JPH07287583A - Active muffler - Google Patents

Abstract

PURPOSE:To provide an active muffler always performing excellent active muffling even when ambient temp. changes. CONSTITUTION:In the active muffler 1 outputting a sound with a phase opposite to an input noise by an operation process by an operation coefficient decided by a noise transfer function between a noise detection part and a muffling sound generation part from a muffling sound generation means 11 and muffling by sound wave interference, the device is provided with a storage means 21 storing the noise transfer function corresponding at every ambient temp. and a temp. detection means 19 detecting the ambient temp., and the noise transfer function corresponding to the ambient temp. detected by the temp. detection means 19 is read out from the storage means 21, and the operation coefficient is revised based on the read out noise transfer function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active silencer,
In particular, the present invention relates to an active silencer used as a silencer for NC machine tools.

[0002]

2. Description of the Related Art JP-A-63-5696 and JP-A-2
As disclosed in Japanese Patent Laid-Open No. 92099, noise generated by a noise source is detected by noise detecting means such as a microphone arranged at a specific position, and the noise is transmitted between the noise detecting section and the noise reducing sound generating section. There is already known an active muffling device that performs sound processing with a calculation coefficient determined by a function to output a sound having a phase opposite to that of the input noise from a sound deadening sound generation unit and muffle the sound by sound wave interference.

[0003]

Since the noise transfer function between the noise detecting section and the sound-deadening sound generating section changes depending on the ambient temperature, if this noise transfer function is fixedly set, the ambient temperature The calculation coefficient deviates from the conforming value due to the change of
Active silencers do not provide good active silence.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an active muffling device that always performs good active muffling even when the ambient temperature changes.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the above-described object is obtained by performing an operation process based on an operation coefficient determined by a noise transfer function between a noise detection section and a sound-deadening sound generation section, and inversely calculating the input noise. In an active muffling apparatus that outputs a sound of a phase from a sound deadening sound generation unit and muffles sound by sound wave interference, a storage unit that stores a noise transfer function corresponding to each ambient temperature, and a temperature detection unit that detects the ambient temperature. Have
A noise canceling function corresponding to the ambient temperature detected by the temperature detecting means is read from the storage means, and the operation coefficient is changed based on the read noise transfer function. To be done.

Further, the active muffler according to the present invention is used as a muffler for an NC machine tool, and is characterized in that it is connected to the NC device so as to be communicable therewith and uses a storage means incorporated in the NC device as the storage means. Good.

[0007]

According to the above-mentioned structure, the calculation coefficient is set according to the ambient temperature detected by the temperature detecting means, and the calculation coefficient is set between the noise detecting section and the sound deadening sound generating section regardless of the change of the ambient temperature. It will always match the actual noise transfer function of.

When the active silencer is used as a silencer for an NC machine tool, the noise transfer function corresponding to the ambient temperature is stored in the storage means of the NC device, and the active silencer reads the noise transfer function from this. .

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of an active muffler according to the present invention.

The active silencer is generally designated by the numeral 1 in FIG. The active noise suppressor 1 has a noise detecting means 3 such as a microphone, an interface circuit 5 for inputting a noise signal from the noise detecting means 3, and a control for outputting a sound having a phase opposite to the input noise by a calculation process using a predetermined calculation coefficient. Digital filter 7 to be performed, and digital filter 7
The interface circuit 9 for inputting the output signal of 1 and the sound generating means 11 such as a speaker which receives the signal from the interface circuit 9 and outputs a sound having a phase opposite to the input noise.

The active silencer 1 has an interface circuit 13
Is connected to the control computer 17 of the NC device 15 so as to be capable of bidirectional communication. A temperature sensor 19 is connected to the interface circuit 13.

The NC device 15 includes a control computer 17
And a storage means 21 using a non-volatile memory, an I / O circuit 23, a servo amplifier 27 of a servo motor 25, and an operation panel 29. The control computer 17 issues a drive command to the servo amplifier 27 by program analysis. Output.

The storage means 21 stores a system program for numerical control and also stores a noise transfer function corresponding to each ambient temperature. This noise transfer function is a noise transfer function between the noise detection unit and the sound deadening sound generation unit.

The control computer 17 includes a temperature sensor 19
The ambient temperature detected by is fetched from the interface circuit 13, the noise transfer function corresponding to the ambient temperature is read from the storage means 21, and transferred to the digital filter 7 via the interface circuit 13.

As a result, the digital filter 7 determines the calculation coefficient based on the noise transfer function from the control computer 17, and performs the control of outputting the sound having the opposite phase to the input noise by the calculation processing by the calculation coefficient.

In this way, the calculation coefficient of the digital filter 7 is adaptively set according to the ambient temperature, so that good active muffling is always performed regardless of the change in the ambient temperature.

In the above, the present invention has been described in detail with respect to a specific embodiment, but the present invention is not limited to this, and various embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

[0019]

As can be understood from the above description, according to the active muffler of the present invention, the calculation coefficient is set according to the ambient temperature detected by the temperature detecting means, and the calculation coefficient is concerned with the change of the ambient temperature. Since it always matches the actual noise transfer function between the noise detector and the sound-deadening sound generator, good active noise suppression is always performed even if the ambient temperature changes.

When the active muffler is used as a muffler for NC machine tools, the noise transfer function corresponding to the ambient temperature is stored in the storage means of the NC device so that the NC device has a large capacity memory. Is effectively used and there is no need for a memory dedicated to the noise transfer function.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an active silencer according to the present invention.

[Explanation of symbols]

 1 Active Noise Suppressor 3 Noise Detection Means 7 Digital Filter 11 Sound Generation Means 15 NC Device 17 Control Computer 19 Temperature Sensor 21 Storage Means

Claims (2)

[Claims] 1. A sound producing unit for noise elimination outputs a sound having a phase opposite to that of the input noise by a calculation process using a calculation coefficient determined by a noise transfer function between the noise detecting unit and the sound producing unit for noise reduction, and by sound wave interference. In an active muffling device that muffles noise, it has a storage unit that stores a noise transfer function corresponding to each ambient temperature, and a temperature detection unit that detects the ambient temperature,
An active silencer, which is configured to read a noise transfer function corresponding to an ambient temperature detected by the temperature detecting means from the storage means and change the calculation coefficient based on the read noise transfer function. 2. An active muffler used as a muffler for an NC machine tool, which is communicably connected to the NC device and uses a memory means incorporated in the NC device as the memory means.