Abstract:
A diaphragm muffler for quiet operation of a compressor imparting an above atmospheric pressure stream and a below atmospheric pressure stream. The diaphragm muffler including a diaphragm pressure chamber receiving the above atmospheric pressure stream; a diaphragm vacuum chamber receiving the below atmospheric pressure stream; and a flexible diaphragm dividing the diaphragm pressure chamber receiving the above atmospheric pressure stream from the diaphragm vacuum chamber receiving the below atmospheric pressure stream, whereby the above atmospheric pressure stream and the below atmospheric pressure stream cancel each other out via the flexible diaphragm.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application 60/933,675 filed Jun. 8, 2007 under 35 U.S.C. 119(e). This application is incorporated by reference herein as though set forth in full. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The field of this invention relates to devices and methods for quieting systems such as compressor systems, which generate pressure pulses and vacuum pulses during operation. 
       BACKGROUND OF THE INVENTION 
       [0003]    Portable oxygen concentrators are commonly used in the home medical market to treat ambulatory patients with chronic obstructive pulmonary diseases. To make an oxygen concentrator portable, the oxygen concentrator must be as small as possible and weigh as little as possible while delivering sufficient concentrated oxygen gas flow to the ambulatory patient. Because a portable oxygen concentrator is used in a variety of different environments where low noise levels are important (e.g., restaurants, places or worship, libraries), it is important for the portable oxygen concentrator to be quiet during operation. 
         [0004]    Air compressors are used in oxygen concentrators to supply high-pressure feed air to a Pressure Swing Adsorption (PSA) Module or concentrator. Air compressors, especially combined compressor and vacuum pumps, are relatively noisy during operation because pressure and vacuum pulses are generated simultaneously during operation, and these pressure and vacuum pulses generate noise. 
       SUMMARY OF THE INVENTION 
       [0005]    To solve these problems and others, an aspect of present invention involves a compact muffler that reduces sound without the flow losses of tortuous path mufflers or the large size of Helmholtz resonators. The compact muffler is used in devices where a pulsating exhaust stream and a pulsating intake stream, which are at similar pressures, both need to be muffled. The compact muffler includes two chambers separated by a diaphragm wherein vacuum pulses from one stream may be canceled against pressure pulses in another stream by means of the diaphragm which allows pressure and volume to be exchanged between each stream, while not allowing the streams to intermix. 
         [0006]    A further aspect of the invention involves a diaphragm muffler for quiet operation of a compressor, the compressor imparting an above atmospheric pressure stream and a below atmospheric pressure stream. The diaphragm muffler including a diaphragm pressure chamber receiving the above atmospheric pressure stream; a diaphragm vacuum chamber receiving the below atmospheric pressure stream; and a flexible diaphragm dividing the diaphragm pressure chamber receiving the above atmospheric pressure stream from the diaphragm vacuum chamber receiving the below atmospheric pressure stream, whereby the above atmospheric pressure stream and the below atmospheric pressure stream cancel each other out via the flexible diaphragm. 
         [0007]    Another aspect of the invention involves a method of using a diaphragm muffler. The method includes receiving above atmospheric pressure stream in the diaphragm pressure chamber of the diaphragm muffler described immediately above; receiving below atmospheric pressure stream in the diaphragm vacuum chamber; and using the flexible diaphragm for canceling out the above atmospheric pressure stream and the below atmospheric pressure stream without mixing the above atmospheric pressure stream and the below atmospheric pressure stream. 
         [0008]    Further objects and advantages will be apparent to those skilled in the art after a review of the drawings and the detailed description of the preferred embodiments set forth below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a simple schematic of an embodiment of a gas separation device, which is an exemplary system/environment for the diaphragm muffler. 
           [0010]      FIG. 2  is an cross-sectional view of a diaphragm muffler constructed in accordance with an embodiment of the invention. 
           [0011]      FIG. 3A  is perspective view of an embodiment of compressor system with portions of a housing removed, and illustrates another embodiment of diaphragm muffler. 
           [0012]      FIG. 3B  is another perspective view of an embodiment of compressor system with portions of a housing removed, similar to  FIG. 3A . 
           [0013]      FIG. 4  is perspective view of the compressor system of  FIG. 3  with substantially the entire housing shown, and illustrates an external view of the diaphragm muffler. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0014]    With reference to  FIG. 1 , a gas separation device  10  constructed in accordance with an embodiment of the invention will first be described before describing an embodiment of a diaphragm muffler  100 . The gas separation device  10  may include a compressor  20  (e.g., rotary piston air compressor, diaphragm-type air compressor), which may be combination compressor/vacuum generator (hereinafter “compressor”), a Pressure Swing Adsorption (PSA) Module or concentrator  30 , a measurement mechanism  40 , and a flow control mechanism  50 . 
         [0015]    In a preferred embodiment, the gas separation device  10  is a portable oxygen concentrator weighing in the range of 2-20 pounds. An example portable oxygen concentrator system that comprises the gas separation device  10  is shown and described in U.S. Pat. No. 6,691,702, which is hereby incorporated by reference herein as though set forth in full. In particular, the portable oxygen concentrator system  100  and described with reference to  FIGS. 1-16 , and especially  FIGS. 1 ,  2 ,  12 ,  15 , and  16 , may be used as the gas separation device  10 . 
         [0016]    In use, a feed fluid such as ambient air may be drawn into the compressor  20  and delivered under high pressure to the PSA Module  30 . In a preferred embodiment, the compressor  20  is a combination compressor and vacuum pump/generator. The vacuum generator is preferably driven by the same motor as the compressor and is integrated with the compressor. The vacuum generator draws exhaust gas from the PSA module  30  to improve the recovery and productivity of the PSA module  30 . The PSA module  30  separates a desired product fluid (e.g., oxygen) from the feed fluid (e.g., air) and expels exhaust fluid. Characteristics of the product fluid (e.g., flow/purity) may be measured by a measurement mechanism  40 . Delivery of the product fluid may be controlled with the flow control mechanism  50 . 
         [0017]    With reference to  FIG. 2 , an embodiment of a diaphragm muffler  100  for use with the compressor  20  will be described. The diaphragm muffler  100  includes a diaphragm housing  110 , which has curved surfaces to resist flexure due to internal pressure fluctuations and an internal surface that may be lined with sound attenuating material, a pressure inlet  120  and a pressure outlet  130  to conduct pressure fluctuations from the outlet of the compressor  20 , a diaphragm pressure chamber  140  communicating with the pressure inlet  120  and the pressure outlet  130 , a vacuum inlet  150  and a vacuum outlet  160  to conduct vacuum fluctuations from the inlet of the compressor  20 , a diaphragm vacuum chamber  170  communicating with the vacuum inlet  150  and the vacuum outlet  160 , and a diaphragm  180 . The diaphragm muffler volume is substantially the same volume as the compressor volume, about 10 cc for a 30 liter/minute compressor. In a preferred embodiment, the diaphragm muffler volume is less than 30 cc. In a more preferred embodiment, diaphragm muffler volume is less than 20 cc. In a most preferred embodiment, diaphragm muffler volume is less than 15 cc. The diaphragm  180  physically separates the pressure gases and the vacuum gases, and allows the pressure fluctuations from a high pressure portion of the compressor  20  to cancel out the pressure fluctuations from the vacuum portion of the compressor  20 . The diaphragm material should be flexible and thin, so that it reacts to pressure fluctuations in the air and it should be long lasting. Silicone rubber, approximately 1 mm thick is ideal. An interior wall surface of diaphragm housing  110  and opposite sides of diaphragm  180  define the diaphragm pressure chamber  140  and the diaphragm vacuum chamber  170 . 
         [0018]    Conduits (not shown) to and from the compressor  20  are configured to have lengths and diameters that create appropriate delays so that the pressure and vacuum pulsations cancel out in the diaphragm muffler  100  to the greatest possible degree. Preferably the inlet and outlet conduits are directed toward the diaphragm  180  to maximize the movement of the diaphragm and thereby the attenuation of the pulsations. 
         [0019]    The diaphragm muffler  100  will now be described in use. During operation of the compressor  20  (combination compressor/vacuum generator), the vacuum generator draws exhaust gas (exhaust stream) from the PSA module  30  in pulses. This pulsating exhaust stream below atmospheric pressure enters the diaphragm vacuum chamber  170  via the vacuum inlet  150  and exits the diaphragm vacuum chamber  170  via the vacuum outlet  160 . Simultaneously, feed fluid (intake stream) under high pressure is delivered in pulses by the compressor  20  to the PSA module  30 . This pulsating pressure stream above atmospheric pressure enters the diaphragm pressure chamber  140  via the pressure inlet  120  and exits the diaphragm pressure chamber  140  via the pressure outlet  130 . Pressure fluctuations through the diaphragm pressure chamber  140  cancel out pressure fluctuations through the diaphragm vacuum chamber  170  via the diaphragm  180 , which physically separates the pressure gases and the vacuum gases. Thus, in the diaphragm muffler  100 , to enable quieter operation of the compressor  20 , the pulsating exhaust stream and the pulsating intake stream, which are at similar pressures, cancel each other out via without mixing the streams via the diaphragm. 
         [0020]      FIGS. 3A ,  3 B, and  4  are perspective views of an embodiment of compressor system  200  including a combination compressor/vacuum generator (hereinafter “compressor”)  220 , and a compressor system housing  230 . The compressor system housing  230  includes a diaphragm muffler  300  similar to the diaphragm muffler  100  describe above with respect to  FIG. 2 . The diaphragm muffler  300  includes a diaphragm housing  310  that is integral with the compressor system housing  230 , a pressure inlet  320  and a pressure outlet  330  to conduct pressure fluctuations from the outlet of the compressor  220 , a diaphragm pressure chamber  340  communicating with the pressure inlet  320  and the pressure outlet  330 , a vacuum inlet  350  and a vacuum outlet  360  to conduct vacuum fluctuations from the outlet of the vacuum pump of compressor  20 , a diaphragm vacuum chamber  370  communicating with the vacuum inlet  350  and the vacuum outlet  360 , and a diaphragm  380 . The diaphragm muffler  300  is used in a similar manner as the diaphragm muffler  100  described above, and, therefore, the use of the diaphragm muffler  300  will not be described in further detail. 
         [0021]    Accordingly, the diaphragm muffler  100 ,  300  is a compact muffler that reduces sound by having the pulsating exhaust stream and the pulsating intake stream, which are at similar pressures, cancel each other out without mixing the streams. 
         [0022]    The above figures may depict exemplary configurations for the invention, which is done to aid in understanding the features and functionality that can be included in the invention. The invention is not restricted to the illustrated architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, although the invention is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features and functionality described in one or more of the individual embodiments with which they are described, but instead can be applied, alone or in some combination, to one or more of the other embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus the breadth and scope of the present invention, especially in the following claims, should not be limited by any of the above-described exemplary embodiments. 
         [0023]    Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as mean “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; and adjectives such as “conventional,” “traditional,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, a group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. Furthermore, although item, elements or components of the disclosure may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent.