Abstract:
A compressor includes a shell, a compression mechanism, a motor, a base member, and a mounting foot. The compression mechanism is disposed within the shell and the motor is drivingly engaged with the compression mechanism. The base member is coupled to the shell and a mounting foot is fixed to the base member. The mounting foot includes a mounting aperture extending therethrough and a slot intersecting the aperture that attenuates vibrations within an operating frequency range of the compressor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/845,299, filed on Sep. 18, 2006. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to compressors, and more specifically to noise attenuation mounting structures for compressors. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Operation of a compressor may result in noise generation from moving parts associated therewith, such as the motor and compression mechanism. Compressor noise may be transmitted through the air and/or to a structure engaged with the compressor. The structure of the compressor including the shell and mounting portions may contribute to noise generation by transmitting the noise generated by the moving parts and even amplifying the noise. 
     SUMMARY 
     A compressor may include a shell, a compression mechanism, a motor, a base member, and a mounting foot. The compression mechanism may be disposed within the shell and the motor may be drivingly engaged with the compression mechanism. The base member may be coupled to the shell and a mounting foot may be fixed to the base member. The mounting foot may include a mounting aperture extending therethrough and a slot intersecting said aperture that attenuates vibrations within an operating frequency range of the compressor. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a sectional view of a compressor according to the present disclosure; 
         FIG. 2  is a perspective view of a base member of the compressor of  FIG. 1 ; 
         FIG. 3  is a alternate base member according to the present disclosure; 
         FIG. 4  is a sectional view of the base member of  FIG. 3 ; 
         FIG. 5  is an alternate base member according to the present disclosure; and 
         FIG. 6  is a refrigeration unit according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     The present teachings are suitable for incorporation in many different types of scroll and rotary compressors, including hermetic machines, open drive machines and non-hermetic machines. For exemplary purposes, a compressor  10  is shown as a hermetic scroll refrigerant-compressor of the low-side type, i.e., where the motor and compressor are cooled by suction gas in the hermetic shell, as illustrated in the vertical section shown in  FIG. 1 . 
     Compressor  10  may include a cylindrical hermetic shell  16 , a compression mechanism  18 , a main bearing housing  20 , a motor assembly  22 , a refrigerant discharge fitting  24 , and a suction gas inlet fitting  26 . The hermetic shell  16  may house the compression mechanism  18 , main bearing housing  20 , and motor assembly  22 . Shell  16  may include an end cap  28  at the upper end thereof, a transversely extending partition  29 , a longitudinally extending intermediate portion  31 , and a lower cover  33 . The portions of shell  16  may be fixed to one another in a variety of ways, such as welding, to seal hermetic shell  16 . The refrigerant discharge fitting  24  may be attached to shell  16  at opening  30  in end cap  28 . The suction gas inlet fitting  26  may be attached to shell  16  at opening  32 . The compression mechanism  18  may be driven by motor assembly  22  and supported by main bearing housing  20 . The main bearing housing  20  may be affixed to shell  16  at a plurality of points in any desirable manner. 
     The motor assembly  22  may generally include a motor  34 , a frame  36  and a drive shaft  38 . The motor  34  may include a motor stator  40  and a rotor  42 . The motor stator  40  may be press fit into frame  36 , which may in turn be press fit into shell  16 . Drive shaft  38  may be rotatably driven by stator  40 . Windings  44  may pass through stator  40 . Rotor  42  may be press fit on drive shaft  38 . A motor protector  46  may be provided in close proximity to windings  44  so that motor protector  46  will de-energize motor  34  if windings  44  exceed their normal temperature range. 
     Drive shaft  38  may include an eccentric crank pin  48  having a flat  49  thereon and one or more counter-weights  50  at an upper end  52 . Drive shaft  38  may include a first bearing portion  53  rotatably journaled in a first bearing  54  in main bearing housing  20  and a second bearing portion  55  rotatably journaled in a second bearing  56  in frame  36 . Drive shaft  38  may include an oil-pumping concentric bore  58  at a lower end  60 . Concentric bore  58  may communicate with a radially outwardly inclined and relatively smaller diameter bore  62  extending to the upper end  52  of drive shaft  38 . The lower interior portion of shell  16  may be filled with lubricating oil. Concentric bore  58  may provide pump action in conjunction with bore  62  to distribute lubricating fluid to various portions of compressor  10 . 
     Compression mechanism  18  may generally include an orbiting scroll  64  and a non-orbiting scroll  66 . Orbiting scroll  64  may include an end plate  68  having a spiral vane or wrap  70  on the upper surface thereof and an annular flat thrust surface  72  on the lower surface. Thrust surface  72  may interface with an annular flat thrust bearing surface  74  on an upper surface of main bearing housing  20 . A cylindrical hub  76  may project downwardly from thrust surface  72  and may include a journal bearing  78  having a drive bushing  80  rotatively disposed therein. Drive bushing  80  may include an inner bore in which crank pin  48  is drivingly disposed. Crank pin flat  49  may drivingly engage a flat surface in a portion of the inner bore of drive bushing  80  to provide a radially compliant driving arrangement. 
     Non-orbiting scroll  66  may include an end plate  82  having a spiral wrap  84  on lower surface  86  thereof. Spiral wrap  84  may form a meshing engagement with wrap  70  of orbiting scroll  64 , thereby creating an inlet pocket  88 , intermediate pockets  90 ,  92 ,  94 ,  96 , and outlet pocket  98 . Non-orbiting scroll  66  may have a centrally disposed discharge passageway  100  in communication with outlet pocket  98  and upwardly open recess  102  which may be in fluid communication via an opening  103  in partition  29  with a discharge muffler chamber  104  defined by end cap  28  and partition  29 . 
     Non-orbiting scroll  66  may have in the upper surface thereof an annular recess  105  having parallel coaxial side walls in which is sealingly disposed for relative axial movement an annular floating seal  107  which serves to isolate the bottom of recess  105  from the presence of gas under suction and discharge pressure so that it can be placed in fluid communication with a source of intermediate fluid pressure by means of a passageway  109 . A spring  111  may urge floating seal  107  upward to maintain a sealing engagement. Non-orbiting scroll  66  may, therefore, be axially biased against orbiting scroll  64  by the forces created by discharge pressure acting on the central portion of scroll  66  and those created by intermediate fluid pressure acting on the bottom of recess  105 . 
     Compressor  10  may use a dual pressure balancing scheme to axially balance non-orbiting scroll  66  with floating seal  107  being used to separate the discharge gas pressure from the suction gas pressure. A solenoid valve  113  may be used to open and close a passageway  115  located within non-orbiting scroll  66 . Passageway  115  extends from the bottom of recess  105  which is at intermediate pressure during operation of compressor  10  to the area of compressor  10  which contains suction gas at suction gas pressure. 
     Relative rotation of the scroll members  64 ,  66  may be prevented by an Oldham coupling, which may generally include a ring  108  having a first pair of keys  110  (one of which is shown) slidably disposed in diametrically opposed slots  112  (one of which is shown) in non-orbiting scroll  66  and a second pair of keys (not shown) slidably disposed in diametrically opposed slots in orbiting scroll  64 . 
     With additional reference to  FIG. 2 , lower cover  33  may include an upper portion  200  having a skirt  202  extending from a perimeter thereof. Skirt  202  may extend at an angle relative to upper portion  200 . In the present example, skirt  202  extends at an angle of approximately 90 degrees relative to upper portion  200 . Upper portion  200  may include a central recessed portion  204  surrounded by a vertically extending annular ridge  206  having a flange portion  208  extending radially outwardly therefrom. Flange portion  208  may have a generally planar body extending generally perpendicular to shell intermediate portion  31 . Upper portion  200  may further include a plurality of mounting feet  210  extending radially outwardly from flange portion  208 . Mounting feet  210  may include apertures  212  therethrough for securing lower cover  33 , and therefore compressor  10 , to a base (discussed below). 
     Upper portion  200  may include a plurality of slots  214  therethrough. Slots  214  may be disposed symmetrically about upper portion  200 . Slots  214  may extend radially outwardly relative to central recessed portion  204  and may extend to the perimeter of upper portion  200 . More specifically, slots  214  may intersect apertures  212  in mounting feet  210 . A first portion  216  of slot  214  may extend from aperture  212  to the perimeter of upper portion  200  and a second portion  218  of slot  214  may extend from aperture  212  radially inwardly toward central recessed portion  204 . 
     Slots  214  may have a width up to the diameter of aperture  212 . Slots  214  may shift lower cover natural frequencies away from undesirable frequencies. For example, slots  214  may reduce 800 Hz ⅓ octave band sound levels. Slots  214  may extend along a majority of mounting feet  210 . More specifically, slots  214  may extend up to the entire distance between an outer perimeter of a mounting foot  210  to intermediate portion  31  of shell  16 . 
     An alternate lower cover  333  is shown in  FIGS. 3 and 4 . Lower cover  333  may include an upper portion  300  having a skirt  302  extending from a perimeter thereof. Skirt  302  may extend at an angle relative to upper portion  300  and may extend a length (L 1 ) of between 3 and 5 times a material thickness (T) of lower cover  333 . Upper portion  300  may include a central recessed portion  304  surrounded by a vertically extending annular ridge  306  having a first flange portion  308  extending radially outwardly therefrom. Vertically extending annular ridge  306  may have a height (L 2 ) greater than material thickness (T). Flange portion  308  may have a generally sloped body extending at an angle (θ) of between 20 and 60 degrees relative to annular ridge  306 . First flange portion  308  may extend a distance (L 3 ) of between 2 and 6 times material thickness (T) above skirt  302 . A second flange portion  309  may extend from and generally surround first flange portion  308 . Second flange portion  309  may be generally planar and may have a plurality of mounting feet  310  extending radially outwardly therefrom. Mounting feet  310  may include apertures  312  therethrough for securing lower cover  333  to a base (discussed below). 
     Lower cover  333  may have a generally square shape with both first and second flange portions  308 ,  309  having generally square perimeters. As seen in  FIG. 3 , mounting feet  310  may extend from each of the corners of second flange portion  309 . As a result of the features mentioned above, lower cover  333  vibration attenuation may be improved. More specifically, these features may push the natural frequency of lower cover  333  higher, as well as changing the mode shape thereof. For example, the sloped profile of flange portion  308  may stiffen mounting feet  310  and raise the natural frequency of lower cover  333  (ex: from 800 Hz to 1250 Hz). The slot geometry discussed below with respect to  FIG. 5  may be used to tune the frequency away from the new frequency (1250 Hz). 
       FIG. 5  is an alternate example of a lower cover  433  generally similar to lower cover  333  with the addition of slots  414 . As such, the description of lower cover  333  may generally apply to lower cover  433 , except as otherwise noted. Lower cover  433  may include an upper portion  400  having a skirt  402  extending from a perimeter thereof. 
     Skirt  402  may extend at an angle relative to upper portion  400 . Skirt  402  may have a length of between 50 and 90 percent of the length of skirt  302 . Upper portion  400  may include a central recessed portion  404  surrounded by a vertically extending annular ridge  406  having a first flange portion  408  extending radially outwardly therefrom. Flange portion  408  may have a generally sloped body extending at an angle relative to vertically extending annular ridge  406 . Flange portion  408  may have a width of 80 to 110 percent of the width of flange portion  308 . 
     The distance between skirts  402  on opposed sides may be greater than the width of flange portion  408  and 90 to 100 percent of the distance between skirts  302  on opposed sides. A second flange portion  409  may extend from and generally surround first flange portion  408 . Second flange portion  409  may be generally planar and may have a plurality of mounting feet  410  extending radially outwardly therefrom. Mounting feet  410  may include apertures  412  therethrough for securing lower cover  433  to a base (discussed below). 
     Upper portion  400  may include a plurality of slots  414  therethrough. Slots  414  may be disposed symmetrically about upper portion  400 . Slots  414  may extend radially outwardly relative to central recessed portion  404  and may extend to the perimeter of upper portion  400 . More specifically, slots  414  may intersect apertures  412  in mounting feet  410 . A first portion  416  of slot  414  may extend from aperture  412  to the perimeter of upper portion  400  and a second portion  418  of slot  414  may extend from aperture  412  radially inwardly toward central recessed portion  404 . Second portion  418  may have a length greater than a material thickness of lower cover  433 , similar to material thickness (T) in  FIG. 4 , and a width generally less than the diameter of aperture  412 . 
     Lower cover  433  may have a generally square shape with both first and second flange portions  408 ,  409  having generally square perimeters. Mounting feet  410  may extend from each of the corners of second flange portion  409 . As a result of the features mentioned above, lower cover  433  vibration attenuation may be improved. More specifically, these features may push the natural frequency of lower cover  433  higher, as well as changing the mode shape thereof. For example, the sloped profile of flange portion  408  may stiffen mounting feet  410  and raise the natural frequency of lower cover  433  (ex: from 800 Hz to 1250 Hz). The slot geometry may be used to tune the frequency of lower cover  433  away from the new frequency (1250 Hz). The features of lower covers  33 ,  333 ,  433  may be used in any combination to achieve a desired noise attenuation. 
     As seen in  FIG. 6 , compressor  10  may be part of a refrigeration unit  500 . Refrigeration unit  500  may include a housing  502  divided into a condensing unit cabinet  504 , a compressor cabinet  506 , and an electronic cabinet  508 . Condensing unit cabinet  504  may house a condensing unit (not shown) and condenser fans  512 . Compressor cabinet  506  may house one or more compressors  10 , as well as a suction header  514  and a discharge header  516 . Electronic cabinet  508  may enclose a controller  518  in an enclosure accessible from the exterior of housing  502 . 
     Compressor  10  may be mounted to a base pan  520  of housing  502  at feet  210 . Sound may be generated from two sources, compressor  10  (air-borne and structure-borne noise) and base pan  520 , or other support structure (structure-borne noise). The pattern of sound generation may be modified by shifting natural frequencies and modifying mode shapes of mounting feet  210  and/or lower cover  33 . This modification may be achieved in a variety of ways. For example, lower cover  33  may be designed in a way such that the natural modes of mounting feet  210  do not match any local or global mode of base pan  520  or any other mounting structures. It is understood that the above description applies equally to lower covers  333 ,  433 . 
     Base pan  520  may include puck-like protrusions, or grommets, (not shown) for engagement with compressor feet  210 . Mounting feet  210  may be bolted to base pan  520  at the grommets. Double studded grommets may lower natural frequencies, while conventional mounting may increase natural frequencies through increased torque on the bolt when mounting lower cover  33  to base pan  520  or other support structure. The presence of any slots, windows or slits may change the boundary conditions of the cavity beneath lower cover  33 , which in turn may change the noise radiation pattern when compressor  10  is mounted to base pan  520 , or some other mounting structure. While described with respect to lower cover  33 , it is understood that the description of the engagement between lower cover  33  and base pan  520  applies equally to lower covers  333 ,  433 . 
     By way of example, internal components of compressor  10  may have 800 Hz ⅓ Octave and 1250 Hz ⅓ Octave natural frequencies. These frequencies may be passed through lower cover  33  and amplified. Using the features described above, the natural frequencies of lower cover  33  may be mismatched relative to the natural frequencies of the internal components of compressor  10  to break the chain of energy.