JP4693733B2 - Catalyst arrangement structure for motorcycles - Google Patents

Description

  The present invention relates to a catalyst arrangement structure for a motorcycle in which a catalyst chamber is arranged in the middle of an exhaust pipe connecting an exhaust port and a muffler.

  In general, a motorcycle having a catalyst chamber in the middle of an exhaust pipe connecting an exhaust port and a muffler is known. In this type, in order to give the catalyst in the catalyst chamber sufficient purification performance, it is necessary to place the catalyst at the center position where the exhaust gas flows and to contact the exhaust gas and the catalyst for a long time. desirable. However, when the catalyst is arranged at the center position where the exhaust gas flows, the flow rate of the exhaust gas is higher at the center position. Therefore, the flow rate of the exhaust gas flowing into the catalyst becomes too fast and the purification time is shortened.

In order to solve this problem, conventionally, a large-capacity catalyst chamber is connected in the middle of a linearly extending exhaust pipe having an inlet / outlet, and the catalyst is arranged in the catalyst chamber with the axis shifted, and the exhaust gas flowing in from the inlet There has been proposed a catalyst arrangement structure in which the gas flow velocity is once reduced in the chamber, and then guided to the catalyst to perform sufficient purification and then discharged from the chamber outlet (see, for example, Patent Document 1).
JP 2002-317627 A

  However, in the above conventional structure, the exhaust pipe and the axis of the catalyst are shifted, so the catalyst chamber becomes large. Further, since the catalyst chamber is arranged in the straight portion of the exhaust pipe, the exhaust pipe becomes long and a compact arrangement cannot be made.

  Accordingly, an object of the present invention is to provide a catalyst arrangement structure for a motorcycle in which catalyst chambers are arranged in a compact manner.

In order to solve the above-mentioned problem, the present invention provides an exhaust pipe ( 43,) of a cylinder head (43 ) and a muffler (90, 190) in a horizontal engine (6) in which a cylinder (42A) is disposed horizontally. 61, 161) , in the catalyst arrangement structure of the motorcycle in which the catalyst chamber (80, 180) is arranged, the crankcase (41) of the horizontal engine (6) is arranged behind the cylinder (42A). together, are formed so as to bulge downward from the cylinder bottom, the front of the catalyst chamber (80, 180) is the crankcase (41) and, disposed in the cylinder below, the catalyst chamber (80, 180) the exhaust channel corresponding to doorways, catalyst passages direction of the muffler one exhaust passage towards (90,190) (83,183) ( Align the axial center of the 5), the exhaust port (the other exhaust passage towards 43B) (82 and 182) is opened within the width in the longitudinal direction of the catalyst (85), the catalyst chamber (80, 180) The front end position is formed in front of the position where the other exhaust passage (82, 182) opens in the side surface of the catalyst chamber (80, 180) .
According to this invention, among the exhaust passages corresponding to the entrance and exit of the catalyst chamber, the axis of the catalyst is aligned with the passage direction of one exhaust passage, and the other exhaust passage is opened within the width in the length direction of the catalyst. Therefore, the catalyst chamber can be connected to the bent pipe constituting the exhaust pipe, and the catalyst chamber can be arranged compactly. Further, the catalyst chamber can be reduced in size. Further, since the opening on the side surface of the catalyst chamber faces, the exhaust gas enters the catalyst from the periphery of the catalyst, and the flow rate of the exhaust gas passing through the catalyst can be suppressed. In addition, the temperature of the catalyst can easily reach the activation temperature due to the heat of the hot exhaust gas from the exhaust port, and it is difficult for water from the outside to enter the side opening, preventing the catalyst from getting wet. Can do. Further, if the catalyst chamber is arranged below the cylinder of the horizontal engine, it is possible to avoid a situation where the minimum ground clearance of the vehicle or a bank angle of the vehicle is limited by the catalyst chamber.

In the above configuration, the catalyst (85) is disposed in the catalyst chamber (80, 180) with a clearance in the circumferential direction, and the catalyst (85) is disposed along the axis of the one exhaust passage (83, 183). 85) and a rear exhaust pipe (63, 163) extending along the axial direction of the catalyst (85) and connected to the muffler (90, 190) is connected to the other exhaust passage (82, 182). It is preferable that a front exhaust pipe (62, 162) connected to the exhaust port (43B) is connected to the opening .

Further, in the above configuration, the catalyst (85) is disposed in the catalyst chamber (80, 180) with a gap in the circumferential direction, and is disposed along the axis of the one exhaust passage (83, 183). A catalyst (85) is disposed, a rear exhaust pipe (63, 163) extending along the axial direction of the catalyst (85) and connected to the muffler (90, 190) is connected, and the other exhaust passage (82, 182) is opened to the gaps, it is not preferable to connect the front exhaust pipe (62, 162) communicating with the exhaust port to the opening (43B).

In the above configuration, the catalyst (85) is preferably held by the recesses (81C, 81D) of the catalyst chamber (80) . According to this configuration, a separate fixing member for fixing the catalyst is not required, and the manufacturing cost can be reduced.

In the above configuration, it is preferable that the other exhaust passage (82, 182) communicates with a position offset from the catalyst (85) in the catalyst chamber (80, 180) . According to this configuration, the exhaust gas can be passed through the catalyst chamber after its flow rate is lowered, and vibration of the catalyst or the like can be avoided.

In the above configuration, the catalyst chamber (180 ) is provided with a bulging portion (180B) that bulges toward the engine along the cylinder block (42) and the crankcase (41) of the engine (6). The other exhaust passage (182) is preferably passed through the bulging portion (180B) . According to this configuration, the bulging portion can be laid out at a dead pace between the cylinder block and the crankcase, and the layout efficiency can be increased.

In the above structure, the other exhaust passage (182), it is preferable that a shape leading to the side surface of the catalyst chamber (180) flows around the periphery of said catalyst chamber (180). According to this configuration, the flow of exhaust gas can be made smooth.

In the present invention, among the exhaust passages corresponding to the entrance and exit of the catalyst chamber, the axis of the catalyst is aligned with the passage direction of one exhaust passage, and the other exhaust passage is opened within the width in the length direction of the catalyst. The catalyst chamber can be connected to the bent pipe constituting the exhaust pipe, and the catalyst chamber can be arranged in a compact manner.
In addition, the catalyst is arranged along the axis of one exhaust passage, and the opening on the side of the catalyst chamber, which is the opening of the other exhaust passage, faces the side of the catalyst, so that the catalyst chamber can be reduced in size. In addition, the flow rate of the exhaust gas that enters the catalyst from the periphery of the catalyst and passes through the catalyst can be suppressed.
In addition, since the opening on the side surface of the catalyst chamber is an opening toward the exhaust port, the temperature of the catalyst can be easily reached by the heat of the high-temperature exhaust gas, and water from the outside is supplied to the side surface opening. It is difficult to enter and the catalyst can be prevented from getting wet.
In addition, since the catalyst is held in the concave portion of the catalyst chamber, a separate fixing member for fixing the catalyst is not required, and the manufacturing cost can be reduced.

Further, since the other exhaust passage is led to a position offset from the catalyst in the catalyst chamber, the exhaust gas can be passed through the catalyst chamber after the flow rate is lowered, and vibration of the catalyst or the like is avoided. be able to.
In addition, the catalyst chamber is provided with a bulging portion that bulges to the engine side along the engine cylinder block and the crankcase, and the other exhaust passage is passed through the bulging portion. The bulge can be laid out at a dead pace.
In addition, since the other exhaust passage has a shape that goes around the catalyst chamber and is connected to the side surface of the catalyst chamber, the flow of the exhaust gas can be made smooth.
Further, since the catalyst chamber is disposed below the cylinder of the horizontal engine, it is possible to avoid a situation where the minimum ground clearance of the vehicle and a bank angle of the vehicle are limited by the catalyst chamber.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the description, descriptions of directions such as front and rear, left and right, and top and bottom are for the vehicle body.
<First Embodiment>
FIG. 1 is a side view of the motorcycle according to the first embodiment.
The motorcycle 1 includes a body frame 2, a pair of left and right front forks 3 rotatably supported by a head pipe 20 attached to a front end of the body frame 2, and steering attached to an upper end portion of the front fork 3. Handle 4, a front wheel 5 rotatably supported at the lower end of the front fork 3, an engine 6 supported by the vehicle body frame 2 at the approximate center of the vehicle body, and supported by the vehicle body frame 2 so as to be swingable up and down. A rear fork 7, a rear wheel 8 rotatably supported at the rear end of the rear fork 7, and left and right rear cushions 9 disposed between the rear fork 7 and the vehicle body frame 2. The fuel tank 10 supported above the rear part of the vehicle body frame 2, the storage box 11 supported by the vehicle body frame 2, and the seat 12 disposed on the storage box 11 , And a grab rail 13 disposed behind the seat 12, and a vehicle body cover 14 made of synthetic resin for covering the vehicle body frame 2.

  The vehicle body cover 14 includes a front cover 14A that covers the front portion of the vehicle body frame 2, a pair of left and right leg shields 14B that covers the front of the driver's feet, and a pair of left and right front side covers 14C that cover the front portion of the engine 6. A main frame top cover 14D for connecting the upper parts of the front side cover 14C, a pair of left and right rear side covers 14E for covering the lower part of the storage box 11, and a rear body cover 14F for covering the remaining part of the storage box 11 and the fuel tank 10 from both sides. The leg shield 14B, the front side cover 14C, and the main frame top cover 14D are integrally formed. A headlight 15 and a blinker 16 are disposed on the front cover 14A, a tail lamp 17 is disposed on the rear end of the rear body cover 14F, and a front fender 18 that covers the front wheel 5 is disposed on the front fork 3. ing.

  The vehicle body frame 2 includes a head pipe 20, a main frame 21 extending rearwardly downward from the head pipe 20, a pair of left and right rear frames 22 connected to a rear portion of the main frame 21 and extending rearwardly, and each rear frame. A pair of left and right pivot plates 23 joined to the front portion of 22, and a pair of left and right support frames 24 that connect each pivot plate 23 and an intermediate portion of each rear frame 22. A storage box 11, a fuel tank 10, a vehicle body cover 14, and the like are attached to the rear frame 22, and a seat 12 that can cover the storage box 11 and the fuel tank 10 from above is attached to be openable and closable. In addition, the upper portion of the rear cushion 9 is connected to the rear portion of the rear frame 22 via a rear cushion bracket 22A.

  The pivot plate 23 is connected to a rear fork 7 that supports the rear wheel 8, a main stand 30 for stopping the vehicle body in an upright state, and a side stand 31 for stopping the vehicle body in an inclined state. The front end of the rear fork 7 is rotatably supported by both pivot plates 23 via pivot bolts 7A, and is supported so as to be swingable up and down about the pivot bolts 7A.

  One end of the main stand 30 is rotatably supported by both pivot plates 23 via a pivot shaft 34 inserted at a position below the pivot bolt 7A. As shown in FIG. 2, the main stand 30 includes an insertion portion 30A through which the pivot shaft 34 is inserted, a pair of left and right foot portions 30B extending from the insertion portion 30A, and one foot portion 30B (in this example, the right side portion 30B). A stopper 30C extending from the foot) to the vehicle body center side and a footrest 30D extending from the left foot 30B are integrally provided, and the foot 30B is shown in FIG. 1 with the pivot shaft 34 as a fulcrum. It is rotatable from a rearward-facing position (corresponding to the storage position) to a downward-facing position of the vehicle body (corresponding to the stop position).

  The side stand 31 is rotatably supported on the left pivot plate 23 via a bolt 35, and FIG. 1 and 2, a pair of left and right main steps 36 on which a driver sitting on the front portion of the seat 12 puts his / her foot, a change pedal 37 and a brake pedal 38 operated by the driver, and a rear portion of the seat 12 are shown. 2 shows a pair of left and right pillion steps 39 on which a passenger sitting on the foot puts his / her foot, and the pillion steps 39 are folded to the vehicle body side.

  As shown in FIG. 1, engine hangers 40 are provided on both sides of the intermediate portion of the main frame 21, and the engine 6 is supported via the engine hangers 40 and the pivot plate 23. The engine 6 includes a crankcase 41, a cylinder block 42 connected to the front portion of the crankcase 41, a cylinder head 43 connected to the front portion of the cylinder block 42, and a head cover connected to the front portion of the cylinder head 43. 44, and a cylinder in the cylinder block 42 is a horizontal single cylinder engine (horizontal engine) arranged horizontally.

  The cylinder block 42 accommodates a piston in a reciprocating manner in a cylinder 42A. The crankcase 41 includes a crankshaft coupled to the piston via a connecting rod, an output shaft 6A of the engine 6, and a kick pedal 6B. A centrifugal clutch mechanism, a transmission mechanism, and the like that are supported and constitute a power transmission mechanism between the crankshaft and the output shaft 6A are accommodated. Power transmission from the output shaft 6A to the rear wheel 8 is performed via a chain transmission mechanism 50, that is, sprockets 51 and 52 provided on the output shaft 6A and the rear wheel 8, respectively, The power of the engine 6 is transmitted to the rear wheel 8 via the drive chain 53 wound around the 52.

  The cylinder head 43 includes an intake port 43A that communicates with the cylinder 42A and opens on the upper surface of the cylinder head 43, and an exhaust port 43B that communicates with the cylinder 42A and opens on the lower surface of the cylinder head 43. A throttle body 55 and an air cleaner 56 constituting an intake system of the engine 6 are disposed between the cylinder head 43 and the main frame 21, and the throttle body 55 is connected to the intake port 43A. An air cleaner 56 is connected to the (upstream side). Further, an exhaust unit 60 that constitutes an exhaust system of the engine 6 is connected to the exhaust port 43B.

  As shown in FIG. 2, the exhaust unit 60 includes an exhaust pipe 61, a catalyst chamber 80, and a muffler 90, and the exhaust pipe 61 forms an exhaust passage that connects the exhaust port 43 </ b> B and the muffler 90. 3A is a top view showing the exhaust pipe 61 and the catalyst chamber 80, and FIG. 3B is a side view thereof.

  As shown in FIGS. 3A and 3B, the exhaust pipe 61 includes a front exhaust pipe 62 that is a bent pipe, and a rear exhaust pipe 63 that extends substantially horizontally. As shown in FIG. 5 and FIG. 5, the bent metal tube 62 </ b> A has a distal end that is enlarged in diameter, a joint 64 is provided inside the enlarged diameter portion, and a collar 65 is provided in the enlarged diameter portion. The front exhaust pipe 62 is connected to the cylinder head 43 by pressing the collar 65 against the cylinder head 43 with a gasket (not shown) interposed therebetween, and bolting the joint 64 to the cylinder head 43 to connect to the exhaust port 43B. Communicated. As shown in FIGS. 2 and 3B, the front exhaust pipe 62 extends from the exhaust port 43B and bends in the vicinity of the cylinder head 43 so as to be within the width of the engine 6, and its rear end is a cylinder. It opens toward the vehicle body side (right side) below the head 43, and the catalyst chamber 80 is connected to the opening end. The rear exhaust pipe 63 is formed with a bent portion 63A that is bent at the rear of the catalyst chamber 80, and is disposed avoiding the drain bolt 6D fastened below the crankcase 41 of the engine 6 by the bent portion 63A.

  As shown in FIGS. 3 (A) and 3 (B), the catalyst chamber 80 includes a substantially cylindrical tubular case 81. The tubular case 81 is divided into an upper case 81A and a lower case 81B which are divided into two parts. It is formed by welding together. The cylindrical case 81 includes a side opening 82 that projects from the side and opens. The side opening 82 corresponds to one exhaust passage at the entrance / exit of the catalyst chamber 80, and the rear end of the front exhaust pipe 62 is inserted into the side opening 82 and joined by welding. The opening is directed to the exhaust port 43B of the engine 6.

At the rear end portion of the cylindrical case 81, an opening 83 that opens with a reduced diameter is provided. The opening 83 corresponds to the other exhaust passage at the entrance / exit of the catalyst chamber 80, and a small-diameter portion of the substantially truncated cone-shaped guide cap 84 is fixed from the inside of the case, and the catalyst 85 is attached to the large-diameter portion of the guide cap 84. Is fixed, and the rear exhaust pipe 63 is inserted inside the small diameter portion of the guide cap 84 and joined by welding. Since the catalyst 85 and the rear exhaust pipe 63 are arranged coaxially via the guide cap 84, the catalyst 85 is arranged along the axis of the exhaust passage of the rear exhaust pipe 63.
The cylindrical case 81 has a pair of upper and lower recesses 81C and 81D formed integrally by partially denting the upper and lower surfaces (upper case 81A and lower case 81B) of the case 81 to the inside of the case. The catalyst 85 is held from above and below by the recesses 81C and 81D.

The catalyst 85 removes hydrocarbons, carbon monoxide, nitrogen oxides, and the like in the exhaust gas by oxidizing and reducing reaction. The catalyst 85 is made of platinum, palladium, rhodium, etc. on a porous honeycomb structure. A honeycomb three-way catalyst constituted by coating is applied. The catalyst 85 is held with a predetermined gap between the inner wall (front wall and side wall) of the cylindrical case 81, and the side opening 82 opens into the longitudinal width of the catalyst 85. It is formed at a position facing the side surface of the catalyst 85.
Therefore, after the exhaust gas discharged from the engine 6 enters the catalyst chamber 80 through the front exhaust pipe 62 and flows toward the side surface of the catalyst 85 as indicated by an arrow in FIG. Then, after entering the catalyst 85 through the gap around the catalyst 85, hydrocarbons, carbon monoxide, nitrogen oxide and the like are removed by oxidation and reduction reaction, and then passed through the guide cap 84 and in the rear exhaust pipe 63. Flowing into. Instead of the honeycomb three-way catalyst, a heat tube in which platinum, palladium, rhodium or the like is supported on a punching pipe may be applied.

  In this configuration, as described above, the front exhaust pipe 62 that is a bent pipe that is bent from the exhaust port 43B and opens to the side of the vehicle body below the cylinder head 43 is connected to the side opening 82 of the catalyst chamber 80. Therefore, as shown in FIG. 1, the catalyst chamber 80 is disposed in the vicinity immediately below the cylinder 42 </ b> A. For this reason, the catalyst chamber 80 can be disposed in an empty space below the cylinder head 43 and the cylinder block 42, and the catalyst chamber 80 limits the situation where the minimum ground clearance of the vehicle is lowered and the bank angle of the vehicle. The situation can be avoided.

  The rear exhaust pipe 63 extends rearward under the engine 6 through the center of the vehicle body, then bends obliquely upward of the vehicle body behind the engine 6, and a muffler 90 is connected to the rear end thereof. In this case, since the rear exhaust pipe 63 passes through the lower part of the engine 6 within the width of the engine 6 and is connected to the muffler 90 at the rear end thereof, the rear exhaust pipe 63 can be bent little and the exhaust resistance can be lowered. The situation where the minimum ground clearance of the vehicle and the bank angle of the vehicle are limited by the exhaust pipe 63 can be avoided.

  As shown in FIGS. 1 and 2, the muffler 90 includes a cylindrical main body 100, and the cylindrical main body 100 includes a first muffler portion 91 positioned between the crankcase 41 and the rear wheel 8, and a rear wheel. And a second muffler portion 92 that extends so as to protrude to the side (right side) of 8 and a connecting portion 93 that integrally connects the muffler portions 91 and 92 with a smooth curve. ing.

6A is a plan view of the muffler 90, and FIG. 6B is a side view thereof. As shown in FIGS. 6A and 6B, the cylindrical main body 100 is formed by vertically welding two cases 100A and 100B that are vertically divided.
Stays 101 and 102 are respectively attached to the upper case 100A of the cylindrical main body 100 before and after the case 100A, and the cylindrical main body 100 is supported by the vehicle body frame 2 via the stays 101 and 102. In addition, a stopper 103 is joined to the lower case 100B by welding at a position corresponding to the lower surface of the connecting portion 93, and this stopper 103 is a stopper portion of the main stand 30 when the main stand 30 is rotated to the storage position. 30C contacts and functions as a stopper of the main stand 30.

  In the configuration described above, the muffler 90 includes the first muffler portion 91 located between the crankcase 41 and the rear wheel 8, and the second muffler portion 92 located so as to protrude from the side (right side) of the rear wheel 8. Since the muffler portions 91 and 92 are integrally connected to each other, the capacity required for the muffler 90 is distributed in the front and side of the rear wheel 8, and the crankcase 41 and the rear wheel 8 are connected to each other. Compared with the case where a muffler having the same capacity is disposed between them, it is not necessary to lengthen the wheel base, and the vehicle can be downsized.

FIG. 7A is a plan view showing the lower case 100B of the muffler 90 together with the peripheral configuration, and FIG. 7B is a side view thereof. As shown in FIGS. 7A and 7B, the lower case 100B is provided with an opening 110 that opens obliquely forward and downward in the front end wall 100B1, and the opening 110 has an opening 110 as shown in FIG. A cylindrical exhaust pipe connecting pipe 120 is attached obliquely, and a rear exhaust pipe 63 is connected to the exhaust pipe connecting pipe 120, whereby the rear exhaust pipe 63 and the exhaust pipe connecting pipe 120 communicate with each other.
As shown in FIG. 8, the exhaust pipe connection pipe 120 has a plurality of opening holes 120 </ b> A formed in the peripheral surface thereof, and the opening at the rear end thereof is blocked by a plate 120 </ b> B (see FIG. 7A). The exhaust gas discharged from the rear exhaust pipe 63 is discharged from the plurality of opening holes 120A and expanded in the chamber (expansion chamber) R1 of the first muffler portion 91, and the exhaust gas in the chamber is transferred to the second muffler portion 92. Shed.

The second muffler portion 92 is partitioned into three expansion chambers (a first expansion chamber R1A, a second expansion chamber R2, and a third expansion chamber R3 communicating with the expansion chamber R1) via the first partition wall 130 and the second partition wall 131. As shown in FIG. 7 (A), a first series pipe 132 communicating with the first expansion chamber R1A is penetrated and fixed to the first partition wall 130. The third expansion chamber R3 and the second partition wall 131 are crossed and communicated with the second expansion chamber R2.
The second communication pipe 133 is fixed to the second partition wall 131 at a position where it does not interfere with the first continuous pipe 132, more specifically, at a position shifted to the outside of the vehicle body from the first continuous pipe 132. The second communication pipe 133 communicates the second expansion chamber R2 and the third expansion chamber R3.

Further, the second partition wall 131 communicates with the third expansion chamber R3 at a position where it does not interfere with the first and second communication pipes 132 and 133, that is, a position shifted from the first series communication pipe 132 toward the vehicle body. The third communication pipe 134 passes through and is fixed, and the third communication pipe 134 passes through the rear end wall 100B2 of the lower case 100B across the second expansion chamber R2, thereby exhaust gas in the muffler 90. Is functioning as a tail pipe that discharges the gas to the outside of the muffler 90.
As shown in FIG. 7 (B), the third communication pipe 134 is inclined obliquely downward to the rear of the vehicle body, and as shown in FIG. 7 (A), the third partition pipe 134 is inclined obliquely downward to the side of the vehicle body. As shown in FIG. 9, it penetrates the rear end wall 100B2 of the lower case 100B and is fixed to the second partition wall 131 and the rear end wall 100B2 by welding. As a result, the tail pipe is disposed obliquely downward and obliquely outward with respect to the vehicle body, so that the exhaust is less involved and the contamination of the rear portion of the vehicle body due to the exhaust gas can be reduced.

Due to the muffler structure, the exhaust gas discharged from the engine 6 is purified by the catalyst chamber 80 disposed in the middle of the exhaust pipe 61, and then enters the muffler 90, as shown by an arrow in FIG. Then, after entering the expansion chamber R1 of the first muffler portion 91, enters the first expansion chamber R1A in the second muffler portion 92, enters the second expansion chamber R2 through the first communication pipe 132, and flows there. After reversing the direction and entering the third expansion chamber R3 through the second communication pipe 133, the direction of flow is reversed and discharged through the third communication pipe 134 to the outside of the muffler 90.
As described above, after the exhaust gas is expanded in the expansion chamber R1 of the first muffler portion 91, the flow of the exhaust gas is reversed in the second muffler portion 92 and expanded in the plurality of expansion chambers R2 and R3. A large muffler capacity of the first muffler portion 91 and the second muffler portion 92 can be secured, and exhaust noise can be sufficiently reduced.

  Further, the bottom shape of the second muffler portion 92 arranged on the side of the rear wheel 8 is a vehicle body right inclined surface that connects the ground contact point of the front and rear wheels and the outer lower end of the main step 36, as shown in FIGS. It is formed in an inclined shape that is inclined substantially obliquely upward from the vehicle body side (rear wheel 8 side) toward the vehicle body right side substantially along L0. Thus, it is possible to sufficiently secure the capacity of the second muffler unit 92 while avoiding the situation where the bank angle of the vehicle is limited by the second muffler unit 92 and the situation where the minimum ground clearance of the vehicle is lowered. it can.

  In the present embodiment, since the side surface opening 82 constituting one of the exhaust passages corresponding to the entrance and exit of the catalyst chamber 80 is provided on the side surface of the catalyst chamber 80, it is a bent tube that extends from the exhaust port 43B and is bent. The exhaust pipe 62 can be connected to the side opening 82, and the catalyst chamber 80 can be arranged more compactly than the arrangement in which the catalyst chamber is arranged in a straight portion of the exhaust pipe. The degree of freedom in arrangement of 80 and the degree of freedom in designing the exhaust pipe are improved. Thereby, in this structure, the catalyst chamber 80 can be compactly arranged in a space below the cylinder 42A, that is, a space below the cylinder block 42 and the cylinder head 43 and ahead of the crankcase 41.

  In addition, since the side opening 82 faces the side surface of the catalyst 85, the catalyst chamber 80 can be disposed near the cylinder head 43 (front of the engine), and the catalyst chamber 80 can be easily laid out in a space below the cylinder 42A. . Further, since the exhaust gas from the engine 6 circulates around the catalyst 85 and passes through the catalyst 85, the flow rate of the exhaust gas passing through the catalyst 85 can be suppressed. Further, since the catalyst 85 is disposed along the axis of the exhaust passage of the rear exhaust pipe 63, the catalyst chamber 80 can be reduced in size.

Further, since the side surface opening 82 of the catalyst chamber 80 is an opening toward the exhaust port 43B, the temperature of the catalyst 85 easily reaches the activation temperature due to the heat of the high-temperature exhaust gas from the exhaust port 43B. However, the catalyst 85 can be activated within a relatively short time immediately after the engine 6 is started, and water from the outside hardly enters the side opening 82, so that the catalyst 85 is not covered with water. Can be prevented.
Further, in this configuration, the cylindrical case 81 of the catalyst chamber 80 is recessed up and down to form the recesses 81C and 81D, and the catalyst 85 is held by the recesses 81C and 81D, so another fixing member for fixing the catalyst 85 The manufacturing cost can be reduced. Moreover, since the catalyst chamber 80 is formed by joining the two cases 81A and 81B vertically, the catalyst 85 can be held by joining the cases 81A and 81B, and the catalyst 85 can be easily assembled.

In the present embodiment, the muffler 90 includes a first muffler portion 91 located between the engine 6 and the rear wheel 8, and a second muffler portion 92 located so as to protrude from the side (right side) of the rear wheel 8. And a connecting portion 93 that integrally connects the muffler portions 91 and 92, the capacity required for the muffler 90 is distributed in front and side of the rear wheel 8, and there is no need to lengthen the wheel base. Thus, the vehicle can be downsized.
In addition, since the rear exhaust pipe 63 passes through the lower center of the vehicle body and bends obliquely upward of the vehicle body behind the engine 6 and is connected to the first muffler portion 91, the bending of the exhaust pipe does not increase and the exhaust pipe is processed. It is easy to ensure accuracy and exhaust resistance is reduced.

Moreover, since the muffler 90 is formed by vertically aligning the upper case 100A and the lower case 100B, the manufacture and assembly of the muffler 90 are facilitated, and the productivity is improved. In addition, since the rear exhaust pipe 63 is inserted obliquely upward from the front lower side with respect to the connection portion of the first muffler portion 91, the rear exhaust pipe 63 is not bent so that the exhaust resistance can be reduced and the rear exhaust. The pipe 63 can be connected to a position in the first muffler portion 91 that does not interfere with the weld beads (joints) of the upper and lower cases 100A and 100B.
In addition, since the stopper 103 of the main stand 30 is disposed in the connecting portion 93 that connects the first muffler portion 91 and the second muffler portion 92, the stopper 103 is a reinforcing member that reinforces the connection between the muffler portions 91 and 92. I can also serve.
Further, since the tail pipe is disposed in the second muffler portion 92 obliquely downward and obliquely outward with respect to the vehicle body, exhaust entrainment is reduced and contamination of the rear portion of the vehicle body due to exhaust gas can be reduced. .

Second Embodiment
FIG. 14 is a side view showing the catalyst chamber 180 according to the second embodiment together with the engine 6. 15A is a plan view of the exhaust pipe 161 and the catalyst chamber 180, FIG. 15B is a side view thereof, FIG. 16 is a view seen from the front, and FIG. 17 is a longitudinal sectional view. It is. In addition, the same structure as 1st Embodiment attaches | subjects the same code | symbol, and the overlapping description is abbreviate | omitted.
As shown in FIG. 14, the engine 6 includes a crankcase 41, a cylinder block 42 connected to the front portion of the crankcase 41, a cylinder head 43 connected to the front portion of the cylinder block 42, This is a horizontal single-cylinder engine (horizontal engine) that includes a head cover 44 connected to the front portion and in which the cylinders in the cylinder block 42 are horizontally arranged.

The exhaust unit 60 constituting the 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 that connects the engine 6 and the catalyst chamber 180, and a rear exhaust pipe 163 that connects the catalyst chamber 180 and the muffler 90.
The front exhaust pipe 162 is a bent pipe that is bent so as to fit within the width of the engine 6, and more specifically, as shown in FIGS. 14 and 16, the exhaust port of the cylinder chamber 43 through the exhaust port of the catalyst chamber 180. The front right side extends downward, extends rearward while bending so as to wrap around the left side of the catalyst chamber 180, and opens toward the vehicle body side (right side) below the cylinder block 42. The catalyst chamber 80 is connected to the above.

As shown in FIG. 14, the rear exhaust pipe 163 extends rearward from the rear end of the catalyst chamber 80 under the crankcase 41. As shown in FIG. 15 (B), the rear exhaust pipe 163 is formed in such a shape that its cross-sectional shape changes from a perfect circle shape to a horizontally long elliptical shape, and then returns to a perfect circle shape. The cross-sectional shape is formed in substantially the same cross-sectional area.
The reason why the cross-sectional shape of the rear exhaust pipe 163 is changed in this way is as follows.
As shown in FIG. 14, the lower surface of the crankcase 41 has a front inclined surface 41 </ b> A that is inclined rearward and downward from a connecting portion with the cylinder block 42, and a rearward direction from the lower end of the front inclined surface 41 </ b> C. It has a horizontal plane 41B that extends horizontally, and a rear inclined surface 41C that tilts backward from the rear end of the horizontal plane 41B. Under this configuration, when the entire rear exhaust pipe 163 is made into a perfect circle shape, the rear exhaust pipe is disposed below the horizontal plane 41B, which is the lowermost surface of the crankcase 41, in order to ensure a sufficient cross-sectional area of the rear exhaust pipe 163. In some cases, 163 is disposed at a position lower than the target minimum ground clearance.

  Therefore, in the rear exhaust pipe 163 of the present embodiment, the height (in the vertical direction of the vehicle body) along the inclination of the front inclined surface 41A, the horizontal surface 41B, and the rear inclined surface 41C, that is, along the inclination of the lower surface of the crankcase 41. The exhaust resistance of the rear exhaust pipe 163 is made substantially uniform by changing the shape from a perfect circular shape having substantially the same cross-sectional area to a horizontally long elliptical shape so as to change to a perfect circular shape. Sufficient minimum ground clearance can be secured while maintaining.

Next, the catalyst chamber 180 will be described in detail. As shown in FIG. 14, the catalyst chamber 180 is disposed below the cylinder block 42 and the crankcase 41 of the engine 6, and includes a catalyst housing portion 180 </ b> A for housing the catalyst 85, and the cylinder block 42 and the crank from the catalyst housing portion 180 </ b> A. A bulging portion 180B that bulges toward the engine 6 (the vehicle body upper side) along the case 41 is provided.
As shown in FIGS. 15A and 15B, the catalyst chamber 180 includes a cylindrical case 181 that integrally forms a catalyst housing portion 180A and a bulging portion 180B. The left case 181 </ b> A and the right case 181 </ b> B formed in a shape are joined to each other.

  A side opening 182 that opens in the vehicle body width direction (vehicle body left direction) is formed on the side surface of the bulging portion 180B of the cylindrical case 181, that is, on the upper side surface of the left case 181A, as shown in FIG. ing. The side opening 182 corresponds to one exhaust passage at the entrance / exit of the catalyst chamber 80. The rear end of the front exhaust pipe 162 is inserted into the side opening 182 and joined by welding.

  As shown in FIG. 17, an opening 183 that opens toward the rear is provided at the rear end of the catalyst housing portion 180A of the cylindrical case 181. The opening 183 corresponds to the other exhaust passage at the entrance / exit of the catalyst chamber 80, and the rear exhaust pipe 63 is joined to the opening 183 by welding in a state where the front end portion is inserted into the case 181. The catalyst 85 is fixed to the front end portion from inside 181. Thus, the catalyst 85 and the rear exhaust pipe 63 are arranged coaxially with the axial center of the catalyst 85 in the passage direction of the rear exhaust pipe 163, and the catalyst 85 is arranged along the axis of the exhaust passage of the rear exhaust pipe 163. In addition, the front exhaust pipe 162 can be opened within the width of the catalyst 85 in the length direction.

By the way, when the exhaust gas from the engine is discharged toward the catalyst in the catalyst chamber, the catalyst or the like may vibrate.
In contrast, in the present embodiment, as described above, the bulging portion 180B that bulges from the catalyst housing portion 180A of the catalyst chamber 180 is provided, and the front exhaust pipe 162 is connected to the side opening 182 of the bulging portion 180B. Since it is connected, the exhaust passage from the engine 6 is configured to lead to a position offset from the catalyst 85.

  Therefore, the exhaust gas from the engine 6 is not exhausted toward the catalyst 85 as shown by the wavy arrow G in FIG. 16, but is exhausted toward the inner wall 180B1 of the bulging portion 180B of the catalyst chamber 180. Then, after hitting the inner wall 180B1, it flows toward the catalyst 85 and passes through the catalyst 85. Accordingly, the exhaust gas hits the inner wall 180B1 to reduce its flow rate, and also expands in the bulging portion 180B to lower the flow rate, and then passes through the catalyst 85. Therefore, the exhaust gas flow rate through the catalyst 85 Can be reliably suppressed, and the vibration described above can be avoided.

18A is a plan view of the muffler 190, and FIG. 18B shows a side view thereof. The muffler 190 includes a cylindrical main body 200 in which cases 200A and 200B that are divided into two parts are joined vertically. The cylindrical main body 200 includes a first muffler portion 191 located between the crankcase 41 and the rear wheel 8, and a second muffler portion extending so as to project to the side (right side) of the rear wheel 8. The muffler portion 192 and a connecting portion 193 that integrally connects the muffler portions 191 and 192 with a smooth curve are provided.
Similar to the first embodiment, the muffler 190 has the same capacity between the crankcase 41 and the rear wheel 8 because the capacity required for the muffler 190 is distributed in front and side of the rear wheel 8. It is not necessary to lengthen the wheel base as compared with the case where the muffler is arranged, and the vehicle can be downsized.

FIG. 19A is a plan view showing the lower case 200B of the muffler 190 together with the peripheral configuration, and FIG. 19B is a side view thereof. A cylindrical exhaust pipe connecting pipe 120 is attached to the front portion of the lower case 200B so as to open obliquely downward to the front. A rear exhaust pipe 163 is connected to the exhaust pipe connection pipe 120, and exhaust gas exhausted from the rear exhaust pipe 163 is exhausted from the plurality of opening holes 120A to be in the expansion chamber (chamber) R1 of the first muffler section 191. The exhaust gas in the expansion chamber R1 is caused to flow to the second muffler portion 192.
The second muffler portion 192 is partitioned into three expansion chambers (a first expansion chamber R1A, a second expansion chamber R2, and a third expansion chamber R3 communicating with the expansion chamber R1) via the first partition wall 130 and the second partition wall 131. In each of the expansion chambers R1A, R2, and R3, a first communication pipe 132, a second communication pipe 133, and a third communication pipe 134 that also serves as a tail pipe are fixed.

Due to the muffler structure, the exhaust gas discharged from the engine 6 is purified by the catalyst chamber 180 and then enters the muffler 190, and as shown by the arrows in FIGS. 19A and 19B, the first muffler portion 191. After entering the expansion chamber R1, the first expansion chamber R1A in the second muffler portion 192 is entered, enters the second expansion chamber R2 through the first series of pipes 132, and the flow direction is reversed there. After entering the third expansion chamber R <b> 3 through the two communication pipes 133, the flow direction is reversed and the liquid is discharged out of the muffler 190 through the third communication pipe 134.
In this embodiment, as shown in FIGS. 19A and 19B, a plurality (three in this example) of communication pipes 132, 133, and 134 fixed to the second partition wall 131 are arranged vertically. The arrangement space of these communication pipes 132, 133, 134 can be narrowed, and the shape freedom of the muffler 190 can be improved.

  In this embodiment, since the front exhaust pipe 162 corresponding to one exhaust passage is connected to the side surface of the bulging portion 180B of the catalyst chamber 180, the exhaust passage from the engine 6 is added to the effect of the first embodiment. Can pass to a position offset from the catalyst 85 in the catalyst chamber 180, and the exhaust gas can be passed through the catalyst 85 after the flow rate is reduced in the catalyst chamber 180. Thereby, vibration of the catalyst 85 etc. can be prevented.

  Moreover, since the bulging portion 180B bulges toward the engine 6 along the cylinder block 42 and the crankcase 41, the bulging portion 180B is laid out at a dead pace between the cylinder block 42 and the crankcase 41. This can improve the layout efficiency. Further, since the front exhaust pipe 162 goes around the catalyst chamber 180 and is connected to the catalyst chamber 180, the flow of the exhaust gas can be made smooth.

As mentioned above, although this invention was demonstrated based on one Embodiment, it is clear that this invention is not limited to this. For example, the catalyst chambers 80 and 180 may be pipe products. Further, in each of the above-described embodiments, exhaust gas from the engine 6 is introduced from the side surface openings 82 and 182 of the catalyst chamber 80, and the catalyst 85 in the catalyst chambers 80 and 180 is allowed to pass through, so that the opening 83 at the rear end. Although the case of exhausting from 183 has been described, the exhaust flow may be reversed, that is, the exhaust gas of the engine 6 is introduced from the openings 83 and 183 of the catalyst chambers 80 and 180 to pass through the catalyst 85 and the side opening. You may make it discharge from the part 82. FIG.
In the above-described embodiment, the case where the present invention is applied to a motorcycle equipped with a horizontal single-cylinder engine in which cylinders are horizontally arranged has been described. It can be widely applied to motorcycles equipped with engines.

1 is a side view of a motorcycle according to a first embodiment. 1 is a top view showing a body frame of a motorcycle together with its peripheral configuration. (A) is a top view of an exhaust pipe and a catalyst chamber, (B) is the side view. FIG. 3 is a view showing a front exhaust pipe together with a catalyst chamber. It is VV sectional drawing of FIG. (A) is a top view of a muffler, (B) is the side view. (A) is a top view which shows the lower case of a muffler with a periphery structure, (B) is the side view. It is a figure which shows an exhaust pipe connecting pipe with a periphery structure. It is a figure which shows a 3rd communicating pipe with a periphery structure. It is XX sectional drawing of FIG.7 (B). It is XI-XI sectional drawing of FIG. 7 (B). It is XII-XII sectional drawing of FIG.7 (B). It is XIII-XIII sectional drawing of FIG.7 (B). It is a side view which shows the catalyst chamber which concerns on 2nd Embodiment with an engine. (A) is a top view of an exhaust pipe and a catalyst chamber, (B) is the side view. It is the figure which looked at the exhaust pipe and the catalyst chamber from the front. It is XVII-XVII sectional drawing of FIG. 15 (A). (A) is a top view of a muffler, (B) is the side view. (A) is a top view which shows the lower case of a muffler with a periphery structure, (B) is the side view.

Explanation of symbols

1 Motorcycle 2 Body frame 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 opening 83, 183 Opening 85 Catalyst 90, 190 Muffler 91, 191 First muffler part 92, 192 Second muffler part 93, 193 Connection part 103 Stopper 180A Catalyst housing part 180B Swelling part L0 Car body right inclined surface R1, R1A, R2, R3 Expansion chamber

Claims (6)

In the horizontal engine (6) in which the cylinder (42A) is horizontally disposed , the catalyst chamber (80 ) is placed in the middle of the exhaust pipe (61, 161) connecting the exhaust port (43B) of the cylinder head (43 ) and the muffler (90, 190). , 180) in the catalyst arrangement structure of the motorcycle,
A crankcase (41) of the horizontal engine (6) is disposed at the rear of the cylinder (42A) and is formed so as to bulge downward from the lower end of the cylinder. The catalyst chamber (80, 180) is Arranged in front of the crankcase (41) and below the cylinder,
Of the exhaust passages corresponding to the entrances and exits of the catalyst chamber (80, 180) , the axis of the catalyst (85) is aligned with the passage direction of one exhaust passage (83, 183) toward the muffler (90, 190) , wherein the exhaust passage of the other towards the exhaust port (43B) (82 and 182) is opened within the width in the longitudinal direction of the catalyst (85),
A front end position of the catalyst chamber (80, 180) is formed in front of a position where the other exhaust passage (82, 182) opens in a side surface of the catalyst chamber (80, 180). The catalyst arrangement structure of a motorcycle. The catalyst (85) is disposed in the catalyst chamber (80, 180) with a gap in the circumferential direction,
  The catalyst (85) is disposed along the axial center of the one exhaust passage (83, 183), and extends along the axial direction of the catalyst (85), and is connected to the muffler (90, 190). (63, 163) is connected, the other exhaust passage (82, 182) is opened in the gap, and the front exhaust pipe (62, 162) connected to the exhaust port (43B) is connected to the opening. The catalyst arrangement structure for a motorcycle according to claim 1. The catalyst arrangement structure for a motorcycle according to claim 1 or 2, wherein the catalyst (85) is held in a recess (81C, 81D) of a catalyst chamber (80). The automatic exhaust according to any one of claims 1 to 3, wherein the other exhaust passage (82, 182) is led to a position offset from the catalyst (85) in the catalyst chamber (80, 180). The catalyst arrangement structure of a motorcycle. The catalyst chamber (180) is provided with a bulge portion (180B) that bulges toward the engine side along the cylinder block (42) and the crankcase (41) of the horizontal engine (6). The catalyst arrangement structure for a motorcycle according to claim 4, wherein the other exhaust passage (182) is passed through (180B). The motorcycle according to claim 4 or 5, wherein the other exhaust passage (182) has a shape that goes around the catalyst chamber (180) and is connected to a side surface of the catalyst chamber (180). Catalyst arrangement structure.

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