JP2002002573A - Intake device of engine for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake device of an engine for motorcycle capable of increasing a supercharging efficiency by preventing the pressure of traveling wind from lowering. SOLUTION: A ram air duct 44 leading traveling wind to an engine 22 is formed so as to longitudinally extend between right and left outer tubes 50 of a front fork 27 under an under bracket 51. The upstream side end of the ram air duct 44 is opened forward of a body near the lower side of the front end part of a front cowling 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for a motorcycle engine which performs supercharging by the pressure of a traveling wind.

[0002]

2. Description of the Related Art As a conventional intake device of this type, there is, for example, one configured as shown in FIGS. FIG. 10 is a side view showing a conventional intake device for a motorcycle engine, and FIG. 11 is a front view of a ram air duct.
In these drawings, reference numeral 1 denotes an on-road motorcycle, 2 denotes an engine of the motorcycle, 3 denotes front wheels, 4
Indicates a front fork. This front fork 4
Is an inverted telescopic type, and the body frame 5
Is supported by the head pipe 6 so as to be steerable. A steering handle (not shown) is attached to the front fork 4.

The engine 2 is a four-cycle multi-cylinder engine. An intake port (not shown) is opened on the upper surface (rear surface) of the cylinder 2a inclined forward, and an intake device 7 is connected to the intake port. The intake device 7 includes an intake box 8 connected to the cylinder 2 a, a ram air duct 9 for guiding traveling wind to the intake box 8, and a carburetor 10 disposed in the intake box 8. The intake box 8 is located above the engine 2 and includes two tank rails 5 a of the body frame 5.
The intake port of the carburetor 10 is opened inside. The carburetor 10 sucks air in the intake box 8 and supplies it to the engine 2 as an air-fuel mixture.

The ram air duct 9 extends from the front end of the intake box 8 toward the front of the vehicle body, and has an upstream end at a side of the left and right outer cylinders 11 of the front fork 4 in the front-rear direction of the vehicle body. It is formed to extend to. The upstream end is formed to form a pair in the vehicle width direction. As shown in FIG. 11, the upstream end is opened at the front end of the cowling 12 on the side of the outer cylinder 11.

[0005] As a conventional intake device 7 of this type, there is one in which an upstream end of a ram air duct 9 is opened at a central portion of a front end portion of a cowling 12 in a vehicle width direction. Also in the case of adopting this structure, the ram air duct 9 is guided to the engine side by bypassing the outside of the outer cylinder 11.

The conventional intake device 7 configured as described above
Means that the ram air duct 9
The traveling wind flows into the engine 2 with pressure, and the pressure (dynamic pressure) of the traveling wind is guided to the engine 2 through the intake box 8 and the carburetor 10 to perform supercharging.

[0007]

However, the conventional intake device 7 configured as described above has a problem that the supercharging efficiency during high-speed running is low. This was because the pressure of the traveling wind decreased before reaching the intake box 8. That is, when the opening at the upstream end of the ram air duct 9 is located outside the vehicle body with respect to the front fork 4, the direction in which the traveling wind flows before flowing into the intake box 8 located at the center in the vehicle width direction is changed. This is because the pressure loss is largely changed in the left-right direction, and the pressure loss increases. The opening at the upstream end of the ram air duct 9 is the cowling 12.
Also, the ram air duct 9 is bent in the vehicle width direction on the way, and the pressure loss is increased as described above.

Further, in the motorcycle employing the intake device 7 in which the opening at the upstream end of the ram air duct 9 is formed at one place in the center of the cowling 12, the cowling 12 is provided by the amount of the ram air duct 9 passing through the inside of the cowling 12. Upsizing,
There is also a problem that the front projection area increases and the CD value increases.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to prevent the pressure of the traveling wind from lowering and to improve the supercharging efficiency while preventing the CD value from increasing. It is an object of the present invention to provide a motorcycle engine intake device that can be driven.

[0010]

To achieve this object, a motorcycle engine intake device according to the present invention comprises:
The upstream end of the intake passage that guides the traveling wind to the engine extends in the front-rear direction of the vehicle body between the left and right pipe members of the front fork and below the under bracket, and also below the front end of the front cowling. It is open near the front of the vehicle body in the vicinity. According to the present invention, the traveling wind flows in a straight line from the foremost part of the vehicle body to the engine side through the central part in the vehicle width direction in both the plan view and the side view.

According to a second aspect of the present invention, there is provided an intake system for a motorcycle engine according to the first aspect of the invention, wherein at least a front fender at an upstream end of an intake passage is provided. Is formed of a flexible and elastic material.

According to the present invention, when the front fender comes into contact with the upstream end of the intake passage during braking by reducing the overall length of the front fork, the lower portion of the intake passage made of a flexible and elastic material is deformed. For this reason,
It is not necessary to reduce the passage area to avoid damage due to interference, and a desired passage area can be ensured. C
The D value does not increase. Further, by deforming the lower portion of the intake passage, the passage cross-sectional area can be temporarily reduced during braking. In addition, the material having flexibility and elasticity here is a material that has the property of being restored to its original shape when the front fender shifts to the state where it does not contact and not being deformed by running wind. Say.

According to a third aspect of the present invention, there is provided an intake device for a motorcycle engine according to the first or second aspect of the present invention, wherein the upstream end portion of the intake passage is provided. In this case, both sides of the front fork facing the pipe member are formed of a material having flexibility and elasticity.

According to the present invention, when the pipe member of the front fork rotates and comes into contact with the upstream end of the intake passage during steering, both sides of the intake passage made of a flexible and elastic material are deformed. Therefore, it is not necessary to reduce the passage area to avoid damage due to interference, and a desired passage area can be secured. The CD value does not increase. In addition, the material having flexibility and elasticity here refers to a material having such a property that the pipe member is restored to its original shape when the pipe member is brought into a non-contact state, and is not deformed by traveling wind. That means.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an intake system for a motorcycle engine according to the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view of a motorcycle equipped with an air intake device according to the present invention, and FIG. 2 is a front view of the motorcycle according to the present invention, FIG. 3 is a side view of the ram air duct, FIG. 4 is a front view thereof, and FIG. 5 is a plan view thereof. 6 is a sectional view taken along line VI-VI of the ram air duct in FIG. 3, FIG. 7 is a sectional view taken along line VII-VII of the ram air duct in FIG. 3, and FIG.
FIG. 9 is a cross-sectional view of the ram air duct taken along line VIII-VIII, and FIG. 9 is a perspective view of a radiator and an intake box.

In these figures, the one designated by the reference numeral 21 is a motorcycle according to this embodiment. This motorcycle has a water-cooled four-cycle four-cylinder engine 22 mounted between a front wheel 23 and a rear wheel 24, and has an air intake device 25 for supercharging by the pressure of traveling wind.
The motorcycle 21 includes a front cowling 26 that covers a front portion of the vehicle body.

The front wheel 23 is rotatably supported by an inverted telescopic front fork 27.
The front fork 27 is supported by a head pipe 29 of a body frame 28 so as to be steerable, and has a steering handle (not shown) attached thereto. A front fender 31 is attached to a front wheel support member 30 of the front fork 27 via a bracket (not shown). As is well known, the rear wheel 24 is supported on a vehicle body frame 28 via a rear arm (not shown) so as to be vertically swingable, and the power of the engine 22 is supplied by a chain (not shown). The structure is such that it is transmitted through the device and rotates.

The engine 22 is mounted on a vehicle body frame 28 with a cylinder 32 tilted forward. An intake port (not shown) is opened on the upper surface of the cylinder head 33 on the rear side of the vehicle body. An exhaust port (not shown) is opened on the lower surface on the front side of the. The intake device 25 is connected to the intake port, and the exhaust pipe 34 is connected to the exhaust port. The cooling water of the engine 22 is supplied to the engine 2
2 is cooled by a radiator 35 disposed in front of
The engine 22 is circulated in the engine 22 by an engine-driven cooling water pump (not shown).

The radiator 35 includes an upper radiator 36 located in front of the cylinder 32 and a crankcase 3.
7 and a lower radiator 38 located in front of the radiator 7. The upper radiator 36, as shown in FIG.
The vehicle includes a first core 36a at a central portion in the vehicle width direction, and second and third cores 36b and 36c integrally formed on both sides of the first core 36a. The second and third cores 36b and 36c are inclined so as to point toward the center in the vehicle width direction.

The intake device 25 includes a cylinder head 33
, A suction duct 42 formed integrally with the suction box 41 so as to protrude forward of the vehicle body, a carburetor 43 provided inside the suction box 41, and a front end of the suction duct 42. And a ram air duct 44 extending forward from the vehicle body. The intake box 41
Is disposed between the pair of left and right tank rails 45 of the body frame 28 and below the fuel tank 46, and has a lower end connected to the intake port forming portion of the cylinder head 33.

The carburetor 4 disposed inside the intake box 41
Reference numeral 3 denotes a so-called downdraft type, in which the intake port is opened in the intake box 41 so as to point rearward and upward. The downstream end of the vaporizer 43 communicates with the intake port. The fuel supply system of the carburetor 43 has a structure in which the fuel is pressurized by the pressure of the traveling wind, similar to that used in the conventional traveling wind supercharging type intake device. In order to pressurize the fuel with the traveling wind, a part of the traveling wind is guided from a ram air duct 44 described later to the fuel tank 46.

As shown in FIGS. 1 and 9, the intake duct 42 of the intake box 41 is formed in a rectangular tube shape, and the upper radiator extends from the center of the front end of the intake box 41 in the vehicle width direction to the front of the vehicle body. 36 extend to near the upper end. The upper radiator 36 has a concave portion 47 (see FIG. 9) that opens upward at the upper end portion of the first core 36a. The concave portion 47 has an upstream end portion of the suction duct 42, The ram air duct 44, which will be described later, can pass therethrough. By passing the suction duct 42 and the ram air duct 44 through the recess 47 of the upper radiator 36 in this manner, the heat radiation portion of the upper radiator 36 can be increased by utilizing the dead spaces formed on both sides of the intake passage.

As shown in FIGS. 3 to 5, the ram air duct 44 includes an upper duct body 48 and a lower cover 4.
9 form a rectangular tube as a whole, and extend in the front-rear direction of the vehicle body between the left and right outer cylinders 50 of the front fork 27 and below the under bracket 51. The outer cylinder 50 constitutes a pipe member of the front fork according to the present invention. As shown in FIGS. 1 and 2, the upstream end of the ram air duct 44 is opened toward the front of the vehicle body near the lower side of the front end of the front cowling 26. This ram air duct 44 constitutes the upstream end of the intake passage according to the present invention.

The ram air duct 44 according to this embodiment
The upper duct body 48 is formed of synthetic resin, the front end is fixed to the front cowling 26 with a fixing screw (not shown), and the lower cover 49 is formed of rubber and adhered to the duct body 48. . A screw hole through which the fixing screw is inserted is indicated by reference numeral 52 in FIG.
The rear end of the ram air duct 44 is inserted into the recess 47 of the upper radiator 36 from the front and connected to the suction duct 42. In order to improve the workability when connecting the ram air duct 44, a guide surface 47a (see FIG. 9) is formed in the concave portion 47. The guide surface 47a is inclined such that the opening area of the concave portion 47 gradually increases toward the front.

As shown in FIGS. 6 to 8, the lower cover 49 has a substantially U-shaped cross-section opening upward, and extends over substantially the entire length of the ram air duct 44 in the longitudinal direction. Let me. The lower cover 49 is formed of a rubber material, that is, a material having flexibility and elasticity, as described above, when the front fork 27 contracts during braking and the front fender 31 contacts the lower cover 49. This is because 49 can be easily deformed. The lower cover 49 is restored to its original shape by its own elasticity by shifting to a state where the front fender 31 does not contact. Further, the material forming the lower cover 49 is given a rigidity that does not deform under the traveling wind pressure.

Further, both sides of the lower cover 49 facing the outer cylinder 50 of the front fork 27 are extended upward so as to extend to the upper end of the ram air duct 44. This vertically extending portion is indicated by reference numeral 49a in FIGS. The vertical extending portion 49a is formed so as to cover notches 48a (see FIG. 3) formed on both sides of the duct main body 48, and forms a side wall of the intake passage in the ram air duct 44 facing the outer cylinder 50. Make up. That is, at the time of steering, the outer cylinder 50 of the front fork 27
Contact the vertical extension 49a. The adhesive portion between the duct body 48 and the lower cover 49
A structure is adopted in which the outer surface of the upper edge of the lower cover 49 overlaps the inner surface of the duct body 48.

In the intake device 25 having the ram air duct 44 configured as described above, the traveling wind flows into the upstream end of the ram air duct 44 as the vehicle body travels at high speed. The ram air duct 44 is connected to the front fork 2
7 between the two outer cylinders 50 and the under bracket 5
1, the traveling wind flowing into the upstream end of the ram air duct 44
The engine 2 passes through the center of the vehicle width direction from the front of the vehicle
It flows straight to both sides in both a plan view and a side view and flows into the suction box 41.

Therefore, according to the intake device 25,
The pressure loss of the traveling wind can be reduced, and the traveling wind flows into the intake box 41 with a high pressure. In addition, since the ram air duct 44 does not increase the front projection area of the front cowling 26, the CD value can be reduced.

The intake device 25 according to this embodiment
When the front fork 27 contracts and the front fender 31 comes into contact with the ram air duct 44 during braking, the lower cover 49 of the ram air duct 44 formed by rubber is easily deformed. The ram air duct 44 and the front fender 31 can be prevented from being damaged. Therefore, it is not necessary to reduce the passage area in order to avoid damage due to interference, and a desired passage cross-sectional area can be ensured.

Further, by deforming the lower cover 49 in this manner, the passage cross-sectional area of the intake passage can be temporarily reduced during braking, and the supercharging due to the pressure of the traveling wind can be forcibly stopped. it can. As a result, it is possible to prevent the fuel from excessively flowing out of the carburetor 43 when the vehicle is suddenly decelerated from the high-speed operation state, increase the intake resistance, and effectively use the engine brake.

Further, both sides of the ram air duct 44 facing the outer cylinder 50 of the front fork 27 (the vertically extending portions 49a of the lower cover 49) are formed of rubber. 5
When 0 rotates and comes into contact with the ram air duct 44,
The vertical extending portion 49a made of rubber is deformed. For this reason,
Damage to the ram air duct 44 by the front fork 27 during steering can be prevented. Therefore, it is not necessary to reduce the passage area in order to avoid damage due to interference, and a desired passage cross-sectional area can be ensured. The material forming the lower cover 49 is not limited to rubber, and any material having flexibility and elasticity can be used. Further, the entire ram air duct 44 may be formed of a material having flexibility and elasticity.

In this embodiment, an example in which the present invention is applied to a motorcycle using an inverted front fork has been described. However, the present invention can also be applied to a motorcycle using an upright type front fork. . Further, the intake device 25 according to the present invention is not limited to a device using the carburetor 43, and may use an injector.

[0033]

As described above, according to the present invention, the traveling wind flows straight from the frontmost portion of the vehicle body to the engine side through the central portion in the vehicle width direction in both a plan view and a side view. The pressure loss of the traveling wind can be reduced, and an intake device for a motorcycle engine with high supercharging efficiency can be realized. In addition, since the projected area of the front surface of the cowling does not increase due to the intake passage, the CD value can be reduced.

According to the second aspect of the present invention, when the entire length of the front fork is shortened during braking and the front fender comes into contact with the upstream end of the intake passage, the lower portion of the intake passage made of a flexible and elastic material. Therefore, the members forming the intake passage and the front fender are not damaged. For this reason, the intake passage can be formed so as to have a large passage cross-sectional area, and the traveling wind can flow efficiently. Also, since the lower portion of the intake passage is deformed, the passage cross-sectional area can be temporarily reduced during braking, so that it is possible to prevent supercharging with the throttle valve closed, and to reduce fuel consumption. Unnecessary increase can be prevented, and intake resistance increases, so that engine braking can be effectively used.

According to the third aspect of the present invention, when the pipe member of the front fork rotates and comes into contact with the upstream end of the intake passage during steering, both sides of the intake passage made of a flexible and elastic material. Is deformed, so that the member forming the intake passage is not damaged. For this reason, the intake passage can be formed so as to have a large passage cross-sectional area, and the traveling wind can flow efficiently.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle equipped with an intake device according to the present invention.

FIG. 2 is a front view of the motorcycle according to the present invention.

FIG. 3 is a side view of a ram air duct.

FIG. 4 is a front view of a ram air duct.

FIG. 5 is a plan view of a ram air duct.

FIG. 6 is a sectional view taken along line VI-VI of the ram air duct in FIG. 3;

FIG. 7 is a sectional view taken along line VII-VII of the ram air duct in FIG. 3;

FIG. 8 is a sectional view taken along line VIII-VIII of the ram air duct in FIG. 3;

FIG. 9 is a perspective view of a radiator and an intake box.

FIG. 10 is a side view showing a conventional intake device for a motorcycle engine.

FIG. 11 is a front view of a ram air duct.

[Explanation of symbols]

Reference numeral 21: motorcycle, 25: intake device, 27: front fork, 31: front fender, 41: intake box, 4
4. Ram air duct, 48 duct body, 49 lower cover, 50 outer cylinder, 51 under bracket.

Claims (3)

[Claims] 1. An intake system for a motorcycle engine which supercharges by the pressure of a traveling wind, wherein an upstream end of an intake passage for guiding the traveling wind to the engine is located between right and left pipe members of a front fork. An intake device for a motorcycle engine, wherein the intake device extends in the front-rear direction of the vehicle body below the under bracket and opens toward the front of the vehicle body near the lower side of the front end of the front cowling. 2. The intake device for a motorcycle engine according to claim 1, wherein at least a lower portion of the upstream end of the intake passage facing the front fender is formed of a material having flexibility and elasticity. An intake system for a motorcycle engine. 3. The intake device for a motorcycle engine according to claim 1, wherein both sides of the upstream end of the intake passage facing the pipe member of the front fork are made of a material having flexibility and elasticity. An intake device for a motorcycle engine, wherein the intake device is formed.