Patent Abstract:
A modular silencer for use on a compressor or blower mounted on a vehicle. The compressor has an intake port and an exhaust port, and the silencer has an inlet port in communication with the exhaust port of the compressor. The silencer includes a silencer housing and a resonator assembly removably positioned inside the housing. In one embodiment, the compressor includes a compressor housing and a power input shaft protruding from the compressor housing adjacent the air exhaust port. The silencer housing preferably includes a concave portion that at least partially receives the power input shaft. The silencer housing can also include a groove on the inner surface, and the resonator assembly can be at least partially positioned in the groove. Preferably, the resonator assembly includes a resonator plate, a plurality of resonator pipes extending through the plate, and a reinforcing flange coupled between at least two of the resonator pipes.

Full Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to mobile vehicles, such as trucks and trailers, road transport vehicles, rail transport vehicles, and the like that transport bulk goods and, more specifically, to discharge silencers used on compressors mounted on such vehicles. 
       BACKGROUND OF THE INVENTION 
       [0002]    Vehicle-mounted air compressors are used to unload dry and liquid bulk goods from large pressurized vessels and container trucks and trailers. The technique involves pumping compressed air into the top end of a vessel/container while opening a valve in a lower end of the vessel/container to allow the dry or liquid goods to be conveyed out of the mobile vessel/container and into a different storage unit. Examples of dry products conveyed out of vehicles using this technique include flour, wheat, cereal, cornstarch, synthetic powder, granulated products, cement, limestone, and fly ash. Examples of liquid products conveyed out of vehicles using this technique include chemicals, solvents, food, liquid sugar, molasses, and bitumen. 
         [0003]    When a compressor is mounted on a vehicle, the compressor is commonly driven off of the engine that drives the vehicle. As a result, the speed of the compressor is typically proportional to the speed at which the vehicle&#39;s engine drives a compressor. The vehicle engine speed can vary depending on the size and type of engine, and on the vehicle and environment in which the compressor is used. 
         [0004]    Noise from the compressor is a concern to vehicle operators because of the existing health and safety regulations, and especially in situations where the vehicles are used to unload dry and liquid goods in densely-populated areas. Specifically, pressure pulsations generated at the discharge and/or suction port of a compressor is a major contributor to the total noise of the compressor. Pressure pulsations propagate through the entire piping system and radiate through the walls of the pipes. Silencers are commonly used to reduce the severity of these pressure pulsations. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a modular silencer for use on a compressor (e.g., a screw compressor) mounted on a vehicle (e.g., a tractor, truck, or trailer). The compressor has an intake port and an exhaust port, and the silencer has an inlet port in communication with the exhaust port of the compressor. The silencer includes a housing and a resonator assembly removably positioned inside the housing. The housing includes a removable portion (e.g., a side cover) that facilitates access to and removal of the resonator assembly. 
         [0006]    In one embodiment, the compressor includes a compressor housing and a power input shaft protruding from the compressor housing adjacent the air exhaust port. In this embodiment, the silencer housing preferably includes a concave portion that at least partially receives the power input shaft. 
         [0007]    The silencer housing can also include a groove on the inner surface, and the resonator assembly can be at least partially positioned in the groove. Preferably, the resonator assembly includes a resonator plate and a plurality of resonator pipes extending through the plate. In this embodiment, the resonator plate is slidably positioned in the groove. If desired, a reinforcing flange can be coupled between at least two of the resonator pipes. 
         [0008]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a tractor-trailer having a compressor shown schematically. 
           [0010]      FIG. 2  is an exploded view of a vehicle-mounted compressor assembly having a compressor and a discharge silencer. 
           [0011]      FIG. 3  is an upper perspective view of the discharge silencer of  FIG. 2 . 
           [0012]      FIG. 4  is a lower perspective view of the discharge silencer of  FIG. 2 . 
           [0013]      FIG. 5  is another upper perspective view of the discharge silencer of  FIG. 2 . 
           [0014]      FIG. 6  is a bottom view of the discharge silencer of  FIG. 2 . 
           [0015]      FIG. 7  is an exploded perspective view of the discharge silencer of  FIG. 2 . 
           [0016]      FIG. 8  is a section view taken along line  8 - 8  in  FIG. 6 . 
           [0017]      FIG. 9  is a section view taken along line  9 - 9  in  FIG. 6 . 
           [0018]      FIG. 10  is a perspective view of a resonator assembly from the discharge silencer of  FIG. 7 . 
           [0019]      FIG. 11  is a bottom view of the resonator assembly of  FIG. 10 . 
           [0020]      FIG. 12  is a perspective view of an alternative discharge silencer. 
           [0021]      FIG. 13  is an exploded perspective view of the discharge silencer of  FIG. 13 . 
           [0022]      FIG. 14  is a perspective view of an inlet housing of the silencer in  FIG. 12 . 
           [0023]      FIG. 15  is a perspective view of an outlet housing of the silencer in  FIG. 12 . 
           [0024]      FIG. 16  is a section view taking along line  16 - 16  in  FIG. 12 . 
           [0025]      FIG. 17  is a section view taken along line  17 - 17  in  FIG. 12 . 
           [0026]      FIG. 18  is a section view taken along line  18 - 18  in  FIG. 12 . 
           [0027]      FIG. 19  is a section view taken along line  19 - 19  in  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]      FIG. 1  illustrates a vehicle in the form of a tractor-trailer  20  having a storage container  22  for holding bulk goods and a compressor assembly  24  for providing pressurized air to the container. It should be noted that while the invention is shown and described in association with the tractor-trailer  20 , other vehicles (e.g., railroad cars) could also be employed with the invention. Referring to  FIG. 2 , the compressor assembly  24  includes a compressor  26  and a silencer  28 . The compressor  26  includes a compressor housing  30  defining an air intake port  32  and an air exhaust port  34 . A power input shaft  36  extends out of the compressor housing  30  to provide a means for driving the compressor  26  (e.g., by an external source, such as an auxiliary drive from the tractor). The illustrated compressor  26  is a CS1200 oil-free screw compressor, available from G.H.H. Rand GmbH of Oberhausen, Germany. Of course other constructions could employ other types of compressors (e.g., rotary, piston, fan, sliding vane, etc.) or blowers (e.g., rotary axial blower, etc.) in place of or in conjunction with the illustrated compressor. 
         [0029]    The silencer  28  is mounted at the exhaust port  34  of the compressor  26 . Of course, other constructions could employ a silencer  28  at the inlet port in place of, or in conjunction with the silencer  28 . The silencer  28  includes a silencer housing  38  having an inlet port  40  for receiving compressed air from the compressor  26  and an outlet port  42  for providing dampened, compressed air to a desired conduit  44 . A resonator assembly  46  is positioned inside the silencer housing  38 , and the silencer housing  38  includes a removable side cover  48  enclosing the resonator assembly  46  within the silencer housing  38 . The side cover  48  includes a series of holes  50  that are adapted to be aligned with corresponding threaded holes  52  in the silencer housing  38 , and a series of corresponding bolts  54  and washers  56  can be used to secure the side cover  48  to the rest of the silencer housing  38  ( FIG. 7 ). The removability of the side cover  48  facilitates access to the resonator assembly  46 , which allows the resonator assembly  48  to be easily removed and replaced, as described below in more detail. 
         [0030]    The silencer housing  38  is designed to be used with the compressor  26  illustrated in  FIG. 2 . The inlet port  40  of the silencer housing  38  is dimensioned to mate with the compressor exhaust port  34 . Seven holes  58  on the silencer housing  38  are dimensioned to be aligned with seven corresponding threaded holes  60  on the compressor housing  30 , and seven corresponding bolts  62  and washers  64  are used to secure the silencer housing  38  to the compressor housing  30  ( FIGS. 2 and 7 ). If desired, a gasket (not shown) can be positioned between the silencer housing  38  and the compressor housing  30 . 
         [0031]    The silencer housing  38  includes a concave portion  66  positioned immediately above and adjacent to the silencer inlet port  40 . The concave portion  66  is designed to provide clearance between the silencer housing  38  and the power input shaft  36  (and/or its associated coupling, not shown) on the compressor  26 , as best shown in  FIGS. 2 and 9 . 
         [0032]    The silencer housing  38  further includes an access port  68  ( FIGS. 4 and 7 ) that provides access to the inside of the silencer housing  38 . When the silencer  28  is installed on the compressor  26 , the access port  68  is covered by an access cover  70 , and an access gasket  72  is positioned between the access cover  70  and the silencer housing  38  to provide a seal ( FIG. 7 ). A series of bolts  74  and washers  76  secure the access cover  70  to the silencer housing  38 . 
         [0033]    An outlet valve  80 , outlet gasket  82 , and outlet coupling  84  are secured at the outlet port  42  by a series of bolts  86  and washers  88  ( FIG. 7 ). The outlet valve  80  is a normally-closed, gravity-biased flapper valve that closes the outlet port  42  when the compressor  26  is not operating. The outlet coupling  84  facilitates attachment of the conduit  44  for directing pressurized air flow out of the silencer  28 . 
         [0034]    The resonator assembly  46  includes a resonator plate  90  and a series of resonator tubes  92  extending through the resonator late  90 . The resonator plate  90  is removably positioned in the silencer housing  38  and can be accessed by removal of the side cover  48 , as described above. Three sides of the silencer housing  38  include a recessed groove  94  that is dimensioned to receive the resonator plate  90 . The side cover  48  also includes a groove  95  that is dimensioned to receive the resonator plate  90 . The resonator plate  90  is designed to be slid into the groove  94 , and will be maintained in that position upon securing the side cover  48  to the silencer housing  38 . The interface between the resonator plate  90  and the silencer housing  38  and side cover  48  is designed to direct substantially all of the air flow through the resonator tubes  92 . 
         [0035]    In the illustrated embodiment, the resonator assembly  46  includes eight resonator tubes  92  extending through the resonator plate  90  with more or fewer tubes being suitable for use in other constructions. A series of reinforcing flanges  96  are secured between adjacent resonator tubes  92 . Preferably, the resonator plate  90 , resonator tubes  92 , and reinforcing flanges  96  are welded at their junctures, but any suitable securing technique can be used. Alternatively, the resonator assembly  46  could be cast or molded as a single piece. 
         [0036]    In use, the silencer  28  is secured to the compressor  26  such that the exhaust port  34  of the compressor  26  is aligned with the inlet port  40  of the silencer  28 . The compressed air passes through the silencer housing  38  until it reaches the resonator assembly  46 . At this point, the compressed air flow is forced to pass through the resonator tubes  92 , at which time pressure pulsations in the air flow will be dampened. The dampened air flow then passes through the outlet port  42  and can be used as needed. 
         [0037]    One aspect of the present invention is the fact that the resonator assembly  46  can be replaced in order to tune the silencer  28  to a specific compressor. In order to do this, the side cover  48  of the silencer housing  38  is removed, and the resonator assembly  46  is slid out of the silencer housing  38 . A different resonator assembly (e.g., having the same sized resonator plate but different sized or oriented resonator tubes) can be slid into the silencer housing  38 . The resonator tubes of the different resonator assembly are preferably sized, positioned, and oriented to be tuned to the characteristics of the compressor to which the silencer  28  is attached, thereby enhancing the dampening effects. 
         [0038]    An alternative discharge silencer  100  is illustrated in  FIGS. 12-19 . The alternative silencer  100  includes an inlet housing  102  and an outlet housing  104  that are secured together by a series of bolts  106  passing through holes  108  in the outlet housing  104  and engaged into threaded holes  110  in the inlet housing  102 . 
         [0039]    The inlet housing  102  includes an inlet port  112  that is designed to be aligned with an exhaust port of a compressor. The inlet housing  102  further includes a flange  114  having a series of circumferentially-spaced holes  116  spaced around the inlet port  112 . The holes  116  are positioned relative to each other such that the inlet housing  102  can be mounted to the corresponding compressor in any one of multiple rotational orientations. For example, in the illustrated embodiment, the holes  116  are equally spaced from each other, and thus the inlet housing  102  can be mounted to the corresponding compressor in any one of eight different rotational orientations. 
         [0040]    Referring to  FIGS. 13 ,  14  and  16 , the inlet housing  102  includes an engagement face  118  that is designed to be clamped against the outlet housing  104 . The illustrated engagement face  118  includes an undercut region  120  that facilitates insertion of fasteners through the two openings  124  that are aligned with the undercut region  120 . The inlet housing  102  defines two substantially cylindrical inlet cavities  126  that communicate with the inlet port  112  via inlet channels  127  ( FIG. 16 ). The engagement face  118  further includes a recessed edge  128  around each of the inlet cavities  126 . 
         [0041]    Referring to  FIGS. 13 ,  15  and  17 , the outlet housing  104  defines two substantially cylindrical outlet cavities  130  that will be aligned with the two inlet cavities  126  when the inlet housing  102  and outlet housing  104  are secured together. The outlet housing also includes an engagement face  132  designed to be clamped against the engagement face  118  of the inlet housing  102 . Similar to the inlet housing  102 , the engagement face  132  of the outlet housing  104  includes a recessed edge  134  around each of the outlet cavities  130 . The outlet housing  104  further includes a back cut region  136  that facilitates access to one of the holes  108  in the outlet housing  104 . The outlet housing  104  further includes an outlet port  138  that is designed to be aligned with a conduit (now shown) for providing pressurized air to a desired location. The outlet port  138  communicates with the outlet cavities  130  via outlet channels  139  ( FIG. 17 ). An outlet flange  140  is positioned around the outlet port  138  and includes a series of circumferentially-spaced holes  142  that facilitate attachment of the outlet flange  140  to the desired conduit. 
         [0042]    Referring to  FIGS. 13 ,  18  and  19 , two resonator assemblies  150  are designed to fit inside the inlet housing  102  and outlet housing  104 . Each resonator assembly  150  includes a resonator plate  152  designed to fit within one of the recessed edges  128 ,  134  in the inlet housing  102  and outlet housing  104 . Each resonator assembly  150  further includes resonator pipes  154  extending through the resonator plate  152 . In the illustrated embodiment, each resonator assembly  150  includes four resonator pipes  154 , each having a different length. Of course any number of resonator pipes  154  could be employed if desired. In addition, the length of each pipe could be the same or could be different and is selected to tune the pipes  154  to attenuate sound at the desired frequencies. The number and length of the tubes could depend on the type of compressor or blower to which the silencer is attached and whether the silencer is positioned on the intake or discharge side of the compressor or blower. 
         [0043]    Each resonator assembly  105  is held in place by the sandwiching effect between the recessed edges  128 ,  134  of the inlet housing  102  and outlet housing  104 . As a result, each resonator assembly  150  can be removed from the silencer  100  by disassembling the inlet housing  102  from the outlet housing  104 . Similar to the previous embodiment of  FIGS. 1-11 , this facilitates changing the resonator assemblies in order to tune the silencer to the characteristics of the particular compressor to which the silencer is connected. 
         [0044]    In another construction, a middle housing is positioned between the inlet housing  102  and the outlet housing  104  to facilitate the placement of additional resonator assemblies  150 . In this construction, two resonator assemblies  150  can be sandwiched between the middle housing and the inlet housing  102  and two additional resonator assemblies  150  can be positioned between the middle housing and the outlet housing  104 . With the use of additional middle housings, still more resonator assemblies  150  can be employed through the use of additional middle housings if desired. 
         [0045]    In use, the silencer  100  is secured to a compressor (not shown) such that the exhaust port of the compressor is aligned with the inlet port  112  of the silencer  100 . The compressed air passes through the inlet port  112  and divides into the two inlet channels  127  before entering the inlet cavities  126 . The air is then forced through the resonator tubes and into the outlet cavities  130 . From the outlet cavities  130 , the air passes through the outlet channels  139  and out the outlet port  138 , where it can be provided to a conduit (not shown) as desired. 
         [0046]    Various features and advantages of the invention are set forth in the following claims.

Technology Classification (CPC): 5