Abstract:
A muffler assembly for a pneumatic power tool includes a tube member defining an interior volume. The tube member includes an upper segment and a lower segment. The upper segment defines a first diameter and includes a closed upper end to inhibit fluid communication with the interior volume therethrough, a lower end, a first portion defining a plurality of vents to enable fluid communication with the interior volume therethrough, and a second portion defining a continuous surface to inhibit fluid communication with the interior volume therethrough. The lower segment defines a second diameter greater than the first diameter and includes an upper end in fluid communication with the lower end of the upper segment, a lower end, a first portion defining a plurality of vents to enable fluid communication with the interior volume therethrough, and a second portion defining a continuous surface to inhibit fluid communication with the interior volume therethrough.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of, and priority to, U.S. Provisional Patent Application No. 61/976,431, filed on Apr. 7, 2014, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Technical Field 
         [0003]    The present disclosure relates to power tools and, more particularly, to a muffler for a pneumatic power tool. 
         [0004]    Background of Related Art 
         [0005]    Pneumatic power tools, e.g., ratchets, drills, wrenches, grinders, sanders, and the like, are commonly used in industrial and residential settings. Such tools typically include a hollow handle defining a chamber that provides an inlet and exit conduit for the high pressure air that powers the tool motor. The chamber includes an air intake passage and an air exhaust passage. Each passage extends between the motor and an opening in or near the bottom surface of the handle. The portion of the intake passage located near the handle opening typically includes a standard air coupler or the like. The coupler is adapted to connect to a pressurized air source. The exhaust passage typically opens to the atmosphere. When exhaust air is vented from the power tool, a considerable amount of noise and particulate debris are generated, potentially causing auditory and/or respiratory damage to the operator and others located nearby. 
         [0006]    Although earplugs and facemasks are often available, they are not always used. Numerous attempts have been made by power tool manufacturers to therefore reduce the amount of noise and particles generated by the power tool itself These attempts include designing quieter and cleaner motors and designing power tool components that suppress noise and trap waste prior to expulsion from the power tool. For example, U.S. Pat. No. 5,418,339, which is hereby incorporated herein by reference, describes a pneumatic power tool having an exhaust port filled with a web of nonwoven fibers coated with a binder resin. Other mufflers for pneumatic power tools are disclosed in U.S. Pat. Nos. 7,216,739; 6,926,117; 6,668,971; 6,209,678; and 5,909,016, all of which are hereby incorporated herein by reference. 
         [0007]    Despite advances in muffling technology, such as those detailed in the above-noted U.S. Patents, a continuing need exists for improvements in noise muffling systems that can reduce sound levels and remove entrained contaminates from exhausted air while eliminating or limiting negative effects on performance of the pneumatic tool. 
       SUMMARY 
       [0008]    To the extent consistent, any of the aspects and features described herein may be used in conjunction with any or all of the other aspects and features described herein. 
         [0009]    In accordance with aspects of the present disclosure, a muffler assembly for a pneumatic power tool is provided including a tube member defining an interior volume. The tube member includes an upper segment defining a first diameter and a lower segment defining a second diameter greater than the first diameter. The upper segment includes a closed upper end to inhibit fluid communication with the interior volume therethrough, a lower end, a first portion defining a plurality of vents to enable fluid communication with the interior volume therethrough, and a second portion defining a continuous surface to inhibit fluid communication with the interior volume therethrough. The lower segment includes an upper end in fluid communication with the lower end of the upper segment, a lower end, a first portion defining a plurality of vents to enable fluid communication with the interior volume therethrough, and a second portion defining a continuous surface to inhibit fluid communication with the interior volume therethrough. 
         [0010]    In an aspect of the present disclosure, the muffler assembly further includes a filter panel configured to wrap around both the upper and lower segments of the tube member. 
         [0011]    In another aspect of the present disclosure, at least one flange extends radially outwardly from an exterior surface of the tube member. The at least one flange is configured to define a channel between the filter panel and the exterior surface of the tube member. The at least one flange may extend longitudinally the length of the tube member. 
         [0012]    In still another aspect of the present disclosure, a receptacle is disposed at the lower end of the lower segment of the tube member in fluid communication therewith. In such aspects, a diffuser panel may be disposed within the receptacle. 
         [0013]    In yet another aspect of the present disclosure, the first portion of the upper segment is positioned towards the upper end of the upper segment and the second portion of the upper segment is positioned towards the lower end of the upper segment. Additionally or alternatively, the first portion of the lower segment may be positioned towards the upper end of the lower segment while the second portion of the lower segment is positioned towards the lower end of the lower segment. 
         [0014]    In still yet another aspect of the present disclosure, the first portion of the upper segment extends less than or equal to one-half of a length of the upper segment and/or the first portion of the lower segment extends less than or equal to one-half of a length of the lower segment. 
         [0015]    A pneumatic power tool provided in accordance with aspects of the present disclosure includes a housing and a muffler assembly. The housing defines an inlet passage and an exhaust passage. The muffler assembly is configured for insertion into the exhausted passage of the housing. The muffler assembly may further be configured similar to any of the aspects detailed above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Various aspects and features of the present disclosure are described herein with reference to the drawings wherein: 
           [0017]      FIG. 1  is a perspective exploded view of a muffler assembly provided in accordance with the present disclosure and configured for use with a handgrip of a power tool; 
           [0018]      FIG. 2  is a perspective view of a muffler tube member of the muffler assembly of  FIG. 1 ; 
           [0019]      FIG. 3  is a front view of the muffler tube member of  FIG. 2 ; 
           [0020]      FIG. 4  is a side view of the muffler tube member of  FIG. 2 ; 
           [0021]      FIG. 5  is a bottom view of the muffler tube member of  FIG. 2 ; 
           [0022]      FIG. 6  is a rear view of the muffler tube member of  FIG. 2 ; 
           [0023]      FIG. 7  is a cross-sectional view of the muffler tube member of  FIG. 2  taken across section line “ 7 - 7 ” of  FIG. 6 ; and 
           [0024]      FIG. 8  is a perspective exploded view of a prior art muffler assembly configured for use with a handgrip of a power tool. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Referring initially to  FIG. 8 , a prior art muffler assembly  600  as disclosed in U.S. Pat. No. 7,216,739 (previously incorporated herein by reference) is shown in connection with a handle  612  of a power tool  610 . The muffler assembly  600  includes a tube member  602  having an upper flange  604  that is configured to be slidably inserted into an exhaust passage  616  provided in the handle  612  of the power tool  610 . A tubular portion  606  extends downwardly from the flange  604 . The tubular portion  606  includes a number of apertures  608  distributed along its length. An oversized, downwardly opening receptacle  620  is disposed at the lower end of the tubular portion  606 . The receptacle  620  is also configured to be slidably insertable into the exhaust passage  616 , which is adjacent the inlet passage  614 . A flexible filter panel  622  is generally wrapped about the tubular portion  606  of the tube member  602 , and a diffuser panel  630  is inserted into the receptacle  620 . 
         [0026]    The upper flange  604  at the upper end of the tube member  602  and the receptacle  620  at the lower end of the tube member  602  are preferably configured to approximately conform to the shape of the exhaust passage  616 , such that the tube member  602  slides smoothly into the exhaust passage  616  and is maintained in a desired position therein. The tubular portion  606 , which is smaller in the transverse dimension than the upper flange  604  and receptacle  620 , is thereby positioned generally away from the walls of the exhaust passage  616 , providing a space for exhaust airflow and for the filter panel  622 . 
         [0027]    The tube member  602  is formed integrally from a rigid or semi-rigid polymeric material, although other suitable materials may be used, including, for example, relatively soft metals, composite materials, or the like. 
         [0028]    The flexible, sound-dampening and/or air-filtering panel  622  may be formed from any suitable porous filter material, including, for example, felt, gauze, foam, fiber, synthetics, etc. The filter panel  622  is selected of a density and composition sufficient to dampen noise in the exhaust flow, while also being sufficiently porous that the exhaust air can pass therethrough without unduly increasing backpressure in the power tool  610  during use. The filter panel  622  is disposed about the tubular portion  606  of the tube member  602 , between the upper flange  604  and the receptacle  620 . 
         [0029]    The filter panel  622  is between about one-eighth inch and about one-half inch in thickness and is flexible, such that the panel  622  may be conveniently wrapped around the tubular portion  606  and does not extend significantly beyond the upper flange  604 . The panel  622  maybe attached to the tubular portion  606  in any convenient manner for example, by selective application of an adhesive, a latching mechanism (not shown) disposed on the panel  622  (such as a hook-and-loop material), or a separate strap, string, wire, or tape (not shown) that wraps around the panel  622 . Alternatively, the panel  622  may be formed having a generally C-shaped cross section, and having sufficient stiffness to retain itself on the tube member  602 . It will be appreciated that the panel  622  may alternatively be wrapped about the tubular portion  606  without fastening and inserted into the exhaust passage  616 , such that the exhaust passage  616  cooperatively retains the panel  622  in the desired position. 
         [0030]    The diffuser panel  630  is configured to be slidably inserted into the receptacle  620 , the diffuser panel  630  being made from a relatively porous material such as a spacer fabric or similar porous material. The diffuser panel  630  provides additional sound dampening just prior to the exhaust air exiting the exhaust passage  616 . 
         [0031]    The tubular portion  606  of the tube member  602  includes a blocking panel (shown in hidden lines and not specifically identified) disposed between the upper and lower ends of the tube member  602 . 
         [0032]    The muffler assembly  600  is inserted into the exhaust passage  616  of the handle  612 , and an end cap  624  having one or more apertures  626  is secured over the exhaust passage  616  exit, to releasably secure the muffler assembly  600  therein. The end cap  624  may be attached by any suitable mechanism. The end cap  624  also includes an aperture  627  disposed over the inlet passage  614  opening to accommodate a coupling to a compressed air source (not shown). 
         [0033]    The muffler assembly  600  receives at least most of the exhaust air from the power tool  610 , which is directed into the tubular portion  606  of the tube member  602  by the upper flange  604 . The blocking panel redirects some or all of the entering exhaust air laterally through the apertures  608  above the blocking panel in the tubular portion  606  and through the filter panel  622 . The receptacle  620 , cooperatively with the exhaust passage  616 , then redirects the exhaust air through the apertures  608  below the blocking panel back into the tubular portion  606 . The exhaust air then passes through the diffuser panel  630  and exits the handle  612  through the apertures  626  in the end cap  624 . 
         [0034]    Turning now to  FIGS. 1-7 , the present disclosure provides a muffler assembly including some features similar to those of muffler assembly  600  ( FIG. 8 ), except that the muffler assembly of the present disclosure is configured to substantially changing the air flow through the muffler, thereby significantly improving tool performance. The muffler assembly of the present disclosure, similarly as detailed above with respect to muffler assembly  600  ( FIG. 8 ), is configured for use with a power tool  610 . For purposes of brevity, components and features of the muffler assembly of the present disclosure that are similar to that of muffler assembly  600  ( FIG. 8 ), e.g., filter panel  622 , diffuser panel  630 , and end cap  624 , are only summarily described hereinbelow or omitted entirely. 
         [0035]    The muffler assembly of the present disclosure includes a muffler tube member  102  defining an upper end and a lower end and having an upper segment  101 , a lower segment  103  extending coaxially in a downward direction from the upper segment  101 , and a receptacle  120  disposed at the lower end of the lower segment  103 . The upper segment  101  is relatively smaller in diameter than the lower segment  103 . In particular, the inside diameter of the upper segment  101  is smaller than the inside diameter of the lower segment  103 , and the outside diameter of the upper segment  101  is smaller than the outside diameter of the lower segment  103 . 
         [0036]    An integral (or otherwise engaged) cap  104  extends upwardly from the upper end of the upper segment  101 , closing the upper end of the tube member  102 . Therefore, unlike the tube member  602  of muffler assembly  600  (see  FIG. 8 ), the tube member  102  is closed at the upper end thereof such that exhaust air must flow around (not through) the top of the tube member  102 . To facilitate flow around the top of the tube member  102 , at least a portion of the cap  104  is tapered, e.g., frustoconical, transitioning to a larger diameter in the flow direction, i.e., in an upper-to-lower direction. Other tapered configurations are also contemplated. At the end of the cap  104 , adjacent the upper segment  101 , the cap  104  is larger in diameter than the upper segment  101 . 
         [0037]    The upper segment  101  includes a vented portion defined by a plurality of elongate circumferential (or partially-circumferential) apertures or vents  108 . The vented portion of the upper segment  101  may extend for less than half the total length of the upper segment  101 , e.g., about one-third the length of the upper segment  101 , and may be disposed at the upper end of the upper segment  101 , i.e., adjacent the cap  104 . The remaining portion of the upper segment  101 , i.e., the lower portion thereof adjacent the lower segment  103 , does not include any vents  108 , i.e., it defines a continuous cylindrical-shaped surface that prevents exhaust from passing therethrough. 
         [0038]    Similarly, the lower segment  103  includes a vented portion defined by a plurality of elongate circumferential (or partially-circumferential) apertures or vents  109 . The vented portion of the lower segment  103  may extend for about half the length of the lower segment  103 , and may be disposed at the upper end of the lower segment  103 , e.g., adjacent the upper segment  101 . The remaining portion of the lower segment  103 , i.e., the lower portion thereof adjacent the receptacle  120 , does not include any vents  109 , i.e., it defines a continuous cylindrical-shaped surface that prevents exhaust from passing therethrough. 
         [0039]    The receptacle  120  is similar to the receptacle  620  ( FIG. 8 ), and extends downwardly from the lower segment  103 . Therefore, the tube member  102  encloses a volume closed at the lower end and defined by the interior of the upper segment  101 , the lower segment  103 , and the receptacle  120 . As each element  101 ,  103 ,  120  defining successively larger cross-sectional areas, the volume increases in cross-sectional area in a downward, i.e., upper-to-lower, direction. The volume may also be free from blocking panels such as those detailed above with respect to the tube member  602  ( FIG. 8 ). 
         [0040]    The tube member  102  further comprises a plurality of external longitudinal elongate stand-offs or flanges  110 ,  112  that extend longitudinally from the upper end of the upper segment  101  downwardly to the receptacle  120  at the bottom end of the lower segment  103 . The flanges  110 ,  112  may define a radial dimension that tapers in the lower-to-upper direction such that the flanges  110 ,  112  extend from the tube member  102  a greater radial distance adjacent the lower end of the tube member  102  as compared to the upper end thereof Alternatively, flanges  110 ,  112  may each define a uniform radial dimension along its length. 
         [0041]    The tube member  102  is configured to receive the flexible filter panel  622  ( FIG. 1 ), similarly as described with respect to  FIG. 8 . For example, the filter panel  622  is wrapped about the upper and lower segments  101 ,  103  of the tube member  102 , and may be retained thereon by any convenient mechanism, e.g., an adhesive, latching mechanism (such as a hook-and-loop material), tie wrap, string, wire, or tape that wraps around the panel  622 . The panel  622  may also be formed having a generally C-shaped cross-section from a material having sufficient stiffness to retain itself on the tube member  102 . 
         [0042]    As can be appreciated, the flanges  110 ,  112  on tube member  102  cause the filter panel  622  to remain spaced apart from the tube member  102 , providing channels that define passageways for air between the tube member  102  and the filter panel  622 . 
         [0043]    The receptacle  120  is sized to fit into the tool exhaust passage  616  and to receive the diffuser panel  630 , as discussed above (see  FIG. 8 ). 
         [0044]    With continued reference to  FIGS. 1-7 , and to  FIG. 1  in particular, the exhaust flow path created via the configuration of the muffler assembly of the present disclosure, detailed above, will now be described. Initially, exhaust air exits the motor (not shown) of the power tool  610  and enters the exhaust passage  616 , where it encounters the closed upper end (as defined by cap  104 ) of the tube member  102 . As such, the air flows around the cap  104  and downwardly about the exterior of the tube member  102 , with at least a portion of the air flowing into the channels (created via flanges  110 ,  112 ) defined between the filter panel  622  and the upper segment  101 . A portion of the air enters the vents  108  of upper segment  101  near the upper end of the upper segment  101 , while another portion continues downwardly about the unvented cylindrical surface of the upper segment  101 . The air flow then encounters the larger-diameter lower segment  103 , where the inner flow (through the tube member  102 ) and outer flow (about the tube member  102 ) can communicate through the vents  109  defined through the lower segment  103 . The channel defined between the tube member  102  and the filter panel  622  is substantially closed at the bottom due to the positioning of receptacle  120 , such that most of the air will flow into the vents  109 . The air then flows through the diffuser panel  630  in the receptacle  120  and exits the power tool  610  out through the end cap  624 . 
         [0045]    From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the same. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.