JPH0619784Y2 - Active canceller system for intake and exhaust pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an active canceller system for intake / exhaust pipes, which is used for silencing intake / exhaust noise of an automobile engine or the like.

(Prior Art) As a conventional active canceller system for intake and exhaust pipes, for example, one described in JP-A-62-48910 is known (FIG. 2). This conventional active canceller system for intake and exhaust pipes has an exhaust pipe 01 whose one end is connected to an engine, and a cancel speaker 03 which is connected to the exhaust pipe 01 through a branch pipe 02.
And the first and second microphones 0 provided in the exhaust pipe 01.
4, 05 and active cancel control means 06 for monitoring exhaust noise based on signals from both microphones 04, 05 and outputting a predetermined control signal to the cancel speaker 03. What is noise with respect to exhaust noise? By outputting the compressional pressure wave of the opposite phase from the cancellation speaker 03,
The sound was damped by the canceling action of both pressure waves.

(Problems to be solved by the invention) However, in such a conventional active canceller system for intake / exhaust pipe, a branch pipe is provided in a part of the (intake / exhaust) pipe to provide a cancel speaker, which is a big problem. The problem of requiring a mounting space,
There is a problem that the (suction) exhaust efficiency deteriorates due to the disturbance of the (suction) exhaust flow due to the branch pipe.

In addition, since the normal speaker is used as the cancel speaker, the speaker is exposed to hot exhaust gas,
There was a problem in terms of performance deterioration, fear of failure, and durability.

(Means for Solving Problems) An object of the present invention is to solve the above problems and to provide an active canceller system for intake / exhaust pipes with a small space, low intake / exhaust resistance, and high heat resistance. In order to achieve this object, in the present invention, one end is connected to an engine, which is a noise source, and an intake / exhaust pipe in which a flow path for intake or exhaust is formed, and a pressure wave is generated for noise of the intake / exhaust pipe. A cancel speaker provided so as to be overlapped with each other, and active cancel control means for monitoring a noise based on a signal input from a microphone provided in the intake / exhaust pipe system and outputting a predetermined control signal to the cancel speaker. The compression loudspeaker having a phase opposite to the pressure wave of the intake / exhaust pipe noise is output from the cancel speaker to cancel the noise by the canceling action of both pressure waves. In the active canceller system for intake / exhaust pipes, the cancel speaker is formed of a cylindrical piezoelectric speaker made of ceramic and having both ends opened, and the piezoelectric speaker is provided with a suction / exhaust pipe whose inner space forms a flow path for intake / exhaust. It is a means characterized by being provided as a part.

(Operation) In the intake / exhaust pipe active canceller system of the present invention, the intake air of the engine or the exhaust gas of the engine flows through the flow path of the intake pipe or the exhaust pipe which is the exhaust pipe.

A cylindrical piezoelectric speaker (cancellation speaker) is provided in a part of the intake / exhaust pipe so that the inner space forms a flow path, and the piezoelectric speaker is provided for intake / exhaust gas flowing inside the piezoelectric speaker. Based on the signal from the active cancellation control means, the speaker outputs a compressional pressure wave having a phase opposite to that of the noise of intake and exhaust, and the noise is silenced by the canceling action of both pressure waves.

Therefore, in the present invention, since the piezoelectric speaker is provided so as to form the intake / exhaust flow path without going through the branch pipe, the intake / exhaust resistance does not occur and the installation space is small.

Further, since this piezoelectric speaker is made of ceramic, it has high heat resistance, and the reliability of performance deterioration due to heat of exhaust gas, failure and durability is improved.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

In describing this embodiment, an exhaust pipe active canceller system used to muffle the exhaust noise of an automobile will be taken as an example.

First, the structure of the embodiment shown in FIG. 1 will be described.

Exhaust pipe active canceller system A of the embodiment
As shown in FIG. 1, the main components are the exhaust pipe 1 and the active cancellation control means 6.

One end of the exhaust pipe 1 is connected to an engine 7 that is a noise source, an exhaust flow path a is formed inside, and a muffler is provided in a portion not shown.

The active cancellation control means 6 is a control means for monitoring the exhaust sound from the engine 7 and outputting a predetermined silencing pressure wave generation signal (1) (actually a minute current) to the piezoelectric speaker 3. The noise detection microphone 4 and the error detection microphone 8 are provided as input means, and the control unit 5 is provided as output means.

The piezoelectric speaker 3 includes a ceramic plate 31 and a metal plate 32.
And the inner diameter is exactly the same as the inner diameter of the exhaust pipe 1 and is formed in a cylindrical shape with both ends opened, and the inner space b thereof forms a part of the exhaust flow path a in the middle of the exhaust pipe 1. It is provided to intervene. Further, between the piezoelectric speaker 3 and the exhaust pipe 1, a highly flexible connecting member 33 is provided. A cover member 34 is provided outside the piezoelectric speaker 3 to seal the piezoelectric speaker 3 from the outside, and glass wool 35 or the like as a sound absorbing material is provided inside the cover member 34. .

When the muffling pressure wave generation signal (l) from the active cancellation control means 6 is input to the piezoelectric speaker 3,
The piezoelectric speaker 3 outputs a compressional pressure wave (hereinafter referred to as a silenced pressure wave) having a phase opposite to that of the pressure wave of the exhaust sound (hereinafter referred to as a noise pressure wave).

The noise detection microphone 4 detects a noise pressure wave and outputs a noise signal (m) to the control unit 5.

The error detection microphone 8 is provided on the outlet side of the exhaust pipe 1, and the error detection microphone 8 outputs a monitor signal (n) of a silencing pressure wave.

The control unit 5 includes the noise detection microphone 4
The control unit 5 is an apparatus for outputting a noise pressure wave having a phase opposite to the noise pressure wave from the piezoelectric speaker 3 based on the noise signal (m) from the A / D converter 5.
1, a memory 52, a CPU 53, a D / A converter 54, graphic equalizers 55 and 56, and a power amplifier 57.

The A / D converter 51 is a converter that converts the noise signal (m) from the noise detection microphone 4 and the waveform from the graphic equalizer 56 into a digital signal that can be processed by the CPU 53.

The memory 52 is a writable and readable memory in which noise pressure wave information is written based on the noise signal from the noise detection microphone 4 and information is written in the middle of calculation in the CPU 53, and calculation processing in the CPU 53 is performed. Necessary information is stored in advance, and if necessary, CP
It is read to U53.

The CPU 53 is a device that performs arithmetic processing on various input information according to predetermined processing conditions.

The D / A converter 54 is a converter that converts a digital signal, which is a calculation result signal from the CPU 53, into an analog signal.

The graphic equalizer 55 includes a D / A converter 54.
It is a pressure wave generator that forms an arbitrary waveform based on an analog signal from.

One graphic equalizer 56 is a pressure wave generator that forms an arbitrary waveform based on the monitor signal (n) from the error detection microphone 8.

The power amplifier 57 is an amplifier that amplifies the pressure wave from the graphic equalizer 55 and outputs a silencing pressure wave generation signal (1) to the piezoelectric speaker 3.

Next, the operation of the embodiment will be described.

First, when the frequency of the noise pressure wave in the exhaust pipe 1 is detected by the noise detection microphone 4 and input to the control unit 5, the piezoelectric speaker 3 is output from the control unit 5.
Then, a muffling pressure wave generation signal (l) for generating a muffling pressure wave having a phase opposite to the detected noise pressure wave is output.

When this muffling pressure wave generation signal (l) is input to the piezoelectric speaker 3, a muffling pressure wave having a phase opposite to that of the noise pressure wave is output from the piezoelectric speaker 3, and the pressure waves cancel each other out.
That is, the noise pressure wave in the exhaust pipe 1 disappears due to the active canceling action, and the exhaust noise is silenced.

Further, since the inner space b of the piezoelectric speaker 3 has exactly the same size as the exhaust flow path a of the exhaust pipe 1, the piezoelectric speaker 3 does not become a resistance of exhaust and the exhaust efficiency is not deteriorated.

The piezoelectric speaker 3 has a ceramic plate 31 and a metal plate 32.
Since it is formed of and, the heat resistance is high, and the reliability of performance deterioration due to exhaust heat, failure and durability is improved.

Further, since the piezoelectric speaker 3 requires almost no space beyond the space for installing the exhaust pipe 1, space saving is achieved.

As described above, in the exhaust pipe active canceller system A of the present embodiment, the effect of not deteriorating the exhaust efficiency, the effect of improving performance, reliability of failure and durability, and the effect of space saving are achieved. Obtained at the same time.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention can be applied even if there is a design change or the like within a range not departing from the gist of the present invention. included.

For example, although an example in which the invention is applied to the exhaust pipe is shown in the embodiment, it may be applied to the intake pipe of the engine.

In addition, although an automobile engine is shown as the engine in the embodiments, it can be applied to any other engine.

(Effects of the Invention) As described above, in the active canceller system for intake and exhaust pipes of the present invention, the cancel speaker is formed of a cylindrical piezoelectric speaker made of ceramic and having both ends opened, and the piezoelectric speaker is provided with an inner space thereof. Since the means provided as a part of the intake / exhaust pipe so as to form a flow path for intake / exhaust, the piezoelectric speaker does not have resistance to intake / exhaust, has high heat resistance, and requires a small mounted speaker. The effect that the efficiency is not deteriorated, the effect that a small space can be achieved, and the effect that the performance is deteriorated due to heat and the reliability against failure and durability are improved are obtained together.

[Brief description of drawings]

FIG. 1 is an overall view showing an exhaust pipe active canceller system of an embodiment of the present invention, and FIG. 2 is an overall view showing a conventional example. 1 ... Exhaust pipe 3 ... Piezoelectric speaker 4 ... Noise detection microphone 6 ... Active cancellation control means 7 ... Engine 8 ... Error detection microphone a ... Exhaust flow path b ... Inner space

Claims (1)

[Scope of utility model registration request] 1. An engine, one end of which is connected to a noise source,
An intake / exhaust pipe in which an intake or exhaust flow path is formed, a cancel speaker provided so that a pressure wave can be superimposed on noise of the intake / exhaust pipe, and a signal input from a microphone provided in the intake / exhaust pipe system And a cancellation control speaker that outputs a predetermined control signal to the cancellation speaker based on the above, and outputs from the cancellation speaker a compression / dense pressure wave having a phase opposite to that of the pressure wave of the intake / exhaust pipe noise. In the active canceller system for intake and exhaust pipes that cancels sound by canceling out both pressure waves, the cancel speaker is formed of a cylindrical piezoelectric speaker made of ceramic and having both ends open, and the piezoelectric speaker has its inner space sucking and exhausting air. Is provided as a part of the intake / exhaust pipe to form a flow path of the intake / exhaust pipe active. Canceller system.