JPH0614009Y2 - Active canceller system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an active canceller system used for silencing noise such as automobile engine sound.

(Prior Art) As a conventional active canceller system, for example, one described in Japanese Patent Application Laid-Open No. 58-214614 (Title of invention, engine exhaust muffler) is known.

This conventional active canceller system B is the sixth
As shown in the figure, the noise outflow pipe 101 connected to the noise source 100, the cancel speaker 102 provided in the noise outflow pipe 101, the noise from the noise source 100 is monitored, and a predetermined control signal is transmitted to the above. The canceling speaker 102 is provided with a control means 103, and a compression pressure wave having a phase opposite to that of the noise from the noise source 100 is output from the canceling speaker 102, so that the pressure waves cancel each other. It was something to do.

(Problems to be solved by the invention) However, in such a conventional active canceller system B, one cancel speaker 1 is used.
Since the sound was muted at 02, there were problems as described below.

The canceling speaker 102 can only mute sound within a sound pressure level region that can be output, and cannot cancel noise with high sound pressure outside the region.

It is not possible to simultaneously eliminate multiple noises with different frequency regions.

The problem of can be solved by using a large cancel speaker with a wide sound pressure level region, but in this case, the speaker installation space is wide and the system is large. It will be.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above-mentioned problems. To achieve this object, the present invention proposes a noise outflow connected to a noise source. A pipe, a cancel speaker provided in the noise outflow pipe, and control means for monitoring the noise from the noise source and outputting a predetermined control signal to the cancel speaker. In an active canceller system that cancels the pressure waves of both pressure waves by canceling the compression and compression pressure waves having a phase opposite to that of the noise, the cancel speaker is placed on the axis orthogonal to the tube axis in the middle of the noise outflow pipe. A plurality of units are installed coaxially.

(Operation) Therefore, in the active canceller system of the present invention, since a plurality of cancellation speakers are coaxially installed on the axis orthogonal to the tube axis in the middle of the noise outflow pipe, the sound pressure level of the noise is increased. By increasing the number of cancellation speakers to be used, a pressure wave with a high sound pressure level is output from the speaker side, so that noise in a high sound pressure level region that cannot be suppressed by one cancellation speaker can be eliminated.

Further, by making the frequency regions of the cancel speakers different, it is possible to simultaneously eliminate noises having different frequency regions.

In addition, since the plurality of cancel speakers are provided coaxially with the axis orthogonal to the tube axis, there is no control complexity, and a smaller cancel speaker is used as compared with the case of using a large cancel speaker. By using a plurality of speakers, the speaker installation space can be reduced and the system can be downsized.

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

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

First, the configuration of the first embodiment will be described.

The active canceller system A of the first embodiment has an exhaust pipe (noise outflow pipe) 1, a cancel speaker 2, and a control means 3 as main constituent elements.

The exhaust pipe 1 is an outflow pipe for exhaust sound from the engine 4 as a noise source, and has one end connected to the exhaust port of the engine 4 and the other end opened outside the vehicle.

Two cancel speakers 2 are installed in the exhaust pipe 1 coaxially with an axis b orthogonal to the tube axis a. The cancel speaker 2 receives a pressure wave generation signal () from the control means 3. Outputs a pressure wave according to the signal level.

The control unit 3 is a unit that monitors the exhaust sound from the engine 4 and outputs a pressure wave generation signal () corresponding to the sound pressure level of the pressure wave of the exhaust sound to the cancel speakers 2 and 2. The pressure sensor 6, the control unit 7, the pressure wave generator 5, and the pressure monitor sensor 10 are the main constituent elements.

The pressure sensor 6 is a sensor for detecting the sound pressure level of the pressure wave of the exhaust sound passing through the exhaust pipe 1 and inputting it to the control unit 7, which is located upstream of the speaker installation position of the exhaust pipe 1. It is provided.

The control unit 7 processes the level signal from the pressure sensor 6 according to a predetermined control condition, and the pressure wave generator 5
Is a control circuit that outputs an instruction signal (n). In this case,
When the pressure wave in the exhaust pipe 1 is input from the pressure sensor 6,
The pressure wave generator 5 is instructed to generate a pressure wave having an opposite phase to the input pressure wave.

Further, the control unit 7 includes an input circuit 70, RA
M71, ROM72, CPU73, clock circuit 74,
The output circuit 75 is provided. The input circuit 70 is a circuit that converts the level signal (m) from the pressure sensor 6 into a signal that can be processed by the CPU 73.

The RAM 71 is a writable and readable memory in which the level signal (m) from the pressure sensor 6 is written and information is written in the middle of calculation in the CPU 73.

The ROM 72 is a write-only memory, in which information necessary for the arithmetic processing in the CPU 73 is stored in advance, and is read out from the CPU 73 when necessary.

The CPU 73 is a device that performs arithmetic processing on various input information according to predetermined processing conditions.

The clock circuit 74 is a circuit for setting the arithmetic processing time in the CPU 73.

The output circuit 75 is a circuit that outputs an instruction signal (n) to the pressure wave generator 5 based on a calculation result signal from the CPU 73.

The pressure wave generator 5 is connected to the cancellation speakers 2 and 2 via an amplifier 9, and is connected to the control unit 7
A predetermined pressure wave is generated by the support from the pressure wave generated here, and the pressure wave generated here is amplified by the amplifier 9 and output as a pressure wave generation signal () from the cancel speaker.

The pressure wave generation signal () from this pressure wave generator 5
Is output to one cancel speaker 2 when the sound pressure level of the pressure wave of the exhaust sound is low, and is output to both cancel speakers 2 and 2 when the sound pressure level is high.

The pressure monitor sensor is a sensor that outputs a monitor signal of a sound pressure wave to the control unit 7,
The exhaust pipe 1 is provided downstream of the speaker installation position.

Next, the operation of the first embodiment will be described.

First, the sound pressure level of the pressure wave in the exhaust pipe 1 is determined by the pressure sensor 6
When detected by and input to the control unit 7, the control unit 7 causes the pressure wave generator 5 to
An instruction signal (n) for generating a pressure wave having a phase opposite to that of the pressure wave detected by the pressure sensor 6 is output, and the pressure wave generator 5 has an opposite phase to the detected pressure wave based on the instruction signal (n). The pressure wave is generated, amplified by the amplifier 9, and then output from the cancel speakers 2 and 2 into the exhaust pipe 1.

At this time, when the sound pressure level of the pressure wave of the exhaust sound is low, the control means 3 outputs the pressure wave generation signal () only to one cancel speaker 2, and as shown in FIG. The cancel speaker 2 outputs a pressure wave (indicated by a virtual line) having a phase opposite to that of the pressure wave of exhaust sound (indicated by a solid line).

Further, when the sound pressure level of the pressure wave of the exhaust sound is high, the control means outputs the pressure wave generation signals () and () to both of the cancel speakers 2 and 2, thereby canceling as shown in FIG. A pressure wave (shown by an imaginary line) having a phase opposite to the pressure wave of the exhaust sound (shown by a solid line) is output from the speakers 2 and 2, and the pressure wave is shown by an oblique line rather than a pressure wave from one cancellation speaker. The sound pressure level is high only in the area.

In this way, when pressure waves of opposite phases from the cancel speakers 2 and 2 hit the pressure waves of the exhaust sound, the pressure waves in the exhaust pipe 1 are canceled by the pressure waves canceling each other out, that is, the active canceling action. It disappears and the exhaust sound from the exhaust port 11 is silenced.

As described above, in the active canceller system A of the first embodiment, the number of cancellation speakers 2 used is increased according to the increase in the sound pressure level of the exhaust sound, so that the pressure wave with the high sound pressure level is output from the speaker side. Therefore, the exhaust sound in the high sound pressure level region that cannot be silenced by one cancel speaker 2 can be silenced.

In addition, since the two cancel speakers 2 and 2 are provided coaxially with the axis b orthogonal to the tube axis a, there is no control complexity, and when one large cancel speaker is used. By using two canceling speakers that are smaller than the above, the speaker installation space can be reduced and the system can be downsized.

Next, a second embodiment using canceling speakers having different frequency regions will be described.

In describing the configuration of the second embodiment, the differences will be described based on the configuration of the first embodiment shown in FIG.

One of the cancel speakers 2 and 2 outputs a pressure wave in a low frequency region, and the other outputs a pressure wave in a high frequency region.

The pressure sensor 6 detects frequencies of different pressure waves in the exhaust pipe 1 and outputs a frequency signal (m) corresponding thereto.

The control unit 7 processes the frequency signal from the pressure sensor 6 according to a predetermined control condition, and the pressure wave generator 5
The instruction signal (n) is output to.

The pressure wave generator 5 is composed of a low frequency side pressure wave generator and a high frequency side pressure wave generator, and both pressure wave generators input an instruction signal (n) from the control unit 7 to generate a pressure wave. Outputs signals () and ().

When the low frequency signal is output from the pressure sensor 6, the low frequency side pressure wave generator outputs a pressure wave generation signal () to the low frequency canceling speaker 2, and the pressure sensor 6 outputs the high frequency signal. Is output, the pressure wave generation signal () is output from the high frequency side pressure wave generator to the high frequency cancellation speaker 2.

Therefore, in the active canceller system of the second embodiment, by using the low frequency cancel speaker 2 and the high frequency cancel speaker 2, as shown in FIG. 4, pressure waves having different frequency regions (shown by solid lines). Can be simultaneously canceled and silenced by the pressure wave (shown by a virtual line) from the speaker.

In the vehicle equipped with the active canceller system of the first and second embodiments, the conventional muffler muffler is not required, and the engine power can be increased.

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, in the embodiment, the description has been given of the first embodiment for silencing high sound pressure noise and the second embodiment for silencing noise in different frequency regions at the same time.
As shown in the figure, four cancel speakers may be provided to integrate the first embodiment and the second embodiment, or the like,
Further, the number of cancel speakers is not limited to two and four.

(Effect of the Invention) As described above, in the active canceller system of the present invention, a plurality of cancellation speakers are installed coaxially with the axis orthogonal to the tube axis in the middle of the noise outflow tube, which makes control complicated. It is possible to eliminate the noise of high sound pressure without increasing the speaker installation space and increasing the system size.

Further, by making the frequency range of the cancel speaker different, it is possible to simultaneously eliminate a plurality of noises having different frequency regions.

[Brief description of drawings]

FIG. 1 is an overall view showing an active canceller system of a first embodiment of the present invention, FIGS. 2 and 3 are operation explanatory views of the first embodiment system of the present invention, and FIG. 4 is a second embodiment of the present invention. Operation explanatory view of the active canceller system, No. 5
FIG. 6 is an explanatory diagram showing another example of the cancel speaker, and FIG. 6 is an explanatory diagram showing a conventional active canceller system. 1 ... Exhaust pipe (noise outflow pipe) 2 ... Cancellation speaker 3 ... Control means

Claims (1)

[Scope of utility model registration request] 1. A noise outflow pipe connected to a noise source, a cancel speaker provided in the noise outflow pipe, and control for monitoring noise from the noise source and outputting a predetermined control signal to the cancel speaker. In the active canceller system for canceling both pressure waves by outputting a compression-dense pressure wave having a phase opposite to that of the noise with respect to the noise from the noise source from the cancellation speaker, The active canceller system is characterized in that a plurality of the noise cancellers are coaxially installed on a shaft orthogonal to the pipe in the middle of the noise discharge pipe.