Patent Application
20070277517
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
Hereinbelow, descriptions will be given as to an embodiment of the present invention with reference to the drawings. In the descriptions below, directions with respect to front, rear, right, left and the like are the same as those in the vehicle unless otherwise indicated. In the drawings, an arrow FR points to the front of the vehicle, an arrow LH points to the left-handed direction of the vehicle, and an arrow UP points to the upward direction of the vehicle.
As shown in
The rear end portions of the respective right and the left main frames 8 bend obliquely downwardly and rearwardly. The bottom end portions of the right and the left main frames 8 are connected respectively to the upper end portions of a right and left pair of pivot frames 12, which are located in the center portion of the vehicle body in the front-to-rear direction. The lower portions of the right and the left down frames 9 bend rearwardly in an underside of the front portion of the vehicle body, and then extend rearwardly substantially in a horizontal direction to form a right and left pair of lower frames 13. The rear portions of the right and the left lower frames 13 bend obliquely upwardly and rearwardly in an underside of the center portion in the front-to-rear direction of the vehicle body. Then, the rear portions of the right and the left lower frames 13 extend upwardly and rearwardly toward the bottom end portions of the corresponding right and the left pivot frames 12 to form a right and left pair of lower end frames 14. The upper end portions of the right and the left lower end frames 14 are connected to the bottom end portions of the right and the left pivot frames 12. As a result, a double-cradle type main frame portion 15 of the body frame 5 is formed.
At the rear of the main frame portion 15, a seat frame portion 16 is formed to support the rider's seat and the like. The seat frame portion 16 includes a right and left pair of seat rails 17, which extends rearwardly, respectively, from the rear portions of the right and the left main frames 8. Also included is a right and left pair of seat stays 18, which extend upwardly and rearwardly, respectively, from the rear portions of the right and the left pivot frames 12. Each of the right and the left seat rails 17 is formed in a shape of a crank with the rear portion bending upwardly when viewed from a side. The right and the left seat stays 18 support respectively the right and the left seat rails 17, with the rear end portion of each seat stay 18 being connected to the rear end portion of a corresponding one of the seat rails 17. It should be noted that the rear portions of the right and the left seat stays 18 are formed asymmetrically to each other.
A swing arm 20 is provided to support a rear wheel 19, while the front-end portion of the swing arm 20 is pivotally supported, as being capable of swinging up and down, by the right and the left pivot frames 12. An arm portion 20a, offsetted to the left, extends rearwardly and slightly downwardly, from the front-end portion (base-end portion) of the swing arm 20. At the rear end portion (tip-end portion) of the arm portion 20a, which is a cantilever-type swing arm, the rear wheel 19 is rotatably supported. The arm portion 20a is made to be a hollow member, and an unillustrated drive shaft is inserted into the inside of the arm portion 20a. The rear end portion of the arm portion 20a is configured to be a final gear case 21, where the rear end portion of the drive shaft and the rear wheel 19 are engaged with each other to allow the transmission of the drive power. A rear shock absorber 23, which slants rearwardly and downwardly, is placed between a middle portion of the arm portion 20a in the front-to-rear direction of the vehicle and a cushion support portion 22 on the left side at the rear portion of the body frame 5.
An engine 25 is mounted inside the main frame portion 15 of the body frame 5, with the crankshaft arranged along the vehicle-width (lateral) direction. The engine 25 is a two-cylinder engine of the narrow-angled V-type. A forward-leaning cylinder 27 and a rearward-leaning cylinder 28 are installed upright over a crankcase 26. A transmission case 29 is continuingly formed at the rear portion of the crankcase 26. At the output portion located on the left side of the transmission case 29, the front-end portion of the drive shaft and the engine 25 are engaged with each other as being capable of transmitting the drive power.
Intake ports 27a and 28a are respectively formed in a rear portion of the forward-leaning cylinder 27 and in a front portion of the rearward-leaning cylinder 28. An unillustrated throttle body is connected to each of the intake ports 27a and 28a. On the other hand, exhaust ports 27b and 28b are respectively formed in a front portion of the forward-leaning cylinder 27 and in a rear portion of the rearward-leaning cylinder 28. Base-end portions of a first and a second exhaust pipes 31 and 32 are respectively connected to the exhaust ports 27b and 28b. The forward-leaning- and the rearward-leaning cylinders 27 and 28 of the engine 25, as well as the intake- and the exhaust ports 27a, 28a, 27b and 28b of these cylinders are positioned inside the body frame 5 in the lateral direction.
The exhaust pipes 31 and 32, as winding appropriately, are brought below the crankcase to the right side thereof. The exhaust pipes 31 and 32 are joined together in a joint portion 33 to form a joint exhaust pipe 34. The joint exhaust pipe 34 is connected to an exhaust chamber 35, which is placed below the arm portion 20a, and between the lower end frames 14 and the rear wheel 19 when viewed from a side. Hereafter, the part that the first and the second exhaust pipes 31 and 32, the joint portion 33, the joint exhaust pipe 34 constitute is referred to as an upstream-side exhaust pipe 36.
A downstream-side exhaust pipe 37 leads out of the exhaust chamber, and is connected to a muffler 38 placed at the right side of the rear wheel 19. The exhaust chamber 35 is equipped with a catalyst 54d for exhaust-gas purification, and serves as a silencer. Use of two silencers, that is, the exhaust chamber 35 and the muffler 38, improves the sound deadening performance, while the adjustment range of the tone of the exhaust noise can be widened.
The seat frame portion 16 supports, in the front part thereof, the front seat 41a for the rider, and supports, in the rear part thereof, a pillion seat 41b for the pillion passenger. The seat height of the front seat 41a is relatively low, and the step portion between the front seat 41a and the pillion seat 41b is a backrest 41c. A step board 42 for the rider is provided on each side of the vehicle body in the front part across the crankcase 26 and the down frame 9 when viewed from a side. A pillion step holder 42a is attached to the middle portion, in the front-to-rear direction, of each of the right and left seat stays 18 to support a step for the pillion passenger. An upper-stage fuel tank 43a is placed in front of the front seat 41a, while a lower-stage fuel tank 43b is placed under the front seat 41a.
A body cover 44, made of resin, appropriately covers the vehicle body of the motorcycle 1. The body cover 44 is mainly composed of a front cowl 45, a tank cover 46, a front side cover 47, an under cover 48, and a rear side cover 49. The front cowl 45 covers the area extending from the portion in front of the head pipe 6 to both sides of the head pipe 6. The tank cover 46 is formed continuingly from the rear of the front cowl 45, and covers the upper-stage fuel tank 43a and the like. The front side cover 47 extends downwardly from the two sides of the lower portion of the front cowl 45, and covers the down frames 9 and the like. The under cover 48 covers the portion that includes the two sides of the lower portion of the engine 25. The rear side cover 49 covers the two sides of the rear portion of the seat frame portion 16.
As illustrated in
On the other hand, the second exhaust pipe 32 curves to the right at a position immediately at the rear of the exhaust port 28b. Then, the second exhaust pipe 32 extends forward passing by the right side of the two cylinders 27 and 28. Moreover, the second exhaust pipe 32, at a position located at the right side of the front-end portion of the crankcase 26, curves downwardly and rearwardly so as not to project forward beyond the down frame 9. After that, the second exhaust pipe 32 extends rearwardly as being substantially parallel to the first exhaust pipe 31 at a position obliquely upward to the right. Hereafter, in the second exhaust pipe 32, the section that curves at the right of the crankcase 26 is named a second curve section 32a.
The head end portions of the exhaust pipes 31 and 32 join together at the right of the lower portion of the crankcase 26. To this end, for example, the head end portion of the first exhaust pipe 31 bend to be connected to the head end portion of the second exhaust pipe 32. The head end portions of the two exhaust pipes 31 and 32 form the joint portion 33, and, from the single rear end portion of the joint portion 33, the joint exhaust pipe 34 extends slightly downwardly and the rearwardly and slightly diagonally inwardly in the lateral direction of the vehicle body.
To be more specific, the joint exhaust pipe 34 extends rearwardly from the rear end portion of the joint portion 33 as being in parallel to the front-to-rear direction. Then, the joint exhaust pipe 34 bends slightly downwardly to the left, inward in the lateral direction of the vehicle body, at a position immediately at the rear of the joint portion 33, and extends linearly. The joint exhaust pipe 34 then passes by immediately right side of the right lower end frame 14, with the middle section of the joint exhaust pipe 34 in the front-to-rear direction crossing the right lower end frame 14 when viewed from a side. After that, the joint exhaust pipe 34 bends further inwardly in the lateral direction of the vehicle body at a point at the right of the exhaust chamber 35 to be obliquely connected to the right end portion of the exhaust chamber 35. Hereafter, in the joint exhaust pipe 34, the section bending at a position immediately at the rear of the joint portion 33 is named a front-side bending portion 34a, while the section bending at a position at the right of the exhaust chamber 35 is named a rear-side bending portion 34b. As described above, the joint exhaust pipe 34 bends at a plurality of positions (specifically, at two positions), and is connected obliquely to the exhaust chamber 35. As a result, the bending of the joint exhaust pipe 34 is made moderate to lessen the resistance to the exhaust-gas flow.
As illustrated in
The exhaust chamber is formed in a flattened shape with its vertical width being made smaller than the horizontal width. The exhaust chamber 35 slightly slants downwardly to the rear, so that the upper face of the exhaust chamber 35 also slightly slants downwardly to the rear. The front portion of the swing arm 20, which also slightly slants downwardly to the rear, is positioned over the exhaust chamber 35. Since the upper face of the exhaust chamber 35 slants as being substantially parallel to the swing arm 20, the space needed for the up-and-down movements of the swing arm 20 can be easily secured.
In the exhaust chamber 35, the apex at the bottom in the cross-sectional shape, which apex forms the lower end portion of the exhaust chamber 35, is chamfered in a circular-arc shape that is gentler than the shapes of other apexes. The exhaust chamber 35 faces the ground between the front and the rear wheel of the vehicle body. By chamfering the lower end portion of the exhaust chamber 35, the ground clearance corresponding to this section can be easily secured. It should be noted that a metal plate 35d is fixed by fixation means such as rivets to an area around the bottom end portion of the exhaust chamber 35.
A supporting stay 35e is provided in the front-end portion of the exhaust chamber 35 as sticking forward out at the middle in the lateral direction. With this supporting stay 35e, the front portion of the exhaust chamber 35 is supported by a lower cross member 14a that bridges the right and the left lower end frames 14 in the body frame 5.
A water-cooling type oil cooler 26a has a cylindrical-shape and extends along the front-to-rear direction and is provided to the lower rear end portion of the crankcase 26 (transmission case 29). To the rear end of the oil cooler 26a, a cartridge-type oil filter 26b with a cylindrical shape that is substantially coaxial with the oil cooler 26a is detachably attached. The oil filter 26b is positioned in front of the exhaust chamber 35, but a space is secured in between to use when the oil filter 26b is attached or detached.
The exhaust chamber 35 is placed as being slightly shifted to the left of the vehicle body. More specifically, the left-hand end portion of the exhaust chamber 35 is positioned substantially in line with the left lower frame 13 in the lateral direction, while the right-hand end portion of the exhaust chamber 35 is located at an inner position in the lateral direction of the vehicle body than the right lower frame 13.
An exhaust-gas inlet 51 and an exhaust-gas outlet 52 are formed in the right-hand end portion (right-hand lid member 35c) of the exhaust chamber 35. The joint exhaust pipe 34 is connected to the exhaust-gas inlet 51, while the downstream-side exhaust pipe 37 leads out from the exhaust-gas outlet 52. In other words, the exhaust-gas inlet 51 and the exhaust-gas outlet 52 are located at inner positions in the lateral direction of the vehicle body than the right lower frame 13.
On the other hand, the exhaust-gas outlet 52 is positioned in an upper front portion of the exhaust chamber 35 in a position anterior to and superior to the exhaust-gas inlet 51.
Here, the exhaust chamber 35 is positioned at the rear of the engine 25 when viewed from a side of the vehicle body. The muffler 38 is positioned at the rear of the exhaust chamber 35 with the exhaust port 38a at the rear end portion thereof. The upstream-side exhaust pipe 36 is positioned between the engine 25 and the exhaust chamber 35, while the downstream-side exhaust pipe 37 is positioned between the exhaust chamber 35 and the muffler 38 (exhaust port 38a). The exhaust gas produced in the engine 25 passes through the upstream-side exhaust pipe 36, the exhaust chamber 35, and the downstream-side exhaust pipe 37 to reach the muffler 38, and then is discharged to the air from the exhaust port 38a.
The exhaust-gas outlet 52 is positioned in a side closer to the engine 25 (in the front side) of the exhaust chamber 35, that is, in a side farther from the exhaust port 38a. Meanwhile, the exhaust-gas inlet 51 is positioned in a side closer to the exhaust port 38a (in the rear side) than the exhaust-gas outlet 52 is, that is, in a side farther from the engine 25 than the exhaust-gas outlet 52 is positioned. With this configuration, the exhaust pipes 36 and 37 are made longer in comparison to a case with a configuration wherein the exhaust-gas inlet 51 is positioned in the front side with the exhaust-gas outlet 52 being positioned in the rear side.
To the exhaust-gas outlet 52, the upstream-side end portion of the downstream-side exhaust pipe 37 is connected from a position behind the exhaust-gas outlet 52 on the right obliquely with respect to the axial line of the chamber C1.
The downstream-side exhaust pipe 37 extends out from the exhaust-gas outlet 52 slightly obliquely, and then bends and extends further rearwardly at a position immediately above the joint exhaust pipe 34. In other words, at a position where the downstream-side exhaust pipe 37 crosses the joint exhaust pipe 34 when viewed from the bottom of the vehicle body. Eventually, the downstream-side end portion of the downstream-side exhaust pipe 37 is connected to the front-end portion of the muffler 38. In other words, the downstream-side exhaust pipe 37, as a whole, extends from the exhaust-gas outlet 52 obliquely rearwardly to the right, that is, to a side away from the exhaust ports 27b and 28b of the engine 25. Thereafter, in the downstream-side exhaust pipe 37, the section that bends at the position above the joint exhaust pipe 34 is named a downstream-side bending section 37a. The downstream-side bending section 37a substantially lies over the rear-side bending portion 34b of the joint exhaust pipe 34 when viewed from the bottom of the vehicle body.
The exhaust chamber 35 is divided, by a partition wall 53 that is substantially orthogonal to the exhaust chamber in the lateral direction, into a left and a right expansion chambers 53a and 53b. First, second, and third communication pipes 54a, 54b and 54c are provided inside the exhaust chamber 35. The first communication pipe 54a extends from the exhaust-gas inlet 51 to the left, and penetrates the partition wall 53 to allow communication between the exhaust-gas inlet 51 and the left-hand expansion chamber 53a. The second communication pipe 54b penetrates the partition wall 53 at a position anterior to the position where the first communication pipe 54a penetrates the partition wall 53. The second communication pipe 54b thus allows the communication between the left and the right expansion chambers 53a and 53b. The third communication pipe 54c extends from the exhaust-gas outlet 52 to the right and allows communication between the right expansion chamber 53b and the exhaust-gas outlet 52. Each of the communication pipes 54a, 54b, and 54c are arranged substantially in parallel to the direction of the axial line of the chamber C1 (lateral direction). A catalyst 54d for exhaust-gas purification is provided inside each of the first and the third communication pipes 54a and 54c.
It should be noted that the exhaust chamber 35 may be formed without the partition wall 53 as shown in
The muffler 38 extends in the front-to-rear direction slightly upwardly and rearwardly while the cross-sectional shapes are substantially constant. The muffler 38 is placed as substantially lying over the rear portion of the swing arm 20 when viewed from a side of the vehicle body. Hereafter, the axial line along the extending direction of the muffler 38 is represented by C2. Each of the cross-sectional shapes of the muffler 38 is a triangular shape. The sides of the triangular are composed of an upper face that extends substantially along the lateral direction, an inner side face that extends substantially along the vertical direction, and a slant face that extends from the right-hand end of the upper face to the bottom end of the inner side face. With this shape, a larger bank angle is secured on the right-hand side of the vehicle body. The middle portion in the front-to-rear direction of the muffler 38 is supported by a right-hand pillion step holder 42a, which serves as a muffler stay.
In the upper right side of the front-end portion of the muffler 38, a protruding portion 55a is formed in a funnel shape that projects and is tapered forward from the front-end portion. At the tip end portion of the protruding portion 55a, an exhaust-gas inlet 55 is formed as an opening directed obliquely toward the left to the front. To the exhaust-gas inlet 55, the downstream-side end portion of the downstream-side exhaust pipe 37 is connected from a position ahead of the exhaust-gas inlet 55 on the left obliquely with respect to the axial line of the muffler C2.
As described above, the exhaust-gas inlet 55 of the muffler 38 is positioned on the right side, on the outer side in the lateral direction of the vehicle body. Accordingly, the exhaust-gas inlet 55 is positioned away from the exhaust-gas outlet 52 of the exhaust chamber 35 which is positioned at the left side of, at the inner side in the lateral direction of the vehicle body than, the muffler 38. As a result, the downstream-side exhaust pipe 37 is elongated with compare to a case in which the exhaust-gas inlet 55 is positioned on the left side.
As described before, the joint exhaust pipe 34 is obliquely connected to the exhaust chamber 35. Accordingly, a space where some component parts can be placed is produced at the right side of the rear portion of the exhaust chamber 35. By utilizing the space, the front-end portion of the muffler 38 extends so as to overlap the rear portion of the exhaust chamber 35 when viewed from a side of the vehicle body. As a result, the volume of the muffler 38 as a whole is increased to improve the sound deadening performance.
In addition, the middle section of the upstream-side exhaust pipe 36, the section of each of the first and the second exhaust pipes 31 and 32, respectively further downstream from the curve portions 31a and 31b to the middle section in the front-to-rear direction of the joint exhaust pipe 34, is formed as winding to the outer side of the vehicle body in the lateral direction than the body frame 5, the right down frame 9, the right lower frame 13, the right lower end frame 14. Since the upstream-side exhaust pipe 36 curves as being convex outward in the lateral direction of the vehicle body, the upstream-side exhaust pipe 36 can be elongated.
A section of the joint exhaust pipe 34 on the further downstream side than the front-side bending portion 34a is an inward diagonal section 56 in which the pipe goes inward in the lateral direction of the vehicle body as the pipe goes down the stream (rearwardly) of the exhaust gas. On the other hand, the downstream-side exhaust pipe 37 in this embodiment, as a whole, is an outward diagonal section 57 in which the pipe goes outwardly in the lateral direction of the vehicle body as the pipe goes down the stream (rearwardly) of the exhaust gas. These diagonal sections 56 and 57 are placed as crossing each other when viewed from the bottom of the vehicle body at a position substantially below the seat position of the front seat 41a when viewed from a side of the vehicle body. The widths of parts of the respective diagonal sections 56 and 57, which parts are located outside the vehicle body in the lateral direction, are made minimum at a crossing portion 58 where the diagonal sections cross each other when viewed from the bottom of the vehicle body. With this structure, a larger space on which the rider places his/her foot when the rider is seated on the front seat 41a or when the rider climbs on the motorcycle, can be secured directly below the front seat 41a and near the vehicle body.
Inside the joint exhaust pipe 34, an oxygen-concentration sensor (O2 sensor) 59 is provided between the rear-side bending portion 34b and the exhaust-gas inlet 51 to detect the oxygen concentration of the exhaust gas. The oxygen-concentration sensor 59 is placed with its detection unit facing the inside of the joint exhaust pipe 34 from above. The upwardly protruding portion of the oxygen-concentration sensor 59 from the joint exhaust pipe 34 is surrounded by the downstream-side exhaust pipe 37 from the front side and the right side of the protruding portion. The exhaust chamber 35 is positioned at the left side of the protruding portion, while the muffler 38 is positioned at the rear side of the protruding portion. With this structure, the oxygen-concentration sensor 59 is better protected, and becomes more easily heated to reach swiftly the activation temperature.
As has been described thus far, the exhaust pipe structure in the above-described embodiment includes the engine 25 supported by the body frame 5 and the upstream-side exhaust pipe 36 connected to the exhaust ports 27b and 28b of the engine 25. Also included in the exhaust pipe structure is the exhaust chamber 35 which has the exhaust-gas inlet 51 and the exhaust-gas outlet 52, and in which the upstream-side exhaust pipe 36 is connected to the exhaust-gas inlet 51. The exhaust pipe structure additionally includes the downstream-side exhaust pipe 37 which is connected to the exhaust-gas outlet 52, and which extends in a direction to move away from the exhaust ports 27b and 28b. The exhaust-gas inlet 51 is formed at a position farther away from the exhaust ports 27b and 28b than the exhaust-gas outlet 52 is positioned.
According to this configuration, the lengths of the upstream-side and the downstream-side exhaust pipes 36 and 37 can be made longer, in comparison to the case in which the exhaust-gas inlet 51 is placed closer to the exhaust ports 27b and 28b than the exhaust-gas outlet 52 is positioned. Meanwhile, the length of the exhaust pipe structure as a whole in the front-to-rear direction is restricted. As a result, the adjustment range for engine characteristics can be widened. For example, the kind of engine characteristics in which the change in engine power is made to depend linearly on the throttle-opening angle, can be made easily reproducible. This is particularly preferable in a V-type two-cylinder engine. This is because it is more effective in such an engine to elongate the distance between the joint portion 33 of the two exhaust pipes respectively from the cylinders 27 and 28 and the exhaust chamber 35 located at the downstream side from the joint portion 33, more specifically, the length of the joint exhaust pipe 34.
In addition, in the above-described exhaust pipe structure, the body frame 5 includes the head pipe 6 with the right and left pair of down frames 9 extending obliquely downwardly and rearwardly from the head pipe 6. Each lower frame 13 is provided as extending rearwardly from the bottom end of each down frame 9. Each lower end frame 14 is provided as extending obliquely upwardly and rearwardly from the rear end of each lower frame 13. The exhaust chamber 35 is placed at the rear of the lower end frames 14 when viewed from a side of the vehicle. Accordingly, the space at the rear of the lower end frames 14 extending obliquely upwardly and rearwardly can be effectively utilized as a space where the exhaust chamber 35 is placed. As a result, a sufficient volume of the exhaust chamber 35 can be secured.
Moreover, in the above-described exhaust pipe structure, the exhaust ports 27b and 28b as well as the exhaust-gas inlet 51 are placed inside the body frame 5 in the lateral direction, while the middle section of the upstream-side exhaust pipe 36 is made to be located outside of the body frame 5 in the lateral direction. Accordingly, the upstream-side exhaust pipe 36 can be made to curve as being convex outwardly of the vehicle body. As a result, the adjustment range for engine characteristics can be widened.
Furthermore, in the above-described exhaust pipe structure, the upstream-side exhaust pipe 36 includes the inward diagonal section 56 in which the pipe goes inward in the lateral direction of the vehicle body as the pipe goes down the stream of the exhaust gas. Meanwhile, the downstream-side exhaust pipe 37 includes the outward diagonal section 57 in which the pipe goes outward in the lateral direction of the vehicle body as the pipe goes down the stream of the exhaust gas. The inward diagonal section 56 and the outward diagonal section 57 cross each other when viewed from the bottom of the vehicle body at a position below the front seat 41a supported by the body frame 5. Accordingly, the projection, outside of the vehicle body, of the upstream-side and the downstream-side exhaust pipes 36 and 37 is made small in the crossing portion 58 of the inward diagonal section 56 and the outward diagonal section 57 when viewed from the bottom of the vehicle body. As a result, the rider can plant his/her foot more easily on the ground by widening the space on which the rider can place his/her foot below the front seat 41a.
It should be noted that the present invention is not limited to the above-described embodiment. The present invention can be applied, for example, to a single-cylinder engine or to various types of in-line engines. In addition, the present invention can be applied to a three-wheel, or a four-wheel vehicle. Moreover, the present invention can be carried out with the exhaust chamber 35 being the only silencer that the vehicle has. Furthermore, the present invention can have a configuration in which a part of the downstream-side exhaust pipe 37 is made to be the outward diagonal section 57.
The configuration in the above-described embodiment is only an example of the present invention. It is obvious that various changes may be made without departing from the scope of the invention.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-151206 | May 2006 | JP | national |
