Abstract:
An exhaust device for a vehicle, the vehicle including a vehicle body, a fuel tank protruding from a bottom surface of the vehicle body, and a suspension system that supports first and second rear wheels to the vehicle body. The exhaust device is configured to be connected to a gas exhaust through-hole of an engine and includes a muffler that is disposed laterally alongside the fuel tank, with a length direction of the muffler disposed along a longitudinal direction of the vehicle body; a first exhaust pipe that connects an exhaust port of the engine to the muffler; and a second exhaust pipe connected to the muffler, and comprising a free end through which exhaust gas is exhausted. The number of mufflers is exactly one.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2006-0034855 filed in the Korean Intellectual Property Office on Apr. 18, 2006, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to an understructure of a vehicle on which an exhaust device is mounted, and to an exhaust device with exactly one muffler. 
         [0004]    (b) Description of the Related Art 
         [0005]    In general, a fuel tank, a suspension system, and an exhaust apparatus are mounted at a bottom of a vehicle. The fuel tank projects from a lower surface of the vehicle. The exhaust device includes a catalytic converter, a center muffler, a main muffler, a first exhaust pipe connecting an exhaust port of the engine to the catalytic converter, a second exhaust pipe connecting the catalytic converter to the center muffler, a third exhaust pipe connecting the center muffler to the main muffler, and a fourth exhaust pipe, one end of which is connected to the main muffler, and the other end of which is positioned near a rear end of the vehicle body. 
         [0006]    Resistance of exhaust gas increases while the exhaust gas passes through the two mufflers, and output of the engine may be decreased by such an increased resistance. 
         [0007]    In addition, part of the third exhaust pipe is disposed on a lower surface of the fuel tank, and is thus prone to be impacted on the ground. Life of the third exhaust pipe may be shortened by such an impact. 
         [0008]    Another part of the third exhaust pipe is disposed between the lower surface of the vehicle and the upper end of the suspension system. Since the third exhaust pipe is sharply bent to accomplish this disposition, manufacturing cost is high and the output of the engine may be deteriorated. 
         [0009]    In addition, the main muffler is positioned between the suspension system and the rear end of the vehicle body. Since the length between the suspension system and the rear end of the vehicle body varies with vehicle type, the main muffler must be specifically designed for each vehicle type. 
         [0010]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a vehicle with improved engine output and decreased exhaust noise. 
         [0012]    A vehicle according to an exemplary embodiment of the present invention includes a vehicle body; a fuel tank located below a rear seat and protruding from a bottom surface of the vehicle body; a suspension system that supports first and second rear wheels to the vehicle body; and an exhaust device connected to a gas exhaust through-hole of an engine and extending to a rear end of the vehicle body, wherein the exhaust device may comprise a muffler located laterally alongside the fuel tank, and disposed along a longitudinal direction of the vehicle body, a first exhaust pipe that connects an exhaust port of the engine to the muffler, and a second exhaust pipe connected to the muffler and extending to the rear end of the vehicle body. The number of mufflers included in the exhaust device may be exactly one. 
         [0013]    An inlet of the muffler may be located toward a front end of the vehicle body, and an outlet of the muffler may be located toward a rear end of the vehicle body. 
         [0014]    In addition, a gap between a first edge of the vehicle body and an edge of the muffler may have the same size as a gap between a second edge of the vehicle body and an edge of the fuel tank. 
         [0015]    The muffler may be configured and dimensioned such that the fuel tank extends beyond the muffler in forward, rearward, and downward directions. 
         [0016]    The muffler may include a case forming an inner space; a plurality of partitions dividing the inner space into several portions; and a plurality of inner pipes penetrating the plurality of partitions in the longitudinal direction of the vehicle body. One of the inner pipes may have a first end connected to the second exhaust pipe and a second end which is bent. 
         [0017]    The second exhaust pipe and the inner pipe that is connected thereto may be integrally formed. 
         [0018]    The suspension system may include a first supporting member that supports the first rear wheel; a second supporting member that supports the second rear wheel; a cross member connecting the first supporting member to the second supporting member; a first link member with a first end connected to a lower part of the first supporting member and a second end connected to a first predetermined portion on the cross member; and a second link member with a first end connected to a lower part of the second supporting member and a second end connected to a second predetermined portion on the cross member. The second exhaust pipe may pass through a bottom surface of the cross member. 
         [0019]    The first predetermined portion on the cross member may be located between ⅓ and ⅔ of the distance from a center of the cross member to the first rear wheel, and the second predetermined portion on the cross member may be located between ⅓ and ⅔ of the distance from the center of the cross member to the second rear wheel. 
         [0020]    The first predetermined portion on the cross member may be located at the halfway point from the center of the cross member to the first rear wheel, and the second predetermined portion on the cross member may be located at the halfway point from the center of the cross member to the second rear wheel. 
         [0021]    The second exhaust pipe may be located between the height of the bottom surface of the cross member and the height of the bottom surface of the fuel tank. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a bottom plan view showing a bottom surface of a vehicle according to an exemplary embodiment of the present invention. 
           [0023]      FIG. 2  is a cross-sectional view taken along line “II-II” in  FIG. 1 . 
           [0024]      FIG. 3  is a graph showing noise from a vehicle according to an exemplary embodiment of the present invention in comparison with noise from a conventional vehicle. 
           [0025]      FIG. 4  is a cross-sectional view of a muffler included in a vehicle according to an exemplary embodiment of the present invention. 
           [0026]      FIG. 5  is a drawing showing change of overall length of a vehicle body by a vehicle type according to an exemplary embodiment of the present invention. 
           [0027]      FIG. 6  is a cross-sectional view taken along line “VI-VI” in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art will realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0029]    As shown in  FIG. 1  and  FIG. 2 , a fuel tank  300  is located below a rear seat  110  ( FIG. 5 ) of the vehicle, and protrudes from a bottom surface  101  of a vehicle body  100 . The suspension system  500  supports first and second rear wheels W 1  and W 2  to the vehicle body  100 . The exhaust device  700 , which is connected to a gas exhaust through-hole  201  of an engine  200 , and extends to a rear end of the vehicle body  100 , discharges exhaust gas to a rear end of the vehicle body  100 . 
         [0030]    Referring to  FIG. 1 , the exhaust device  700  includes a first exhaust pipe  750  connected between the gas exhaust through-hole  201  and a muffler  730 , and a second exhaust pipe  770 , connected to the muffler  730 , extends to the rear end of the vehicle body  100 . 
         [0031]    The catalytic converter  710  is connected to the gas exhaust through-hole  201 , and purifies exhaust gas. 
         [0032]    The muffler  730 , which is located at a lateral side of the fuel tank  300  and disposed along a longitudinal direction of the vehicle body  100 , decreases noise. In some embodiments, only one muffler  730  is provided. Output of the engine can be improved by the decreased resistance of exhaust gas obtained by providing only one muffler  730 . 
         [0033]    When only one muffler  730  is included, a mounting position of the muffler  730  is important in order to effectively decrease exhaust noise. According to experiments, when muffler  730  is provided laterally alongside the fuel tank  300  and disposed along a longitudinal direction of the vehicle body  100  as described above, exhaust noise can be effectively decreased. 
         [0034]    It is further preferable that an inlet of the muffler is located toward a front end of the vehicle body  100 , and that an outlet of the muffler is located toward the rear end of the vehicle body  100 . 
         [0035]    As shown in  FIG. 3 , results of experiments using the muffler  730  disposed as described above show that an exhaust system according to an exemplary embodiment of the present invention decreases exhaust noise more than a conventional muffler when engine speed is 5000 RPM or less, but that it creates nearly the same amount of exhaust noise with the conventional muffler when engine speed is higher than 5000 RPM. 
         [0036]    Furthermore, as shown in  FIG. 4 , the muffler  730  may include a case  735  forming an inner space  735   a , a plurality of partitions  736  dividing the inner space  735   a  into several portions, and a plurality of inner pipes  737  penetrating the partitions  736  in the longitudinal direction of the vehicle body  100 . Therefore, exhaust gas may have less noise during passing through the several divided inner spaces, and it is finally discharged through the second exhaust pipe  770  at the outlet  732  of the muffler  730 . Particularly, an inner pipe  737   a  is connected to the second exhaust pipe  770 , and it is preferable that the inner pipe  737   a  has a bent end as shown at E in  FIG. 4 . When the inner pipe  737   a  has the bent end, length of the inner pipe can be resultantly extended, and noise can be more decreased because flow of exhaust gas is delayed as much as the extended length of the inner pipe. Particularly, when the inner pipe having the bent end is included in the muffler wherein sound pressure is high, noise can be further decreased. In addition, the second exhaust pipe  770  and the inner pipe  737   a  connected thereto may be integrally formed as a single member in order for the muffler to have a simple scheme. 
         [0037]    As shown in  FIG. 5 , when a single muffler  730  is provided at the lateral side of the fuel tank  300 , an expensive muffler need not be additionally designed because only the length of the second exhaust pipe  770  needs to be adjusted based on vehicle type even though lengths (refer to L 1 , L 2 ) between the suspension system  500  and the rear end of the vehicle body  100  vary with vehicle type, such as a first vehicle type A, a second vehicle type B, and a third vehicle type C. 
         [0038]    In addition, referring to  FIG. 2 , a gap G 1  between the left edge of the vehicle body  100  and the left edge of the muffler  730  may have the same dimensions as a gap G 2  between the right edge of the vehicle body  100  and the right edge of the fuel tank  300  in order to simplify the bottom of a vehicle. 
         [0039]    Referring to  FIG. 1 , the muffler  730  may be located between a front side  301  and rear side  302  of the fuel tank  300 . In addition, referring to  FIG. 2 , the muffler  730  may be also located between the bottom surface  101  of the vehicle body  100  and the bottom surface  303  of the fuel tank  300 . When the muffler  730  is located in the position described in the above, the fuel tank  300  can protect the muffler  730  from external impacts when the bottom of the vehicle body collides with the ground. 
         [0040]    Referring to  FIGS. 1 and 6 , the suspension system  500  may include a first supporting member  510 , which supports a first rear wheel (W 1 ), and a second supporting member  520 , which supports a second rear wheel (W 2 ). 
         [0041]    The suspension system  500  may further include a cross member  530 , which connects the first supporting member  510  to the second supporting member  520 . 
         [0042]    The suspension system  500  may further include a first link member  540 , one end of which is connected to a lower part of the first supporting member  510 , and another end of which is connected to a first predetermined portion  531  on the cross member  530 ; and a second link member  550 , one end of which is connected to a lower part of the second supporting member  520 , and another end of which is connected to a second predetermined portion  532  on the cross member  530 . 
         [0043]    The second exhaust pipe  770  passes through a bottom surface of the cross member  530 . It is preferable that one end of the first link member  540  and one end of the second link member  550  are connected to the cross member in the following scheme in order for the second exhaust pipe  770  to pass through the bottom surface of the cross member  530 . 
         [0044]    The first predetermined portion  531  may be located between ⅓ and ⅔ of the distance from the center CL of the cross member  530  to the first rear wheel (WI). In addition, the second predetermined portion  532  may be located between ⅓ and ⅔ of the distance from the center CL of the cross member  530  to the second rear wheel (W 2 ). Therefore, the second exhaust pipe  770  can pass between the first predetermined portion  531  on the bottom surface of the cross member  530  and the center CL of the cross member  530 . 
         [0045]    In some embodiments, the first predetermined portion  531  is located at the halfway point from the center CL of the cross member  530  to the first rear wheel (W 1 ). In addition, the second predetermined portion  532  is located at the halfway point from the center CL of the cross member  530  to the second rear wheel (W 2 ). 
         [0046]    As described above, a vehicle according to an exemplary embodiment of the present invention may provide the following advantages. 
         [0047]    Since only one muffler is included, output of engine can be improved, and manufacturing cost of the engine can be reduced. In addition, since the muffler is located at an optimal place, exhaust noise may be decreased. Furthermore, an expensive muffler need not be specifically designed for each vehicle type. 
         [0048]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.