Linear compressor and internal impact cushion

Abstract

A linear compressor or method of operation: driving a motor of the linear compressor to a reference current; and detecting a sampled current during driving the motor. The linear compressor or method can further provide for: 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 the variance threshold.

Description

Technical Field

[0001] The present invention generally relates to a compressor for electrical appliances, such as a compressor for refrigerating electrical appliances. Background Technology

[0002] Some refrigeration appliances include a sealed system for cooling the refrigeration compartment of the appliance. The sealed system typically includes a compressor that generates compressed refrigerant during operation. The compressed refrigerant flows to an evaporator, where heat exchange between the refrigeration compartment and the refrigerant cools the refrigeration compartment and the food contained therein.

[0003] Recently, some refrigeration appliances have included linear compressors for compressing refrigerant. A linear compressor typically consists of a piston and a drive coil, both housed within a sealed housing. The drive coil generates a force that propels the piston forward within the chamber. During this movement, the piston compresses the refrigerant. This movement is typically controlled to prevent the compressor from slamming against the inner casing (i.e., internal collisions). Such internal collisions can damage various components of the linear compressor and can be very noisy or annoying to nearby users.

[0004] Even when a linear compressor operates properly (e.g., avoiding impacts due to piston movement), a series of internal collisions can still occur due to a considerable shock, such as a violent impact to the refrigerator door or tilting of the linear compressor. Unfortunately, a single impact can be followed by a series of internal collisions as the linear compressor moves within the casing, causing a sudden change in the motor's back electromotive force, making the linear compressor difficult to control. However, it can be difficult to predict or quickly determine when such a series of internal collisions will occur. Adding sensors configured to detect significant movement or noise from the linear compressor may allow a wide range of collisions to occur before the system is able to detect and stop them. Alternatively or additionally, adding such sensors may undesirably increase the complexity or cost of the appliance. This, in turn, can lead to a poor user experience, reduced reliability, or unacceptably increased cost of the linear compressor.

[0005] Therefore, it would be useful to provide a linear compressor design or operating method for quickly detecting or mitigating internal collisions between the linear compressor and the inner surface of the surrounding housing. In particular, it would be advantageous to provide a system or method for detecting or mitigating internal collisions without requiring a separate sensor. Summary of the Invention

[0006] Various aspects and advantages of the present invention will be set forth in the description which follows, or will be apparent from the description, or may be learned by practicing the invention.

[0007] In one exemplary embodiment of the invention, a method is provided for operating a linear compressor to correct for internal collisions between the linear compressor and its enclosure. The method may include: driving a motor of the linear compressor to a reference current; and detecting a sampled current during motor driving. The method may further include: calculating the variance of the current using the sampled current; determining that the calculated variance exceeds a variance threshold; and limiting the reference current based on the determination that the calculated variance exceeds the variance threshold.

[0008] In another exemplary embodiment of the invention, a method is provided for operating a linear compressor to correct for internal collisions between the linear compressor and its housing. The method may include: driving a motor of the linear compressor to a reference current during multiple electrical cycles; and detecting sampled currents. Detecting the sampled currents may include detecting discrete sampled current values ​​for each of the multiple electrical cycles. The method may further include: calculating the variance of the current using the sampled currents; determining that the calculated variance exceeds a variance threshold; and limiting the reference current independently of the motor's piston position based on the determination that the calculated variance exceeds the variance threshold.

[0009] These and other features, aspects, and advantages of the invention will become more readily apparent from the following description and the appended claims. Embodiments of the invention are illustrated in conjunction with the accompanying drawings, which are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention. Attached Figure Description

[0010] The invention is fully and clearly described in the specification with reference to the accompanying drawings, which enables those skilled in the art to implement the invention, including the preferred embodiments thereof.

[0011] Figure 1 This is a front elevation view of a refrigeration appliance according to an exemplary embodiment of the present invention.

[0012] Figure 2 This is an exemplary embodiment of the present invention having a corresponding exemplary oil cooling circuit. Figure 1 A schematic diagram of certain components of an exemplary refrigeration appliance.

[0013] Figure 3 A cross-sectional view of an exemplary linear compressor according to an exemplary embodiment of the present invention is provided.

[0014] Figure 4 Provided Figure 3 A cross-sectional view of an exemplary linear compressor, illustrating the flow path.

[0015] Figure 5 An exemplary graph for experimental electric motor parameter estimation is provided.

[0016] Figure 6 An exemplary graph for experimental electric motor parameter estimation is provided.

[0017] Figure 7 A flowchart illustrating an exemplary embodiment of the present invention is provided. Detailed Implementation

[0018] Referring now to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is given by way of explanation and does not constitute a limitation thereof. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope. For example, features shown or described as part of one embodiment can be used in another embodiment, thereby producing yet another embodiment. Therefore, it is desired that the invention cover such modifications and variations falling within the scope of the appended claims and their equivalents.

[0019] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another, and these terms are not intended to indicate the location or importance of individual components. The terms “upstream” and “downstream” refer to the relative direction of fluid flow within a fluid pathway. For example, “upstream” refers to the direction from which the fluid flow originates, while “downstream” refers to the direction from which the fluid flow terminates. The term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”).

[0020] Now turn to the attached diagram. Figure 1 Describes the integration of a hermetically sealed refrigeration system 60 ( Figure 2 10. Refrigeration appliance. It should be understood that the term "refrigeration appliance" is used in a general sense herein to include refrigeration appliances of any kind, such as freezers, refrigerator / freezer combinations, and conventional refrigerators of any style or model. Furthermore, it should be understood that the invention is not limited to use in refrigeration appliances. Therefore, the invention can be used for any other suitable purpose, such as vapor compression in an air conditioning unit or air compression in an air compressor.

[0021] exist Figure 1 In the exemplary embodiment shown, the refrigeration appliance 10 is depicted as a vertical refrigerator having a cabinet or outer shell 12 defining a plurality of internal refrigerated storage compartments. Specifically, the refrigeration appliance 10 includes an upper food preservation compartment 14 with a door 16 and a lower freezer compartment 18 with an upper drawer 20 and a lower drawer 22. Drawers 20 and 22 are "pull-out" drawers because they can be manually moved in and out of the freezer compartment 18 via a suitable sliding mechanism.

[0022] Figure 2A schematic diagram of certain components of the refrigeration appliance 10 is provided, including the hermetically sealed refrigeration system 60 of the refrigeration appliance 10. Specifically, Figure 2 An exemplary oil cooling circuit with a sealed refrigeration system 60, according to an exemplary embodiment of the present invention, is provided. It should be understood that, unless otherwise indicated, in alternative exemplary embodiments, Figure 2 The exemplary oil cooling circuit can be modified or used in or with any suitable electrical appliance. For example, Figure 2 The exemplary oil cooling circuit can be used or used in conjunction with heat pump dryer appliances, heat pump water heater appliances, air conditioning appliances, etc.

[0023] The mechanical chamber 10 of the refrigeration appliance 10 may contain components for performing a known vapor compression cycle for cooling air. These components include a compressor 64, a condenser 66, an expander 68, and an evaporator 70 connected in series and filled with refrigerant. As those skilled in the art will understand, the refrigeration system 60 may include other components (e.g., at least one additional evaporator, compressor, expander, or condenser). As an example, the refrigeration system 60 may include two evaporators.

[0024] Within the refrigeration system 60, refrigerant typically flows into the compressor 64, whose operation increases the refrigerant pressure. This compression raises the refrigerant's temperature, which is lowered by passing the refrigerant through the condenser 66. Within the condenser 66, heat exchange occurs with the surrounding air to cool the refrigerant. A condenser fan 72 is used to blow air across the condenser 66 to provide forced convection for faster and more efficient heat exchange between the refrigerant within the condenser 66 and the surrounding air. Thus, as those skilled in the art will know, increasing the airflow through the condenser 66 can, for example, improve the efficiency of the condenser 66 by enhancing the cooling of the refrigerant contained therein.

[0025] An expansion device (e.g., a valve, capillary tube, or other throttling device) 68 receives refrigerant from the condenser 66. The refrigerant enters the evaporator 70 from the expansion device 68. As it leaves the expansion device 68 and enters the evaporator 70, the refrigerant pressure decreases. Due to this pressure drop or phase change, the evaporator 70 is cold relative 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 acts as a heat exchanger, transferring heat from the air passing through it to the refrigerant flowing through it.

[0026] In general, the vapor compression cycle components, associated fans, and associated compartments in the refrigeration circuit are sometimes referred to as operable to force cold air through compartments 14, 18 ( Figure 1 ( ) sealed refrigeration system. Figure 2The refrigeration system 60 described herein is provided by way of example only. Therefore, refrigeration systems using other constructions are also within the scope of this invention.

[0027] In some embodiments, an oil cooling circuit 200 of an exemplary embodiment of the present invention is shown together with a refrigeration system 60. The compressor 64 of the refrigeration system 60 may include or be disposed in a housing 302. Figure 3 Inside, the housing 302 also holds the lubricating oil. The lubricating oil helps reduce friction between the sliding or moving parts of the compressor 64 during operation. For example, when the piston slides within the cylinder to compress the refrigerant, the lubricating oil reduces friction between the piston and the cylinder of the compressor 64, a point that will be discussed in more detail below.

[0028] During the operation of compressor 64, the temperature of the lubricating oil may rise. Therefore, an oil cooling circuit 200 is provided to assist in dissipating the heat from the lubricating oil. By cooling the lubricating oil, the efficiency of compressor 64 can be improved. Thus, the oil cooling circuit 200 helps improve the efficiency of compressor 64 by lowering the temperature of the lubricating oil within compressor 64, for example, compared to a compressor without the oil cooling circuit 200.

[0029] In an optional embodiment, the oil cooling circuit 200 includes a heat exchanger 210 spaced apart from at least a portion of the compressor 64. A lubricating oil conduit 220 extends between the compressor 64 and the heat exchanger 210. Lubricating oil from the compressor 64 can flow to the heat exchanger 210 via the lubricating oil conduit 220. Figure 2 As shown, the lubricating oil conduit 220 may include a supply conduit 222 and a return conduit 224. The supply conduit 222 extends between the compressor 64 and the heat exchanger 210 and is configured to guide lubricating oil from the compressor 64 to the heat exchanger 210. Conversely, the return conduit 224 extends between the heat exchanger 210 and the compressor 64 and is configured to guide lubricating oil from the heat exchanger 210 to the compressor 64.

[0030] Within the heat exchanger 210, the lubricating oil dissipates heat to the ambient air surrounding the heat exchanger 210. The lubricating oil flows from the heat exchanger 210 back to the compressor 64 via the lubricating oil conduit 220. Thus, the lubricating oil conduit 220 allows the lubricating oil to circulate between the compressor 64 and the heat exchanger 210, and the heat exchanger 210 can reduce the temperature of the lubricating oil from the compressor 64 before returning it to the compressor 64. Consequently, the oil cooling circuit 200 can remove the lubricating oil from the compressor 64 via the lubricating oil conduit 220 after cooling it in the heat exchanger 210, and then return the lubricating oil to the compressor 64 via the lubricating oil conduit 220.

[0031] In some embodiments, heat exchanger 210 is disposed at or adjacent to fan 72. For example, heat exchanger 210 may be configured and oriented such that fan 72 draws or pushes air through heat exchanger 210 to provide forced convection for faster and more efficient heat exchange between the lubricating oil within heat exchanger 210 and the ambient air surrounding refrigeration system 60. In some exemplary embodiments, heat exchanger 210 may be arranged between fan 72 and condenser 66. Thus, heat exchanger 210 may be positioned downstream of fan 72 and upstream of condenser 66 relative to the airflow from fan 72. In this way, air from fan 72 can exchange heat with the lubricating oil in heat exchanger 210 before exchanging heat with the refrigerant in condenser 66.

[0032] In another or alternative embodiment, heat exchanger 210 is disposed at or on condenser 66. For example, heat exchanger 210 may be mounted to condenser 66 such that heat exchanger 210 and condenser 66 are in conductive thermal communication with each other. Thus, condenser 66 and heat exchanger 210 can exchange heat conductively. In this way, heat exchanger 210 and condenser 66 can provide heat exchange between lubricating oil in heat exchanger 210 and refrigerant in condenser 66.

[0033] In some exemplary embodiments, heat exchanger 210 may be a tube-to-tube heat exchanger 210 integrated within or on condenser 66 (e.g., a portion of condenser 66). For example, heat exchanger 210 may be soldered or tin-bonded to condenser 66. In alternative embodiments, heat exchanger 210 may be arranged on a portion of condenser 66 between the inlet and outlet of condenser 66. For example, refrigerant may enter condenser 66 at the inlet of condenser 66 at a first temperature (e.g., 150 degrees Fahrenheit (150°F)), and heat exchanger 210 may be positioned on condenser 66 downstream of the inlet of condenser 66 such that refrigerant immediately upstream of the portion of condenser 66 where heat exchanger 210 is mounted may have a second temperature (e.g., 90 degrees Fahrenheit (90°F)).

[0034] The heat exchanger 210 can also be located upstream of the outlet of the condenser 66, such that the refrigerant downstream of the portion of the condenser 66 where the heat exchanger 210 is installed can have a third temperature (e.g., 150 degrees Fahrenheit (105°F)) and can exit the condenser 66 at the outlet at a fourth temperature (e.g., 90 degrees Fahrenheit (90°F)). Thus, during operation of the compressor 64, the refrigerant within the condenser 66 can have its temperature increased at the portion of the condenser 66 where the heat exchanger 210 is installed, in order to cool the lubricating oil within the heat exchanger 210. However, the portion of the condenser 66 downstream of the heat exchanger 210 can assist in dissipating heat to the ambient air surrounding the condenser 66.

[0035] Turn now Figure 3 and Figure 4 Various cross-sectional views of a linear compressor 300 according to 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 a fluid within the chamber 312 of the linear compressor 300. The linear compressor 300 can be used to compress any suitable fluid, such as a refrigerant. In particular, the linear compressor 300 can be used in refrigeration appliances, such as the linear compressor 300 can be used as compressor 64 ( Figure 2 10 ( ) refrigeration appliances Figure 1 ). For example in Figure 3 As can be seen, the linear compressor 300 defines an axial direction A and a radial direction R. The linear compressor 300 can be enclosed within an airtight or hermetically sealed housing 302. In other words, the linear compressor 300 can be enclosed within an internal volume 303 defined by the housing 302. For example, the linear compressor can be supported within the internal volume 303 by one or more mounting springs 305, which can substantially dampen the oscillation or movement of the linear compressor 300 relative to the housing 302. When assembled, the airtight housing 302 impedes or prevents refrigerant or lubricating oil from leaking or overflowing from the refrigeration system 60. Figure 2 ).

[0036] The linear compressor 300 includes a housing 308 extending between a first end 304 and a second end 306 (e.g., along axial direction A). The housing 308 includes various relatively stationary or non-moving structural components of the linear compressor 300. Specifically, the housing 308 includes a cylinder assembly 310 defining a chamber 312. The cylinder assembly 310 may be located at or adjacent to the second end 306 of the housing 308. The chamber 312 may extend longitudinally along axial direction A.

[0037] 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 the end of the chamber 312) that allow refrigerant to enter and exit the chamber 312 during operation of the linear compressor 300.

[0038] In some embodiments, the discharge valve assembly 320 is mounted to the housing 308 (e.g., at the second end 306). The discharge valve assembly 320 may include a muffler housing 322, a valve head 324, and a valve spring 338.

[0039] The muffler housing 322 may include an end wall 326 and a cylindrical side wall 328. The cylindrical side wall 328 is mounted to the end wall 326 and extends from the end wall 326 (e.g., along axial direction A) to the cylinder assembly 310 of the housing 308. A refrigerant outlet conduit 330 may extend from or through the muffler housing 322 and through the housing 302 (e.g., to the condenser 66-). Figure 2 (or in fluid communication with it) to selectively allow refrigerant to flow out from the discharge valve assembly 320 during operation of the linear compressor 300.

[0040] The muffler housing 322 can be mounted or secured to the housing 308, and other components of the discharge valve assembly 320 can be arranged within the muffler housing 322. For example, a plate 332 of the muffler housing 322 at the distal end of the cylindrical sidewall 328 can be disposed at or on the cylinder assembly 310, and a seal (e.g., an O-ring or gasket) can extend between the cylinder assembly 310 and the plate 332 of the muffler housing 322 (e.g., along axial direction A) to limit fluid leakage at the axial gap between the housing 308 and the muffler housing 322. Fasteners can extend through the plate 332 into the housing 308 to mount the muffler housing 322 to the housing 308.

[0041] In some embodiments, the valve head 324 is located at or adjacent to the chamber 312 of the cylinder assembly 310. The valve head 324 may selectively cover a passage extending through the cylinder assembly 310 (e.g., along axial direction A). This passage may be continuous with the chamber 312. During assembly, a valve spring 338 may be coupled to the muffler housing 322 and the valve head 324. The valve spring 338 may be configured to push the valve head 324 toward or against the cylinder assembly 310 (e.g., along axial direction A).

[0042] A piston assembly 316 with a piston head 318 can be slidably received within a chamber 312 of a cylinder assembly 310. Specifically, the piston assembly 316 can slide along an axial direction A within the chamber 312. During the sliding 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 can slide along an axial direction A towards a bottom dead center position within the chamber 312 from a top dead center position (i.e., the 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 towards the top dead center position within the chamber 312 (i.e., the compression stroke of the piston head 318). An expansion valve assembly 320 can open along with or immediately before the piston head 318 reaches the top dead center position. For example, a valve head 324 can be pushed away from the cylinder assembly 310, which allows refrigerant to exit from the chamber 312 and flow through the discharge valve assembly 320 to the refrigerant outlet conduit 330.

[0043] It should be understood that the linear compressor 300 may include additional piston heads or additional chambers at opposite ends of the linear compressor 300 (e.g., near the first end 304). Thus, in an alternative exemplary embodiment, the linear compressor 300 may have multiple piston heads.

[0044] In some embodiments, the linear compressor 300 includes an inner back iron assembly 352. The inner back iron assembly 352 is disposed within the stator of the motor. Specifically, an outer back iron 364 or drive coil 366 may extend around the inner back iron assembly 352 (e.g., circumferentially). 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., mounted on the outer surface of the inner back iron assembly 352). The drive magnet 362 may face or be exposed to the drive coil 366. Specifically, 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 can 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 can be inserted into the inner back iron assembly 352. Thus, during the 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.

[0045] As in Figure 3As can be seen, the drive coil 366 can extend around the inner back iron assembly 352 (e.g., circumferentially). Typically, 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 connected to a controller 367) can induce a current in the drive coil 366 to generate a magnetic field that attracts the drive magnet 362 and pushes the piston assembly 316 along the axial direction A to compress the refrigerant within the chamber 312 as described above. Specifically, during operation of the drive coil 366, the magnetic field of the drive coil 366 can 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 can cause the piston assembly 316 to slide between the top dead center position and the bottom dead center position.

[0046] In an alternative embodiment, the linear compressor 300 includes various components for allowing and / or regulating the operation of the linear compressor 300. Specifically, the linear compressor 300 includes a controller 367 configured to regulate the operation of the linear compressor 300. The controller 367 is operatively in communication with a motor (e.g., a drive coil 366 of the motor). Thus, the controller 367 can selectively activate the drive coil 366, for example, 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 understood, such a control loop can regulate the supply voltage of the supplied current (e.g., peak voltage or root mean square (RMS) voltage) to a desired reference voltage. For this purpose, 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).

[0047] Controller 367 includes memory and one or more processing devices, such as a microprocessor, CPU, etc., such as a general-purpose or special-purpose microprocessor, operable to execute programming instructions or microcontroller code related to the operation of linear compressor 300. The memory may represent random access memory such as DRAM or 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, controller 367 may be constructed to perform control functions without using 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.

[0048] The linear compressor 300 also includes one or more spring assemblies 340, 342 mounted to the housing 308. In some embodiments, a pair of spring assemblies (i.e., a first spring assembly 340 and a second spring assembly 342) restrict the drive coil 366 along the axial direction A. In other words, the first spring assembly 340 is positioned near a first end 304, and the second spring assembly 342 is positioned near a second end 306.

[0049] In some embodiments, each spring assembly 340 and 342 includes one or more planar springs mounted or fixed to each other. In particular, the planar springs may be mounted or fixed to each other such that the respective planar springs of the corresponding assembly 340 or 342 are spaced apart from each other (e.g., along axial direction A).

[0050] Typically, the spring assemblies 340, 342 assist in connecting the inner back iron assembly 352 to the housing 308. In some such embodiments, a first outer fastener 344 (e.g., bolt, nut, clamp, lug, weld, solder, etc.) secures the first spring assembly 340 and the second spring assembly 342 to the housing 308 (e.g., a stator support), while a first inner fastener 346, radially inward from the first outer fastener 344 (e.g., along the vertical radial direction R near the axial direction A), secures the first spring assembly 340 to the inner back iron assembly 352 at a first end 304. In another or alternative embodiment, a second inner fastener 350, radially inward from the first outer fastener 344 (e.g., along the radial direction R near the axial direction A), secures the second spring assembly 342 to the inner back iron assembly 352 at a second end 306.

[0051] During the operation of the drive coil 366, spring assemblies 340 and 342 support the inner back iron assembly 352. Specifically, the inner back iron assembly 352 is suspended within the stator or motor of the linear compressor 300 by the spring assemblies 340 and 342, such that the movement of the inner back iron assembly 352 along the radial direction R is inhibited or restricted, while its movement along the axial direction A is relatively unimpeded. Thus, the spring assembly 342 can be stiffer along the radial direction R than along the axial direction A. In this way, during the operation of the motor and the movement of the inner back iron assembly 352 in the axial direction A, the spring assemblies 340 and 342 can (e.g., along the radial direction R) help maintain the uniformity of the air gap between the drive magnet 362 and the drive coil 366. The spring assemblies 340 and 342 also help prevent the lateral pull of the motor from being transmitted to the piston assembly 316 and reacting as frictional loss in the cylinder assembly 310.

[0052] In an optional embodiment, the inner back iron assembly 352 includes an outer cylinder 354 and a sleeve 360. The sleeve 360 ​​is disposed on or on the inner surface of the outer cylinder 354. A first interference fit between the outer cylinder 354 and the sleeve 360 ​​can connect or secure the outer cylinder 354 and the sleeve 360 ​​together. In an optional exemplary embodiment, the sleeve 360 ​​can be welded, glued, fastened, or attached to the outer cylinder 354 via any other suitable mechanism or method.

[0053] During assembly, sleeve 360 ​​may extend about axial direction A (e.g., along the circumferential direction). In an exemplary embodiment, a first interference fit between outer cylinder 354 and sleeve 360 ​​connects or secures outer cylinder 354 and sleeve 360 ​​together. In an alternative exemplary embodiment, sleeve 360 ​​may be welded, glued, fastened, or attached to outer cylinder 354 via any other suitable mechanism or method. As shown, sleeve 360 ​​extends within outer cylinder 354 (e.g., along axial direction A) between a first end 304 and a second end 306 of inner back iron assemblies 352, 130. First spring assembly 340 and second spring assembly 342 are mounted to sleeve 360 ​​(e.g., using inner fasteners 346 and 350).

[0054] The outer cylinder 354 can be constructed from or using any suitable material. For example, the outer cylinder 354 can be constructed from or using multiple (e.g., ferromagnetic) laminations. The laminations are distributed circumferentially to form the outer cylinder 354 and are mounted to each other or fixed together (e.g., using rings pressed onto the ends of the laminations). The outer cylinder 354 defines a recess extending inward from the outer surface of the outer cylinder 354 (e.g., along radial R). A drive magnet 362 can be disposed in the recess on the outer cylinder 354 (e.g., such that the drive magnet 362 is inserted into the outer cylinder 354).

[0055] In some embodiments, the piston flexible mount 368 is mounted to and extends through the inner back iron assembly 352. Specifically, the piston flexible mount 368 is mounted to the inner back iron assembly 352 via a sleeve 360 ​​and spring assemblies 340, 342. Thus, the piston flexible mount 368 can be coupled (e.g., threaded) to the sleeve 360 ​​to mount or secure the piston flexible mount 368 to the inner back iron assembly 352. A coupling 370 extends between the piston flexible mount 368 and the piston assembly 316 (e.g., along axial direction A). The coupling 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 axial direction A) is transmitted to the piston assembly 316. The coupling 370 can extend through a drive coil 366 (e.g., along axial direction A).

[0056] The piston flexible mount 368 may define at least one passage 369. The passage 369 (e.g., along axial direction A) extends through the piston flexible mount 368. Thus, during operation of the linear compressor 300, a fluid flow such as air or refrigerant can pass through the piston flexible mount 368 via the passage 369. As shown, one or more refrigerant inlet conduits 331 may extend through the housing 302 to allow refrigerant to enter from the evaporator 70 (or another part of the sealing system 60)... Figure 2 Return to compressor 300.

[0057] The piston head 318 also defines at least one opening (e.g., selectively covered by a head valve). The opening of the piston head 318 (e.g., along axial direction A) extends through the piston head 318. Thus, during operation of the linear compressor 300, a refrigerant flow can pass through the opening of the piston head 318 into the chamber 312. In this way, a fluid flow (compressed within the chamber 312 by the piston head 318) can flow through the piston flexible mount 368 and the inner back iron assembly 352 to the piston assembly 316.

[0058] As shown in the figure, the linear compressor 300 may include a system for guiding oil through the linear compressor 300 and an oil cooling circuit 200. Figure 2 Features of the oil cooler circuit 200. One or more inlet pipes 380 or outlet pipes 382 may extend through the housing 302 to guide oil to / from the oil cooler circuit 200.

[0059] Optionally, the oil inlet pipe 380 can be connected to the oil cooling circuit 200. Figure 2 The return pipe 224 is used for lubricating oil. Thus, lubricating oil can flow from the heat exchanger 210 to the linear compressor 300 via the oil inlet pipe 380. Optionally, the oil inlet pipe 380 can be located at or adjacent to the reservoir 376. Thus, lubricating oil from the oil inlet pipe 380 to the linear compressor 300 can flow into the reservoir 376. As described above, the oil cooling circuit 200 can cool the lubricating oil from the linear compressor 300. After this cooling, the lubricating oil returns to the linear compressor 300 via the oil inlet pipe 380. Thus, the lubricating oil in the oil inlet pipe 380 can be relatively cool, and it also helps cool the lubricating oil in the reservoir 376.

[0060] In some embodiments, the linear compressor 300 includes a pump 372. The pump 372 may be located at or adjacent to a reservoir 376 within the housing 302 (e.g., within the pump housing 374). The reservoir 376 corresponds to a portion of the housing 302 located at or adjacent to the bottom of the housing 302. Thus, a certain volume of lubricating oil 377 within the housing 302 can accumulate in the reservoir 376 (e.g., because the lubricating oil is denser than the refrigerant within the housing 302). During operation, the pump 372 can draw lubricating oil 377 from the volume within the reservoir 376 to the pump 372 via a supply conduit 378 extending from the pump 372 to the reservoir 376. For example, a pair of check valves within the pump housing 374 at opposite ends of the pump 372 can selectively allow oil to flow into / from the pump housing 374 as the pump 372 oscillates within the pump housing 374 (e.g., driven by oscillations of the housing 308). Alternatively or concurrently, when the pump 372 actively oscillates, the volume of the lubricating oil 377 can be maintained at a predetermined level (e.g., even at the vertical midpoint of the pump 372).

[0061] Internal conduit 384 can extend from pump 372 (e.g., pump housing 374) to oil reservoir 386 defined within housing 308. In some embodiments, oil reservoir 386 is disposed radially outward from chamber 312 of cylinder assembly 310. For example, oil reservoir 386 may be defined to extend in a circumferential direction (e.g., around axial direction A) as an annular chamber surrounding chamber 312 of cylinder assembly 310.

[0062] Typically, lubricating oil can be selectively directed from the reservoir 386 to the cylinder assembly 310. Specifically, one or more channels (e.g., radial channels) can extend from the reservoir 386 to the chamber 312. Such radial channels 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 axial direction A). As the piston head 318 slides within the chamber 312, the sidewalls of the piston head 318 can receive lubricating oil. In an alternative embodiment, the radial channel terminates at a recess 388 defined by the cylinder assembly 310 within the chamber 312. Thus, the recess 388 can open into the chamber 312. Lubricating oil from the reservoir 386 can flow into the chamber 312 of the cylinder assembly 310 (e.g., via the radial channel to the recess 388) to lubricate the movement of the piston assembly 316 within the chamber 312 of the cylinder assembly 310.

[0063] The housing 308 may define an oil drain port 390 together with the chamber 312 and the oil reservoir 386. In some embodiments, the oil drain port 390 extends from the oil reservoir 386. For example, the oil drain port 390 may extend outward from the oil reservoir 386 through the housing 308. Thus, the oil drain port 390 may be in fluid communication with the oil reservoir 386. During use, at least a portion of the lubricating oil propelled to the oil reservoir 386 may flow to the oil drain port 390 (e.g., as propelled by the pump 372). The lubricating oil may exit the housing 308 (typically and the linear compressor 300) from the oil drain port 390. In some embodiments, the oil drain port 390 is in fluid communication with an oil outlet conduit 382. Thus, the pump 372 may typically propell lubricating oil from the internal volume 303 through the housing 308 to the oil outlet conduit 382. The oil outlet conduit 382 may be connected to an oil cooling circuit 200 ( Figure 2 The supply pipe 222 is used to supply lubricating oil. Pump 372 can then push lubricating oil from reservoir 376 into supply pipe 222. In this way, pump 372 can supply lubricating oil to oil cooling circuit 200 to cool the lubricating oil from linear compressor 300, as described above.

[0064] Separate from or excluding the drain port 390, the housing 308 may define a gas vent 392. Specifically, the gas vent 392 extends from the reservoir 386 through to the internal volume 303. As shown, the gas vent 392 is defined fluid-parallel to the drain port 390. Thus, fluid is directed separately through both the gas vent 392 and the drain port 390. Typically, the gas vent 392 can be sized to restrict fluid flow more than the drain port 390. For example, the minimum diameter of the gas vent 392 can still be smaller than the minimum diameter of the drain port 390. Optionally, the minimum diameter of the gas vent 392 can be less than two millimeters, while the minimum diameter of the drain port is greater than four millimeters. In addition to a smaller diameter, the length of the gas vent 392 can also be shorter than the length of the drain port 390. Under typical pumping operation, a greater amount of lubricating oil can pass through the drain port 390 than through the gas vent 392. However, it is permissible to allow gas (e.g., generated during the venting process within the reservoir 386) to enter the internal volume 303 through the gas outlet 392, while allowing continuous flow of lubricating oil from the reservoir 386 to the outlet 390 or chamber 312.

[0065] Gas vent 392 may be defined at the upper portion of housing 308 (e.g., the upper end of reservoir 386). Alternatively, gas vent 392 may extend above drain valve assembly 320 (e.g., parallel to axial direction A). Gas vent 392 may also be located below drain port 390 (e.g., lower than drain port 390 along vertical direction V). In some embodiments, gas vent 392 is located at a second end 306 of housing 308. Fluid from gas vent 392 may be directed forward into internal volume 303.

[0066] 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 arranged on the housing 308 (e.g., at the second end 306). A dripping channel may be defined between the oil shield 394 and, for example, the muffler housing 322. For example, the oil shield 394 may extend outward from the housing 308 to a curved or inwardly extending wall portion 396. Alternatively or additionally, the oil shield 394 may extend around a portion of the muffler housing 322. For example, the oil shield 394 may extend 180° along the top side of the muffler housing 322. During use, lubricating oil discharged through the gas discharge port 392 may be guided downward to the reservoir 376. During use, the oil shield 394 may prevent lubricating oil from impacting the housing 302 (e.g., impacting at high speed, which would otherwise cause atomization of the lubricating oil within the internal volume 303).

[0067] Turn now Figure 5 and Figure 6 When using a linear compressor (e.g., linear compressor 300- Figure 3 During this period, the linear compressor may suddenly shift or be unintentionally struck, such as when the corresponding appliance (e.g., refrigeration appliance 10-) is in contact with the compressor. Figure 1 When the door of a linear compressor slams shut, this displacement or impact can cause the compressor to repeatedly collide with the enclosed casing. For example, regarding... Figure 3 In an exemplary embodiment, the muffler housing 328 may collide with the inner surface of the housing 302. This internal collision may repeat when the linear compressor 300 oscillates or vibrates on the support spring 305.

[0068] Figure 5 and Figure 6 A pair of exemplary diagrams are provided, illustrating the changes in experimental motor parameter estimates obtained during an internal collision event, and the resulting changes in one or more control parameters (e.g., a reference current according to the disclosed operating method). Specifically, Figure 5 An example is given of the detection line LS and the reference line LR over a time span (e.g., measured in seconds or according to the discrete electrical cycles of the motor).Figure 6 Examples are provided for the variance line LV and variance threshold line LT calculated over the same time span.

[0069] Typically, the detection line LS plots the change of the detected supply current (e.g., at or to the motor of the linear compressor 300) over time. The reference line LR plots the change of a reference current over time, which can be used as a control parameter for the control loop of the motor of the linear compressor 300 (e.g., adjusted in response to changes in the detected supply current). The calculated variance line LV plots the change of the variance value calculated from the values ​​of the detection lines over time. Typically, the variance threshold can be kept constant (e.g., as a predetermined value), thus the variance threshold line LT is flat over time. As will be described in detail below, the value of the reference current can be changed based on (e.g., in response to) one or more determinations that one or more calculated variance values ​​exceed the variance threshold. It is worth noting that the change of the reference current can be independent of the piston's position within the linear compressor (e.g., making it possible to detect internal impacts without prohibiting separate monitoring sequences used to determine hard or soft impacts of the piston within the motor). Note that although the detected supply current value, reference current value, and calculated variance value are exemplified as peak current values, another suitable current value (e.g., RMS) can be used similarly.

[0070] Now go to Figure 7 The example illustrates an exemplary method of operating a linear compressor (e.g., method 700). As will be understood in light of the invention, such a method can be applied to any suitable linear compressor (e.g., linear compressor 300) to detect or correct internal collisions between the linear compressor and the enclosed housing (e.g., housing 302). In some embodiments, the methods described below can be initiated or directed by a controller 367 (e.g., as a software program configured to be initiated by the controller 367 or as part of a software program).

[0071] Advantageously, the method described herein allows the corresponding linear compressor to quickly detect or mitigate internal collisions between the linear compressor and the inner surface of the surrounding housing. Additionally or alternatively, this method can be advantageously performed without requiring additional or detected sensor components.

[0072] In 710, method 700 includes driving the motor of the linear compressor to a reference current. For example, as described above, a variable reference current can be used to induce current in the drive coil of the motor and drive the piston to move within the linear compressor. Moreover, the motor can be driven in a generally continuous or uninterrupted manner, such that 710 extends over multiple electrical cycles (e.g., represented on a sine wave of current, as will be understood).

[0073] Typically, the motor can be driven based on any suitable reference current control loop. As an example, a supply voltage can be directed to the motor to start it. The supply voltage can 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 a reference current (e.g., reference peak current or reference RMS current). The sampled current can be measured or estimated using any suitable method or mechanism. For example, an ammeter can be used to measure the sampled current as the peak current. The voltage selector of the controller can operate as a proportional-integral (PI) controller to reduce the error between the sampled current and the reference current. At the beginning of 710, the reference current can be a default value (e.g., a default peak current value or peak RMS value), which can then be adjusted (e.g., increased or decreased) during subsequent steps of method 700, as discussed in more detail below, such that method 700 returns to (or otherwise continues) driving the motor 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.

[0074] At 720, method 700 includes detecting a sampled current during 710. In other words, when the motor is driven, the current supplied to the motor can be sampled (e.g., as a peak supply current value or an RMS current value). In some embodiments, 720 includes detecting discrete sampled values ​​over time. Thus, as the motor continues to be driven, sampled values ​​of the motor's supply current can continue to be detected. In alternative embodiments, discrete sampled current values ​​are detected for each electrical cycle. Thus, at least one sampled value can be obtained for a corresponding electrical cycle. For example, the sampled value can be detected by detecting the maximum current during each electrical cycle. Additionally or alternatively, the sampled current value may include the absolute value of the maximum current for each corresponding electrical cycle, such that the sampled current value is detected based on the amplitude of the supply current.

[0075] In some implementations, 720 may include detecting a predetermined number of groups of sampled current values. For example, the group may include a window of sequential current values ​​to be stored in the controller. Thus, when a new sampled current value is detected, it can be stored within the group or window. This can continue until the group or window is full (i.e., a predetermined number of sampled current values ​​have been obtained). Alternatively, the group or window may be a scrolling group, such that a new sampled current value can replace the oldest previously sampled current value within the group.

[0076] In 730, method 700 includes calculating the variance of the current using the sampled current. The calculated variance can be a recursive variance, and thus represents the sampled current value detected over time (e.g., over multiple electrical cycles, even when no previous sampled current value is held or stored in memory). Typically, the sampled current can be used in a programmed variance formula. Such a variance formula is known, and a programmed variance formula can be provided as or include this variance formula. As an example, the programmed variance formula (Var(X)) can be or includes:

[0077]

[0078] Where xi is the detected sampled current value, n is the number of samples for calculating the variance of the current, and μ is the average value of xi (e.g., calculated as a rolling average, moving average, weighted average, etc.). Optionally, the variance of the current can be calculated from a predetermined number of groups. In some such embodiments, n is a predetermined number, and the values ​​of the predetermined number of groups are used for the sample xi. Thus, 730 may include calculating the average of the predetermined number of sampled current values.

[0079] Optionally, 730 may include calculating the variance of the current based on the change (ΔX) in the sampled value. Thus, 730 may include: calculating the difference between the previously sampled current and the sampled current (i.e., the current sampled current); and calculating the variance of the current based on the difference between the previously sampled current and the sampled current. As an example, the programmed variance formula may be or include:

[0080]

[0081] Δxi is a sample of the differences between the calculated sampled current values, n is the number of samples for calculating the variance of the current, and μ is the average value of Δxi (e.g., calculated as a rolling average, moving average, weighted average, etc.). Advantageously, it can prevent abnormal variance variations between individual sampled current values ​​from affecting large variations in any control parameters based on the calculated variance.

[0082] At 740, method 700 includes determining that the calculated variance exceeds a variance threshold. For example, the calculated variance value at 730 can be compared with a predetermined variance threshold (e.g., a current peak threshold or a current RMS value), and it can be determined that the calculated variance value at 730 is greater than the variance threshold. Optionally, this can be repeated, such that multiple (e.g., sequential) calculated current variance values ​​can be determined to exceed the variance threshold.

[0083] At 750, method 700 includes limiting the reference current based on 740. Specifically, in response to one or more determinations that the calculated variance exceeds a variance threshold, the reference current used to drive the motor can be reduced. This can be done independently of the piston position of the motor (e.g., as described above).

[0084] Optionally, the reduction may be to reduce the reference current (e.g., the reference current value at a certain time of 740) by a predetermined reduction value. Alternatively or optionally, a reduction formula may be provided to variably reduce the reference current (e.g., based on the magnitude of the reference current value at a certain time of 740).

[0085] In some implementations, 750 requires that the calculated variance repeatedly exceed a variance threshold. Thus, 750 may depend on determining that multiple calculated variance values ​​exceed a predetermined variance (e.g., through a prompt). In some such implementations, multiple calculated variance values ​​may require that the number of groups (e.g., counts or instances) of calculated variances exceed a variance threshold. Additionally or alternatively, it may be required that all determinations occur within a set number of time periods or cycles.

[0086] After limiting the reference current, the limited or reduced reference current can be used to drive the motor. If subsequent electrical cycles (e.g., a set number of cycles or a predetermined time period) pass without the calculated variance exceeding a further determined variance threshold, the reference current can be increased (e.g., incrementally) until the adjusted reference current equals the default reference current value (or another predetermined reference current value).

[0087] This written description discloses the invention using examples (including preferred embodiments) and enables those skilled in the art to practice the invention (including making and using any apparatus or system and performing any of the included methods). The patentable scope of the invention is defined by the claims and may include other examples that may be conceived by those skilled in the art. Such other examples are expected to fall within the scope of the claims if they include structural elements that are not distinct from the literal language of the claims, or if they include equivalent structural elements that are not substantially distinct from the literal language of the claims.

Claims

1. A method for operating a linear compressor to correct internal collisions between the linear compressor and the casing enclosing the linear compressor, characterized in that, The method includes: Drive the motor of the linear compressor to the reference current; The sampled current is detected during the driving of the motor; The variance of the current is calculated using the sampled current; Determine that the variance of the calculated current exceeds a variance threshold; and The reference current is limited based on the determination that the variance of the calculated current exceeds the variance threshold; In response to the variance of one or more calculated currents exceeding a variance threshold, the reference current used to drive the motor is reduced, which is done independently of the piston position of the motor; after limiting the reference current, the reduced reference current is used to drive the motor; if subsequent electrical cycles pass without the variance of the calculated current exceeding the variance threshold, the reference current is increased until the adjusted reference current equals the default reference current value.

2. The method according to claim 1, characterized in that, The sampled current includes a peak supply current value, and the reference current includes a reference peak current value.

3. The method according to claim 1, characterized in that, The sampled current includes a root mean square current value, and the reference current includes a reference root mean square current value.

4. The method according to claim 1, characterized in that, The variance of the calculated current is the recursive variance.

5. The method according to claim 1, characterized in that, The variance of the current is calculated as follows: Calculate the difference between the previously sampled current and the sampled current; and The variance of the current is calculated based on the difference between the previously sampled current and the sampled current.

6. The method according to claim 1, characterized in that, Detecting the sampled current includes detecting a predetermined number of sampled current values, and wherein calculating the variance of the current includes calculating the variance of the predetermined number of sampled current values.

7. The method according to claim 6, characterized in that, Calculating the variance of the current involves calculating the average of the sampled current values ​​from the predetermined number of groups.

8. The method according to claim 1, characterized in that, Determining that the variance of the calculated current exceeds the variance threshold includes determining that the variance values ​​of a plurality of calculated currents exceed the variance threshold, and wherein limiting the reference current depends on determining that the variance values ​​of the plurality of calculated currents exceed the variance threshold.

9. A method for operating a linear compressor to correct internal collisions between the linear compressor and the casing enclosing the linear compressor, characterized in that, The method includes: The motor of the linear compressor is driven to a reference current during multiple electrical cycles; Detecting the sampled current includes detecting discrete sampled current values ​​for each of the plurality of electrical cycles; The variance of the current is calculated using the sampled current; Determine that the variance of the calculated current exceeds a variance threshold; and The piston position, independent of the motor, limits the reference current based on determining that the variance of the calculated current exceeds the variance threshold; In response to the variance of one or more calculated currents exceeding a variance threshold, the reference current used to drive the motor is reduced, which is done independently of the piston position of the motor; after limiting the reference current, the reduced reference current is used to drive the motor; if subsequent electrical cycles pass without the variance of the calculated current exceeding the variance threshold, the reference current is increased until the adjusted reference current equals the default reference current value.

10. The method according to claim 9, characterized in that, The sampled current includes a peak supply current value, and the reference current includes a reference peak current value.

11. The method according to claim 9, characterized in that, The sampled current includes a root mean square current value, and the reference current includes a reference root mean square current value.

12. The method according to claim 9, characterized in that, The variance of the calculated current is a recursive variance.

13. The method according to claim 9, characterized in that, The variance of the current is calculated as follows: Calculate the difference between the previously sampled current and the sampled current; and The variance of the current is calculated based on the difference between the previously sampled current and the sampled current.

14. The method according to claim 9, characterized in that, The sampled current value is the absolute value of the maximum current of the corresponding electrical cycle.

15. The method according to claim 9, characterized in that, Detecting the sampled current includes detecting a predetermined number of sampled current values, and wherein calculating the variance of the current includes calculating the variance of the predetermined number of sampled current values.

16. The method according to claim 15, characterized in that, Calculating the variance of the current involves calculating the average of the sampled current values ​​from the predetermined number of groups.

17. The method according to claim 9, characterized in that, Determining that the variance of the calculated current exceeds the variance threshold includes determining that the variance values ​​of a plurality of calculated currents exceed the variance threshold, and wherein limiting the reference current depends on determining that the variance values ​​of the plurality of calculated currents exceed the variance threshold.

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