Linear compressor having self-aligning coupler

Abstract

A linear compressor (100) having a self-aligning coupler (200), comprising a drive coil (122), a mover, a piston (130) and the coupler (200). The mover is adjacent to the drive coil (122). The drive coil (122) is operable to enable the mover to reciprocate relative to the drive coil (122). The piston (130) has a piston head (132) and a cylindrical side wall (134), an inner surface (138) of the cylindrical sidewall (134) defining a ball socket (139). The coupler (200) extends between the mover and the piston (130), and the coupler (200) comprises a flexible mounting member (210) and a ball head (220).

Description

Linear compressor with self-aligning coupling CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. application No. 18 / 428,735, filed on January 31, 2024, the entirety of which is incorporated herein by reference. Technical Field

[0002] The present application generally relates to a linear compressor and a coupling for a linear compressor. Background Art

[0003] Some recent refrigeration systems are equipped with linear compressors for compressing refrigerant. These compressors typically consist of a piston and a drive coil. The drive coil generates a force that causes the piston to slide back and forth within a cavity. As the piston moves within the cavity, it compresses the refrigerant. However, if the piston is not properly aligned within the cavity, friction between the piston and the cavity walls can negatively impact the operation of the linear compressor. In particular, friction losses caused by friction between the piston and the cavity walls can negatively impact the efficiency of the refrigeration system.

[0004] It would therefore be useful for a linear compressor to have the ability to limit friction between the piston and the cylinder wall during operation. Summary of the Invention

[0005] Various aspects and advantages of the present application 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 present application.

[0006] In one exemplary aspect of the present application, a linear compressor is provided. The linear compressor may include a drive coil, a mover, a piston, and a coupling. The mover may be disposed adjacent to the drive coil. The drive coil may be operable to reciprocate the mover relative to the drive coil. The piston may have a piston head and a cylindrical sidewall. The inner surface of the cylindrical sidewall may define a ball seat. The coupling may extend between the mover and the piston. The coupling may include a flexible mount, a ball head, and a freeze ring. The flexible mount may extend between a first end and a second end. The flexible mount may be connected to the mover at a position distal to the first end of the flexible mount. The ball head may be located at the first end of the flexible mount. The ball head may contact the piston at the ball seat of the piston. The freeze ring may be disposed radially inward from the ball head at the first end of the flexible mount to guide its variable axial alignment.

[0007] In another exemplary aspect of the present application, a linear compressor is provided. The linear compressor may include a drive coil, a mover, a piston, and a coupling. The mover may be disposed adjacent to the drive coil. The drive coil may be operable to cause the mover to reciprocate relative to the drive coil. The piston may have a piston head and a cylindrical sidewall. The inner surface of the cylindrical sidewall may define a ball seat. The coupling may extend between the mover and the piston. The coupling may include a flexible mounting member and a ball head. The flexible mounting member may extend between a first end and a second end. The flexible mounting member may be connected to the mover at a position distal to the first end of the flexible mounting member. The flexible mounting member may form a truncated conical edge at the first end. The ball head may be located at the first end of the flexible mounting member, in contact with the truncated conical edge. The ball head may further contact the piston at the ball seat of the piston.

[0008] These and other features, aspects and advantages of the present application will be better understood with reference 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 present application and, together with the description, serve to explain the principles of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] This application, including the best mode thereof, is a full and enabling disclosure to those skilled in the art that is set forth in the specification with reference to the accompanying drawings.

[0010] FIG. 1 is a front view of a refrigerator apparatus according to an exemplary embodiment of the present application.

[0011] FIG. 2 is a schematic diagram of some components of the example refrigerator device of FIG. 1 .

[0012] FIG. 3 is a cross-sectional view of a linear compressor according to an exemplary embodiment of the present application.

[0013] FIG. 4 is a cross-sectional view of the coupling of the linear compressor shown in FIG. 3 .

[0014] FIG5 is an exploded cross-sectional view of the coupling of FIG4.

[0015] Repeated use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present application. DETAILED DESCRIPTION

[0016] Embodiments of the present application will now be described in detail, one or more examples of which are illustrated in the accompanying drawings. Each example is intended to explain the present application, not to limit the present application. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present application without departing from the scope of the present application. For example, features shown or described as part of one embodiment may be used in conjunction with another embodiment to produce a further embodiment. Therefore, the present application is intended to cover modifications and variations within the scope of the appended claims and their equivalents.

[0017] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Furthermore, references to "an embodiment" or "one embodiment" do not necessarily refer to the same embodiment, although they may. Any implementation described herein as "exemplary" or "embodiment" is not necessarily to be construed as preferred or advantageous over other implementations.

[0018] As used herein, the terms "first," "second," and "third" are used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of the various components. The terms "includes" and "including," like the term "comprising," are intended to be inclusive. Similarly, the term "or" is generally intended to be inclusive (e.g., "A or B" means "A or B or both"). In addition, here and throughout the specification and claims, range limitations may be combined or interchanged. Unless the context or language indicates otherwise, these ranges are indicated and include all subranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable. The singular includes the plural unless the context clearly dictates otherwise.

[0019] Approximate language used herein in the specification and claims may be used to modify any quantitative expression that is permitted to vary without changing the basic function to which it is related. Therefore, values ​​modified by one or more terms such as "substantially," "approximately," and "substantially" are not limited to the precise values ​​specified. At least in some cases, approximate language may correspond to the accuracy of an instrument used to measure the value, or the accuracy of a method or machine used to construct or manufacture a component or system. For example, approximate language may refer to being within 10% (i.e., including values ​​within 10% greater or less than the stated value). In this regard, for example, when used in the context of an angle or direction, these terms include values ​​within 10 degrees greater or less than the stated angle or direction (e.g., "substantially perpendicular" includes forming an angle of no more than 10 degrees with the vertical direction V in any direction, such as clockwise or counterclockwise).

[0020] Unless explicitly stated otherwise, references to a single processing element (e.g., a "controller," "processor," "microprocessor," etc.) are understood to include more than one processing element. In other words, "processing element" is generally understood to mean "one or more processing elements." Furthermore, unless specifically stated to the contrary, any step or function performed by "a processing element" or "the processing element" is generally understood to be capable of being performed by "any of the one or more processing elements." Thus, a first step or function performed by "a processing element" may be performed by "any of the one or more processing elements," while a second step or function performed by "the processing element" may be performed by "any of the one or more processing elements," and not necessarily by the same processing element that performed the first step or function. Furthermore, it should be understood that a reference to "a processing element" or "the processing element" performing multiple steps or functions does not require that at least one discrete processing element be capable of performing each of the multiple steps or functions.

[0021] The reference to any prior art in the specification is not and should not be taken as an admission or any form of suggestion that the prior art forms part of the common general knowledge in the application area or any other jurisdiction, or that the prior art could reasonably be understood and regarded as relevant by a person skilled in the art.

[0022] It should be noted that exemplary embodiments of the present application may provide an apparatus, refrigeration assembly, or linear compressor that advantageously reduces or prevents friction within the linear compressor, for example by reducing or preventing cross loading on the piston that may occur due to axial misalignment of the piston.

[0023] Turning now to the figures, FIG1 depicts a refrigerator unit 10 comprising a closed refrigeration system 60 ( FIG2 ). It should be understood that the term "refrigeration unit" herein refers generally to any type of refrigeration unit, such as a freezer, a refrigerator / freezer combination, and any style or model of conventional refrigerator. Furthermore, it should be understood that the present application is not limited to use in refrigerator units. Thus, the present application may be used for any other suitable application, such as vapor compression in air conditioning equipment or air compression in an air compressor.

[0024] In the exemplary embodiment shown in FIG1 , a refrigerator unit 10 is depicted as an upright refrigerator having a cabinet or housing 12 defining a plurality of internal chilled storage compartments. Specifically, the refrigerator unit 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 that can be manually moved into and out of the freezer compartment 18 via a suitable sliding mechanism.

[0025] FIG2 is a schematic diagram of certain components of the refrigerator unit 10, including the closed refrigeration system 60 of the refrigerator unit 10. A mechanical compartment 62 contains components for performing a known vapor compression cycle to cool air. These components include a compressor 64, a condenser 66, an expansion device 68, and an evaporator 70, all connected in series and filled with refrigerant. Those skilled in the art will appreciate that the refrigeration system 60 may include other components (e.g., at least one additional evaporator, compressor, expansion device, or condenser). For example, the refrigeration system 60 may include two evaporators.

[0026] In the refrigeration system 60, the refrigerant flows into the compressor 64, which operates to increase the pressure of the refrigerant. The temperature of the refrigerant increases after compression, and the temperature of the refrigerant decreases after passing through the condenser 66. In the condenser 66, the refrigerant exchanges heat with the ambient air, thereby cooling the refrigerant. As shown by arrow A C As shown, fan 72 is used to pull air through condenser 66, thereby providing forced convection, which allows for more rapid and efficient heat exchange between the refrigerant within condenser 66 and the ambient air. Therefore, as will be appreciated by those skilled in the art, increasing the air flow through condenser 66 (e.g., by improving cooling of the refrigerant contained in condenser 66) can improve the efficiency of condenser 66.

[0027] An expansion device 68 (such as a valve, capillary tube, or other restrictive device) receives refrigerant from the condenser 66. From the expansion device 68, the refrigerant enters the evaporator 70. After exiting the expansion device 68 and entering the evaporator 70, the refrigerant's pressure decreases. Due to this pressure drop, or phase change, the evaporator 70 becomes cooler than the fresh food compartment 14 and freezer compartment 18 of the refrigerator unit 10. Consequently, cooled air is generated, cooling the fresh food compartment 14 and freezer compartment 18 of the refrigerator unit 10. Therefore, the evaporator 70 acts as a heat exchanger, transferring heat from the air passing through the evaporator 70 to the refrigerant flowing through the evaporator 70.

[0028] The vapor compression cycle components, associated fans, and associated chambers in the refrigeration circuit, sometimes collectively referred to as a closed refrigeration system, are operable to force cool air through the fresh food compartment 14 and the freezer compartment 18 ( FIG. 1 ). The refrigeration system 60 depicted in FIG. 2 is provided as an example only. Therefore, other refrigeration system configurations may also be used within the scope of the present application.

[0029] FIG3 is a cross-sectional view of a linear compressor 100 according to an exemplary embodiment of the present application. As discussed in more detail below, the linear compressor 100 is operable to increase the pressure of a fluid within a cavity 118 of the linear compressor 100 . The linear compressor 100 can be used to compress any suitable fluid, such as a refrigerant or air. In particular, the linear compressor 100 can be used in a refrigeration appliance, such as the refrigeration appliance 10 ( FIG1 ), where the linear compressor 100 can serve as the compressor 64 ( FIG2 ). As shown in FIG3 , the linear compressor 100 defines an axial direction A, a radial direction R, and a circumferential direction C. The linear compressor 100 can be enclosed in a sealed or airtight housing (not shown). The sealed housing can, for example, inhibit or prevent refrigerant from leaking or escaping from the refrigeration system 60.

[0030] Turning now to FIG. 3 , linear compressor 100 includes a housing 110 extending between a first end 112 and a second end 114 (e.g., along an axial direction A). Housing 110 includes various static or non-moving structural components of linear compressor 100. Specifically, housing 110 includes a cylinder 116 defining a cavity 118. Cylinder 116 is located at or adjacent to first end 112 of housing 110. Cavity 118 extends longitudinally along axial direction A. A stator of a motor (e.g., including an outer back iron 120 and a drive coil 122) is mounted or secured to housing 110. In some embodiments, linear compressor 100 further includes a valve (e.g., a discharge valve 119 located at an end of cavity 118) that allows refrigerant to enter and exit cavity 118 during operation of linear compressor 100.

[0031] A piston 130 with a piston head 132 is slidably received within the cavity 118 of the cylinder 116 . Specifically, the piston 130 is capable of sliding along an axial direction A. While sliding within the cavity 118 , the piston head 132 compresses the refrigerant within the cavity 118 . For example, the piston head 132 may slide within the cavity 118 from a top dead center position to a bottom dead center position along the axial direction A (i.e., an expansion stroke of the piston head 132 ). When the piston head 132 reaches the bottom dead center position, the piston head 132 changes direction and slides back within the cavity 118 to a top dead center position (i.e., a compression stroke of the piston head 132 ). It should be understood that the linear compressor 100 may include an additional piston head or an additional cavity at the other end of the linear compressor 100 . Therefore, in other exemplary embodiments, the linear compressor 100 may include multiple piston heads.

[0032] As shown in FIG3 , the linear compressor 100 further includes a shifter, such as an inner back iron 140 . The inner back iron 140 is located within the motor stator. Specifically, the outer back iron 120 or the drive coil 122 may extend around the inner back iron 140 (e.g., along a circumferential direction C). The inner back iron 140 also has an outer surface facing the outer back iron 120 or the drive coil 122 . At least one drive magnet 142 is mounted on the inner back iron 140 (e.g., mounted on an outer surface of the inner back iron 140 ). The drive magnet 142 may face or be exposed to the drive coil 122 . Specifically, the drive magnet 142 may be spaced apart from the drive coil 122 (e.g., separated by an air gap in a radial direction R). Thus, the air gap may be defined between the opposing surfaces of the drive magnet 142 and the drive coil 122 . The drive magnet 142 may also be mounted or fixed to the inner back iron 140 such that the outer surface of the drive magnet 142 is substantially flush with the outer surface of the inner back iron 140 . Therefore, the driving magnet 142 can be embedded in the inner back iron 140. In this way, during operation of the linear compressor 100, the magnetic field of the driving coil 122 may only need to pass through a single air gap between the outer back iron 120 and the inner back iron 140, which can improve the efficiency of the linear compressor 100 compared to a linear compressor with air gaps on both sides of the driving magnet.

[0033] As shown in FIG3 , the drive coil 122 extends around the inner back iron 140 (e.g., along a circumferential direction C). In other exemplary embodiments, the inner back iron 140 may extend around the drive coil 122 along the circumferential direction C. The drive coil 122 is operable to move the inner back iron 140 in an axial direction A during operation of the drive coil 122. For example, a current may be induced in the drive coil 122 by a current source (not shown) to generate a magnetic field. This magnetic field acts on the drive magnet 142 and causes the piston 130 to move in the axial direction A, thereby compressing the refrigerant within the chamber 118, as described above and understood by those skilled in the art. Specifically, the magnetic field of the drive coil 122 may act on the drive magnet 142 to move the inner back iron 140 and the piston head 132 in the axial direction A during operation of the drive coil 122. Therefore, during operation of the drive coil 122, the drive coil 122 may cause the piston 130 to slide between a top dead center position and a bottom dead center position (e.g., by moving the inner back iron 140 in the axial direction A).

[0034] The linear compressor 100 may include various components for enabling or regulating the operation of the linear compressor 100. Specifically, the linear compressor 100 includes a controller (not shown) configured to regulate the operation of the linear compressor 100. The controller is in (e.g., operative) communication with the motor (e.g., the drive coil 122 of the motor). Thus, the controller can selectively activate the drive coil 122 (e.g., by inducing a current in the drive coil 122) to compress the refrigerant using the piston 130 as described above.

[0035] The controller includes memory and one or more processing devices, such as a microprocessor, central processing unit (CPU), or similar device, such as a general-purpose or special-purpose microprocessor, operable to execute programmed instructions or microcontrol code related to the operation of the linear compressor 100. The memory can be random access memory (such as DRAM) or read-only memory (such as ROM or FLASH). The processor executes the programmed instructions stored in the memory. The memory can be a separate component from the processor or internal to the processor. Alternatively, the controller can be constructed without using a microprocessor (for example, using a combination of discrete analog or digital logic circuits, such as switches, amplifiers, integrators, comparators, flip-flops, and AND gates, to perform control functions, rather than relying on software).

[0036] The linear compressor 100 also includes a pair of planar springs 150. Each planar spring 150 can be coupled to a respective end of the inner back iron 140 (e.g., along the axial direction A). The planar springs 150 support the inner back iron 140 during operation of the drive coil 122. Specifically, the inner back iron 140 is suspended within the motor stator of the linear compressor 100 by the planar springs 150, such that movement of the inner back iron 140 in the radial direction R is hindered or restricted, while movement in the axial direction A is relatively unimpeded. Therefore, the stiffness of the planar springs 150 in the radial direction R can be significantly greater than the stiffness in the axial direction A. In this way, the planar springs 150 can help maintain a uniform air gap between the drive magnet 142 and the drive coil 122 (e.g., along the radial direction R) during motor operation and movement of the inner back iron 140 in the axial direction A. The planar springs 150 can also help prevent lateral pulling forces of the motor from being transmitted to the piston 130 and reacting as frictional losses in the cylinder 116.

[0037] The inner back iron 140 includes an outer cylinder 144 and an inner sleeve 146. The outer cylinder 144 defines the outer surface of the inner back iron 140 and also has an inner surface 143 opposite the outer surface of the outer cylinder 144. The inner sleeve 146 is located on or at the inner surface 143 of the outer cylinder 144. A first interference fit between the outer cylinder 144 and the inner sleeve 146 can combine or secure the outer cylinder 144 and the inner sleeve 146 together. In alternative exemplary embodiments, the inner sleeve 146 can be welded, bonded, fastened, or connected to the outer cylinder 144 using any other suitable mechanism or method.

[0038] The outer cylinder 144 can be made of or constructed using any suitable material. For example, the outer cylinder 144 can be constructed from or include a plurality of (e.g., ferromagnetic) laminations. The laminations are arranged along a circumferential direction C to form the outer cylinder 144 and are mounted or secured to one another (e.g., by pressing a ring onto the ends of the laminations). The outer cylinder 144 defines a groove that extends inward from an outer surface of the outer cylinder 144 (e.g., along a radial direction R). The drive magnet 142 is positioned within the groove in the outer cylinder 144 (e.g., such that the drive magnet 142 is embedded within the outer cylinder 144).

[0039] The flexible mounting member 210 is mounted on the inner back iron 140 and extends through the inner back iron 140. Specifically, the flexible mounting member 210 is mounted on the inner back iron 140 via the inner sleeve 146. Thus, the flexible mounting member 210 can be connected (e.g., threadedly connected) to the inner sleeve 146 or an intermediate portion of the flexible mounting member 210 to mount or secure the flexible mounting member 210 to the inner sleeve 146. The flexible mounting member 210 can help form the coupling 200. The coupling 200 connects the inner back iron 140 and the piston 130, thereby transmitting movement of the inner back iron 140 (e.g., in the axial direction A) to the piston 130.

[0040] The coupling 200 may be a compliant coupling having compliance or flexibility in the radial direction R. Specifically, the coupling 200 may have sufficient compliance in the radial direction R such that little or no movement of the inner back iron 140 in the radial direction R is transmitted through the coupling 200 to the piston 130. In this manner, the lateral pulling force of the motor is decoupled from the piston 130 or the cylinder 116, and friction between the piston 130 and the cylinder 116 may be reduced.

[0041] FIG4 is a (for example, partial) cross-sectional view of coupling 200, and FIG5 is an exploded cross-sectional view of coupling 200. As can be seen in FIG4 and FIG5 , piston 130 includes a piston head 132 and a cylindrical sidewall 134. Cylindrical sidewall 134 may extend in an axial direction A from piston head 132 toward inner back iron 140. An outer surface 136 of cylindrical sidewall 134 may slide on cylinder 116 within cavity 118. An inner surface 138 of cylindrical sidewall 134 opposes outer surface 136 of cylindrical sidewall 134. Thus, outer surface 136 of cylindrical sidewall 134 may face away from the center of cylindrical sidewall 134 in radial direction R, while inner surface 138 of cylindrical sidewall 134 may face toward the center of cylindrical sidewall 134 in radial direction R. Inner surface 138 of cylindrical sidewall 134 defines a ball seat 139.

[0042] The flexible mount 210 extends (e.g., in an axial direction A) between a first end 212 and a second end 214. The flexible mount 210 is coupled to the inner back iron 140 at a location distal from the first end 212 of the flexible mount 210. For example, the flexible mount 210 can be coupled to the inner back iron 140 at the second end 214 of the flexible mount 210 or between the first end 212 and the second end 214 of the flexible mount 210. Conversely, the flexible mount 210 is positioned at or within the piston 130 at the first end 212 of the flexible mount 210, as will be discussed in detail below.

[0043] The flexible mount 210 includes a tubular wall 216 between the inner back iron 140 and the piston 130. A passage 218 within the tubular wall 216 is configured to direct a compressible fluid (e.g., refrigerant or air) through the flexible mount 210 toward the piston head 132 or into the piston 130. The inner back iron 140 can be mounted to the flexible mount 210 such that the inner back iron 140 extends around the tubular wall 216 (e.g., at a mid-portion of the flexible mount 210 between the first end 212 and the second end 214 of the flexible mount 210). The passage 218 can extend within the tubular wall 216 between the first end 212 and the second end 214 of the flexible mount 210, thereby allowing the compressible fluid to flow from the first end 212 to the second end 214 of the flexible mount 210 through the passage 218. Thus, during operation of the linear compressor 100, the compressible fluid can flow through the inner back iron 140 within the flexible mount 210. The muffler 160 may be located in the passage 218 within the tubular wall 216. The muffler 160 reduces the noise of the compressible fluid flowing through the passage 218.

[0044] The piston head 132 also defines at least one opening 133. The opening 133 of the piston head 132 extends (e.g., in the axial direction A) through the piston head 132. Thus, during operation of the linear compressor 100, fluid flow can pass through the piston head 132 through the opening 133 of the piston head 132 and into the cavity 118. Thus, during operation of the linear compressor 100, the fluid flow (compressed by the piston head 132 within the cavity 118) can flow within the passage 218, through the flexible mount 210 and the inner back iron 140, toward the piston 130. In some embodiments, a valve on the piston head 132 regulates the flow of compressible fluid into the cavity 118 through the opening 133.

[0045] The coupling 200 also includes a ball head 220. The ball head 220 is located at the first end 212 of the flexible mount 210 and can contact the flexible mount 210 at the first end 212 of the flexible mount 210. Furthermore, the ball head 220 can contact the piston 130 at the ball seat 139 of the piston 130. Specifically, the ball head 220 can be seated on the ball seat 139 of the piston 130 such that the ball head 220 can slide or rotate on the ball seat 139 of the piston 130. For example, the ball head 220 can have a frusto-spherical surface 222 that abuts the ball seat 139 of the piston 130. The ball seat 139 can have a shape that complements the frusto-spherical surface 222 of the ball head 220. The frusto-spherical surface 222 of the ball head 220 can slide or rotate on the ball seat 139 of the piston 130.

[0046] The relative motion between the flexible mount 210 and the piston 130 at the interface between the ball head 220 and the ball seat 139 of the piston 130 can reduce friction between the piston 130 and the cylinder 116 (e.g., compared to a fixed connection between the flexible mount 210 and the piston 130). For example, when the axis about which the piston 130 slides within the cylinder 116 is tilted relative to the axis about which the inner back iron 140 reciprocates, the spherical cut surface 222 of the ball head 220 can slide on the ball seat 139 of the piston 130, thereby reducing friction between the piston 130 and the cylinder 116 relative to a rigid connection between the inner back iron 140 and the piston 130.

[0047] As shown in FIG5 , the first end 212 of the flexible mounting member 210 includes or defines an axial flange or edge. In some embodiments, the axial flange or edge of the flexible mounting member 210 is defined as a frusto-conical edge 211 . As shown, the frusto-conical edge 211 may extend about the axial direction A. Furthermore, the frusto-conical edge may define a set angle θ (e.g., relative to the radial direction R). Optionally, the set angle θ may be between 10° and 30°, for example, approximately 20°. During assembly, the ball stud 220 may contact the axial flange or edge (e.g., the frusto-conical edge 211 ) of the flexible mounting member 210 . For example, the ball stud 220 may include or define its own axial flange or edge that points toward (e.g., contacts) the first end 212 . In some embodiments, the axial flange or edge of the ball stud 220 is defined as a complementary edge or annular edge 221 . The complementary edge 221 of the ball stud 220 may be concentric with the frusto-conical edge 211 of the flexible mounting member 210 . For example, the frustoconical edge 211 can be positioned concentrically with the complementary edge 221. In some such embodiments, the frustoconical edge 211 is located within the complementary edge 221 (e.g., along the radial direction R). Optionally, the complementary edge 221 is defined to be at a predetermined angle that matches or is opposite to the set edge. Notably, the engagement between the frustoconical edge 211 and the complementary edge 221 can serve to align or axially align the ball head 220 during use.

[0048] In some embodiments, the coupling 200 is equipped with a freeze ring 226. Specifically, the freeze ring 226 can be located at the first end 212 of the flexible mount 210. The freeze ring 226 itself can include multiple discrete segments, such as a shoulder segment 250 or a guide wall segment 252. Optionally, the freeze ring 226 can be mounted to or fixed relative to the flexible mount 210. For example, the flexible mount 210 can include an inner seat 228. The inner seat 228 can extend radially inward (e.g., in the axial direction A) between the first end 212 and the second end 214. Furthermore, the inner seat 228 can extend annularly, such as by providing an inner ring or by providing a plurality of annularly spaced tabs to provide clearance between the inner rings. The freeze ring 226 can be supported (e.g., axially) on the inner seat 228. As shown, the shoulder segment 250 can be radially retained within the flexible mount 210, with the rear portion or trailing edge of the freeze ring 226 positioned to abut against the inner seat 228. In some such embodiments, the shoulder segment 250 defines a shoulder outer diameter DS (eg, in a radial direction or perpendicular to the axial direction A), while the guide wall segment 252 defines a wall outer diameter DW. As shown, the shoulder outer diameter DS can be greater than the wall outer diameter DW.

[0049] During assembly, at least a portion of the retaining ring 226 (e.g., the guide wall segment 252) can be disposed radially inward from the ball head 220. Thus, along a common position relative to the axial direction A, a portion of the retaining ring 226 can be disposed radially inward from the ball head 220 (e.g., concentric with the ball head 220). Alternatively, a distal end of the retaining ring 226 can be enclosed or wrapped around the ball head 220 (e.g., such that the retaining ring 226 does not extend outside the ball head 220 in a direction opposite from the flexible mount 210). Furthermore, the inner surface 254 of the ball head 220 can face or be oriented toward the guide wall segment 252 of the retaining ring 226. Furthermore, the ball head inner diameter DI can be defined by the inner surface 254 (e.g., a minimum diameter) and be greater than the wall outer diameter DW defined by the guide wall segment 252. As shown, a radial gap G can be defined between the guide wall segment 252 and the inner surface 254. Specifically, radial clearance G can be defined as a gap between 0.1 mm and 0.3 mm, for example, approximately 0.2 mm. In addition to radial clearance G, the inner diameter DI of ball head 220 can be smaller than the outer diameter DS of the shoulder. Ball head 220 can bear against or otherwise axially constrain shoulder segment 250. Furthermore, ball head 220 can further serve to axially limit movement of retaining ring 226 (e.g., at shoulder segment 250, such as by sandwiching shoulder segment 250 between inner seat 228 and at least a portion of ball head 220).

[0050] During use, the retaining ring 226 can guide the variable axial alignment of the ball head 220. For example, the radial gap G allows the ball head 220 to move relative to the retaining ring 226 (e.g., in a radial direction R), thereby allowing the ball head 220 to move relative to the flexible mount 210. The movement of the ball head 220 relative to the flexible mount 210 (e.g., in the radial direction R) can help reduce friction between the piston 130 and the cylinder 116 compared to a rigid connection between the inner back iron 140 and the piston 130. For example, when the axis along which the piston 130 slides within the cylinder 116 is offset in the radial direction R relative to the axis along which the inner back iron 140 reciprocates, the radial gap G allows the ball head 220 to move relative to the flexible mount 210 in the radial direction R, thereby reducing friction between the piston 130 and the cylinder 116 compared to a rigid connection between the inner back iron 140 and the piston 130.

[0051] The coupling 200 also includes features for mounting the ball head 220 to the flexible mount 210. Specifically, the coupling 200 includes a post 230 extending from the piston 130 into the flexible mount 210 at the first end 212 of the flexible mount 210 (e.g., through the retaining ring 226). A spring 232 is engaged with the post 230 and the flexible mount 210 (e.g., rearwardly from the retaining ring relative to the axial direction A). During assembly, the spring 232 urges the ball head 220 against the ball seat 139 of the piston 130. Specifically, the spring 232 can compress the ball head 220 between the flexible mount 210 and the ball seat 139 of the piston 130 in the axial direction A (e.g., by pulling the piston 130 toward the ball head 220 and the flexible mount 210). The spring 232 may be preloaded to hold the coupling 200 together (and prevent knocking during oscillation of the piston 130 ) while also allowing enough radial flexibility to allow the interface between the ball head 220 and the ball seat 139 of the piston 130 to move with low friction.

[0052] A preload ring 234 can be positioned within the flexible mount 210 at the first end 212 of the flexible mount 210. A head 231 of the post 230 can be positioned opposite the piston head 132 of the piston 130 with respect to the preload ring 234. The post 230 can be threadedly coupled to the piston head 132 of the piston 130 and can extend through the preload ring 234 in the axial direction A. Specifically, the post 230 can extend from the piston head 132 of the piston 130 in the axial direction A through the preload ring 234. The spring 232 can be compressed between the head 231 of the post 230 and the preload ring 234 (e.g., such that the spring 232 urges the ball head 220 against the ball seat 139 of the piston 130).

[0053] As described above, the tubular wall 216 of the flexible mount 210 extends between the inner back iron 140 and the piston 130 (e.g., along the axial direction A). The cylindrical sidewall 134 of the piston 130 extends around the tubular wall 216 at the first end 212 of the flexible mount 210. An annular gap AG is defined between the cylindrical sidewall 134 of the piston 130 and the tubular wall 216 of the flexible mount 210. Lubricating oil can flow through the annular gap AG to the interface between the ball head 220 and the ball seat 139 of the piston 130. This lubricating oil lubricates the interface between the ball head 220 and the ball seat 139 of the piston 130, reducing friction between the ball head 220 and the ball seat 139 of the piston 130. However, the interface between the ball head 220 and the ball seat 139 of the piston 130 can also prevent a significant amount of oil from flowing into the passage 218 and, therefore, into the cavity 118.

[0054] Both the flexible mounting member 210 and the ball head 220 can be made of or constructed using a suitable plastic, such as a thermoplastic. In some exemplary embodiments, the flexible mounting member 210 or the ball head 220 can be made of or constructed using polybutylene terephthalate. The ball head 220 can also be impregnated with fiberglass to help it withstand dynamic loads. As another example, the ball head 220 can be made of Teflon® or molybdenum to reduce friction between the ball head 220 and the ball seat 139 of the piston 130.

[0055] Compared to known couplings, coupling 200 can be manufactured in high volumes at low cost. For example, ball seat 139 can be CNC-machined into piston 130 with sufficient finish and precision to avoid the need for further finishing, as with known ball joints that require grinding and polishing. Ball head 220 can also be injection molded with sufficient finish and precision. Alternatively, ball head 220 can be CNC-machined from cast iron. Furthermore, coupling 200 can use a single ball joint to connect inner back iron 140 to piston 130, compared to known couplings that use two ball joints. Additionally or alternatively, the disclosed embodiments can also improve performance consistency (e.g., by increasing compressor performance by 3% to 5% compared to existing linear compressor assemblies). Additionally or alternatively, the disclosed embodiments (e.g., including retaining ring 226) can ensure secure assembly of linear compressor 100 (e.g., by preventing misalignment between piston 130 and ball seat 139).

[0056] This written description uses examples to disclose the present application, including the best mode, and also to enable any person skilled in the art to practice the present application, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the present application is defined by the claims and may include other examples that occur to those skilled in the art. If such other examples include structural elements that do not differ from the literal language of the claims, or include equivalent structural elements that do not differ substantially from the literal language of the claims, then such other examples are intended to fall within the scope of the claims.

Claims

1. A linear compressor comprising: Drive coil; a mover adjacent to the drive coil, the drive coil being operable to reciprocate the mover relative to the drive coil; a piston having a piston head and a cylindrical sidewall, an inner surface of the cylindrical sidewall defining a ball seat; as well as a coupling extending between the mover and the piston, the coupling comprising: a flexible mounting member extending between a first end and a second end, the flexible mounting member being coupled to the mover at a location distal from the first end of the flexible mounting member, a ball head located at the first end of the flexible mount, the ball head contacting the piston at the ball seat of the piston, and A retaining ring is positioned radially inward from the ball head at the first end of the flexible mount for guiding variable axial alignment of the coupling.

2. The linear compressor according to claim 1, wherein The flexible mount defines a frusto-conical edge at the first end that contacts a trailing edge of the ball head.

3. The linear compressor according to claim 2, wherein: The frustoconical edge defines a setting angle relative to the radial direction, the setting angle being between 10° and 30°.

4. The linear compressor according to claim 1, wherein: A radial gap is defined between the guide wall section of the positioning ring and the inner surface of the ball head.

5. The linear compressor according to claim 1, wherein The flexible mount includes an inner seat extending radially inwardly between the first end and the second end, and wherein the retaining ring is supported on the inner seat within the flexible mount.

6. The linear compressor according to claim 1, wherein The positioning ring includes a shoulder section defining a shoulder outer diameter and a guide wall section defining a wall outer diameter, the shoulder outer diameter being larger than the wall outer diameter, and The inner diameter of the ball head is smaller than the outer diameter of the shoulder portion, so as to axially limit the movement of the positioning ring in the shoulder segment.

7. The linear compressor according to claim 1, wherein: The coupling further includes a post extending from the piston through the retaining ring and into the flexible mount.

8. The linear compressor according to claim 7, wherein: The coupling further includes a spring coupled from the retaining ring back to the post and the flexible mount such that the spring urges the ball head against the ball seat of the piston.

9. The linear compressor according to claim 1, wherein: The flexible mount includes a tubular wall between the mover and the piston, a passage within the tubular wall configured to direct refrigerant through the flexible mount toward the piston head of the piston.

10. The linear compressor according to claim 9, wherein The mover is mounted to the flexible mount such that the mover extends around the tubular wall.

11. A linear compressor comprising: Drive coil; a mover adjacent to the drive coil, the drive coil being operable to reciprocate the mover relative to the drive coil; a piston having a piston head and a cylindrical sidewall, an inner surface of the cylindrical sidewall defining a ball seat; as well as a coupling extending between the mover and the piston, the coupling comprising: a flexible mounting member extending between a first end and a second end, the flexible mounting member being coupled to the mover at a location distal to the first end of the flexible mounting member, the flexible mounting member defining a frusto-conical edge at the first end, and A ball head is located at the first end of the flexible mounting member, the ball head contacts the truncated cone edge, and the ball head further contacts the piston at the ball seat of the piston.

12. The linear compressor according to claim 11, wherein The frustoconical edge defines a setting angle relative to the radial direction, the setting angle being between 10° and 30°.

13. The linear compressor according to claim 11, wherein The coupling further includes a locating ring positioned radially inward from the ball head at the first end of the flexible mount for guiding the variable axial alignment of the coupling, the locating ring defining a radial gap between a guide wall segment of the locating ring and an inner surface of the ball head.

14. The linear compressor according to claim 13, wherein: The flexible mount includes an inner seat extending radially inwardly between the first end and the second end, and wherein the retaining ring is supported on the inner seat within the flexible mount.

15. The linear compressor of claim 13, wherein: The positioning ring includes a shoulder section defining a shoulder outer diameter and the guide wall section defining a wall outer diameter, the shoulder outer diameter being larger than the wall outer diameter, and The inner diameter of the ball head is smaller than the outer diameter of the shoulder portion, so as to axially limit the movement of the positioning ring in the shoulder segment.

16. The linear compressor of claim 13, wherein: The coupling further includes a post extending from the piston through the retaining ring and into the flexible mount.

17. The linear compressor of claim 16, wherein: The coupling further includes a spring coupled from the retaining ring back to the post and the flexible mount such that the spring urges the ball head against the ball seat of the piston.

18. The linear compressor of claim 11, wherein The flexible mount includes a tubular wall between the mover and the piston, a passage within the tubular wall configured to direct refrigerant through the flexible mount toward the piston head of the piston.

19. The linear compressor of claim 18, wherein: The mover is mounted to the flexible mount such that the mover extends around the tubular wall.

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