Vehicle

Abstract

A motorcycle has a head pipe and an engine disposed with its cylinder axis inclined rearward. An intake pipe located between a down tube and the engine is connected to a front part of the engine and includes an engine connecting part connected to a front part of the engine. The engine connecting part is inclined upward to the front to define an acute angle with respect to the cylinder axis of the engine. A funnel is connected to a throttle body and extends upward to the front in a more vertically upward direction than an axis of the throttle body.

Description

RELATED APPLICATIONS

This application claims the benefit of priority under 35 USC 119 of Japanese patent application no. 2007-022580, filed on Feb. 1, 2007, and Japanese patent application no. 2008-003353, filed on Jan. 10, 2008, which applications are hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicle having an engine.

2. Description of Related Art

A vehicle having an engine is known. JP-A-Hei 1-115795, for example, discloses a motorcycle having an engine disposed with its cylinder axis substantially extending upward; a carburetor located between the engine and a down tube (lower frame) for supplying fuel to the engine; and a connecting part connected to a front part of the engine for coupling the engine with one end of the carburetor. Although not specified, one end of a funnel part is attached to the other end of the carburetor. Although also not specified, the connecting part is attached to the engine such that it extends substantially perpendicular to the cylinder axis in a direction that the down tube is located (in the forward direction). The funnel part sharply curves upward from the one end toward the other end thereof.

In JP-A-Hei 1-115795, because the funnel part sharply curves upward from one end toward the other end thereof, flow resistance of air that is drawn into the engine disadvantageously increases when the air passes through the funnel part to flow into the connecting part. Thus, there arises a problem of a decrease in intake efficiency of the engine. In addition, the connecting part is attached substantially perpendicular to the cylinder axis. Therefore, a longer distance is needed between the down tube and the engine in order to avoid contact between the funnel part and down tube, creating an additional problem of increased vehicle length.

SUMMARY OF THE INVENTION

The present invention solves the foregoing problems and provides a vehicle without increased length and without decreased engine intake efficiency.

A vehicle according to one aspect of the invention has a head pipe and an engine disposed with a cylinder axis thereof inclined rearward. A lower frame is located in front of the engine and extends downward from the head pipe to the rear. An intake pipe is located between the lower frame and the engine and is connected to a front part of the engine. The intake pipe includes a connecting part connected to a front part of the engine that is inclined upward to the front to define an acute angle with respect to the cylinder axis of the engine. A funnel part is connected to the connecting part and extends upward to the front in a more vertically upward direction than an axis of the connecting part.

In the vehicle according to the invention, as described above, the connecting part of the intake pipe is connected to the front part of the engine and inclines upward to the front to define an acute angle with respect to a cylinder axis of the engine, and the funnel part is connected to the connecting part and extends upward. Thus, the funnel part is not curved as sharply as in a case where the connecting part of the intake pipe is attached perpendicular to the cylinder axis of the engine, thereby allowing the funnel part to extend upward to the front. This prevents an increase in flow resistance of air drawn into the engine and passing through the funnel part, and therefore, prevents a decrease in intake efficiency of the engine. In addition, the connecting part is inclined upward to the front to define an acute angle with respect to the cylinder axis of the engine. Thus, a distance between a lower frame and the engine is shorter, compared to a case where the connecting part of the intake pipe is attached perpendicular to the cylinder axis of the engine. This prevents an increase in vehicle length.

Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, various features of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a motorcycle according to a first embodiment of the present invention.

FIG. 2 is a top plan view of the motorcycle of FIG. 1.

FIG. 3 is a side view of a portion of the motorcycle of FIG. 1.

FIG. 4 is a side view of a portion of the motorcycle of FIG. 1 showing an engine, an intake pipe, an air cleaner and surroundings.

FIG. 5 is a front sectional view of the air cleaner taken through line 100-100 of FIG. 4.

FIG. 6 is a sectional view of the engine of the motorcycle of FIG. 1.

FIG. 7 is a side view of a motorcycle according to a second embodiment of the present invention.

FIG. 8 is a side view of a portion of the motorcycle of FIG. 7 showing an engine, an intake pipe, an air cleaner and surroundings.

FIG. 9 is a sectional view of the engine of the motorcycle of FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are now described with reference to the drawings.

First Embodiment

FIGS. 1-6 illustrate a motorcycle 1 according to a first embodiment of the invention. An off-road motorcycle 1 is described as an example of the vehicle of the invention. The direction indicated by arrow FWD in the drawings is a forward traveling direction of motorcycle 1. The structure of motorcycle 1 according to the first embodiment of the invention will be described below with reference to FIGS. 1 to 6. In the following description, directions such as “left”, “right”, “forward”, “rearward”, “up” and “down” are from the perspective of a rider facing forward (in the direction of arrow FWD).

Motorcycle 1 includes a body frame 11 comprising a head pipe 2, a main frame 3, a tank rail 4, a seat rail 7, a backstay 8, a down tube 9 and a bottom frame 10. As shown in FIG. 1, left and right frames 3a and 3b (FIG. 2) of main frame 3 are connected to a connecting part 2a of head pipe 2. Frames 3a and 3b extend downward to the rear. Left and right tank rails 4a and 4b of tank rail 4 are located between a rear part of head pipe 2 and top parts of frames 3a and 3b. Tank rail 4 is an example of the “upper frame” of the present invention. As shown in FIG. 2, top rear parts of left and right frames 3a and 3b are coupled by a connecting member 5. Left rail and right rails 7a and 7b of seat rail 7 extend upward and rearward and are connected to connecting member 5 through a support 6 formed integral with connecting member 5.

Left and right stays 8a and 8b of backstay 8 are connected, respectively, between frames 3a and 3b and seat rails 7a and 7b. Down tube 9, which is an example of a “lower frame” of the present invention, extends downward and rearward from a bottom part of head pipe 2, and is located in front of engine 29. Left (10a) and right bottom frames of bottom frame 10 are located at a bottom end of down tube 9 connect down tube 9 and frames 3a and 3b.

Handlebars 12 are pivotally disposed on the top of head pipe 2. A front number plate 13 covers the front part of head pipe 2. A pair of front forks 14 are located below head pipe 2. An axle 15 is fixed to bottom ends of front forks 14. A front wheel 16 is rotatably mounted to axle 15. A front fender 17 covers an upper part of front wheel 16.

A pivot shaft 18 provided through main frame 3 supports a rear arm 19 for vertical pivotal movement. A rear wheel 21 is rotatably mounted to an axle 20 fixed to a rear end of rear arm 19. A rear fender 22 covers an upper part of rear wheel 21. As shown in FIG. 3, rear fender 22 comprises a front fender 22a and a rear fender 22b.

As shown in FIG. 1, a rear suspension 23 disposed at the rear of main frame 3 absorbs shock caused by vertical pivotal movement of rear arm 19. An upper part of the rear suspension 23 is supported by main frame 3 through support 6 (FIG. 2) of connecting member 6, while a lower part of rear suspension 23 is coupled with rear arm 19 through a coupling member 24. Footrest holding plates 25 are fixed to frames 3a and 3b.

As shown in FIG. 2, an air cleaner 26, to which a funnel 37 is connected, is located between left and right tanks rail 4a and 4b. As shown in FIG. 1, air cleaner 26 is located in front of and above engine 29. As shown in FIG. 4, air cleaner 26 includes a filter element 26a for preventing foreign matter (sand, dust, pebbles and the like) from entering an intake pipe 43; a cleaner case 26b within which filter element 26a is located; and a cover member 26c for covering cleaner case 26b from above. Filter element 26a is an example of a “filter part” of the present invention. Filter element 26a is oriented with its rear part inclined downward. Cleaner case 26b includes an upper case part 26d to which filter element 26a is fixed, and a lower case part 26e in which funnel 37 is located. An opening 26f formed in a diagonally front lower part of cover member 26c allows air to flow therein from the front (FIG. 5). Air enters from opening 26f and flows through filter element 26a into lower case part 26e of cleaner case 26b. Opening 26f is located rearward from front number plate 13 to prevent entry of foreign matter (water, pebbles and the like) into opening 26f. Further, opening 26f is located above funnel 37.

As shown in FIG. 5, filter element 26a has an overlying part 26g on top of right tank rail 4a, which lies over right tank rail 4a in the width direction. Filter element 26a also has an overlying part 26h on top of left tank rail 4b, which lies over left tank rail 4b in the width direction. In addition, filter element 26a is supported from above by a pressing member 26i located above filter element 26a. At the same time, filter element 26a is attached to extend so as not to be creased. Above pressing member 26i, a wire 26j is disposed to press filter element 26a against lower case part 26e.

A fuel tank 27 made of resin extends rearward from air cleaner 26 (FIG. 4). A center of gravity g1 of fuel tank 27 is close to a center of gravity G of the vehicle, as shown in FIG. 1. In this embodiment of the invention, the center of gravity G of the vehicle is to the rear of the center of gravity g1 of fuel tank 27. Fuel tank 27 includes an upper overlying part 27a that lies over an upper part of air cleaner 26 and a side overlying part 27b that lies over a side part of air cleaner 26.

A front part of seat 28 is located above a rear part of fuel tank 27. Seat 28 extends to the rear of fuel tank 27.

Engine 29 is located below main frame 3. Engine 29 is fixed by a support plate 30 fastened to main frame 3, a support plate 31 fastened to down tube 9, and a support plate 32 fastened to bottom frame 10. Cylinder axis L1 of engine 29 (FIG. 4) is angled rearward by approximately 5 degrees such that a center of gravity g2 of engine 29 is close to the center of gravity G of the vehicle. The center of gravity G of the vehicle is to the rear of the center of gravity g2 of engine 29.

Engine 29 includes a crankcase 29a, a cylinder 29b having a piston 33 disposed therein, a cylinder head 29c disposed above cylinder 29b and a cylinder head cover 29d (FIGS. 3 and 8). Cylinder head 29c has an intake port 29e extending forward, an exhaust port 29f extending rearward, and a combustion chamber 29g to which intake port 29e and exhaust port 29f are connected. An intake valve 34 opens or closes intake port 29e and an exhaust valve 35 opens or closes exhaust port 29f.

A throttle body 36 and funnel 37 are connected through an engine connecting part 50 to intake port 29e. Funnel 37 is made of resin and extends in a more vertically upward direction than axis L2 of throttle body 36. Engine connecting part 50 inclines upward to the front to define an acute angle with respect to cylinder axis L1 of engine 29. As shown in FIG. 6, engine connecting part 50 is connected to intake port 29e such that axis L2, which extends on the forward side (arrow FWD direction side) of engine connecting part 50, and cylinder axis L1 define an acute angle (a). Engine connecting part 50 is an example of a “connecting part” of the present invention. In addition, engine connecting part 50 inclines upward relative to a straight line L3 by an angle (b), the straight line L3 being perpendicular to cylinder axis L1 of engine 29, the angle (b) being defined by straight line L3 and axis L2 of engine connecting part 50.

A rubber member 39 is attached on one end (a downstream side) to a forward end of engine connecting part 50 using a band member 38. Rubber member 39 couples engine connecting part 50 with throttle body 36. Throttle body 36 is fixed to the other end (upstream side) of rubber member 39 using another band member 38. Throttle body 36 extends in a straight form and is inclined substantially equally to engine connecting part 50. Throttle body 36 is an example of a “connecting part” and “coupling part” of the present invention. A throttle valve 40 that adjusts the amount of air to flow through intake port 29e is disposed within throttle body 36.

A fuel injector 41 supplies fuel (gasoline) to engine 29 and is attached to throttle body 36. Fuel injector 41 is mounted on a rearward side of throttle body 36 relative to a forward side where down tube 9 is disposed. Funnel 37 supplies air flowing through air cleaner 26 to engine 29 and is fastened to throttle body 36 on its upstream side by means of a band member 42. Rubber member 39, throttle body 36 and funnel 37 form intake pipe 43. A lower part of intake pipe 43 is located between engine 29 and down tube 9. Funnel 37 is an example of a “funnel part” of the present invention.

An upstream part of intake port 29e, rubber member 39, throttle body 36 and a downstream part 37a of funnel 37 are in a straight form along an axis L2 that is inclined substantially equally to throttle body 36 (FIG. 6). Since the part of intake pipe 43 adjacent to engine 29 is in a straight form, air intake resistance is reduced, as compared to a case where the part of intake pipe 43 adjacent to engine 29 is curved or where a part of intake pipe 43 spaced apart from engine 29 is in a straight form. Performance of engine 29 is thereby improved.

Funnel 37 also includes a curved part 37b located upstream of downstream part 37a, and an upstream part 37c located upstream of curved part 37b and extending substantially right upward toward air cleaner 26 in a straight form. An axis L4 of upstream part 37c and axis L2, which is common to engine connecting part 50 and downstream part 37a of funnel 37, define an angle (c). Angle (c) is defined by axis L4 and axis L2 to be closer to 180° by angle (b) by which axis L2 is inclined upward relative to straight line L3 that is perpendicular to cylinder axis L1 of engine 29. An upper part of upstream part 37c is located within cleaner case 26b of air cleaner 26.

In the first embodiment of the invention, as shown in FIG. 4, a rear end 26k of filter element 26a of air cleaner 26 is rearward of a top end 37d of funnel 37 to create a certain gap between filter element 26a and top end 37d of funnel 37. Rear end 26k of filter element 26a is also located below top end 37d of funnel 37. In other words, filter element 26a and funnel 37 partly overlap each other in the vehicle height direction. This ensures the length of intake pipe 43 and that of funnel 37, while filter element 26a is not located not too high.

An exhaust pipe 44 is connected to exhaust port 29f formed on the rearward side of cylinder head 29c. Two screw holes 29i and recesses 29h are formed adjacent to exhaust port 29f. A connecting part 44a of exhaust pipe 44 is inserted into recess 29h. A step 44b is formed at a downstream end of connecting part 44a to attach a fixing member 45 to step 44b. Stud bolts 46 are screwed into screw holes 45a of fixing member 45 and screw holes 29i of cylinder head 29c to fasten fixing member 45 to cylinder head 29c. In this manner, exhaust pipe 44 is fixed to cylinder head 29c.

A part of exhaust pipe 44 adjacent to cylinder head 29c is substantially in a straight form, which reduces resistance of air exhausted from engine 29, as compared to a case where the part of exhaust pipe 44 adjacent to engine 29 is curved or where a part of exhaust pipe 44 spaced apart from engine 29 is in a straight form. Performance of engine 29 is thereby improved.

As shown in FIG. 3, a portion 44c of exhaust pipe 44 connected to the straight-form part adjacent to engine 29 extends upward to the rear. A coil-form part 44d connected to portion 44c extends upward to the rear and a rear part 44e downstream of coil-form part 44d extends upward to the rear. When viewed from above, coil-form part 44d is located between left and right seat rails 7a and 7b (FIG. 2). In addition, as shown in FIG. 3, coil-form part 44d is located in a region between rear suspension 23 and tire house A of rear wheel 21. A connecting part 44f of exhaust pipe 44 is connected to muffler 47 located above and behind engine 29. Muffler 47 is supported by right rail 7b (see FIG. 2) through a support plate 48. Muffler 47 is an example of a “silencer” of the present invention.

An axis of connection between exhaust pipe 44 and muffler 47 is higher than an axis of connection between exhaust pipe 44 and engine 29. Both the axes of connection between exhaust pipe 44 and muffler 47 and engine 29 are higher than rear end 29j (top surface) of cylinder 29b. All parts of exhaust pipe 44 are higher than axle 20, rear arm 19, and crankcase 29a of engine 29.

As described, in the first embodiment of the invention, intake pipe 43 is provided with engine connecting part 50 and funnel 37, engine connecting part 50 being connected to the front part of engine 29 such that it is inclined upward to the front to define acute angle (a) with respect to cylinder axis L1 of engine 29, and funnel 37 extending upward to the front. Thus, funnel 37 is not curved as sharply as in the case where engine connecting part 50 of intake pipe 43 is attached perpendicular to cylinder axis L1 of engine 29. Increase flow resistance of air drawn into engine 29 and decreased intake efficiency of engine 29 are thereby prevented. In addition, engine connecting part 50 is connected to the front part of engine 29 such that it inclines upward to the front to define acute angle (a) with respect to cylinder axis L1 of engine 29. Thus, the distance between down tube 9 and engine 29 is shorter, compared to a case where engine connecting part 50 of intake pipe 43 is attached perpendicular to cylinder axis L1 of engine 29. This prevents an increase in vehicle length. Further, funnel 37 extends in a more vertical direction than axis L2 of throttle body 36. This prevents funnel 37 from extending forward where down tube 9 is disposed, and therefore, ensures the length of intake pipe 43, while preventing the length of intake pipe 43 from increasing in the longitudinal direction. This eliminates the necessity of increasing the distance between down tube 9 and engine 29 for the purpose of avoiding contact between down tube 9 and funnel 37. Therefore, an increased length of motorcycle 1 is prevented. Intake pipe 43 can be formed longer, compared to a case where intake pipe 43 is in a straight form extending from the front part of engine 29 toward top end 37d of funnel 37. Therefore, performance of engine 29 improves particularly during low and medium-speed driving.

In addition, in the first embodiment of the invention, as described above, throttle body 36 has an inclination angle substantially equal to the inclination angle of engine connecting part 50. Flow resistance of air flowing through throttle body 36 and engine connecting part 50 is thereby reduced, as compared to a case where throttle body 36 and engine connecting part 50 are formed individually with different inclinations.

Further, in the first embodiment of the invention, as described above, the rear part of filter element 26a of air cleaner 26 is oriented with its rear part inclined downward. This prevents the rear part of filter element 26a from contacting side overlying part 27b of fuel tank 27, while allowing filter element 26a to extend rearward. Thereby, the area of filter element 26a increases.

Still further, in the first embodiment of the invention, as described above, opening 26f of air cleaner 26 is located above funnel 37. Opening 26f is thus located at an upper position apart from engine 29 or a heat source, resulting in a lower temperature of air passing from opening 26f of air cleaner 26 through intake pipe 43. Thereby, the density of air drawn into engine 29 increases, and intake efficiency of engine 29 improves.

Still further, in the first embodiment of the invention, as described above, rear end 26k of filter element 26a is rearward of top end 37d of funnel 37. Therefore, a certain gap is created between filter element 26a and top end 37d or an opening of funnel 37. This avoids a case where there is a short distance between funnel 37 and filter element 26a designed to disperse the flow of air entering from opening 26f of air cleaner 26.

Still further, in the first embodiment of the invention, as described above, rear end 26k of filter element 26a is below top end 37d of funnel 37. Therefore, filter element 26a and funnel 37 partly overlap in the vehicle height direction. The height of motorcycle 1 can thereby be smaller by an amount of the overlap between filter element 26a and funnel 37 in terms of height position.

Still further, in the first embodiment of the invention, as described above, filter element 26a has overlying parts 26g and 26h that lie over right and left tank rails 4a and 4b. The size of filter element 26a can thus be larger in the vehicle width direction by overlying parts 26g and 26h.

Second Embodiment

FIG. 7 is a side view s of a motorcycle according to a second embodiment of the present invention. FIGS. 8 and 9 illustrate the location of a funnel of the motorcycle shown in FIG. 7. The structure of an intake pipe according to the second embodiment of the present invention is described with reference to FIGS. 7-9. In the second embodiment, an upstream part 137c of a funnel 137 extends upward from throttle body 36 to the front.

In the second embodiment of the invention, as shown in FIGS. 7-9, an intake pipe 143 has funnel 137 whose upstream part 137c (FIGS. 8 and 9) is inclined forward by an angle (e). As shown in FIG. 9, an axis L10 of upstream part 137c and axis L2 of engine connecting part 50 and throttle body 36 define angle (f). Angle (f) is larger than angle (c), which is formed by axis L4 and axis L2 (FIG. 6) in the first embodiment, by an angle (e) by which upstream part 137c of funnel 137 is inclined forward. In other words, upstream part 137c of funnel 137 is formed such that axis L10 and axis L2 define angle (f) closer to 180°, compared to the first embodiment of the invention.

In the second embodiment of the invention, as shown in FIG. 9, an injector 141 is oriented such that an axis L11 of injector 141 is substantially parallel to axis L10 of upstream part 137c of funnel 137.

Other parts of the structure of the second embodiment are same as those of the first embodiment.

In the second embodiment, as described above, funnel 137 is oriented with its upstream part 137c inclined forward by angle (e). This allows upstream part 137c of funnel 137 to be formed such that axis L10 of upstream part 137c, and axis L2 of engine connecting part 50 and throttle body 36 define angle (f) to be closer to 180°. Thus, funnel 137 is not curved as much as funnel 37 in the first embodiment, and extends upward. Consequently, increased flow resistance of air drawn into engine 29 and passing through funnel 137, and decreased intake efficiency of engine 29, are prevented.

It should be understood that the embodiments disclosed herein are illustrative in all respects, and do not impose any limitation. The scope of the invention is defined by the claims rather than by the described embodiments, and includes all modifications falling within the scope of the claims and equivalents thereof.

The present invention has been described as applied to a motorcycle. However, the present invention is not limited to that, and may be applicable to other vehicles such as, for example, an automobile, a bicycle, a tricycle, and an all terrain vehicle (ATV). The invention is also not limited to an off-road motorcycle, and may be applicable to an on-road motorcycle.

Further, the engine has been described as oriented with its cylinder axis angled rearward by approximately 5 degrees. However, the present invention is not so limited, and the engine may be oriented with its cylinder axis angled rearward by more than 5 degrees.

Claims

1. A vehicle comprising: a head pipe;an engine disposed with a cylinder axis thereof inclined rearward;a lower frame located in front of the engine and extending downward from the head pipe to the rear; andan intake pipe located between the lower frame and the engine and connected to a front part of the engine, wherein the intake pipe includes:a connecting part connected to a front part of the engine and inclined upward to the front to define an acute angle with respect to a cylinder axis of the engine, anda funnel part connected to the connecting part and extending in a more vertically upward direction than an axis of the connecting part.

2. The vehicle according to claim 1, wherein the connecting part of the intake pipe includes: an engine connecting part connected to the engine; anda coupling part coupling the engine connecting part with the funnel part and having an inclination angle approximately equal to the inclination angle of the engine connecting part.

3. The vehicle according to claim 2, wherein the coupling part of the intake pipe includes a throttle valve therein.

4. The vehicle according to claim 1, wherein the funnel part of the intake pipe has an upper part that is inclined forward.

5. The vehicle according to claim 4, wherein the connecting part of the intake pipe includes: an engine connecting part connected to the engine; anda coupling part coupling the engine connecting part with the funnel part, whereinthe connecting part of the intake pipe further comprises a fuel injector mounted to the coupling part of the intake pipe for spraying fuel to the engine, wherein an axis of the fuel injector is approximately parallel to an axis of the upper part of the funnel part.

6. The vehicle according to claim 1, further comprising: an air cleaner located in front of and above the engine, to which the funnel part is connected,wherein the air cleaner includes a filter part having a rear part that is inclined downward.

7. The vehicle according to claim 6, wherein the air cleaner further includes an opening disposed above the funnel part for introducing air into the air cleaner.

8. The vehicle according to claim 6, wherein a rear end of the filter part is located rearward relative to a top end of the funnel part.

9. The vehicle according to claim 8, wherein the rear end of the filter part is lower than the top end of the funnel part.

10. The vehicle according to claim 6, further comprising an upper frame extending rearward from the head pipe,wherein the filter part has an overlying part lying over the upper frame.

11. The vehicle according to claim 1, wherein the funnel part of the intake pipe is upstream of the connecting part, and includes: a downstream part extending in a straight form;a curved part curved upward from the downstream part to the front; andan upstream part extending upward from the curved part.

12. The vehicle according to claim 11, wherein the downstream part of the funnel part of the intake pipe is connected to the connecting part.

13. The vehicle according to claim 1, wherein the vehicle is an off-road motorcycle.