JP2001073759A - Motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent loss of engine output due to catalyst applied, and at the same time to curtail heat damage to the rider by enabling cooling of heat from catalyst with a simple construction. SOLUTION: This motorcycle is provided with at least downstream part of expansion part 24 of exhaust muffler 19 at side of engine and under fuel tank 10, with catalyst 26 at downstream of this expansion part 24, and with travel wind direction changing measure A for putting traveling wind W blowing at the motorcycle from front on part catalyst-placed part of expansion part 24. Travel wind direction changing measure A consists of baffle concave 34 formed at front of fuel tank 10 and baffle cover 21 covering outside of radiator 20 and fuel tank 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle mainly of an off-road type in which a catalyst is provided inside an exhaust muffler.

[0002]

2. Description of the Related Art In general, in an off-road type motorcycle, a fuel tank is installed at a front upper portion of a body frame, an engine is mounted below the fuel tank, and a seat is installed behind the fuel tank. The exhaust port of the engine is opened forward, and the exhaust muffler connected to the exhaust port is formed so as to extend forward from the exhaust port and then curve backward.

[0003] Particularly, in the case of a vehicle equipped with a two-cycle engine, the diameter of an intermediate portion of the exhaust muffler is expanded to form an expansion portion, and a catalyst is installed inside the expansion portion. The position of the catalyst in the expansion section is described in, for example, JP-A-2-1634.
As shown in JP-A-07-07, it is often on the upstream side of the expansion section. As a result, the catalyst is placed as far in front of the vehicle body as possible and is kept away from the rider's feet sitting on the seat, preventing heat damage to the rider due to the high heat generated by the catalyst and running from the front when the motorcycle is running. Wind is positively applied to the catalyst to improve the cooling of the catalyst.

[0004]

However, when the catalyst is installed on the upstream side of the expansion section of the exhaust muffler, the pulsation (reflection) of the exhaust gas inside the expansion section is weakened, and the output loss of the engine is reduced. There is a problem of being connected. On the other hand, if a catalyst is installed downstream of the expansion section, the output loss of the engine can be reduced, but since the catalyst generating high heat approaches the rider's feet, it is easy for the rider to suffer heat damage, and the cooling effect of the catalyst by running wind I can't even hope for it.

In the case of a two-cycle engine,
The engine output can be increased by increasing the length of the exhaust muffler from the exhaust port to the expansion section, but if the length of the exhaust muffler is increased in this way, more than half of the weight of the exhaust muffler including the expansion section is located on one side of the vehicle body. And the left and right weight balance of the vehicle body becomes uneven and running stability is impaired.

A motorcycle according to the present invention has been invented in order to solve the above-mentioned problems. A first object of the present invention is to avoid a loss in engine output due to the installation of a catalyst, and at the same time, to achieve a simple structure. An object of the present invention is to reduce heat damage to a rider by making it possible to cool heat generated from a catalyst.

A second object of the present invention is to improve the running stability of the motorcycle by equalizing the right and left weight balance of the exhaust muffler and to increase the overall length of the exhaust muffler to achieve a high engine output. It is in.

[0008]

In order to achieve the first object, a motorcycle according to the present invention is mounted on a front upper portion of a vehicle body frame as described in claim 1 of the appended claims. An engine is mounted below the fuel tank, an exhaust port of the engine is opened forward, and an exhaust muffler connected to the exhaust port once extends forward and then curves backward, and a diameter of an intermediate portion of the exhaust muffler is provided. Is expanded to form an expansion portion, and in a motorcycle in which a catalyst is installed inside the expansion portion, at least a downstream portion of the expansion portion is disposed beside an engine and below a fuel tank, and In addition to installing the catalyst in the downstream portion, a traveling wind diverting means is provided near the fuel tank for applying a traveling wind blown from the front at the time of traveling of the motorcycle to at least the catalyst installation portion of the expansion section.

[0009] In this case, the output loss of the engine is avoided by providing the catalyst downstream of the expansion section of the exhaust muffler. In addition, since the traveling wind is applied to at least the catalyst installation portion of the expansion section by the traveling wind diverting means, the heat generated in the expansion section by the high-temperature catalyst is cooled, and heat damage to the rider is reduced.

Also, in order to achieve the first object, a motorcycle according to the present invention has a configuration as set forth in claim 1, wherein the traveling wind direction is changed. A means for guiding the airflow, the airflow guiding recess being formed in the front of the fuel tank so as to be located immediately after the radiator installed in front of the fuel tank, and the airflow guide covering the outside of the radiator and the fuel tank. And was configured. In this case, the heat generated from the catalyst can be effectively cooled with a simple configuration using the members provided conventionally.

Further, in order to achieve the second object,
The motorcycle according to the present invention is described in claim 3.
The exhaust muffler according to claim 1, wherein the exhaust muffler extends forward from the exhaust port, and then extends to the opposite side of the inflating portion to be bent rearward. After passing through the higher position, it was bent downward again forward, and was arranged so as to cross the front of the engine to reach the expansion portion.

[0012] With this configuration, the front half and the rear half of the exhaust muffler are respectively distributed to the left and right sides and the other side of the vehicle body, so that the left and right weight balance of the exhaust muffler is equalized, and the entire exhaust muffler is constructed as a whole. The exhaust muffler can be extended accordingly, contributing to higher engine output. In addition, since the catalyst installed in the latter half of the exhaust muffler is located ahead of the rider, heat damage to the rider is eliminated.

[0013] In order to achieve the second object, the motorcycle according to the present invention, as described in claim 4, has the structure of claim 3, wherein the exhaust muffler has The rearmost part of the curved portion on the side of the engine was retracted to at least the position of the center of the crankshaft of the engine.

With this configuration, the length of the front half of the exhaust muffler from the exhaust port to just before the expansion portion, and thus the entire length of the exhaust muffler, is increased to further contribute to increasing the output of the engine. By bringing the weight close to the weight of the rear half of the exhaust muffler including the inflated portion, it is possible to contribute to equalizing the right and left weight balance of the exhaust muffler.

According to another aspect of the present invention, there is provided a motorcycle according to the present invention, wherein the exhaust muffler is provided with a catalyst. The portion is disposed on the inside in the vehicle width direction with respect to at least one of a contour extension line extending a side contour of the fuel tank downward in a front view and a wind guide cover applied to the outside of the fuel tank. With this configuration, it is difficult for the rider's feet to touch the catalyst installation part of the exhaust muffler,
Eliminates heat damage to riders.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a left side view of an off-road type motorcycle showing an application example of the present invention.

A front fork 4 for supporting a front wheel 3 is pivotally supported on a front head of a body frame 2 of the motorcycle 1 together with a handle bar 5 and the like so as to be rotatable left and right. Pivot shaft 6 installed in the width direction
, A swing arm 7 is rotatably supported vertically, and a rear wheel 8 is supported at the rear end.

A fuel tank 10 is laid over the front upper portion of the vehicle body frame 2, and an engine 11 is mounted below the fuel tank 10 and in the front half of the vehicle body frame 2. A seat 12 is provided in the rear half of the frame 2. The engine 11 is, for example, a water-cooled two-cycle single-cylinder engine. As shown in FIG. 2, a cylinder 14 is installed at a front portion of the upper surface of a crankcase 13 with a slight forward inclination. And the air cleaner 16 are sequentially connected.

An exhaust muffler 19 is provided in an exhaust port 18 (see FIG. 2) opened in front of the cylinder 14 of the engine 11.
3 and 4, a pair of left and right radiators 20 for exchanging heat of the cooling water of the engine 11 is installed in front of the fuel tank 10, as shown in FIGS.
A pair of left and right wind guide covers 21 is provided so as to cover the radiator 20 and the side surface of the fuel tank 10.

The exhaust muffler 19 is connected to the exhaust port 1.
8, a curved portion 23 having a small diameter that temporarily extends forward and curves backward, an expanding portion 24 gradually increasing in diameter following the curved portion 23, and a silencer 25 connected to the rear of the expanding portion 24.
(See FIG. 1). The expansion portion 24 is disposed such that a downstream portion thereof, that is, a tapered portion whose diameter is reduced toward the rear, extends rearward on the right side of the cylinder 14 of the engine 11 and below the fuel tank 10, A catalyst 26 is provided inside a downstream portion of the expansion section 24. The silencer 25 is disposed below the seat 12 on the right side.

As shown in FIG. 5, the catalyst 26 is provided in the expansion section 2.
4 is installed in a tapered portion on the downstream side. For example, the expansion portion 24 has a double pipe structure composed of an outer wall material 28 and an inner wall material 29, a porous punching plate is used as the inner wall material 29, and glass wool or the like is provided between the outer wall material 28 and the inner wall material 29. Of the silencer 30 is filled. The catalyst 26 is connected to a section where the inner wall material 29 is partially interrupted. The catalyst 26 has, for example, a cylindrical shape in which a catalyst body 32 having a honeycomb cross section is provided inside an outer cylinder 31, and both ends of the outer cylinder 31 are fixed to ends of the inner wall material 29 by welding or the like.

On the other hand, as shown in FIGS. 2 to 4, the curved portion 23 of the exhaust muffler 19 extends forward from the exhaust port 18 and then is located on the opposite side of the expansion portion 24, that is, on the left side of the engine 11 in this embodiment. The engine 1 curves once, further backwards, passes through a position higher than the exhaust port 18 on the left side of the engine 11, and then curves forward again downward.
1 is formed so as to reach the inflatable portion 24 while traversing rightward to the front. The rearmost portion R of the portion where the bending portion 23 bends on the left side of the engine 11 is retracted at least to the position of the crankshaft center C of the engine 11.

As shown in FIG. 3, the motorcycle 1 is provided with at least a catalyst installation portion of the exhaust muffler 19, that is, an expansion portion 24, which blows a traveling wind W blown from the front during traveling.
Is provided on the downstream side of the vehicle.
The traveling wind diverting means A includes a wind guiding recess 34 formed at the front of the fuel tank 10 so as to be located immediately after the radiator 20, and the above-described wind guiding cover 21. The shape of the air guide recess 34 is shaped so as to guide the traveling wind W blown from the front downward, and the wind guide cover 21 suppresses the traveling wind flowing downward in the air guide recess 34 from flowing to the side. It is shaped as follows. The wind guide cover 21 has an air outlet 35 for discharging a part of the traveling wind.

In the motorcycle 1 configured as described above, the exhaust gas discharged from the exhaust port 18 with the operation of the engine 11 expands through the curved portion 23 of the exhaust muffler 19 and expands in the expansion portion 24. By passing through the catalyst 26, harmful components such as HC, CO, NOx and the like are purified, and are further exhausted after being silenced sufficiently by the silencer 25. Since the catalyst 26 is installed downstream of the expansion section 24, the pulsation (reflection) of the exhaust gas in the expansion section 24 is not easily weakened, and the output loss of the engine 11 due to the installation of the catalyst 26 can be avoided. .

The temperature of the catalyst 26 rises to 700 ° C. or higher due to the contact reaction with the exhaust gas, causing the expansion portion 24 to generate heat. However, as shown in FIG. After passing through the radiator 20, the air is redirected downward by the air guiding recess 34 of the traveling wind diverting means A, and is prevented from flowing out to the side by the air guiding cover 21. To be
The heat generated by the expansion section 24 is effectively cooled, and heat damage to the rider is eliminated.

Wind guiding recess 34 constituting traveling wind diverting means A
The wind guide cover 21 is conventionally provided in this type of off-road type motorcycle for improving the cooling performance of the radiator 20, and the shape of the wind guide recess 34 is modified to exhaust the traveling wind. Since it suffices to contact the expansion portion 24 of the muffler 19, heat generation from the exhaust muffler 19 (particularly, the catalyst 26) can be effectively suppressed with a simple configuration.

As shown in FIG. 6, the exhaust muffler 1
9 by disposing the installation portion of the catalyst 26 so as to be positioned on the inner side in the vehicle width direction with respect to the contour extension line 10a which extends the side profile of the fuel tank 10 downward in a front view or the wind guide cover 21a. By preventing the rider's feet from touching the installation portion of the catalyst 26, heat damage to the rider can be more effectively suppressed.

Further, in the motorcycle 1, the curved portion 23 of the exhaust muffler 19 is once curved to the left side opposite to the expansion portion 24 disposed on the right side of the vehicle body, and the exhaust port is provided on the left side of the engine 11. 18 and is curved so that the rearmost portion R is retracted at least to the position of the center C of the crankshaft of the engine 11, and then the expansion portion 24
, The entire exhaust muffler 19 is moved toward the front of the vehicle body, and the entire length of the exhaust muffler 19, particularly the exhaust port 1
The output of the engine 11 can be increased by increasing the length of the first half from 8 to the expansion section 24.

At the same time, by increasing the length of the curved portion 23 in this manner, the weight of the curved portion 23 located on the left side of the vehicle body and the weight of the portion after the expansion portion 24 located on the right side of the vehicle body are made uniform. The running stability of the motorcycle 1 can be improved by equalizing the right and left weight balance of the exhaust muffler 19. Furthermore, since the catalyst 26 installed in the latter half (expansion part 24) of the exhaust muffler 19 is arranged ahead of the rider, heat damage to the rider due to heat generated by the catalyst 26 can be more effectively removed.

The positional relationship between the curved portion 23 and the expansion portion 24 of the exhaust muffler 19 may be reversed left and right, and the boundary between the curved portion 23 and the expansion portion 24 need not necessarily be the center in the vehicle width direction. Instead, it is only necessary that the curved portion 23 and the inflated portion 24 are provided so as to be distributed to the left and right sides of the vehicle body.

[0031]

As described above, in the motorcycle according to the present invention, at least the downstream portion of the expansion portion of the exhaust muffler is disposed on the side of the engine and below the fuel tank, and the catalyst is provided downstream of the expansion portion. And a traveling wind diverting means for applying a traveling wind blown from the front at the time of traveling of the motorcycle to at least the catalyst installation portion of the expansion section is provided near the fuel tank, whereby the engine The output loss can be avoided, and the heat generated from the expansion portion by the catalyst can be cooled by the traveling wind to reduce heat damage to the rider.

In the motorcycle according to the present invention, the traveling wind diverting means may include a wind guiding recess formed in a front portion of the fuel tank so as to be located immediately after a radiator installed in front of the fuel tank. And a wind guide cover applied to the outside of the radiator and the fuel tank, so that the heat generated from the catalyst can be effectively suppressed by a simple configuration using a conventionally provided member. be able to.

Further, in the motorcycle according to the present invention, the exhaust muffler extends forward from the exhaust port and then extends once to the opposite side of the inflating portion and curves backward.
After passing through a position higher than the exhaust port on the side of the engine, it is bent downward again forward, and it is arranged so as to reach the expansion section while crossing the front of the engine, so that the left and right weight balance of the exhaust muffler is equalized and automatic While improving the running stability of the motorcycle, the entire exhaust muffler is moved toward the front of the vehicle body, ensuring a long exhaust muffler length to achieve high engine output, and arranging the catalyst ahead of the rider to the rider. Heat damage can be removed.

Further, in the motorcycle according to the present invention, since the rearmost portion of the portion where the exhaust muffler bends on the side of the engine is retracted at least to the position of the center of the crankshaft of the engine, the front half of the exhaust muffler is provided. Extending the length further contributes to higher output of the engine, and the weight of the first half of the exhaust muffler is made equal to the weight of the second half of the exhaust muffler including the expansion section, further contributing to an even left-right weight balance of the entire exhaust muffler. can do.

[0035] In the motorcycle according to the present invention, the catalyst installation portion of the exhaust muffler is applied to a contour extension line obtained by extending a side contour of the fuel tank downward in a front view and to the outside of the fuel tank. Since at least one of the wind guide covers is disposed on the inner side in the vehicle width direction, it is possible to make it difficult for the rider's feet to touch the inflated portion of the exhaust muffler, thereby removing heat damage to the rider.

[Brief description of the drawings]

FIG. 1 is a left side view of an off-road type motorcycle showing an application example of the present invention.

FIG. 2 is a left side view of an engine and an exhaust muffler.

FIG. 3 is a right side view showing a fuel tank, an exhaust muffler, a radiator, a wind guide cover, and a traveling wind diverting unit according to the embodiment of the present invention.

FIG. 4 is a front view showing a vehicle body frame, a fuel tank, an exhaust muffler, a radiator, and a wind guide cover.

FIG. 5 is a cross-sectional view showing the installation structure of the catalyst inside the expansion section.

FIG. 6 is a front view showing an example in which the expansion portion of the exhaust muffler is arranged on the inner side in the vehicle width direction with respect to the extension of the side profile of the fuel tank and the wind guide cover.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Motorcycle 2 Body frame 10 Fuel tank 10a Extended line of contour of fuel tank 11 Engine 18 Exhaust port 19 Exhaust muffler 20 Radiator 21, 21a Wind guide cover 23 Curved portion 24 Expanded portion 26 Catalyst 34 Wind guide concave portion A Running wind turning means C Center of the crankshaft of the engine R Last part of the part where the exhaust muffler curves at the side of the engine W Running wind

Claims (5)

[Claims] An engine is mounted below a fuel tank installed at a front upper portion of a vehicle body frame, an exhaust port of the engine is opened forward, and an exhaust muffler connected to the exhaust port once extends forward. In the motorcycle in which the expansion portion is formed by expanding the diameter of the middle portion of the exhaust muffler and a catalyst is installed inside the expansion portion, at least the downstream portion of the expansion portion 24 is connected to the engine 11. , And below the fuel tank 10, the catalyst 26 is installed downstream of the expansion portion 24, and the traveling wind W blown from the front when the motorcycle is traveling.
The motorcycle is characterized in that a running wind diverting means (A) is provided in the vicinity of the fuel tank (10) so as to hit at least the catalyst installation portion of the expansion section (24). 2. A wind guiding recess 34 formed in a front part of the fuel tank 10 so as to be located immediately after a radiator 20 installed in front of the fuel tank 10; Radiator 20 and fuel tank 10
The motorcycle according to claim 1, further comprising: a wind guide cover (21) applied to an outside of the motorcycle. 3. The exhaust muffler 19 extends forward from the exhaust port 18 and then extends to the opposite side of the expansion portion 24 to bend backward, and is higher than the exhaust port 18 on the side of the engine 11. 2. The motorcycle according to claim 1, wherein the motorcycle is curved forward downward again after passing through the position, and is disposed so as to reach the expansion portion 24 while traversing the front of the engine 11. 4. The exhaust muffler 19 is provided with the engine 1
4. The motorcycle according to claim 3, wherein the rearmost portion R of the curved portion on the side of the engine 1 is retracted at least to the position of the crankshaft center C of the engine 11. 5. 5. A catalyst installation part of the exhaust muffler 19,
The vehicle is disposed inward in the vehicle width direction than at least one of a profile extension line (10a) extending downward from a side profile of the fuel tank (10) and a wind guide cover (21a) applied to the outside of the fuel tank (10). 2. The motorcycle according to 1.