JP2528968Y2 - Engine intake noise reduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a device for reducing intake noise of an engine.

2. Description of the Related Art It is well known to attach a silencer to an engine intake system in order to reduce engine intake noise. As this silencer, various types of resonance type silencers have been proposed, for example, in Japanese Utility Model Laid-Open No. 59-102977.

(Problems to be solved by the invention) However, the conventional resonance type silencer forms a volume chamber around the intake pipe and communicates with the inside to resonate with the intake pulsation in a specific frequency range to reduce noise. Is attenuated.

However, in the case of the type in which the volume chamber is formed around the intake pipe in this way, it may not be possible to mount the intake pipe due to interference with engine components due to the radial space of the intake pipe.

The present invention aims to solve such a problem.

(Means for Solving the Problems) Therefore, in the present invention, a sound deadening pipe having the other end closed is opened substantially at the center of the intake pipe of the engine, and the length of the sound deadening pipe is set to approximately half of the total length of the intake pipe. At the same time, this silencing pipe was arranged inside the intake pipe in parallel with the inner wall.

(Operation) Based on the relationship between the engine speed and the effective length of the intake pipe, resonance occurs in the intake pipe in a frequency region where the length of the intake pipe is an integral multiple of a half wavelength of the intake pulsation wave. The amplitude of the resonance wave is maximum at the center of the intake pipe, that is, at the position where the silencing pipe is open, and the sound pressure level is the highest. By opening the silencing pipe in this portion and setting the total length of the silencing pipe to half of the resonance wave period, resonance occurs inside the silencing pipe and consumes vibration energy.

Since the muffler pipe is arranged inside the intake pipe in parallel with the inner wall, the space required to arrange the muffler pipe can be reduced compared to when the muffler pipe is arranged on the outer circumference of the intake pipe, and the degree of freedom of mounting in the engine room and the like is increased . Also,
Since it is arranged in parallel with the inner wall of the intake pipe, it does not obstruct the flow of intake air.

(Example) The example of this invention is described based on drawing.

1, 2 and 3, an intake pipe 2 for taking in outside air is provided, and air from the intake pipe 2 is filtered by an air cleaner 3 and then sucked into the engine body. In addition, 4 is an exhaust pipe in the figure, 5 is a muffler.

A silencing pipe 6 is provided in the middle of the intake pipe 2. As shown in FIGS. 2 and 3, the silencing pipe 6 opens substantially at the center of the intake pipe 2 and is formed by closing the other end. It is set to be half. However, silencing pipe 6
Opening position is 0.35 ~, where L is the total length of the intake pipe 2.
There is an effect even if it is set in the range of 0.65L. The silencing pipe 6 is arranged inside the intake pipe 2 in parallel with the inner wall.

And it is desirable that the silencing pipe 6 is disposed at least above the horizontal plane with respect to the center of the intake pipe 2,
This prevents water droplets from accumulating inside the silencing pipe 6.

 The configuration is as described above. Next, the operation will be described.

The intake pressure changes pulsatingly with the operation of the engine, and the pulsation frequency corresponds to the engine speed. Due to the relationship between the effective length of the intake pipe 2 and the pulsation frequency, resonance occurs in a specific frequency range, that is, a frequency range in which the length of the intake pipe 2 is an integral multiple of a half wavelength of the intake pulsation wave.

In this embodiment, the effective length of the intake pipe 2 is set so as to resonate in a relatively low-speed rotation range of the engine, so that low-frequency muffled noise is reduced intensively.

The amplitude of the resonance wave becomes maximum at the center of the intake pipe 2, that is, at the position where the sound deadening pipe 6 is opened, and the sound pressure level becomes highest.

By opening the muffling pipe 6 at this portion and making the total length of the muffling pipe 6 approximately half that of the intake pipe 2, resonance occurs inside the muffling pipe 6 with respect to the resonance wave, and the vibration action Consume.

As a result, relatively low-frequency intake noise is effectively reduced.

In addition, moisture may be contained in the intake air, but since the silencing pipe 6 opened in the middle of the intake pipe 2 is located above the horizontal plane, water does not enter inside,
There is no need to worry about corrosion.

Then, a sound absorbing material is attached to the inner peripheral surface of the sound absorbing pipe 6 to form a sound absorbing layer 10.

Examples of the sound absorbing material include urethane, sintered aluminum alloy, glass wool, rock wool, steel wool, felt and the like.

When the sound absorbing layer 10 is formed in this manner, the effect of attenuating noise increases, and the noise level in the target silencing region is reduced to the first level.
Can be reduced as compared with the embodiment.

(Effects of the Invention) As described above, according to the present invention, the sound deadening pipe is opened at the center of the suction pipe where the amplitude of the resonance wave generated inside the suction pipe, in other words, the sound pressure level is maximized, and the sound deadening pipe is opened. Is set to half of the resonance wave period, the noise reduction pipe resonates with a pulsating wave of a predetermined frequency, so that vibration energy is consumed and intake noise can be effectively reduced.

In addition, since the muffling pipe is arranged in parallel with the inner wall inside the intake pipe, the arrangement space is reduced and the resistance of the intake flow is small.

[Brief description of the drawings]

1 is a perspective view schematically showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the embodiment, and FIG. 3 is a side view of the same. 2… Intake pipe, 6… Mute pipe, 10… Sound absorption layer.

Claims (2)

(57) [Scope of request for utility model registration] A muffler pipe having the other end closed is opened substantially at the center of the intake pipe of the engine, and the length of the muffler pipe is set to substantially half of the total length of the intake pipe. An intake air noise reduction device for an engine, wherein the device is disposed inside and in parallel with an inner wall. 2. The engine intake noise reducing device according to claim 1, wherein the sound absorbing pipe has a sound absorbing layer formed by attaching a sound absorbing material inside the sound absorbing pipe.