JPH02296586A - Intake device for motorcycle - Google Patents

Abstract

PURPOSE:To obviate a space for arranging a fuel supply device and the like between an engine and a front wheel, and increase the degree of freedom in positioning the engine by providing the fuel supply device under a crankcase with the upstream side thereof directed back, and installing an air cleaner at the back of the fuel supply device. CONSTITUTION:Intake openings 11b are formed on the bottoms of right and left crank chamber 11a in the crankcase 11 of the engine unit 10 of a motor cycle 1, and intake tube parts 11c are integrated with each intake opening 11b in such a way as to be extended backward down at an angle of about 60 degrees from a horizontal plane. Furthermore, a delivery port 20 as the downstream side opening of a carburetor (fuel supply device) 20 is connected to each intake part 11c via a elbow-shaped carburetor joint 19. Also, a pair of right and left air cleaners 21 is arranged aft of the car buretor 20, and under a crankcase 11 and a rear arm bracket 2c, and each cleaner 21 is connected to the intake port 20a of the carburetor 20 via a connection joint 22.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intake device for supplying clean air filtered by an air cleaner to a two-stroke motorcycle engine, and particularly relates to a front intake/back exhaust system. The present invention relates to an improvement in the arrangement structure of a fuel supply device and an air cleaner that can prevent an increase in the distance between the axles (wheel heath) or increase the front wheel load when adopted.

[Conventional technology]

Some modern motorcycles have a so-called front intake, rear exhaust system in which the carburetor is connected to the front of the engine and the exhaust pipe is connected to the rear of the engine. This type of motorcycle was developed for competition use, in which it runs at high speed on a predetermined course, and the intake system of this competition motorcycle is equipped with an air cleaner to reduce intake resistance as much as possible and improve output. It is constructed so that outside air is directly sucked in without providing a filter (for example, see Japanese Patent Application No. 168815/1982).

[Problem that the invention seeks to solve]

By the way, in order to employ the above-mentioned front intake/rear exhaust system in a commercially available motorcycle for use on public roads, it is necessary to supply the engine with clean air filtered by an air cleaner in order to ensure the durability of the engine. In this case, it is necessary to develop an intake system appropriate for the special structure in which the fuel supply system is connected to the front side of the engine. For example, depending on the arrangement of the carburetor and air cleaner, the connection between the engine and the rear edge of the front wheel There are concerns that the wheelbase will become longer to ensure space for air cleaners and the like by widening the gap, or that the center of gravity will move back and the load on the front wheels will decrease.

Therefore, in view of the above-mentioned situation, the present invention provides a front air intake system for commercially available vehicles.
When adopting the rear exhaust system, there is no need to create a large gap between the engine and the rear edge of the front wheels, allowing greater freedom in the placement of the engine.As a result, the engine can be mounted closer to the front if necessary. , this allows the foil base to be shortened,
Another object of the present invention is to provide an intake system for a motorcycle that can increase the load on the front wheel when the wheel base is the same as before.

[Means for Solving the Problems] The present invention provides an intake system for a motorcycle in which an exhaust pipe is connected to the rear side of the engine, in which the fuel supply device is located below the bottom wall of the crankcase, and the intake port extends toward the rear of the vehicle. At the same time, the discharge port of the fuel supply device is connected to an intake opening formed at the bottom of the crank chamber, and the discharge port of the fuel supply device is connected to the intake port of the fuel supply device behind the fuel supply device and from the crankcase. It is characterized by connecting an air cleaner located below.

Here, the fuel supply device of the present invention includes both a normal carburetor and a fuel injection device in which a fuel injection valve and a throttle valve are arranged in a venturi pipe.

C Effect] According to the intake device according to the present invention, the intake opening is formed at the bottom of the crank chamber, the fuel supply device is arranged rearward and connected to the intake opening, and the fuel supply device is connected to the intake opening at the rear thereof. Since the installed air cleaner is connected, there is no need to secure a space between the engine and the rear edge of the front wheels for the air cleaner, fuel supply system, etc. Therefore, for example, if the fuel supply system is connected to the front wall of the cylinder body or crank chamber, The degree of freedom in terms of engine placement can be expanded compared to when the engine is connected to the engine. Therefore, if necessary, the wheelbase can be shortened by placing the engine closer to the front and moving the rear wheels closer to the front, or if the wheelbase remains the same, the front wheel load will be increased to improve handling stability. You can improve.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 are diagrams for explaining an intake system for a motorcycle according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a motorbike or motorcycle in which the device of this embodiment is adopted, and its body frame 2 has left, right (hereinafter referred to as front, rear, left A rear arm bracket 2c is integrally formed on the rear end portions of a pair of main frames 2b (all ``right'' refers to the case facing the front of the vehicle), and both brackets 20 are connected to each other by a cross vibe 2d. The front fork 4 pivotally supports the front end 3 at its lower end by the head vibe 2a.
is pivotally supported so that it can be steered left and right, and a left-right split type traveling handle 4a is fixed to the upper end of the core fork 4. Further, the rear arm 6, which pivotally supports the rear wheel 5 at its rear end, is pivotally supported by the rear arm bracket 2C so as to be able to swing up and down.

Further, a fuel tank 7 and a seat 8 are arranged in order from the front on the upper side of the vehicle body frame 2, and the left, right and rear sides of the seat 8 are covered with side covers 9a. Furthermore, the left, right, and lower sides of the vehicle body frame 2 are surrounded by a cowling 9, and an engine unit 10 is suspended and supported within the cowling 9. This engine unit 10 is a water-cooled two-stroke parallel two-cylinder type, and has a cylinder body 12. and the cylinder head 13 is mounted in a forward tilted state, and this is attached to the hend bolt 14.
It has a structure in which it is fastened to the crankcase 11.

A pair of left and right exhaust ports 12a, 12a are formed in the rear wall of the cylinder body 12, and a pair of left and right exhaust pipes 15, 15 are formed in the left and right exhaust ports 12a, 12a. The front end is connected. Each exhaust pipe 15 extends obliquely upward in a substantially straight line from the inside of the left and right main frames 2b to the rear end of the vehicle, passing through the inside of the side cover 9a.

Further, the left and right pistons 16 inserted into each cylinder of the cylinder body 12 are connected to the left and right crank arms 17a of a crankshaft 17 arranged in the front part of the crankcase 11 in the vehicle width direction. , are connected via a connecting rod 18, respectively.

Each crank arm 17a has left and right crank chambers 11a integrally formed within the crankcase 11.
Located within. Note that 12b is an exhaust timing control device.

In addition, intake openings 11b are formed at the bottoms of the left and right crank chambers 11a, respectively.
An intake pipe portion 11c is integrally formed on 1b so as to extend downward at an angle of about 60 degrees with respect to the horizontal plane. A discharge port 20b, which is a downstream opening of the carburetor 20, is connected to each intake pipe portion 11c via a cap 19. The cab joint 19 is made of hard rubber and has an elbow shape with both end faces having an angle of approximately 60 degrees. Therefore, the axis of the venturi passage 20c of each carburetor 20 is substantially horizontal and located below the bottom surface of the crankcase 11, and the intake port 20a, which is the upstream opening, faces toward the rear of the vehicle.

Also, behind the carburetor 20 and the crankcase 1
1 and the lower position of the rear arm bracket 2C are the left,
A right pair of air cleaners 21 are arranged with a buffer 30 in between. This air cleaner 21 is of a type divided into a front and a rear part, and is connected to the intake port 20a of the carburetor 20 via a connecting joint 22.

Further, in front of and above the cylinder head 13, a radiator 24 is arranged so as to span between the lower parts of the left and right main frames 2b. This radiator 2
4 is a core part 24 whose central part is curved convexly toward the rear of the vehicle in order to avoid interference with the front wheels 3 and to expand the airflow area, and a head tank part connected to the left and right sides of the core part 24. 24b, and although not shown, the left and right head tank portions 24b are connected to a circulation pump disposed in the crankcase 11 and the cylinder head 13 via cooling water hoses. In addition, the left and right head tank parts 24
The portion b is fixedly supported by support brackets 28 fixed to the left and right main frames 2b.

Next, the effects of this embodiment will be explained.

In the intake system of this embodiment, the air sucked into the air cleaner 21 is filtered by the element and then sucked into the carburetor 20, where it becomes a mixture with gasoline and is sucked and supplied into the crank chamber 11a. Ru.

Since the air cleaner 21 is disposed behind the carburetor 20 and the two are connected in this manner, clean air can be supplied to the engine without any hindrance while adopting the front intake/rear exhaust system.

On the other hand, as mentioned above, in order to adopt the front intake method,
For example, if a carburetor or air cleaner is placed between the front wheels and the engine, the engine must be moved to the rear to ensure space for these devices, which may lengthen the wheel base or reduce the load on the front wheels. There are concerns that this may lead to a decline in In contrast, in this embodiment, the carburetor 20 is arranged rearward under the crankcase 11, and the air cleaner 20 is arranged behind the carburetor 20.
1 is connected, there is no need to secure a space for arranging a carburetor or the like between the engine IO and the rear edge of the front wheel 3, thus increasing the degree of freedom in the arrangement position of the engine 10. As a result, when the engine 10 is mounted closer to the front and the rear end 5 is arranged closer to the front in accordance with the amount of the front, the wheel base can be shortened. Furthermore, if the wheelbase remains the same and only the engine is moved to the front, the front wheel load can be increased.

〔Effect of the invention〕

As described above, according to the intake system for a motorcycle according to the present invention, the fuel supply device is disposed below the crankcase with the upstream side facing backward, and the air cleaner is disposed behind the fuel supply device. This eliminates the need for a mounting base for a fuel supply system, etc. between the front wheel and the front wheels, which increases the degree of freedom in terms of engine placement, such as placing the engine closer to the front, and allows the wheelbase to be shortened if necessary. , or has the effect of increasing the front wheel load.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining an intake device for a motorcycle according to an embodiment of the present invention, and FIG. 1 is a left side view of a motorcycle in which the embodiment device is adopted, and FIG. The figure is a bottom view showing the arrangement of the carburetor and air cleaner in the vehicle width direction. In the figure, 1 is a motorcycle, 10 is an engine, 11 is a crankcase, lla is a crank chamber, 11b is an intake opening, 15 is an exhaust pipe, 19 is an exhaust pipe, 20 is a carburetor (
20a is an intake port, 20b is a discharge port, 2
1 is an air cleaner. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu No. 2

Claims (1)

[Claims] (1) In a motorcycle having an exhaust pipe connected to the rear side of a two-stroke engine, an intake device for supplying clean air to the engine, wherein the fuel supply device is installed below the bottom wall of the crankcase and the intake pipe is connected to the rear side of the engine. The fuel supply device is arranged so that its mouth faces toward the rear of the vehicle, the discharge port of the fuel supply device is connected to an intake opening formed in the crank chamber, and an air cleaner is provided behind the fuel supply device and below the bottom wall of the crankcase. An air intake system for a motorcycle, wherein the air cleaner is connected to an air intake port of the fuel supply system.