CN116490784A

CN116490784A - Linear compressor and internal crash cushion

Info

Publication number: CN116490784A
Application number: CN202180077374.1A
Authority: CN
Inventors: 约瑟夫·威尔逊·莱瑟姆; 格雷戈里·威廉·哈恩
Original assignee: Qingdao Haier Refrigerator Co Ltd; Haier Smart Home Co Ltd; Haier US Appliance Solutions Inc
Current assignee: Qingdao Haier Refrigerator Co Ltd; Haier Smart Home Co Ltd; Haier US Appliance Solutions Inc
Priority date: 2020-11-19
Filing date: 2021-11-18
Publication date: 2023-07-25
Also published as: US20220154714A1; EP4230867A4; EP4230867A1; WO2022105829A1

Abstract

A linear compressor or method of operation: driving a motor of the linear compressor to a reference current; and detecting the sampled current during driving of the motor. The linear compressor or method may further provide that: calculating a variance of the current using the sampled current; determining that the calculated variance exceeds a variance threshold; and limiting the reference current based on determining that the calculated variance exceeds a variance threshold.

Description

Linear compressor and internal crash cushion

Technical Field

The present invention relates generally to a compressor for an electrical appliance, such as a compressor for refrigerating an electrical appliance.

Background

Some refrigeration appliances include a sealing system for cooling the refrigeration compartment of the refrigeration appliance. Sealing systems typically include a compressor that generates compressed refrigerant during operation of the sealing system. The compressed refrigerant flows to an evaporator where heat exchange between the refrigeration compartment and the refrigerant cools the refrigeration compartment and food items located therein.

Recently, some refrigeration appliances include a linear compressor for compressing a refrigerant. Linear compressors typically include a piston and a drive coil, and they are housed within a sealed housing. The drive coil generates a force for sliding the piston forward within the chamber. During movement of the piston within the chamber, the piston compresses the refrigerant. The movement of the piston within the chamber is typically controlled such that the compressor does not strike the inner shell (i.e., as an internal collision). Such internal collisions may damage various components of the linear compressor and may be very noisy or annoying to nearby users.

Even when the linear compressor is properly operated (e.g., avoiding an impact due to piston movement), it is possible that a series of internal collisions, such as a hard impact of the refrigeration door or a tilting of the linear compressor, are caused by a considerable impact. Unfortunately, as the linear compressor moves within the housing, a series of internal collisions may occur after a single collision, resulting in abrupt changes in the back emf of the motor, which makes it difficult to control the linear compressor. However, it may be difficult to predict or quickly determine when such a series of internal collisions occur. The addition of a sensor configured to detect significant movement or noise from the linear compressor may allow a wide range of collisions to occur before the system can detect and stop such collisions. Additionally or alternatively, the addition of such sensors may undesirably increase the complexity or expense of the appliance. This in turn may lead to a poor user experience, reduced reliability or unacceptably increased cost of the linear compressor.

It would therefore be useful to provide a linear compressor design or method of operation for quickly detecting or mitigating internal collisions of a linear compressor with the inner surface of a surrounding casing. In particular, it would be advantageous to provide a system or method for detecting or mitigating internal collisions without the need for a separate sensor.

Disclosure of Invention

Various aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one exemplary aspect of the present invention, a method of operating a linear compressor to correct an internal collision between the linear compressor and a shell closing the linear compressor is provided. The method may include: driving a motor of the linear compressor to a reference current; and detecting the sampled current during driving of the motor. The method may further comprise: calculating a variance of the current using the sampled current; determining that the calculated variance exceeds a variance threshold; and limiting the reference current based on determining that the calculated variance exceeds a variance threshold.

In another exemplary aspect of the present invention, a method of operating a linear compressor to correct an internal collision between the linear compressor and a shell closing the linear compressor is provided. The method may include: driving a motor of the linear compressor to a reference current during a plurality of electrical cycles; and detecting the sampled current. Detecting the sampled current may include detecting a discrete sampled current value for each of a plurality of electrical cycles. The method may further comprise: calculating a variance of the current using the sampled current; determining that the calculated variance exceeds a variance threshold; and limiting the reference current based on determining that the calculated variance exceeds a variance threshold independent of the piston position of the motor.

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Drawings

The present invention has been fully described in the specification with reference to the accompanying drawings, which are given by way of illustration to those skilled in the art, and which together with the description enable those skilled in the art to practice the invention, including the best mode thereof.

Fig. 1 is a front elevation view of a refrigeration appliance according to an exemplary embodiment of the present invention.

Fig. 2 is a schematic diagram of certain components of the example refrigeration appliance of fig. 1 with corresponding example oil cooling circuits according to an example embodiment of the invention.

Fig. 3 provides a cross-sectional view of an exemplary linear compressor according to an exemplary embodiment of the present invention.

Fig. 4 provides a cross-sectional view of the exemplary linear compressor of fig. 3 illustrating a flow path.

Fig. 5 provides an exemplary plot of experimental motor parameter estimation.

Fig. 6 provides an exemplary plot of experimental motor parameter estimation.

Fig. 7 provides a flowchart illustrating a method of operating a linear compressor according to an exemplary embodiment of the present invention.

Detailed Description

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is given by way of explanation of the invention, and is not to be construed as limiting the invention. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another, and these terms are not intended to represent the location or importance of the respective components. The terms "upstream" and "downstream" refer to the relative direction of fluid flow in a fluid passageway. For example, "upstream" refers to the direction of fluid flow, and "downstream" refers to the direction of fluid flow. The term "or" is generally intended to be inclusive (i.e., "a or B" is intended to mean "a or B or both").

Turning now to the drawings, FIG. 1 depicts a refrigeration appliance 10 incorporating a sealed refrigeration system 60 (FIG. 2). It should be understood that the term "refrigeration appliance" is used herein in a generic sense to encompass any manner of refrigeration appliance, such as an ice bin, a refrigerator/ice bin combination, and any make or model of conventional refrigerator. In addition, it should be understood that the present invention is not limited to use in refrigeration appliances. Thus, the present invention may be used for any other suitable purpose, such as vapor compression in an air conditioning unit or air compression in an air compressor.

In the exemplary embodiment shown in fig. 1, the refrigeration appliance 10 is depicted as an upright refrigerator having a cabinet or housing 12 defining a plurality of internal refrigeration storage compartments. In particular, the refrigeration appliance 10 includes an upper fresh food compartment 14 having a door 16 and a lower freezer compartment 18 having an upper drawer 20 and a lower drawer 22. Drawers 20 and 22 are "pull-out" drawers in that they may be manually moved into and out of freezer compartment 18 on a suitable sliding mechanism.

Fig. 2 provides a schematic diagram of certain components of the refrigeration appliance 10, including a sealed refrigeration system 60 of the refrigeration appliance 10. In particular, FIG. 2 provides an exemplary oil cooling circuit with a sealed refrigeration system 60 according to an exemplary embodiment of the present invention. It should be appreciated that, unless indicated otherwise, in alternative exemplary embodiments, the exemplary oil cooling circuit of FIG. 2 may be modified or used in or with any suitable appliance. For example, the exemplary oil cooling circuit of fig. 2 may be used in or with a heat pump dryer appliance, a heat pump water heater appliance, an air conditioner appliance, and the like.

The mechanical chamber 10 of the refrigeration appliance 10 may contain means for performing a known vapor compression cycle for cooling air. These components include a compressor 64, a condenser 66, an expansion device 68, and an evaporator 70 connected in series and filled with refrigerant. As will be appreciated by those skilled in the art, the refrigeration system 60 may include other components (e.g., at least one additional evaporator, compressor, expansion device, or condenser). As an example, the refrigeration system 60 may include two evaporators.

Within the refrigeration system 60, the refrigerant typically flows into a compressor 64, which operates to increase the pressure of the refrigerant. This compression of the refrigerant increases its temperature, which is reduced by passing the refrigerant through the condenser 66. In the condenser 66, heat exchange with ambient air is performed to cool the refrigerant. A condenser fan 72 is used to blow air across the condenser 66 to provide forced convection for faster and efficient heat exchange between the refrigerant within the condenser 66 and the surrounding air. Thus, as known to those skilled in the art, increasing the airflow through the condenser 66 may increase the efficiency of the condenser 66, for example, by improving the cooling of the refrigerant contained therein.

An expansion device (e.g., a valve, capillary tube, or other throttling device) 68 receives refrigerant from the condenser 66. From the expansion device 68, the refrigerant enters an evaporator 70. Upon exiting the expansion device 68 and entering the evaporator 70, the pressure of the refrigerant drops. Due to the pressure drop or phase change of the refrigerant, the evaporator 70 is cold with respect to the compartments 14 and 18 of the refrigeration appliance 10, thereby generating cooling air and refrigerating the compartments 14 and 18 of the refrigeration appliance 10. Thus, the evaporator 70 is a heat exchanger that transfers heat from the air passing through the evaporator 70 to the refrigerant flowing through the evaporator 70.

In general, the vapor compression cycle components, associated fans, and associated compartments in the refrigeration circuit are sometimes referred to as a sealed refrigeration system operable to force cool air through the compartments 14, 18 (fig. 1). The refrigeration system 60 depicted in fig. 2 is provided by way of example only. Thus, it is within the scope of the invention to use other configurations of refrigeration systems.

In some embodiments, an oil cooling circuit 200 of an exemplary embodiment of the present invention is shown with a refrigeration system 60. The compressor 64 of the refrigeration system 60 may include or be disposed within a shell 302 (fig. 3), the shell 302 also retaining lubricating oil therein. The lubrication oil may assist in reducing friction between sliding or moving parts of the compressor 64 during operation of the compressor 64. For example, as the piston slides within the cylinder to compress refrigerant, the lubrication oil may reduce friction between the piston and the cylinder of the compressor 64, as will be discussed in more detail below.

During operation of the compressor 64, the temperature of the lubricating oil may rise. Thereby, an oil cooling circuit 200 is provided to assist in discharging heat from the lubricating oil. By cooling the lubricant, the efficiency of the compressor 64 may be improved. Thus, the oil cooling circuit 200 may help to increase the efficiency of the compressor 64 by reducing the temperature of the lubrication oil within the compressor 64, e.g., relative to a compressor without the oil cooling circuit 200.

In an alternative embodiment, oil cooling circuit 200 includes a heat exchanger 210 that is spaced apart from at least a portion of compressor 64. A lubrication oil conduit 220 extends between the compressor 64 and the heat exchanger 210. Lubricating oil from the compressor 64 may flow to the heat exchanger 210 via a lubricating oil conduit 220. As shown in fig. 2, the lubrication oil conduit 220 may include a supply conduit 222 and a return conduit 224. A supply conduit 222 extends between the compressor 64 and the heat exchanger 210 and is configured to direct lubrication oil from the compressor 64 to the heat exchanger 210. Instead, return conduit 224 extends between heat exchanger 210 and compressor 64 and is configured to direct lubrication oil from heat exchanger 210 to compressor 64.

Within heat exchanger 210, the lubricating oil may reject heat to the ambient air surrounding heat exchanger 210. Lubricating oil flows from heat exchanger 210 back to compressor 64 via lubricating oil conduit 220. In this way, the lubrication oil conduit 220 may circulate lubrication oil between the compressor 64 and the heat exchanger 210, and the heat exchanger 210 may reduce the temperature of the lubrication oil from the compressor 64 before returning the lubrication oil to the compressor 64. Thus, the oil cooling circuit 200 may remove the lubrication oil from the compressor 64 via the lubrication oil line 220 after cooling the lubrication oil in the heat exchanger 210, and return the lubrication oil to the compressor 64 via the lubrication oil line 220.

In some embodiments, the heat exchanger 210 is disposed at or adjacent to the fan 72. For example, the heat exchanger 210 may be positioned and oriented such that the fan 72 pulls or pushes air through the heat exchanger 210 to provide forced convection for more rapid and efficient heat exchange between the lubricating oil within the heat exchanger 210 and the ambient air surrounding the refrigeration system 60. In certain exemplary embodiments, the heat exchanger 210 may be disposed between the fan 72 and the condenser 66. Thus, the heat exchanger 210 may be disposed downstream of the fan 72 and upstream of the condenser 66 relative to the air flow from the fan 72. In this way, air from the fan 72 may exchange heat with the lube oil in the heat exchanger 210 before exchanging heat with the refrigerant in the condenser 66.

In an additional or alternative embodiment, the heat exchanger 210 is disposed at or on the condenser 66. For example, the heat exchanger 210 may be mounted to the condenser 66 such that the heat exchanger 210 and the condenser 66 are in conductive thermal communication with each other. Thus, the condenser 66 and the heat exchanger 210 can conductively exchange heat. In this way, the heat exchanger 210 and the condenser 66 may provide heat exchange between the lubricant oil within the heat exchanger 210 and the refrigerant within the condenser 66.

In certain exemplary embodiments, the heat exchanger 210 may be a tube-to-tube heat exchanger 210 integrated within or on the condenser 66 (e.g., a portion of the condenser 66). For example, the heat exchanger 210 may be welded or soldered to the condenser 66. In an alternative embodiment, heat exchanger 210 is disposed on a portion of condenser 66 that is between the inlet and the outlet of condenser 66. For example, the refrigerant may enter the condenser 66 at a first temperature (e.g., one hundred fifty degrees Fahrenheit (150F.)) at an inlet of the condenser 66, and the heat exchanger 210 may be disposed on the condenser 66 downstream of the inlet of the condenser 66 such that the refrigerant immediately upstream of the portion of the condenser 66 in which the heat exchanger 210 is mounted may have a second temperature (e.g., ninety degrees Fahrenheit (90F.)).

The heat exchanger 210 may also be disposed on the condenser 66 upstream of the outlet of the condenser 66 such that the refrigerant immediately downstream of the portion of the condenser 66 where the heat exchanger 210 is mounted may have a third temperature (e.g., one hundred fifty degrees Fahrenheit (105F.), and the refrigerant may exit the condenser 66 at the outlet of the condenser 66 at a fourth temperature (e.g., ninety degrees Fahrenheit (90F)). Thus, during operation of the compressor 64, the refrigerant within the condenser 66 may rise in temperature at the portion of the condenser 66 where the heat exchanger 210 is installed, so as to cool the lubricating oil within the heat exchanger 210. However, the portion of the condenser 66 downstream of the heat exchanger 210 may assist in rejecting heat to the ambient air surrounding the condenser 66.

Turning now to fig. 3 and 4, various cross-sectional views of a linear compressor 300 of an exemplary embodiment of the present invention are provided. As discussed in more detail below, the linear compressor 300 is operable to increase the pressure of the fluid within the chamber 312 of the linear compressor 300. Linear compressor 300 may be used to compress any suitable fluid, such as a refrigerant. In particular, linear compressor 300 may be used in a refrigeration appliance, such as refrigeration appliance 10 (fig. 1) where linear compressor 300 may be used as compressor 64 (fig. 2). As can be seen in fig. 3, the linear compressor 300 defines an axial direction a and a radial direction R. The linear compressor 300 may be enclosed within a gas-tight or airtight housing 302. In other words, the linear compressor 300 may be enclosed within the interior volume 303 defined by the shell 302. For example, the linear compressor may be supported within the interior volume 303 by one or more mounting springs 305 that may substantially dampen oscillations or movement of the linear compressor 300 relative to the shell 302. When assembled, the gas-impermeable shell 302 impedes or prevents refrigerant or lubricant from leaking or spilling out of the refrigeration system 60 (fig. 2).

The linear compressor 300 includes a housing 308, the housing 308 extending (e.g., along the axial direction a) between the first end 304 and the second end 306. The housing 308 includes various relatively stationary or non-moving structural components of the linear compressor 300. In particular, the housing 308 includes a cylinder assembly 310 defining a chamber 312. The cylinder assembly 310 may be disposed at or adjacent the second end 306 of the housing 308. The chamber 312 may extend longitudinally along the axis a.

In some embodiments, the motor mounting intermediate portion 314 of the housing 308 (e.g., at the second end 306) supports the stator of the motor. As shown, the stator may include an outer back iron 364 and a drive coil 366 sandwiched between the first end 304 and the second end 306. The linear compressor 300 may also include one or more valves (e.g., a discharge valve assembly 320 at an end of the chamber 312) that allow refrigerant to enter and exit the chamber 312 during operation of the linear compressor 300.

In some embodiments, the discharge valve assembly 320 is mounted to the housing 308 (e.g., at the second end 306). Discharge valve assembly 320 may include muffler housing 322, valve head 324, and valve spring 338.

Muffler shell 322 may include an end wall 326 and a cylindrical side wall 328. A cylindrical sidewall 328 is mounted to the end wall 326, and the cylindrical sidewall 328 extends from the end wall 326 (e.g., along the axial direction a) to the cylinder assembly 310 of the housing 308. A refrigerant outlet conduit 330 may extend from muffler shell 322 or through muffler shell 322 and through shell 302 (e.g., to or in fluid communication with condenser 66-fig. 2) to selectively allow refrigerant to flow out of discharge valve assembly 320 during operation of linear compressor 300.

Muffler housing 322 may be mounted or secured to casing 308, and other components of discharge valve assembly 320 may be disposed within muffler housing 322. For example, a plate 332 of muffler shell 322 at the distal end of cylindrical sidewall 328 may be disposed at or on cylinder assembly 310, and a seal (e.g., an O-ring or gasket) may extend (e.g., along axial direction a) between cylinder assembly 310 and plate 332 of muffler shell 322 to limit leakage of fluid at the axial gap between casing 308 and muffler shell 322. Fasteners may extend through plate 332 into shell 308 to mount muffler shell 322 to shell 308.

In some embodiments, valve head 324 is disposed at or adjacent chamber 312 of cylinder assembly 310. Valve head 324 may selectively cover a passage extending through cylinder assembly 310 (e.g., along axial direction a). Such a passage may be continuous with the chamber 312. When assembled, valve spring 338 may be coupled to muffler housing 322 and valve head 324. Valve spring 338 may be configured to urge valve head 324 toward or against cylinder assembly 310 (e.g., along axial direction a).

A piston assembly 316 having a piston head 318 may be slidably received within the chamber 312 of the cylinder assembly 310. In particular, the piston assembly 316 may slide along the axial direction a within the chamber 312. During sliding movement of the piston head 318 within the chamber 312, the piston head 318 compresses the refrigerant within the chamber 312. As an example, the piston head 318 may slide within the chamber 312 from a top dead center position along the axial direction a toward a bottom dead center position (i.e., an expansion stroke of the piston head 318). When the piston head 318 reaches the bottom dead center position, the piston head 318 changes direction and slides back in the chamber 312 toward the top dead center position (i.e., the compression stroke of the piston head 318). The expansion valve assembly 320 may open with or immediately before the piston head 318 reaches the top dead center position. For example, valve head 324 may be pushed away from cylinder assembly 310, which allows refrigerant to exit chamber 312 and flow through discharge valve assembly 320 to refrigerant outlet conduit 330.

It should be appreciated that the linear compressor 300 may include additional piston heads or additional chambers at opposite ends of the linear compressor 300 (e.g., proximate the first end 304). Thus, in alternative exemplary embodiments, the linear compressor 300 may have multiple piston heads.

In certain embodiments, linear compressor 300 includes an inner back iron assembly 352. The inner back iron assembly 352 is disposed in the stator of the motor. In particular, the outer back iron 364 or the drive coil 366 may extend around the inner back iron assembly 352 (e.g., along a circumferential direction). The inner back iron assembly 352 also has an outer surface. At least one drive magnet 362 is mounted to the inner back iron assembly 352 (e.g., at an outer surface of the inner back iron assembly 352). The drive magnet 362 may face or be exposed to the drive coil 366. In particular, the drive magnet 362 may be spaced apart from the drive coil 366 (e.g., with an air gap along the radial direction R). Thus, an air gap may be defined between the opposing surfaces of the drive magnet 362 and the drive coil 366. The drive magnet 362 may also be mounted or secured to the inner back iron assembly 352 such that the outer surface of the drive magnet 362 is substantially flush with the outer surface of the inner back iron assembly 352. Thus, the drive magnet 362 may be inserted within the inner back iron assembly 352. As such, during operation of the linear compressor 300, the magnetic field from the drive coil 366 may only need to pass through a single air gap between the outer back iron 364 and the inner back iron assembly 352.

As can be seen in fig. 3, the drive coil 366 may extend (e.g., along a circumferential direction) around the inner back iron assembly 352. Generally, during operation of the drive coil 366, the drive coil 366 is operable to move the inner back iron assembly 352 along the axial direction a. As an example, a current source (e.g., including or coupled to the controller 367) may induce a current in the drive coil 366 to generate a magnetic field that attracts the drive magnet 362 and urges the piston assembly 316 to move along the axial direction a to compress the refrigerant within the chamber 312 as described above. In particular, during operation of the drive coil 366, the magnetic field of the drive coil 366 may attract the drive magnet 362 to move the inner back iron assembly 352 and the piston head 318 along the axial direction a. Thus, during operation of the drive coil 366, the drive coil 366 may slide the piston assembly 316 between a top dead center position and a bottom dead center position.

In alternative embodiments, linear compressor 300 includes various components for allowing and/or adjusting the operation of linear compressor 300. In particular, the linear compressor 300 includes a controller 367 configured to regulate operation of the linear compressor 300. The controller 367 is in operative communication with a motor (e.g., a drive coil 366 of the motor), for example. Thus, the controller 367 may selectively activate the drive coil 366, such as by supplying current to the drive coil 366, to compress the refrigerant with the piston assembly 316 as described above. In some embodiments, the controller 367 directs or regulates the current according to a predetermined control loop. For example, as will be appreciated, such a control loop may regulate the supply voltage of the supplied current (e.g., peak voltage or Root Mean Square (RMS) voltage) to a desired reference voltage. To this end, the controller 367 may include suitable components for measuring or estimating the supply current, such as an ammeter. Additionally or alternatively, the controller 367 may be configured to detect or mitigate internal collisions (e.g., according to one or more programmed methods, such as method 700).

The controller 367 includes a memory and one or more processing devices, such as a microprocessor, CPU, or the like, such as a general-purpose or special-purpose microprocessor, operable to execute programmed instructions or micro-control code associated with the operation of the linear compressor 300. The memory may represent a random access memory such as DRAM or a read only memory such as ROM or FLASH. The processor executes programming instructions stored in the memory. The memory may be a separate component from the processor or may be included on a board within the processor. Alternatively, the controller 367 may be configured to perform control functions without the use of a microprocessor (e.g., using a combination of discrete analog or digital logic circuits; such as switches, amplifiers, integrators, comparators, flip-flops, and gates, etc.), rather than relying on software.

The linear compressor 300 also includes one or more spring assemblies 340, 342 mounted to the housing 308. In certain embodiments, a pair of spring assemblies (i.e., first spring assembly 340 and second spring assembly 342) constrain drive coil 366 along axial direction a. In other words, the first spring assembly 340 is disposed proximate the first end 304 and the second spring assembly 342 is disposed proximate the second end 306.

In some embodiments, each spring assembly 340 and 342 includes one or more planar springs mounted or secured to each other. In particular, the planar springs may be mounted or secured to one another such that the respective planar springs of the corresponding assemblies 340 or 342 are spaced apart from one another (e.g., along the axial direction a).

Generally, the pair of spring assemblies 340, 342 assist in coupling the inner back iron assembly 352 to the outer housing 308. In some such embodiments, a first outer set of fasteners 344 (e.g., bolts, nuts, clamps, lugs, welds, solders, etc.) secures the first and second spring assemblies 340, 342 to the housing 308 (e.g., a bracket of the stator), while a first inner set of fasteners 346, radially inward (e.g., near the axial direction a along the perpendicular radial direction R) from the first outer set of fasteners 344 secures the first spring assembly 340 to the inner back iron assembly 352 at the first end 304. In an additional or alternative embodiment, a second inner set of fasteners 350 radially inward (e.g., radially R near the axial direction a) from the first outer set of fasteners 344 secures the second spring assembly 342 to the inner back iron assembly 352 at the second end 306.

The spring assemblies 340, 342 support the inner back iron assembly 352 during operation of the drive coil 366. In particular, the inner back iron assembly 352 is suspended within the stator or motor of the linear compressor 300 by the spring assemblies 340, 342 such that movement of the inner back iron assembly 352 in the radial direction R is prevented or limited while movement in the axial direction a is relatively unimpeded. Thus, the spring assembly 342 may be stiffer along the radial direction R than along the axial direction a. In this way, the spring assemblies 340, 342 may assist in maintaining uniformity of the air gap between the drive magnet 362 and the drive coil 366 (e.g., along the radial direction R) during operation of the motor and movement of the inner back iron assembly 352 in the axial direction a. The spring assemblies 340, 342 may also assist in preventing the side pull of the motor from being transferred to the piston assembly 316 and reacting to friction losses in the cylinder assembly 310.

In an alternative embodiment, the inner back iron assembly 352 includes an outer cylinder 354 and a sleeve 360. A sleeve 360 is disposed on or on the inner surface of the outer cylinder 354. A first interference fit between outer cylinder 354 and sleeve 360 may couple or secure outer cylinder 354 and sleeve 360 together. In alternative exemplary embodiments, sleeve 360 may be welded, glued, fastened, or otherwise connected to outer cylinder 354 via any other suitable mechanism or method.

When assembled, the sleeve 360 may extend about the axial direction a (e.g., along a circumferential direction). In an exemplary embodiment, a first interference fit between outer cylinder 354 and sleeve 360 may couple or secure outer cylinder 354 and sleeve 360 together. In alternative exemplary embodiments, sleeve 360 is welded, glued, fastened, or otherwise connected to outer cylinder 354 via any other suitable mechanism or method. As shown, the sleeve 360 extends within the outer cylinder 354 (e.g., along the axial direction a) between the first end 304 and the second end 306 of the inner back iron assemblies 352, 130. The first spring assembly 340 and the second spring assembly 342 are mounted to a sleeve 360 (e.g., with inner set fasteners 346 and 350).

Outer cylinder 354 may be constructed of or from any suitable material. For example, outer cylinder 354 may be constructed from or with multiple (e.g., ferromagnetic) laminations. The laminations are distributed circumferentially to form an outer cylinder 354 and are mounted to each other or secured together (e.g., with a ring pressed onto the ends of the laminations). The outer cylinder 354 defines a recess extending inwardly (e.g., along the radial direction R) from an outer surface of the outer cylinder 354. The drive magnet 362 may be disposed in a recess on the outer cylinder 354 (e.g., such that the drive magnet 362 is inserted within the outer cylinder 354).

In some embodiments, a piston flexure mount 368 is mounted to the inner back iron assembly 352 and extends through the inner back iron assembly 352. In particular, the piston flexure mount 368 is mounted to the inner back iron assembly 352 via the sleeve 360 and the spring assemblies 340, 342. Thus, the piston flexure mount 368 may be coupled (e.g., threaded) to the sleeve 360 to mount or secure the piston flexure mount 368 to the inner back iron assembly 352. A coupler 370 extends (e.g., along the axial direction a) between the piston flexure mount 368 and the piston assembly 316. The coupler 370 connects the inner back iron assembly 352 and the piston assembly 316 such that movement of the inner back iron assembly 352 (e.g., along the axial direction a) is transferred to the piston assembly 316. The coupler 370 may extend through the drive coil 366 (e.g., along the axial direction a).

The piston flexure mount 368 may define at least one channel 369. A passage 369 of the piston flexure mount 368 extends (e.g., along the axial direction a) through the piston flexure mount 368. Thus, during operation of the linear compressor 300, a fluid flow, such as air or refrigerant, may pass through the piston flexure mount 368 via the channels 369 of the piston flexure mount 368. As shown, one or more refrigerant inlet conduits 331 may extend through the shell 302 to return refrigerant from the evaporator 70 (or another portion of the sealing system 60) (fig. 2) to the compressor 300.

The piston head 318 also defines at least one opening (e.g., selectively covered by a head valve). An opening of the piston head 318 (e.g., along the axial direction a) extends through the piston head 318. Thus, during operation of the linear compressor 300, a flow of refrigerant may pass through the piston head 318 via the opening of the piston head 318 into the chamber 312. In this way, fluid flow (compressed within the chamber 312 by the piston head 318) may flow through the piston flexure mount 368 and the inner back iron assembly 352 to the piston assembly 316.

As shown, the linear compressor 300 may include features for directing oil through the linear compressor 300 and the oil cooling circuit 200 (fig. 2). One or more oil inlet or outlet lines 380, 382 may extend through the shell 302 to direct oil to/from the oil cooling circuit 200.

Optionally, an oil inlet conduit 380 may be coupled to the return conduit 224 of the oil cooling circuit 200 (FIG. 2). Thus, lubricating oil may flow from the heat exchanger 210 to the linear compressor 300 via the oil inlet conduit 380. Optionally, an oil inlet conduit 380 may be provided at or adjacent to sump 376. Thus, lubrication oil to linear compressor 300 at oil feed line 380 may flow into sump 376. As described above, the oil cooling circuit 200 may cool the lubricating oil from the linear compressor 300. After such cooling, the lubricating oil returns to the linear compressor 300 via the oil feed line 380. Thus, the lubrication oil in the oil inlet conduit 380 may be relatively cool and assist in cooling the lubrication oil in the sump 376.

In some embodiments, linear compressor 300 includes a pump 372. The pump 372 may be disposed at or adjacent to a sump 376 of the housing 302 (e.g., within a pump housing 374). The sump 376 corresponds to a portion of the shell 302 at or adjacent to the bottom of the shell 302. Thus, a volume of lubricant 377 within the shell 302 may pool within the sump 376 (e.g., because the lubricant is denser than the refrigerant within the shell 302). During use, pump 372 may pump lubricant 377 from the volume within sump 376 to pump 372 via a supply conduit 378 extending from pump 372 to sump 376. For example, a pair of check valves within the pump housing 374 at opposite ends of the pump 372 may selectively allow oil to flow to/release oil from the pump housing 374 as the pump 372 oscillates within the pump housing 374 (e.g., as driven by oscillation of the housing 308). Additionally or alternatively, the volume of lubricant 377 may be maintained at a predetermined level (e.g., even at the vertical midpoint of pump 372) as pump 372 is actively oscillating.

An internal conduit 384 may extend from the pump 372 (e.g., the pump housing 374) to an oil reservoir 386 defined within the housing 308. In some embodiments, oil reservoir 386 is disposed radially outward from chamber 312 of cylinder assembly 310. For example, the oil reservoir 386 may be defined as extending in a circumferential direction (e.g., about the axial direction a) as an annular chamber surrounding the chamber 312 of the cylinder assembly 310.

In general, lubrication oil may be selectively directed from oil reservoir 386 to cylinder assemblies 310. In particular, one or more passages (e.g., radial passages) may extend from the oil reservoir 386 to the chamber 312. Such radial passages may terminate at a portion of the sliding path of the piston head 318 (e.g., between top dead center and bottom dead center relative to the axial direction a). As the piston head 318 slides within the chamber 312, the side walls of the piston head 318 may receive lubricating oil. In an alternative embodiment, the radial passage terminates in a recess 388 defined by the cylinder assembly 310 within the chamber 312. Thus, the recess 388 may open to the chamber 312. Lubricating oil from reservoir 386 may flow into chamber 312 of cylinder assembly 310 (e.g., via radial passages to grooves 388) to lubricate the movement of piston assembly 316 within chamber 312 of cylinder assembly 310.

The housing 308 may define an oil drain 390 with the chamber 312 and the oil reservoir 386. In some embodiments, an oil drain 390 extends from the oil reservoir 386. For example, an oil drain 390 may extend outwardly from the oil reservoir 386 through the housing 308. Thus, the drain port 390 may be in fluid communication with the oil reservoir 386. During use, at least a portion of the lubrication oil that is forced to the oil reservoir 386 may flow to the oil drain 390 (e.g., as forced by the pump 372). Lubricating oil may exit the housing 308 (and typically the linear compressor 300) from the oil drain 390. In certain embodiments, the drain port 390 is connected in fluid communication to the oil outlet conduit 382. Thus, the pump 372 may generally push lubrication oil from the internal volume 303 through the housing 308 to the drain line 382. The oil outlet pipe 382 may be coupled to the supply pipe 222 of the oil cooling circuit 200 (fig. 2). Thus, pump 372 may push lubrication oil from sump 376 into supply conduit 222. In this way, the pump 372 may supply lubrication oil to the oil cooling circuit 200 in order to cool the lubrication oil from the linear compressor 300, as described above.

The housing 308 may define a gas discharge port 392, either separately from the oil discharge port 390 or in addition to the oil discharge port 390. In particular, a gas vent 392 extends from the oil reservoir 386 through to the interior volume 303. As shown, the gas discharge port 392 is fluidly defined in parallel with the oil drain port 390. Thereby, the fluid is separately guided through the gas discharge port 392 and the oil drain port 390. In general, the gas discharge port 392 may be sized to restrict fluid more than the oil drain port 390. For example, the minimum diameter of the gas discharge port 392 may still be smaller than the minimum diameter of the oil drain port 390. Alternatively, the minimum diameter of the gas discharge port 392 may be less than two millimeters, while the minimum diameter of the oil drain port is greater than four millimeters. In addition to the smaller diameter, the length of the gas discharge port 392 may also be shorter than the length of the oil drain port 390. Under typical pumping operations, the amount of lubrication oil that can pass through the oil drain 390 is greater than the amount of lubrication oil that can pass through the gas drain 392. However, gas (e.g., generated during an exhaust process within the oil reservoir 386) may be allowed to enter the interior volume 303 through the gas exhaust 392 while allowing a continuous flow of lubricating oil from the oil reservoir 386 to the oil drain 390 or chamber 312.

A gas discharge port 392 may be defined at an upper portion of the housing 308 (e.g., an upper end of the oil reservoir 386). Additionally or alternatively, the gas discharge port 392 may extend above the discharge valve assembly 320 (e.g., parallel to the axial direction a). The gas discharge port 392 may also be located below the oil drain port 390 (e.g., vertically V lower than the oil drain port 390). In some embodiments, the gas discharge port 392 is located at the second end 306 of the housing 308. Fluid from the gas discharge port 392 may be directed forward into the interior volume 303.

In some embodiments, an oil shield 394 is provided in front of the gas discharge port 392. As shown, the oil shield 394 may be disposed on the housing 308 (e.g., at the second end 306). A drip passage may be defined between the oil shield 394 and, for example, the muffler shell 322. A drip passage may be defined between the oil shield 394 and, for example, the muffler shell 322. For example, the oil shield 394 may extend outwardly from the housing 308 to a curved or inwardly extending wall portion 396. Additionally or alternatively, the oil shield 394 may extend around a portion of the muffler shell 322. For example, the oil shield 394 may extend 180 ° along the top side of the muffler shell 322. During use, lubrication oil discharged through gas discharge port 392 may be directed downwardly to sump 376. During use, the oil shield 394 may prevent lubricating oil from striking the shell 302 (e.g., at high velocity, which may otherwise cause atomization of the lubricating oil within the interior volume 303).

Turning now to fig. 5 and 6, during use of a linear compressor (e.g., linear compressor 300-fig. 3), the linear compressor may suddenly shift or inadvertently be bumped, such as when the door of the corresponding appliance (e.g., refrigeration appliance 10-fig. 1) is slammed shut. Such displacement or impact may cause the linear compressor to repeatedly collide with the closed shell. For example, with respect to the exemplary embodiment of fig. 3, muffler shell 328 may collide with the inner surface of shell 302. This internal collision may be repeated as the linear compressor 300 swings or oscillates on the support spring 305.

Fig. 5 and 6 provide a pair of exemplary graphs illustrating experimental motor parameter estimates obtained during an internal collision event and resulting changes in one or more control parameters (e.g., reference current according to the disclosed operating methods). In particular, FIG. 5 illustrates the detection line L-S and the reference line L-R over a time span (e.g., measured in seconds or measured according to discrete electrical cycles of the motor). FIG. 6 illustrates a variance line L-V and a variance threshold line L-T calculated over the same time span.

In general, the detection lines L-S illustrate the change in detected supply current (e.g., current at or provided to the motor of the linear compressor 300) over time. Reference line L-R graphically represents the change over time in a reference current that may be used as a control parameter for the control loop of the motor of linear compressor 300 (e.g., adjusted in response to a detected change in supply current). The calculated variance line L-V graphically represents the variance value calculated from the values of the detection lines over time. In general, the variance threshold may remain constant (e.g., as a predetermined value), whereby the variance threshold line L-T is flat over time. As will be described in detail below, the value of the reference current may be changed based on (e.g., in response to) one or more determinations that the one or more calculated variance values exceed a variance threshold. Notably, the change in reference current may be independent of the position of the piston within the linear compressor (e.g., so that internal collisions may be detected without disabling a separate monitoring sequence for determining hard or soft collisions of the piston within the motor). Note that although the detected supply current value, the reference current value, and the calculated variance value are exemplified as peak current values, another suitable current value (e.g., RMS) may be similarly used.

Turning now to fig. 7, an exemplary method of operating a linear compressor (e.g., method 700) is illustrated. As will be appreciated in view of the present disclosure, such a method may be applied to any suitable linear compressor (e.g., linear compressor 300) to detect or correct an internal collision of the linear compressor with a closed shell (e.g., shell 302). In some embodiments, the methods described below may be initiated or directed by the controller 367 (e.g., as or as part of a software program that the controller 367 is configured to initiate).

Advantageously, the methods described herein may allow a corresponding linear compressor to quickly detect or mitigate internal collisions of the linear compressor with the inner surface of the surrounding shell. Additionally or alternatively, such a method may be advantageously performed without the need for additional or detected sensor components.

At 710, method 700 includes driving a motor of a linear compressor to a reference current. For example, as described above, a variable reference current may be used to induce a current in the drive coil of the motor and drive the movement of the piston within the linear compressor. Moreover, the motor may be driven in a substantially continuous or uninterrupted manner such that 710 extends over multiple electrical cycles (e.g., represented on a sine wave of current as will be appreciated).

In general, the motor may be driven according to any suitable reference current control loop. As an example, the supply voltage may be directed to the motor to start the motor. The supply voltage may then be adjusted to reduce the difference or error between the sampled current (e.g., peak current or RMS current) supplied to the linear compressor and the reference current (e.g., reference peak current or reference RMS current). The sampling current may be measured or estimated using any suitable method or mechanism. For example, an ammeter may be used to measure the sampling current as the peak current. The voltage selector of the controller may operate as a proportional-integral (PI) controller to reduce the error between the sampling current and the reference current. At the beginning of 710, the reference current may be a default value (e.g., a default peak current value or peak RMS value) that may be subsequently adjusted (e.g., increased or decreased) during subsequent steps of the method 700, as discussed in more detail below, such that the method 700 reverts to (or otherwise continues to) driving the motor in order to adjust the amplitude of the supply voltage and reduce the error between the current supplied to the linear compressor and the adjusted reference current.

At 720, method 700 includes detecting a sampling current during 710. In other words, when the motor is driven, the current supplied to the motor may be sampled (e.g., as a peak supply current value or RMS current value). In some embodiments, 720 includes detecting discrete sample values over time. Thus, as the motor continues to be driven, the sampled value of the supply current of the motor may continue to be detected. In an alternative embodiment, discrete sampled current values are detected for each electrical cycle. Thereby, at least one sampling value can be obtained for the corresponding electrical cycle. The sampled value may be detected, for example, by detecting a maximum value of the current during each electrical cycle. Additionally or alternatively, the sampled current values may include absolute values of maximum currents for each corresponding electrical cycle, such that the sampled current values are detected in view of the magnitude of the supply current.

In some embodiments, 720 may include detecting a predetermined number of sets of sampled current values. For example, the set may include a window of sequential current values to be stored in the controller. Thus, when a new sampled current value is detected, it may be stored within a group or window. This may continue until the set or window is full (i.e., a predetermined number of sample current values are obtained). Alternatively, the group or window may be a rolling group such that a new sample current value may replace the oldest previous sample current value within the group.

At 730, method 700 includes calculating a variance of the current using the sampled current. The calculated variance may be a recursive variance and thus represent the sampled current values detected over time (e.g., over multiple electrical cycles, even when no previous sampled current values are held or stored in memory). In general, the sampling current can be used in the programmed variance formula. Such variance formulas are known and programmed variance formulas may be provided as or include the variance formulas. As an example, the programmed variance formula (Var (X)) may be or include:

where xi is the detected sampling current value, n is the number of samples for which the variance is calculated, and μ is the average of the values of xi (e.g., calculated as a rolling average, moving average, weighted average, etc.). Alternatively, the variance may be calculated from a predetermined number of groups. In some such embodiments, n is a predetermined number and a predetermined number of sets of values are used for the samples xi. Thus, 730 may include calculating an average of a predetermined number of sets of sampled current values.

Alternatively, 730 may include calculating the variance from the change in the sampled value (ΔX). Thus, 730 may include: calculating a difference between a previous sampling current and a sampling current (i.e., a present sampling current); and calculating the variance based on the difference between the previous sample current and the sample current. As an example, the programmed variance formula may be or include:

Is the sample of the difference of the calculated sampled current values, n is the number of samples of the calculated variance, and μ is the average of the values of Δxi (e.g., calculated as a rolling average, a moving average, a weighted average, etc.). Advantageously, it is possible to prevent an abnormal variance variation between the respective sampling current values from affecting a large variation of any control parameter based on the calculated variance.

At 740, method 700 includes determining that the calculated variance exceeds a variance threshold. For example, the calculated variance value of 730 may be compared to a predetermined variance threshold (e.g., a current peak threshold or a current RMS value), and it may be determined that the calculated variance value of 730 is greater than the variance threshold. Alternatively, this may be repeated such that a plurality (e.g., sequential) of calculated variance values may be determined to exceed the variance threshold.

At 750, method 700 includes limiting a reference current based on 740. In particular, a reference current for driving the motor may be reduced in response to one or more determinations that the calculated variance exceeds a variance threshold. This may be done independently of the piston position of the motor (e.g., as described above).

Alternatively, the decrease may be a decrease in the reference current (e.g., the reference current value at the determined time of 740) by a predetermined decrease value. Additionally or alternatively, a reduction formula may be provided to variably reduce the reference current (e.g., based on the magnitude of the reference current value at the determined time of 740).

In some embodiments, 750 requires that the calculated variance repeatedly exceed a variance threshold. Thus, 750 may depend on determining that the plurality of calculated variance values exceeds (e.g., is prompted by) a predetermined variance. In some such implementations, the plurality of calculated variance values may require that a number of groups (e.g., counts or instances) of calculated variances exceed a variance threshold. Additionally or alternatively, all determinations may be required to occur within a set period of time or number of cycles.

After limiting the reference current, the motor may be driven with the limited or reduced reference current. If a subsequent electrical cycle (e.g., a set number of cycles or a predetermined period of time) passes without additional determination that the calculated variance exceeds the reference threshold, the reference current may be increased (e.g., incrementally) until the adjusted reference current is equal to the default reference current value (or another predetermined reference current value).

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

A method of operating a linear compressor to correct for internal collisions between the linear compressor and a shell closing the linear compressor, the method comprising:

driving a motor of the linear compressor to a reference current;

detecting a sampled current during driving of the motor;

calculating a variance of the current using the sampled current;

determining that the calculated variance exceeds a variance threshold; and

the reference current is limited based on determining that the calculated variance exceeds the variance threshold.
The method of claim 1, wherein the sampled current comprises a peak supply current value, and wherein the reference current comprises a reference peak current value.
The method of claim 1, wherein the sampled current comprises a root mean square current value, and wherein the reference current comprises a reference root mean square current value.
The method of claim 1, wherein the calculated variance is a recursive variance.
The method of claim 1, wherein calculating the variance comprises:

calculating a difference between a previous sampled current and the sampled current; and

A variance is calculated based on the difference of a previously sampled current and the sampled current.
The method of claim 1, wherein driving the motor comprises driving the motor over a plurality of electrical cycles, and wherein detecting the sampled current comprises detecting a discrete sampled current value for each of the plurality of electrical cycles.
The method of claim 6, wherein the sampled current value is an absolute value of a maximum current of a corresponding electrical cycle.
The method of claim 1, wherein detecting the sampled current comprises detecting a predetermined number of sets of sampled current values, and wherein calculating the variance comprises calculating the variance of the predetermined number of sets of sampled current values.
The method of claim 8, wherein calculating the variance comprises calculating an average of the predetermined number of sets of sampled current values.
The method of claim 1, wherein determining that the calculated variance exceeds the variance threshold comprises determining that a plurality of calculated variance values exceeds the predetermined variance, and wherein limiting the reference current is dependent on determining that a plurality of calculated variance values exceeds the predetermined variance.
A method of operating a linear compressor to correct for internal collisions between the linear compressor and a shell closing the linear compressor, the method comprising:

driving a motor of the linear compressor to a reference current during a plurality of electrical cycles;

detecting a sampled current, the detecting the sampled current including detecting a discrete sampled current value for each of the plurality of electrical cycles;

calculating a variance of the current using the sampled current;

determining that the calculated variance exceeds a variance threshold; and

the reference current is limited based on determining that the calculated variance exceeds the variance threshold independent of a piston position of the motor.
The method of claim 11, wherein the sampled current comprises a peak supply current value, and wherein the reference current comprises a reference peak current value.
The method of claim 11, wherein the sampled current comprises a root mean square current value, and wherein the reference current comprises a reference root mean square current value.
The method of claim 11, wherein the calculated variance is a recursive variance.
The method of claim 11, wherein calculating the variance comprises:

calculating a difference between a previous sampled current and the sampled current; and

a variance is calculated based on the difference of a previously sampled current and the sampled current.
The method of claim 11, wherein the sampled current value is an absolute value of a maximum current of the corresponding electrical cycle.
The method of claim 11, wherein detecting the sampled current comprises detecting a predetermined number of sets of sampled current values, and wherein calculating the variance comprises calculating the variance of the predetermined number of sets of sampled current values.
The method of claim 17, wherein calculating the variance comprises calculating an average of the predetermined number of sets of sampled current values.
The method of claim 11, wherein determining that the calculated variance exceeds the variance threshold comprises determining that a plurality of calculated variance values exceeds the predetermined variance, and wherein limiting the reference current is dependent on determining that a plurality of calculated variance values exceeds the predetermined variance.