Abstract:
A scroll machine is provided with a muffler mounted to the fixed scroll of the scroll machine for improved sound attenuation.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to scroll-type machines. More particularly, the present invention relates to a scroll-type compressor incorporating a muffler assembly mounted to the non-orbiting scroll within the discharge chamber of the compressor. 
     2. Background and Summary of the Invention 
     Scroll machines in general, and particularly scroll compressors, are often disposed in a hermetic shell which defines a chamber within which is disposed a working fluid. it partition within the shell often divides the chamber into a discharge pressure zone and a suction pressure zone. In a low-side arrangement, a scroll assembly is located within the suction pressure zone for compressing the working fluid. Generally, these scroll assemblies incorporate a pair of intermeshed spiral wraps, one or both of which are caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as they travel from an outer suction port towards a center discharge port. An electric motor is normally provided which operates to cause this relative orbital movement. 
     The partition within the shell allows compressed fluid exiting the center discharge port of the scroll assembly to enter the discharge pressure zone within the shell while simultaneously maintaining the integrity between the discharge pressure zone and the suction pressure zone. This function of the partition is normally accomplished by a seal which interacts with the partition and with the scroll member defining the center discharge port. 
     The discharge pressure zone of the hermetic shell is normally provided with a discharge fluid port which communicates with a refrigeration circuit or some other type of fluid circuit. In a closed system, the opposite end of the fluid circuit is connected with the suction pressure zone of the hermetic shell using a suction fluid port extending through the shell into the suction pressure zone. Thus, the scroll machine receives the working fluid from the suction pressure zone of the hermetic shell, compresses this working fluid in the one or more moving chambers defined by the scroll assembly, and then discharges the compressed working fluid into the discharge pressure zone of the compressor. The compressed working fluid is directed through the discharge port through the fluid circuit and returns to the suction pressure zone of the hermetic shell through the suction port. 
     Various methods and devices have been developed which function to attenuate or eliminate any noise generated by the operation of the scroll machine. When the scroll machine is used as a compressor in both refrigeration, as well as air conditioning and heat pump applications, it is particularly advantageous to maintain the lowest operational noise level as possible. Accordingly, the continued development of scroll machines and their fluid systems has been directed to reducing the operational noise levels of these machines while still maintaining the extremely efficient operation for which scroll machines are well known. 
     The present invention resides in the discovery that attaching a muffler directly to the fixed scroll of the scroll machine provides surprisingly good sound attenuation. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a vertical sectional view through the center of a scroll compressor which incorporates a muffler assembly in accordance with the present invention; 
     FIG. 2 is a vertical sectional view through the center of a muffler assembly in accordance with a second embodiment of the present invention; 
     FIG. 3 is a vertical sectional view through the center of a muffler assembly in accordance with a third embodiment of the present invention; 
     FIG. 4 is a vertical sectional view through the center of a muffler assembly in accordance with a fourth embodiment of the present invention; 
     FIG. 5 is a cross-sectional view of the cup-shaped muffler according to the first embodiment of the present invention as shown in FIG. 1; 
     FIG. 6 is a cross-sectional view taken through the center of a nut retainer according to the principles of the present invention as shown in FIGS. 1-4; 
     FIG. 7 is a plan view of the nut retainer according to the principles of the present invention as shown in FIGS. 1-4; 
     FIG. 8 is a partial cross-sectional view showing the muffler of the present invention being threadedly connected to the hub of the non-orbiting scroll according to a one piece embodiment of the present invention; 
     FIG. 9 is a cross-sectional view illustrating the muffler of the present invention being press fit with the hub of the non-orbiting scroll according to a second one-piece embodiment of the present invention; and 
     FIG. 10 is a vertical sectional view through the center of a co-rotating scroll compressor which incorporates a muffler assembly in accordance with the present invention; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention is suitable for incorporation with many different types of scroll machines, for exemplary purposes, it will be described herein incorporated in a scroll refrigerant compressor of the general structure illustrated in FIG.  1 . Referring now to the drawings, and in particular to FIG. 1, a compressor  10  is shown which comprises a generally cylindrical hermetic shell  12  having welded at the upper end thereof a cap  14 . Cap  14  is provided with a refrigerant discharge fitting  18  which may have the usual discharge valve therein (not shown). Other major elements affixed to the shell include an inlet fitting  21 , a transversely extending partition  22  which is welded about its periphery at the same point that cap  14  is welded to shell  12 . A discharge chamber  23  is defined by cap  14  and partition  22 . A two-piece main bearing housing  24  and a lower bearing housing  26  having a plurality of radially outwardly extending legs are each secured to the shell  12 . The lower bearing housing  26  locates and supports within shell  12  the two-piece main bearing housing  24  and a motor  28  which includes a motor stator  30 . A crank shaft  32  having an eccentric crank pin  34  at the upper end thereof is rotatably journaled in a bearing  36  in main bearing housing  24  and a second bearing  38  in lower bearing housing  26 . Crank shaft  32  has, at the lower end, a relatively large diameter concentric bore  40  which communicates with a radially outwardly smaller diameter bore  42  extending upwardly therefrom from the top of crankshaft  32 . Disposed in bore  40  is a stirrer  44 . The lower portion of the interior shell  12  defines an oil sump  46  which is filled with lubricating oil. Stirrer  44  and bore  40  act as a pump to pump lubricating fluid up the crank shaft  32  and into bore  40  and ultimately to all of the various portions of the compressor which require lubrication. 
     Crank shaft  32  is rotatably driven by electric motor  28  including motor stator  30 , windings  48  passing therethrough, and a motor rotor  50  press fitted on crank shaft  32  and having upper and lower counterweights  52  and  54 , respectively. 
     The upper surface of the two-piece main bearing housing  24  is provided with a flat thrust bearing surface  56  on which is disposed an orbiting scroll  58  having the usual spiral vane or wrap  60  on the upper surface thereof. Projecting downwardly from the lower surface of orbiting scroll  58  is a cylindrical hub  61  having a journal bearing  62  therein in which is rotatably disposed a drive bushing  36  having an inner bore  66  in which crank pin  34  is drivingly disposed. Crank pin  34  has a flat on one surface which drivingly engages a flat surface (not shown) formed in a portion of bore  66  to provide a radially compliant driving arrangement, such as shown in assignee&#39;s U.S. Pat. No. 4,877,382, the disclosure of which is hereby incorporated herein by reference. An oldham coupling  68  is disposed between orbiting scroll  58  and bearing housing  24 . Oldham coupling  68  is keyed to orbiting scroll  58  and a non-orbiting scroll  70  to prevent rotational movement of orbiting scroll member  58 . Oldham coupling  58  is preferably of the type disclosed in assignee&#39;s U.S. Pat. No. 5,320,506, the disclosure of which is hereby incorporated herein by reference. A floating seal  71  is supported by the non-orbiting scroll  70  and engages a seat portion  73  mounted to the partition  22  for sealingly dividing the intake  75  and discharge  23  chambers. 
     Non-orbiting scroll member  70  is provided having a wrap  72  positioned in meshing engagement with wrap  60  of orbiting scroll  58 . Non-orbiting scroll  70  has a centrally disposed discharge passage  74  defined by a base plate portion  76 . Non-orbiting scroll  70  also includes an annular hub portion  77  which surrounds the discharge passage  74 . A reed valve assembly  78  is provided in the discharge passage  74 . 
     A muffler assembly  80  is affixed directly to the non-orbiting scroll member  70 . The muffler assembly  80  includes a generally cylindrical cup-shaped muffler  82  which is provided with an annular flange  83  at one end thereof (best shown in FIG. 5) and a plurality of apertures  84  opening radially outwardly in a second end thereof. The apertures  84  are preferably located above the partition plate  22 . The flange portion  83  is engaged by a retainer nut  86  which includes a shoulder  88  (best shown in FIGS. 6 and 7) which engages the flange  83  and an externally threaded portion  90  which threadedly engages internally threaded portion  92  of hub  77 , as shown in FIGS. 2-4. The muffler assembly  80  holds the read valve assembly  78  in place, thus, eliminating the need for a read valve nut which is utilized in previous designs. The muffler  82  is connected to the hub  77 . It has been discovered that mounting the muffler  82  to the non-orbiting scroll instead of the partition plate  22  eliminates the transmission of acoustical energy to the partition plate  22  and compressor shell  12 . Furthermore, it is believed the muffler is less susceptible to gas jet-induced vibration due to its stiffer geometry. 
     With reference to FIG. 2, where like reference numerals designate common elements, a second embodiment of the present invention is shown wherein the muffler  82  is provided with internal screens  100  extending across the diameter of the muffler  82 . The internal screens  100  can be soldered to the sidewalls or attached by other known attachment techniques. 
     With reference to FIG. 3, where like reference numerals designate common elements, a third embodiment of the present invention is shown wherein the muffler  82  is provided with a pair of radially extending discharge plates  102  welded to the outer surface of the muffler  82  to radially discharge the gas to act as a reactive muffler. The muffler  82  includes a plurality of apertures  84  which communicate with a space  103  defined between the pair of discharge plates  102 . The compressed gases pass through the muffler  82 , apertures  84  between the discharge plates  102  and into the discharge chamber  23 . 
     With reference to FIG. 4, where like reference numerals designate common elements, a fourth embodiment of the present invention is shown wherein the muffler  82  is provided with internal baffles  104  which extend inward from the walls of the muffler. The internal baffles  104  are arranged in a staggered relationship and act as a reactive muffler. The internal baffles  104  can be welded to the walls of the muffler  82  or attached by other known attachment techniques. 
     It should be noted that although the preferred embodiment discloses a retainer nut for securing the muffler to the non-orbiting scroll  70 , the muffler  82 ′ can also be provided with a one-piece design wherein external threads  110  are provided on the external surface of the open end of the muffler  82 ′ which engage the internal threads  92  on the hub  77  of the non-orbiting scroll  70 , as best shown in FIG.  8 . As an alternative, one-piece muffler  82 ″ can be press fit with the hub  77  of the non-orbiting scroll  70 , as shown in FIG. 9 or can be attached by other known attachment techniques such as brazing or welding. 
     In addition, the present invention can also be implemented on a co-rotating scroll system as shown in FIG.  10 . With reference to FIG. 10, a co-rotating scroll-type compressor  120  is shown in accordance with the present invention. Compressor  120  includes first and second scroll members  124 ,  126  rotatably supported within an outer shell  128  by upper and lower bearing members  130 ,  132  axially offset from each other Upper bearing member  130  is formed in a plate member  135  which also serves to define a discharge chamber  134  into which compressed fluid exiting discharge port  136  in upper scroll is directed via passage  138 . A discharge check valve  140  is also provided overlying discharge port  136 . Lower scroll member  126  is supported within, and rotatable with, a lower housing  142 . An upper housing  144  surrounds upper scroll member  124 . The upper housing  144  is secured to the lower housing  142  and cooperates with lower housing  142  and upper scroll member  124  to define a separating chamber  148 . 
     A passage  152  is provided in upper scroll member  124  extending from separating chamber  148  to an annular recess  154  formed in the outer periphery of an upper cylindrical hub portion  156  of upper scroll member  124 . Annular recess  154  is in fluid communication with a passage  158  provided in upper bearing member  130  and extending radially outward through plate  135 . 
     A solenoid valve  160  is provided and is controlled by a control module (not shown) in response to system conditions sensed by appropriate sensors (also not shown). Solenoid valve  160  includes a first fluid conduit  162  connected to passage  158 , a second fluid line  164  is connected to discharge line  168  and a third fluid line  170  is connected to section line  172 . The above-described co-rotating scroll compressor  120  is fully disclosed in commonly assigned U.S. Pat. No. 5,741,120. The co-rotating scroll compressor  120  is provided with a muffler assembly  180  which is affixed directly to upper scroll member  124  according to the principles of the present invention. The muffler assembly  180  includes a generally cylindrical cup-shaped muffler  182  which is provided with an annular flange  183  at one end thereof and a plurality of apertures  184  opening radially outwardly in a second end thereof. The flange portion  183  is engaged by a retainer nut  186  which includes a shoulder  188  which engages the flange  183  and an externally threaded portion  190  which threadedly engages internally threaded portion  192  of hub  156 . The muffler assembly  180  holds the reed valve assembly  140  in place, thus, eliminating the need for a reed valve retainer nut. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.