Abstract:
A compressor may include a shell, a crankshaft, a piston and a connecting rod. The shell may define a cylinder. The crankshaft is supported for rotation relative to the shell. The piston reciprocates within the cylinder in response to rotation of the crankshaft. The piston and the cylinder define a compression chamber therebetween. The connecting rod includes a first bushing rotatably coupled to the piston and a second bushing rotatably coupled to the crankshaft. The second bushing may include a driving surface contacting the crankshaft and having a recess formed therein. The recess receives an insert.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/066,008, filed on Oct. 20, 2014. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a compressor, and more particularly, to a crankshaft-connecting rod assembly of a compressor. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure and is not necessarily prior art. 
         [0004]    Reciprocating compressors typically include a motor and one or more piston-cylinder arrangements. Operation of the motor drives a crankshaft, which imparts a force on each piston via connecting rods to move the pistons within and relative to respective cylinders. In so doing, a pressure of working fluid disposed within the cylinders is increased. 
         [0005]    Reciprocating compressors may be used in climate control systems such as heating, ventilation, air conditioning and refrigeration systems (HVACR) to circulate a refrigerant amongst the various components of the climate control system. For example, a reciprocating compressor may receive low-pressure, gaseous refrigerant from an evaporator and compress the refrigerant to a higher pressure. The compressed refrigerant may exit the compressor and flow through a condenser to allow some or all of the refrigerant to change phase from a gas to a liquid. Thereafter, the refrigerant may be expanded via an expansion valve prior to returning to the evaporator where the cycle begins anew. 
         [0006]    After being manufactured, compressors often sit idle (e.g., in a manufacturer&#39;s inventory or in an installation contractor&#39;s inventory) for a relatively long period of time (often several months or more) prior to being installed into and/or operated in a climate control system. Furthermore, compressors sometimes sit idle for long periods of time between periods of operation (i.e., when the climate control system is shut off for a prolonged period of time). As a result, lubricants applied to various moving components of the compressor during assembly of the compressor can, over time, drip off of various components and settle in the bottom of the compressor. Furthermore, during such prolonged idle periods, refrigerant from throughout the climate control system can migrate into the bottom of the compressor, which can hinder lubricant flow through the crankshaft at initial startup of the compressor. Therefore, a compressor that has been sitting idly for a relatively long period of time before initial installation and/or initial operation or a compressor that has been sitting idly (i.e., shutoff) for a relatively long period of time between periods of operation can have moving components that are under-lubricated (i.e., having no lubricant or not enough lubricant) at the initial startup of the compressor, which can cause damage to the compressor. For example, interfaces between the connecting rods and the crankshaft of the compressor can be particularly susceptible to such under-lubrication, which can lead to a seizure of the connecting rods and crankshaft. Such a seizure can catastrophically damage the compressor. 
       SUMMARY 
       [0007]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0008]    A compressor may include a shell, a crankshaft, a piston and a connecting rod. The shell may define a cylinder. The crankshaft is supported for rotation relative to the shell. The piston reciprocates within the cylinder in response to rotation of the crankshaft. The piston and the cylinder define a compression chamber therebetween. The connecting rod includes a first bushing rotatably coupled to the piston and a second bushing rotatably coupled to the crankshaft. The second bushing may include an arched driving surface contacting the crankshaft and having a recess formed therein. The recess may receive an insert. 
         [0009]    In some configurations, the insert is formed from a different material than the driving surface. The insert may contact the crankshaft or a piston pin. 
         [0010]    In some configurations, the insert is formed from a material having a higher lubricity than a material of the driving surface. 
         [0011]    In some configurations, the insert is formed from a polymeric material. 
         [0012]    In some configurations, the insert is formed from an unleaded bearing alloy. 
         [0013]    In some configurations, the driving surface is formed from aluminum. 
         [0014]    In some configurations, the insert includes a first lubricant bore in fluid communication with a second lubricant bore extending through the second bushing. 
         [0015]    In some configurations, at least a portion of the insert is aligned with a longitudinal axis of the connecting rod. 
         [0016]    In some configurations, opposing edges of the insert are angularly spaced apart from the longitudinal axis such that the longitudinal axis extends through a central portion of the insert. 
         [0017]    In some configurations, another portion of the insert is angularly spaced apart from the longitudinal axis by thirty degrees. 
         [0018]    In some configurations, another portion of the insert is angularly spaced apart from the longitudinal axis by sixty degrees. 
         [0019]    In some configurations, another portion of the insert is angularly spaced apart from the longitudinal axis by an angle between thirty and sixty degrees. 
         [0020]    In some configurations, a surface of the insert is flush with the driving surface. 
         [0021]    In some configurations, the insert extends through first and second opposing axial ends of the second bushing. 
         [0022]    In some configurations, the insert engages the recess by a press fit. 
         [0023]    In some configurations, the connecting rod can be cast around the insert. 
         [0024]    In another form, the present disclosure provides a reciprocating compressor that includes a crankshaft, a piston reciprocating within a cylinder in response to rotation of the crankshaft, and a connecting rod. The piston and the cylinder define a compression chamber therebetween. The connecting rod includes a first bushing coupled to the piston and a second bushing coupled to the crankshaft. Each of the first and second bushings includes a driving surface that is formed of a first material. The first bushing may contact a piston pin. The second bushing may contact the crankshaft. The driving surface of one of the first and second bushings may have a recess formed therein in which an insert is received. The insert may be formed from a second material (e.g., a high-lubricity material). 
         [0025]    In some configurations, the insert is formed from a polymeric material. 
         [0026]    In some configurations, the insert is formed from an unleaded bearing alloy. 
         [0027]    In some configurations, the driving surface is formed from aluminum. 
         [0028]    In some configurations, the insert includes a first lubricant bore in fluid communication with a second lubricant bore extending through the second bushing. 
         [0029]    In some configurations, at least a portion of the insert is aligned with a longitudinal axis of the connecting rod. 
         [0030]    In some configurations, opposing edges of the insert are angularly spaced apart from the longitudinal axis such that the longitudinal axis extends through a central portion of the insert. 
         [0031]    In some configurations, another portion of the insert is angularly spaced apart from the longitudinal axis by thirty degrees. 
         [0032]    In some configurations, another portion of the insert is angularly spaced apart from the longitudinal axis by sixty degrees. 
         [0033]    In some configurations, another portion of the insert is angularly spaced apart from the longitudinal axis by an angle between thirty and sixty degrees. 
         [0034]    In some configurations, a surface of the insert is flush with the driving surface. 
         [0035]    In some configurations, the insert extends through first and second opposing axial ends of the second bushing. 
         [0036]    In some configurations, the insert engages the recess by a press fit. 
         [0037]    In some configurations, the connecting rod can be cast around the insert. 
         [0038]    In another form, the present disclosure provides a compressor that may include an insert received in a recess in a surface contacting a crankshaft connected to a piston by a connecting rod. The piston reciprocates within a cylinder upon rotation of the crankshaft. The piston and cylinder define a compression chamber. 
         [0039]    In some configurations, the surface is a driving surface of a bushing of the connecting rod. 
         [0040]    In some configurations, the insert is flush with the driving surface. 
         [0041]    In some configurations, the insert includes a lubricant bore. 
         [0042]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0043]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0044]      FIG. 1  is a cross-sectional view of a compressor having connecting rods according to the principles of the present disclosure; 
           [0045]      FIG. 2  is a plan view of one of the connecting rods of  FIG. 1 ; 
           [0046]      FIG. 3  is a partial perspective view of the connecting rod; 
           [0047]      FIG. 4  is a partial plan view of another connecting rod according to the principles of the present disclosure; 
           [0048]      FIG. 5  is a partial perspective view of the connecting rod of  FIG. 4 ; 
           [0049]      FIG. 6  is a partial plan view of yet another connecting rod according to the principles of the present disclosure; and 
           [0050]      FIG. 7  is a partial plan view of yet another connecting rod according to the principles of the present disclosure. 
       
    
    
       [0051]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0052]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0053]    Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
         [0054]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0055]    When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0056]    Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
         [0057]    Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0058]    With reference to  FIG. 1 , a compressor  10  is provided that can compress a working fluid from a suction pressure to a discharge pressure to cause the working fluid to circulate amongst various components of a climate control system (e.g., a refrigeration system, an air conditioning system or a heat-pump system). The compressor  10  may be a reciprocating compressor and may include a shell  12  and a cylinder head assembly  14 . The shell  12  may house a compression mechanism  16  that may include a crankshaft  18 , one or more pistons  22 , and one or more connecting rods  26 . The shell  12  may include one or more cylinders  30  and first and second bearing housings  34 ,  36 . The pistons  22  are reciprocatingly received in respective cylinders  30  such that compression chambers  32  are defined within the cylinders  30  between the pistons  22  and the cylinder head assembly  14 . The first and second bearing housings  34 ,  36  rotatably support the crankshaft  18 . A motor  38  may drive rotation of the crankshaft  18  relative to the shell  12 . The motor  38  could be disposed inside of the shell  12  or outside of the shell  12 . The crankshaft  18  can be formed from iron, steel, aluminum, titanium, or a polymeric material, for example, or any other suitable material. 
         [0059]    Referring now to  FIGS. 1-3 , each of the connecting rods  26  includes a body  40 , a first bushing  42  and a second bushing  44 . The body  40  and the first and second bushings  42 ,  44  can be formed from aluminum, steel, iron, titanium, an unleaded bearing copper alloy, or a polymeric material, for example, or any suitable material. The body  40  is disposed between and interconnects the first and second bushings  42 ,  44 . The first and second bushings  42 ,  44  define first and second aperture  46 ,  48 , respectively. The first aperture  46  may have a smaller diameter than the second aperture  48 . The first bushing  42  may be integrally formed with the body  40  and may rotatably engage a piston pin  50  ( FIG. 1 ) of a corresponding piston  22 . 
         [0060]    The second bushing  44  may be formed by first and second bushing halves  52 ,  54 . The first and second bushing halves  52 ,  54  include first and second arched driving surfaces  58 ,  60 , respectively, that cooperate to define the second aperture  48  and rotatably engage a bearing journal  56  ( FIG. 1 ) of a corresponding crank throw  62  of the crankshaft  18 . The first bushing half  52  can be integrally formed with the body  40  and the first bushing  42 . The second bushing half  54  can be removably fastened to the first bushing half  52  by one or more bolts  64  and/or other fasteners to selectively couple and uncouple the connecting rod  26  to the corresponding crank throw  62 . 
         [0061]    The first bushing half  52  may include a recess  66  formed in the first arched surface  58 . A lubricant bore  68  may extend through a portion of the first bushing half  52  to the recess  66 . In some configurations, the lubricant bore  68  may extend through a portion of the body  40  of the connecting rod  26 . In some configurations, the lubricant bore  68  may extend from the first bushing  42  to the second bushing  44 . In the example depicted in  FIGS. 2 and 3 , the recess  66  spans the entire axial thickness T of the first bushing half  52 . That is, sidewalls  70  of the recess  66  can extend in an axial direction (i.e., in a direction parallel to a rotational axis of the second bushing  44 ) through opposing axial ends  71 ,  73  of the second bushing  44 . In other configurations, the recess  66  could span only a portion of the axial thickness T of the first bushing half  52 . 
         [0062]    In the particular example depicted in  FIGS. 2 and 3 , one of the sidewalls  70  of the recess  66  may be aligned with a longitudinal axis A ( FIG. 2 ) of the connecting rod  26  (i.e., a centerline or axis of symmetry of the connecting rod  26 ), and the other side wall  70  may be angularly spaced about thirty degrees) (30° apart from the longitudinal axis A. In other configurations, the positioning of either or both of the sidewalls  70  relative to the longitudinal axis A could vary from the configuration shown in  FIGS. 2 and 3 . That is, either of both of the side walls  70  could be angularly spaced apart from the longitudinal axis A by less than or greater than thirty degrees. For example, the configuration shown in  FIG. 6  depicts the recess  66  having one sidewall  70  aligned with the longitudinal axis A and another sidewall  70  angularly spaced apart from the longitudinal axis A by sixty degrees (60°). 
         [0063]    In other examples, one sidewall  70  can be spaced apart from the longitudinal axis A by about thirty or sixty degrees (or any other suitable angle) in a first direction, and the other sidewall  70  can be spaced apart from the longitudinal axis A by about thirty or sixty degrees (or any other suitable angle) in a second direction opposite the first direction. That is, the recess  66  can be generally centered on the longitudinal axis A, as shown in  FIG. 7 . Such an arrangement may be particularly beneficial in three-phase compressor applications in which the crankshaft  18  can rotate in either direction depending on the operational mode of the compressor  10 . 
         [0064]    Furthermore, while the sidewalls  70  are depicted in  FIGS. 2 and 3  as being planar and extending in parallel directions, in some configurations, either or both of the sidewalls  70  could have any desired shape and could extend in any desired direction. For example,  FIGS. 4 and 5  illustrate an exemplary configuration in which the sidewalls  70  are curved and extend in serpentine paths. The size, shape and location of the recess  66  may be chosen to correspond to an area of the second bushing  44  that is subjected to particularly high loading during operation of the compressor  10  and/or an area of the second bushing  44  that is subject to particularly high wear forces. 
         [0065]    An end wall  72  of the recess  66  can be a curved surface that is concentric with the first arched surface  58 , as shown in  FIGS. 2, 3 and 6 . In other configurations, the end wall  72  can be a substantially flat, planar surface, as shown in  FIGS. 4 and 5 . It will be appreciated that the end wall  72  could have any other shape or configuration. 
         [0066]    As shown in  FIGS. 2-6 , an insert  74  may be received in the recess  66 . The insert  74  can include a lubricant bore  76  that may be aligned with and in fluid communication with the lubricant bore  68  extending through the first bushing half  52 . The insert  74  can have a substantially identical complementary shape as the recess  66  in which the insert  74  is received. In some configurations, the shape of the insert  74  can vary from that of the recess  66 . The insert  74  can be shaped and sized for a press fit or interference fit with the recess  66 . Additionally or alternatively, the insert  74  could be adhesively bonded within the recess  66 . A bearing surface  78  of the insert  74  can have the same radius of curvature as the first and second arched surfaces  58 ,  60  so that when the insert  74  is fully installed in the recess, the bearing surface  78  of the insert is flush with the first arched surface  58 . The insert  74  can be formed from a material having a high lubricity relative to the material(s) of the rest of the second bushing  44 . For example, the insert  74  can be formed from a polymeric material (including polymeric materials with or without reinforcement and/or with or without anti-wear additive, or polymer composites containing anti-wear and/or lubricating additives such as fibrous materials, ZnS, CaF 2 , graphite, PTFE or MoS 2 , for example), a metallic material (e.g., an unleaded metallic bearing alloy or any other alloy having suitable lubricity), a composite material, or any suitable high lubricious, solid material. In some configurations, the insert  74  can be formed from a thermoplastic or thermoset resin. In some configurations, the material of the insert  74  may or may not have lubricating additives and/or reinforcement additives. 
         [0067]    Exemplary heat-resistant thermoplastic resins may include but are not limited to those from the polyaryletherketone (PAEK) family (such as polyaryletherketone (PAEK), polyetherketone (PEK), Polyetheretherketone (PEEK), polyetheretheretherketone (PEEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), polyetherketoneetheretherketone (PEKEEK), polyetheretherketoneetherketone (PEEKEK), and combinations thereof), polyphenylene sulfide (PPS), and Polyphthalamide (PPA). Exemplary heat resistant thermoset resins may include, but are not limited to, polyimide (PI), polyamideimide (PAI), polyester, vinylester, and epoxy resins. Exemplary lubricating additives may include, but are not limited to, graphite, graphene, molybdenum disulfide (MoS2), polytetrafluoroethylene (PTFE), tungsten disulfide (WS2), hexagonal boron nitride, carbon nanotubes, carbon fiber, polybenzimidazole, and combinations thereof. Exemplary reinforcement additives may include, but are not limited to, glass fiber, carbon fiber, aramid fiber, and combinations thereof. In some configurations, the inserts  74  may be formed from polyimide (PI) containing graphite (e.g., DuPont Vespel SP21). 
         [0068]    In some configurations, the connecting rod  26  can be cast or molded around the insert  74 , thereby locking the insert  74  into the recess  66 . That is, the insert  74  can be placed on or in a die-casting or molding tool (not shown) so that the connecting rod  26  can be cast around the insert  74 . The insert  74  could include one or more pins or protrusions (not shown) that can act as locking features and engage and/or extend into the end wall  72  of the recess  66 . 
         [0069]    The high lubricity of the inserts  74  of the connecting rods  26  provides sufficient local lubricity between the second bushings  44  and the journals  56  of the crankshaft  18  at immediately following a first, initial startup of the compressor  10  after manufacturing or following an extended period (e.g., several months or more) during which the compressor  10  was not operating. That is, the high lubricity of the inserts  74  provides enough local lubricity between the second bushings  44  and the journals  56  at the highest loadbearing portions of the second bushings  44  to preventing binding or seizure of the connecting rods  26  until a normal flow of lubricant can be established through operation of the compressor  10 . Thereafter, the normal flow of lubricant caused by operation of the compressor  10  will provide additional lubrication between the second bushings  44  and the journals  56 . Additionally, the high lubricity of the insert  74  and the positioning of the insert at a location subjected to the highest loading and wear can increase the lifecycle of the connecting rods  26  and reduce wear on the connecting rods  26  and crankshaft  18 . 
         [0070]    While the examples provided above include the recess  66  and insert  74  being in the first bushing half  52  of the second bushing  44 , the connecting rods  26  could additionally or alternatively include one or more recesses and inserts in the second bushing half  54  and/or in the first bushing  42 , for example. Furthermore, in some configurations, the first bushing half  52  could include multiple recesses and inserts. In some configurations, the connecting rods  26  could be one-piece connecting rods (i.e., the first and second bushing halves  52 ,  54  could be integrally formed as a single piece. 
         [0071]    In some configurations, the insert  74  could be received in a recess in an bushing that is a discrete component from the body  40  and/or formed from a different material than the body  40  (i.e., the insert could be received in a recess in a driving surface of a bushing that is received within bushing  42  or  44 ). 
         [0072]    Referring again to  FIG. 1 , operation of the compressor  10  will be described. Rotary motion of the crankshaft  18  (caused by operation of the motor  38 ) is transmitted to the pistons  22  by the connecting rods  26 , thereby causing the pistons  22  to reciprocate within the cylinders  30 . In the particular configuration shown in  FIG. 1 , the pair of pistons  22  reciprocate out-of-phase with each other in linearly alternating directions as the crankshaft  18  rotates. 
         [0073]    Working fluid enters the cylinders  30  during suction strokes of the corresponding pistons  22  (i.e., when the pistons  22  move from a top-dead-center (TDC) position to a bottom-dead-center (BDC) position). When a particular piston  22  is at the TDC position, the crankshaft  18  may rotate approximately one-hundred-eighty degrees (180°) to move the particular piston  22  into the BDC position, thereby causing the piston  22  to move from a location proximate to a top portion of the particular cylinder  30  adjacent the cylinder head assembly  14  to a bottom portion of the cylinder  30  spaced apart from the cylinder head assembly  14 . When one of the pistons  22  is moved into the BDC position from the TDC position, the compression chamber  32  corresponding to that piston  22  is placed under a vacuum, which causes suction-pressure working fluid to be drawn into the corresponding cylinder  30 . 
         [0074]    When the piston  22  travel toward the TDC position, the effective volume of the compression chamber  32  is reduced, thereby compressing the working fluid disposed within the compression chamber  32 . At or near the TDC position, the working fluid may exit the cylinders  30  and enter a discharge chamber  80  in the cylinder head assembly  14 . From the discharge chamber  80 , the working fluid may be expelled from the compressor  10  through a discharge port  82  in the shell  12 , for example. 
         [0075]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.