Patent Publication Number: US-2009236174-A1

Title: Exhaust apparatus of vehicle engine

Description:
FIELD OF THE INVENTION 
     The present invention relates to an exhaust apparatus including a muffler device, which is provided in an exhaust system of a vehicle engine. 
     BACKGROUND OF THE INVENTION 
     Generally, an exhaust system of a vehicle engine is provided with an exhaust apparatus including a muffler device for lowering a temperature and a pressure of exhaust gas. As the exhaust apparatus mentioned above, at the demands in terms of an installing space of the muffler device in a lower surface of a vehicle, a horizontal muffler type exhaust apparatus is known, in which a tubular muffler device is provided in such a manner that a center axis extends along a lateral direction of the vehicle.  FIG. 5  shows a plan view of a typical horizontal muffler type exhaust apparatus. 
     As shown in  FIG. 5 , the exhaust apparatus is provided with a muffler device  110  forming an expansion chamber, and an exhaust pipe  120  for introducing exhaust gas to the muffler device  110  and discharging the exhaust gas from the muffler device  110 . The muffler device  110  has a circumferential surface portion  111  formed substantially in an elliptical tubular shape, and end plates  112  and  113  provided in such a manner as to cover both end opening portions of the circumferential surface portion  111 . Further, the muffler device  110  is installed in the vehicle in such a manner that a center axis C of the circumferential surface portion  111  extends along a lateral direction T of the vehicle (a direction orthogonal to a longitudinal direction of the vehicle). 
     A part of the exhaust pipe  120  extends in an interior of the muffler device  110  through an upstream through hole  112 A formed in the end plate  112  and a downstream through hole  113 A formed in the end plate  113 . The exhaust pipe  120  has an inlet portion  121  corresponding to a portion in an upstream side of the upstream through hole  112 A, and an outlet portion  122  corresponding to a portion in a downstream side of the downstream through hole  113 A. The inlet portion  121  has a first bent portion  121 A, and the outlet portion  122  has a second bent portion  122 A. Further, an opening portion  123  connecting an internal space of the exhaust pipe  120  with an internal space of the muffler device  110  is formed in a portion accommodated in the interior of the muffler device  110  in the exhaust pipe  120 . 
     Exhaust gas discharged from a plurality of cylinders of the engine is introduced into the interior of the muffler device  110  through an exhaust gas manifold connected to the cylinders, an exhaust gas catalyst device and the inlet portion  121 , and is diffused to the interior of the muffler device  110  through the opening portion  123 . The exhaust gas diffused as mentioned above repeatedly comes into collision with an inner wall of the muffler device  110 , whereby a temperature and a pressure thereof gradually are lowered, and is thereafter discharged to the outside through the outlet portion  122 . 
     In the horizontal muffler type exhaust apparatus as mentioned above, the bent portion  121 A of the inlet portion  121  and the bent portion  122 A of the outlet portion  122  are respectively arranged outside of the muffler device  110 . Accordingly, it is hard to make a length along the vehicle lateral direction T of the exhaust apparatus small without changing the shape of the muffler device  110 . Accordingly, it is impossible to disregard the constrain on the installing space, and types of vehicles to which the exhaust apparatus can be mounted are limited. 
     An exhaust apparatus shown in  FIG. 6  is disclosed in Japanese Laid-Open Patent Publication No. 8-58404. In this exhaust apparatus, an inlet portion  221  of an exhaust pipe  220  is formed in a straight pipe shape, and is structured such as to be connected to a circumferential surface portion  211  of a muffler device  210 . Accordingly, it is possible to reduce the length of the exhaust apparatus in a lateral direction T of a vehicle without changing the shape of the muffler device  210 . However, the exhaust apparatus has the following drawbacks with respect to a joint portion between the inlet portion  221  and the muffler device  210 . 
     Since the joint portion between the inlet portion  221  and the muffler device  210  exists on a peripheral edge portion of an upstream through hole  211 A formed in a curved surface shaped circumferential surface portion  211 , it is hard to provide adequate strength to the joint portion. 
     Further, since the joint portion between the inlet portion  221  and the muffler device  210  corresponds to a portion in which a temperature difference is large between an engine operating time and an engine stopping time, a fatigue of the joint portion caused by repetitive thermal expansion and the thermal contraction in accordance with temperature changes is great. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide an exhaust apparatus of a vehicle engine that maintains a high bonding strength of an exhaust pipe with respect to a muffler device, while keeping a margin of an installing space in a lateral direction of the vehicle. 
     In accordance with an aspect of the present invention, an engine exhaust apparatus comprising is provided. The apparatus includes a substantially elliptic tubular muffler device, an inlet portion, and an outlet portion. The tubular muffler device is mounted to a vehicle, and is provided in such a manner that a center axis extends along a lateral direction of the vehicle. The inlet portion introduces exhaust gas of an engine to the muffler device. The outlet portion discharges exhaust gas to the outside from the muffler device. The muffler device has a circumferential surface portion formed substantially in an elliptic tubular shape, and a pair of end plates provided in such a manner as to cover both end opening portions of the circumferential surface portion. The inlet portion is connected to one of the end plates, and the outlet portion is connected to the circumferential surface portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
         FIG. 1  is a perspective view of an engine exhaust apparatus according to one embodiment of the present invention; 
         FIG. 2  is a cross-sectional view of the exhaust apparatus in  FIG. 1 ; 
         FIG. 3  is a plan view showing an engine exhaust apparatus according to a modified embodiment of the present invention; 
         FIG. 4  is a plan view showing an engine exhaust apparatus according to another modified embodiment of the present invention; 
         FIG. 5  is a front elevational view of a typical engine exhaust apparatus; and 
         FIG. 6  is a front elevational view of another typical exhaust apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     A description will be given of an embodiment according to the present invention with reference to  FIGS. 1 and 2 .  FIG. 1  is a perspective view of an engine exhaust apparatus  1  in accordance with the present embodiment. The exhaust apparatus  1  is a horizontal muffler type exhaust apparatus. 
     As shown in  FIG. 1 , the exhaust apparatus  1  is provided with a muffler device  10  forming an expansion chamber, and an exhaust pipe  20  for introducing exhaust gas to the muffler device  10  and discharging exhaust gas from the muffler device  10 . The muffler device  10  has a circumferential surface portion (a tubular surface or a tubular wall)  11  formed substantially in an elliptic tubular shape, and first and second end plates (upstream and downstream end plates)  12  and  13  provided in such a manner as to cover both end opening portions of the circumferential surface portion  11 . The muffler device  10  is installed to a vehicle in such a manner that a portion having a large curvature in the circumferential surface portion  11 , that is, a portion having a small radius of curvature faces in a longitudinal direction of the vehicle. 
     In the end plates  12  and  13 , an upstream through hole  12 A is formed in the first end plate  12 , which is arranged a side through which exhaust gas discharged from the cylinders of the engine is introduced into the muffler device  10 . A downstream through hole  11 A is formed at a portion positioned in a rear side of the vehicle, in the portion having the large curvature in the circumferential surface portion  11  of the muffler device  10 . A part of the exhaust pipe  20  extends in the interior of the muffler device  10  through the upstream through hole  12 A and the downstream through hole  11 A. The exhaust pipe  20  has an inlet portion  21  corresponding to a portion in an upstream side of the upstream through hole  12 A, and an outlet portion  22  corresponding to a portion in a downstream side of the downstream through hole  11 A. The inlet portion  21  is connected to the muffler device  10  in a state of having a bent portion  21 A outside of the muffler device  10 . The outlet portion  22  is constituted by a pipe formed in a straight pipe shape. The inlet portion  21  and the outlet portion  22  are connected via a relay portion arranged in the interior of the muffler device  10  mentioned above. In the present embodiment, both of the muffler device  10  and the exhaust pipe  20  are formed of a stainless steel. 
       FIG. 2  shows a cross-sectional view of the exhaust apparatus  1  in  FIG. 1 . In  FIG. 2 , a first center line C 1  is a line dividing a long diameter of the circumferential surface portion  11  into two equal parts, and corresponds to a center axis of the circumferential surface portion  11 . A second center line C 2  is orthogonal to the first center line C 1 , and is a line dividing the muffler device  10  into two equal parts in a direction of the first center line C 1 . The first center line C 1  extends along a vehicle lateral direction T, and the second center line C 2  extends along the vehicle longitudinal direction. 
     As shown in  FIG. 2 , an upstream guide portion (an upstream support portion)  12 B for supporting the inlet portion  21  of the exhaust pipe  20  is formed in the first end plate (the upstream end plate)  12  in such a manner as to extend toward the outside of the muffler device  10 . The upstream guide portion  12 B is formed in a tubular shape, and is provided on the peripheral edge of the upstream through hole  12 A mentioned above. The upstream guide portion  12 B is provided at a position which is shifted toward the upstream side of the muffler device  10 , that is, a position which is shifted toward an upper side in  FIG. 2  with respect to the first center line C 1 . The inlet portion  21  is fixed to the upstream guide portion  12 B in accordance with a welding. 
     In the interior of the muffler device  10 , the inlet portion  21  and the outlet portion  22  are connected to each other via a relay pipe  23  corresponding to a relay portion. The relay pipe  23  has a curved portion  23 A, and a communication hole  23 B is formed in the curved portion  23 A. An expansion pipe  24  guiding the exhaust gas introduced from the inlet portion  21  through the communication hole  23 B to the internal space of the muffler device  10  so as to diffuse the exhaust gas extends from the curved portion  23 A. The expansion pipe  24  has a proximal end portion  24 A communicating with the communication hole  23 B, and a distal end portion  24 B communicating with the internal space of the muffler device  10 . The proximal end portion  24 A is fixed to the relay pipe  23  on a peripheral edge of the communication hole  23 B through welding. 
     A downstream guide portion (a downstream support portion)  11 B for supporting the outlet portion  22  is formed in the circumferential surface portion  11  in such a manner as to extend toward the outside of the muffler device  10 . The downstream guide portion  11 B is formed in a tubular shape, and is provided on a peripheral edge of the downstream through hole  11 A. The downstream guide portion  11 B is provided at a position which is shifted toward the downstream side of the muffler device  10 , that is, a position which is shifted toward a right side in  FIG. 2  with respect to the second center line C 2 . In other words, the downstream guide portion  11 B is provided at a position close to the second end plate  13 . In other words, the downstream guide portion  11 B is provided at a position which is in an opposite side to the upstream guide portion  12 B with respect to the first center line C 1 , and is in an opposite side to the upstream guide portion  12 B with respect to the second center line C 2 . In other words, the upstream guide portion  12 B and the downstream guide portion  11 B are provided at diagonal positions in the muffler device  10 . The outlet portion  22  is fixed to the downstream guide portion  11 B in accordance with a welding. 
     As mentioned above, the exhaust apparatus  1  in accordance with the embodiment is formed as such a structure that a partition plate is not provided in the interior of the muffler device  10 , that is, such a structure that the exhaust pipe  20  is supported to the muffler device  10  only by the upstream guide portion  12 B and the downstream guide portion  11 B. In other words, the exhaust gas discharged from the cylinders of the engine is introduced to the muffler device  10  through an exhaust manifold connected to the cylinders, an exhaust gas catalyst device and the inlet portion  21  of the exhaust pipe  20 . The exhaust gas introduced to the muffler device  10  is introduced to the internal space of the muffler device  10  through the relay pipe  23  and the expansion pipe  24  so as to be diffused. The diffused exhaust gas repeatedly comes into collision with the inner wall of the muffler device  10 , whereby the temperature and pressure thereof are gradually lowered. Thereafter, the exhaust gas is discharged to the outside through the outlet portion  22  of the exhaust pipe  20 . 
     Next, a description will be given below of advantages of the present embodiment. 
     (1) The inlet portion  21  of the exhaust pipe  20  is connected to the end plate  12  of the muffler device  10  arranged laterally with respect to the vehicle. Accordingly, in comparison with the exhaust apparatus having the structure that the inlet portion is connected to the circumferential surface portion of the muffler device, as shown in Japanese Laid-Open Patent Publication No. 8-58404, it is possible to provide a high strength to the joint portion between the inlet portion and the end plate. 
     Since the outlet portion  22  of the exhaust pipe  20  mentioned above is connected to the circumferential surface portion  11  of the muffler device  10  mentioned above, it is possible to shorten the length of the exhaust apparatus  1  in the direction extending along the center line C 1 , that is, the vehicle lateral direction T. 
     (2) The muffler device  10  is installed in such a manner that the portion having the large curvature in the circumferential surface portion  11  faces in the longitudinal direction of the vehicle. Accordingly, the installation space necessary in the vehicle height direction can be reduced. 
     (3) The inlet portion  21  of the exhaust pipe  20  is connected to the position which is shifted toward the upstream side of the muffler device  10 , in the end plate  12 . The outlet portion  22  of the exhaust pipe  20  is connected to the position which is shifted toward the downstream side of the muffler device  10 , in the circumferential surface portion  11 . In other words, the upstream guide portion  12 B and the downstream guide portion  11 B are provided at the diagonal positions in the muffler device  10  in such a manner as to be spaced as largely as possible in a three-dimensional manner. Accordingly, it is possible to more effectively make good use of the internal space of the muffler device  10 . Also, it is possible to lower the temperature of the exhaust gas near the outlet portion  22 , and to reduce the range of changes in the temperature. As a result, it is possible to maintain a higher bonding strength in the joint portion between the outlet portion  22  and the muffler device  10 . 
     (4) The inlet portion  21  of the exhaust pipe  20  is connected to the muffler device  10  in the manner having the bent portion  21 A outside of the muffler device  10 , and the outlet portion  22  of the exhaust pipe  20  is connected as the pipe formed in the straight pipe shape to the muffler device  10 . Accordingly, it is possible to install the exhaust apparatus  1  efficiently in terms of space with respect to the vehicle. Since the rigidity in the joint portion between the inlet portion  21  and the end plate  12  is sufficiently high, there is a risk that the rigidity in the bent portion  21 A of the inlet portion  21  becomes relatively low in comparison with that in the joint portion between the inlet portion  21  and the end plate  12 . However, since the outlet portion  22  is connected as the pipe formed in the straight pipe shape to the circumferential surface portion  11  of the muffler device  10 , the rigidity of the joint portion between the outlet portion  22  and the circumferential surface portion  11  becomes lower than that in the joint portion with the end plate  12  in the same manner as the bent portion  21 A. Accordingly, the rigidity balance in the entire exhaust apparatus  1  is maintained in a favorable manner. 
     The exhaust apparatus  1  of the vehicle engine in accordance with this invention is not limited to the structure exemplified in the embodiment mentioned above, but may be carried out, for example, as the following modifications of the above embodiment. 
     The connecting position of the inlet portion  21  to the end plate  12 , and the connecting position of the outlet portion  22  to the circumferential surface portion  11  are not limited to the illustrated embodiment. Each of the connecting positions may be set to positions described in the following items (A) and (B). 
     (A) In an embodiment shown in  FIG. 3 , an upstream through hole  312 A is formed in such a manner as to be positioned on a first center line C 1  in an end plate  312  of a muffler device  310 . An inlet portion  321  of an exhaust pipe  320  is connected to the upstream through hole  312 A. A connecting position of an outlet portion  322  of the exhaust pipe  320  is the same as the embodiment mentioned above. In other words, a downstream through hole  311 A is formed at a position which is shifted toward an end plate  313  (a right side in  FIG. 3 ) than a second center line C 2 , in a circumferential surface portion  311  of the muffler device  310 , and the outlet portion  322  is fixed to the circumferential surface portion  311  in such a manner as to pass through the downstream through hole  311 A. 
     (B) In an embodiment shown in  FIG. 4 , a downstream through hole  411 A is formed in such a manner as to be positioned on a second center line C 2 , in a circumferential surface portion  411  of a muffler device  410 , and an outlet portion  422  is fixed to the circumferential surface portion  411  in such a manner as to pass through the downstream through hole  411 A. A connecting position of an inlet portion  421  of the exhaust pipe  420  is the same as the embodiment mentioned above. In other words, an upstream through hole  412 A is formed at a position which is shifted toward an upstream side (an upper side in  FIG. 4 ) of the muffler device  10  than a first center line C 1 , with respect to an end plate  412  of the muffler device  410 , and the inlet portion  421  of the exhaust pipe  420  is fixed to the end plate  412  in such a manner as to pass through the upstream through hole  412 A. 
     In other words, it is sufficient that the inlet portion and the outlet portion are arranged in such a manner that the distance between the joint portions thereof to the muffler device becomes as large as possible in a three-dimensional manner. That is, it is sufficient that at least one of the inlet portion and the outlet portion is provided at the position which is shifted from the first or second center line C 1  or C 2  of the muffler device. 
     In the case that the muffler device is installed in the vehicle in such a manner that the portion having the small curvature faces the backward and forward sides of the vehicle in the circumferential surface portion of the muffler device, the outlet portion may be connected to the portion having the small curvature in the circumferential surface portion. 
     In addition, as long as the internal space of the muffler device is effectively utilized, the connecting positions of the inlet portion and the outlet portion of the exhaust pipe to the muffler device may be set as follows. That is, the structure may be made such that the inlet portion is connected so as to be on the first center line C 1  with respect to the upstream end plate of the muffler device, and the outlet portion is connected so as to be on the second center line C 2  with respect to the circumferential surface portion. Further, the structure may be made such that the inlet portion is connected a position which is shifted toward the downstream side of the muffler device than the first center line C 1 , and the outlet portion is connected closer to the upstream end plate than the second center line C 2  with respect to the circumferential surface portion. 
     In short, the muffler device may be structured such that both end surfaces are formed so as to have the substantially elliptic tubular shape closed by the end plate, the inlet portion of the exhaust pipe is connected to the upstream end plate of the muffler device, and the outlet portion of the exhaust pipe is connected to the circumferential surface portion.