JPH06249092A - Variable resonance type silencer - Google Patents

Abstract

PURPOSE:To provide a variable resonance type silencer kept airtight and miniaturized by partitioning a communicating pipe of the variable resonance type silencer into a plurality of paths and disposing a movable members in a resonance chamber. CONSTITUTION:A communicating pipe 2 is adapted to communicate with a duct 1. The interior of the communicating pipe 2 is partitioned by a partition wall 3 to form a path 4. The communicating pipe 2 is adapted to communicate with a resonance chamber 5 in which a movable member 7 is disposed and connected to a gear body 8 and stepping motor 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable resonance silencer used for an intake duct of an internal combustion engine, for example.

[0002]

2. Description of the Related Art A resonance silencer is installed in the middle of an intake duct, and is composed of a communication pipe communicating with the inside of the duct and a resonance chamber having an opening at the end of the communication pipe. With respect to the generated noise, the damping effect is obtained only at a specific resonance frequency. For this reason, in recent years, a variable resonance silencer has been used to continuously change the resonance frequency according to the noise frequency and widen the frequency range that can be attenuated. The factors that change the frequency of this variable resonance silencer include the volume of the resonance chamber, the length of the communication pipe, and the opening area thereof. Normally, however, the resonance chamber volume can be changed without making it variable in order to obtain a large silencing effect. It should be as large as possible to change the communication pipe length or opening area. Among these, the one that changes the opening area of the communication pipe can obtain a relatively large frequency change with a small amount of change, but a wide range change in the resonance frequency is expected by simply changing the opening area of the pipe end of the communication pipe. This cannot be done, and the opening area of the communication pipe is changed over the entire length.

FIG. 5 shows a variable resonance type silencer for changing the opening area of the communication pipe over the entire length. The cylindrical duct 1 and the side wall of the fixed wall 22a and the movable wall 22b form a cylindrical communication. It is composed of a pipe 22 and a resonance chamber 15, and a movable wall 22 b of the communication pipe 22 is connected to an actuator 23. Then, the movable wall 22b of the communication pipe 22 is moved by the actuator 23 in accordance with the frequency, the opening area of the communication pipe 22 is changed, and the resonance frequency is tuned to attenuate the noise.

[0004]

By the way, in this conventional variable resonance silencer, a part of the movable wall, that is, the side wall of the communicating pipe in the circumferential direction is moved over its entire length. There is a technical difficulty in securing the airtightness of the fixed wall of the muffler to the movable wall, and the movable wall of the communication tube also becomes large, requiring a high-power actuator, and the mounting site must be solid, and the silencer It becomes heavy in itself.

[0005]

The present invention is a variable resonance silencer, in which a tubular communication pipe is communicated with a tubular duct, and the interior of the communication pipe is partitioned by partition walls to form a large number of passages in the axial direction. The communication pipe tube end is opened inside the box-shaped resonance chamber, and a plate-like movable member for closing the communication pipe tube end is movably arranged in the resonance chamber, and the drive member is connected to the movable member.

[0006]

With respect to the noise frequency, the drive means receives a signal synchronized with the engine rotation and slides the movable member by an amount corresponding to the signal. At this time, the communication pipe covers only the required number of passages, the duct and the resonance chamber communicate with each other through the communication pipe set to have a required opening area, and the variable resonance silencer tunes to the resonance frequency.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the variable resonance silencer of the present invention will be described with reference to FIGS. The intake duct 1 is made of synthetic resin and has one end connected to an internal combustion engine (not shown).
The other end is connected to an air cleaner (not shown). Duct 1
A circular opening 1a is provided on the side wall of the opening 1a.
One end of the communication pipe 2 is arranged at the peripheral edge of the. The communication tube 2 is a cylindrical tube made of synthetic resin, and the partition walls 3 are arranged in a grid pattern so as to partition the inside and form a large number of passages 4 in the axial direction. The communication pipe and the partition may be separate members, and the partition is formed into a so-called honeycomb shape having a diameter substantially the same as the inner diameter of the communication pipe, and fitted into the communication pipe or integrated by adhesion or welding.

The resonance chamber 5 is a box made of synthetic resin, and the other end of the communication pipe 2 is integrally disposed on the upper wall of the resonance chamber 5, and the pipe end is opened inside. On the upper wall of the resonance chamber 5, a groove 6a of a rail body 6 having a substantially U-shaped cross section is faced and arranged in parallel at a predetermined interval. A movable member 7 is reciprocally fitted into the groove 6a of the rail body 6. The movable member 7 is
It is made of synthetic resin and has a substantially rectangular flat plate shape, and a spur gear (rack) that constitutes a driving means is carved in the center of one side to approximately the middle.

A small hole is provided on the upper wall of the resonance chamber 5 so that the inside and the outside communicate with each other between the rail bodies 6, and one end of a gear body 8 which constitutes a driving means by combining a plurality of gears in the small hole is provided. It projects and meshes with the spur gear of the movable member 7. The other end of the gear body 8 is connected to a stepping motor 9 which constitutes a driving means arranged on the upper wall of the resonance chamber 5.

FIG. 3 shows another embodiment in which the movable member, the driving means and the partition wall are different. The movable member 17 is made of metal or synthetic resin, and is formed in a flat plate shape and a substantially fan shape as shown in FIG.
The base end portion is pivotally supported on the upper wall of the resonance chamber 5 and is rotatably disposed in the resonance chamber 5. A crank body 18 is connected to the movable member 17. The crank body 18 is a combination of a plurality of metal crank rods, one side of which is connected to the movable member 17 and the other side of which is rotatably attached to the piston shaft of the air cylinder 19. Reference numeral 13 denotes a partition wall, which is a perforated briquette-like member having a plurality of tubular communication holes formed in the cylindrical body in the axial direction and a large number of passages 14 formed therein. The partition wall may be formed by bundling a plurality of thin tubes and joining the tube walls to each other.

In addition to the above-described embodiment, the movable member is formed into a disk or an elliptical flat plate, and the driving means is a combination of a hydraulic cylinder or a belt and a pulley. is not. Further, the driving means is arranged in the resonance chamber 5 to prevent dust from adhering, the communication pipe 2 is formed as a separate member from the resonance chamber 5, and the partition wall provided in the communication pipe 2 is not the entire region of the three pipes but a part thereof. It may be provided only.

In these variable resonance type silencers, the drive means receives a signal based on the resonance frequency calculated in synchronization with the engine rotation with respect to the engine noise frequency propagated to the duct 1,
The movable members 7 and 17 are slid by a corresponding amount. Only the required number of passages 4 and 14 are covered by the movable members 7 and 17 at the pipe ends of the communication pipes 2 and 12, and the duct 1 and the resonance chamber 5 are communicated with each other by the communication pipes 2 and 12 having a required opening area. Therefore, the variable resonance silencer tunes to the resonance frequency for noise and attenuates the noise.

[0013]

As described above, the variable resonance type silencer of the present invention has a movable member for forming a large number of passages by partition walls in a communication pipe that connects the duct and the resonance chamber and closing the end of the communication pipe. By disposing and connecting to the drive means, the partition wall functions as a side wall corresponding to each position of the movable wall by sequentially closing the pipe end of the communication pipe with the movable member. At the same time, the axially formed passages in the tube function similarly to sequentially replacing single tubes of different open areas throughout the opening.

Therefore, the communication tube does not require a movable wall, and the side wall seal is not required, and the airtightness which influences the sound deadening effect is kept extremely excellent. Further, the movable member may be small enough to close the pipe end of the communication pipe, and the driving means has a small output and is small in size, so that it is not necessary to reinforce the upper wall of the resonance chamber in which the driving means is arranged, and the muffler becomes large. Never. Further, the passages closed by the movable members each function as a side branch type silencer to contribute to the silencing.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a variable resonance silencer of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the variable resonance silencer of the present invention.

4 is a sectional view taken along the line AA of FIG.

FIG. 5 is a cross-sectional view of a conventional variable resonance silencer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 duct 2 communication pipe 3,13 partition wall 4,14 passage 5 resonance chamber 7,17 movable member 8 gear body 9 stepping motor 18 crank body 19 air cylinder

Claims (1)

[Claims] 1. A tubular communication pipe is communicated with a tubular duct, the interior of the communication pipe is partitioned by partition walls to form a large number of passages in the axial direction, and the pipe end of the communication pipe is opened inside the box-shaped resonance chamber. Then, a movable member that blocks the end of the communication pipe is movably disposed in the resonance chamber,
A variable resonance silencer in which a driving member is connected to a movable member.