JPH0774018B2 - Intake silencer for motorcycles - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an intake silencer provided in a motorcycle.

[Prior Art] As a vehicle body frame of a motorcycle, a so-called delta box shape is formed in which the main frame has a hollow rectangular cross section, the front end side in the longitudinal direction is wide, and the width becomes narrower toward the rear. The one in which a pair of main frames is provided on the left and right has been receiving attention.

On the other hand, it has been known that the larger the volume of the intake muffler provided in the motorcycle, the higher the muffling performance.
However, in a motorcycle, the installation space for accessories is smaller than that in a four-wheeled vehicle, so there is a problem that the vehicle body must be enlarged to increase the volume of the intake silencer, as described above. This will increase the weight and increase the cost.

[Object of the Invention]

It is an object of the present invention to provide an intake silencer for a motorcycle, which utilizes the above-mentioned delta-box type main frame and can exhibit a high silencing effect without narrowing the installation space for other devices. It is in.

[Structure of Invention]

According to the present invention to achieve the above object, a main frame having a hollow rectangular cross section and a front end in the longitudinal direction formed to have a width substantially equal to the length of a steering shaft tube has a saddle shape in a plan view at the rear portion of the steering shaft tube. As described above, the engine is connected in a bifurcated right and left direction, tilted forward so that the extension of the axis of the cylinder intersects with the steering shaft tube, and has an intake system component on the back of the cylinder and an exhaust system component on the front. In the mounted motorcycle, the hollow portion is communicated with the outside air through an intake hole having an opening smaller than the maximum cross-sectional area of the hollow portion in the main frame that is saddle-shaped in plan view at the rear portion of the steering shaft tube. A retainer having a filter element installed therein is mounted on the back surface of the main body, and the filter element is arranged so as to be inclined with respect to a vertical plane with respect to the vehicle front-rear direction. Left and right 2 apart from the axial tube rearward A ventilation hole communicating with the filtration element is provided at the position, the intake passage is turned up and down at the outlet of the retainer, and the intake passage is extended substantially vertically through the carburetor in the middle. It is characterized by being connected to the intake system of the engine.

〔Example〕

In the motorcycle shown in FIG. 3, 1 is a steering shaft tube, 2 is a main frame, 3 is a back stay, and 4 is a down tube connecting between a lower front end of the main frame 2 and a lower part of the back stay 3. Reference numeral 5 denotes an engine mounted on a vehicle body frame formed of these members. Engine 5
The cylinder is greatly tilted forward, and the axis of the cylinder extends A-A '
Intersects with the steering shaft tube 1, and the intake system of the engine 5 communicates with an intake passage that extends in a substantially straight line in the vertical direction, and a down-draft type vaporization is provided in the middle of the intake passage. The exhaust pipe is attached to the exhaust system.
15 is attached. These intake system parts are arranged on the back side of the cylinder, and the exhaust system parts are arranged on the front side.

As shown in FIG. 1 and FIG. 2, a pair of left and right main frames 2 and 2 are provided, the front ends of which are welded to the rear part of the steering shaft tube 1 and extend obliquely outward, and further curved and extend rearward. There is. The main frame 2 has a half-divided outer plate 2a and inner plate 2b.
And are welded to form a hollow rectangular cross section, and the front end in the longitudinal direction is as wide as the length of the steering shaft tube 1 and becomes narrower toward the rear. It is formed and has a so-called delta box shape. The front end portions of the left and right inner plate portions 2b, 2b are integrally connected to form a saddle shape, and a delta-shaped space 6d is formed therein.

On the outer wall forming the inner plate portion 2, a large number of intake holes 8, ..., 8 are provided in the inner surface portion so as to penetrate into the hollow portion 6, and further on the front side of the steering shaft tube 1. A plurality of vent holes 9, ... 9 communicating with a filter element 10 to be described later are provided in the two hollow portions in the left and right of the main frame 2,2 having a saddle shape in plan view at the rear portion so as to penetrate the outer wall. A filter element 10 that is inclined with respect to a vertical plane with respect to the vehicle front-rear direction is attached to and attached to a retainer 11 outside the group of vent holes 9. An air supply pipe 12 is provided on the outlet side of the retainer 11, and the air supply pipe 12 turns from a substantially horizontal direction to a vertical direction and goes downward to the engine 5 through a substantially straight down-draft type carburetor 7. is doing.

Also, in the portion near the front end in the hollow portion 6, holes 14, ..., 14
A baffle plate 13 is provided. The baffle plate 13 has a function of reflecting and attenuating the intake sound, and also functions as a reinforcing plate.

When the engine 4 is driven in the motorcycle described above,
Outside air is sucked into the hollow portion 6 from the intake holes 8, ..., 8 of the main frame 2, and the hollow portion 6 is used as an intake passage for the ventilation holes 9 ,.
After passing through ..9, the filter element 10 removes dust, and then reaches the carburetor 7, where it is mixed with fuel and supplied to the engine 4. As described above, when the outside air is sucked into the hollow portion 6 from the intake hole 8, an intake sound is generated, but the intake sound is silenced because it is attenuated while repelling the inner wall of the main frame 2.

That is, since the front ends of the main frames 2, 2 are as wide as the length of the steering shaft tube 1, the hollow portion 6 having a large volume is configured as an intake silencer. Therefore, unlike the conventional case, the space for installing the intake silencer in the area surrounded by the vehicle body frame is not required, and the space for other accessory devices is not narrowed. Moreover, since the hollow portion 6 of the main frame 2 is long in the longitudinal direction and has a large volume, and has a large cross-sectional area on the front end side and is gradually reduced toward the rear, it is effective in damping a wide range of frequencies. Can be exhibited, and a high-performance silencing effect can be exhibited.

Further, if the baffle plate 13 is provided as in the above embodiment, the sound deadening effect can be further enhanced. In the present invention, the baffle plate 13 is not always necessary, but when it is provided, it is not limited to one as in the embodiment, but a plurality of baffle plates 13 may be provided at important points. Further, the installation position may be symmetrical or asymmetrical with respect to the center of the vehicle body passing through the steering shaft tube 1. Further, the number of holes 14 provided in the baffle plate 13 is also arbitrary, and when a plurality of holes 14 are provided, the sizes of the holes may be different from each other.

Further, since the intake hole 8 in the above-described embodiment is provided on the inner side surface of the outer wall of the main frame 2, it becomes difficult to visually recognize it from the outside, thereby improving the appearance. Further, it is possible to reduce the inhalation of water and dust and to make it advantageous for separation. From this point of view, the intake hole 8 may be provided on the lower surface of the main frame 2.

Further, since the intake passage extending from the retainer 11 of the filter element 10 to the engine 5 is tilted forward and the intake passage parts are arranged on the rear surface of the cylinder, the intake passage extends almost vertically and is generally linear. And the filter element 10 is arranged so as to be inclined with respect to a vertical plane with respect to the vehicle longitudinal direction,
It becomes possible to secure a wide filtration area with respect to the flow in the front-back direction, and further, the intake hole to the filtration element 10 is provided at a position separated rearward from the steering shaft tube 1 in the hollow portion of the main frames 2,2. Since it is provided at two places on the left and right, intake resistance can be significantly reduced and the output of the engine 5 can be increased.

〔The invention's effect〕

As described above, according to the present invention, a main frame having a hollow rectangular cross-section and a front end in the longitudinal direction formed to have a width substantially equal to the length of the steering shaft tube has a saddle shape in plan view at the rear portion of the steering shaft tube. The engine is connected in a bifurcated manner to the left and right, is tilted forward so that the extension of the cylinder axis intersects with the steering shaft tube, and is equipped with an intake system component on the back of the cylinder and an exhaust system component on the front. In the above motorcycle, while communicating with the outside air through an intake hole having an opening smaller than the maximum cross-sectional area of the hollow portion in the main frame that is saddle-shaped in plan view at the rear portion of the steering shaft tube, the hollow portion of the hollow portion A cage with a filter element installed on the back is installed, and this filter element is arranged so as to be inclined with respect to a vertical plane with respect to the vehicle front-rear direction, and the hollow portion in the main frame that is saddle-shaped in plan view is steered. Two places on the left and right of the position separated from the shaft tube rearward A ventilation hole communicating with the filtration element is provided, and the intake passage is turned up and down at the outlet of the retainer, and the intake passage is extended substantially vertically through the carburetor in the middle of the intake passage of the engine. Since it is configured to communicate with the intake system, the hollow part in the main frame is used as an intake silencer, so no special space is required for installing the intake silencer, and the installation space for other auxiliary equipment is reduced. There is no such thing.

Moreover, since the hollow portion has a saddle shape in plan view at the rear portion of the steering shaft tube and the front end of the main frame is wide and has a large volume, a high silencing effect can be obtained.

In addition, the engine is mounted with a large forward inclination so that the extension line of the cylinder intersects with the steering shaft tube, and the intake passage from the holder of the filter element provided on the back surface of the hollow portion to the engine is almost vertical. Since it is linear, it is generally short, and since the filtering element is arranged inclined with respect to the vertical plane with respect to the vehicle front-rear direction, it is possible to secure a wide filtering area, and Left and right of the position where the intake holes to the filter element are separated from the steering shaft tube rearward.
Since it is installed in several places, it significantly reduces the intake resistance,
The output of the engine 5 can be increased.

[Brief description of drawings]

FIG. 1 shows a main frame constituting the intake silencer of the present invention,
Fig. 2 is a sectional view taken along the line I-I of Fig. 2, Fig. 2 is a sectional view showing the main frame taken along the line II-II of Fig. 1, and Fig. 3 is a side view of the motorcycle provided with the main frame. It is a figure. 2 ... Main frame, 5 ... Engine, 6 ... Hollow part, 7
...... Vaporizer, 8 ... Intake hole, 9 ... Vent hole, 10 ... Filtration element.

Claims (3)

[Claims] 1. A main frame having a hollow rectangular cross section and a front end in the longitudinal direction formed to have a width substantially equal to the length of the steering shaft tube. The main frame is bifurcated to the rear of the steering shaft tube in a saddle shape in plan view. Motorcycles that are connected in a line and are tilted forward so that the extension of the axis of the cylinder intersects with the steering shaft tube, and that has an intake system component on the back of the cylinder and an exhaust system component on the front. At the rear of the steering shaft tube, the air is communicated with the outside air through an intake hole having an opening smaller than the maximum cross-sectional area of the hollow portion in the main frame that is saddle-shaped in plan view, and the rear surface of the hollow portion is filtered. A retainer in which an element is installed is mounted, the filtering element is arranged so as to be inclined with respect to a vertical plane with respect to the vehicle front-rear direction, and a steering shaft tube in a hollow portion in the main frame having a saddle shape in plan view Left and right 2 apart from each other
A ventilation hole communicating with the filtration element is provided at a location, the intake passage is turned up and down at the outlet of the retainer, and the intake passage is extended substantially vertically in the middle through a carburetor. An intake silencer for a motorcycle, wherein the intake silencer is connected to the intake system of the engine. 2. The intake silencer for a motorcycle according to claim 1, wherein the intake hole is provided on the inner side surface of the outer wall of the main frame. 3. The intake silencer for a motorcycle according to claim 1, wherein the intake hole is provided on the lower side surface of the outer wall of the main frame.