Patent Publication Number: US-2007095606-A1

Title: Internal combustion engine exhaust line muffler

Description:
RELATED U.S. APPLICATIONS  
      Not applicable.  
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      Not applicable.  
     REFERENCE TO MICROFICHE APPENDIX  
      Not applicable.  
     FIELD OF THE INVENTION  
      The invention relates to an internal combustion engine exhaust line muffler.  
     BACKGROUND OF THE INVENTION  
      This invention relates to the field of the car industry and more particularly to that of the manufacture of the material an internal combustion engine exhaust line includes and which is designed capable of reducing the noise emissions resulting from the operation of such an engine.  
      In order to reduce such noise emissions, such an exhaust line includes at least one muffler which is, usually, in the form of a casing including, internally and in the direction of the exhaust gas flow, an intake pipe for these gases connected to the engine as well as at least one evacuation pipe for these gases emerging into the atmosphere.  
      When the engine is operating, the unit comprised of this engine and its exhaust line has a total noise formed, at least partly, by blowing noise and radiant noise.  
      In this respect, it should be noted that, when the engine operates at low speed, the blowing noise is predominant in the total noise. As the speed of this engine increases, there is an increase in radiant noise which, from a determined engine speed, becomes in turn predominant in the total noise.  
      When the acoustic performances of a vehicle have to be improved, it is already known to implement means arranged to ensure a reduction in radiant noise. The implementation of these means has however a number of drawbacks consisting, in particular, of an increase in exhaust line gas counter-pressure inducing a reduction of the performances of the engine.  
      There are also known means arranged to ensure a reduction of the blowing noise. The implementation of these means however occurs to the detriment of the treatment of radiant noise.  
     BRIEF SUMMARY OF THE INVENTION  
      This invention pretends to be capable of coping with the drawbacks of the devices of the state of the art.  
      To this end, this invention relates to an internal combustion engine exhaust line muffler including a casing as well as, extending inside said casing, in the exhaust gas flow direction, from the upstream portion and towards the downstream portion of this casing, on the one hand, an exhaust gas intake pipe emerging inside said casing and, on the other hand, an exhaust gas evacuation pipe emerging into the atmosphere and comprising an upstream end located inside said casing. The muffler comprises, inside said casing, on the one hand, means arranged to prevent, at least below a determined engine speed, penetration of exhaust gases into said evacuation pipe, through its upstream end and, on the other hand, an evacuation pipe portion provided with at least one perforation for penetration, into said evacuation pipe, of the exhaust gases from the intake pipe.  
      According to another feature of the invention, the evacuation pipe portion provided with at least one perforation includes a plurality of perforations distributed, preferably regularly, at the periphery of this evacuation pipe.  
      Still another feature relates to the fact that the perforated evacuation pipe portion extends substantially along an axis, while the perforation or perforations are arranged, in this evacuation pipe portion, according to an axis extending either in a plane forming an angle with the axis of the evacuation pipe or in a radial direction with respect to the axis of this evacuation pipe.  
      According to an additional feature, the exhaust gas intake pipe emerges inside said casing through at least one opening provided for in the downstream portion of this intake pipe, preferably in the vicinity or at the level of a downstream end located inside this casing and which this intake pipe includes.  
      According to another feature of the invention, the evacuation pipe includes, at least at the level of its portion provided with at least one perforation, means arranged to define at least one channel, on the one hand, emerging in the internal volume of the casing and, on the other hand, communicating with the perforation or perforations of the evacuation pipe portion. This channel is designed so as to establish a counter-current gas exhaust flow with respect to the path of these gases in the evacuation pipe, this in order to extend the path of these gases in the casing.  
      According to an additional feature, the means arranged to prevent, irrespective of the engine speed, a penetration of exhaust gases into the evacuation pipe are formed by means for obturating this evacuation pipe, more particularly the upstream end of the latter.  
      Still another feature relates to the fact that the casing is subdivided by at-least one tight dished plate defining an upstream compartment and a downstream compartment in which the intake pipe emerges, while said evacuation pipe, on the one hand, extends through said downstream compartment and, on the other hand, passes through said tight dished plate so that the upstream end of this evacuation pipe is located inside said upstream compartment. This tight dished plate forms said means arranged to prevent, irrespective of the engine speed, penetration of the exhaust gases into the evacuation pipe through its upstream end.  
      According to an additional feature, the means arranged to prevent, below said determined engine speed, penetration of the exhaust gases into the evacuation pipe through its upstream end are formed by a valve associated with this upstream end and arranged, on the one hand, to remain closed below said determined engine speed and, on the other hand, to be opened above this engine speed, in order to authorize the flowing of the exhaust gases into the evacuation pipe through its upstream end.  
      Another feature consists in that the casing is subdivided by at least one dished plate defining an upstream compartment and a downstream compartment in which the intake pipe emerges, while said evacuation pipe, on the one hand, extends through said downstream compartment and, on the other hand, passes through said dished plate, so that the upstream end of this evacuation pipe emerges inside said upstream compartment. This dished plate is provided with a valve arranged, on the one hand, to remain closed below a determined engine speed and, on the other hand, to be opened above this engine speed, in order to authorize the flowing of the exhaust gases from the downstream compartment into the upstream comportment, this valve and this dished plate forming said means arranged to prevent, below said determined engine speed, penetration of the exhaust gases into the evacuation pipe through its upstream end.  
      The advantages of this invention consist in that this muffler allows to remarkably reduce, over the full range of operation speeds of the engine, the blowing noise as well as the radiant noise without the reduction of either one of these noises being to the detriment either of the other one or of the performances of the engine, or of the overall acoustic performance of the vehicle. This results into a substantial improvement of the acoustic comfort of the exhaust line equipped with a muffler according to the invention. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
      The invention is set forth more in detail in the following description referring to embodiments given by way of examples and shown in the figures of the attached drawings.  
       FIGS. 1 and 2  are schematic views of a muffler corresponding to a first type of embodiment of the invention.  
       FIG. 3  is a schematic view similar to  FIGS. 1 and 2  and corresponds to an advantageous evolution of the embodiments shown in these two figures.  
       FIGS. 4 and 5  are schematic views similar to FIGS.  1  to  3  and correspond to a second type of embodiment of the muffler according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      As evoked above, this invention relates to the field of the car industry and more particularly to that of the manufacture of material designed capable of reducing the noise emissions of an internal combustion engine.  
      As known per se, such an engine is completed, at its outlet, with an exhaust line  1  arranged to ensure the evacuation of the exhaust gases produced by the combustion of an air-fuel mixture within this engine.  
      Such an exhaust line  1  usually includes at least one muffler  2  aimed at reducing the noise emissions of the exhaust system and at improving the acoustic performances of the vehicle.  
      Such a muffler  2  is in the form of a case  3 , located on the flow path of the exhaust gases from the engine, and connected to the latter through an exhaust pipe  4 .  
      This muffler  2  includes a casing  5  having an upstream portion  6  as well as a downstream portion  7 , with respect to the flow direction of the exhaust gases through this casing  5 .  
      Said muffler  2  also includes at least one exhaust gas intake pipe  8  as well as at least one evacuation pipe  9  for these gases, these pipes  8 ,  9  extending inside said casing  5 , from the upstream portion  6  towards the downstream portion  7  of this casing  5 , this in the flow direction of these gases.  
      As regards said gas intake tube  8 , it can, as the case may be, be formed by a portion of said exhaust pipe  4  connected to the engine or also connected to this pipe  4 , preferably outside said muffler  2 . This intake pipe  8  emerges inside the casing  5  of the muffler  2 , through at least one opening  10 .  
      As regards said evacuation pipe  9 , it includes an upstream end  11  located inside said casing  5  and extends through the wall of the downstream portion  7  of said case  3 , so as to emerge, outside this case  3  and through a nozzle  12 , into the atmosphere.  
      According to the invention, the muffler  2  includes, inside said casing  5 , on the one hand, means  13  arranged to prevent, at least below a determined engine speed, a penetration of exhaust gases inside the evacuation pipe  9 , this through the upstream end  11  of the latter  9 .  
      On the other hand, this muffler  2  includes, also inside said casing  5 , a portion  14  of evacuation pipe  9  provided with at least one perforation  15  for the penetration, inside this evacuation pipe  9 , of the exhaust gases from the intake pipe  8 .  
      In this respect, one should note that, according to a first embodiment, not shown, this or these perforations  15  can be provided for in a portion  14  of the evacuation pipe  9  facing the intake pipe  8  or, to the contrary, at the rear of this evacuation pipe  9  with respect to said intake pipe  8 .  
      However and according to a preferred embodiment of the invention as can be seen in FIGS.  1  to  5 , this portion  14  of evacuation pipe  9  includes a plurality of perforations  15  distributed, preferably regularly, at the periphery of this evacuation pipe  9 .  
      It should be noted that said evacuation pipe  9  extends (at least at the level of its portion  14  provided with perforations  15 ) substantially along an axis  16  and has a cross-section that can be polygonal, in particular rectangular or square, but which is preferably circular.  
      Also and according to another feature of the invention, the perforation or perforations  15  are provided for, in the portion  14  of this evacuation pipe  9 , according to an axis extending in a plane forming an angle with the axis  16  of the evacuation pipe  9 . Such an orientation of the axis of the perforation or perforations  15  can contribute to facilitating the penetration and the flow of exhaust gases inside the evacuation pipe  9 .  
      In this respect, it should be noted that a preferred embodiment consists in that this or these perforations  15  are provided for according to an axis extending in a radial direction with respect to the axis  16  of this evacuation pipe  9 .  
      In fact, the muffler  2  according to the invention includes a portion  14  of evacuating pipe  9  preferably provided with a plurality of perforations  15 .  
      According to an additional feature, the perforations  15  defined at the level of said portion  14  of the evacuation pipe  9  are arranged according to at least one line of perforations  15 , this or these lines being provided for radially and/or axially with respect to the axis  16  of the evacuation pipe  9 .  
      According to another feature of the invention, the muffler  2  also includes means arranged to extend the path of the exhaust gases inside the casing  5 , this in order to attenuate, here too, the total noise of the vehicle.  
      To this end and as can be seen in the figures of the attached drawings, the portion  14  of evacuation pipe  9  provided with at least one perforation  15  is located in the upstream portion  17  of this evacuation pipe  9 , preferably near the upstream end  11  of the latter  9 .  
      According to another feature of the invention, the exhaust gas intake pipe  8  emerges inside said casing  5  through at least one opening  10 .  
      In this respect, one should note that such an opening  10  can be provided for in the downstream portion  18  of this intake pipe  8 , namely near a downstream end  19 , located inside this casing  5 , and which this intake pipe  8  includes. In such a case, such an opening  10  can consist of a perforation of said intake pipe  8 .  
      However and according to a preferred embodiment visible in the attached figures, such an opening  10  is provided for at the level of this downstream end  19  of the intake pipe  8 .  
      Such embodiments allow, in combination with a portion  14  located in the upstream portion  17  of the evacuation pipe  9 , to extend the paths of the gases in the casing  5 .  
      According to an additional feature of the invention and as can be seen in  FIG. 3 , the evacuation pipe  9  includes, at least at the level of its portion  14  provided with at least one perforation  15 , means arranged to define at least one channel  20 .  
      Such a channel  20  is arranged to emerge in the inner volume of the casing  5  and to communicate with the perforation or perforations  15  of the portion  14  of evacuation pipe  9 . This channel  20  is designed so as to create at least one counter-current exhaust gas flow with respect to the path of these gases in the evacuation pipe  9 , this in order to extend the path of these gases in the casing  5 .  
      In this respect, it should be noted that the means arranged to define a channel  20  consist of a sleeve  21 , in particular a tubular and/or annular sleeve, arranged at least over the portion  14  of evacuation pipe  9  including at least one perforation  15 .  
      According to a preferred embodiment of the invention visible in  FIG. 3 , such a sleeve  21  extends substantially to the vicinity of the downstream end of the casing  5  of the muffler  2 .  
      In addition, it should be noted that, when one wishes to extend the path of the gases in the casing  5 , a particularly advantageous embodiment consists of a casing  5  inside which the intake pipe  8  (provided with at least one opening  10 , preferably provided for at the level of the downstream end  19  of this pipe  8 ) extends substantially to the vicinity of the downstream end of the casing  5 , while the evacuation pipe  9  (including a portion  14  provided with at least one perforation  15  and preferably located near the upstream end  11  of the evacuation pipe  9 ) extends substantially to the vicinity of the upstream end of the casing  5 .  
      According to another feature of the invention and as evoked above, the evacuation pipe  9  includes means  13  arranged to prevent, at least below a determined engine speed, penetration of the exhaust gases inside this evacuation pipe  9 , this through its upstream end  11 .  
      In FIGS.  1  to  3 , a first type of muffler  2  has been shown for which the means  13  arranged to prevent a penetration of the exhaust gases into the evacuation pipe  9  through its upstream end  11  are so defined as to prevent, irrespective of the engine speed, such a penetration of these gases.  
      According to a first embodiment shown in  FIG. 1 , the means  13  arranged to prevent, irrespective of the engine speed, penetration of the exhaust gases into the evacuation pipe  9 , consist of means  22  for obturating this evacuation pipe  9 .  
      Such obturating means  22  are, more particularly, capable of ensuring an obturation of the upstream end  11  of this evacuation pipe  9 . Alternatively, such obturating means  22  can be designed capable of ensuring an obturation of this evacuation pipe  9  between the upstream end  11  of the latter  9  and the portion  14  provided with at least one perforation  15 .  
      According to another embodiment shown in  FIG. 2 , the casing  5  of said mufflers  2  includes, internally, at least one tight dished plate  23  designed capable of subdividing said casing  5  and of defining, in the latter  5 , an upstream compartment  24  and a downstream compartment  25  in which the intake pipe  8  emerges.  
      In this embodiment, the evacuation pipe  9 , on the one hand, extends through said downstream compartment  25  and, on the other hand, passes through said tight dished plate  23  so that the upstream end  11  of this evacuation pipe  9  is located inside said upstream compartment  24 , isolated from the downstream compartment  25  by said tight dished plate  23 .  
      This results in that the exhaust gases, proceeding from said intake pipe  8 , penetrate into the evacuation pipe  9 , while flowing only through the perforation or perforations  15  which said portion  14  of this evacuation pipe  9  includes.  
      Thus, said tight dished plate  23  forms said means  13  arranged to prevent, irrespective of the engine speed, penetration of the exhaust gases into the evacuation pipe  9  through its upstream end  11 .  
      In  FIGS. 4 and 5 , a second type of muffler  2  has been shown for which the means  13  arranged to prevent penetration of the exhaust gases into the evacuation pipe  9  through its upstream end  11  are defined so as to prevent, below a determined engine speed, such a penetration of these gases.  
      As can be seen in  FIG. 4 , the means  13  (arranged to prevent, below said determined engine speed, penetration of the exhaust gases into the evacuation pipe  9  through its upstream end  11 ) consist of a valve  26  associated with this upstream end  11 . This valve  26  is arranged, on the one hand, to remain closed below said determined engine speed (shown in discontinuous lines) in order to prevent the flow of the gases through the upstream end  11  of the evacuation pipe  9  and, on the other hand, to be opened above this engine speed (shown in full lines) in order to authorize the flow of the exhaust gases into the evacuation pipe  9  through its upstream end  11 .  
      According to another embodiment shown in  FIG. 5 , the casing  5  is subdivided by at least one dished plate  27  delimiting an upstream compartment  24  and a downstream compartment  25  in which the intake pipe  8  emerges.  
      In this embodiment, said evacuation pipe  9 , on the one hand, extends through said downstream compartment  25  and, on the other hand, passes through said dished plate  27  so that the upstream end  11  of this evacuation pipe  9  emerges inside said upstream compartment  24 .  
      This dished plate  27  is provided with a valve  26  arranged, on the one hand, to remain closed (shown in discontinuous lines) below a given engine speed (here too, in order to prevent the gas from flowing through the upstream end  11  of the evacuation pipe  9 ) and, on the other hand, to be opened (shown in full lines) above this engine speed, in order to authorize the exhaust gases to flow from the downstream compartment  25  into the upstream compartment  24 , then into the evacuation pipe  9  through its upstream end  11 .  
      This valve  26  and this dished plate  27  then form said means  13  arranged to prevent, below said determined engine speed, penetration of the exhaust gases into the evacuation pipe  9  through its upstream end  11 .  
      According to another feature of the invention, the valve  26  provided, as the case may be, on the evacuation pipe  9  or the dished plate  27 , is an overpressure valve, in particular of a self-controlled type.  
      As regards said dished plate  27 , it is preferably of an exhaust gas tight type.  
      It should be noted that in the embodiments shown in  FIGS. 2 and 5 , the casing  5  is subdivided by a dished plate  23 ,  27 . In this respect, it should be noted that the portion  14  of the evacuation pipe  9  (provided with at least one perforation  15  for the penetration, into this tube  9 , of the exhaust gases proceeding from the intake pipe  8 ) is located downstream of the dished plate  23 ,  27  and in the downstream compartment  25  of the casing  5 .  
      In this respect, it should be noted that the muffler  2  according to the invention can also include, internally, at least one dished plate for ensuring the mounting of at least one (intake  8  and/or evacuation  9 ) pipe inside said casing  5 .  
      A particular embodiment can consist in that such a dished plate can be formed by the dished plate  23 ,  27  of the means  13  capable of preventing the penetration of the exhaust gases into the evacuation pipe  9  through its upstream end  11 .  
      As regards the embodiments shown in  FIGS. 4 and 5 , they can, in the same way as the embodiments shown in  FIGS. 1 and 2 , receive means arranged to extend the path of these gases in casing  5  (channel  20 , sleeve  21 , implanting of perforations  15  and/or the opening  10 ).