Title of Invention

A CATALYST ARRANGEMENT STRUCTURE OF MOTORCYCLE

Abstract [Problem] To provide the catalyst arrangement structure of a motorcycle which arranges a catalyst chamber in a compact manner- [Means for Resolution] Out of exhaust passages 62, 63 corresponding to an inlet and an outlet of a catalyst chamber 80, an axis of a catalyst 85 is aligned with the passage direction of one exhaust passage 63, and another exhaust passage 62 is opened within a width in the length direction of the catalyst 85, [Selected Drawing] Fig, 3
Full Text

[Designation of Document] Specification
[Title of the Invention] A CATALYST ARRANGEMENT STRUCTURE OF A MOTORCYCLE
[Technical Field] [0001]
The present invention relates to the catalyst arrangement structure of a motorcycle which arranges a catalyst chamber in a middle portion of an exhaust pipe which connects an exhaust port and a muffler.
[Background Art] [0002]
In general, there has been known a motorcycle which forms a catalyst chamber on a middle portion of an exhaust pipe which connects an exhaust pipe and a muffler. In this type of the motorcycle, to impart a sufficient purification performance to the catalyst in the catalyst chamber, it is desirable to arrange the catalyst at a center position of the flow of an exhaust gas thus allowing the exhaust gas and the catalyst to be in contact with each other for a long time. However, when the catalyst is arranged at the center position of the flow of the exhaust gas, a flow speed of the exhaust gas is higher at the center position of the flow of the exhaust gas than the peripheral portion in the catalyst chamber and hence, the flow speed of the exhaust gas which flows into the catalyst becomes excessively high at the center position in the catalyst chamber

whereby a purification time for the exhaust gas is shortened.
[0003]
To prevent this phenomenon, conventionally, the catalyst arrangement structure in which a large-capacity catalyst chamber is connected to the middle portion of the exhaust pipe which has an outlet and an inlet and linearly extends, the catalyst is arranged in the catalyst chamber with an axis thereof displaced from an axis of the catalyst chamber, a flow speed of the exhaust gas which flows into the catalyst from the inlet is once lowered in the chamber and, then, the exhaust gas is introduced into the catalyst and is sufficiently purified and, thereafter, the exhaust gas is discharged from an outlet of the chamber has been proposed (see patent document 1, for example).
[Patent Document 1] JP-A-2002-317627 [Disclosure of the Invention] [Problems that the Invention is to Solve]
[0004]
However, in the above-mentioned conventional structure, an axis of the exhaust pipe and the axis of the catalyst are displaced from each other and hence, the catalyst chamber becomes large-sized. Further, the catalyst chamber is arranged in a straight portion of the exhaust pipe and hence, the exhaust pipe is elongated thus preventing the compact arrangement of the catalyst chamber.

Accordingly, it is an object of the invention to provide the catalyst arrangement structure of a motorcycle which arranges a catalyst chamber in a compact manner. [Means for solving the problem]
[0006]
To overcome the above-mentioned drawbacks, the invention provides the catalyst arrangement structure of a motorcycle which arranges a catalyst chamber on a middle portion of an exhaust pipe which connects an exhaust port of a cylinder head and a muffler, wherein out of exhaust passages corresponding to an inlet and an outlet of the catalyst chamber, an axis of a catalyst is aligned with the passage direction of one exhaust passage, and another exhaust passage is opened within a width in the length direction of the catalyst.
According to the invention, out of the exhaust ports corresponding to the inlet and the outlet of the catalyst chamber, the axis of the catalyst is aligned with the passage direction of one exhaust passage, and another exhaust passage is opened within the width in the length direction of the catalyst and hence, the catalyst chamber can be connected to a bent pipe which constitutes the exhaust pipe thus realizing the compact arrangement of the catalyst chamber.
[0007]
In the above-mentioned constitution, it is preferable

to arrange the catalyst along an axis of one exhaust passage, and to make an opening formed in a side surface of the catalyst chamber which constitutes an opening of another exhaust passage face a side surface of the catalyst. Due to such a constitution, the catalyst is arranged along the axis of one exhaust passage and hence, the catalyst chamber can be miniaturized. Further, the opening formed in the side surface of the catalyst chamber faces the side surface of the catalyst and hence, a flow speed of the exhaust gas which enters the inside of the catalyst from the surrounding of the catalyst and passes through the catalyst can be suppressed.
[0008]
Further, in the above-mentioned constitution, the opening formed in the side surface of the catalyst chamber may preferably be an opening which is directed to the exhaust port. Due to such a constitution, a temperature of the catalyst can easily arrive at an activation temperature due to the heat of the high-temperature exhaust gas from the exhaust port and, at the same time, water from the outside hardly intrudes into the opening formed in the side surface thus preventing the catalyst from being splashed with water.
[0009]
Further, in the above-mentioned constitution, the catalyst may preferably be held in a recessed portion of the catalyst chamber. Due to such a constitution, an additional

fixing member for fixing the catalyst becomes unnecessary and hence, a manufacturing cost can be reduced.
[0010]
Further, in the above-mentioned constitution, another exhaust passage may preferably communicate with the catalyst chamber at a position offset from a catalyst in the catalyst chamber. Due to such a constitution, it is possible to allow the exhaust gas to pass through the catalyst after lowering the flow speed of the exhaust gas in the inside of the catalyst chamber thus avoiding the generation of vibrations of the catalyst or the like.
[0011]
Further, in the above-mentioned constitution, a bulging portion which bulges toward an engine side along a cylinder block of the engine and a crankcase may preferably be formed on the catalyst chamber, and another exhaust passage may preferably communicate with the bulging portion. Due to such a constitution, it is possible to arrange the bulging portion in a dead space defined between the cylinder block and the crankcase thus enhancing a layout efficiency of the bulging portion.
[0012]
Further, in the above-mentioned constitution, another exhaust passage may preferably be formed into a shape such that the exhaust passage wraps around the catalyst chamber and

communicates with a side surface of the catalyst chamber. Due to such a constitution, it is possible to allow the exhaust gas to flow smoothly.
[0013]
Further, in the above-mentioned constitution, the catalyst chamber may preferably be arranged below a cylinder of a horizontal engine. Due to such a constitution, by arranging the catalyst chamber below the cylinder of the horizontal engine, it is possible to prevent the occurrence of a situation in which a lowermost ground height of the vehicle is lowered due to the catalyst chamber or the occurrence of a situation in which a bank angle of the vehicle is limited. [Advantage of the Invention]
[0014]
According to the invention, out of the exhaust passage corresponding to the inlet and the outlet of the catalyst chamber, the axis of the catalyst is aligned with the passage direction of one exhaust passage, and another exhaust passage is opened within the width in the length direction of the catalyst and hence, the catalyst chamber can be connected to a bent pipe which constitutes the exhaust pipe thus realizing the compact arrangement of the catalyst chamber.
Further, by arranging the catalyst along the axis of one exhaust passage, and by allowing an opening formed in a side surface of the catalyst chamber which constitutes an opening

of another exhaust passage to face a side surface of the catalyst^ the catalyst chamber can be miniaturized, and at the same time, a flow speed of the exhaust gas which enters the inside of the catalyst from the surrounding of the catalyst and passes through the catalyst can be suppressed.
Further, the opening formed in the side surface of the catalyst chamber is formed of the opening which is directed to the exhaust port and hence, a temperature of the catalyst can easily reach an activation temperature due to the heat of the high-temperature exhaust gas and, at the same time, water from the outside hardly intrudes into the opening formed in the side surface thus preventing the catalyst from being splashed with water.
Further, the catalyst is held in the recessed portion of the catalyst chamber and hence, an additional fixing member for fixing the catalyst is unnecessary whereby a manufacturing cost can be reduced.
[0015]
Further, by allowing another exhaust passage to communicate with the catalyst chamber at a position offset from a catalyst in the catalyst chamber, it is possible to allow the exhaust gas to pass through the catalyst after lowering the flow speed of the exhaust gas in the inside of the catalyst chamber thus avoiding the generation of vibrations of the catalyst and the like.

Further, by forming the bulging portion which bulges toward the engine side along the cylinder block and the crankcase of the engine on the catalyst chamber and by allowing another exhaust passage to communicate with the bulging portion, it is possible to arrange the bulging portion in the dead space defined between the cylinder block and the crankcase.
Further, by forming another exhaust passage into a shape such that another exhaust pipe wraps around the catalyst chamber and communicates with a side surface of the catalyst chamber, it is possible to allow the exhaust gas to flow smoothly.
Still further, the catalyst chamber is arranged below the cylinder of the horizontal engine and hence, it is possible to prevent the occurrence of a situation in which a lowermost ground height of the vehicle is lowered due to the catalyst chamber or the occurrence of a situation in which a bank angle of the vehicle is limited, [Best Mode for Carrying out the Invention]
[0016]
One embodiment of the invention is explained in conjunction with attached drawings hereinafter. Here, in explanations, descriptions of the directions such as backward and forward, right and left or up and down indicate the directions with respect to a vehicle body.

(First einbodiment)
Fig. 1 shows a side view of a motorcycle according to a first embodiment.
This motorcycle 1 includes a vehicle-body frame 2, a pair of right and left front forks 3 which is rotatably supported on a head pipe 20 mounted on a front end of the vehicle-body frame 2, a steering handle bar 4 which is mounted on upper end portions of the front forks 3, a front wheel 5 which is rotatably supported on lower end portions of the front forks 3, an engine 6 which is supported on the vehicle-body frame 2 substantially at the center of the vehicle body, a rear fork 7 which is supported on the vehicle-body frame 2 in a vertically rocking manner, a rear wheel 8 which is rotatably supported on a rear end portion of the rear fork 7, a pair of right and left rear cushions 9 which is arranged between a rear portion of a rear fork 7 and the vehicle-body frame 2, a fuel tank 10 which is supported on a rear portion above the vehicle-body frame 2, a storage box 11 which is supported on the vehicle-body frame 2, a seat 12 which is arranged on the storage box 11, a grab rail 13 which is arranged behind the seat 12, and a vehicle-body cover 14 made of a synthetic resin which covers the vehicle-body frame 2.
[0017]
The vehicle-body cover 14 includes a front cover 14A which covers a front portion of the vehicle-body frame 2, a

pair of right and left leg shields 14B which covers front portions of legs of a rider, a pair of right and left front-side covers 14C which covers a front portion of the engine 6, a main-frame top cover 14D which connects upper portions of the front-side covers 14C, a pair of right and left rear-side covers 14E which covers a lower portion of the storage box 11, and a rear-body cover 14F which covers remaining portions of the storage box 11 and the fuel tank 10 from both sides. Here, the leg shields 14B, the front-side covers 14C and the main-frame top cover 14D are integrally formed with each other. Further, a head lamp 15 and blinkers 16 are arranged on the front cover 14A, a tail lamp 17 is arranged at a rear end of the rear-body cover 14F, and a front fender 18 which covers the front wheel 5 is arranged on the front fork 3.
[0018]
The vehicle-body frame 2 includes a head pipe 20, a main frame 21 which extends in the rearward and downward direction from the head pipe 20 at the center of the vehicle body, a pair of right and left rear frames 22 which is connected to rear portions of the main frame 22 and extends in the rearward and oblique upward direction, a pair of right and left pivot plates 23 which is joined to front portions of the respective rear frames 22, and a pair of support frames 24 which connects middle portions of the respective pivot plates 23 and the respective rear frames 22. The storage box 11, the fuel tank 10, the

vehicle-body cover 14 and the like are mounted on the rear frame 22, and the seat 12 which can cover the storage box 11 and the fuel tank 10 from above is mounted on the rear frame 22 in an openable and closable manner. Further, upper portions of the rear cushions 9 are connected to a rear portion of the rear frame 22 by way of rear-cushion brackets 22A at a rear portion of the rear frame 22.
[0019]
To the pivot plate 23, the rear fork 7 which supports the rear wheel 8, a main stand 30 for parking the vehicle body in an upright state, and a side stand 31 for parking the vehicle body in an inclined stance are connected. The rear fork 7 has a front end thereof rotatably supported on both pivot plates 23 by way of a pivot bolt 7A, and is supported in a vertically rocking manner using the pivot shaft 7A as a fulcrum.
[0020]
The main stand-30 has one end thereof rotatably supported on both pivot plates 23 by way of a pivot shaft 34 which passes through both pivot plates 23 at a position below the pivot bolt 7A. The main stand 30, as shown in Fig. 2, is integrally constituted of an inserting portion 30A in which the pivot shaft 34 passes through, a pair of right and left leg portions 30B which extend from the inserting portion 30A, a stopper portion 30C which extends to a vehicle body center side from one leg portion 30B (the right leg portion in this embodiment) , and

a leg rest portion 30D which extends from the left leg portion 30B. Using the pivot shaft 34 as a fulcrum, the main stand 30 is rotatable from a position at which the left leg portion 30B is directed rearwardly with respect to the vehicle body shown in Fig. 1 (corresponding to a stored position) to a position at which the left leg portion 30B is directed downwardly with respect to the vehicle body (corresponding to a vehicle stop position).
[0021]
The side stand 31 is rotatably supported on the left pivot plate 23 using a bolt 35. Fig. 1 shows a state in which the side stand 31 is projected. Here, in Fig, 1 and Fig. 2, a pair of right and left main steps 36 on which a rider who sits on a front portion of a seat 12 places his/her leg, a change pedal 37 and a brake pedal 38 which the rider manipulates, and a pair of right and left pillion steps 39 on which a pillion who sits on a rear portion of the seat 12 places his/her leg are shown. A pillion step 39 is shown in a state that the pillion step 39 is folded to the vehicle body side.
[0022]
On both sides of middle portions of the main frames 21,
as shown in Fig. 1, an engine hanger 40 is mounted. The engine
6 is supported by way of the engine hanger 40 and the pivot
plate 23. The engine 6 is a horizontal single cylinder engine
(horizontal engine) which includes a crankcase 41, a cylinder

block 42 which is connected to a front portion of the crankcase 41, a cylinder head 43 which is connected to a front portion of the cylinder block 42, and a head cover 44 which is connected to a front portion of the cylinder head 43, wherein a cylinder in the inside of the cylinder block 42 is horizontally arranged.
[0023]
With respect to this cylinder block 42, a piston is housed in the inside of a cylinder 42A in a reciprocating manner. In the crankcase 41, a crankshaft which is connected with the above-mentioned piston by way of a connecting rod, a centrifugal clutch mechanism and a transmission on which the output shaft 6A of engine 6 and the kick pedal 6B are pivotally supported and, at the same time, constitute a power transmission mechanism between the crankshaft and the output shaft 6A and the like are housed. The transmission of power to the rear wheel 8 from the above-mentioned output 6A is performed by way of a chain power transmission mechanism 50. That is, the power of the engine 6 is transmitted to the rear wheel 8 by way of sprocket wheels 51, 52 which are respectively mounted on the above-mentioned output shaft 6A and the rear wheel 8 and the drive chain 53 which is wound around these sprocket wheels 51, 52.
[0024]
The cylinder head 43 includes an intake port 43A which opens in an upper surface of the cylinder head 43 while

communicating with the inside of the cylinder 42A, and an exhaust port 43B which opens in a lower surface of the cylinder head 4 3 by communicating with the inside of the cylinder head 42A. Between the cylinder head 43 and the main frames 21, a throttle body 55 and an air cleaner 56 which constitute an intake system of the engine 6 are arranged. The throttle body 55 is connected to the intake port 43A and the air cleaner 56 is connected to the front portion (an upstream side of the throttle body 55) . Further, an exhaust unit 60 which constitutes an exhaust system of the engine 6 is connected to the exhaust port 43B.
[0025]
The exhaust unit 60, as shown in Fig. 2, includes an exhaust pipe 61, a catalyst chamber 80 and a muffler 90, wherein the exhaust pipe 61 constitutes an exhaust passage which connects the exhaust port 43B and the muffler 90. Fig. 3(A) is a top plan view showing the exhaust pipe 61 and the catalyst chamber 80 and. Fig. 3(B) is a side view showing the exhaust pipe 61 and the catalyst chamber 80.
[0026]
The exhaust pipe 61, as shown in Fig. 3 (A) and Fig. 3 (B) , includes a front exhaust pipe 62 which is formed of a bent pipe and a rear exhaust pipe 63 which extends substantially horizontally. With respect to the front exhaust pipe 62, as shown in Fig. 4 and Fig. 5, a diameter of a distal end of a

bent metal pipe 62A is enlarged, a joint 64 is provided more inside than the enlarged diameter portion, and a collar 65 is mounted on the enlarged diameter portion. The front exhaust pipe 62 is connected to the cylinder head 43 by bringing the collar 65 into pressure contact with the cylinder head 43 with a gasket not shown in the drawing sandwiched therebetween and fastening the joint 64 to the cylinder head 43 using bolts thus allowing the front exhaust pipe 62 to be communicated with the exhaust port 43B. As shown in Fig. 2 and Fig. 3(B), to house the front exhaust pipe 62 within a width of the engine 6, the front exhaust pipe 62 extends from the exhaust port 43B, is bent in the vicinity of the cylinder head 43, and has a rear end thereof opened toward a vehicle body side (right side) below the cylinder head 43, and connects the catalyst chamber 80 to an opening end. With respect to the rear exhaust pipe 63, a bent portion 63A which bends behind the catalyst chamber 80 is formed. Due to such a bent portion 63A, the rear exhaust pipe 63 can be arranged while avoiding a drain bolt 6D which is fastened below the crankcase 41 of the engine 6.
[0027]
The catalyst chamber 80, as shown in Fig. 3(A) and Fig. 3(B), includes a cylindrical case 81 having an approximately cylindrical shape. The cylindrical case 81 is formed by joining an upper case 81A and a lower case 81B which are split in two vertically by welding. The cylindrical case 81 includes

a side-surface opening portion 82 which opens in a projecting manner from a side surface of the cylindrical case 81. The side-surface opening portion 82 corresponds to one exhaust passage of an inlet and an outlet of the catalyst chamber 80, a rear end of the exhaust pipe 62 is inserted into and joined to the side-surface opening portion 82 by welding. In such a state, the side-surface opening portion 82 forms an opening directed to the exhaust port 43B of the engine 6.
[0028]
On a rear end portion of the cylindrical case 81, an opening port 83 which opens while reducing a diameter thereof is formed. The opening portion 83 corresponds to another exhaust passage of the inlet and the outlet port of the catalyst chamber 80, is fixed to a small-diameter portion of a guide cap 84 having an approximately conical shape from the inside of the case, a catalyst 85 is fixed to a large-diameter portion of the guide cap 84, and the rear exhaust pipe 63 is inserted and joined by welding to the inside of the small-diameter portion of the guide cap 84. Since the catalyst 85 and the rear exhaust pipe 63 are coaxially arranged by way of the guide gap 84, the catalyst 85 is arranged along an axis of the exhaust passage in the rear exhaust pipe 63.
Further, an upper surface and a lower surface (the upper case 81A and the lower case 81B) of the cylindrical case 81 are partially depressed to the inside of the cylindrical case

81 thus forming a pair of upper and lower recessed portions 81C, 81D integrally. These recessed portions 81C, 81D sandwich the catalyst 85 from above and below thus holding the catalyst 85. [0029] The catalyst 85 eliminates hydrocarbon, carbon monoxide, nitrogen oxide and the like contained in the exhaust gas by an oxidation reaction or a reduction reaction. Such a catalyst 85 adopts a honeycomb three-dimensional catalyst which is constituted by applying platinum, palladium, rhodium or the like to a porous honeycomb structural body. The catalyst 85 is held in the cylindrical case 81 with a predetermined gap between the catalyst 85 and inner walls (a front wall and a side wall) of the cylindrical case 81, and the above-mentioned side-surface opening portion 82 is opened within a width of the catalyst 85 in the length direction of the catalyst 85 and is formed at a position where the opening portion 82 faces a side surface of the catalyst 85.
Accordingly, the exhaust gas which is discharged from the engine 6 enters the inside of the catalyst chamber 80 after passing through the above-mentioned exhaust pipe 62 and, as indicated by an arrow in Fig. 3(A) , flows toward the side surface of the catalyst 85. Thereafter, the exhaust gas enters the inside of the catalyst 85 after passing through the gap around the catalyst 85. Here, hydrocarbon, carbon monoxide,

nitrogen oxide and the like are removed by the oxidation reaction and the reduction reaction and, thereafter, the exhaust gas passes through the guide cap 84 and flows into the inside of the rear exhaust pipe 63. Here, in place of the honeycomb three-dimensional catalyst, a heat tube which carries platinum, palladium, rhodium or the like on a punching pipe may be used as the catalyst 85.
[0030]
According to the constitution of this embodiment, as described above, to the side-surface opening portion 82 of the catalyst chamber 80, the front exhaust pipe 62 constituting the bent pipe which is bent from the exhaust port 43B and opens on the side of the vehicle body below the cylinder head 43 is connected and hence, the catalyst chamber 80 is, as shown in Fig. 1, arranged in the vicinity of a position right below the cylinder 42A. Accordingly, the catalyst chamber 80 can be arranged in a vacant space below the cylinder head 43 and the cylinder block 42 thus preventing the occurrence of the situation in which a lowermost ground height of the vehicle is lowered due to the catalyst chamber 8 0 or the occurrence of the situation in which the bank angle of the vehicle is limited due to the catalyst chamber 80.
[0031]
The rear exhaust pipe 63 extends rearwardly after passing below the engine 6 and the center of the vehicle body and,

thereafter, is bent obliquely and upwardly with respect to the vehicle body at a rear portion of the engine 6 and, thereafter, has a rear end portion thereof connected with a muffler 90. In this case, the rear exhaust pipe 63 passes below the engine 6 within a width of the engine 6 and has the rear end thereof connected to the muffler 90 and hence, the bending of the rear exhaust pipe 63 is small whereby the exhaust resistance can be lowered. At the same time, it is possible to prevent the occurrence of the situation in which the lowermost ground height of the vehicle is lowered due to the rear exhaust pipe 63 or the occurrence of the situation in which the bank angle of the vehicle is limited by the rear exhaust pipe 63.
[0032]
The muffler 90, as shown in Fig. 1 and Fig. 2, includes a cylindrical body 100, and the cylindrical body 100 is constituted of a first muffler portion 91 which is positioned between the crankcase 41 and the rear wheel 8, a second muffler portion 92 which extends in a projecting manner toward a side (right side) of the rear wheel 8 and is positioned at such a portion, and a connection portion 93 which integrally connects these muffler portions 91, 92 with smooth curves.
[0033]
Fig. 6 (A) is a plan view of the muffler 90, and Fig. 6 (B) is a side view of the muffler 90. The cylindrical body 100 is, as shown in Fig. 6(A) and Fig. 6(B), formed by vertically

joining cases lOOA, lOOB which are split in two vertically by welding.
Stays 101, 102 are respectively mounted on front and rear portions of the upper case lOOA of the cylindrical body 100, and the cylindrical body 100 is supported on the vehicle body frame 2 by way of these stays 101, 102. Further, to the lower case lOOB, a stopper 103 is joined by welding at a position corresponding to a lower surface of the connection portion 93. The stopper 103 is brought into contact with a stopper portion 30C of the main stand 30 when the main stand 30 is rotated to the storing position thus functioning as a stopper of the main stand 30.
[0034]
In the above-mentioned constitution, the muffler 90 includes the first muffler portion 91 which is positioned between the crankcase 41 and the rear wheel 8, the second muffler portion 92 which is positioned in a projecting manner toward the side (right side) of the rear wheel 8, and a connection portion 93 which integrally connects these muffler portions 91, 92. Accordingly, a space capacity necessary for the muffler 90 can be distributed at a front side and a lateral side of the rear wheel 8, Accordingly, compared to the constitution which arranges the muffler having the same space capacitance between the crankcase 41 and the rear wheel 8, it is unnecessary to increase a wheel base thus realizing the

miniaturization of the vehicle. [0035]
Fig. 7(A) is a plan view showing the lower case lOOB of the muffler 90 together with the peripheral constitution thereof, and Fig. 7 (B) is a side view of the muffler 90 together with the peripheral constitution. In the lower case lOOB, as shown in Fig. 7(A) and Fig. 7(B), an opening portion 110 is formed in a front end wall lOOBl obliquely in the frontward and downward direction, as shown in Fig. 8, a cylindrical exhaust pipe connection pipe 120 is obliquely mounted on the opening portion 110, and the rear exhaust pipe 63 is connected to the exhaust pipe connection pipe 120. Due to such a constitution, the rear exhaust pipe 63 and the exhaust pipe connection pipe 120 communicate with each other.
As shown in Fig, 8, a plurality of open holes 120A is formed on a peripheral surface of the exhaust pipe connection pipe 120 and, at the same time, an opening formed in a rear end of the exhaust pipe connection pipe 120 is closed by a plate 120B (see Fig, 7 (A) ) . Due to such a constitution, the exhaust gas discharged from the rear exhaust pipe 63 is discharged from the above-mentioned plurality of open holes 120A and is expanded in the inside of a chamber (an expansion chamber) Rl of the first muffler portion 91, and the exhaust gas in the inside of the chamber flows into the second muffler portion
ao

The second muffler portion 92 is partitioned into three expansion chambers (a first expansion chamber RIA communicated with the expansion chamber Rl, a second expansion chamber R2, a third expansion chamber R3) by way of a first partition wall 130 and the second partition wall 131, As shown in Fig. 7(A), a first communication pipe 132 which communicates with the first expansion chamber RIA is fixed to the first partition wall 130 in a penetrating manner, and the first communication pipe 131 communicates with the second expansion chamber R2 by traversing the third expansion chamber R3 and the second partition wall 131.
A second communication pipe 133 is fixed to the second partition wall 131 at a position where the second communication pipe 133 does not interfere with the first communication pipe 132, to be more specific, at a position displaced to the outside of the vehicle from the first communication pipe 132 in a penetrating manner, and the second expansion chamber R2 and the third expansion chamber R3 communicate with each other due to this second communication pipe 133.
[0037]
Further, to the second partition wall 131, a third communication pipe 134 which communicates with the third expansion chamber R3 is fixed in a penetrating manner at a position where the third communication pipe 134 does not

interfere with the above-mentioned first and second communication pipes 132, 133, that is, at a position where the third communication pipe 134 is displaced to the vehicle body side from the first communication pipe 132. The third communication pipe 134 traverses the second expansion chamber R2 and penetrates the rear end wall 100B2 of the lower case lOOB. Due to such a constitution, the third communication pipe 134 functions as a tail pipe which discharges the exhaust gas in the inside of the muffler 90 to the outside of the muffler 90.
The third communication pipe 134, as shown in Fig. 7 (B) , is inclined obliquely in the downward direction toward a rear side of the vehicle body and, at the same time, as shown in Fig. 7(A), penetrates the second partition wall 131 with the inclination which is inclined obliquely in the downward direction toward the side of the vehicle body, and as shown in Fig. 9, penetrates a rear end wall 100B2 of the lower case lOOB, and is fixed to the second partition wall 131 and the rear end wall 100B2 by welding. Due to such a constitution, the tail pipe is arranged obliquely as well as in the oblique outside direction with respect to the vehicle body and hence, the entanglement of the exhaust gas can be reduced whereby the smear on the rear portion of the vehicle body attributed to the exhaust gas can be reduced.

Due to the above-mentioned muffler structure, the exhaust gas which is discharged from the engine 6 is purified by the catalyst chamber 80 which is positioned in the middle portion of the exhaust pipe 61 and, thereafter, enters the inside of the muffler 90. As indicated by an arrow in Fig. 7 (A) , the exhaust gas enters the inside of the expansion chamber Rl of the first muffler portion 91 and, thereafter, enters the first expansion chamber RIA in the inside of the second muffler portion 92, and enters the second expansion chamber R2 after passing through the first communication pipe 132. Then, the exhaust gas reverses the flow direction thereof and enters the third expansion chamber R3 after passing through the second communication pipe 133. Thereafter, the exhaust gas reverses the flow direction thereof and is discharged to the outside of the muffler 90 after passing through the third communication pipe 134.
In this manner, the exhaust gas is expanded in the expansion chamber Rl of the first muffler portion 91 and, thereafter, the flow of the exhaust gas is reversed in the inside of the second muffler portion 92 and, thereafter, the exhaust gas is expanded in the plurality of expansion chambers R2, R3. Accordingly, it is possible to ensure the large muffler capacities of the first muffler portion 91 and the second muffler portion 92 thus sufficiently reducing an exhaust sound.

Further, a bottom shape of the second muffler portion 92 which is arranged on a side of the rear wheel 8 is, as shown in Fig, 10 to Fig. 13, formed in an inclined shape which is inclined in the substantially oblique upward direction toward a right side of the vehicle body from the vehicle body side (rear wheel 8 side) substantially along a right inclined surface LO of the vehicle body which connects ground contact points of the front and rear wheels and the outer-end lower portion of the main step 36. Due to such a constitution, the capacity of the second muffler portion 92 can be sufficiently ensured while avoiding the occurrence of the situation in which the bank angle of the vehicle is limited by the second muffler portion 92 or the occurrence of the situation in which the lowermost ground height of the vehicle is lowered.
[0040]
In this embodiment, the side-surface opening portion 82 which constitutes one of the exhaust passages corresponding to the inlet and the outlet of the catalyst chamber 80 is formed in the side wall of the catalyst chamber 80. Accordingly, the front exhaust pipe 62 constituting the bent pipe which extends from the exhaust port 43B and is bent can be connected to the above-mentioned side-surface opening portion 82 and hence, compared to the catalyst arrangement structure which arranges the catalyst chamber in the straight line portion of the exhaust

pipe, the catalyst chamber 80 can be arranged in a compact manner. Further, the degree of freedom in the arrangement of the catalyst chamber 80 and the degree of freedom in designing the exhaust pipe can be enhanced. In this manner, according to the constitution of this embodiment, the catalyst chamber 8 0 can be arranged in a compact manner in the space below the cylinder 42A, that is, in the space below the cylinder block 42 and the cylinder head 43 as well as in the space in front of the crankcase 41.
[0041]
Further, the above-mentioned side-surface opening portion 82 is made to face the side surface of the catalyst 85 and hence, the catalyst chamber 80 can be arranged close to the cylinder head 43 (close to the front side of the engine) whereby it is possible to easily layout the catalyst chamber 8 0 in the space below the cylinder 42A. Further, the exhaust gas from the engine 6 passes through the catalyst 85 after turning around the periphery of the catalyst 85 and hence, a flow speed of the exhaust gas which passes through the catalyst 85 can be suppressed. Still further, the catalyst 85 is arranged along the axis of the exhaust passage of the rear exhaust pipe 63 and hence, the catalyst chamber 80 can be miniaturized.
[0042]
Further, the side-surface opening portion 82 of the

catalyst chamber 80 is opened toward the exhaust port 43B and hence, the temperature of the catalyst 85 easily arrives at the activation temperature due to heat of the high-temperature exhaust gas from the exhaust port 43B whereby at the time of performing a cold engine, the catalyst 85 can be activated within a relatively short time immediately after starting the engine 6 and, at the same time, water from the outside hardly intrudes into the side-surface opening portion 82 thus preventing the catalyst 85 from being splashed with water.
Further, according to the constitution of this embodiment, the recessed portions 81C, 81D are formed by depressing the upper portion and the lower portion of the cylindrical case 81 of the catalyst chamber 80 and the catalyst 85 is held by these recessed portions 81C, 81D and hence, an additional fixing member for fixing the catalyst 85 is not necessary whereby the production cost can be reduced. Further, the catalyst chamber 80 is formed by vertically joining two cases 81A, 81B and hence, the catalyst 85 can be held by joining the cases 81 A, 8IB thus facilitating the assembly of the catalyst 85.
[0043]
Further, in this embodiment, the muffler 90 includes the first muffler portion 91 which is positioned between the engine 6 and the rear wheel 8, the second muffler portion 92 which is positioned in a projecting manner toward the side (right

side) of the rear wheel 8, and the connection portion 93 which integrally connects these muffler portions 91, 92 and hence, the capacity necessary for the muffler 90 can be dispersed to the front side and the lateral side of the rear wheel 8 whereby it is unnecessary to elongate the wheel base thus realizing the miniaturization of the vehicle.
Further, the rear exhaust pipe 63 passes below the center of vehicle body, is bent obliquely in the upward direction with respect to the vehicle body at a rear portion of the engine 6, and is connected to the first muffler portion 91. Accordingly, the bending of the exhaust pipe is not increased and hence, the exhaust pipe can be easily formed, the high accuracy can be easily ensured, and the exhaust resistance can be reduced.
[0044]
Further, the above-mentioned muffler 90 is formed by vertically joining the upper case lOOA and the lower case lOOB and hence, the manufacture and the assembly of the muffler 90 are facilitated thus enhancing the productivity. Further, the rear exhaust pipe 63 is inserted into the connection portion of the first muffler portion 91 in the oblique upward direction from the front lower side and hence, the bending of the rear exhaust pipe 63 is not large whereby the exhaust resistance can be reduced and, at the same time, the rear exhaust pipe 63 can be connected to the first muffler portion 91 at a position

where the rear exhaust pipe 63 does not interfere with welding beads (seam) of the upper and lower cases lOOA, lOOB.
Further, the stopper 103 of the main stand 30 is arranged at the connection portion 93 which connects the first muffler portion 91 and the second muffler portion 92 and hence, the stopper 103 can also function as a reinforcing member which reinforces the connection between the above-mentioned muffler portions 91, 92.
Still further, the tail pipe is arranged at the second muffler portion 92 in a state that the tail pipe is directed in the oblique downward direction as well as in the oblique outward direction and hence, the entanglement of the exhaust gas can be reduced thus decreasing smears on the rear portion of the vehicle body attributed to the exhaust gas.
[0045] (Second embodiment)
it pipe 161 and the catalyst chamber 180, Fig. 16 is a f the exhaust pipe 161 and the catalyst chamber 180 as
Fig. 14 is a side view showing a catalyst chamber 180 according to a second embodiment together with an engine 6. Further, Fig. 15(A) is a plan view of an exhaust pipe 161 and the catalyst chamber 180, Fig. 15(B) is a side view of the exhaust pipe 161 and the catalyst chamber 180, Fig. 16 is a view o
viewed from a front side, and Fig. 17 is a longitudinal cross-sectional view of the exhaust pipe 161 and the catalyst chamber 180. Here, in the second embodiment, parts identical

with the parts of the first embodiment are given same numerals and their repeated explanation is omitted.
As shown in Fig. 14, the engine 6 is a horizontal single cylinder engine (horizontal engine) which includes a crankcase 41, a cylinder block 42 which is connected to a front portion of the crankcase 41, a cylinder head 43 which is connected to a front portion of the cylinder block 42, and a head cover 44 which is connected to a front portion of the cylinder head 43, wherein a cylinder in the inside of the cylinder block 42 is horizontally arranged.
[0046]
An exhaust unit 60 which constitutes an exhaust system of the engine 6 includes an exhaust pipe 161, a catalyst chamber 180 and a muffler 190 described later. The exhaust pipe 161 includes a front exhaust pipe 162 which connects the engine 6 and the catalyst chamber 180 and a rear exhaust pipe 163 which connects the catalyst chamber 180 and the muffler 90.
The front exhaust pipe 162 is a bent pipe which is bent so as to be accommodated within a width of the engine 6. To be more specific, as shown in Fig. 14 and Fig. 16, the front exhaust pipe 162 extends downwardly from an exhaust opening of the cylinder head 43 at a front right side of the catalyst chamber 180, extends rearwardly while being bent and wound around the catalyst chamber 180 toward a left side of the catalyst chamber 180, and opens toward a vehicle body side

(right side) below the cylinder block 42 . The catalyst chamber 80 is connected to an open end of the exhaust pipe 162.
[0047]
The rear exhaust pipe 163 extends, as shown in Fig. 14, rearwardly below the crankcase 41 from a rear end of the catalyst chamber 80. The rear exhaust pipe 163 changes, as shown in Fig. 15(B), a cross-sectional shape thereof from a perfect circular shape into a laterally-elongated elliptical shape and, thereafter, returns the cross-sectional shape from the laterally-elongated elliptical shape into the perfect circular shape again. Further, these cross-sectional shapes have the substantially same cross-sectional area.
The reason that the cross-sectional shape of the rear exhaust pipe 163 is changed in this manner is as follows.
As shown in Fig. 14, a lower surface of the crankcase 41 includes a front inclined surface 41A which is inclined rearwardly and downwardly from a connection portion between the crankcase 41 and the cylinder block 42, a horizontal surface 41B which extends rearwardly from a lower end of the front inclined surface 41C in a substantially horizontal manner, and a rear inclined surface 41C which is inclined rearwardly and upwardly from a rear end of the horizontal surface 41B, Under such a constitution, when the rear exhaust pipe 163 is formed to have a perfect circular cross-sectional shape along the whole length, to ensure a sufficient cross-sectional area of

the rear exhaust pipe 163^ there may be a case that the rear exhaust pipe 163 is arranged at a position below a horizontal surface 4IB which constitutes a lowermost surface of the crankcase 41 and lower than a minimum grand height which the rear exhaust pipe 163 aims at.
[0048]
In view of the above, in the rear exhaust pipe 163 of this embodiment, to change the height of the rear exhaust pipe 163 (a diameter of the rear exhaust pipe 163 in the vertical direction of the vehicle body) along the front inclined surface 41A, the horizontal surface 41B and the rear inclined surface 41C, that is, along the inclination of a lower surface of the crankcase 41, the cross-sectional shape of the rear exhaust pipe 163 is changed from the perfect circular shape to the laterally-elongated elliptical shape and, thereafter, from the laterally-elongated elliptical shape to the perfect circular shape again thus ensuring the sufficient minimum ground height while maintaining the substantially uniform exhaust resistance of the rear exhaust pipe 163.
[0049]
Next, the catalyst chamber 180 is explained in detail. The catalyst chamber 180 is, as shown in Fig. 14, arranged below the cylinder block 42 of the engine 6 and the crankcase 41. The catalyst chamber 180 includes a catalyst housing portion 180A which houses a catalyst 85 therein and a bulging portion

180B which projects toward the engine 6 side (vehicle-body upper side) from the catalyst housing portion 180A along the cylinder block 42 and the crankcase 41*
As shown in Fig. 15(A) and Fig. 15 (B), the catalyst chamber 180 includes a cylindrical case 181 which is integrally formed of the catalyst accommodating portion 180A and the bulging portion 180B, and the cylindrical case 181 is formed by joining a left case 181A and a right case 181B which are respectively formed in a substantially bowl shape to each other.
[0050]
In a side surface of the bulging portion 180B of the cylindrical case 181, that is, in an upper portion of a side surface of the left case 181A, as shown in Fig. 16, a side-surface opening portion 182 which opens in the vehicle-body width direction (vehicle-body leftward direction) is formed. The side-surface opening portion 182 corresponds to an exhaust passage which constitutes either one of an inlet and outlet of the catalyst chamber 80, and a rear end of the front exhaust pipe 162 is inserted and joined to the side-surface opening portion 182 by welding.
[0051]
On a rear end portion of the catalyst accommodating portion 180A of the cylindrical case 181, as shown in Fig. 17, an opening portion 183 which opens in the rearward direction

is formed. The opening portion 183 corresponds to an exhaust passage which constitutes another of the inlet and outlet of the catalyst chainber 80, The rear exhaust pipe 63 is joined to the opening portion 183 by welding in a state that a front end of the rear exhaust pipe 63 is inserted into the inside of the case 181, and the catalyst 85 is fixed to the front end portion from the inside of the case 181, Due to such a constitution, an axis of the catalyst 85 is aligned with the passage direction of the rear exhaust pipe 163 and hence, the catalyst 85 and the rear exhaust pipe 63 are coaxially arranged whereby the catalyst 85 is arranged along an axis of the exhaust passage of the rear exhaust pipe 163 and, at the same time, the front exhaust pipe 162 can be opened within a width of the catalyst 85 in the length direction.
[0052]
Here, the constitution which discharges an exhaust gas form an engine toward a catalyst in the inside of a catalyst chamber has a possibility of generating vibrations of the catalyst or the like.
To the contrary, this embodiment, as described above, forms the bulging portion 180B which bulges from the catalyst accommodating portion 180A of the catalyst chamber 180, and connects the front exhaust pipe 162 to the side-surface opening portion 182 of the bulging portion 180B and hence, the exhaust passage from the engine 6 communicates with the catalyst

chamber at a position which is offset from the catalyst 85.
[0053]
Accordingly, the exhaust gas from the engine 6 is, as indicated by a wave arrow G in Fig. 16, not discharged toward the catalyst 85 but is discharged toward an inner wall 180B1 of the bulging portion 18OB of the catalyst chamber 180, impinges on the inner wall 180B1 and, thereafter, flows toward the catalyst 85 and passes through the catalyst 85. Accordingly, a flow speed of the exhaust gas is lowered due to the impingement of the exhaust gas on the inner wall 180B1 and, at the same time, due to the expansion of the exhaust gas in the inside of the bulging portion 180B and, thereafter, the exhaust gas passes through the catalyst 85. Accordingly, it is possible to surely suppress the flow speed of the exhaust gas which passes through the catalyst 85 thus avoiding the above-mentioned generation of vibrations.
[0054]
Fig. 18(A) is a plan view of a muffler 190 and Fig. 18B is a side view of the muffler 190. The muffler 190 includes a cylindrical body 200 which is formed by vertically joining cases 200A, 2GOB which are split in two vertically. The cylindrical body 200 is constituted of a first muffler portion 191 which is positioned between the crankcase 41 and the rear wheel 8, a second muffler portion 192 which extends toward a side (right side) of the rear wheel 8 in a projecting manner

and is positioned at the side of the rear wheel 8, and a connecting portion 193 which connects these muffler portions 191, 192 along a smooth curved line.
The muffler 190 is, in the same manner as the first embodiment, configured such that a capacity required by the muffler 190 is dispersed to a front and the side of the rear wheel 8. Accordingly, compared to the constitution which arranges a muffler having the same capacity between the crankcase 41 and the rear wheel 8, it is unnecessary to elongate a wheel base and hence, a vehicle can be miniaturized.
[0055]
Fig. 19(A) is a plan view of a lower case 200B of the muffler 190 in which the peripheral constitution of the lower case 200B is also shown, and Fig. 19(B) is a side view of the lower case 20OB and the peripheral constitution. A cylindrical exhaust-pipe connecting pipe 120 is mounted on a front portion of the lower case 200B in a state that the connecting pipe 12 0 opens obliquely in the frontward and downward direction. A rear exhaust pipe 163 is connected to the exhaust-pipe connecting tube 120. An exhaust gas which is discharged from the rear exhaust pipe 163 is discharged from a plurality of opening holes 120A and is expanded in the inside of a first expansion chamber (chamber) Rl of the of the first muffler portion 191 and the exhaust gas in the inside of the expansion chamber Rl is made to flow into the second muffler

portion 192.
The second muffler portion 192 is partitioned into three expansion chambers (a first expansion chamber RIA which communicates with the expansion chamber Rl, a second expansion chamber R2, a third expansion chamber R3) via a first partition wall 130 and a second partition wall 131. A first communication pipe 132, a second communication pipe 133 and a third communication pipe 134 which also functions as a tail pipe are fixed to the respective expansion chambers RIA, R2 and R3.
[0056]
Due to the above-mentioned structure, the exhaust gas discharged from the engine 6 is purified by the catalyst chamber 180 and, thereafter, enters the inside of the muffler 190. Then, as indicated in Fig. 19 (A) and (B) , the exhaust gas enters the expansion chamber Rl of the first muffler portion 191 and, thereafter, enters the first expansion chamber RIA in the inside of the second muffler portion 192 and, thereafter, enters the second expansion chamber R2 through the first communication pipe 132. Then, the exhaust gas reverses a flow thereof and enters the third expansion chamber R3 through the second communication pipe 133 and, thereafter, changes the flow direction thereof and is discharged to the outside of the muffler 190 through the third communication pipe 134.
In this embodiment, as shown in Fig. 19(A) and Fig. 19(B),

since a plurality (three in this embodiment) of communication pipes 132, 133, 134 fixed to the second partition wall 131 are longitudinally arranged arrangement space for these communication pipes 132, 133, 134 can be made narrow in width and the degree of freedom can be enhanced with respect to the shape of the muffler 190. [0057]
In this embodiment, to the side surface of the bulging portion 180B of the catalyst chamber 180, the front exhaust pipe 162 which corresponds to one exhaust passage is connected. Accordingly, in addition to the advantageous effects acquired by the first embodiment, the exhaust passage from the engine 6 communicates with the catalyst chamber 180 at the position offset from the catalyst 85 in the catalyst chamber 180 and hence, it is possible to allow the exhaust gas to flow the catalyst 85 after lowering the flow speed of the exhaust gas in the inside of the catalyst chamber 180. Accordingly, the generation of vibrations of the catalyst 85 or the like can be prevented.
[0058]
Further, the above-mentioned bulging portion 180B bulges toward the engine 6 side along the cylinder block 42 and the crankcase 41 and hence, the bulging portion 180B can be arranged in a dead space defined between the cylinder block 42 and the crankcase 41 thus enhancing a layout efficiency of

the bulging portion 180B. Further, the exhaust pipe 162 is connected with the catalyst chamber 180 after wrapping around a periphery of the catalyst chamber 180 thus making the flow of the exhaust gas smooth.
[0059]
Although the invention has been explained in conjunction with one embodiment heretofore, it is apparent that the invention is not limited to such an embodiment. For example, the catalyst chambers 80, 180 may be formed of a pipe forming product, Further, in the respective above-mentioned embodiments, the explanation has been made with respect to a case in which the exhaust gas from the engine 6 is introduced from the side-surface opening portions 82, 182 of the catalyst chamber 80, is made to pass the catalyst 85 in the inside of the catalyst chamber 80 and is discharged from the opening portions 83, 183 in the rear end of the catalyst chambers 80, 180. However, the exhaust gas may be made to flow in the opposite direction. That is, the exhaust gas of the engine 6 may be introduced into the catalyst chamber 80, 180 from the opening portions 83, 183 of the catalyst chambers 80, 180, is made to pass through the catalyst 85, and is discharged from the side-surface opening portion 82-
Further, in the above-mentioned embodiment, the explanation has been made with respect to a case in which the invention is applied to the motorcycle which mounts the

horizontal single cylinder engine in which the cylinder is arranged horizontally. However, the invention is not limited to such an embodiment and is broadly applicable to the motorcycle which mounts an upright engine in which a cylinder is erected vertically or a multi-cylinder engine thereon. [Brief Description of the Drawings]
[0060]
[Fig. 1] A side view of a motorcycle according to a first embodiment.
[Fig. 2] A top plan view showing a vehicle body frame of the motorcycle together with the peripheral constitution.
[Fig. 3] (A) being a plan view of an exhaust pipe and a catalyst chamber, and (B) being a side view of the exhaust pipe and the catalyst chamber.
[Fig. 4] A view showing a front exhaust pipe together with the catalyst chainber.
[Fig. 5] A cross-sectional view taken along a line V-V in Fig. 4.
[Fig. 6] (A) being a plan view of a muffler, and (B) being a side view of the muffler.
[Fig. 7] (A) being a plan view showing a lower case of the muffler together with the peripheral constitution, and (B) being a side view of the lower case of the muffler together the peripheral constitution.
[Fig. 8] A view showing an exhaust pipe connection pipe

together with the peripheral constitution.
[Fig. 9] A view showing a third communication pipe together with the peripheral constitution.
[Fig. 10] A cross-sectional view taken along a line X-X in Fig. 7 (B) .
[Fig. 11] A cross-sectional view taken along a line XI-XI in Fig. 7 (B) .
[Fig. 12] A cross-sectional view taken along a line XII-XII in Fig. 7(B).
[Fig. 13] A cross-sectional view taken along a line XIII-XIII in Fig. 7(B).
[Fig. 14] A side view showing a catalyst chamber according to a second embodiment together with an engine.
[Fig. 15] (A) being a plan view of an exhaust pipe and a catalyst chamber, and (B) being a side view of the exhaust pipe and the catalyst chamber.
[Fig. 16] A view of the exhaust pipe and the catalyst chamber as viewed from a front side.
[Fig, 17] A cross-sectional view taken along a line XVII-XVII in Fig. 15(A).
[Fig. 18] (A) being a plan view of a muffler, and (B) being a side view of the muffler.
[Fig. 19] (A) being a plan view showing a lower case of the muffler together with the peripheral constitution, and (B) being a side view of the lower case of the muffler together

the peripheral constitution.
[Description of Reference Numerals and Signs]
[0061] 1: motorcycle 2: vehicle body 6: engine (horizontal engine) 30: main stand 31: side stand 42A: cylinder 43A: intake port 43B: exhaust port 60: exhaust unit
61, 161: exhaust pipe
62, 162: front exhaust pipe
63, 163: rear exhaust pipe 80, 180: catalyst chamber

82, 182: side-surface opening portion
83, 183: opening portion 85: catalyst

91, 191
92, 192
93, 193
90, 190: muffler
first muffler portion
second muffler portion
connection portion 103: stopper 180A: catalyst accommodating portion

180B: bulging portion
LO: vehicle-body right inclined surface
Rl, R1A, R2, R3: expansion chamber










[Designation of Document] Claims [Claim 1]
A catalyst arrangement structure of a motorcycle which arranges a catalyst chamber on a middle portion of an exhaust pipe which connects an exhaust port of a cylinder head and a muffler, wherein out of exhaust passages corresponding to an inlet and an outlet of the catalyst chamber, an axis of a catalyst is aligned with the passage direction of one exhaust passage, and another exhaust passage is opened within a width in the length direction of the catalyst. [Claim 2]
A catalyst arrangement structure of a motorcycle according to claim 1, wherein a catalyst is arranged along an axis of one exhaust passage, and an opening formed in a side surface of the catalyst chamber which constitutes an opening of another exhaust passage faces a side surface of the catalyst. [Claim 3]
A catalyst arrangement structure of a motorcycle according to claim 2, wherein the opening formed in the side surface of the catalyst chamber is an opening which is directed to the exhaust port. [Claim 4]
A catalyst arrangement structure of a motorcycle according to any one of claims 1 to 3, wherein the catalyst is held in a recessed portion of the catalyst chamber.

A catalyst arrangement structure of a motorcycle according to claim 1, wherein another exhaust passage communicates with the catalyst chamber at a position offset from a catalyst in the catalyst chamber* [Claim 6]
A catalyst arrangement structure of a motorcycle according to claim 5, wherein a bulging portion which bulges toward an engine along a cylinder block of the engine and a crankcase is formed on the catalyst chamber, and another exhaust passage communicates with the bulging portion. [Claim 7]
A catalyst arrangement structure of a motorcycle . according to claim 5 or claim 6, wherein another exhaust passage is formed into a shape which wraps around a periphery of the catalyst chamber and communicates with a side surface of the catalyst chamber. [Claim 8]
A catalyst arrangement structure of a motorcycle according to any one of claims 1 to 1, wherein the catalyst chamber is arranged below a cylinder of a horizontal engine.


Documents:

1108-CHE-2007 EXAMINATION REPORT REPLY RECEIVED 04-10-2010.pdf

1108-CHE-2007 POWER OF ATTORNEY 04-10-2010.pdf

1108-CHE-2007 AMENDED PAGES OF SPECIFICATION 04-10-2010.pdf

1108-CHE-2007 AMENDED CLAIMS 04-10-2010.pdf

1108-che-2007 form-3 04-10-2010.pdf

1108-che-2007 form-5 04-10-2010.pdf

1108-CHE-2007 OTHER PATENT DOCUMENT 04-10-2010.pdf

1108-che-2007-abstract.pdf

1108-che-2007-claims.pdf

1108-che-2007-correspondnece-others.pdf

1108-che-2007-description(complete).pdf

1108-che-2007-drawings.pdf

1108-che-2007-form 1.pdf

1108-che-2007-form 18.pdf

1108-che-2007-form 26.pdf

1108-che-2007-form 3.pdf

1108-che-2007-form 5.pdf

abs-1108-che-2007.jpg


Patent Number 243542
Indian Patent Application Number 1108/CHE/2007
PG Journal Number 44/2010
Publication Date 29-Oct-2010
Grant Date 22-Oct-2010
Date of Filing 28-May-2007
Name of Patentee HONDA MOTOR CO., LTD.
Applicant Address 1-1, MINAMI-AOYAMA 2-CHOME, MINATO-KU, TOKYO 107-8556, JAPAN.
Inventors:
# Inventor's Name Inventor's Address
1 IKEDA, HIDEKI C/O HONDA R&D CO LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193, JAPAN.
2 YAMAGUCHI, MASAAKI C/O HONDA R&D CO., LTD, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193, JAPAN.
3 NARAZAKI, YASUO C/O HONDA R&D CO., LTD, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193, JAPAN.
4 KUSANO, TAKUHEI C/O HONDA R&D CO., LTD, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193, JAPAN.
5 INOKAWA, HIROSHI C/O HONDA R&D CO., LTD, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193, JAPAN.
PCT International Classification Number B62J23/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2006-259959 2006-09-26 Japan
2 2006-152619 2006-05-31 Japan