstream of the piston check valve 138 to increase. As the pressure downstream of the first check valve 136 and upstream of the piston check valve 138 increases in response to the volume 160 decreasing, lubricant within the volume 160 may bias the ball 166 of the piston check valve 138 away from the seat 168. In this way, lubricant within the volume 160 may flow across the piston check valve 138 and into the interior volume 118 of the pump 106. While in the interior volume 118 of the pump 106, the lubricant may flow between the outer conduit 116 and an outer surface of the piston pipe 122 and/or through the central passage of the piston pipe 122 and the plunger 120. For example, each of the components within the interior volume 118 may be in fluid communication with one another such that lubricant within the interior volume 118 may flow around and/or through the piston pipe 122 and/or the plunger 120. In certain embodiments, lubricant directed through the central passage of the piston pipe 122 and the plunger 120 may freely travel toward a downstream side of the plunger 120 relative to the flow direction 142 of lubricant through the pump 106.

Additionally, as the plunger 120 and the piston pipe 122 travel in the direction 130, back pressure on the ball 162 of the first check valve 136 (e.g., pressure created by the volume 160 decreasing and/or pressure created by the plunger 120 and piston pipe 122 moving in the direction 130) may bias the ball 162 of the first check valve 136 toward the seat 164 such that the first check valve 136 is biased to a closed position, thereby limiting a flow of lubricant across the first check valve 136. In certain embodiments, as the plunger 120 and the piston pipe 122 travel in the direction 130 toward the first solenoid 124, the volume of the interior volume 118 may increase, thereby causing the pressure of the interior volume 118 to decrease. As the pressure within the interior volume 118 decreases, the ball 172 of the second check valve 140 may engage with the seat 174, thereby limiting a flow of lubricant across the second check valve 140. As noted above, in certain embodiments, the second check valve 140 may be omitted.

FIG. 8 is a cross-sectional view of an embodiment each of the valves 136, 138, 140 within the pump 106 during a pump stroke. As illustrated in FIG. 8, during a pump/fil I stroke, the ball 162 of the first check valve 136 may disengage from the seat 164, thereby enabling a flow of lubricant into the volume 160 upstream of the piston check valve 138 relative to the flow direction 142 of lubricant through the pump 106. Similarly, the ball 172 of the second check valve 140 may disengage from the seat 174, thereby enabling a flow of lubricant out of the pump 106 via the outlet 114. Conversely, the piston check valve 138 may be biased or forced to a closed position. For example, as the plunger 120 and the piston pipe 122 travel in the direction 128 toward the second solenoid 126, the seat 168 may also travel in the direction 128 such that the seat 168 engages with the ball 166, thereby limiting a flow of lubricant across the piston check valve 138.

FIG. 9 is a cross-sectional view of an embodiment of each of the valves 136, 138, 140 within the pump 106 during a reset stroke. As illustrated in FIG. 9, during a reset stroke, the ball 162 of the first check valve 136 may engage with the seat 164, thereby blocking a flow of lubricant into the volume 160. In certain embodiments, during the reset stroke, the ball 172 of the second check valve 140 may engage with the seat 174, thereby blocking a flow of lubricant out of the pump 106 via the outlet 114. Conversely, the piston check valve 138 may be biased or forced to an open position. For example, as the plunger 120 and the piston pipe 122 travel in the direction 130 toward the first solenoid 124, lubricant within the volume 160 may bias the ball 162 away from the seat 164, thereby enabling a flow of lubricant across the piston check valve 138 and into the interior volume 118 of the pump 106. FIG. 10 is a perspective view of an embodiment of the plunger 120 and piston pipe 122. In certain embodiments, the plunger 120 may be sized based on a circumference of the outer conduit 116. For example, the plunger 120 may be sized such that the plunger 120 is loosely fit into the outer conduit 116, thereby enabling movement of the plunger 120 in response to activation of the solenoids 124, 126. As noted above, the plunger 120 may be formed from a magnetic material that enables the plunger 120 to be biased in various directions in response to activation of the solenoids 124, 126. The plunger 120 may be coupled to the piston pipe 122 via a threaded connection, welding, and/or other fastening technique. The plunger 120 and the piston 122 may each include or define a hollow passage 180 that enables a flow of lubricant therethrough. In certain embodiments, the plunger 120 may also include passages 182 formed therein that enable movement of the plunger 120 and the piston pipe 122 within the outer conduit 116. For example, the passages 182 may enable air, working fluid gas, liquid working fluid, and/or lubricant to travel therethrough such that pressure generated by movement of the plunger 120 and piston pipe 122 through the outer conduit 116 may be dissipated through the passages 182.

FIG. 11 is a perspective view of an embodiment of the second check valve 140. The second check valve 140 includes a housing 184 in which the ball 172, the seat 174, and the retainer 175 are disposed and/or retained. The housing 184 may be formed from aluminum or any other suitable material. The second check valve 140 may be fitted to the outer conduit 116 (e.g., adjacent the outlet 114). In certain embodiments, the sensor 156 may be positioned within the housing 184 of the second check valve 140 to measure various properties of the lubricant directed through the pump 106. For example, the sensor 156 may determine that a percentage of liquid working fluid 76 within the lubricant exceeds a threshold value. In response to such a determination, the control system 150 may operate the pump 106 in a conditioning and boil off mode in which each of the first and second solenoids 124, 126 are activated. In this way, the temperature of the lubricant and/or mixture of lubricant and working fluid 76 may be increased such that liquid working fluid 76 within the lubricant and working fluid 76 mixture is heated into a vaporized working fluid 76.

FIG. 12 is a perspective view of an embodiment of the insert 134 having the first check valve 136. The first check valve 136 includes a housing 186 in which the ball 162, the seat 164, and the pin 165 are disposed and/or retained. The housing 186 may be fastened to the outer conduit 116 (e.g., via a threaded coupling), and the piston pipe 122 may be coupled to the housing 186 via a clearance fit (e.g., adjacent the inlet 112). As noted above, in certain embodiments, the pin 165 may retain the ball 162 within the housing 186 and/or may limit movement of the plunger 120 and the piston pipe 122 in a direction (e.g., direction 130) toward the ball 162 and the seat 164. Additionally, in certain embodiments, the insert 134 may include passages 190 that enable a flow of lubricant from the inlet 112 into the insert 134. The insert 134 may be fluidly coupled to the inlet 112 such that lubricant directed through the inlet 112 may be directed into the insert 134. As the pump 106 cycles between the pump stroke and the fill stroke, lubricant may travel across the first check valve 136, into the volume 160, across the piston check valve 138, into the interior volume 118, across the second check valve 140, and out of the pump 106 via the outlet 140. In certain embodiments, the sensor 156 may be positioned within the insert 134 proximate the first check valve 136 to measure various properties of the lubricant directed through the pump 106

As set forth above, the present disclosure may provide one or more technical effects useful in operating compressors of an HVAC&R system that utilize lubricant to lubricate components thereof. Embodiments of the present disclosure may include a lubricant pump system that continuously pumps lubricant collected by a heat exchanger of the HVAC&R system and returns the lubricant to a suction side of a compressor of the HVAC&R system. In this way, an amount of lubricant within the heat exchangers of the HVAC&R system may be limited or reduced, thereby increasing the operating efficiency and/or heat exchange efficiency of the heat exchangers within the HVAC&R system. Further, by reducing and/or limiting an amount of lubricant within the heat exchangers of an HVAC&R system, wear and degradation may also be reduced, thereby saving costs associated with maintenance, replacement and/or repair of the HVAC&R system.

While only certain features and embodiments of the disclosure have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, including temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the 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, such as those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed disclosure. It should be noted 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.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present 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

LUBRICANT PUMP SYSTEM FOR HVAC&R SYSTEM Claims

1. A pump for a lubricant return system, the pump comprising: a housing defining an inlet of the pump; an outer conduit coupled to the housing, wherein the outer conduit defines a working chamber of the pump; a plunger disposed within the outer conduit and configured to translate within the outer conduit in a first direction and in a second direction, opposite the first direction; a piston pipe disposed within the outer conduit and coupled to the plunger; a first solenoid configured to draw the plunger and the piston pipe in the first direction; a second solenoid configured to draw the plunger and the piston pipe in the second direction; and a plurality of valves configured to transition between respective open positions and respective closed positions in response to movement of the plunger and the piston pipe in the first direction and in the second direction, wherein movement of the plunger and piston pipe is configured to direct lubricant from the inlet of the pump to an outlet of the pump.

2. The pump of claim 1, wherein the plurality of valves comprises: a check valve positioned proximate the inlet of the pump and upstream of the piston pipe and the plunger relative to a flow direction of the lubricant from the inlet to the outlet; and a piston check valve positioned downstream of the check valve and upstream of the piston pipe and the plunger relative to the flow direction of the lubricant from the inlet to the outlet.

3. The pump of claim 2, wherein the check valve and the piston check valve are separated from one another by a space that defines a volume configured to receive the lubricant, wherein the volume is fluidly coupled to the working chamber and is configured to direct the lubricant into the working chamber based on translation of the plunger and the piston pipe within the outer conduit.

4. The pump of claim 3, wherein movement of the piston pipe and the plunger in the first direction causes a size of the volume to increase, and wherein movement of the piston pipe and the plunger in the second direction causes the size of the volume to decrease.

5. The pump of claim 3, wherein the check valve is configured to transition toward a first open position to enable the lubricant to flow into the volume and the piston check valve is configured to transition toward a first closed position to block the lubricant from flowing into the working chamber during translation of the piston pipe and the plunger in the first direction.

6. The pump of claim 5, wherein the check valve is configured to transition toward a second closed position to block the lubricant from flowing into the volume and the piston check valve is configured to transition toward a second open position to enable the lubricant within the volume to flow into the working chamber during translation of the piston pipe and the plunger in the second direction.

7. The pump of claim 6, wherein the check valve comprises a first ball and a first seat, the piston check valve comprises a second ball and a second seat, and the second ball is configured to engage with the second seat to transition the piston check valve to the first closed position in response to movement of the piston pipe and the plunger in the first direction.

8. The pump of claim 7, wherein the first ball is configured to engage with the first seat to transition the check valve to the second closed position in response to movement of the piston pipe and the plunger in the second direction.

9. The pump of one of claims 2 to 8, wherein the check valve is a first check valve, and wherein the plurality of valves comprises a second check valve positioned downstream of the piston pipe and the plunger relative to the flow direction of the lubricant from the inlet to the outlet.

10. The pump of one of claims 1 to 9, comprising a strainer disposed within the housing and positioned proximate the inlet, wherein the strainer is configured to filter the lubricant directed through the inlet and into the pump.

11. The pump of one of claims 1 to 10, wherein the piston pipe is coupled to the plunger via a threaded connection.

12. The pump of one of claims 1 to 11, wherein the plunger comprises a magnetic material.

13. A lubricant pump system, comprising: a chamber configured to fluidly couple to a heat exchanger and configured to receive lubricant and/or a mixture of lubricant and working fluid from the heat exchanger; a pump configured to fluidly couple to the chamber via a conduit and configured to operate to remove the lubricant and/or the mixture of lubricant and working fluid from the heat exchanger, where the pump comprises: a plunger and a piston pipe coupled to one another and configured to translate within an outer conduit of the pump in a first direction and in a second direction to direct the lubricant and/or the mixture of lubricant and working fluid from an inlet of the pump to an outlet of the pump; a first solenoid configured to bias the plunger and the piston pipe in the first direction; a second solenoid configured to bias the plunger and the piston pipe in the second direction; and a plurality of valves configured to transition between respective open positions and respective closed positions in response to translation of the plunger and the piston pipe in the first direction and the second direction; and a controller communicatively coupled to the first solenoid and the second solenoid, wherein the controller is configured to: activate the first solenoid to bias the plunger and the piston pipe in the first direction; and activate the second solenoid to bias the plunger and the piston pipe in the second direction.

14. The lubricant pump system of claim 13, wherein the controller is configured to continuously alternate activation of the first solenoid and the second solenoid to direct the lubricant and/or the mixture of lubricant and working fluid from the inlet of the pump to the outlet of the pump.

15. The lubricant pump system of claim 13 or 14, comprising one or more sensors configured to detect a temperature of the lubricant and/or the mixture of lubricant and working fluid directed through the pump.

16. The lubricant pump system of claim 15, wherein the controller is configured to simultaneously activate the first solenoid and the second solenoid in response to a determination that the temperature of the lubricant and/or the mixture of lubricant and working fluid directed through the pump is greater than a threshold value.

17. The lubricant pump system of one of claims 13 to 16, comprising a working fluid return conduit fluidly coupled to the chamber and configured to direct working fluid toward a suction side of a compressor.

18. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a vapor compression circuit configured to circulate a working fluid therethrough, wherein the vapor compression circuit comprises: a compressor configured to circulate the working fluid; and a heat exchanger configured to place the working fluid in a heat exchange relationship with an additional fluid; and a lubricant return system configured to remove lubricant from the heat exchanger and return the lubricant to the compressor, wherein the lubricant return system comprises: a reservoir fluidly coupled to the heat exchanger and configured to receive the lubricant from the heat exchanger; a pump fluidly coupled to the reservoir, wherein the pump comprises a first solenoid and a second solenoid, and the pump is configured to continuously alternate between a pump stroke and a reset stroke to direct the lubricant out of the heat exchanger; and a controller communicatively coupled to the pump and configured to alternate energization of the first solenoid and the second solenoid to transition the pump between the pump stroke and the reset stroke.

19. The HVAC&R system of claim 18, wherein the pump comprises: a plunger and a piston pipe coupled to one another and configured to move in a first direction during the pump stroke and in a second direction, opposite the first direction, during the reset stroke; and a plurality of valves configured to transition between respective open positions and respective closed positions in response to transition of the pump between the pump stroke and the reset stroke.

20. The HVAC&R system of claim 19, wherein the heat exchanger comprises a flooded evaporator.