JPH09158799A - Active noise control device for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of the effect to reduce the air intake noise by the characteristic change of a speaker due to a temperature drop in an air intake system. SOLUTION: The temperature Ta in an air intake system is detected (S1). When the temperature Ta in the air intake system rises, the intensity of the sound wave generated from a speaker is reduced, while the response delay of the speaker is increased when the temperature Ta in the air intake system is dropped. The drive signal is increasingly corrected (S3) by the gain correction value CG so as to complement the reduction in the intensity due to the rise of the temperature Ta. The phase is advanced by the phase correction value CP so as to complement the increase in the response delay due to the drop of the temperature Ta (S4).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active noise control apparatus for an automobile, which actively reduces noise in an automobile by interference of a separately generated sound wave, and more particularly to a technique for reducing intake noise of an engine.

[0002]

2. Description of the Related Art In recent years, a technique called active noise control has been proposed as a technique for ensuring quietness of an automobile. The active noise control means that a noise (primary sound) in an automobile is converted into another sound wave (secondary sound) having the same amplitude and opposite phase to the noise (primary sound) in view of the fact that the sound is a kind of wave phenomenon in which a change in the density of air propagates in the air. Sound) to cancel the primary sound.

In order to reduce the intake noise generated by the intake pulsation of the engine by the active noise control, a speaker is installed in the intake system which is a noise source and the intake noise (the intake pulsation noise is generated). ) Is detected by a microphone or the like, and a sound wave that cancels the detected intake noise is generated from the speaker, whereby the intake noise can be positively reduced.

[0004]

By the way, in the active noise control, the generated intensity characteristic and the response characteristic of the speaker for generating the secondary sound change due to the influence of the temperature change in the intake system. There was a fear that the muffling effect of the period could not be obtained. In other words, the intensity of the sound wave obtained for a given drive signal may change due to temperature changes, making it impossible to secure the energy necessary to cancel the intake noise, or conversely, excessive energy may be generated. In addition, since the response characteristics change depending on the temperature, it is not possible to correctly generate a sound wave having an opposite phase to the intake noise, and thus it may not be possible to exert a sufficient canceling effect. It was there.

The present invention has been made in view of the above problems, and even if the intensity characteristics and response characteristics of the sound generated by the sound wave generating means such as a speaker change due to the influence of the temperature in the intake system, it is expected. The purpose is to be able to exert the silencing effect of.

[0006]

Therefore, an active noise control system for an automobile according to the invention of claim 1 cancels the intake noise by generating a sound wave having the same amplitude and opposite phase as the intake noise of the engine. The controller is configured as shown in FIG. In FIG. 1, the sound wave generating means is means for generating sound waves in the intake system of the engine, and the intake noise detecting means is means for detecting intake noise of the engine. The sound wave generation control means drives and controls the sound wave generation means based on the intake noise detected by the intake noise detection means so as to generate a sound wave for canceling the intake noise.

On the other hand, the intake system internal temperature detecting means detects the temperature in the intake system, and the control characteristic correcting means controls the sound wave generation based on the temperature in the intake system detected by the intake system internal temperature detecting means. At least one of the gain characteristic and the phase control characteristic in the means is corrected. According to such a configuration, the sound wave generating means is affected by the temperature in the intake system and changes its generation intensity characteristic and response characteristic, so by detecting the temperature in the intake system, the characteristic change is estimated, In order to generate a desired sound wave in response to such a characteristic change, at least one of the gain characteristic and the phase control characteristic at the time of driving and controlling the sound wave generating means is modified so that the desired silencing effect can be maintained. .

According to a second aspect of the present invention, there is provided an active noise control device for an automobile, which cancels the intake noise by generating sound waves having the same amplitude and opposite phase as the intake noise of the engine.
It is configured as shown in FIG. In FIG. 2, the sound wave generating means is a means for generating a sound wave in the intake system of the engine, and the intake noise detecting means is a means for detecting the intake noise of the engine. The sound wave generation control means drives and controls the sound wave generation means based on the intake noise detected by the intake noise detection means so as to generate a sound wave for canceling the intake noise.

On the other hand, the specific frequency intensity detecting means detects the intensity of the sound wave of the specific frequency generated by the sound wave generating means, and the gain characteristic correcting means detects the intensity detected by the specific frequency strength detecting means and the reference intensity. The gain characteristic in the sound wave generation control means is corrected based on the comparison of. According to such a configuration, by detecting the intensity of the sound wave of the specific frequency generated from the sound wave generating means, it is possible to detect the change in the strength of the sound wave actually obtained with respect to the drive signal, which is caused by the temperature change in the intake system. If the gain is corrected based on this, the energy required to cancel the intake noise can be accurately generated.

According to a third aspect of the invention, the specific frequency is a frequency that does not interfere with intake noise. According to this configuration, even if intake noise is present, the intensity of the sound wave generated by the sound wave generator can be detected with high accuracy. According to a fourth aspect of the present invention, there is provided a canceling residual sound detecting means for detecting a canceling residual sound of the intake noise, and the specific frequency intensity detecting means performs the frequency analysis of a detection result of the canceling residual sound detecting means to determine the specific frequency. It is configured to detect the intensity of.

According to this structure, the characteristics of the sound wave generating means can be detected while the cancellation residual sound is detected by the cancellation residual sound means. The invention according to claim 5 is an active noise control device for an automobile, which generates a sound wave having the same amplitude as and an opposite phase to the intake noise of the engine to cancel the intake noise, and is configured as shown in FIG.

In FIG. 3, the sound wave generating means is means for generating sound waves in the intake system of the engine, and the intake noise detecting means is means for detecting the intake noise of the engine. The sound wave generation control means drives and controls the sound wave generation means based on the intake noise detected by the intake noise detection means so as to generate a sound wave for canceling the intake noise.

On the other hand, the response delay time detecting means detects the response delay time of the sound wave generating means, and the phase control characteristic correcting means compares the response delay time detected by the response delay time detecting means with the reference delay time. The phase control characteristic in the sound wave generation control means is corrected based on the above. With such a configuration, by detecting the response delay time of the sound wave generating means, a change in the response delay time caused by, for example, a temperature change in the intake system can be detected, and the phase control characteristic can be corrected based on this. Thus, it is possible to accurately generate a sound wave having a phase opposite to the intake noise.

According to a sixth aspect of the present invention, there is provided a cancellation residual sound detecting means for detecting a cancellation residual sound of the intake noise.
The response delay time detection means detects the response delay time as a time until the sound wave generated by the sound wave generation means is detected by the cancellation residual sound detection means. With such a configuration, the response delay time in the sound wave generating unit can be easily detected by measuring the time from the drive control of the sound wave generating unit to the actual detection of the sound wave.

[0015]

Embodiments of the present invention will be described below. FIG. 4 shows a system configuration of an engine mounted on an automobile. Air is taken into the engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4, an intake collector 5, and an intake manifold 6. .

The throttle chamber 4 is provided with a throttle valve 7 which works in conjunction with an accelerator pedal (not shown) to adjust the amount of intake air of the engine 1. Each branch portion of the intake manifold 6 is provided with an electromagnetic fuel injection valve 8 for each cylinder. The fuel which is fed from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator is introduced into the intake manifold 6. Inject supply.

The fuel injection valve 8 is intermittently driven to open in response to an injection pulse signal sent from a control unit 9 having a built-in microcomputer, and has a pulse width of the injection pulse signal calculated by the control unit 9. The fuel injection amount is controlled. Intake duct 3 upstream of the throttle chamber 4
Is provided with an air flow meter 10 for detecting the intake air flow rate Qa of the engine 1. The air flow meter
Reference numeral 10 is for detecting the intake air flow rate Qa of the engine as a mass flow rate based on, for example, a change in the resistance value of the heat-sensitive resistance arranged in the intake duct.

In the present embodiment, since the detection signal of the air flow meter 10 is used as a signal correlating with the intake pulsation noise in the active noise control described later, the air flow meter 10 also serves as the intake noise detecting means. is there. However, a structure in which a microphone is separately provided as the intake noise detection means may be used. Further, a crank angle sensor 11 for extracting a reference angle signal for each reference crank angle and a unit angle signal for each unit crank angle from the crankshaft or the camshaft is provided, and a detection signal from the crank angle sensor 11 is provided. Based on the engine speed Ne
Can be calculated.

Further, the throttle sensor 12 for detecting the opening TVO of the throttle valve 7, the engine coolant temperature T
A water temperature sensor 13 for detecting w is provided. The control unit 9 calculates the engine speed Ne based on the intake air flow rate Qa detected by the air flow meter 10 and the detection signal from the crank angle sensor 11.
The basic injection pulse width Tp is calculated based on the above, and the final injection pulse width Ti is set by correcting the basic injection pulse width Tp according to operating conditions such as the cooling water temperature Tw. The injection pulse signal of the fuel injection valve 8
Is output at every predetermined injection timing.

Here, the control unit 9 is
The present invention also functions as a control unit (sound wave generation control means) of the vehicle active noise control device according to the present invention. As a constituent element of the vehicle active noise control device, a sound wave is generated in the intake system in the air cleaner 2 part. A speaker 21 is provided as a sound wave generating means for
On the upstream side of the air cleaner 2, a microphone (hereinafter, also referred to as an error microphone) 22 as a cancellation residual sound detecting means for detecting noise (cancellation residual sound) emitted as a result of active noise control is provided.

The control unit 9 uses the air flow meter to reduce intake noise of the engine as automobile noise, particularly noise generated by intake pulsation.
The intake air flow rate detection signal Qa from 10 is processed (gain adjustment and phase adjustment) to generate a drive signal for generating a sound wave that cancels the intake pulsation noise, and the drive signal is output to the speaker 21 to intake air. Generates sound waves to cancel pulsating noise.

Further, the result of the cancellation of the intake noise (cancellation residual sound) is detected by the error microphone 22, and the phase control and the like in the signal processing for generating the drive signal from the intake air flow rate detection signal Qa is corrected. Has become.
A first embodiment of the active noise control will be described according to the flowchart of FIG.

In the first embodiment, as shown in FIG. 4, an intake system internal temperature sensor 23 as an intake system internal temperature detecting means for detecting the temperature in the intake system is provided. Further, in the first embodiment, the functions as the sound wave generation control means and the control characteristic correction means are provided in software by the control unit 9 as shown in the flowchart of FIG.

In the flowchart of FIG. 5, in step 1 (denoted as S1 in the figure; the same applies hereinafter), the temperature Ta in the intake system detected by the temperature sensor 23 in the intake system is read. In step 2, the intake system temperature Ta is changed to
It is converted into a sound wave transmission velocity (sound velocity) v in the intake system.

In step 3, the air flow meter 10
The intake air flow rate detection signal Qa from
The correction value C _G for correcting the gain adjustment for generating the drive signal of is set based on the transmission speed v. Generally, the temperature in the intake system rises and the speaker
When the temperature of 21 rises, the intensity of the sound emitted from the speaker 21 with respect to the drive signal decreases, so it is necessary to increase the correction of the drive signal in response to the increase in the intake system internal temperature to cancel the intake noise. Energy is secured.

In the next step 4, the correction value C _P for correcting the phase adjustment in processing the intake air flow rate detection signal Qa from the air flow meter 10 to generate the drive signal of the speaker 21 is transmitted. Set based on speed v. Generally, when the temperature in the intake system decreases and the temperature of the speaker 21 decreases, the speaker 21 responds to the drive signal.
Since the response of the sound emitted from is deteriorated, the phase of the drive signal is advanced with respect to the change in the temperature inside the intake system, and it is possible to accurately generate the sound wave in the opposite phase to the intake noise. Is.

Here, the gain and the phase can be adjusted by using the detection result of the error microphone 22. In this case, the gain and the phase are gradually changed so that the most effective silencing can be achieved. We will look for possible gain and phase,
In the first embodiment, the gain and phase close to the optimum value can be specified based on the intake system internal temperature Ta, and the control can be optimized with good response to the temperature change in the intake system.

In the flow chart of FIG. 5, the intake system temperature Ta is once converted to the sonic velocity v.
The correction values C _G and C _P may be set directly from a. Next, according to the flowchart of FIG.
An embodiment will be described. Incidentally, in the second embodiment,
It is assumed that the temperature sensor 23 in the intake system is not provided. Further, in the second embodiment, the control unit 9 is provided with the functions of the sound wave generation control means, the specific frequency intensity detection means, and the gain characteristic correction means, as shown in the flowchart of FIG.

In the flowchart of FIG. 6, first, at step 11, the speaker 21 generates a sound wave of a specific frequency for intensity detection that does not interfere with intake noise. Then, in step 12, the intensity S1 of the specific frequency is obtained by frequency analysis of the detection signal of the error microphone 22. In step 13, the intensity S1 obtained in step 12 is multiplied by a predetermined number to improve the S / N ratio.

In step 14, the ratio between the actual detected intensity S1 multiplied by the predetermined number and the reference value S2 of the intensity predicted from the drive signal used to generate the specific frequency is corrected by the gain adjustment. Correction value C _G (C _G = S
1 / S2). That is, the fact that the intensity of the sound wave obtained with respect to the drive signal in the speaker 21 is changed by being affected by environmental conditions such as the temperature in the intake system is determined by the preset drive signal. The intensity is actually detected and detected, the drive signal is corrected by the amount of change in the intensity, and the energy necessary for canceling the intake noise can be generated from the speaker 21.

Next, a third embodiment will be described with reference to the flowchart of FIG. In the third embodiment as well, the intake system internal temperature sensor 23 is not provided as in the second embodiment. In addition, in the third embodiment,
It is assumed that the control unit 9 has the functions of the sound wave generation control means, the response delay time detection means, and the phase control characteristic correction means, as shown in the flow chart of FIG.

In the flowchart of FIG. 7, first, in step 21, a drive signal is output to the speaker 21 to cause the speaker 21 to generate a sound wave of a specific frequency that does not interfere with intake noise. In step 22, the time T2 from the output of the drive signal until the sound wave of the specific frequency is detected by the error microphone is measured (see FIG. 8).

In step 23, the deviation between the reference value T1 of the time and the measured time T2 is set as a correction value C _P (C _P = T2-T1) for correcting the phase adjustment. The reference value T1 is preset as the time until the sound wave of the specific frequency is detected by the error microphone under the reference condition, and the response characteristic of the speaker 21 is influenced by the environmental conditions such as the temperature in the intake system. That it ’s changing
The difference between the times T1 and T2 is detected, and the phase is adjusted by the amount of change in the response characteristic so that the sound wave having the opposite phase to the intake noise can be generated with high accuracy.

[0034]

As described above, according to the first aspect of the present invention, even if the intensity of sound waves generated or the response characteristic changes due to the influence of the temperature in the intake system, the gain corresponding to such characteristic change is obtained. Since at least one of the characteristic and the phase control characteristic can be modified, there is an effect that a desired silencing effect can be maintained.

According to the second aspect of the present invention, even if the intensity change of the sound wave actually obtained with respect to the drive signal changes due to the temperature change in the intake system or the like, the gain can be corrected properly in accordance with the characteristic change. The effect is that the energy necessary for canceling the intake noise can be set with high accuracy by setting.
According to the invention of claim 3, even if intake noise is present,
The correlation between the drive signal and the generated sound wave intensity can be accurately detected,
Therefore, there is an effect that the gain can be set with high accuracy.

According to the invention as set forth in claim 4, there is an effect that it is possible to detect the change in the intensity of the sound wave generation due to the temperature influence in the intake system while detecting the residual noise canceling the intake noise. According to the invention described in claim 5, the phase can be corrected according to the response delay change of the sound wave generation due to the temperature change in the intake system and the like, so that the sound wave having the opposite phase to the intake noise can be accurately generated. There is an effect that it can be generated.

According to the invention described in claim 6, there is an effect that the change in the response delay can be easily detected as the time from the generation of the drive signal to the detection of the sound wave.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the invention according to claim 1;

FIG. 2 is a block diagram showing the configuration of the invention according to claim 2;

FIG. 3 is a block diagram showing the configuration of the invention according to claim 5;

FIG. 4 is a diagram showing a system configuration of an embodiment.

FIG. 5 is a flowchart showing a state of noise control according to the first embodiment.

FIG. 6 is a flowchart showing how noise control is performed in the second embodiment.

FIG. 7 is a flowchart showing a state of noise control according to the third embodiment.

FIG. 8 is a time chart showing how response is detected in the third embodiment.

[Explanation of symbols]

 1 Engine 2 Air Cleaner 3 Intake Duct 4 Throttle Chamber 5 Intake Collector 6 Intake Manifold 7 Throttle Valve 9 Control Unit 10 Air Flow Meter 11 Crank Angle Sensor 21 Speaker 22 Microphone 23 Intake System Temperature Sensor

Claims (6)

[Claims] 1. An active noise control device for an automobile, which generates a sound wave having the same amplitude as the intake noise of an engine but a reverse phase to cancel the intake noise, comprising sound wave generating means for generating a sound wave in an intake system of the engine. An intake noise detecting means for detecting intake noise of the engine, and an intake noise detected by the intake noise detecting means,
A sound wave generation control means for driving and controlling the sound wave generation means to generate a sound wave for canceling the intake noise, an intake system internal temperature detection means for detecting the temperature in the intake system, and an intake system internal temperature detection means. Control characteristic correcting means for correcting at least one of the gain characteristic and the phase control characteristic in the sound wave generation control means based on the temperature in the intake system detected by Active noise control device. 2. An active noise control system for an automobile, which generates a sound wave having the same amplitude as the intake noise of the engine but an opposite phase to cancel the intake noise, and a sound wave generating means for generating the sound wave in an intake system of the engine. An intake noise detecting means for detecting intake noise of the engine, and an intake noise detected by the intake noise detecting means,
A sound wave generation control means for driving and controlling the sound wave generation means to generate a sound wave for canceling the intake noise; a specific frequency intensity detection means for detecting the intensity of a sound wave of a specific frequency generated by the sound wave generation means; An active noise control device for an automobile, comprising: a gain characteristic correction unit that corrects a gain characteristic in the sound wave generation control unit based on a comparison between the intensity detected by the specific frequency intensity detection unit and a reference intensity. 3. The active noise control system for an automobile according to claim 2, wherein the specific frequency is a frequency that does not interfere with intake noise. 4. A cancellation residual sound detecting means for detecting a cancellation residual sound of the intake noise is provided, and the specific frequency intensity detecting means detects the intensity of the specific frequency by frequency analysis of a detection result of the cancellation residual sound detecting means. The active noise control device for an automobile according to claim 2, wherein the active noise control device is detected. 5. An active noise control device for an automobile, which generates a sound wave having the same amplitude as an intake noise of an engine but a phase opposite thereto to cancel the intake noise, the sound wave generating means generating a sound wave in an intake system of the engine. An intake noise detecting means for detecting intake noise of the engine, and an intake noise detected by the intake noise detecting means,
A sound wave generation control means for driving and controlling the sound wave generation means to generate a sound wave for canceling the intake noise, a response delay time detection means for detecting a response delay time of the sound wave generation means, and the response delay time detection means An active noise control device for an automobile, comprising: a phase control characteristic correction unit that corrects the phase control characteristic in the sound wave generation control unit based on a comparison between the response delay time detected in (1) and the reference delay time. 6. A cancellation residual sound detecting means for detecting a cancellation residual sound of the intake noise, wherein the response delay time detecting means detects a sound wave generated by the sound wave generating means by the cancellation residual sound detecting means. The vehicle active noise control device according to claim 5, wherein a response delay time is detected as a time until the noise occurs.