Abstract:
A vehicle exhaust system has a first exhaust pipe adapted to be connected to a first exhaust port of an engine, a first expansion chamber connected to the first exhaust pipe, a second exhaust pipe adapted to be connected to a second exhaust port of an engine, a second expansion chamber connected to the second exhaust pipe, a collector connected to the first and second expansion chambers, a third exhaust pipe connected to the collector, and a first muffler connected to the third exhaust pipe. A vehicle having the vehicle exhaust system is also disclosed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an exhaust system for a vehicle. 
     BACKGROUND 
     Vehicles powered by internal combustion engines are provided with exhaust systems connected to the exhaust ports of the engine. The design of the exhaust system has an effect on the power output of the engine, the noise level and sound signature generated by the engine. The exhaust system also assists in controlling the pollution generated by the engine. However, the design choices for an exhaust system that maximizes power output are generally contradictory to the design choices for an exhaust system that minimizes noise level and optimizes sound signature. A reasonable trade-off therefore has to be reached in the design. 
     In order to maximize power, it is known to have long exhaust pipes connected to the exhaust ports. In order to minimize noise, it is known to include expansion chambers such as resonator and mufflers in the exhaust system. Long exhaust pipes and expansion chambers take a lot of room in a vehicle. 
     In many vehicles, such as off-road side-by-side vehicles (SSVs), the amount of room available for the various vehicle components is limited. In a SSV for example, the cockpit area has low seats, therefore providing very little room for components under the seats, and most of the remaining volume has to be free in order to accommodate the riders of the vehicle. The portions of the SSV forward and rearward of the cockpit area are relatively short and mostly occupied by the drive train and suspension components (and steering components at the front), thus leaving little room for other components. Also, in view of the operating conditions of SSVs, typically rough, unpaved terrain, designers of SSVs try as much as possible not to have any components extending below the frame of the vehicle as these could get damaged. As such, there is not a lot of room to place components of an exhaust system, especially one with long exhaust pipes and expansion chambers. 
     There is therefore a need for an exhaust system for a vehicle which provides an acceptable trade-off between engine power output and noise level while fitting in a limited amount of space. 
     SUMMARY 
     It is an object of the present invention to ameliorate at least some of the inconveniences present in the prior art. 
     In one aspect, embodiments of the present invention provide a vehicle exhaust system having a first exhaust pipe adapted to be connected to a first exhaust port of an engine, a first expansion chamber connected to the first exhaust pipe, a second exhaust pipe adapted to be connected to a second exhaust port of an engine, a second expansion chamber connected to the second exhaust pipe, a collector connected to the first and second expansion chambers, a third exhaust pipe connected to the collector, and a first muffler connected to the third exhaust pipe. 
     In an additional aspect, a fourth exhaust pipe is connected to the collector, and a second muffler is connected to the fourth exhaust pipe. 
     In a further aspect, a catalytic converter is connected downstream of the collector and upstream of the third exhaust pipe. 
     In an additional aspect, exhaust gases from the first and second exhaust pipes flow through the catalytic converter. 
     In a further aspect, the first and second expansion chambers are adjacent to each other. 
     In an additional aspect, the first and second expansion chambers are received in part inside the collector. 
     In a further aspect, the first expansion chamber is a first resonator and the second expansion chamber is a second resonator. 
     In an additional aspect, the first exhaust pipe extends through the first resonator. The first exhaust pipe has an end disposed inside the collector. A portion of the first exhaust pipe disposed inside the first resonator defines at least one aperture fluidly communicating the first exhaust pipe with the first resonator. The second exhaust pipe extends through the second resonator. The second exhaust pipe has an end disposed inside the collector. A portion of the second exhaust pipe disposed inside the second resonator defines at least one aperture fluidly communicating the second exhaust pipe with the second resonator. 
     In a further aspect, each of the first and second exhaust pipes is longer than each of the third and fourth exhaust pipes. 
     In an additional aspect, a flow of exhaust gases inside the first exhaust pipe and the first expansion chamber is separate from a flow of exhaust gases inside the second exhaust pipe and the second expansion chamber. The flow of exhaust gases from the first exhaust pipe and the first expansion chamber is mixed with the flow of exhaust gases from the second exhaust pipe and the second expansion chamber inside the collector. 
     In another aspect, embodiments of the present invention provide a vehicle having a frame and an internal combustion engine mounted to the frame. The internal combustion engine has a first exhaust port and a second exhaust port. A first exhaust pipe is connected to the first exhaust port. A first expansion chamber is connected to the first exhaust pipe. The first expansion chamber is disposed rearward of the engine. A second exhaust pipe is connected to the second exhaust port. A second expansion chamber is connected to the second exhaust pipe. The second expansion chamber is disposed rearward of the engine. A collector is connected to the first and second expansion chambers. A third exhaust pipe is connected to the collector. A first muffler is connected to the third exhaust pipe, the first muffler being disposed rearward of the collector. 
     In a further aspect, a fourth exhaust pipe is connected to the collector, and a second muffler is connected to the fourth exhaust pipe. The second muffler is disposed rearward of the collector. 
     In an additional aspect, a catalytic converter is connected downstream of the collector and upstream of the third exhaust pipe. 
     In a further aspect, exhaust gases from the first and second exhaust pipes flow through the catalytic converter. 
     In an additional aspect, the first and second expansion chambers are adjacent to each other. 
     In a further aspect, the first and second expansion chambers are received in part inside the collector. 
     In an additional aspect, the first expansion chamber is a first resonator and the second expansion chamber is a second resonator. 
     In a further aspect, the first exhaust pipe extends through the first resonator. The first exhaust pipe has an end disposed inside the collector. A portion of the first exhaust pipe disposed inside the first resonator defines at least one aperture fluidly communicating the first exhaust pipe with the first resonator. The second exhaust pipe extends through the second resonator. The second exhaust pipe has an end disposed inside the collector. A portion of the second exhaust pipe disposed inside the second resonator defines at least one aperture fluidly communicating the second exhaust pipe with the second resonator. 
     In an additional aspect, each of the first and second exhaust pipes is longer than each of the third and fourth exhaust pipes. 
     In a further aspect, the engine is a V-type engine having a first cylinder and a second cylinder. The first exhaust port fluidly communicates with the first cylinder and faces generally toward a front of the vehicle. The second exhaust port fluidly communicates with the second cylinder and faces toward a rear of the vehicle. 
     In an additional aspect, a driver seat is mounted to the frame. The driver seat has a seat bottom and a backrest. Two front wheels are mounted to the frame forwardly of the driver seat. Two rear wheels are mounted to the frame rearward of the driver seat. The first expansion chamber, the second expansion chamber and the collector are disposed rearward of the backrest. 
     In a further aspect, each of the two rear wheels rotate about a rear wheel rotation axis. The first expansion chamber, the second expansion chamber and the collector are disposed forwardly of the rear wheel rotation axes. 
     In an additional aspect, a cargo rack is mounted to the frame rearward of the backrest. The first expansion chamber, the second expansion chamber and the collector are disposed at least in part below the cargo rack. 
     In a further aspect, a driver seat is mounted to the frame. The driver seat has a seat bottom and a backrest. Two front wheels are mounted to the frame forwardly of the driver seat. Two rear wheels are mounted to the frame rearward of the driver seat. A cargo rack is mounted to the frame rearward of the backrest. The first and second mufflers are disposed at least in part below the cargo rack. 
     In an additional aspect, the first and second mufflers are disposed on opposite sides of a longitudinal centerline of the vehicle. 
     In a further aspect, the first and second expansion chambers each have an inlet. The inlets are disposed on a same side of a longitudinal centerline of the vehicle. 
     In an additional aspect, a flow of exhaust gases inside the first exhaust pipe and the first expansion chamber is separate from a flow of exhaust gases inside the second exhaust pipe and the second expansion chamber. The flow of exhaust gases from the first exhaust pipe and the first expansion chamber is mixed with the flow of exhaust gases from the second exhaust pipe and the second expansion chamber inside the collector. 
     For purposes of the present application, terms related to spatial orientation when referring to a vehicle, such as, but not limited to, “forwardly”, “rearward”, “front”, “rear”, “above”, “below”, “left” and “right”, are as they would be understood by a driver of the vehicle sitting in the vehicle in a normal driving position, with the vehicle in a straight ahead orientation (i.e. not steered left or right). Terms related to spatial orientation when referring to a component of the vehicle should be understood as they would be understood when the component is installed in the vehicle. 
     Embodiments of the present invention each have at least one of the above-mentioned object and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present invention that have resulted from attempting to attain the above-mentioned object may not satisfy this object and/or may satisfy other objects not specifically recited herein. 
     Additional and/or alternative features, aspects and advantages of embodiments of the present invention will become apparent from the following description, the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where: 
         FIG. 1  is a perspective view of a vehicle taken from a front, left side thereof; 
         FIG. 2  is a left side elevation view of a frame, seats, exhaust system and rear wheels support and drive mechanism of the vehicle of claim  1 ; 
         FIG. 3  is a rear elevation view of the portions of the vehicle of  FIG. 3 ; 
         FIG. 4  is a top plan view of the frame and exhaust system of the vehicle of  FIG. 1 ; 
         FIG. 5  is a right side elevation view of the frame, engine and exhaust system of the vehicle of  FIG. 1 ; 
         FIG. 6  is a top plan view of the exhaust system of the vehicle of  FIG. 1 ; 
         FIG. 7  is a left side elevation view of the exhaust system of  FIG. 6 ; 
         FIG. 8  is a right side elevation view of the exhaust system of  FIG. 6 ; 
         FIG. 9  is a front elevation view of the exhaust system of  FIG. 6 ; 
         FIG. 10  is a rear elevation view of the exhaust system of  FIG. 6 ; 
         FIG. 11  is a perspective view taken from a rear, right side of the exhaust system of  FIG. 6 ; 
         FIG. 12  is a cross-sectional view of the exhaust system of  FIG. 6  taken through line A-A of  FIG. 11 ; and 
         FIG. 13  is a cross-sectional view of an alternative embodiment of the exhaust system of  FIG. 6  with an alternative embodiment of expansion chambers. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention will be described with respect to an off-road side-by-side vehicle (SSV). However, it contemplated that aspects of the embodiments of the present invention could also be used on other types of wheeled vehicles, such as, but not limited to, all-terrain vehicles (ATVs), motorcycles and snowmobiles. 
       FIG. 1  illustrates a SSV  10  having a front end  12  and a rear end  14 . The SSV  10  includes a frame  16  to which a vehicle body is mounted. The frame  16  will be described in greater detail below. A pair of front wheels  18  is suspended from the front portion of the frame  16  via front suspensions  20 . A pair of rear wheels  22  is suspended from the rear portion of the frame  16  via rear suspensions  24 . Each of the four wheels  18 ,  22  has a tire  26 . It is also contemplated that the SSV  10  could have six or more wheels. 
     A cockpit area  28  is disposed in the middle portion of the frame  16 . The cockpit area  28  comprises a driver seat  30  and a passenger seat  32  mounted laterally beside each other to the frame  16  to accommodate a driver and a passenger (riders) of the SSV  10  respectively. Each seat  30 ,  32  has a seat bottom  34  and a backrest  36 . The cockpit area  28  is open at the two lateral sides of the SSV  10 , forming two lateral passages  38  through which the riders can ingress and egress the SSV  10 . A lateral cover (not shown), selectively disposed across each lateral passage  38 , can be opened to clear the lateral passage  38  for egress or ingress. A cargo rack  40  is mounted to the frame  16  rearward of the backrests  36  of the seats  30 ,  32  as will be described in greater detail below. The cargo rack  40  is surrounded in part by two side body panels  42 . A roll cage  46  is connected to the frame  16  and disposed above the cockpit area  28 . 
     An internal combustion engine  48  (shown schematically in  FIG. 5 ) is mounted to the middle portion of frame  16  between the seats  30 ,  32 . In the illustrated embodiment of the SSV  10 , the engine  48  is a V-type engine having a front cylinder  50  and a rear cylinder  52  disposed at an angle to each other. Each cylinder  50 ,  52  has an intake port and an exhaust port (not shown). The intake ports are connected to an air intake manifold  54  (schematically shown in  FIG. 5 ). The intake manifold  54  is connected to a throttle body (not shown) regulating the flow of air to the engine  48 . The exhaust port of the front cylinder  50  faces generally toward the front of the SSV  10 . The exhaust port of the rear cylinder  52  faces generally toward the rear of the SSV  10 . The exhaust ports are connected to the exhaust system  200  described below. It is contemplated that other types of internal combustion engine could be used, such as, for example, an inline engine. It is also contemplated that the engine  48  could have more than two cylinders  50 ,  52  and that the intake and exhaust ports could be oriented differently. A console  56 , positioned between seats  30 ,  32  covers the engine  48 . 
     A steering assembly including a steering wheel  58  is disposed in front of the driver seat  30 . The steering assembly is operatively connected to the two front wheels  18  to permit steering of the SSV  10 . 
     Each front suspension  20  includes lower and upper A-arms  60  pivotally connected at one end to the frame  16 , and at the other end to the corresponding front wheel  18 . A shock absorber  62  is connected between the outer end of each upper A-arm  60  and the frame  16 . A sway bar (not shown), disposed rearward of the front suspensions  20 , is connected to both upper A-arms  60  to increase the roll stiffness of the front suspensions  20 . 
     Each rear suspension  24  includes lower and upper A-arms  64  ( FIGS. 2 and 3 ) pivotally connected at one end to the frame  16 , and at the other end to the corresponding rear wheel  22 . As can be seen in  FIG. 2 , the upper A-arm  64  of each rear suspension  24  is pivotally connected by a linkage  65  to a swing arm  66 . The swing arm  66  is disposed below the upper A-arm  64  and is pivotally connected to the frame  16  about an axis that is forward of the A-arms  64 . A shock absorber  67  ( FIG. 1 ) is connected between the outer end of each upper A-arm  64  and the frame  16 . Toe links  68  are pivotally connected at one end to the frame  16 , and at the other end to their corresponding rear wheel  22  to maintain the rear wheels  22  in a generally straight ahead orientation. The length of the toe links  68  can be adjusted to give the rear wheels  22  some toe in or some toe out. 
     To drive the front wheels  18 , the engine  48  is connected to a front driveshaft (not shown), which is in turn connected to a front differential (not shown). The front differential transfers the torque from the front driveshaft to left and right half-shafts  70  (only one of which is shown in  FIG. 1 ). The half-shafts  70  are connected to their respective front wheels  18 . Similarly, to drive the rear wheels  22 , the engine  48  is connected to a rear driveshaft (not shown), which is in turn connected to a rear differential  72  (best seen in  FIG. 3 ). The rear differential  72  transfers the torque from the rear driveshaft to left and right half-shafts  74  ( FIG. 3 ). The half-shafts  74  are connected to their respective rear wheels  22 . 
     The SSV  10  has other features and components such as headlights and handles. As it is believed that these features and components would be readily recognized by one of ordinary skill in the art, further explanation and description of these components will not be provided herein. 
     Turning now to  FIGS. 2 to 5 , the frame  16  of the vehicle will be described in more detail. For simplicity, only the main elements of the frame  16  will be described. It is contemplated that the SSV  10  could have a frame  16  that is different from the one described below. The frame  16  has a central frame portion  76 , a front frame portion  78  connected to the front of the central fame portion  76  and a rear frame portion  80  connected to the back of the central frame portion  76 . As can be seen in  FIG. 4 , the front and rear frame portions  78 ,  80  are narrower than the central frame portion  76 . 
     The central frame portion  76  defines, together with the roll cage  46 , the cockpit area  28 . The central frame portion  76  is also used to mount the seats  30 ,  32  and the engine  48 . The central frame portion  76  has a front upper lateral member  82  and a rear upper lateral member  84 . A frame member  86  extends downward and rearward from each end of the front upper lateral member  76  and then bends near a bottom of the frame  16  to extend longitudinally rearward. Frame members  88  extend between the rearward ends of the frame members  86  to the ends of the rear upper lateral member  84 . A cross-member  89  extends laterally between the members  88 . The lower portions of the frame members  86  connect via cross-members  90  to a lower rectangular frame assembly  92 . The frame assembly  92  supports the engine  48 . Member  93  extends upward and rearward from the frame assembly  92  to the rear upper lateral member  84 . Members  94  extend downwardly from the front upper lateral member  82 . Plates  96  extend between the front of the frame assembly  92  and the front frame portion  78 . A longitudinal member  98  extends longitudinally between the seats  30 ,  32 . The member  98  is connected at its front end to the front frame portion  78  and at its rear end to the rear frame portion  80 . A U-shaped bar  100  is connected at its ends to the ends of the front upper lateral member  82  and the member  98 . The U-shaped bar  100  extends upward and rearward from the front upper lateral frame member  82 . Another U-shaped bar  102  is connected to the right side of the U-shaped bar  100 . The U-shaped bar  102  serves has a grab bar for the passenger of the SSV  10 . Seat frames  104  are connected to the cross-members  90 , the lower rectangular frame assembly  92 , the frame members  88 , and the longitudinal member  98 . The seats  30 ,  32  are mounted to the seat frames  104 . 
     The front frame portion  78  provides the connection points for the front suspensions  20  and is used to mount the front differential. The front frame portion  78  has upper and lower trusses  106 ,  108  connected to the members  94  of the central frame portion  76 . Two triangular frame assemblies  110  are connected to the front of the trusses  106 ,  108 . Each triangular frame assembly  110  provides mounting points for its corresponding front suspension  20 . A bumper  112  is connected to the front of the frame assemblies  110 . 
     The rear frame portion  80  provides the connection points for the rear suspensions  24  and is used to mount the rear differential  72 . The rear frame portion  80  has a trapezoidal frame assembly  114  connected at its front to the rear of the lower rectangular frame assembly  92 . Two members  116  are disposed above the assembly  114 . The members  116  are connected at their fronts to the cross-member  89  and extend rearward therefrom parallel to the sides of the assembly  92 . Brackets  118  connect the rear of the members  116  to the rear of the assembly  114 . Brackets  120  are also connected between the members  116  and the sides of the assembly  114  forward of the brackets  118 . The brackets  118 ,  120  provide the attachment points for the A-arms  64  of the rear suspensions  24 . The rear differential  72  sits in the space defined by the assembly  114  and the members  116 . Members  122  connect to the rear ends of the members  116  and extend upward, forward, and laterally outward therefrom to the rear upper lateral member  84 . A cross-member  124  is connected between the members  122 . A generally trapezoidal-shaped tube  126  is connected by members  128  to the rear upper lateral member  84  so as to be disposed higher than the member  84 . The tube  126  has a number of brackets  130  ( FIG. 4 ) used to fasten the cargo rack  40  to the tube  128 . A member  132  extends downward and forward from the rear part of the tube  126  to the cross-member  124 . The member  132  is disposed along the longitudinal centerline  134  of the SSV  10 . 
     Turning now to  FIGS. 6 to 12 , the exhaust system  200  will be described in more detail. The exhaust system  200  has an exhaust pipe  202  connected at one end to one exhaust port of the engine  48  and to an expansion chamber  204  at the other end and an exhaust pipe  206  connected at one end to the other exhaust port of the engine  48  and to an expansion chamber  208  at the other end. Both expansion chambers  204 ,  208  are connected to a collector  210 . The collector  210  is connected to a catalytic converter  212  which is itself connected to a fitting  214 . Two exhaust pipes  216 ,  218  are connected at one end to the fitting  214 . The other end of the exhaust pipe  216  is connected to a muffler  220 . The other end of the exhaust pipe  218  is connected to a muffler  222 . It is contemplated that the exhaust pipe  218  and the muffler  222  could be omitted. 
     During operation of the engine  48 , exhaust gases from the front cylinder  50  of the engine  48  flow in the exhaust pipe  202  and then in the expansion chamber  204 , and exhaust gases from the rear cylinder  52  of the engine  48  flow in the exhaust pipe  206  and then in the expansion chamber  208 . From the expansion chambers  204 ,  208  the flows of exhaust gases mix inside the collector  1210 . It should be noted that the flow of exhaust gases inside the exhaust pipe  202  and the expansion chamber  204  remains separate from the flow of exhaust gases inside the exhaust pipe  206  and the expansion chamber  208  until the two flows are mixed in the collector  210 . From the collector  210 , the exhaust gases then flow through the catalytic converter  212 . From the catalytic converter  212 , the exhaust gases then enter the fitting  214  and are separated into two separate flows. From the fitting  214 , part of the exhaust gases flow inside the exhaust pipe  216 , then into the muffler  220  and out to the atmosphere, and part of the exhaust gases flow inside the exhaust pipe  218 , then into the muffler  222  and out to the atmosphere. 
     The various components of the exhaust system  200  will now be described in more detail 
     The exhaust pipe  202  has two main pipe sections  224 ,  226 . It is contemplated that the exhaust pipe  202  could be made of a single pipe or of more than two main pipe sections. The pipe section  224  has a flange  228  used to fasten the exhaust pipe  202  to the front of the front cylinder  50  such that the end of the exhaust pipe  202  fluidly communicates with the exhaust port of the cylinder  50 . The end of the exhaust pipe  202  that fluidly communicates with the exhaust port of the cylinder  50  is disposed on a right side of the longitudinal centerline  134  ( FIG. 6 ). From the exhaust port, the pipe section  224  extends forward and downward, then rearward, downward and toward the left of the SSV  10 , then rearward, and finally rearward, upward and toward the right of the SSV  10 . As a result, the pipe section  224  passes under the driver seat  30 . The downstream end of the pipe section  224  is inserted into the upstream end of the pipe section  226 . A flange  230  on the downstream end of the pipe section  224  is fastened to a flange  232  on the upstream end of the pipe section  226  via spring-loaded fasteners  234 . A support  236  welded to the downstream portion of the pipe section  224  is used to connect the exhaust pipe  202  to a bracket (not shown) on the central frame portion  76 . A rubber damper  238  disposed between the support  236  and the bracket reduces the transmission of vibrations between the frame  16  and the exhaust system  200 . From its upstream end, the pipe section  226  extends rearward, upward and toward the right of the SSV  10  into the expansion chamber  204 . As best seen in  FIG. 12 , the pipe section  226  then extends through the expansion chamber  204  and its downstream end is disposed and opens inside the collector  210 . The inlet  240  of the expansion chamber  204  (i.e. the aperture through which the pipe section  226  enter the expansion chamber  204 ) is disposed on a left side of the longitudinal centerline  134 . The portion of the pipe section  226  that is disposed inside the expansion chamber  204  has a plurality of apertures  242  fluidly communicating that portion of the pipe section  226  with the interior of the expansion chamber  204 . It is contemplated that there could be more or less apertures  242  and/or that the apertures  242  could be relatively bigger or smaller than illustrated. As such, the expansion chamber  204  in the present embodiment is a resonator. Sound absorbing material  244  is provided inside the expansion chamber  204  around the pipe section  226 . It is contemplated that the sound absorbing material  244  could be omitted. As can be seen, the exhaust pipe  202  is longer than the exhaust pipes  216 ,  218 . As can be seen in  FIGS. 2 to 5 , the expansion chamber  204  is disposed rearward of the engine  48  and the backrests  36 , forward of the rotation axes  136  of the rear wheels  22 , and in part below the cargo rack  40 . 
     The exhaust pipe  206  has four main pipe sections  246 ,  248 ,  250 ,  252 . It is contemplated that the exhaust pipe  206  could be made of a single pipe or of more or less than four main pipe sections. The pipe section  246  has a flange  254  used to fasten the exhaust pipe  206  to the rear of the rear cylinder  52  such that the end of the exhaust pipe  206  fluidly communicates with the exhaust port of the cylinder  52 . The end of the exhaust pipe  206  that fluidly communicates with the exhaust port of the cylinder  52  is disposed on a right side of the longitudinal centerline  134  ( FIG. 6 ). From the exhaust port, the pipe section  246  extends rearward and downward, then rearward and upward, and finally rearward and downward. As a result, the pipe section  246  passes over the cross-member  89  of the central frame portion  76 . The downstream end of the pipe section  246  is inserted into the upstream end of the pipe section  248 . A flange  256  on the downstream end of the pipe section  246  is fastened to a flange  258  on the upstream end of the pipe section  248  via spring-loaded fasteners  260 . From its upstream end, the pipe section  248  extends rearward and downward, then toward the right of the SSV  10 , then rearward toward the right of the SSV  10  and rearward toward the left of the SSV  10  in a generally U-shape, and finally toward the left of the SSV  10  across the longitudinal centerline  134 . The downstream end of the pipe section  248  is inserted over the upstream end of the pipe section  250 . A flange  262  on the downstream end of the pipe section  248  is fastened to a flange  264  on the upstream end of the pipe section  250  via spring-loaded fasteners  266 . A support  268  welded to the top of the pipe section  248  is used to connect the exhaust pipe  206  to a bracket (not shown) on the rear frame portion  80 . A rubber damper  270  disposed between the support  268  and the bracket reduces the transmission of vibrations between the frame  16  and the exhaust system  200 . From its upstream end, the pipe section  250  extends toward the left of the SSV  10 , upward and forward. The downstream end of the pipe section  250  has a flange  272  fastened to a flange  274  on the upstream end of the pipe section  252  via fasteners  276 . From its upstream end, the pipe section  252  extends forward, upward and toward the right of the SSV  10  into the expansion chamber  208 . As best seen in  FIG. 12 , the pipe section  252  then extends through the expansion chamber  208  and its downstream end is disposed and opens inside the collector  210 . The inlet  278  of the expansion chamber  208  (i.e. the aperture through which the pipe section  252  enter the expansion chamber  208 ) is disposed on a left side of the longitudinal centerline  134 . The portion of the pipe section  252  that is disposed inside the expansion chamber  208  has a plurality of apertures  280  fluidly communicating that portion of the pipe section  252  with the interior of the expansion chamber  208 . It is contemplated that there could be more or less apertures  280  and/or that the apertures  280  could be relatively bigger or smaller than illustrated. As such, the expansion chamber  208  in the present embodiment is a resonator. Sound absorbing material  282  is provided inside the expansion chamber  208  around the pipe section  252 . It is contemplated that the sound absorbing material  282  could be omitted. As can be seen, the exhaust pipe  206  is longer than the exhaust pipes  216 ,  218 . As can be seen in  FIGS. 2 to 5 , the expansion chamber  208  is disposed rearward of the engine  48  and the backrests  36 , forward of the rotation axes  136  of the rear wheels  22 , and in part below the cargo rack  40 . 
     The expansion chambers  204 ,  208  are adjacent to each other such that the expansion chamber  208  is disposed above and in contact with the expansion chamber  204 . It is contemplated that the expansion chambers  204 ,  208  could be spaced apart. As best seen in  FIG. 12 , the right ends (on the left in  FIG. 12 ) of the expansion chambers  204 ,  208  are received inside the left (on the right in  FIG. 12 ), upstream, end of the collector  210 . The left end of the collector  210  is welded around the expansion chambers  204 ,  208 . As can also be seen in  FIG. 12 , the ends of pipe sections  226 ,  252  point toward the center of the collector  210  and the outlet  284  of the collector  210 . The collector  210  is generally funnel-shaped and converges from its left end to its outlet  284  ( FIG. 12 ). A flange  286  disposed around the outlet  284  of the collector  210  is fastened to a flange  288  on the upstream end of the catalytic converter  212  via fasteners  290 . As can be seen in  FIGS. 2 to 5 , the collector  210  is disposed rearward of the engine  48  and the backrests  36 , forward of the rotation axes  136  of the rear wheels  22 , and in part below the cargo rack  40 . 
     As best seen in  FIG. 12 , the catalytic converter  212  is received inside the fitting  214  such that a majority of the catalytic converter is housed in the fitting  214 . As can be seen, the left end of the fitting  214  (on the right in  FIG. 12 ) fits tightly around the catalytic converter  212 . Similarly, the portion of the fitting  214  around the right end of the catalytic converter (on the left in  FIG. 12 ) fits tightly around the catalytic converter  212 . A space  292  is defined between the catalytic converter  212  and the fitting  214  between these tight fitting portions. As can also be seen in  FIG. 12 , the upstream ends of the exhaust pipes  216 ,  218  extend inside the chamber defined by the fitting  214  downstream of the catalytic converter  212 . 
     The exhaust pipe  216  extends through an opening disposed in the rear of the fitting  214 . From the fitting  214 , the exhaust pipe  216  extends rearward, upward and toward the left of the SSV  10 , then forward, downward and toward the left of the SSV  10 , and finally rearward and upward into the muffler  220 . The downstream end of the exhaust pipe  216  is received into the muffler  220 . It is contemplated that the exhaust pipe  216  could be made of multiple sections fastened together. The muffler  220  is connected to the exhaust pipe  216  by a clamp  294 . The muffler  220  is disposed rearward of the collector  210  on a left side of the longitudinal centerline  134 . As best seen in  FIG. 7 , the muffler  220  extends rearward and upward from its upstream end. The muffler  220  has a number of chambers, pipes and/or baffles defined therein. A support  296  welded to the top of the muffler  220  is used to connect the muffler  220  to a bracket  298  ( FIG. 3 ) connected to the member  132  on the rear frame portion  80 . A rubber damper  300  disposed between the support  296  and the bracket  298  reduces the transmission of vibrations between the frame  16  and the exhaust system  200 . A support  302  welded to the bottom of the muffler  220  forward of the support  296  is used to connect the muffler  220  to a bracket  304  ( FIG. 3 ) connected to the member  132  below the bracket  298 . A rubber damper  306  disposed between the support  302  and the bracket  304  reduces the transmission of vibrations between the frame  16  and the exhaust system  200 . As can be seen in  FIGS. 2 to 5 , the muffler  220  is disposed in part below the cargo rack  40 . 
     The exhaust pipe  218  extends through an opening disposed in the bottom of the fitting  214 . From the fitting  214 , the exhaust pipe  216  extends rearward and downward, and rearward and upward into the muffler  222 . The downstream end of the exhaust pipe  218  is received into the muffler  222 . It is contemplated that the exhaust pipe  218  could be made of multiple sections fastened together. The muffler  222  is connected to the exhaust pipe  216  by a clamp  308 . The muffler  222  is disposed rearward of the collector  210  on a right side of the longitudinal centerline  134 . As best seen in  FIG. 8 , the muffler  222  extends rearward and upward from its upstream end. The muffler  222  has a number of chambers, pipes and/or baffles defined therein. A support  310  welded to the top of the muffler  222  is used to connect the muffler  222  to the bracket  298  ( FIG. 3 ) connected to the member  132  on the rear frame portion  80 . A rubber damper  312  disposed between the support  310  and the bracket  298  reduces the transmission of vibrations between the frame  16  and the exhaust system  200 . A support  314  welded to the bottom of the muffler  222  forward of the support  310  is used to connect the muffler  222  to the bracket  304  ( FIG. 3 ) connected to the member  132 . A rubber damper  316  disposed between the support  310  and the bracket  304  reduces the transmission of vibrations between the frame  16  and the exhaust system  200 . As can be seen in  FIGS. 2 to 5 , the muffler  222  is disposed in part below the cargo rack  40 . 
     It is contemplated that the expansion chambers  204 ,  208 , which are resonators, could be replaced with another type of expansion chambers. In the exhaust system  200 ′ illustrated in  FIG. 13 , the expansion chambers  204 ,  208  have been replaced by expansion chambers  204 ′,  208 ′ respectively. The expansion chambers  204 ′,  208 ′ are mufflers. Although illustrated as each having a single chamber, it is contemplated that the expansion chambers  204 ′,  208 ′ could each contain multiple chambers, pipers and/or baffles. The pipe sections  226 ,  252  have been replaced with shorter pipe sections  226 ′,  252 ′. As a result, the pipe sections  226 ′,  252 ′ only extend partly inside their respective expansion chambers  204 ′,  208 ′. A pipe  318  connects the expansion chamber  204 ′ with the inside of the collector  210 . Similarly, a pipe  320  connects the expansion chamber  208 ′ with the inside of the collector  210 . The other elements of the exhaust system  200 ′ are the same as those of the exhaust system  200  and have been labeled in  FIG. 13  with the same reference numerals. These elements will not be described again herein. 
     Each main pipe section  224 ,  226 ,  246 ,  248 ,  250 ,  252 ,  226 ′,  252 ′ and each exhaust pipe  216 ,  218  is made of multiple pipe sections welded or otherwise connected together. For simplicity and clarity, these sections were not described. It is contemplated that each main pipe section  224 ,  226 ,  246 ,  248 ,  250 ,  252 ,  226 ′,  252 ′ and each exhaust pipe  216 ,  218  could also be made of a single bent pipe. 
     Modifications and improvements to the above-described embodiments of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.