Patent Publication Number: US-11655741-B2

Title: Muffler for engine

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to Japanese Patent Application No. 2018-097581 filed May 22, 2018, which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a muffler for an engine intended to reduce the radiated sound from a muffler body (shell). 
     BACKGROUND 
     As a muffler (silencer) used in the engine of a vehicle such as an automobile, a press muffler obtained by press-forming a metal plate is widely used. The press muffler is generally formed by pressing a thin metal plate of about 1 mm to 1.5 mm. In this type of muffler, the wall thickness of the shell is increased or the shell is formed into a two-layer structure in order to suppress the increase of the radiated sound from the shell. 
     For example, U.S. Pat. No. 7,913,811B describes a single-shell press muffler having a structure in which a single-layer shell (muffler body) and a baffle plate are joined. U.S. Pat. No. 7,926,615B describes a double-shell press muffler having a structure in which a two-layer shell and a baffle plate are joined. 
     SUMMARY 
     Incidentally, although the single-shell press muffler described in U.S. Pat. No. 7,913,811B is light and low-cost when the muffler size is increased and the muffler shape is flattened, there are problems of radiated sound and inner pressure strength. Thus, such single-shell press muffler does not work as a muffler. 
     The double-shell press muffler described in U.S. Pat. No. 7,926,615B has advantages in terms of strength and effect of low radiated sound due to its frictional damping effect. However, it has disadvantages in terms of cost and weight. 
     An object of the present invention is to provide a muffler for an engine wherein the muffler can reduce the muffler radiated sound, improve the strength, and reduce the weight. 
     According to the first aspect of the present invention, a muffler for an engine includes a muffler body, at least one partition wall, and at least one reinforcing plate. The muffler body has an inner space formed by a shell. The partition wall includes a flange portion that is in tight contact with an inner surface of the shell, and divides the inner space of the muffler body into a plurality of chambers. The reinforcing plate is welded on an outer surface of the shell at a position facing the flange portion of the partition wall. 
     According to the above configuration, the muffler for the engine can reduce the muffler radiated sound, improve the strength, and reduce the weight, by welding the reinforcing plate on the outer surface of the shell at a position facing the flange portion of the partition wall. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a plane view of a muffler for an engine according to an embodiment; 
         FIG.  2    is an exploded perspective view of a muffler body used in the muffler for the engine; 
         FIG.  3    is a cross-sectional view taken along the line in  FIG.  1   ; 
         FIG.  4    is a cross-sectional view taken along the IV-IV line in  FIG.  3   ; 
         FIG.  5    is a perspective view of a partition wall used in the muffler for the engine; 
         FIG.  6    is a partial perspective view showing a three-layer bonding structure of a flange portion of the partition wall, a shell and a reinforcing plate, partially in a cross section; and 
         FIG.  7    is an explanatory view showing a deformation-suppressing-state after the three-layer bonding of the flange portion of the partition wall, the shell, and the reinforcing plate. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments will be described below with reference to the drawings. 
       FIG.  1    is a plane view of a muffler for an engine according to an embodiment;  FIG.  2    is an exploded perspective view of a muffler body used in the same muffler;  FIG.  3    is a cross-sectional view taken along the line in  FIG.  1   ;  FIG.  4    is a cross-sectional view taken along the IV-IV line in  FIG.  3   ;  FIG.  5    is a perspective view of a partition wall used in the same muffler;  FIG.  6    is a partial perspective view showing a three-layer bonding structure of a flange portion of the same partition wall, a shell, and a reinforcing plate, partially in cross-section;  FIG.  7    is an explanatory view showing a deformation-suppressing-state after the three-layer bonding of the flange portion of the partition wall, the shell, and the reinforcing plate. 
     As shown in  FIGS.  1 ,  3 , and  4   , a muffler  1  for an engine is a press muffler obtained by press-forming a metal plate and attached to an exhaust pipe of the engine not shown. The muffler  1  for the engine comprises a muffler body  10 , an upstream exhaust pipe  20  connected to an end side in the longitudinal direction LG of the muffler body  10 , and a downstream exhaust pipe  30  connected to the other end side in the longitudinal direction LG. 
     As shown in  FIGS.  2  and  3   , opposing peripheral edges  11   s  and  12   s  of two shells  11  and  12  are joined by welding or caulking together. Thereby the muffler body  10  is formed in a bag shape which is flat other than the opposing peripheral edges  11   s  and  12   s  of substantially long elliptical cross section having an inner space K. The two shells  11  and  12  are made, for example, by pressing a metal sheet having a thickness of 0.8 mm. The shell  11  is the upper half-cylinder plate and the shell  12  is the lower half-cylinder plate, which respectively correspond to the muffler body  10  divided in half. The inner space K of the muffler body  10  is divided into a plurality of expansion chambers  17 ,  18  and  19  by a plurality of baffle plates  15  each having a flange portion  15   b  in tight contact with an inner surface  11   a / 12   a  of each shell  11 / 12 . 
     Further, as shown in  FIGS.  3  and  4   , a tip  20   a  of the upstream exhaust pipe  20  penetrates an endplate portion  13  at an end side and communicates with the expansion chamber  19  at the other end side, passing through through-holes  15   f  of the baffle plates  15 . A tip  30   a  of the downstream exhaust pipe  30  penetrates an endplate portion  14  at the other end side and communicates with the expansion chamber  17  at the end side, passing through through-holes  15   e  of the baffle plates  15 . Further, the adjacent expansion chambers  17 ,  18 , and  19  communicate with each other through communication pipes  40  and  41  passing through the baffle plates  15 . Thus, the exhaust gas G introduced from the upstream exhaust pipe  20  exits from the downstream exhaust pipe  30  in the arrow&#39;s route in the drawing through the communication pipes  40  and  41 . The sound is reduced while the exhaust gas G passing through the respective chambers  17 ,  18  and  19 . 
     As shown in  FIG.  5   , the baffle plate  15  has a plate body  15   a  perpendicular to the inner surface  11   a  of the shell  11 , and a short cylindrical flange portion  15   b  extending along the inner surface  11   a  of the shell  11  from the periphery of the plate body  15   a  in the axial direction (the longitudinal direction LG of the muffler body  10 ). A reinforcing plate  50  is welded on an outer surface  11   b / 12   b  of each shell  11 / 12  at a position facing the position where the flange portion  15   b  of the baffle plate  15  is provided. The reinforcing plate  50  is, for example, a rectangular metal plate having a thickness of 1 mm, and the thickness of the baffle plate  15  is, for example, 1.2 mm. 
     Furthermore, as shown in  FIGS.  1  to  3   , in each shell  11 / 12 , recessed grooves  11   c / 12   c  in each pair are formed in parallel along a direction perpendicular to the longitudinal direction LG of the muffler body  10 . The recessed grooves  11   c / 12   c  are recessed in a U-shape from the outer surface  11   b / 12   b  side to the inner surface  11   a / 12   a  side. In the longitudinal direction LG of the muffler body  10 , the recessed grooves  11   c / 12   c  in each pair are located on both end sides in the axial direction of the flange portion  15   b  of each baffle plate  15 . The rectangular-shaped reinforcing plate  50  having a width equal to or broader than the width of the flange portion  15   b  of the baffle plate  15 , is joined to each outer surface  11   b / 12   b  between the recessed grooves  11   c / 12   c  in each pair, by two types of welding, which are spot welding and plug welding. In the present embodiment, the reinforcing plate  50  is joined so as to cover all the positions facing the flange portion  15   b  of the baffle plate  15 . 
     The bonding procedure by welding the three-layer bonding structure of the flange portion  15   b  of the baffle plate  15 , the shell  11 / 12 , and the reinforcing plate  50 , shown in  FIG.  6   , will be described in detail. First, as shown in  FIG.  2   , a plurality of long holes  51  is formed at equal intervals in the widthwise center of the rectangular-shaped reinforcing plate  50  along its longitudinal direction. Further, a plurality of long holes  11   d / 12   d  is formed at equal intervals in the center of each pair of the recessed grooves  11   c / 12   c  of the shell  11 / 12 , so as to face the respective long holes  51  of the reinforcing plate  50 . 
     Then, the rectangular-shaped reinforcing plate  50  is piled and attached on the outer surface  11   b / 12   b  of the shell  11 / 12 , between the recessed grooves  11   c ,  12   c  in each pair, in a state where the respective long holes  11   d / 12   d  of the shell  11 / 12  and the respective long holes  51  of the reinforcing plate  50  are aligned. Then, both sides of the widthwise center of the reinforcing plate  50  with the formed long holes  51  are respectively joined by spot welding to the shell  11 / 12  (this welded portion is indicated by reference numeral S) at equal intervals at a plurality of places (in this embodiment, one side five places, a total of 10 places) along the longitudinal direction, in advance. 
     Next, the rectangular-shaped reinforcing plate  50  is joined to the flange portion  15   b  of the baffle plate  15  across the shell  11 / 12  via the respective long holes  51 ,  11   d / 12   d  by plug welding (this welded portion is indicated by reference numeral P in the drawing) at equal intervals at a plurality of places (five places in this embodiment). Thus, the three-layer bonding structure of the flange portion  15   b  of the baffle plate  15 , the shell  11 / 12 , and the reinforcing plate  50  is formed as shown in  FIG.  6   . 
     In the muffler body  10  of the muffler  1  for the engine, having such a configuration, when the inner pressure load M of the mechanical load caused by gas pressure or thermal load or vibration input acts on the shells  11  and  12  being a press muffler, the tension N is applied to the baffle plate  15  by the reaction, as shown in  FIG.  7   . However, it is possible to suppress the deformation near the welded portion P of the flange portion  15   b  of the baffle plate  15  and the shell  11 / 12  by the three-layer bonding structure of the flange portion  15   b  of the baffle plate  15 , the shell  11 / 12  and the reinforcing plate  50 , as shown in  FIG.  6   . Furthermore, it is possible to reliably prevent cracking and breakage of the flange portion  15   b  of the baffle plate  15  and the shell  11 / 12  from the welded portion P because the concentration of strain is dispersed and mitigated. As a result, it is possible to improve the strength of the shell  11 / 12  against gas pressure and thermal load and vibration input. At the same time, it is possible to reduce the weight of the muffler body  10  by reducing the thickness of the single layer portion of the shell  11 / 12 . 
     Further, the jointed portion of the shell  11 / 12  and the flange portion  15   b  of the baffle plate  15 , serving as a node of the vibration mode of the muffler body  10 , is held by a rectangular-shaped reinforcing plate  50  having a width wider than the flange portion  15   b  not only the point portion of the welded portion P. Therefore, it is possible to reduce the muffler radiated sound because the vibration amplitude of the shells  11 / 12  is reduced. That is, as compared with the things to achieve the damping effect due to two-layering or the stiffness increase due to the thickness increase of the shell  11 / 12 , it is possible to reduce radiated sound efficiently through vibration amplitude suppressing effect in the shell  11 / 12  caused by the reinforcing plate  50 , without increasing weight. 
     Furthermore, as shown in  FIG.  2   , it is possible to reduce the cost through reduced number of parts as the muffler body  10  having an inner space K is formed by joining the opposing peripheral edges  11   s  and  12   s  of the upper and lower two shells  11  and  12  by welding or caulking together. 
     In the above embodiment, the number of baffle plates (partition wall) is two. However, the number of the baffle plates and the number of the chambers partitioned by the baffle plates are not limited to this, and the number of the reinforcing plates is not limited to two. Furthermore, although the shell and the reinforcing plate are welded in advance by spot welding, they may be welded by TIG welding or MIG welding or the like. 
     Thus, the present invention can include various embodiments and the like not described herein. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention regarding the following claims that are reasonable from the above description.