COMPRESSOR WITH MULTIPLE LUBRICANT SUMPS

Description

FIELD

This disclosure relates generally to a compressor. More specifically, this disclosure relates to supplying lubricant within a compressor of a heating, ventilation, air conditioning, and refrigeration (HVACR) system.

BACKGROUND

A heating, ventilation, air conditioning, and refrigeration (HVACR) system generally includes a compressor for compressing a working fluid. A compressor can be, for example (but not limited to), a scroll compressor, a rotary compressor, a centrifugal compressor, a reciprocating compressor, or other suitable type of compressor for compressing a working fluid that includes refrigerant (e.g., a single refrigerant or a blend of multiple refrigerants). Such compressors include moving parts, for example, driveshaft, a compression mechanism (e.g., scroll, rotors, impeller, etc.), etc., and one or more bearings for supporting the moving parts. Lubricant is provided to the moving parts, including the bearings, to inhibit wear and prevent damage to the compressor.

In some embodiments, an HVACR system can be a transport climate control system (TCCS) that includes, for example, a transport refrigeration system (TRS) and/or a heating, ventilation, and air conditioning (HVAC) system. A TRS is generally used to control an environmental condition (e.g., temperature, humidity, air quality, and the like) within a cargo space of a transport unit (e.g., a truck, a container (such as a container on a flat car, an intermodal container, etc.), a box car, a semi-tractor, a mass-transit vehicle, or other similar transport unit). The TRS can maintain environmental condition(s) of the cargo space to maintain cargo (e.g., produce, frozen foods, pharmaceuticals, etc.). In some embodiments, the transport unit can include a HVAC system to control a climate within a passenger space of the vehicle. The HVACR system can include a climate control unit attached to the transport unit for housing components of the HVACR system such as, for example, a compressor, at least a portion of a working fluid circuit, one or more fans, etc.

SUMMARY

This disclosure relates generally to a heating, ventilation, air conditioning, and refrigeration (HVACR) system. More specifically, this disclosure relates to providing lubrication to a compressor in a HVACR system.

The embodiments described herein can minimize the total lubricant sump capacity and lubricant carryover over a large mass flow range. That is, the embodiments described herein can prevent a high amount of lubricant carryover for a compressor operating within a large operating envelope and over a wide speed range. In some embodiments, the compressor of the HVACR system can be a horizontal compressor to allow the compressor to be mounted, for example, on a rooftop climate control unit for transport applications.

A horizontal compressor in transport applications, can provide increased flexibility of a climate control unit architecture, particularly for a roof mounted climate control unit. Use of a horizontal compressor can also allow for separate climate control units on the transport unit (e.g., for articulated buses, double decker buses, multi-zone transport refrigeration system for truck or trailer applications, etc.). The embodiments described herein can thereby avoid long suction lines and limit the refrigerant charge amount which can be important for flammable refrigerants such as, but not limited to, A2L, A2, A3, B2L, B2 and B3 refrigerants.

In transport applications, the HVACR system may be required to operate at many different latitudes and climate control within the climate-controlled space may have to provide various climate conditions (e.g., a deep-frozen condition (e.g., about −20° F.), a frozen condition (e.g., about 0° F.), a fresh condition (e.g., about 35° F.)). Accordingly, refrigerant capacity requirements may vary significantly to meet these conditions. The embodiments described herein can allow the HVACR system to operate at these various conditions while providing both low lubricant carryover and use of a small sump. In particular, a compressor of the HVACR system can be a variable speed compressor capable of providing different refrigerant capacities.

The embodiments described herein can provide a lubricant sump placed at an intermediate pressure side of the compressor. An advantage of these embodiments is that a low amount of dissolved refrigerant in the lubricant and a low viscosity can be used (e.g., 20 -120 cSt). Another advantage of these embodiments is that heat from an electric motor may not affect suction gas of the compressor. Also, the lubricant in the lubricant sump can be cooled with an optional lubricant cooler to lower the high discharge temperature and prevent thermal degradation of the lubricant. An active lubricant separator (such as a coalescing type lubricant separation media) can be added into the lubricant sump. The lubricant, after passing through the optional lubricant cooler, can be introduced to a high pressure to medium pressure lubricant sump valve. In this way, the degassing of the lubricant can be prevented from affecting the suction gas flow of the compressor to a significant degree. By reducing the lubricant carry over, there can be less lubricant in circulation that is required to come back during low velocity in suction lines and/or remote evaporators.

Accordingly, many internal parts used in a vertical scroll compressor with a suction sump can be used in a horizontal compressor.

In an embodiment, a compressor includes a compressor housing, a first lubricant sump, a second lubricant sump, a compression mechanism, and a lubricant supply passage. A discharge chamber with a first lubricant sump and an intermediate-pressure chamber with a second lubricant sump are each disposed within the compressor housing. A suction inlet and a discharge outlet are formed in the compressor housing. The compression mechanism is disposed within the compressor housing and is configured to suction working fluid from the suction inlet and discharge working fluid into the discharge chamber. An intermediate injection port formed in the compression mechanism is fluidly connected to the intermediate-pressure chamber. The lubricant supply passage extends from the discharge chamber to the intermediate-pressure chamber, and a lubricant sump valve configured to control a flow of lubricant through the lubricant supply passage from first lubricant sump of the discharge chamber to the second lubricant sump of the intermediate-pressure chamber. The lubricant in the second lubricant sump is supplied to at least the compression mechanism.

In an embodiment, a heating, ventilation, air conditioning, and refrigeration (HVACR) system includes a working fluid circuit. The working fluid circuit includes a compressor, a condenser, an expansion device, and an evaporator, fluidly connected, through which a working fluid flows.

The compressor in the HVACR system can include a compressor housing, a first lubricant sump, a second lubricant sump, a compression mechanism, and a lubricant supply passage. A discharge chamber with a first lubricant sump and an intermediate-pressure chamber with a second lubricant sump are each disposed within the compressor housing. A suction inlet and a discharge outlet are formed in the compressor housing. The compression mechanism is disposed within the compressor housing and is configured to suction working fluid from the suction inlet and discharge working fluid into the discharge chamber. An intermediate injection port formed in the compression mechanism is fluidly connected to the intermediate-pressure chamber. The lubricant supply passage extends from the discharge chamber to the intermediate-pressure chamber, and the lubricant sump valve is configured to control a flow of lubricant through the lubricant supply passage from the first lubricant sump of the discharge chamber to the second lubricant sump of the intermediate-pressure chamber. The lubricant in the second lubricant sump is supplied to at least the compression mechanism.

In an embodiment, a method directed to operating a compressor is provided. The compressor includes a compressor housing, a first lubricant sump, a second lubricant sump, a compression mechanism, and a lubricant supply passage. A discharge chamber with a first lubricant sump and an intermediate-pressure chamber with a second lubricant sump are each disposed within the compressor housing. A suction inlet and a discharge outlet are formed in the compressor housing. The compression mechanism is disposed within the compressor housing and is configured to suction working fluid from the suction inlet and discharge working fluid into the discharge chamber. An intermediate injection port formed in the compression mechanism is fluidly connected to the intermediate-pressure chamber. The lubricant supply passage extends from the discharge chamber to the intermediate-pressure chamber, and the lubricant sump valve is configured to control a flow of lubricant through the lubricant supply passage from the first lubricant sump of the discharge chamber to the second lubricant sump of the intermediate-pressure chamber. The lubricant in the second lubricant sump is supplied to at least the compression mechanism. The method includes detecting the lubricant condition e.g., level, temperature, pressure, and viscosity in the second lubricant sump via the second lubricant sump level sensor and operating the lubricant sump valve so as to adjust the lubricant level in the second lubricant sump.

BRIEF DESCRIPTION OF THE DRAWINGS

References are made to the accompanying drawings that form a part of this disclosure, and which illustrate embodiments in which the systems and methods described in this Specification can be practiced.

FIG. 1 is a schematic diagram of a working fluid circuit, according to an embodiment.

FIG. 2 is a schematic diagram of a compressor, according to an embodiment.

FIG. 3 is a flowchart of a method of operating a compressor, according to an embodiment.

FIG. 4 is a flowchart of a method for controlling the lubricant level in a compressor, according to an embodiment.

Like reference numbers represent like parts throughout.

DETAILED DESCRIPTION

This disclosure relates generally to a heating, ventilation, air conditioning, and refrigeration (HVACR) system. More specifically, this disclosure relates to supplying lubricant within a compressor of a HVACR system. The HVACR system can be operated under any ambient temperature of the globe, and the space conditioned by the HVACR system can be frozen, refrigerated, or heated. The conditioned space can be, but not limited to, an insulated space or enclosed space such as compartments of a vehicle or a train.

Lubricant can be, for example, an oil. In one example of a horizontal scroll compressor, a lubricant sump is provided at a lower portion of the compressor housing, in which the lubricant sump has a defined level to provide a certain amount of lubricant to the compressor. The availability of the lubricant for lubricating the various parts of the scroll compressor, however, can vary depending on different operating conditions. For example, during start-up conditions of the scroll compressor, the moving parts of the compressor, e.g., orbiting scroll, counter weights, or the like, and/or the bearings, e.g., upper bearings, lower bearings, orbiting bearings, thrust bearings, or the like, are initially primed for lubrication. The majority of the lubricant is returned from the moving parts back to the lubricant sump after overcoming certain forces (e.g., gravity, surface tension, etc.). The return flow of lubricant back to the lubricant sump can vary depending on the configuration of a specific compressor (e.g., size/shape of the parts being lubricated, size of the compressor, lubricant separator position, type of lubricant, type of working fluid (e.g., refrigerant), flow paths through the compressor, motor position, etc.). The speed of the compressor can also change the amount of lubricant supplies/utilized. Thus, the amount of lubricant available in the lubricant sump can vary as the lubricant drains down the scroll compressor during start-up operation (e.g., until an equilibrium level of the flow of lubricant in the compressor is established) or when operating the compressor at a variety of different speeds.

During different operating conditions of the compressor (e.g., operating at higher speed vs. operating a lower speed, etc.), the amount of lubricant available in the lubricant sump can vary and, in some instances, the lubricant sump may not contain an amount of lubricant to maintain a desired flow of lubricant that sufficiently lubricates the moving parts of the compressor, which can result in damage to the compressor. For example, a compressor utilizes a lower flow of lubricant while operating at low speed, and during a change of low-speed to high-speed operation of a compressor, a larger amount of lubricant is needed to maintain sufficient lubrication of the moving parts.

Disclosed herein are embodiments of compressors, HVACR systems with a compressor, and methods of operating a compressor that are able to provide multiple lubricant sumps in the compressor so as to provide a buffering capacity of lubricant to the compressor.

FIG. 1 is a schematic diagram of a working fluid circuit 10 of a HVACR system 1, also called a heat transfer circuit, according to an embodiment. The working fluid circuit 10 includes a compressor 12, a condenser 14, an expansion device 16, and an evaporator 18. The components of the working fluid circuit 10 are fluidly connected.

The working fluid circuit 10 of FIG. 1 is an example and can be modified in other embodiments to include additional components. For example, in an embodiment, the working fluid circuit 10 can include other components such as, but not limited to, one or more flow control devices, additional expansion device(s), receiver tank(s), dryer(s), suction-liquid heat exchanger(s), filter(s), or the like. In an embodiment, the working fluid circuit 10 can include an optional valve 20.

The HVACR system 1 is employed to control an environmental condition (e.g., temperature, humidity, air quality, or the like) in a space (generally referred to as a conditioned space). Examples of a conditioned space include, but are not limited to, an enclosed space within residential building (e.g., a home, etc.), a commercial building (e.g., office building, etc.), a vehicle (e.g., mass transport vehicle, truck, van, etc.), a transport unit (e.g., a container (such as a container on a flat car, an intermodal container, shipping container, etc.), a box car, or other similar transport unit).

For example, the HVACR system 1 in an embodiment may be employed in a transport climate control system configured to condition an enclosed space of a transport unit. The HVACR system 1 may be used for a single temperature application or for a multi-temperature application, e.g., multiple climate control zones, for the transport unit. For example, the HVACR system in an embodiment may be employed as a residential or commercial HVACR system configured to condition the interior space of a building.

The compressor 12, condenser 14, expansion device 16, evaporator 18, and economizer 20, are fluidly connected via working fluid lines 24, 26, 28, 30 (30a and 30b), and 32, and optional working fluid lines 34, and 36. In an embodiment, the working fluid lines 24, 26, 28, 30 (30a and 30b), 32, 34, and 36 can alternatively be referred to as the working fluid conduits 24, 26, 28, 30 (30a and 30b), 32, 34, and 36 or the like.

In an embodiment, the working fluid circuit 10 can be configured to be a cooling system (e.g., an air conditioning system, a refrigeration system, a fluid chiller of an HVACR system, etc.) capable of operating in a cooling mode. In an embodiment, the working fluid circuit 10 can be configured to be a heat pump system that can operate in both a cooling mode and a heating/defrost mode. The HVACR system 1 may be configured to operate in a heating mode, a cooling mode, a dehumidification mode, a defrost mode, and/or the like.

The working fluid circuit 10 can operate according to generally known principles. The working fluid circuit 10 can be configured to heat or cool a process fluid (e.g., water, air, etc.). In an embodiment, the working fluid circuit 10 may represent a chiller or the like that cools a process fluid (e.g., water, a glycol-water solution, etc.), and the process fluid is used to cool air supplied to a conditioned space. In an embodiment, the working fluid circuit 10 may represent an air conditioner or heat pump that conditions a process fluid such as air or the like.

During an exemplary operation of the working fluid circuit 10, a working fluid flows into the compressor 12 from the evaporator 18, at a relatively lower pressure in a gaseous state. The working fluid flows into the compressor 12 through a suction inlet 13A of the compressor 12. The compressor 12 compresses the gas from the relatively lower pressure (e.g., suction pressure (P_S)) to a relatively higher-pressure (e.g., discharge pressure (P_D), which also heats the gas. In an embodiment, the compressor 12 is a positive displacement compressor (e.g., a screw compressor, a scroll compressor, a reciprocating compressor, or the like). The relatively higher-pressure working fluid is discharged from a discharge outlet 13B of the compressor 12.

After being compressed, the relatively higher-pressure and relatively higher temperature gas discharged from the compressor 12 flows from the compressor 12 to the condenser 14 through working fluid line 24. In addition to the working fluid flowing through the condenser 14, a first process fluid PF1 (e.g., external air, external water, hot water to be heated, etc.) flows through the condenser 14. The working fluid flows through the condenser 14 and rejects heat to the first process fluid (e.g., water, air, etc.), which cools and condenses the working fluid.

The cooled working fluid, which is now in a liquid form, flows to the expansion device 16 (e.g., via the working fluid line 26). The expansion device 16 allows the working fluid to expand and reduces the pressure of the working fluid. In an embodiment, the expander 16 may be an expansion valve, expansion plate, expansion vessel, orifice, or other such types of expansion mechanisms. It is to be appreciated that the expansion device may be any type of expansion device used in the field for expanding a working fluid to cause the working fluid to decrease in temperature. The expansion device 16 is referred to herein as an “expander”. The gaseous/liquid working fluid has a lower temperature after being expanded by the expander 16.

The working fluid, which can be a mixed liquid and gaseous form, flows from the expander 16 to the evaporator 18 (e.g., via the working fluid line 28) and to the compressor 12 (e.g., via the working fluid line 32). For example, a first portion of the working fluid (e.g., a main/majority portion) flows from the expander 16 to the evaporator 18 and a second portion of the working fluid flows from the expander 16 to the compressor 12. The second portion of the working fluid flows into an intermediate inlet 13C of compressor 12. This second portion of the working fluid can be referred to as intermediate pressure working fluid. The intermediate pressure working fluid injected into the compression mechanism at an intermediate position. In an embodiment, the working fluid circuit 10 may include an economizer (not shown) that is configured to cool the intermediate pressure working fluid using a different portion of the working fluid (e.g., with the first portion of working fluid).

In addition to the working fluid flowing through the evaporator 18, a second process fluid PF2 (e.g., air, water, chiller water, chiller medium, etc.) flows through the evaporator 18. The working fluid that flows through the evaporator 18 absorbs heat from the second process fluid (e.g., water, air, etc.), which heats the working fluid and cools the second process fluid. The heating of the working fluid converts the working fluid into a gaseous form. The gaseous working fluid then returns to the compressor 12 (via the working fluid line 30 (30a and 30b)). The above-described process continues while the working fluid circuit 10 is operating, for example, in a cooling mode (e.g., while the compressor 12 is enabled).

In an embodiment, the working fluid circuit 10 may include an intermediate pressure adjustment valve 20. The adjustment valve 20 can be used to redirect a portion of the intermediate pressure working fluid from the intermediate inlet 13C to the suction inlet 13A of the compressor 10. The amount of the working fluid flowing into an optional working fluid line 36 is controlled by the adjustment valve 20. The working fluid in the working fluid line 30a is mixed with the working fluid in the working fluid line 36 and is supplied to the compressor 12 via the working fluid line 30b. The gaseous portion of the working fluid that flows to the compressor 12 via the working fluid line 30b is at an intermediate pressure between the relatively lower pressure working fluid and the relatively higher pressure working fluid (e.g., a pressure that is between the discharge pressure and the suction pressure).

FIG. 2 is a schematic diagram of a compressor 100, according to an embodiment. For example, the compressor 100 in an embodiment can be the compressor 12 in the working fluid circuit 10 in FIG. 1.

The illustrated compressor 100 is a single-stage compressor. More specifically, the illustrated compressor 100 is a single-stage horizontal compressor with a horizontal or a near horizontal driveshaft. It is to be appreciated that the principles described in this specification are not limited to single-stage horizontal compressors or horizontal compressors, and in other embodiments features discussed herein for the compressor 100 may be applied to multi-stage compressors having two or more compression stages or to vertical compressors that have a vertical or a near vertical driveshaft.

The compressor 100 includes a compressor housing 102. Components of the compressor 100 are disposed within the compressor housing 102. The compressor 100 includes a discharge chamber 104 and an intermediate-pressure chamber 106 disposed within the compressor housing 102. The discharge chamber 104 and the intermediate-pressure chamber 106 are not directly connected. As shown in FIG. 1, The discharge chamber 104 and the intermediate-pressure chamber 106 are separated by a partition 108 that is impermeable to the working fluid and lubricant. The discharge chamber 104 has a first lubricant sump 110, and the intermediate-pressure chamber 106 has a second lubricant sump 112.

The compressor 100 includes a suction inlet 114, an intermediate inlet 116, and a working fluid discharge outlet 118. The specific locations of the suction inlet 114, the intermediate inlet 116, and the discharge outlet 118 with respect to the compressor housing 102 are not particularly limited to the illustrated embodiment and may be different in other embodiments. For example, the suction inlet 114, the intermediate inlet 116, and the working fluid discharge outlet 118 in an embodiment may be the suction inlet 13A, the intermediate inlet 13C, and the discharge outlet 13B of the compressor 12 in FIG. 1.

The suction inlet 114, the intermediate vapor inlet 116, and the working fluid discharge outlet 118 are configured to fluidly connect with external lines, a suction inlet line 114E, an intermediate vapor inlet line 116E, and a working fluid discharge outlet line 118E, respectively. The suction inlet line 114E, intermediate vapor inlet line 116E, and working fluid discharge outlet line 118E can be part of a refrigeration circuit. For example, the suction inlet line 114E can be the working fluid line 30 (30a and 30b) in FIG. 1, the intermediate vapor inlet line 116E can be the working fluid line 32 in FIG. 1, and the working fluid discharge outlet line 118E can be the working fluid line 24 in FIG. 1.

The compressor 100 includes a compression mechanism 120 disposed in the compressor housing 102. The compression mechanism 120 can be any kind of positive displacement compression mechanism suitable for compressing gaseous working fluid (e.g., gaseous refrigerant) in a working fluid circuit (e.g., working fluid circuit 10 in FIG. 1). For example, the compression mechanism in an embodiment may be, but is not limited to, a pair of intermeshed scrolls (e.g., for a scroll compressor), an intermeshed screws (e.g., for a rotary compressor), an impeller (e.g., for a centrifugal compressor), or the like.

In the illustrated example, the compression mechanism 120 has a suction port 122, an intermediate injection port 124, and a discharge port 126. The compression mechanism 120 is configured to suction working fluid from the suction inlet 114 via the suction port 122 and discharge working fluid into the discharge chamber 104 via the discharge port 126. The intermediate injection port 124 is in fluid connection with the intermediate-pressure chamber 106 and is configured to supply working fluid in the intermediate-pressure chamber 106 into the compression mechanism 120. In an embodiment, the discharge port 126 can be fitted with a valve 128 (e.g., a valve plate, dynamic non-reversing valve, a one-way valve) to ensure that working fluid is flowing into the discharge chamber 104 via the discharge port 126, and not backwards from the normal flow direction.

During operation, the compression mechanism 120 suctions working fluid at a relatively lower pressure (e.g., at a suction pressure P_S, at a first pressure) from the suction inlet 114, compresses the working fluid, and discharges the compressed working fluid at a relatively higher pressure (e.g., at a discharge pressure P_D, at a second pressure) into the discharge chamber 104. The compressed working fluid is discharged through the discharge outlet 118 via the discharge chamber 104, as discussed in more detail below. Working fluid at an intermediate pressure P_I (e.g., at a pressure between suction pressure P_S and the discharge pressure P_D, at a third pressure between the first pressure and the second pressure) flows into the compression mechanism 120 from the intermediate-pressure chamber 106. The intermediate pressure working fluid is suctioned from the intermediate inlet 116 via the intermediate pressure chamber 106. The intermediate pressure working fluid mixes with the suction fluid already partially compressed, and the mixture is further compressed and discharged into the discharge chamber 104 as the compressed working fluid.

The compressor 100 includes a motor 140 and a driveshaft 142 that drives the compression mechanism 120 to compress the working fluid. For example, the driveshaft 142 can be connected to a moving part of the compression mechanism (e.g., an orbited scroll, a rotated rotor, a rotated screw, etc.), the rotation of the driveshaft 142 causes the compression mechanism to compress the working fluid. The driveshaft 142 is supported by one or more bearings 143.

In the illustrated embodiment, the motor 140 is an electric motor, which operates according to generally known principles. For example, the motor 140 includes a stator 146 and a rotor 148 that is magnetically rotated by the stator 146. The driveshaft 142 is affixed to the rotor 148 such that the driveshaft 142 rotates along with the rotation of the rotor 148. The driveshaft 142 can, for example, be fixed to the rotor 148 via an interference fit or the like. The motor 140 in other embodiments may be an external electric motor, an internal combustion engine (e.g., a diesel engine or a gasoline engine), or the like. It will be appreciated that in such embodiments the electric motor 140, stator 146, and rotor 148 would not be present in the compressor 100.

A compressor lubricant pump 144 may be attached to the driveshaft 142 on the end that is not connected to the compression mechanism 120 and can be configured to pump lubricant into the compression mechanism 120 via the driveshaft 142. The compressor lubricant pump 114 may be driven mechanically or electrically. The driveshaft 142 includes a lubricant gallery 145 through which lubricant is supplied to the compression mechanism 120. In an embodiment, the lubricant pump 144 may be formed by an opening in the driveshaft 142 in which a tilt of the lubricant gallery 145 (e.g., being angled relative to an axis of the driveshaft 142) results in the centrifugal force of the rotating driveshaft 142 providing a pumping action of lubricant into and through the lubricant gallery 145.

The compressor 100 has a lubricant supply passage 150 that extends from the discharge chamber 104 to the intermediate-pressure chamber 106. The lubricant supply passage 150 fluidly connects the first lubricant sump 110 of the discharge chamber 104 to second lubricant sump 112 of the intermediate-pressure chamber 106. The lubricant supply passage 150 is configured to direct lubricant from the first lubricant sump 110 into the intermediate-pressure chamber 106. The lubricant supply passage 150 is shown in FIG. 2 as a passage formed externally to the compressor housing 102. However, it should be appreciated that the lubricant supply passage 150 in other embodiments may be formed inside the compressor housing 102 and/or as part of the compressor housing 102.

The lubricant supply passage 150 includes a lubricant sump valve 152 configured to control a flow of lubricant through the lubricant supply passage 150 from first lubricant sump 110 of the discharge chamber 104 to the second lubricant sump 112 of the intermediate-pressure chamber 106. For example, opening of the lubricant sump valve 152 increases the flowrate of lubricant from the first lubricant sump 110 to the second lubricant sump 112 (through the lubricant supply passage 150). For example, the lubricant sump valve 152 is closed to decrease the flowrate of lubricant from the first lubricant sump 110 to the second lubricant sump 112 (through the lubricant supply passage 150). It should be appreciated that the terms “open,” “opening,” “close,” “closing,” etc. as used herein for the lubricant sump valve 152 generally refers to an incremental changing of the position of the valve and not to an absolute position (e.g., being at 0% open, at its maximum flowrate/size, etc.). For example, closing the valve refers to moving a position of the valve to be closer to fully close, and opening the valve refers to moving a position of the valve to be closer to fully open.

In an embodiment, the lubricant supply passage 150 can include a lubricant cooler 154. The lubricant cooler 154 is configured to cool the lubricant flowing through the lubricant supply passage 150. The lubricant cooler 154 can cool the temperature of the lubricant from T₄ to T₅. T₄ is equal to or lower than T₁, the temperature of the discharge sump 110, and is higher than T₅. The lubricant cooler 154 can be controlled to keep the lubricant temperature below a predetermined maximum temperature to prevent lubricant breakdown or be controlled to lower the lubricant temperature to achieve a desirable viscosity. The lubricant cooler 154 can be a heat exchanger configured to cool the lubricant flowing through the lubricant supply passage 150. For example, the lubricant cooler 154 in an embodiment may be configured to utilize a portion of the cooler working fluid in the heat transfer circuit to cool the lubricant. For example, the lubricant cooler 154 in another embodiment may be configured to utilize a different fluid than the working fluid (e.g., the first process fluid, external water, etc.) to cool the lubricant.

The compressor 100 includes one or more sensors. In the illustrated embodiment, the compressor 100 includes lubricant sump sensors (e.g., 160a, 160b, and 160c). Each lubricant sump sensor is configured to detect a lubricant level in its respective sump (e.g., detects the level of lubricant in a respective lubricant sump). A (first) lubricant sump sensor 160a senses a lubricant level L₁ in the first sump 110. A (second) lubricant sump sensor 160b senses a lubricant level L₂ in the second sump 112. A (third) lubricant sump sensor 160c senses a lubricant level L₃ in a third sump 170.

The lubricant sump sensors 160a, 160b, and 160c can be configured to detect additional lubricant conditions, such as, but not limited to, temperature, pressure, and viscosity. For example, the (first) lubricant sump sensor 160a can be configured to sense a temperature T₁ of the first sump 110, in addition to the lubricant level L₁. The (second) lubricant sump sensor 160b can be configured to sense a temperature T₂ of the second sump 112, in addition to the lubricant level L₂. The (third) lubricant sump sensor 160c can be configured to sense a temperature T₃ of a third sump 170, in addition to the lubricant level L₃.

The compressor 100 includes a controller 161. The controller 161 controls operation of the compressor 100. In particular, the controller 161 controls the lubricant sump valve 152. The controller 161 may also control overall operation of the compressor 100 (e.g., speed of the compressor 100, speed of the motor 140, and the like). For example, a controller 161 can be configured to receive lubricant levels (L_1, L_2, and L₃) in a sump detected by lubricant sump sensors 160a, 160b, and 160c. The controller can be further configured to compare the lubricant levels with predetermined values and instruct the lubricant sump valve 152 to open or close depending on the results of the comparison. The controller can be further configured to receive other information, such as, but not limited to, temperature, pressure, and viscosity of the lubricant and control the lubricant sump valve 152. The controller 161 in the Figures and described below is described/shown as a single component. However, it should be appreciated that a “controller” as shown in the Figures and described herein may include multiple discrete or interconnected components that include a memory (not shown) and a processor (not shown) in an embodiment. In an embodiment, the controller 161 may be a controller of the HVACR system the compressor 100 is connected to (e.g., the HVACR system 1 in FIG. 1).

The lubricant sump valve 152 is configured to operate based on the lubricant level(s) L₁, L₂, L₃ in one or more of the lubricant sumps 110, 112, 170. For example, the lubricant sump valve 152 may be operated by the controller 161 as discussed above. In an embodiment, the lubricant sump valve 152 is controlled based on the lubricant level L₂ in the second lubricant sump 112. The lubricant sump valve 152 can be configured to adjust flow so that the lubricant level L₂ in the second lubricant sump 112 is at or above a minimum level (e.g., a predetermined minimum level).

For example, when the controller 161 determines that the lubricant level the level L₂ of lubricant in the second lubricant sump 112 is lower than a predetermined minimum level, the controller 161 can instruct the lubricant sump valve 152 to open to increase the flowrate of lubricant from the first lubricant sump 110 to the second lubricant sump 112. In another example, when the level of lubricant in the second lubricant sump 112 is higher than a maximum level (e.g., a predetermined maximum level), the lubricant sump sensor 160b detects the lubricant level being high and sends the lubricant level to the controller 161, which in turn directs the lubricant sump valve 152 to close and reduce or stop the lubricant flow.

In an embodiment, the controller 161 can be configured to receive information other than lubricant levels and control the lubricant sump valve 152. The additional information can be, for example, temperatures T₁, T₂, and T₃ of the oil sumps 110, 112, and 170, respectively.

As shown in FIG. 2, the compressor 100 can have an optional third lubricant sump 170 disposed in the intermediate-pressure chamber 106 above the second lubricant sump 112. The drive shaft 142 is in connection with the lubricant in the third lubricant sump 170 via a lubricant pump 144 and can supply lubricant from the third lubricant sump 170 to the compression mechanism 120 via the lubricant gallery 145 in the driveshaft 142. The lubricant gallery 145 may also supply lubricant to other parts along the driveshaft 142 (e.g., to the bearing(s) 143), etc.). For example, the lubricant pump 144 may be formed by an opening in the end of the driveshaft 142, in which the lubricant gallery 145 being angled relative to the axis of the driveshaft 142 causes the rotation of the driveshaft 142 to suction lubricant into and through the lubricant gallery 145.

In an embodiment, the compressor 100 can include a lubricant pump 172. The lubricant pump 172 can be configured to transfer lubricant from the second lubricant sump 112 to the third lubricant sump 170. The lubricant pump 172 can be configured to maintain a minimum level L₃ (e.g., predetermined minimum level) of lubricant in the third lubricant sump 170. For example, the lubricant pump 172 may operate using the lubricant sensor 160c for the third lubricant sump 170.

It should be appreciated that the driveshaft lubricant pump 144 in other embodiments may be configured to pump directly from the second lubricant sump 112. For example, the driveshaft lubricant pump 144 in an embodiment may be formed by a hose, conduit, etc. that connects the end of the driveshaft 142 directly to the second lubricant sump 112. The rotation force of the driveshaft 142 then causes the lubricant to be suctioned into and through the hose, conduit, etc. into the lubricant gallery 145 of the driveshaft 142. The illustrated embodiment is a horizontal compressor. It is appreciated that the compressor 100 in an embodiment may be a vertical compressor in which an end of the drive shaft 142 is disposed in the second lubricant sump 112 and pumps directly from the second lubricant sump 112. In such embodiments, the compressor 100 does not include the third sump 170.

The compressor 100 can include a lubricant separator 176 in the discharge chamber 104. The lubricant separator 176 can partition the discharge chamber 104 into sub-chambers 104a and 104b. The working fluid discharge outlet 118 connects to the sub-chamber 104a, and the discharge port 126 of the compression mechanism 120 connects to sub-chamber 104b. The material for the lubricant separator 176 is not particularly limited, as long as the lubricant separator is gas permeant and can trap lubricant contained in the working fluid exhausted from the compression mechanism. In the illustrated embodiment, the lubricant separator 176 is disposed in the discharge chamber 104; however, it is appreciated that a lubricant separation mechanism can be disposed outside of the compressor housing. It is also appreciated that the lubricant separator 176 can be shaped in various forms as long as it can remove lubricant from the working fluid discharged from the compression mechanism 120. For example, the lubricant separator 176 can be cup-shaped and attached to inside of the opening where the working fluid discharge outlet 118 is attached. In another embodiment, the lubricant separator 176 can be a passage or a labyrinth.

In operation of the illustrated embodiment, the compressed working fluid is exhausted from the compression mechanism 120 via the discharge port 126 into the sub-chamber 104b and passes through the lubricant separator 176 to the sub-chamber 104a before being exhausted from the working fluid discharge outlet 118. When the working fluid passes through the lubricant separator 176, lubricant entrained in the warm working fluid is captured and returned to the first lubricant sump 110. It is appreciated that this mechanism can reduce the amount of lubricant exiting from the working fluid discharge outlet 118 and entering the refrigeration circuit. It is further appreciated that the efficiency and reliability of the HVACR system can be improved because the amount of lubricant deposited in the refrigeration circuit, which can block the flow of the working fluid and reduce efficiency of heat exchange, can be reduced.

In FIG. 2, the working fluid lines 114E, 116E, and 118E are part of the refrigeration circuit attached to the compressor 100. The suction inlet line 114E can be the working fluid line 30 in FIG. 1, the intermediate vapor inlet line 116E can be the working fluid line 32 in FIG. 1, and the working fluid discharge outlet line 118E can be the working fluid line 24 in FIG. 1. An optional valve 180, which is a bypass valve that fluidly connects the suction inlet line 114E and the intermediate vapor inlet line 116E, can be installed in the refrigeration circuit, which can be the adjustment valve 20 in FIG. 1. In an embodiment, the valve 180 is disposed outside of the compressor housing 102.

In operation, for example, when it is determined that the working fluid entering the compression mechanism 120 from the suction inlet line 114E has a pressure (P_S) that is lower than the predetermined minimum pressure, the valve 180 can be operated to allow the working fluid in the intermediate vapor inlet line 116E to flow into the suction inlet line 114E and mix with the working fluid in the suction inlet line 114E and adjust the condition of the working fluid (e.g., temperature, pressure) that enters the compression mechanism 120. Alternatively, for example, when it is determined that the working fluid entering the compression mechanism 120 from the suction inlet line 114E has a pressure that is higher than the predetermined maximum pressure, the valve 180 can be operated to reduce or stop the flow of the working fluid in the intermediate vapor inlet line 116E flowing into the suction inlet line 114E.

In operation, for example during changes of operating modes, e.g., changing speed of a compressor, a large amount of lubricant will be drawn into the compression mechanism 120, lowering the lubricant level in the second lubricant sump 112. The second lubricant sump level sensor 160b can detect the change in the lubricant level and send a signal L₂ to control the lubricant sump valve 152 via the controller 161 to open the lubricant sump valve 152, and the lubricant can be transferred quickly from the first lubricant sump 110 to the second lubricant sump 112 to supply the lubricant. The first lubricant sump 110 provides a buffer system that can transfer lubricant to the second lubricant sump 112, which can avoid the second lubricant sump 112 from being emptied and avoid damage to compressor mechanism 120 due to inadequate lubrication. The first lubricant sump 110 also provides buffering capacity during startup conditions of the compressor, when the compressor is run at higher speeds to pull down temperature for a conditioned space, as fast as possible, which pumps/uses more lubricant than used during normal operations of the compressor.

It is appreciated that a compressor with multiple sumps as described above provides a reliable compressor because the lubricant level in the second lubricant sump can be kept at a desired level, and the risk of “dry operation,” or the operation without lubricant, of the compressor can be reduced. It is also appreciated that since the first lubricant sump 110 is provided inside the compressor housing 102, the compressor does not require any larger footprint than a compressor with one lubricant sump with less lubricant-buffering capacity. It is also appreciated that such design allows the use of existing compressor mechanisms, either in vertical or horizontal orientations, and the compressor can be a vertical compressor, in which the discharge chamber and the intermediate-pressure chamber are arranged vertically side-by-side, or a horizontal compressor, in which the discharge chamber and the intermediate-pressure chamber are arranged horizontally side-by-side.

In an embodiment, the lubricant passing through the lubricant supply passage 150 can be cooled to regulate the temperature of the lubricant. The lubricant at the discharge side of a compressor is warm and has higher amount of working fluid dissolved in the lubricant. By cooling the lubricant passing through the lubricant supply passage, the working fluid dissolved in the lubricant can be released into the intermediate-pressure chamber, and the working fluid as well as lubricant can be reused in the compressor. It is appreciated that such cooling mechanism can improve the efficiency of the compressor because the working fluid dissolved in the lubricant can be recovered and used for refrigeration. It is also appreciated that the cooling mechanism allows the use of low viscosity lubricant, such as, but not limited to, Solest 35, Solest 120, and Emkarate RL32H. This is because the lubricant in the second lubricant sump can be kept relatively cool, which dissolves less working fluid in the lubricant, and accordingly, low viscosity lubricant can be used.

In an embodiment, the selected working fluid includes a refrigerant, such as R-134a, or a refrigerant having a relatively lower global warming potential (GWP) than R-134a and that may be utilized as a replacement refrigerant for R-134a. In an embodiment, the selected working fluid can include a refrigerant such as, for example, R1234ze(E), R-513A, R452A, R454A, R454B, R454C, R32, Hydrocarbons, other refrigerant blends, or the like.

FIG. 3 is a flowchart of a method 300 for operating a compressor with multiple lubricant sumps, according to an embodiment. The method 300 is described below with respect to the compressor 100 shown in FIG. 2. However, it will be appreciated that the method 300 can be used to operate compressors with different configurations. In an embodiment, the method 300 may be employed by the compressor 12 in the working fluid circuit 10. The method 300 starts at 310.

At 310, the compression mechanism 120 is driven by the motor 140. As the motor 140 operates, working fluid is drawn into the compression mechanism 120. The method 300 then proceeds in parallel to 320 and 330.

At 320, the motor 140 drives a compression mechanism 120 to suction working fluid into the compressor 100 via a suction inlet 114. Also, at 330, an intermediate-pressure working fluid is injected into the compression mechanism 120 from the intermediate-pressure chamber 106 via the intermediate injection port 124. The suction working fluid and the intermediate-pressure working fluid are both compressed in the compression mechanism 120. The method 300 then proceeds to 340.

At 340, the suctioned working fluid and the injected intermediate-pressure working fluid are compressed into a compressed working fluid by the compression mechanism 120. The method 300 then proceeds to 350.

At 350, the compressed working fluid obtained by compressing the working fluids from suction inlet 114 and intermediate injection port 124 is discharged into a discharge chamber 104. The method 300 then proceeds to 360.

At 360, the compressed working fluid is discharged from the discharge port 118.

Accordingly, the method 300 can be a continuous process that is performed during the operation of the compressor 100. It is appreciated that multiple operations of 310-360 can be performed in the compressor 100 simultaneously, either synchronously or being staggered, starting at separate times.

FIG. 4 is a flowchart of a method 400 for controlling a lubricant level in a compressor with multiple lubricant sumps, according to an embodiment. The method 400 is described below with respect to the compressor 100 shown in FIG. 2. However, it will be appreciated that the method 400 can be used to operate compressors with different configurations. In an embodiment, the method 400 may be employed by the compressor 12 in the working fluid circuit 10. The method 400 starts at 410.

At 410, the compressor 100 has lubricant in the lubricant sumps 110, 112, and 170 in which the lubricant sumps 110, 112, and 170 are part of the lubricant circuit for supplying lubricant to the moving parts of the compressor 100. The compressor 100 is either off or in a steady state of operation, where the lubricant pumped into the compression mechanism 120 and the lubricant returning from the compression mechanism 120 is in equilibrium. The lubricant level in the second lubricant sump 112 is higher than a predetermined minimum level of lubricant threshold, L_2min, and the lubricant sump valve 152 in the lubricant supply passage 150 is closed. The L_2min is at least the minimum level of lubricant in the second lubricant sump 112 that is needed for maintaining the adequate supply of lubricant to the moving parts of the compressor during normal operations of the compressor, e.g., equilibrium level of lubricant, e.g., based on the lubricant entrained in the compressed fluid and/or drained from the compressor parts and returned to the lubricant sump of the compressor.

In an embodiment, the second lubricant sump 112 has a lubricant level sensor 160b that is configured to send information of the lubricant level (L₂) of the second lubricant sump to the controller 161. It is appreciated that additional sensors 160a and 160c can be disposed in the first lubricant sump 110 and the third lubricant sump 170 to detect and send information of the lubricant level (L₁) of the first lubricant sump 110 or the information of the lubricant level (L₃) of the third lubricant sump 170 to controller 161. The method 400 then proceeds to 412.

At 412, the compressor 100 can be started or can have a change in operational conditions, e.g., low speed to high speed. The method 400 then proceeds to 414. Alternatively, when the decrease in the lubricant level (L₂) is expected as a result of the change in operational conditions, the method 400 can optionally proceed to 416 instead of 414.

At 414, the controller 161 instructs the lubricant sump valve 152 to remain closed. The method 400 then proceeds to 418. Alternatively, at 416, the controller 161 instructs the lubricant sump valve 152 to open. The method 400 then proceeds to 418.

For example, when the compressor speed is changed from low speed to high speed in a scroll compressor, the centrifugal action of the drive shaft can shift the lubricant distribution inside the compression mechanism and can temporarily create a low-lubricant condition in the compression mechanism 120. At least because of the increased pumping speed, high volume of the lubricant can be pumped into the compressor and the volume and L₂ is expected to decrease until the volume of the lubricant pumped into the compression mechanism and the amount of the lubricant returning from the compression mechanism reach a new equilibrium. When the decrease of L₂ is expected, the lubricant sump valve can be opened at 416 before L₂ reaches L_2min, and the lubricant in the first lubricant sump 110 can be allowed to flow from the first lubricant sump 110 to the second lubricant sump 112 to compensate for the expected decrease. The first lubricant sump 110 is able transfer the lubricant until the level of lubricant in the second lubricant sump 112 reaches the predetermined desired level.

In another example, when a compressor is operated at the second speed and then the speed is reduced to the first speed, the compression mechanism will draw less volume of lubricant into the compression mechanism and an increase of L₂ is expected. Accordingly, the lubricant sump valve 152 can be kept closed at 414 to prevent increase of L₂ to an undesirably high level.

At 418, the lubricant level L₂ is detected by the sensor 160b in the intermediate-pressure chamber 106 and sent to the controller 161. The method 400 then proceeds to 420.

At 420, the controller 161 compares the lubricant level L₂ to L_2min. When the controller 161 determines that L₂ is higher than L_2min, then the method proceeds to 422. When the controller 161 determines that L₂ is equal to or lower than L_2min, then the method proceeds to 424.

At 422, the controller 161 instructs the lubricant sump valve 152 to keep the previous state. If the lubricant sump valve 152 was closed at 414, the lubricant sump valve 152 is instructed to remain closed. If the lubricant sump valve 152 was opened at 416, the lubricant sump valve 152 is instructed to remain open. The method 400 then goes back to 418.

At 424, the controller 161 instructs the lubricant sump valve 152 to open or remain open so that the lubricant can flow from the first lubricant sump 110 to the second lubricant sump 112 through the lubricant supply passage 150. If the lubricant sump valve 152 was closed at 414, the lubricant sump valve 152 is instructed to open. If the lubricant sump valve 152 was opened at 416, the lubricant sump valve 152 is instructed to remain open. The lubricant will naturally flow from the first lubricant sump 110 to the second lubricant sump 112 because the pressure inside the discharge chamber 104 (P_D) is higher than the pressure inside the intermediate-pressure chamber 106 (P_I). Then, the method 400 proceeds to 426.

At 426, the lubricant level L₂ is detected by the sensor 160b in the intermediate-pressure chamber 106 and sent to the controller 161. The method 400 then proceeds to 428.

At 428, the controller 161 compares the lubricant level L₂ to a predetermined maximum level of lubricant threshold, L_2max. When the controller 161 determines that L₂ is lower than L_2max, then the method proceeds to 430. When the controller 161 determines that L₂ is equal to or higher than L_2max, then the method proceeds to 432. In an embodiment, the L_2max is a level with which the compressor can be operated normally, without damaging the compressor mechanism, e.g., by flooding the inner mechanism of the compressor with lubricant.

At 430, the controller 161 instructs the lubricant sump valve 152 to remain open. The method 400 then goes back to 426.

At 432, the controller 161 instructs the lubricant sump valve 152 to close so that the lubricant flow from the first lubricant sump 110 to the second lubricant sump 112 is stopped. Then, the method proceeds to 418.

The method 400 can be continuously performed while the compressor is operating and/or can also be performed for a predetermined period of time after the compressor is switched off. For example, the method 400 can be performed to allow the sumps to equalize through valve 150 when the compressor is turned off.

It is appreciated that method 400 is shown for illustrative purposes only, and the method for controlling the flowrate of lubricant through the lubricant supply passage 150 is not limited to these examples. It is appreciated that the flowrate can be controlled according to various operating conditions of the compressor and the working fluid circuit the compressor 100 is used in.

Aspects

It is noted that any of aspects 1-9 can be combined with any one or more of aspects 10-15, 16-18 or both. Any one of aspects 10-15 can be combined with any one of aspects 16-18.

• • Aspect 1. A compressor comprising: a compressor housing; a discharge chamber and an intermediate-pressure chamber each disposed within the compressor housing, the discharge chamber having a first lubricant sump, and the intermediate-pressure chamber having a second lubricant sump; a suction inlet and a discharge outlet formed in the compressor housing; a compression mechanism disposed within the compressor housing, the compression mechanism configured to suction working fluid from the suction inlet and discharge working fluid into the discharge chamber, the compression mechanism including an intermediate injection port fluidly connected to the intermediate-pressure chamber; and a lubricant supply passage extending from the discharge chamber to the intermediate-pressure chamber, the lubricant supply passage including a lubricant sump valve configured to control a flow of lubricant through the lubricant supply passage from first lubricant sump of the discharge chamber to the second lubricant sump of the intermediate pressure chamber, and wherein the lubricant in the second lubricant sump is supplied to at least the compression mechanism.
  • Aspect 2. The compressor according to aspect 1, wherein the lubricant supply passage includes a lubricant cooler configured to cool the lubricant flowing through the lubricant supply passage.
  • Aspect 3. The compressor according to any one of aspects 1-2, further comprising: a lubricant sump sensor configured to detect a lubricant level in the second lubricant sump and a controller, wherein the lubricant sump sensor is configured to send the lubricant level in the second lubricant sump to the controller, and the controller is configured to control the lubricant sump valve so as to adjust the flow of lubricant through the lubricant supply passage based on the lubricant level of the second lubricant sump.
  • Aspect 4. The compressor according to any one of aspects 1-3, further comprising: a lubricant pump configured to transfer the lubricant in the second sump to the compression mechanism.
  • Aspect 5. The compressor according to any one of aspects 1-4, further comprising an intermediate vapor injection inlet that is fluidly connected with the intermediate-pressure chamber.
  • Aspect 6. The compressor according to any one of aspects 1-5, further comprising: a third lubricant sump disposed in the intermediate-pressure chamber above the second lubricant sump; a second lubricant pump configured to transfer the lubricant from the second lubricant sump into the third lubricant sump; and a driveshaft including a first end coupled to the compression mechanism, a second end disposed in the third lubricant sump, and a lubricant gallery, the lubricant in the third lubricant sump supplied to the compressor mechanism through the lubricant gallery by rotation of the driveshaft.
  • Aspect 7. The compressor according to any one of aspects 1-6, further comprising a third lubricant sump sensor that is configured to detect the lubricant level in the third lubricant sump, wherein the pump is configured to operate based on the lubricant level in the third lubricant sump so as to maintain the level of lubricant in the third lubricant sump.
  • Aspect 8. The compressor according to any one of aspects 1-7, wherein the compressor is a horizontal compressor, wherein the discharge chamber and the intermediate-pressure chamber are arranged horizontally side-by-side.
  • Aspect 9. The compressor according to any one of aspects 1-7, wherein the compressor is a vertical compressor, wherein the discharge chamber and the intermediate-pressure chamber are arranged vertically side-by-side.
  • Aspect 10. A heating, ventilation, air conditioning, and refrigeration (HVACR) system, comprising: a working fluid circuit, including: a compressor, a condenser, at least one expander, and an evaporator, fluidly connected, wherein a working fluid flows therethrough, wherein the compressor comprises: a compressor housing; a discharge chamber and an intermediate-pressure chamber each disposed within the compressor housing, the discharge chamber having a first lubricant sump, and the intermediate-pressure chamber having a second lubricant sump; a suction inlet and a discharge outlet formed in the compressor housing; a compression mechanism disposed within the compressor housing, the compression mechanism configured to suction working fluid from the suction inlet and discharge working fluid into the discharge chamber, the compression mechanism including an intermediate injection port fluidly connected to the intermediate-pressure chamber; and a lubricant supply passage extending from the discharge chamber to the intermediate-pressure chamber, the lubricant supply passage including a lubricant sump valve configured to control a flow of lubricant through the lubricant supply passage from first lubricant sump of the discharge chamber to the second lubricant sump of the intermediate pressure-chamber, and wherein the lubricant in the second lubricant sump is supplied to at least the compression mechanism.
  • Aspect 11. The system of aspect 10, wherein the compressor further comprises a lubricant cooler configured to cool the lubricant flowing through the lubricant supply passage.
  • Aspect 12. The system of any one of aspects 10-11, wherein the compressor further comprises a lubricant sump sensor configured to detect a lubricant level in the second lubricant sump and a controller, wherein the lubricant sump sensor is configured to send the lubricant level in the second lubricant sump to the controller, and the controller is configured to control the lubricant sump valve so as to adjust the flow of lubricant through the lubricant supply passage based on the lubricant level of the second lubricant sump.
  • Aspect 13. The system according to any one of aspects 10-12, wherein the system further comprises an intermediate vapor injection line, which is fluidly connected to the intermediate-pressure chamber, and the compressor further comprises an intermediate vapor injection inlet that is fluidly connected with the intermediate-pressure chamber.
  • Aspect 14. The system according to any one of aspects 10-13, wherein the compressor is a horizontal compressor, wherein the discharge chamber and the intermediate-pressure chamber are arranged horizontally side-by-side.
  • Aspect 15. The system according to any one of aspects 10-13, wherein the compressor is a vertical compressor, wherein the discharge chamber and the intermediate-pressure chamber are arranged vertically side-by-side.
  • Aspect 16. A method for operating a compressor comprises: driving, with a motor, a compression mechanism to suction working fluid into the compressor via a suction inlet, compress the working fluid into a compressed working fluid, and discharge the compressed working fluid from the compressor via a discharge outlet, the compressor including a compressor housing with the suction inlet and the discharge outlet, a discharge chamber with a first lubricant sump disposed within the compressor housing, and an intermediate-pressure chamber with a second lubricant sump disposed within the compressor housing; injecting intermediate-pressure working fluid from the intermediate-pressure chamber into the compression mechanism, the intermediate-pressure working fluid being compressed by the compression mechanism and discharged as part of the compressed working fluid; and directing lubricant from the first lubricant sump of the discharge chamber to the second lubricant sump of the second lubricant sump through a lubricant supply passage extending from the discharge chamber to the intermediate-pressure chamber, which includes detecting a lubricant level in the second lubricant sump and controlling, via a lubricant sump valve, a flowrate of the lubricant through the lubricant supply passage.
  • Aspect 17. The method of aspect 16, further comprising: operating the compressor at a first speed; and switching the speed from a first speed to a second speed, which is faster than the second speed, wherein the flowrate of lubricant through the lubricant supply passage is increased when operating in the second speed relative to the operation in the first speed.
  • Aspect 18. The method of any one of aspects 16-17, further comprising: cooling, with a lubricant heat exchanger, the lubricant in the lubricant supply passage passing from the first lubricant sump to the second lubricant sump.

The terminology used in this Specification is intended to describe particular embodiments and is not intended to be limiting. The terms “a,” “an,” and “the” include the plural forms as well, unless clearly indicated otherwise. The terms “comprises” and/or “comprising,” when used in this Specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components.

With regard to the preceding description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size, and arrangement of parts without departing from the scope of the present disclosure. This Specification and the embodiments described are exemplary only, with the true scope and spirit of the disclosure being indicated by the claims that follow.