JP4256370B2 - Exhaust pipe arrangement structure for motorcycles - Google Patents

Description

  The present invention relates to an exhaust pipe arrangement structure for a motorcycle.

The fuel tank is supported on a pair of left and right main frames arranged in the front-rear direction above the engine, and a down frame is arranged in front of the engine, and the exhaust is exhausted to the front of the engine so that the down frame intersects in side view. There is a motorcycle that extends a pipe and then turns back and extends backward.
Japanese Patent Publication No. 8-5419

Placement of the fuel tank is not to desirable as low as possible in order to lower the vehicle body centroid.
Therefore, the present application aims to obtain an advantageous exhaust pipe arrangement structure in a four-cycle engine vehicle.

In order to solve the above problems, an exhaust pipe arrangement structure for a motorcycle according to the present invention includes a four-cycle engine, an exhaust pipe extending from an exhaust passage of the engine, and a head pipe with the front of the engine centered on the vehicle body. In a motorcycle comprising a down tube extending obliquely downward along, and a pair of left and right radiators supported on both sides of the down tube,
The down tube includes a tapered portion formed in a tapered shape on the lower rear surface side,
The water supply hose of the radiator extends toward a water pump disposed on the side of the crankcase of the engine,
The exhaust pipe of the engine passes from the center of the front part of the cylinder head of the engine through the rear of the tapered part of the down tube, then passes under one of the radiators and bypasses the outside of the water supply hose. It extends to the rear of the vehicle body.

According to the present invention, a pair of left and right radiator water hoses supported on both sides of the down tube are extended toward a water pump arranged on the side of the crankcase of the engine, and the exhaust pipe of the engine is located below the radiator and down the tube. This is suitable for the exhaust pipe arrangement structure of a water-cooled four-cycle engine because the outside of the water supply hose is detoured through the rear of the taper-shaped portion and extended to the rear of the vehicle body.

Embodiments will be described below with reference to the drawings. FIG. 1 is a side view of an essential part of an off-road type motorcycle according to the present embodiment, FIG. 2 is a view showing the arrangement of components above the engine from the side of the vehicle body, and FIG. FIG. 4 is a view showing the layout of some parts of the upper part of the pivot plate from the side of the vehicle body, FIG. 5 is a view showing the layout of some parts from the rear of the vehicle body frame, and FIG. shows the layout of components, FIG. 7 is a fragmentary side view of the body frame, FIG. 8 is the front half section side plan view, FIG. 9 is its retrospective view, FIG. 10 is a line 10-10 sectional view of FIG. 7 .

  First, in FIG. 1, a body frame 1 forms a credor type to support a water-cooled four-cycle engine 2, a pair of left and right main frames 4 extending from the head pipe 3 to the rear through the engine 2, and the head pipe 3. A pair of left and right tubes connected to the down tube 5 that extends obliquely downward from the front of the engine 2 along the center of the vehicle body and the rear end of each of the left and right main frames 4 and arranged rearward of the engine 2 in the vertical direction Pivot plate 6 and a pair of left and right lower frames 7 that connect the lower tubes of the down tube 5 and the pivot plate 6 through the lower side of the engine 2. A pair of left and right seat rails 8 extend rearward from the upper end portion of the pivot plate 6, and the rear end portion and the intermediate portion of the pivot plate 6 are connected by an oblique rear pipe 9.

  A pair of left and right front forks 11 that are steered by a bar handle 10 are supported on the head pipe 3 via a top bridge 12 and a bottom bridge 13 so as to be rotatable. Reference numeral 14 denotes a front wheel.

A front end of the rear swing arm 16 is swingably supported by a pivot shaft 15 between intermediate portions of the left and right pivot plates 6, and a rear wheel 17 is supported at the rear end portion of the rear swing arm 16. Further, a rear cushion 19 is attached between a link 18 provided at the front portion of the rear swing arm 16 and a rear cross member described later provided at the upper end portion of the pivot plate 6 to constitute a rear wheel suspension.

  Reference numeral 20 in the figure denotes a fuel tank supported between the left and right main frames 4, 21 a seat supported on the left and right seat rails 8, 22 a radiator, 23 an exhaust pipe, 24 a carburetor, 25 An air cleaner 26 is a muffler.

  As shown in FIG. 2, the engine 2 is a water-cooled four-cycle type, the cylinder head 27 is provided substantially upright, the cylinder head cover 28 forms a substantially triangular shape in side view, and the rear side faces the inside of the main frame 4. It has entered. An exhaust passage 35 is provided in the center of the front portion of the cylinder head 27, and an exhaust pipe 23 is connected to the exhaust passage 35.

  A pair of left and right radiators 22 are supported on both sides of the down tube 5 (see FIG. 5), and a condensate-side hose 31 is piped between the upper tank 30 and the cylinder head cover 28. A water supply hose 33 extends from the lower tank 32 and is connected to the crankcase 29 side.

  Further, the carburetor 24 is connected to the intake port provided on the back side of the cylinder head 27, and the intake upstream side of the carburetor 24 is connected to the air cleaner 25 via the contube 36. The connecting tube 36 is disposed so as to cross a portion near the coupling portion with the rear end portion of the main frame 4 that is an upper portion of the pivot plate 6 of the main frame 4 in a side view.

  The connecting tube 36 is divided into a front part and a rear part at an intermediate part to form a front part 36 a and a rear part 36 b, and the rear part 36 b is integrally attached to the front surface of the air cleaner 25. The front part 36 a and the rear part 36 b can be detachably connected at the dividing position 37. Since the division position 37 is located rearward from the rear edge portion of the pivot plate 6, the front portion 36a and the rear portion 36b can be easily assembled without being blocked by the pivot plate 6, and the maintainability is improved.

  The fuel tank 20 is supported by attaching a front end portion thereof to a boss 58 positioned on the upper portion of the main frame 4 with a bracket 40 with a bolt or the like, and a rear end portion which will be described later is provided between upper end portions of the left and right pivot plates 6. It is supported on the cross member 43. A dropping portion 41 that protrudes downward is provided at the lower end of the rear end of the fuel tank 20, and a fuel cock 42 is provided below the dropping portion 41.

  The dropping part 41 is arranged to protrude into a dropping space 57a formed behind the cylinder head 27 and the cylinder head cover 28 and protruding in front of the rear cross member 43, which protrudes upward from the four-cycle engine 2, and in the longitudinal direction of the vehicle body. It is a height that overlaps with the cylinder head cover 28, and a position that overlaps the upper portion of the vaporizer 24 in a side view.

  As is clear from FIG. 4, the position of the fuel cock 42 provided below the dropping portion 41 is arranged such that the lower end thereof protrudes slightly below the lower edge of the main frame 4 in a side view, and the dropping portion 41 is The position overlaps the main frame 4. As is clear from FIG. 3, the drop-in portion 41 is provided side by side with the vaporizer 24 in the vehicle width direction.

  As shown in FIG. 1, the engine 2 is supported by the main frame 4 at the upper part, the lower part at the lower part of the down tube, the lower part at the middle part of the lower frame 7, and the crank part 29 at the rear part by the pivot shaft 15. Is done. 2 and 4, the upper portion is supported on the lower surface of the main frame 4 via the hanger bracket 39 by a support portion 38 provided at the rear portion of the cylinder head 27.

  Next, the layout of parts in the vicinity of the down tube 5 will be described. FIG. 5 is a diagram showing the down tube 5 and its neighboring parts from the front side of the vehicle body regarding the layout of the radiator 22 and the like. The radiators 22 are provided in pairs on the left and right sides, and the respective upper tanks 30 are connected by a condensate hose 31. The joint pipe 31a is connected to the water jacket outlet on the cylinder head cover 28 side.

  Further, the water supply side hose 33 coming out of each lower tank 32 extends toward the vehicle body center side, and is connected to a joint hose 34 that crosses the tapered portion 62b rearward of the down tube 5 in the left-right direction. The joint portion 34a provided is connected to a water pump 49 provided on the right side of the crankcase. In addition, the exhaust pipe 23 also extends rearward through the lower side of the radiator 22 on the right side after passing through the rear side of the tapered portion 62b and obliquely descending to the right side of the vehicle body.

  Next, the layout of components in the space 56 formed below the rear cross member 43 will be described. FIG. 6 is a view showing this part from the rear of the vehicle body. In this space, the carburetor 24 is disposed at a position below the rear cross member 43 and toward the left side of the vehicle body. A fuel cock 42 provided below the bottom is located, and a fuel tube 42 a extending downward from the fuel cock 42 is connected to the float chamber 24 a of the carburetor 24. The height of the fuel cock 42 is slightly higher than that of the float chamber 24a.

  Further, the rear cushion 19 is positioned behind these and in the vicinity of the center of the vehicle body, and the fuel cock 42 is positioned so as to overlap the front of the reserve tank 19a provided in parallel with the rear cushion 19. Further, an exhaust pipe 23 is disposed below each of the fuel cock 42 and the reserve tank 19a. The front part of the exhaust pipe 23 exits diagonally from the front part of the cylinder head 27 and then bends inward again (see FIG. 5). Thereafter, the fuel cock 42 and the inside of the right pivot plate 6 and as described above It passes through the lower part of the reserve tank 19a, and then extends rearward while turning slightly rightward and upward. Note that the contube (not shown in the figure) and the exhaust pipe 23 connected to the carburetor 24 are separately provided on the left and right sides of the rear cushion 19.

  Next, the structure of the vehicle body frame 1 will be described in detail with reference to FIGS. The main frame 4 is a member formed by extruding an aluminum alloy or the like so as to form a rectangular vertically long cross section, and its front end is welded to the head pipe 3 and its rear end is welded to the upper part of the pivot plate 6. .

  The down tube 5 is made of a square pipe made of aluminum alloy or the like, and the lower rear surface thereof is formed into a tapered shape by swaging. The rear upper surface and the lower surfaces of the middle portions of the left and right main frames 4 are viewed from the side. It is connected and reinforced by a tension pipe 50 that is substantially horizontal and has an arch shape convex forward in plan view.

  A front end portion of the tension pipe 50 is connected to the down tube 5 by a gusset 51, and a mounting stay 52 for the hanger bracket 39 is provided at a rear end portion of the tension pipe 50 and a welded portion of the main frame 4. A lower end of the down tube 5 is welded to a front end portion of a lower frame 7 made of a square pipe made of aluminum alloy or the like that is divided into left and right via a joint member 53 (see FIGS. 8 and 9).

  FIG. 10 is a transverse cross section of the down tube 5, and a rib 61 continuous in the length direction is integrally formed at the center of the inner surface of the front surface 60 among the four surfaces. The rear surface 62 has a tapered portion 62b, which will be described later, on the lower half side, and gradually decreases in the downward direction. However, the rear upper surface 62a of the upper half portion is a straight portion. In addition, a radiator mounting portion 64 having a right L-shape is welded to each outer surface of the left and right side surfaces 63, and a weld nut 65 is provided here, so that the left and right radiators 22 are bolted.

  As apparent from FIG. 7, the tapered portion 62b is provided only on the rear surface 62, and an enlarged space 57b (see FIG. 2) is formed between the rear portion and the front portion of the cylinder head 27 and the cylinder head cover 28. . In addition, the rear surface upper part 62a, the front surface 60, and the left and right side surfaces 63, which are other parts, are not tapered but are all straight surfaces. That is, the down tube 5 is formed asymmetrically in a side view due to the presence of the tapered portion 62b.

  In order to form the down tube 5 in such a shape, it is extruded as a square cross-section pipe having a predetermined cross-section so that the ribs 61 and the like are integrally formed, and swaging is performed to compress this from only four orthogonal directions. As a result, only a specific surface can be formed in a tapered shape by a necessary length. Such swaging is well known, and by doing so, a portion of the thickness can be arbitrarily deviated within one cross section, and the rib 61 of this embodiment can be easily formed.

  The pivot plate 6 is a plate-like member manufactured by casting or forging aluminum alloy or the like, and its upper end portion forms an upward extending portion 54 that protrudes upward from the rear end portion of the main frame 4, and this portion is left and right. Each is inclined inward (see FIGS. 8 and 9). Concave portions are formed on the inner facing surfaces of the left and right upper extending portions 54, and both ends of the rear cross member 43 are fitted and welded thereto. A pivot receiving portion 55 is provided at a position below the middle portion of the left and right pivot plates 6, and both ends of the pivot shaft 15 are supported here.

  The rear cross member 43 is a hollow member obtained by casting, forging, or the like of an aluminum alloy or the like, and the upper surface 44 serves as a support portion that supports the rear end portion 45 of the fuel tank 20. In addition, a cushion bracket 46 that protrudes backward in a bifurcated shape is integrally formed at the center, and an upper end 47 of the rear cushion 19 is rotatably supported by the cushion bracket 46. The cushion bracket 46 is slightly offset from the vehicle body center C, but is provided at a position where the offset is minimized. An attachment hole 46a (FIG. 4) for attaching the seat rail 8 is formed in the upper part of the cushion bracket 46.

  A space 56 (FIG. 6) sandwiched between the left and right pivot plates 6 and the lower pivot shaft 15 below the rear cross member 43 forms a very large continuous space. As described above with reference to FIG. An exhaust pipe 23 and a con tube 36 are provided. Further, a space in front of the rear cross member 43 is also formed as a large fuel tank housing space 57 (FIG. 8) that continues above the tension pipe 50 and behind the head pipe 3, and a part of the space from the cylinder head cover 28 of the engine 2. The rear side forms a space 57a behind the cylinder (FIG. 3).

  8 and 9, reference numeral 58 denotes a mounting boss of the bracket 40 formed integrally with the head pipe 3, and 59 denotes a cross part formed integrally by projecting the rear part of the head pipe 3 rearward. The joint portion of the main frame 4 is secured. In FIG. 7, reference numeral 53 a is an engine support stay provided on the joint member 53, and 7 a is an engine support stay provided on the lower frame 7.

  With the above structure, as shown in FIG. 2 and FIG. 4, a drop portion 41 that protrudes downward is provided at the lower rear portion of the fuel tank 20, so that this portion can be used as a capacity portion, and the capacity of the fuel tank 20 can be increased. It becomes. Further, even if the fuel tank 20 has a large capacity, it is not necessary to enlarge the size upward, so that the riding position and the seat 21 can be set to the front of the vehicle body. The fluctuation of the center of gravity due to movement can be reduced.

  In addition, as shown in FIGS. 3 and 6, the space 57 a on the side of the carburetor 24 can be effectively utilized by providing the drop-in portion 41 along with the carburetor 24 in the vehicle width direction. Further, since this space 57a is formed behind the cylinder head 27 and the cylinder head cover 28 and in front of the rear cross member 43, the position of the cylinder head 27 and the cylinder head cover 28 tends to increase in a 4-cycle engine. Thus, the space 57a formed in the above can be used effectively, and the arrangement is suitable for a four-cycle engine.

  Further, by providing the fuel cock 42 below the dropping portion 41, the fuel cock 42 is also provided sideways of the carburetor 24, and the fuel cock 42 also effectively utilizes the space 57a on the side of the carburetor 24. Thus, the degree of freedom of the layout can be increased, and the fuel tube 42a connected from the fuel cock 42 to the carburetor 24 can be shortened as much as possible. Piping can be done easily. Further, since the fuel cock 42 is located at the lowest position, it is difficult to cause air suction due to oil level fluctuations even when the remaining fuel is small.

  In addition, as clearly shown in FIG. 6, the space of the exhaust pipe 23 is formed as a piping portion below the fuel cock 42. Therefore, by connecting the exhaust pipe 23 below this space and the reserve tank 19a, the exhaust pipe 23 is provided. The piping can be made easy, and space can be laid out easily and efficiently.

  Moreover, as clearly shown in FIG. 4, since the lower portion of the fuel cock 42 is located in the vicinity of the lower edge of the main frame 4, the fuel cock 42 can be easily reached even if the main frame 4 has a vertically long cross section. In this embodiment, it can be easily operated from the vehicle body right side opposite to the vehicle body left side where the carburetor 24 is disposed, and maintenance can be performed without being obstructed by the presence of the carburetor 24 and the like. It will be excellent.

Next, the operation of this embodiment will be described. As shown in FIGS. 1 to 6, a water-cooled four-cycle engine 2, an exhaust pipe 23 extending from the exhaust passage of the engine 2, and a down extending obliquely downward along the center of the vehicle body from the head pipe 3 toward the front of the engine. A tube 5 and a radiator 22 supported by a pair of left and right sides of the down tube 5 are provided. A water supply hose 33 of the radiator 22 is extended toward a water pump 49 disposed on the right side of the crankcase 29 of the engine. The exhaust pipe 23 can be extended to the rear of the vehicle body by bypassing the outside of the water supply hose 33 through the lower side of the radiator 22 and behind the down tube 5.

Further, the exhaust pipe 23, again bending from bypassing the water hose 33 to the inside of the vehicle body through the inside of the pivot plate 6, it can be piped to so that extends rearwardly through the lower of the reserve tank 19a while then bends upward .

Furthermore, the down tube 5 includes a tapered portion 62b formed in a tapered shape on the lower rear surface side thereof, and the exhaust pipe 23 can be passed to the rear of the tapered portion 62b .

Further, the water supply hose 33 can be connected to a joint hose 34 that traverses the rear of the tapered portion 62 b to the left and right, and this joint hose 34 can be connected to the water pump 49 .

Side view of main part of off-road motorcycle according to this embodiment Diagram showing the arrangement of some components above the engine from the side of the vehicle body The figure which shows the planar layout of some components in the same components The figure which shows the layout of some parts in the upper part of the pivot plate from the side of the car body Diagram showing the arrangement of parts around the down tube The figure which shows the components arrangement | positioning in the space under a rear cross member Side view of the main part of the body frame The figure which shows the front half side from the upper part Lateral view Sectional view taken along line 10-10 in FIG.

Explanation of symbols

1: body frame, 2: engine, 3: head pipe, 4: main frame, 5: down tube, 6: pivot plate, 7: lower frame, 19: rear cushion, 20: fuel tank, 23: exhaust pipe, 24 : Vaporizer, 25: Air cleaner, 27: Cylinder head, 36: Con tube, 41: Dropping part, 42: Fuel cock, 43: Rear cross member, 44: Upper surface, 54: Upper extension part, 57: Fuel tank accommodation Space, 57a: space for storing the vaporizer and drop-in part

Claims (4)

A four-cycle engine, an exhaust pipe extending from the exhaust passage of the engine, a down tube extending obliquely downward along the center of the vehicle body from the head pipe, and left and right supported on both sides of the down tube In a motorcycle comprising a pair of radiators,
The down tube includes a tapered portion formed in a tapered shape on the lower rear surface side,
The water supply hose of the radiator extends toward a water pump disposed on the side of the crankcase of the engine,
The exhaust pipe of the engine passes from the center of the front part of the cylinder head of the engine through the rear of the tapered part of the down tube, then passes under one of the radiators and bypasses the outside of the water supply hose. An exhaust pipe arrangement structure for a motorcycle, characterized by extending rearward of the vehicle body. The exhaust pipe bypasses the water supply hose and then bends back to the inside of the vehicle body, passes through the inside of the pivot plate, then extends backward while bending upward, and passes below the reserve tank arranged in parallel with the rear cushion. The exhaust pipe arrangement structure for a motorcycle according to claim 1. 2. The exhaust pipe of a motorcycle according to claim 1 , wherein the water supply hose is connected to a joint hose that crosses a rear side of the tapered portion to the left and right, and the joint hose is connected to the water pump. Arrangement structure. The exhaust pipe arrangement structure for a motorcycle according to claim 1 , wherein the exhaust pipe extends rearward after extending to a position protruding outward from the radiator in a front view.

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