JPH0729632B2 - Intake noise reduction device for motorcycle engine - Google Patents

Description

The present invention relates to an intake air noise reduction device for an engine of a motorcycle, and an intake noise reduction device for reducing the intake noise of an engine of a motorcycle is provided near an air cleaner. For the installation, the dead space under the seat can be effectively utilized, and the resonance chamber is configured by using the seat bottom plate and the air cleaner, which simplifies the molding and processing for configuring the intake noise reduction device. The cost can be reduced.

[Conventional technology]

Since the engine of the motorcycle is located near the driver,
It is required to reduce the intake noise. The engine of a motorcycle is small in size, has a high output, and rotates at a high speed, so that its intake sound is louder, and therefore it is required to effectively reduce the intake sound.

As a device for reducing intake noise, one that connects a resonance chamber to an air cleaner to reduce air vibration of intake air, and an interference pipe whose other end is closed is connected to the air cleaner, and air vibration of intake air is generated by a reflected wave of the interference pipe. There is one that alleviates this by interfering with (see Japanese Utility Model Laid-Open No. 58-6957). The former has a greater effect of reducing the intake pipe than the latter, and its mechanism is simple, but it requires a large space for providing a resonance chamber. On the other hand, the latter does not require a special space because it can use a part of the body frame pipe as an interference tube, but the intake sound that can interfere is limited to air vibration of a limited frequency. , The effect of reducing the intake pipe is inferior.

In the type that reduces the air vibration of the intake air by connecting the resonance chamber to the air cleaner equipped with the intake duct, there is almost no space for providing a single resonance chamber around the motorcycle engine. In addition, a resonance chamber will be provided separately from the engine. For this reason, one independent resonance box and a pipeline for connecting the resonance box and the air cleaner are added, so that the number of assembly steps for the parts around the engine is increased and the weight is increased.

[Problems to be Solved by the Invention]

The present invention is based on the former intake noise reduction device, and devises the arrangement of the air cleaner and the resonance chamber so as to omit the conduit that connects the resonance chamber and the air cleaner, and utilizes the air cleaner and the seat bottom plate to create the resonance chamber. It is an object to devise the structure of the seat bottom plate and the air cleaner so that they can be formed.

[Means taken to solve the problem]

Means taken for solving the above-mentioned problems are constituted by the following elements (a) to (d) on the premise of an intake noise reduction device for a motorcycle in which a resonance chamber is connected to an air cleaner having an intake duct. Is. (A) A partition plate is provided on the lower surface of the center where the seat bottom plate is recessed upward, and an elastic sealing material is attached to the lower end of the partition plate. (B) The upper wall of the air cleaner penetrates the upper wall. A communication pipe that projects is provided, and an air intake duct that takes in outside air is provided on the side wall of the air cleaner. (C) The seat bottom plate is supported on the upper body frame via a cushioning material, and the air cleaner is arranged below the seat. A resonance chamber was constructed by pressing the elastic seal material at the lower end of the partition plate protruding downward from the seat bottom plate against the upper wall of the air cleaner, and (d) the front wall of the air cleaner and the carburetor were connected via a joint cleaner. thing.

[Action]

The seat bottom plate, the partition plate protruding downward from the seat bottom plate, and the upper wall of the air cleaner form a resonance chamber. Then, the lower end of the partition plate and the upper wall of the air cleaner abut on each other via the elastic sheet material attached to the lower end of the partition plate, and the abutting surface is sealed by the elastic sheet material. It is not necessary to fix the wall to each other, and the resonance chamber is formed by simply attaching the seat to the vehicle body frame and attaching the air cleaner at a predetermined position. Therefore, no special assembly procedure is required to assemble the resonance chamber by the lower end of the partition plate and the upper wall of the air cleaner.

Also, a special addition for forming the resonance chamber is a partition plate protruding downward from the seat bottom plate, an elastic sealing material attached to the lower end of the partition plate, and an interposing between the seat bottom plate and the upper body frame. Since the seat bottom plate is generally a cushioning material, and the seat bottom plate is generally a plastic molded product, the partition plate is integrally formed at the time of molding the seat bottom plate. Therefore, no special processing is required to provide this, and the weight is extremely small.

Further, since the lower end of the partition plate and the upper wall of the air cleaner are in contact with each other through the elastic sealing material and are not fixed to each other, the assembly positions of the both in the front-rear direction and the left-right direction of the vehicle body. Is not a problem at all, and the vertical displacement of the assembly position is due to the cushioning material interposed between the seat bottom plate and the upper body frame, and the elastic seal material attached to the lower end of the partition plate. Since it is compensated by the elastic deformation, the predetermined resonance chamber is hermetically sealed regardless of the vertical error of the mounting position of the seat bottom plate and the vertical error of the mounting position of the air cleaner. Further, a communication pipe penetrating the upper wall of the air cleaner is provided so as to project, and the resonance chamber and the air cleaner are communicated by this communication pipe. Therefore, a special pipe for communicating the resonance chamber and the air cleaner is used. No communication lines are required and no assembly work is required to connect these communication lines.

In addition, the frequency of the intake sound that is silenced by this resonance chamber (Where c is the speed of sound, V is the volume of the resonance chamber, l is the length of the communication pipe, and S is the cross-sectional area of the communication pipe), the frequency characteristic of the intake noise is examined and the frequency to be silenced is determined. Then, it is possible to cope with a frequency f in a considerably wide range by adjusting the length 1 of the communication tube and the cross-sectional area S of the communication tube without changing the volume of the resonance chamber. Further, since the central portion of the seat bottom plate is recessed upward, the volume V of the resonance chamber can be increased as much as possible. Therefore, the dead space between the seat bottom plate and the upper wall of the air cleaner can be used as effectively as possible to secure a resonance chamber having a volume V as large as possible between the seat bottom plate and the air cleaner, and further communication can be achieved. By adjusting the length of the pipe and the cross-sectional area of the communicating pipe, it is possible to absorb and relax the frequency f in a wide range.

Further, since the communication pipe that connects the resonance chamber and the air cleaner is provided on the upper wall of the air cleaner, while the intake duct that takes in outside air is provided on the side wall of the air cleaner, the communication pipe and the intake duct are provided on the air cleaner. The decrease in the physical strength of the casing (the decrease in the physical strength of the casing of the air cleaner due to the vibration of the communication pipe and the intake duct) can be reduced as much as possible. Therefore, the plate thickness of the casing of the air cleaner can be limited to the limit required to secure the strength of the casing of the air cleaner, and the plate thickness of the casing of the conventional air cleaner can be adopted as it is.

As described above, the lower surface of the seat bottom plate is recessed upward, the partition plate is projected on the lower surface, the elastic sealing material is attached to the lower end of the partition plate, and the elastic material is attached to the bearing surface of the seat bottom plate by the body frame. There is no need to add any special members other than the interposition of the above, no structural modification, no special molding or processing, and the resonance chamber can be created by attaching the seat bottom plate to the vehicle body frame and attaching the air cleaner to a predetermined position. Further, the resonance chamber and the air cleaner are communicated with each other via a communication pipe provided on the upper wall of the air cleaner. Therefore, the addition of parts, the increase in weight, the increase in molding, and the increase in processing can be reduced as much as possible, and a special conduit for connecting the resonance chamber and the air cleaner can be omitted. , It is possible to easily and easily configure the intake noise reduction device having the required characteristics by making the most effective use of the dead space under the seat.

Even if the partition plate for forming the resonance chamber is provided so as to project upward from the upper surface of the upper wall of the air cleaner, the desired function is achieved. In this way, when the partition plate is projected upward from the upper surface of the upper wall of the air cleaner, there is a disadvantage that the structure of the conventional air cleaner is changed, but the upper wall is reinforced by the partition plate and the rigidity of the air cleaner is improved. There is an advantage of doing. In this case, an elastic sealing material is attached to the upper end of the partition plate, and this is brought into pressure contact with the lower surface of the seat bottom plate which is recessed upward.

Whether the partition plate is projected downward from the seat bottom plate or upwardly projected from the upper wall of the air cleaner can be appropriately selected in consideration of the above advantages and disadvantages, and they are technically equivalent means. .

〔Example〕

 Next, embodiments will be described with reference to the drawings.

The motorcycle shown in FIG. 1 is an off-road motorcycle having a diamond-shaped body frame, and is an example to which the present invention is applied.

In this embodiment, the air cleaner 3 is provided behind the engine 1 in an inverted triangular space surrounded by a pair of upper frame 2a, central frame 2b and lower frame 2c.
Are arranged and fixed to the rear frame 2c with bolts or the like.

The front wall of the air cleaner 3 is connected to the front carburetor 5 by a joint air cleaner 4.
Cover 3b detachably attached to the air cleaner body
The element can be taken out by removing, and an intake duct 3c for taking in outside air is provided on the side surface of the air cleaner body. The seat 6 is placed on the upper frame 2a above the air cleaner 3, and the front and rear ends of the bottom plate 6a are detachably fixed to the frame. The central portion of the seat 6 is supported by being partially in contact with the left and right upper frames 2a via a cushioning material (rubber) 12 (second).
See figure). As a result, a space is formed between the upper surface of the upper wall 3a of the air cleaner 3 arranged below the seat 6 and the bottom plate 6a of the seat 6.

A central portion of the seat bottom plate 6a is recessed upward, and a box-shaped partition plate 7 projects downward from the seat bottom plate 6a. Then, a continuous rectangular elastic seal material 8 made of sponge or the like is attached to the tip of the partition plate 7, and the elastic seal material 8 is placed on the upper frame 2a while the elastic seal material 8 is on the upper wall of the air cleaner 3. It is pressed against 3a. As a result, a sealed resonance chamber 9 surrounded by the upper wall 3a, the partition plate 7 and the seat bottom plate 6a is formed above the air cleaner 3. Then, a through hole is formed substantially in the center of the upper wall 3a of the air cleaner 3, and a communication pipe 10 is fixedly provided in this through hole, whereby the internal space of the air cleaner 3 and the resonance chamber 9 are communicated with each other.

The volume of the sounding chamber 9 is V, the length of the communicating pipe 10 is 1, and the communicating pipe
If the cross-sectional area of 10 is S, the frequency f silenced by the resonance chamber 9 is (Where c is the speed of sound), the frequency of the intake sound is examined and the frequency to be silenced is determined. Based on the above equation, assuming the appropriate volume V of the resonance chamber, By adjusting the height l and the cross-sectional area S, it is possible to reduce the intake noise at a predetermined frequency.

As a result, even if the resonance chamber 9 is provided and the intake sound is to be suppressed after the basic design of the vehicle body is completed,
The resonance chamber can be easily formed by effectively utilizing the dead space under the seat without changing the layout of the vehicle body or changing the mechanical design of the air cleaner 3.

Further, although the seat 6 is attached to the upper body frame 2a with a relatively rough accuracy, the elastic seal member 8 is attached to the tip of the partition plate 7 to bring it into contact with the upper wall 3a of the air cleaner as described above. Therefore, the vertical error of the seat mounting position and the vertical error of the mounting position of the air cleaner 3 can be compensated by the elastic deformation of the cushioning material 12 and the elastic sealing material 8 to secure the airtightness of the resonance chamber 9. .

In the above embodiment, the elastic sealing material 8 at the tip of the partition plate 7 is used.
The upper wall 3a of the air cleaner 3 which is pressed against is not necessarily flat as shown in the drawing, but may be curved. In that case, the same curve as the upper wall 3a of the air cleaner may be attached to the tip of the partition plate 7.

Further, in the above embodiment, the partition plate 7 is integrally formed with the seat bottom plate 6a in consideration of the convenience of mounting the air cleaner 3 on the vehicle body, but the convenience of mounting the air cleaner 3 on the vehicle body must be taken into consideration. If the partition plate 7 is placed on the upper wall 3a of the air cleaner 3,
However, in this case, the structure of the air cleaner needs to be changed (the air cleaner used in motorcycles without an intake noise reduction device can be used). No, so it is necessary to consider this point. Depending on the layout of the vehicle body, there are many cases where a sufficiently large space does not exist between the bottom plate 6a of the seat 6 and the upper wall 3a of the air cleaner, but even in this case, the lower surface of the seat 6 is positively recessed upward. The necessary volume of the resonance chamber can be secured by providing a partition plate around it.

Further, since the communication pipe 10 that communicates with the inside of the resonance chamber 9 is integrally formed on the upper wall 3a of the air cleaner, the air cleaner and the inside of the resonance chamber 9 are connected by the communication pipe 10 only by assembling the seat and the air cleaner to the vehicle body frame. Since they are communicated with each other, it is not necessary to provide another communication pipe for communicating the air cleaner and the resonance chamber 9 outside the resonance chamber and the air cleaner, or to assemble the communication pipe.

〔The invention's effect〕

It is not publicly known that the resonance chamber is configured by using the seat bottom plate and the upper wall of the air cleaner. Therefore, the said subject of this invention is novel, and it is the largest peculiar effect of this invention that this novel subject was solved and the said problem was solved.

In addition, the addition of parts, molding,
The fact that many effects such as the addition of processing steps and the increase of assembly labor can be reduced as much as possible to reduce the cost as much as possible and the weight increase can be reduced as much as possible ] As described above.

Furthermore, the central part of the seat bottom plate is recessed upward, and a partition plate is projected downwardly around it to form a resonance chamber surrounded by the partition plate under the seat, and this resonance chamber communicates with the inside of the air cleaner body. By adopting this mechanism, even after the basic design of the vehicle body is completed, the dead space under the seat is utilized to the maximum extent, and the resonance chamber with the largest possible volume is constructed in the narrow dead space under the seat. By the action that can be done, it is possible to reduce the intake sound without changing the layout of the vehicle body or the basic structure of the air cleaner.
It is also a great advantage of the present invention that the maximum intake sound frequency of the intake sound reducing device can be easily and easily adjusted by adjusting the length of the communication pipe and the cross-sectional area of the communication pipe.

[Brief description of drawings]

FIG. 1 is a side view of the entire motorcycle showing an embodiment, and FIG. 2 is a sectional view taken along the line AA in FIG. 1 ... Engine, 2a-2c ... Body frame, 3 ... Air cleaner, 3a ... Upper wall, 3b ... Cover, 3c ... Intake duct, 4 ... Joint air cleaner, 5 ... Carburetor, 6 ... Seat, 6a
... Seat bottom plate, 7 ... Partition plate, 8 ... Elastic seal material, 9 ... Resonance chamber, 10 ... Communication pipe, 12 ... Buffer material (rubber).

Claims (1)

[Claims] 1. An intake air noise reducing device for a motorcycle engine, wherein a resonance chamber is connected to an air cleaner having an intake duct, wherein a partition plate is provided on a lower surface of a center where a seat bottom plate is recessed upward, and the partition plate is projected downward. An elastic sealing material is attached to the lower end of the plate, a communication pipe penetrating the upper wall of the air cleaner is projected, and an intake duct for taking in outside air is provided on the side wall of the air cleaner. The air cleaner is supported on the body frame, the air cleaner is arranged below the seat, and the elastic seal material at the lower end of the partition plate protruding downward from the seat bottom plate is pressed against the upper wall of the air cleaner to form the resonance chamber. The intake noise reduction device described above in which the wall and the carburetor are connected via a joint cleaner.