JPH10331733A - Intake device for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the intake device of a motor cycle to eliminate an influence by a dynamic pressure by converting the dynamic pressure of running air into a static pressure and stably increase an intake air amount by reducing intake resistance. SOLUTION: An approximately closed box 24 having a volume enough to allow conversion of a dynamic pressure into a static pressure is disposed between an engine unit arranged in the rear of a front wheel and a fuel tank disposed above the engine unit. An introduction region 24d wherein outside air is introduced in a box 24 and a suction region 24c wherein air in the box 24 is sucked in an engine are communicably partitioned. The intake port 13a of an engine is positioned in the suction region 24c, and the rear end opening 25a of an outside introduction duct 25 is connected. The opening 25d of the front end of the outside air introduction duct 25 is positioned in front of an engine, the outside air introduction duct 25 is formed in a taper-form state wherein diameter is gradually decreased from a rear end opening 25a to a front end opening 25d, and a taper angle is set to 10 deg. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle air intake system capable of increasing the amount of air taken into an engine by the pressure of a traveling wind.

[0002]

2. Description of the Related Art As an intake device that utilizes the pressure of a running wind to increase the amount of intake air of an engine, for example, a relatively large-diameter outside air introduction duct is disposed substantially horizontally on the side of a vehicle body. In some cases, a front end opening of a duct is located on a side of a front fork and a side of a front wheel, and a rear end opening communicates with an intake port formed on a side of an engine.

[0003]

In [0005] However the intake system, traveling wind dynamic pressure (= ρv ^2/2: ρ is the fluid density,
v is easily affected by flow velocity) and pipe loss (intake resistance)
Therefore, there is a problem that it is difficult to stably increase the intake air amount.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and can convert the dynamic pressure of traveling wind to static pressure to eliminate the influence of the dynamic pressure. It is an object of the present invention to provide a motorcycle intake device that can be stably increased.

[0005]

According to a first aspect of the present invention, a front end opening of an outside air introduction duct for introducing outside air is positioned forward of the engine, and a rear end opening of the outside air introduction duct communicates with an intake port of the engine. In a motorcycle intake device, a substantially hermetically sealed state having a volume sufficient to convert dynamic pressure to static pressure between an engine unit disposed behind a front wheel and a fuel tank disposed above the engine unit. Is arranged, the intake port of the engine is located in the box, the rear end opening of the outside air introduction duct is connected, and the outside air introduction duct is gradually reduced in diameter from the rear end opening to the front end opening. The taper angle is set within 10 degrees.

Here, the box according to the present invention is not limited to the case where the box itself is formed in a substantially sealed shape, but also the case where the box is formed in a substantially sealed shape using a fuel tank as a part of the box. Including. In addition, the substantially sealed shape means that, for example, when a part of the fuel tank is used as a component surface of a box, a case where a seal between the two is not perfect and air flows in and out slightly is included. .

According to a second aspect of the present invention, in the first aspect, the inside of the box is defined by an introduction area into which outside air is introduced and a suction area by which air in the box is sucked into the engine, and can be communicated with each other. The introduction area has an introduction chamber located on the side of the cylinder block and having a smaller dimension in the vehicle width direction than other portions, and a rear end opening of the outside air introduction duct is directed toward the introduction chamber in the vehicle width direction. It is characterized by being connected.

A third aspect of the present invention is characterized in that, in the first or second aspect, the front end opening of the outside air introduction duct is arranged on the side opposite to the side where the disk plate and the caliper of the front wheel are arranged.

[0009]

According to the first aspect of the present invention, a substantially closed box having a sufficient capacity for converting dynamic pressure to static pressure is arranged, and the outside air introduction duct is connected to the box.
The outside air introduced through the outside air introduction duct has its flow velocity reduced to a negligible level in the box, and the dynamic pressure is reliably converted to static pressure. As a result, there is an effect that the intake air amount can be stably increased without being affected by the dynamic pressure.

Further, since the outside air introduction duct is formed in a tapered shape having a gradually decreasing diameter from the rear end opening to the front end opening, and the taper angle is set to 10 ° or less, the intake resistance of the outside air introduction duct is minimized. The intake amount can be increased from this point as well.

According to the second aspect of the present invention, the inside of the box is defined by an introduction area into which outside air is introduced and a suction area by which the air in the box is sucked into the engine. Is located on the side of the vehicle, the introduction chamber having a smaller dimension in the vehicle width direction than other parts is provided, and the rear end opening of the outside air introduction duct is connected to the introduction chamber in the vehicle width direction. It collides with the inner wall of the introduction chamber, whereby the flow velocity can be reliably reduced, the dynamic pressure can be more reliably converted to static pressure, and the influence of the dynamic pressure can be eliminated to stably increase the intake air amount. effective.

According to the third aspect of the present invention, the opening of the front end of the outside air introduction duct is located on the side opposite to the disk plate and the caliper of the front wheel, so that the fluctuation of the intake air amount due to the disturbance of the running wind due to the caliper is avoided. Further, there is an effect that it is possible to avoid a problem that dust generated from the brake pad is sucked into the engine through the outside air introduction duct.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 are views for explaining a motorcycle intake device according to an embodiment of the present invention. FIG. 1 is a left side view of a motorcycle provided with the intake device, and FIG. FIG. 3 is a perspective view of the box, FIG. 4 is a plan view of the box, and FIG. 5 is a characteristic diagram showing the relationship between the taper angle of the introduction duct and the intake resistance.
In addition, front and rear, left and right in the present embodiment means a case where the vehicle is viewed in a riding state.

In FIG. 1, reference numeral 1 denotes an intake device 2 of the present embodiment.
The motorcycle 1 includes a front fork 4 that supports a front wheel 3 at a lower end thereof by a head pipe 2a at a front end of a body frame 2 so as to be steerable left and right. Rear arms 6 that support the rear wheel 5 at the rear end are pivotally supported by the fork brackets 2c and 2c formed at the rear ends of the main frames 2b and 2b and the down tube 2d. It has a schematic structure in which an engine unit 7 is suspended and supported, a fuel tank 8 is mounted so as to straddle the main frames 2b, 2b, and a seat 9 is mounted behind the fuel tank 8. Reference numeral 10 denotes a cowling surrounding the engine unit 7 from above the front wheel 3 and from the front of the steering handle 4a, surrounding the engine unit 7, reference numeral 11 denotes a side cover surrounding the left and lower right sides of the seat 9 from behind, and reference numeral 18 denotes a side cover. It is a cushion unit of a rear wheel suspension device.

On the right side of the front wheel 3, a disc plate 19 constituting a disc brake device and a hydraulic caliper 20 for holding the disc plate 19 by a pad during braking are arranged. The disk plate 19
Is attached to the wheel hub of the front wheel 3, and the caliper 20
Are arranged so as to clamp the rear and upper peripheral edge of the disk plate 19, and are attached to the lower part of the front fork 4.

The engine unit 7 is a water-cooled two-cycle single-cylinder engine. A cylinder body 13 and a cylinder head 14 are laminated on a front upper surface of a crankcase 12 having a built-in transmission and fastened to the crankcase with bolts. The piston has a schematic structure in which a piston slidably inserted into a cylinder bore of the cylinder body 13 is connected to a crankshaft via a connecting rod. An exhaust pipe 16 of an exhaust device 15 is connected to an exhaust port formed to open to the front wall of the cylinder body 13. The exhaust pipe 16 is disposed so as to extend rearward through the lower side of the crankcase 12, and a silencer 17 is provided at a rear end of the exhaust pipe 16.
The silencer 17 is arranged on the right side of the rear wheel 5.

A radiator 26 is disposed in front of the cylinder body 13 and the cylinder head 14 so as to cross in the vehicle width direction and slightly tilt forward. The radiator 26 is connected via a return hose 26a to a cooling water pump 26b disposed on the left side wall of the crankcase 12, and a discharge port of the cooling water pump 26b is connected to the cylinder body 13 by a water supply hose 26c. Connected to cooling jacket.

At the corner between the upper wall of the crankcase 12 and the rear wall of the cylinder body 13, there is formed an intake port 13a communicating with the crank chamber in which the crankshaft is arranged. The carburetor 22 of the intake device 21 is connected to the intake port 13a via a joint 23. The carburetor 22 is located in a box 24 which is a feature of the present embodiment, and therefore, a suction port 22 a of the carburetor 22 is open in the box 24.

A fuel cock 28 attached to the bottom of the fuel tank 8 is connected to a fuel supply port 22c communicating with the float chamber of the vaporizer 22 via a fuel supply hose 22d. The pressure in the box 24 is introduced into the float chamber by a pressure introduction hose 22b.
Furthermore, the pressure in the box 24 is the hose 27c,
Tank 27b and hose 27a for storing blown fuel
Through the fuel tank 8. Thus, even when the pressure in the box 24 is higher than the atmospheric pressure, the fuel is supplied from the fuel tank 8 to the float chamber of the carburetor 22 without any trouble.

The box 24 is disposed in a space surrounded by an upper portion of the engine unit 7, a bottom portion of the fuel tank 8, and inner surfaces of the left and right main frames 2b, 2b. The box 24 is a resin molded product having a substantially bathtub-like appearance. Sealing flange portions 24a and 24a 'are formed by bending outward at the periphery of the upper end opening. On the upper surfaces of the flange portions 24a and 24a ', a seal step 8a and a bottom surface 8a' are formed so as to overhang the lower outer peripheral surface of the fuel tank 8.
Are in contact with each other with the sealing members 25, 25 'interposed therebetween.
Is substantially airtight, so that the box 24 is substantially hermetically sealed and has sufficient volume and passage cross-section to convert dynamic pressure to static pressure.

The box 24 is formed by a partition wall 24b disposed substantially at the center in the front-rear direction so as to extend in the vehicle width direction.
4d and the two regions 24c, 24d
Communicate with each other by the upper space a of the partition wall 24b.
Here, the upper portion of the bottom portion 24e of the introduction region 24d above the cylinder body 13 and the cylinder head 14 is formed so as to escape upward to avoid interference therewith.
On the other hand, a portion of the bottom portion 24e leftward from the cylinder body 13 and the cylinder head 14 is swelled downward so as to hang downward.
4f is formed.

An introduction hole 24i is formed in the outside wall 24g of the introduction chamber 24f so as to face the inside wall 24h. A rear end opening 25a of the outside air introduction duct 25 communicates with the introduction hole 24i. I have. The outside air introduction duct 25
Is a flange 2 formed around the rear end opening 25a.
5e is fixed to the box 24 by bolting and fastening to the outer wall 24g.

The outside air introduction duct 25 is an FRP molded product, has a circular cross section over its entire length,
g, slightly bent outward in the vehicle width direction, and then gently bent toward the front of the vehicle, and a bent pipe portion 25b therefrom, below the left end of the radiator 26 and the return hose 26
a, and has an introduction portion 25c extending forward through the outside of the front end portion 25a.
Protrudes forward from the cowling 10 and is located on the left side of the front wheel 3, that is, on the side opposite to the side where the disc plate 19 and the caliper 20 of the brake device are arranged.

The outside air introduction duct 25 has a tapered shape in which the rear end opening 25a has a maximum diameter and the front end opening 25d has a minimum diameter, and the diameter gradually decreases from the rear end opening 25a to the front end opening 25d. The taper angle α is set to 10 ° or less, more preferably 5 to 7 °. In addition, you may provide the straight pipe | tube part whose diameter does not change in the said front-end opening 25d part.

The reason why the taper angle α is set to 10 ° or less is to minimize the intake resistance. In other words, as shown in FIG. 5, the intake resistance of the outside air introduction duct has a taper angle α.
Is less than 10 °, that is, 0 °, that is, smaller than the case of a straight pipe, minimum when it is 5 to 7 °, and becomes larger than that of a straight pipe when it exceeds 10 °.

The outside air introduction duct 25 is formed such that the inner surface thereof is a gel coat surface or a surface to which a mold is attached in FRP molding, whereby the inner surface of the duct is smoothed to reduce the pipe resistance as much as possible. doing.

Further, in the curved pipe portion 25b of the outside air introduction duct 25, the inner surface R on the side with the smaller curvature (center side) is provided.
a is a dimple surface (rough surface) from the inner surface Rb on the larger side (outer side), whereby the inner surface Ra of the air flow is formed.
The separation from the tube is prevented, and the tube resistance is reduced.

Next, the operation and effect of this embodiment will be described. In the intake device 21 of the present embodiment, the outside air flows from the front end opening 25d through the outside air introduction duct 2 with the traveling of the motorcycle 1.
5 and is bent in the vehicle width direction by the bending pipe portion 25b, and enters the box 24 while colliding with the inner wall 24h of the introduction chamber 24f. Then, the air in the box 24 passes through the suction port 22a of the carburetor 22, becomes a mixture with fuel, and is sucked into the crank chamber of the engine unit 7, where it is primarily compressed and pushed into the cylinder bore during the scavenging stroke. After the compression stroke, combustion takes place.

In the above-described intake device 21, the motorcycle 1
As the traveling speed of the vehicle increases, the pressure in the box 24 increases, the amount of air-fuel mixture sucked into the engine increases, and the engine output increases. In this case, the box 24 of the present embodiment
Has a volume sufficient to reliably convert the dynamic pressure due to the air flow rate to a static pressure, that is, a volume capable of reducing the air flow rate in the box 24 to a negligible speed and a cross section perpendicular to the flow direction. Box 2 above
4 is defined by a partition 24b as an introduction region 24 into which outside air is introduced.
d and the suction area 24 where the suction port 22a of the vaporizer 22 is located.
c, the dynamic pressure can be reliably converted to the static pressure, the influence of the dynamic pressure can be eliminated, and the intake air amount can be stably increased.

Further, an introduction chamber 24f having a small size in the vehicle width direction is provided on the right side of the cylinder body 13 and the cylinder head 14 of the box 24, and the lower end opening of the outside air introduction duct 25 is opposed to the inner wall 24h. Flow collides with the inner wall 24h, whereby the flow velocity can be surely reduced, the dynamic pressure can be more reliably converted to static pressure, and the influence of the dynamic pressure can be eliminated to stably reduce the intake air amount. Can increase.

The taper angle α of the outside air introduction duct 25
Is set to 10 ° or less, and more desirably 5 to 7 °, the intake resistance of the outside air introduction duct 25 can be minimized, and from this point, the intake amount can be increased. In addition, the inner surface of the outside air introduction duct 25 is formed as a gel coat surface in FRP molding to reduce the intake resistance, and the inner surface Ra of the bend pipe 25b on the side of the center of the bend is roughened to prevent flow separation and to reduce bending loss. Therefore, the amount of intake air can be increased.

The front end opening 2 of the outside air introduction duct 25
Since 5d is located on the opposite side of the front wheel 3 from the disc plate 19 and the caliper 20, it is possible to avoid the fluctuation of the intake air amount due to the turbulence of the traveling wind. That is, when the front end opening 25d is arranged on the same side as the caliper 20, the traveling wind to the outside air introduction duct is disturbed by the caliper 20, but in this embodiment, the front end opening 25d is located on the opposite side of the caliper 20. Such arrangement does not cause such a problem.

When the front end opening 25d is arranged on the caliper 20 side, there is a concern that dust generated from the brake pad may be sucked into the engine through the outside air introduction duct, but in the present embodiment, the front end opening 25d is closed. Such a problem does not occur because it is arranged on the opposite side of the caliper 20.

Although the above embodiment has been described with reference to an engine having a carburetor, the present invention is of course applicable to an engine having a fuel injection valve.

[Brief description of the drawings]

FIG. 1 is a left side view of a motorcycle including an intake device according to an embodiment of the present invention.

FIG. 2 is a partially sectional left side view of the apparatus according to the embodiment.

FIG. 3 is a perspective view of a box of the apparatus according to the embodiment.

FIG. 4 is a plan view of a box of the apparatus according to the embodiment.

FIG. 5 is a characteristic diagram showing an experimental result of a relationship between a taper angle of an outside air introduction duct and an intake resistance of the embodiment device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motorcycle 3 Front wheel 7 Engine unit 8 Fuel tank 13 Cylinder block 19 Disk plate 20 Caliper 22a Suction port (engine intake port) 24 Box 24b Partition wall 24c Suction area 24d Introducing area 24f Introducing chamber 25 Outside air introduction duct 25a Rear end opening 25d Front end opening α Taper angle

Claims (3)

[Claims] 1. An intake system for a motorcycle in which a front end opening of an outside air introduction duct for introducing outside air is positioned ahead of an engine and a rear end opening of the outside air introduction duct communicates with an intake port of the engine. A substantially closed box having a volume sufficient to convert dynamic pressure to static pressure is disposed between the disposed engine unit and a fuel tank disposed above the engine unit, and the engine is disposed in the box. And the rear end opening of the outside air introduction duct is connected to the outside air introduction duct, and the outside air introduction duct is formed in a tapered shape that gradually becomes smaller in diameter from the rear end opening to the front end opening. An intake device for a motorcycle, wherein the intake device is set at 10 ° or less. 2. The air conditioner according to claim 1, wherein the inside of the box is defined as an introduction area into which outside air is introduced, and a suction area into which air in the box is sucked into an engine, and is communicable with each other. And an introduction chamber located on the side of the cylinder block and having a smaller dimension in the vehicle width direction than other portions, and a rear end opening of the outside air introduction duct is connected to the introduction chamber in the vehicle width direction. A suction device for a motorcycle, characterized in that: 3. The intake device for a motorcycle according to claim 1, wherein a front end opening of the outside air introduction duct is arranged on a side opposite to a side where the disk plate and the caliper of the front wheel are arranged. .