DESC:FIELD OF INVENTION
[0001] The subject matter as described herein, relates generally to an exhaust system and more particularly, to an exhaust muffler for a step-through type two-wheeled vehicle.
BACKGROUND OF INVENTION
[0002] In general, the exhaust muffler in a two-wheeled vehicle is on the right side of the vehicle (decided with respect to a rider sitting on the vehicle). For tires with larger width, a larger width rim is required. Furthermore, in order to use wider tire, an outward direction shift of muffler from tire is required, which will further reduce banking angle of muffler during cornering. In such a vehicle, due to the rim and the tire being of higher width, during disassembly and replacing of the rear wheel, the wheel interferes with the exhaust muffler, further translating into an assembly related issues. Hence, in the current vehicle layout, wherein the exhaust muffler is on the sides of the vehicle, for removing and replacing wheel, it is desirable that first the muffler be removed. This unnecessary removal of exhaust muffler for replacing the rear wheel further leads to an increased servicing time. Moreover, in cases when vehicle falls, a muffler on sides of the vehicles is prone to breakage and thus may lead to high replacement costs.
[0003] Typically, an exhaust muffler helps to provide a passage for expulsion of burnt and unburnt gases from engine to the outer atmosphere. Exhaust mufflers have a single tail pipe, which releases the exhaust gases to the environment. An inefficient expulsion of exhaust gases may lead to building up of backpressure on the exhaust port, which may further lead to an inefficient combustion of fuel inside the cylinder. Generally, a means to create negative pressure outside the muffler outlet helps expulsion of the exhaust gases from the muffler.
SUMMARY OF THE INVENTION
[0004] To obviate the problems associated with locating of exhaust gases on the sides of the vehicle, the current invention is more particularly applicable to step through vehicles wherein the gap between the rear wheel and the exhaust muffler is not sufficient for easy removal of the rear wheel without removing the exhaust muffler. To eliminate the constraint of involvement of an additional step of removing the existing muffler for replacing rear wheel and for maintaining the banking angle for mufflers during cornering, in step through two wheeled vehicles, the current invention proposes an exhaust muffler located below the floorboard. This new location under the floorboard additionally provides a larger space for the exhaust muffler and tool usage freedom for replacement of the rear wheel.
[0005] The disclosed exhaust muffler further comprises of plurality of expansion chambers, which serve the dual purpose of cooling the hot exhaust gases and at the same time, attenuating the engine noise. According to the present invention, the area beneath the floorboard is utilized for locating the expansion chamber. The exhaust muffler according to the present invention further comprises of a tail pipe on atleast one expansion chamber.
BRIEF DESCRIPTION OF DRAWINGS
[0006] Figure 1illustrates a typical two-wheeler.
[0007] Figure 2illustrates top view of a typical two-wheeler showing the exhaust muffler on the right side on the rear end as per the prior art.
[0008] Figure 3 illustrates the rear view of the rear wheel and exhaust muffler assembly as per the prior art.
[0009] Figure 4 illustrates top view of two-wheeler showing the exhaust muffler on the right side on the rear end as per the current invention.
[00010] Figure 5 illustrates a perspective view of the insulation mechanism in-between the exhaust muffler and the rider foot.
[00011] Figure 6 illustrates the cross sectional view of the vehicle showing the mounting arrangement of the exhaust muffler along with the floorboard.
DETAILED DESCRIPTION OF THE INVENTION
[00012] To facilitate dis-assembly and maintenance of the rear wheel, the present invention describes a floorboard mounted on a down tube frame and disposed under the floorboard of a step through vehicle. The present invention eliminates the constraint of an additional step of removing the existing muffler for replacing rear wheel. The present invention also solves the issues of banking angle for mufflers during cornering. The exhaust muffler location under the floorboard further provides an additional advantage of increased expansion chamber volumes for the exhaust mufflers. The disclosed exhaust muffler layout at the same time provides a larger exhaust muffler volume with expansion chambers on both sides of the down tube.
[00013] The internal combustion engine according to present invention comprises of an intake system and an exhaust system. The intake system further comprises of an air filter and a carburetor. A fuel tank supplies fuel to the carburetor. The exhaust system comprises of a first end of an exhaust pipe connected to an exhaust port of the internal combustion engine. A second end of the exhaust pipe connects to a first expansion chamber, which further connects to a plurality of expansion chambers. The plurality of expansion chambers has atleast one tail pipe through the exhaust gases leave the exhaust system.
[00014] The first expansion chamber acts as an inlet chamber for the exhaust system. The first expansion chamber along with the other plurality of expansion chambers is preferably perforated. In yet another embodiment of the present invention, the first expansion chamber and the plurality of expansion chambers comprises baffle section that comprises of plurality of holes to allow a fraction of exhaust gases to pass through the catalytic convertor. The holes within the baffles also functions to attenuate the engine noise.
[00015] The location of muffler under floorboard and in front of the engine in a step through vehicle requires the muffler body manufactured as a single or split type design based on the layout constraints of the vehicle. The expansion chambers are preferably vertically opening with horizontal split. The two split portions joined to each other using an intermediate resilient member. The floorboard is attached to the vehicle frame using plurality of mounting brackets. The tail pipes on plurality of expansion chambers are oriented to expel the exhaust gases in rearward direction away from the central longitudinal axis.
[00016] A first side of the central longitudinal axis accommodates the first expansion chamber while the second expansion chamber is on the second side of the central longitudinal axis. In yet another embodiment of the present invention, the first expansion chamber substantially lies along the central longitudinal axis. An optional second expansion chamber according to the present invention in this second embodiment is located with an offset with respect to the central longitudinal axis.
[00017] Figure 1 illustrates a typical two-wheeler. Figure 1 shows a typical two-wheeled vehicle 1 with a rear wheel 2, engine 3, air filter 4, front wheel 5, floorboard6, utility box 7, side panel 9, front shock absorber 10, rear shock absorber 11, grab rail 12, tail lamp 13, rider seat 14 and cylinder head portion 15. The direction of arrow “F” shows the front direction of the vehicle and direction of arrow “R” shows the rear direction of the vehicle. The combustion of fuel inside cylinder of the engine generates a large amount of heat energy. An exhaust muffler provides passage for burnt fuel and exhaust gases to expel them from the engine. The exhaust muffler, in such a typical step through type two-wheeled vehicle is located on the right side.
[00018] Figure 2 illustrates top view of a typical step through type two-wheeler showing the exhaust muffler on the right side on the rear end as per the prior art. Figure 2 illustrates the rear wheel 2, front wheel 5, utility box 7, down tube 20, radiator 21 (optional), side tube RH 22, side tube LH 23, longitudinal axis 25, radiator mountings 26 (optional), vehicle front F and vehicle rear R. Figure 2 further shows rear wheel 2, rear wheel- exhaust muffler gap 28, and exhaust muffler 29. The directions in Figure 2 are labelled with respect to a rider sitting on the rider seat of the vehicle 1. As illustrated in Figure 2, the rear wheel- exhaust muffler gap 28 determines the serviceability of the rear wheel 2. A lesser rear wheel- exhaust muffler gap 28 will lead to interference of the rear wheel 2 with the exhaust muffler 29 during dis assembly and re-assembly.
[00019] Figure 3 shows rear wheel 2, rear wheel- exhaust muffler gap 28, and exhaust muffler 29. Figure 3 further illustrates the perspective rear view of the step through vehicle according to the prior art. The rear wheel 2 and exhaust muffler 29 assembly as per the prior art is illustrated. Figure 3 illustrates possible interference of the rear wheel 2 with the exhaust muffler 29.
[00020] Figure 4 illustrates top view of two-wheeler showing the exhaust muffler on the right side on the rear end as per the current invention. Figure 4 shows exhaust muffler 41, exhaust pipe 42, and exhaust port 43. The exhaust pipe 42 of the exhaust muffler 41 is connected to the exhaust port 43 of the engine 3. As would be illustrated and explained in a more detail, the exhaust muffler 41 is located under a floorboard of the step through type vehicle. The central longitudinal axis 5 divides the vehicle floorboard 6 into two portions namely a first portion 44 and a second portion 45. The first portion 44 and second portion 45 referred herein are located under/below the floorboard.
[00021] Figure 5 illustrates a perspective view of floorboard and the exhaust muffler arrangement according to the current invention. The floorboard also functions as an insulation mechanism in-between the exhaust muffler and the rider foot. Figure 5 shows exhaust pipe 42, floor board LH 51, floor board RH 52, exhaust muffler mounting RH 53A, exhaust muffler mounting RH 53B, exhaust muffler mounting LH 53C, exhaust muffler mounting LH 53D, tail pipe LH 54, tail pipe RH 55, exhaust muffler bottom body 56 and exhaust muffler top body 57. The floorboard LH 51, floorboard RH 52 provides insulation to the rider feet from the exhaust muffler body 41. The exhaust muffler bottom body 56 and exhaust muffler top body 57 forms two expansion chambers mainly a first expansion chamber 58 and a second expansion chamber 59. As illustrated, the exhaust gases from the engine 3 enter the exhaust pipe 42. The exhaust gases expand inside the chamber formed out of the exhaust muffler bottom body 56 and exhaust muffler top body 57 viz. mainly the first expansion chamber 58 and the second expansion chamber 59 and exits the exhaust muffler body 41 through the tail pipe LH 54, tail pipe RH 55. The exit way for the exhaust gases through atleast one of the tail pipe LH 54, tail pipe RH 55 expels the exhaust gases rearwardly direction away from the central longitudinal axis 5.
[00022] The first expansion chamber 58 and the second expansion chamber 59 are fastened to a mounting location on the vehicle frame using plurality of mounting brackets mainly the exhaust muffler mounting RH 53A, exhaust muffler mounting RH 53B, exhaust muffler mounting LH 53C and exhaust muffler mounting LH 53D.
[00023] Figure 6 illustrates the cross sectional view of the exhaust muffler body showing the mounting arrangement of the exhaust muffler along with the floorboard. The illustrated cross section is taken along the axis AA’ (Shown in Figure 4). Figure 6 shows exhaust muffler bottom body 56, exhaust muffler top body 57, down tube 20, exhaust pipe 42, tail pipe RH 55, tail pipe LH 54, exhaust muffler mounting bracket LH 61A, exhaust muffler mounting bracket RH 61B, floor board mounting bracket LH 62A, floor board mounting bracket RH 62B, mounting pin LH 63A, mounting pin RH 63B, floor board 64 and LH tube floor board 65A. The first expansion chamber 58 and second expansion chamber 59 is disposed below the floorboard 6.
[00024] Exhaust muffler bottom body 56 and exhaust muffler top body 57 forms two expansion chambers namely the exhaust muffler body LH 71 which houses of the first expansion chamber 58. The exhaust muffler body RH 72 which lies on other side of the central longitudinal axis 5 houses of the second expansion chamber 59. The exhaust muffler body LH 71 houses the first expansion chamber and the exhaust muffler body RH 72 houses the second expansion chamber. The first expansion chamber, which is housed inside the exhaust muffler body LH 71, houses the catalytic convertor. The second expansion chamber, which is also the exhaust muffler body RH 72, houses the outwardly protruding tail pipe 55. The exhaust muffler body LH 71 and exhaust muffler body RH 72 together forms the exhaust muffler body 74.
[00025] The floor board 64 (6) and the first and second expansion chambers (58,59) formed out of the exhaust muffler bottom body 56 and exhaust muffler top body 57 is fastened to the vehicle frame through mounting pin LH 63A on left side and through mounting pin RH 63B on the right side. The mounting pin LH 63A and mounting pin RH 63B are further rigidly connected to a tube floorboard (65A, 65B), the tube floorboard (65A, 65B) being part of vehicular frame structure. The exhaust muffler top body 57 is rigidly fastened to the mounting pin LH 63A using the exhaust muffler mounting bracket LH 61A on left side. Similarly, the exhaust muffler top body 57 is rigidly fastened to the mounting pin RH 63B using the exhaust muffler mounting bracket RH 61B on right side of the central longitudinal axis 6.
[00026] Figure 7 shows the first expansion chamber 71 and the second expansion chamber 72 connected to each other through a connecting pipe 73. The first expansion chamber, which is also the exhaust muffler body LH 71, houses the catalytic convertor. The second expansion chamber that is also the exhaust muffler body RH 72 houses the outwardly protruding tail pipe 55. The exhaust gases first enter the first expansion chamber 71, are treated and then travel to the second expansion chamber from where it finally exits through the tail pipe 55.
[00027] The vehicle has a frame structure with a head pipe 33, a rearwardly downward down tube 20, a substantially horizontal frame member 34 and a pair of frame structure 22, 23 branching rearwardly upwards on each side of the substantially horizontal frame member 34. The floorboard 6 is fastened from top to the substantially horizontal frame member 34. The engine 3 is located rearwardly to the horizontal frame member 34 and said floorboard 6 lies in between the rearwardly upward frame structures 22, 23. The exhaust muffler body 74 is mounted below the horizontal frame member 34 below the floorboard 6 in front of the engine 3 on atleast one side of the down tube 20.
[00028] The absence of the exhaust muffler 41 on the right side of the step through vehicle 1 provides more degree of freedom for assembly and replacement of rear wheel 2 during servicing of the vehicle without need of removing the exhaust muffler 41.
,CLAIMS:We claim:
1. A step through vehicle (1) comprising:
a vehicle frame structure with a head pipe (33) forming front portion of the vehicle frame structure;
a rearwardly downward down tube (20) extending rearward with respect to said head pipe (33);
a substantially horizontal frame member (34) and a pair of frame structure (22,23) branching rearwardly upwards on each side of the substantially horizontal frame member (34);
a floorboard (6,64) fastened from top to said substantially horizontal frame member (34);
an engine located rearwardly to said horizontal frame member (34) and said floorboard (6) lying in between said rearwardly upward frame structures (22,23);
characterized in that:
an exhaust muffler body (74) is mounted on said horizontal frame member (34) with the exhaust muffler body (74) disposed below said floor board (6) in vehicular front direction relative to the engine (3) on atleast one side of said down tube (20).
2. The step through vehicle as claimed in claim 1 wherein the exhaust muffler body (74) further comprises of expansion chambers (58,59) disposed below the floor board (6) on atleast one side of the down tube (20).
3. The step through vehicle as claimed in claim 1 wherein the expansion chambers (58, 59) are housed within an exhaust muffler body LH 71 and an exhaust muffler body RH 72.
4. The step through vehicle as claimed in claim 1 wherein at least one of the expansion chambers (58, 59) houses a catalytic convertor.
5. The step through vehicle as claimed in claim 1 wherein atleast one of the expansion chambers (58, 59) accommodates atleast one tail pipe (54, 55).
6. The step through vehicle as claimed in claim 1 wherein atleast one of the expansion chambers (58, 59) is covered through insulating floorboard LH 51 and floorboard RH 52.
7. The step through vehicle as claimed in claim 1 wherein atleast one of the expansion chambers (58, 59) is disposed on either side of the central longitudinal axis (6).
8. The step through vehicle as claimed in claim 1 wherein atleast one of the expansion chambers (58, 59) is disposed on either side of the central longitudinal axis (6).
9. The step through vehicle as claimed in claim 1 wherein atleast one of the expansion chambers (58, 59) accommodating tail pipe (54, 55) emits the exhaust gases rearwardly away from said central longitudinal axis (6)