Patent Publication Number: US-11377991-B2

Title: Muffler device

Description:
TECHNICAL FIELD 
     The present invention relates to a muffler device, and particularly relates to a muffler device that is applied to an engine of a portable generator. 
     BACKGROUND ART 
     There has been conventionally known a muffler device for silencing an engine. 
     As the muffler device like this, for example, there is conventionally disclosed a technology that includes outer plates, and a cylindrical outer shell that supports the respective outer plates, and reduces exhaust noise by reducing exhaust energy in a muffler (refer to Patent Literature 1, for example). 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] 
     Japanese Patent Laid-Open No. 2005-155551 
     SUMMARY OF INVENTION 
     Technical Problem 
     The above described conventional technology is a technology concerning a muffler device of an engine for a vehicle. However, there is known a generator that drives an engine and generates power by the driving force, and the aforementioned conventional technology cannot be directly applied as the muffler device of the generator like this. 
     In particular, a portable generator needs to be equipped with a catalyst device to purify NOx, and in addition, the portable generator is required to be lightweight and compact. 
     An aspect of the present invention is made in the light of the aforementioned point, and has an object to provide a lightweight and compact muffler device that can be installed in a limited space in an inside of a generator, and can ensure a sufficient capacity. 
     Solution to Problem 
     In order to attain the above described object, an aspect of the present invention is a muffler device of a portable generator, including a casing disposed vertically, wherein end covers provided on a top and a bottom of the casing are each formed in a substantially trapezoidal shape. 
     According to an aspect of the present invention, an inner capacity of the casing can be secured to be larger as compared with a case where the end covers are each formed into a planar shape, and rigidity can also be enhanced. As a result, the size of the muffler device can be made compact, and no extra component is required, so that reduction in manufacturing cost and reduction in weight can be achieved. Further, since the casing is disposed vertically, it becomes possible to install the casing even when the installation space is small in the inside of the housing of the generator, and it becomes possible to make the generator compact. 
     In the above described configuration, the end covers are formed of a top cover provided at an upper portion of the casing, and an undercover provided at a lower portion of the casing, and an inclined surface is formed on a top surface of the top cover, and an exhaust pipe and a tail pipe are connected to the inclined surface of the top cover. 
     According to the present invention, it becomes possible to concentrate the connection portions to the exhaust pipe and the tail pipe on the upper portion of the casing, and maintainability can be improved. 
     The above described configuration includes a catalyst device in an inside of the casing, wherein the catalyst device is disposed in a vertical direction. 
     According to an aspect of the present invention, by disposing the catalyst device in the vertical direction, carbon in the inside of the catalyst device can be made difficult to accumulate. 
     In the above described configuration, a diffuser pipe is disposed between a connection portion of the top cover to the exhaust pipe, and a placement position of the catalyst device, in the inside of the casing. 
     According to an aspect of the present invention, the diffuser pipe is disposed between the connection portion to the exhaust pipe, and the placement position of the catalyst device, and therefore, a space in which the exhaust gas flowing into the casing exists before entering the catalyst device can be secured to be wide. As a result, the high-temperature exhaust gas flowing into the casing from the exhaust pipe is cooled before flowing into the catalyst device, and it becomes possible to prevent the catalyst device from being deteriorated by the high-temperature exhaust gas. 
     In the above described configuration, the diffuser pipe extends over a substantially entire region in an up-down direction of the casing, and an arrester is disposed in a connection portion of the diffuser pipe to the tail pipe. 
     According to an aspect of the present invention, the arrester is disposed in the inside of the connection pipe of the diffuser pipe, and therefore, reduction in size can be achieved while the silencing function is kept. 
     The specification claims the benefit of priority of Japanese Patent Application No. 2017-243064 filed on Dec. 19, 2017, the entire contents of which are hereby incorporated by reference. 
     Advantageous Effects of Invention 
     According to an aspect of the present invention, as compared with the case where the end covers are each formed in a planar shape, the inner capacity of the casing can be secured to be larger, and rigidity can also be enhanced. As a result, the size of the muffler device can be made compact, and no extra component is required, so that reduction in manufacturing cost and reduction in weight can be achieved. Further, since the casing is disposed vertically, it becomes possible to install the casing even when the installation space is small in the inside of the housing of the generator, and the generator can be made compact. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view illustrating an embodiment of a generator to which a muffler device of the present invention is applied. 
         FIG. 2  is a front view of the muffler device of the present embodiment. 
         FIG. 3  is a sectional view in line A-A in  FIG. 2 . 
         FIG. 4  is a sectional view in line B-B in  FIG. 3 . 
         FIG. 5  is a sectional view in line C-C in  FIG. 4 . 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 
       FIG. 1  is a perspective view illustrating an external appearance of a portable generator to which a muffler device according to the present invention is applied. 
     As illustrated in  FIG. 1 , a generator  1  includes a housing  10  in a substantially rectangular parallelepiped shape, and an engine (not illustrated) and a muffler device  20  (refer to  FIG. 2 ) are housed in a lower part inside of the housing  10 . Power generation is enabled via an alternator by driving the engine. 
     Further, a control panel  13  in which power outlets  11 , operation buttons  12  and the like are disposed is fitted to one side surface of the housing  10 . 
     Further, a handle  15  is provided on a top surface of the housing  10 , and a plurality of legs  16  that support the housing  10  are attached to an undersurface of the housing  10 . 
     Next, the muffler device will be described. 
       FIG. 2  is a front view of the muffler device.  FIG. 3  is a sectional view in line A-A in  FIG. 2 .  FIG. 4  is a sectional view in line B-B in  FIG. 3 .  FIG. 5  is a sectional view in line C-C in  FIG. 4 . 
     As illustrated in  FIG. 2  to  FIG. 5 , the muffler device  20  includes a casing  21 , and the casing  21  is formed into an elliptical shape in plan view and has a flat shape in a front-rear direction. The casing  21  is formed, for example, by doubly winding and molding a plate-shaped member. In the present embodiment, the casing  21  is installed vertically. 
     Further, a top cover  22  that forms an end cover is attached to an upper portion of the casing  21 , and an undercover  23  forming an end cover is attached to a lower portion of the casing  21 . In the top cover  22 , a top surface includes an inclined surface  24  that inclines downward to a front. Further, the top cover  22  has a rear part formed in a curved surface shape, and is formed into a substantially trapezoidal shape in side view. 
     An exhaust hole  25  for connecting an exhaust pipe (not illustrated) is formed on one side of the inclined surface  24  of the casing  21 , and a tail pipe hole  26  for connecting a tail pipe  60  is formed in a substantially center of the inclined surface  24 , respectively. 
     In the present embodiment, by connecting the exhaust pipe to the inclined surface  24  of the casing  21 , it is possible to apply cooling air for the engine to the exhaust pipe, and it is possible to reduce a temperature of exhaust gas of the engine, which flows in the exhaust pipe. 
     The undercover  23  has a shape in which corner portions in the front-rear direction are formed into curved surface shapes, and a central portion swells downward, and is formed into a substantially trapezoidal shape in side view as a whole. An attaching flange  27  is formed on an undersurface of the undercover  23  to protrude downward. 
     Further, screw holes  28  are formed respectively in a periphery of the exhaust hole  25  and in a periphery of the tail pipe hole  26 . 
     A first partition wall  30  and a second partition wall  31  that are disposed with a predetermined space in an up-down direction are respectively provided in an inside of the casing  21 . The inside of the casing  21  is partitioned into an upper first chamber  32 , an intermediate second chamber  33 , and a lower third chamber  34  by the first partition wall  30  and the second partition wall  31 . The first chamber  32  communicates with the exhaust hole  25 . The second partition wall  31  is provided with a communication hole  35  that allows the second chamber  33  and the third chamber  34  to communicate with each other. 
     In the inside of the casing  21 , a catalyst device  40  that extends in a vertical direction to penetrate through the first partition wall  30  and the second partition wall  31  is provided. Pores  41  by punching that open to the first chamber  32  are formed in an upper portion of the catalyst device  40 . Pores  42  by punching that open to the second chamber  33  are formed in a lower portion of the catalyst device  40 . 
     By disposing the catalyst device  40  in the vertical direction in this way, it is possible to make it difficult for carbon inside of the catalyst device  40  to accumulate. 
     In the inside of the casing  21 , a diffuser pipe  50  that extends over a substantially entire region in the up-down direction by penetrating through the first partition wall  30  and the second partition wall  31  is provided. The diffuser pipe  50  is formed of an outer tube  51  and an inner tube  52 , and a large number of pores  53  formed by punching are formed in the inner tube  52 . The outer tube  51  and the inner tube  52  are integrally formed by welding or the like on upper sides and lower sides thereof. 
     A connection pipe  54  that is connected to the tail pipe hole  26  is connected to an upper end portion of the outer tube  51 , and an arrester  55  is disposed inside of the connection pipe  54 . 
     In the present embodiment, the diffuser pipe  50  is disposed between the exhaust hole  25  that is a connection portion of the exhaust pipe, and a placement position of the catalyst device  40 . Accordingly, high-temperature exhaust gas that flows into the first chamber  32  from the exhaust pipe is cooled before flowing into the catalyst device  40 , and it becomes possible to prevent the catalyst device  40  from being deteriorated by the high-temperature exhaust gas. 
     Further, since the arrester  55  is disposed in an inside of the connection pipe  54  of the diffuser pipe  50 , it becomes possible to achieve compactification while keeping a silencing function. 
     The muffler device  20  of the present embodiment is attached to the generator  1 , for example, by fixing the attaching flange  27  to a crankcase of the engine by screws, and fastening the exhaust pipe to the exhaust hole  25  by screws via the screw holes  28 . 
     It is possible to detach the muffler device  20  easily by only detaching the respective screws. As a result, maintenance of the muffler device  20  can be performed easily. 
     Next, an operation of the muffler device  20  configured in this way will be described. 
     Exhaust gas generated from the engine firstly flows into the first chamber  32  of the casing  21  via the exhaust hole  25  via the exhaust pipe. At this time, the exhaust gas can be caused to flow into the casing  21  in a state where a temperature of the exhaust gas is reduced by effectively using cooling air of the engine, by connecting the exhaust pipe to the inclined surface  24  of the top cover  22 . 
     The exhaust gas flowing into the first chamber  32  enters the catalyst device  40  via the pores  41 , and after the exhaust gas passes through the catalyst device  40 , the exhaust gas flows into the second chamber  33  via the pores  42 . 
     Since the diffuser pipe  50  is disposed between the connection portion of the exhaust pipe, and the placement position of the catalyst device  40 , a space in which the exhaust gas flowing into the first chamber  32  exists before entering the catalyst device  40  can be secured to be wide at this time, whereby the high-temperature exhaust gas flowing into the first chamber  32  from the exhaust pipe is cooled before flowing into the catalyst device  40 . As a result, it becomes possible to prevent the catalyst device  40  from being deteriorated by the high-temperature exhaust gas. 
     Further, since the exhaust gas is caused to flow into the catalyst device  40  via the pores  41  of the catalyst device  40 , it is possible to reduce a flow velocity of the exhaust gas, and it is possible to reduce occurrence of airflow noise. 
     The exhaust gas flowing in the second chamber  33  from the catalyst device  40  flows into the third chamber  34  via communication holes  35 , and flows into a lower end of the diffuser pipe  50  from the third chamber  34 . The exhaust gas flowing into the diffuser pipe  50  flows out to inside of the outer tube  51  via the pores  53  from the inner tube  52 , and flows to inside of the inner tube  52  via the pores  53  again. By repeating this, airflow noise and vibration sound can be reduced. 
     The exhaust gas flowing in the diffuser pipe  50  is released to an outside from the tail pipe  60  via the arrester  55 . 
     As described above, in the present embodiment, the casing  21  that is disposed vertically is included, and the top cover  22  and the undercover  23  (end cover) that are provided on a top and a bottom of the casing  21  are each formed into a substantially trapezoidal shape. 
     Thereby, as compared with a case where the top cover  22  and the undercover  23  are each formed into a planar shape, an inner capacity of the casing  21  can be secured to be large, and rigidity can be also enhanced. As a result, the size of the muffler device  20  can be reduced, and no extra parts are required, so that reduction in manufacturing cost and reduction in weight can be achieved. Further, since the casing  21  is disposed vertically, it is possible to install the casing  21  even when an installation space is small inside of the housing of the generator  1 , and it is possible to reduce the size of the generator  1 . 
     Further, in the present embodiment, the end cover is formed of the top cover  22  provided on the upper portion of the casing  21 , and the undercover  23  provided on the lower portion of the casing  21 , the inclined surface  24  is formed on the top surface of the top cover  22 , and the exhaust pipe and the tail pipe  60  are connected to the inclined surface  24  of the top cover  22 . 
     Thereby, it is possible to concentrate the connection portions of the exhaust pipe and the tail pipe  60  on the upper portion of the casing  21 , and it is possible to improve maintainability. 
     Further, in the present embodiment, the catalyst device  40  is included in the inside of the casing  21 , and the catalyst device  40  is disposed in the vertical direction. 
     Accordingly, it is possible to make it difficult for carbon inside of the catalyst device  40  to accumulate, by disposing the catalyst device  40  in the vertical direction. 
     Further, in the present embodiment, the diffuser pipe  50  is disposed between the connection portion of the exhaust pipe on the top cover  22 , and the placement position of the catalyst device  40 , in the inside of the casing  21 . 
     Accordingly, since the diffuser pipe  50  is disposed between the connection portion of the exhaust pipe, and the placement position of the catalyst device  40 , the space where the exhaust gas flowing in the casing  21  exits before entering the catalyst device  40  can be secured to be wide. As a result, the high-temperature exhaust gas flowing into the casing  21  from the exhaust pipe is cooled before flowing into the catalyst device  40 , and it becomes possible to prevent the catalyst device  40  from being deteriorated by the high-temperature exhaust gas. 
     Further, in the present embodiment, the diffuser pipe  50  extends over the substantially entire region in the up-down direction of the casing  21 , and the arrester  55  is disposed in the connection portion of the diffuser pipe  50  to the tail pipe  60 . 
     Accordingly, since the arrester  55  is disposed in the inside of the connection pipe  54  of the diffuser pipe  50 , it is possible to reduce the size while keeping the silencing function. 
     Note that the present invention is not limited to what is described in the above described embodiment, but various modifications and changes can be made within the range without departing from the gist of the present invention. 
     REFERENCE SIGNS LIST 
     
         
           1  Generator 
           10  Housing 
           20  Muffler device 
           21  Casing 
           22  Top cover 
           23  Undercover 
           24  Inclined surface 
           25  Exhaust hole 
           26  Tail pipe hole 
           30  First partition wall 
           31  Second partition wall 
           32  First chamber 
           33  Second chamber 
           34  Third chamber 
           35  Communication hole 
           40  Catalyst device 
           50  Diffuser pipe 
           51  Outer tube 
           52  Inner tube 
           54  Communication pipe 
           55  Arrester 
           60  Tail pipe