JPH03279045A - Automotive exhaust sound improving device - Google Patents

Abstract

PURPOSE:To produce an exhaust sound corresponding to a running condition by comparing a sound pressure level on order peak of a voice signal from a second rotation synchronized filter with a target exhaust emitting sound pressure level on decided order peak from engine load and rotating speed, and controlling gain of an amplifier. CONSTITUTION:A voice signal on a decided order from a second rotation synchronized filter 57 is input to a control device 59. In this control device 59, the sound pressure level of the voice signal on the order peak is compared with the target exhaust emitting sound pressure level on the same order peak as the said sound pressure level. So that the sound pressure level on order peak of a voice signal from a second microphone 55 is approached to the target exhaust emitting sound pressure level, the gain of an amplifier 49 is controlled, and the sound pressure level of the voice signal passing through the amplifier 49 from a first microphone 41 is increased or decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automobile exhaust tone improvement device for improving the tone of exhaust sound emitted from an automobile exhaust system.

[Conventional technology]

In general, automobiles are equipped with a muffler or the like in the exhaust system in order to prevent environmental damage caused by exhaust noise emitted from the exhaust system, thereby reducing the exhaust noise to below a regulatory level.

By the way, while a car is running, noise is generated due to engine operation, vibration of the car body, etc. Among the noises heard by the driver inside the car, there are some sounds that are particularly unpleasant. Yes, such unpleasant noises are
For example, in-vehicle noise has been improved by an in-vehicle sound improvement device as disclosed in Japanese Patent Application Laid-Open No. 60-143157.

[Problem to be solved by the invention]

However, in such conventional cars, although the speed, acceleration, etc. are different when the accelerator is fully depressed and when it is not, the exhaust sound does not correspond to the driving situation, and therefore the speed, acceleration feeling, etc. There was a problem in that the driver and the like could feel unsatisfied.

On the other hand, it has been extremely difficult to create exhaust noise that corresponds to such driving conditions by rearranging silencers and the like.

The present invention has been made to solve the above-mentioned problems, and by adding sound to the exhaust sound emitted from the exhaust system, it is possible to create an exhaust tone that corresponds to the driving condition. The purpose is to provide a timbre improvement device.

[Means to solve the problem]

The automobile exhaust tone improvement device of the present invention has a first system that collects the exhaust sound immediately after it is emitted from the engine and converts it into an audio signal.
a microphone; a first rotary synchronous filter that blocks the passage of audio signals other than frequency components of a specific order determined by the rotational speed of the engine among the audio signals from the first microphone and decomposes the audio signal into each order component; , an amplifier that increases or decreases the sound pressure level of the audio signal of a predetermined order from the first rotary synchronous filter, and an amplifier that converts the audio signal that has passed through this amplifier into sound and generates sound, and generates a sound that is similar to the exhaust sound from the automobile exhaust system. a speaker for synthesizing; a second microphone for collecting a synthesized sound obtained by synthesizing the sound from the speaker and the exhaust sound from the exhaust system of the automobile and converting it into an audio signal; a second rotary synchronous filter that blocks the passage of audio signals other than frequency components of a specific order determined by the engine rotational speed and decomposes the audio signal into each order component; A control device receives a signal and controls the gain of the amplifier by comparing the sound pressure level at the order peak of the audio signal with a target exhaust discharge sound sound pressure level at the order peak determined from the engine load and rotation speed. It is equipped with the following.

[For production]

In the automobile exhaust tone improvement device of the present invention, engine speed and engine load are input to the control device, and a target exhaust discharge sound sound pressure level corresponding to the engine speed and engine load is derived within the control device.

This target exhaust exhaust sound sound pressure level is determined as the sound pressure level at the target order peak of the sound emitted from the rear of the car, and the sound pressure level at the order peak of the sound emitted from the rear of the car is the target exhaust exhaust sound pressure level. When it comes to the sound pressure level of exhaust sound, exhaust sound is generated in response to driving conditions such as speed and acceleration, and the sound pressure level is determined to be an exhaust sound level that satisfies the driver and the like.

On the other hand, the exhaust sound immediately after being emitted from the engine is collected by the first microphone and converted into an audio signal. Among the audio signals from the first microphone, audio other than the frequency component of a specific order determined by the engine rotation speed is Passage of the signal is blocked by the first rotary synchronous filter, and the audio signal that has passed through this filter is decomposed into each order component.

Then, the audio signal of a predetermined order decomposed by the first rotary synchronous filter is input to an amplifier whose gain is controlled by a control device, the sound pressure level of the audio signal is increased or decreased, and the audio signal is converted into sound by a speaker. This sound is then synthesized with the exhaust sound from the car's exhaust system.

A synthesized sound obtained by combining the sound from the speaker and the exhaust sound from the exhaust system of the automobile is collected by the second microphone and converted into an audio signal.

Among the audio signals from the second microphone, passage of audio signals other than frequency components of a specific order determined by the engine rotation speed is blocked by a second rotational synchronous filter,
The audio signal is decomposed into each order component.

The audio signal at a predetermined order from this second rotary synchronous filter is input to the control device, and within this control device, the sound pressure level at the order peak of the audio signal and the target exhaust gas at the order peak of the same order as this sound pressure level are determined. The gain of the amplifier is controlled so that the sound pressure level at the order peak of the sound signal from the second microphone approaches the target exhaust sound pressure level. The sound pressure level of the audio signal from the microphone is increased or decreased.

That is, the control device increases the gain of the amplifier when the target exhaust discharge sound sound pressure level is higher, and decreases the gain of the amplifier when the target exhaust discharge sound sound pressure level is lower. The sound pressure level of a synthesized sound obtained by combining the sound from the speaker and the exhaust sound from the exhaust system of the automobile is controlled so as to approach the target exhaust discharge sound sound pressure level.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of the present invention will be described with reference to an embodiment shown in the drawings.

FIG. 1 shows an embodiment of an automobile exhaust tone improvement device according to the present invention, and in the figure, reference numeral 31 indicates an engine mounted on the vehicle.

An exhaust system 33 is connected to this engine 31 to discharge exhaust gas, and this exhaust system 33 includes a catalytic converter 35 for purifying the exhaust gas, a bridge muffler 37 for reducing exhaust noise. Muffler 39 is installed.

The exhaust system 33 extends to the rear of the vehicle, and its rear end is opened toward the rear of the vehicle.

A first microphone 41 is arranged on the upstream side of the exhaust system 33 to collect exhaust sound immediately after being exhausted from the engine 31 and convert it into an audio signal.

The first microphone 41 is connected to a first rotation synchronization filter 43 that blocks the passage of audio signals other than frequency components of a specific order determined by the rotational speed of the engine 31 and decomposes the audio signal into each order component.

Further, a rotation speed sensor 45 that measures the rotation speed of the engine 31 is connected to the engine 31, and a converter 47 that converts a pulse signal from the rotation speed sensor 45 into a voltage is connected to the rotation speed sensor 45. This converter 47 is connected to the first rotation synchronous filter 43.

An amplifier 49 that increases or decreases the sound pressure level of the audio signal at a predetermined order is connected to the first rotation synchronous filter 43.

This amplifier 49 is connected to a speaker 51 that converts the audio signal into sound and produces sound, and the sound from this speaker 51 is synthesized with the exhaust sound from the exhaust system 33 of the automobile.

This speaker 51 is arranged at the rear end of the exhaust system 33. Further, an acoustic conduit 53 is formed in the speaker 51, and the tip of this acoustic conduit 53 is opened in the same direction as the rear end of the exhaust system 33.

A second microphone 5 is provided in the acoustic conduit 53 of the speaker 51 to collect a synthesized sound obtained by combining the sound from the speaker 51 and the exhaust sound from the exhaust system 33 of the automobile, and convert it into an audio signal.
5 is fixed.

The second microphone 55 is connected to the engine 3 out of the audio signal.
It is connected to a second rotary synchronous filter 57 that blocks the passage of audio signals other than frequency components of a specific order determined by the number of rotations of 1 and decomposes the audio signal into each order component.

The second rotation synchronous filter 57 and the first rotation synchronous filter 43 are, for example, voltage-tuned filters. The device is composed of a bandpass filter that passes a third-order frequency component and a bypass filter that passes a 0.5-order or higher frequency component. It is connected to the converter 47 for conversion, and allows the same order component as the first rotation synchronous filter 43 to pass therethrough.

Further, the second rotation synchronous filter 57 receives an audio signal of a predetermined order from the second rotation synchronous filter 57, and the order peak determined from the sound pressure level at the order peak of the audio signal and the engine load and rotation speed. The target exhaust discharge sound pressure level is compared with the amplifier 49.
A control device 59 is connected to control the gain of.

Between the second rotation synchronous filter 57 and the control device 59,
An A/D converter 61 is arranged, and a second microphone 55
An audio signal from the controller 59 is input as numerical data to the control device 59.

Further, the control device 59 is connected to, for example, a boost pressure sensor connected to the engine 31 that senses the engine load. In addition, the converter 47 and the control device 5
9 is connected, and the engine speed is input to the control device 59.

Further, the control device 59 takes in as data a target exhaust discharge sound pressure level determined by the engine rotation speed and engine load. Note that the target exhaust discharge sound sound pressure level does not necessarily have to be stored in the control device 59 as data, and can be derived in the control device 59 by substituting the rotation speed and engine load of the engine 31 into a calculation formula, for example. Good.

This target exhaust exhaust sound sound pressure level is determined as the sound pressure level at the target order peak of the sound emitted from the rear of the car, and the sound pressure level at the order peak of the sound emitted from the rear of the car is the target exhaust exhaust sound pressure level. When it comes to the sound pressure level of exhaust sound, exhaust sound is generated in response to driving conditions such as speed and acceleration, and the sound pressure level is determined to be an exhaust sound level that satisfies the driver and the like.

Further, the order components of the audio signal passing through the first rotation synchronization filter 43 and the second rotation synchronization filter 57 are the order components of the order in which the target exhaust discharge sound sound pressure level exists.

In FIG. 1, solid lines indicate transmission paths of electrical signals based on sound, and broken lines indicate transmission paths of electrical signals based on other information.

In the automobile exhaust tone improvement device configured as described above, as shown in FIG. , a target exhaust discharge sound pressure level corresponding to the engine speed and engine load is derived.

This target exhaust discharge sound pressure level is varied to various values depending on the engine speed and load, for example, as shown in FIGS. 3 to 5.

On the other hand, the exhaust sound immediately after being emitted from the engine 31 is the first
The first rotational synchronous filter 43 blocks the passage of audio signals other than frequency components of a specific order determined by the engine rotation speed, which are collected by the microphone 41 and converted into audio signals. , the audio signal is decomposed into each order component.

Then, the audio signal of a predetermined order decomposed by the first rotary synchronous filter 43 is input to the amplifier 49 whose gain is controlled by the control device 59, the sound pressure level of the audio signal is increased or decreased, and the audio signal is output by the speaker 51. The sound is converted into sound, is emitted, and is synthesized with the exhaust sound from the exhaust system 33 of the automobile.

Further, a synthesized sound obtained by combining the sound from the speaker 51 and the exhaust sound from the exhaust system 33 of the automobile is collected by the second microphone 55 and converted into an audio signal.

Among the audio signals from the second microphone 55, the passage of audio signals other than frequency components of a specific order determined by the rotation speed of the engine 31 is blocked by the second rotation synchronization filter 57, and the audio signal is decomposed into each order component. Ru. That is, the audio signal from the second microphone 55 is decomposed into components of the same order as the audio signal from the first microphone 41.

The audio signal at a predetermined order from the second rotation synchronous filter 57 is inputted to the control device 59 as numerical data, and within the second control device 59, the sound pressure level at the order peak of the audio signal, the engine load and the rotation speed are determined. The sound pressure level of the amplifier 49 at the order peak determined from the second microphone 55 is compared with the target exhaust discharge sound sound pressure level at the order peak determined from the second microphone 55. The gain is controlled, and the sound pressure level of the audio signal from the first microphone 41 passing through the amplifier 49 is increased or decreased.

That is, the control device 59 increases the gain of the amplifier 49 when the target exhaust discharge sound sound pressure level is larger, and increases the gain of the amplifier 49 when the target exhaust discharge sound sound pressure level is smaller. The sound pressure level of the synthesized sound obtained by combining the sound from the speaker 51 and the exhaust sound from the exhaust system 33 of the automobile is controlled so as to approach the target exhaust discharge sound sound pressure level.

Therefore, by adding sound to the exhaust sound emitted from the exhaust system 33, it is possible to create an exhaust tone that corresponds to the driving condition, thereby giving the driver a sufficient sense of speed, acceleration, etc. I can do it.

In addition, the amplifier 49 performs feedback control so that the sound pressure level at the order peak of the audio signal from the second microphone 55 approaches the target exhaust discharge sound sound pressure level.
gain is controlled, and the sound pressure level of the audio signal from the first microphone 41 passing through the amplifier 49 is increased/decreased, so that the sound pressure level of the sound signal from the first microphone 41 that passes through the amplifier 49 is constantly controlled to be close to the target exhaust discharge sound sound pressure level, and the optimal sound pressure level corresponding to the operating condition is maintained. Can create exhaust tone.

Furthermore, the exhaust sound immediately after being discharged from the engine 31 is used as a sampling sound source, and the sound pressure level of this sound source is measured by the amplifier 4.
9, it is possible to obtain an almost pure exhaust sound that is not mixed with the silencing characteristics of the muffler, and it is possible to create an optimal exhaust tone corresponding to the operating condition.

In addition, in this example, the exhaust sound from the rear of the car is
It can be changed by changing the target exhaust discharge sound sound pressure level in the control device 59, and the exhaust sound can be easily changed without improving the exhaust system 33.

[Effects of the Invention] In the automobile exhaust tone improvement device of the present invention, the exhaust sound immediately after being emitted from the engine is collected by the first microphone and converted into an audio signal, and among the audio signals from the first microphone, Passage of audio signals other than frequency components of a specific order determined by the engine rotational speed is blocked by the first rotational periodic filter, and the audio signal is decomposed into each order component and sent to an amplifier whose gain is controlled by a control device. The sound pressure level of the input audio signal is increased or decreased, and the audio signal is converted into sound by a speaker and produced, and is synthesized with the exhaust sound from the exhaust system of the automobile.

On the other hand, a synthesized sound that is a combination of the sound from the speaker and the exhaust sound from the exhaust system of the car is collected by a second microphone and converted into an audio signal. Passage of the audio signal other than the components is blocked by the second rotary periodic filter, the audio signal is decomposed into each order component, the audio signal at a predetermined order is input to the control device, and within this control device, the audio signal is The sound pressure level at the order peak is compared with the target exhaust discharge sound sound pressure level at the order peak determined from the engine load and rotation speed, and the sound pressure level at the order peak of the audio signal from the second microphone is determined as the target exhaust discharge sound pressure level. The gain of the amplifier is controlled by the control device so that the sound pressure level of the audio signal from the first microphone passing through the amplifier is increased or decreased so as to approach the sound pressure level.

Therefore, by adding sound to the exhaust sound emitted from the exhaust system, it is possible to easily create an exhaust tone that corresponds to the operating state.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of an automobile exhaust tone improvement device according to the present invention. FIG. 2 is a flowchart showing an example of control by the control device shown in FIG. FIGS. 3 to 5 are graphs showing target exhaust discharge sound pressure levels with respect to engine speed and engine load. [Explanation of symbols of main parts] 31... Engine 33... Exhaust system 41... First microphone 43... First rotating periodic filter 49... Amplifier 51... Speaker 55... -Second microphone 57...second rotation periodic filter 59...control device. Diagram

Claims (1)

[Claims] (1) A first microphone that collects the exhaust sound immediately after it is emitted from the engine and converts it into an audio signal, and audio other than the frequency component of a specific order determined by the engine speed among the audio signals from this first microphone. a first rotary synchronous filter that blocks passage of the signal and decomposes the audio signal into order components; an amplifier that increases or decreases the sound pressure level of the audio signal of a predetermined order from the first rotary synchronous filter; A speaker that converts the voice signal into sound and generates sound and synthesizes it with the exhaust sound from the exhaust system of the car, and a synthesized sound that combines the sound from this speaker and the exhaust sound from the exhaust system of the car is collected. and a second microphone that converts the audio signal into an audio signal, which prevents the passage of audio signals other than frequency components of a specific order determined by the rotation speed of the engine among the audio signals from the second microphone, and converts the audio signal into audio signals for each order component. a second rotary synchronous filter to be disassembled;
An audio signal at a predetermined order from this second rotation synchronous filter is input, and the sound pressure level at the order peak of this audio signal is compared with the target exhaust discharge sound sound pressure level at the order peak determined from the engine load and rotation speed. and a control device for controlling the gain of the amplifier.