JPH0921365A - Active noise control system for automobile - Google Patents

Abstract

(57) Abstract: A noise reduction effect is continuously obtained even if a microphone that detects intake noise fails. SOLUTION: When a microphone that detects intake noise fails, the frequency of the intake sound is estimated based on the engine rotation speed Ne (S32), and further, the engine rotation speed Ne.
And the amplitude of the intake sound is estimated based on the throttle valve opening TVO (S33). Then, while the sound wave of the estimated frequency and amplitude is generated from the speaker provided in the air cleaner section (S34), the phase of the sound wave generated from the speaker is fed back based on the detection result of the microphone that detects the cancellation residual sound. Control (S35).

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 system for a vehicle, which actively reduces noise in a vehicle by interference of separately generated sound waves, and more particularly to a technique for reducing intake system 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 system noise generated by the intake pulsation of the engine by the active noise control, a speaker is installed in the intake system which is the noise source and the intake system noise (pulsation is Noise) is detected by a microphone or the like, and a sound wave that cancels the detected noise is generated from the speaker, whereby intake noise can be positively reduced.

[0004]

By the way, in the active noise control, it is necessary to detect noise (intake sound) with high precision in order to effectively cancel the noise, and to detect intake noise of a microphone or the like. If a failure (including deterioration) occurs in the means to operate and the detection signal does not correspond to the actual intake noise correctly, the desired sound deadening effect will not be obtained, or the secondary noise will generate noise. There is a fear of making it worse.

Therefore, when failure (including deterioration) occurs in the means for detecting intake noise such as a microphone,
It is preferable to stop the use, but if the noise canceling control is stopped due to a failure of the microphone or the like, there is a problem that the silencing effect cannot be obtained at all. The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to continuously obtain a silencing effect while avoiding deterioration of noise due to a failure of means for detecting intake noise. To do.

[0006]

Therefore, an active noise control system for an automobile according to the invention of claim 1 is constructed as shown in FIG. In FIG. 1, the intake sound detecting means is inserted in the intake system of the engine and outputs a detection signal corresponding to the intake sound. Further, the sound wave generating means generates a sound wave in the intake system of the engine.

The intake noise canceling means drives the sound wave generating means so as to generate a sound wave that cancels the intake sound based on the detection signal from the intake sound detecting means.
Further, the cancellation residual sound detecting means detects the cancellation residual sound by the intake noise canceling means, and the feedback control means controls the drive of the sound wave generating means by the intake noise canceling means based on the detection result of the cancellation residual sound detecting means. To fix.

On the other hand, the failure diagnosis means diagnoses whether or not there is a failure in the intake noise detection means, and the fail safe control means
When a failure of the intake sound detecting means is diagnosed by the failure diagnosing means, the intake sound is estimated based on the operating condition of the engine, and the drive control of the sound wave generating means by the intake noise canceling means is performed based on the estimation result. To perform. According to such a configuration, a sound wave for canceling the intake noise is separately generated in the intake system based on the detection result of the intake noise to cancel the intake noise. Further, by detecting the sound left by the cancellation (remaining cancellation sound) and correcting the sound wave to be generated, the cancellation effect is maximized.

Here, if the intake sound detecting means fails, there is a risk of generating an erroneous secondary sound that does not correspond to the actual intake sound. Therefore, the secondary sound is generated using the detection signal of the intake sound detecting means. Then, the intake noise is estimated from the operating condition of the engine, and a secondary sound is generated based on the estimation result to cancel the intake noise. Claim 2
In the active noise control device for a vehicle according to the invention,
The engine operating condition in the fail-safe control means is configured to include at least one of the throttle valve opening and the engine rotation speed.

According to this structure, at least one of the throttle valve opening and the engine speed is used as the engine operating condition, and the sound pressure and frequency of the intake sound are estimated based on these parameters. In the vehicle active noise control system according to the invention of claim 3, the fail-safe control means estimates the sound pressure of the intake sound based on at least the throttle valve opening.

According to this structure, the sound pressure of the intake sound is estimated based on at least the throttle valve opening, and the sound wave having the amplitude corresponding to the estimated sound pressure is generated. In the vehicle active noise control system according to the invention of claim 4, the fail-safe control means estimates the frequency of the intake noise based on the rotation speed of the engine.

According to such a configuration, the frequency of the intake sound is estimated based on the rotation speed of the engine, and the sound wave having the estimated frequency is generated. In the automobile active noise control device according to the invention of claim 5, there is no failure in the residual sound detection diagnostic means for diagnosing whether or not there is a failure in the cancellation residual sound detection means, and in the intake sound detection means by the failure diagnosis means. Is diagnosed, and the residual sound detecting means diagnoses a malfunction of the canceling residual sound detecting means, the correction control by the feedback control means is stopped, and the sound wave generating means is performed only by the intake noise canceling means. And an open control means for driving and controlling.

According to this structure, although the intake sound detecting means is normal, when the canceling residual sound detecting means fails, the feedback control based on the detection result of the canceling residual sound is stopped, but the intake sound detecting means The sound wave generation control based on the detection signal from the means is continued as it is, and the intake noise is reduced by the feed-forward control.

[0014]

Embodiments of the present invention will be described below. FIG. 2 shows the system configuration of the embodiment. The engine 1 includes an air cleaner 2, an intake duct 3,
Air is taken in through the throttle chamber 4, the intake collector 5, and the 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 intake air amount of the engine 1. An electromagnetic fuel injection valve 8 is provided for each cylinder in a branch portion of the intake manifold 6, and fuel injected from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator is injected into the intake manifold 6. Supply.

The fuel injection valve 8 is intermittently driven to open according to an injection pulse signal sent from a control unit 9 having a built-in microcomputer, and according to the 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 amount Qa of the engine 1. Here, the air flow meter 10 detects 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.

A crank angle sensor 11 for extracting a rotation signal of the engine 1 from a crank shaft or a cam shaft is provided, and the engine rotation is performed based on a detection signal output from the crank angle sensor 11 at every predetermined crank angle. Speed Ne
Can be calculated. Further, a throttle sensor 12 for detecting the opening TVO of the throttle valve 7, a water temperature sensor 13 for detecting the engine cooling water temperature Tw, etc. are provided.

The control unit 9 calculates the basic injection pulse width Tp based on the intake air amount Qa detected by the air flow meter 10 and the engine speed Ne calculated based on the detection signal from the crank angle sensor 11. At the same time, the basic injection pulse width Tp is set to the cooling water temperature Tw.
The final injection pulse width T is corrected according to operating conditions such as
i is set, and an injection pulse signal having the injection pulse width Ti is output to the fuel injection valve 8 at every predetermined injection timing.

Here, the control unit 9 is
The air cleaner 2 functions also as a control unit of the active noise control device for a vehicle according to the present invention, and serves as a constituent element of the active noise control device for a vehicle.
A speaker 21 (sound wave generating means) for generating a sound wave in the intake system is provided in the section, and the sound in the intake system (intake system noise) is electrically supplied to the intake duct 3 between the throttle chamber 4 and the air flow meter 10. Microphone to convert to signal
22 (intake sound detection means) is provided. Further, on the upstream side of the air cleaner 2, there is provided a microphone 23 (cancellation residual sound detecting means) for detecting noise (cancellation residual sound) emitted as a result of noise cancellation by the speaker 21.

In order to reduce the intake system noise of the engine as automobile noise, the intake system noise (mainly intake pulsation noise) is detected based on the detection signal from the microphone 22, and the intake system noise (primary sound) is detected. ) And a sound wave (secondary sound) that cancels out the noise is provided in the intake system.
A drive signal is output to the speaker 21 so as to be separately generated from the 21 (intake noise canceling means).

The flow chart of FIG. 3 shows a state of the noise reduction control. In this embodiment,
As shown in the flowchart of FIG. 3, the control unit 9 has software functions of the intake noise canceling means and the feedback control means.
In the flowchart of FIG. 3, first, in step 1 (denoted as S1 in the figure; the same applies hereinafter), the detection signal of the microphone 22 is A / D converted and read, and in step 2, whether or not it is within the sampling window is checked. Determine.

Then, in the sampling window, in order to obtain the power spectrum PS1 in a predetermined frequency range, the output of the microphone 22 is sequentially processed as data MKn (n = 1, 2, 3, ...) In step 3. When the data is stored and exceeds the sampling window, all the storage data MKn are reset in step 4. On the other hand, the data M obtained within the sampling window
Based on Kn, in step 5, a component in a predetermined frequency range is extracted by Fourier transform or the like, and the extraction result is set as a power spectrum PS1. Here, the predetermined frequency range is
It is made to correspond to the frequency range of the intake pulsation, and the same frequency range is also extracted in the power spectrum PS2 of the output of the microphone 23 described later.

In the next step 6, phase control is applied to the extracted frequency component PS1 to give a phase rotation of a predetermined angle θ for canceling the intake sound. The phase difference of the predetermined attitude θ is such that when the intake pulsation noise reaches the speaker 21, the intake pulsation noise and the phase of the sound wave generated from the speaker 21 are 180 ° out of phase (opposite phase). , Set.

Then, in step 7, a drive signal corresponding to the frequency component PS1 subjected to the phase control is output to the speaker 21, and a sound wave having the same amplitude and the same frequency as the intake noise but an opposite phase is generated by the speaker 21. The noise of the intake air is canceled by the interference between the noise of the intake air and the sound wave generated from the speaker 21. In steps 8 to 12, the output processing of the microphone 22 (steps 1 to 1)
In the same manner as 5), the output of the microphone 23 for detecting the cancellation residual sound is processed to obtain the power spectrum PS2 having the same frequency component as the power spectrum PS1 for the output of the microphone 23.

At step 13, whether or not the power spectrum PS2 of the microphone 23 is the minimum, in other words,
It is determined whether or not the cancellation residual sound resulting from the reduction of the sound pressure by the sound wave generated by the speaker 21 is the minimum. When it is determined in step 13 that the power spectrum PSQ2 is not the minimum, the process proceeds to step 14. , The predetermined angle θ used for the phase control in the step 6 is corrected and set by a predetermined value Δθ, and the process of shifting the phase of the sound wave generated from the speaker 21 is performed to give the phase difference that minimizes the power spectrum PS2. To do so.

That is, since the sound picked up by the microphone 23 is a canceling residual sound, the phase difference is corrected so that the sound pressure of this residual sound is minimized, and even if there are various variations,
It is intended to effectively cancel noise.
Therefore, instead of the phase difference or together with the phase difference, the amplitude of the sound wave generated from the speaker 21 may be adjusted.

The flow chart of FIG. 4 shows the fail safe control in the active noise control system described above. In the present embodiment, the functions of the failure diagnosing means, the fail-safe control means, the residual sound detecting and diagnosing means, and the open control means are provided in software by the control unit 9 as shown in the flowchart of FIG. .

Steps in the flowchart of FIG.
At 21, it is determined whether or not a failure has occurred in the speaker 21. Such failure diagnosis is performed by, for example, electrical diagnosis such as disconnection in the output line of the speaker drive signal. Further, the predetermined sound generated from the speaker 21 may be detected by the microphones 22 and 23, and the failure diagnosis may be performed depending on whether or not a desired sound wave is actually generated.

Similarly, in step 22, a failure of the amplifier forming the speaker drive circuit is electrically diagnosed. Here, when the failure of the speaker 21 or the failure of the amplifier is diagnosed, the process proceeds to step 23 to stop the active noise control by driving the speaker 21. This is because even if the intake noise can be detected with high accuracy, it is not possible to generate a sound wave commensurate with the detected intake noise.

On the other hand, when it is diagnosed that both the speaker 21 and the amplifier are normal, the routine proceeds to step 24, where it is diagnosed whether or not the microphone 22 as the intake sound detecting means is out of order. Such a failure of the microphone 22 is predicted from electrical detection such as disconnection detection, sound generated from the speaker 21, or throttle valve opening (engine load representative value), rotational speed, etc. as described later. It can be performed based on whether or not the detection signal corresponding to the engine intake sound is output.

When the microphone 22 is normal,
Further, the process proceeds to step 25, and the failure diagnosis of the microphone 23 is performed. Here, if the microphone 23 is also normal, the process proceeds to step 26, and normally, the drive control of the speaker 21 based on the detection result of the microphone 22 is feedback-corrected based on the detection result of the microphone 23 to reduce intake noise. Try to cancel.

On the other hand, if the microphone 23 is out of order, the feedback noise cannot be corrected, but the intake noise can be detected by the microphone 22, so the process proceeds to step 27 and only the detection result of the microphone 22 is detected. Based on this, the control is shifted to the open control state in which feed forward control is performed. When the failure of the microphone 22 is diagnosed in step 24, the process proceeds to step 28 to diagnose the failure of the microphone 23.

If the microphone 23 is normal even if the microphone 22 is out of order, the process proceeds to step 29, where the speaker is used without using the detection signal of the microphone 22.
Drive 21 to cancel intake noise. That is, the main cause of the intake noise is the intake pulsation, and the amplitude of the intake pulsation is based on the throttle valve opening TVO representing the engine load or the combination of the throttle valve opening TVO and the engine rotation speed Ne. While being estimated, its frequency can be estimated based on the engine speed Ne.

Therefore, the amplitude and frequency of the intake noise are estimated based on the throttle valve opening TVO and the engine speed Ne, and the speaker 21 is driven based on the estimation result, while the phase based on the detection result of the microphone 23 is detected. The correction feedback control is continued to optimally set the phase unknown from the engine operating conditions. The state of the fail-safe control when the microphone 22 fails is shown in the flowchart of FIG.

In the flowchart of FIG. 5, at step 31, the throttle valve opening TVO and the engine speed Ne are read. In step 32, the frequency of the intake noise is estimated based on the read engine rotation speed Ne. In the next step 33, the amplitude (sound pressure) of intake noise is estimated based on the engine speed Ne and the throttle valve opening TVO.

Then, in step 34, a sine wave having the estimated amplitude and frequency is generated and output to the speaker 21 as a drive signal. In step 35, based on the detection result of the microphone 23, the phase of the sound wave generated from the speaker 21 is corrected so that the cancellation residual sound is minimized. By such feedback control of phase correction, even if the phase of the intake noise is unknown from the engine operating conditions, it is possible to generate a sound wave that cancels the intake noise.

With the above arrangement, even if the microphone
Even if 22 fails, it is possible to maintain the sound deadening effect by the sound wave generated from the speaker 21. On the other hand, when it is diagnosed in step 28 of the flowchart of FIG. 4 that the microphone 23 is out of order, the phase cannot be corrected and there is a possibility that the sound wave generated from the speaker 21 may worsen the noise. Go to 30 Speaker 21
To stop the active noise control.

In the present embodiment, the microphone 22 is used as the intake sound detecting means, but since the intake air pulsation, which is the main cause of intake system noise, is detected by the air flow meter 10, the intake air flow meter 10 It may be configured to be used as the sound detecting means.

[0039]

As described above, according to the vehicle active noise control system of the invention of claim 1, when the intake noise detecting means fails, the intake noise is estimated from the operating condition of the engine, and the estimation result is obtained. Since the secondary sound is generated based on the above, there is an effect that the intake noise reduction effect can be continuously obtained.

According to the vehicle active noise control system of the invention, the sound pressure and frequency of the intake sound are estimated based on at least one of the throttle valve opening and the engine speed to cancel the intake sound. There is an effect that a sound wave can be generated. According to the vehicle active noise control device of the third aspect of the present invention, the sound pressure of the intake sound is estimated based on at least the throttle valve opening to generate a sound wave having an amplitude corresponding to the sound pressure of the intake sound. There is an effect that can be.

According to the vehicle active noise control system of the invention of claim 4, the frequency of the intake sound is estimated based on the rotation speed of the engine to generate the sound wave having the frequency corresponding to the frequency of the intake sound. There is an effect that can be. According to the active noise control device for an automobile of the fifth aspect of the present invention, when the cancellation residual sound cannot be detected, the feed noise control can reduce the intake noise.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of an active noise control system for a vehicle according to the present invention.

FIG. 2 is a diagram showing a system configuration of the embodiment.

FIG. 3 is a flowchart showing active noise control according to the embodiment.

FIG. 4 is a flowchart showing how failsafe control is performed in the embodiment.

FIG. 5 is a flowchart showing a state of estimation control of intake sound based on operating conditions in the 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 12 Throttle Sensor 21 Speaker 22, 23 Microphone

Claims (5)

[Claims] 1. An intake sound detecting means which is interposed in an intake system of an engine and outputs a detection signal corresponding to intake sound; a sound wave generating means which generates a sound wave in the intake system of the engine; and the intake sound detecting means. Intake noise canceling means for driving the sound wave generating means so as to generate a sound wave for canceling the intake sound based on the detection signal from Feedback control means for correcting drive control of the sound wave generating means by the intake noise canceling means based on the detection result of the residual sound detecting means, failure diagnosing means for diagnosing presence / absence of failure of the intake sound detecting means, and the failure. When the diagnostic means diagnoses a failure of the intake sound detecting means, the intake sound is estimated based on the operating condition of the engine, and based on the estimation result. Serial intake noise cancellation means by said wave and fail-safe control means for causing the drive control of the generating means, the comprise configuration and active noise control system for a motor vehicle. 2. The operating condition of the engine in the fail-safe control means includes at least one of a throttle valve opening and an engine rotation speed.
An active noise control device for a vehicle as described above. 3. The active noise control system for an automobile according to claim 2, wherein the fail-safe control means estimates the sound pressure of the intake sound based on at least the throttle valve opening. 4. The active noise control system for a vehicle according to claim 2, wherein the fail-safe control means estimates the frequency of the intake noise based on the rotation speed of the engine. 5. A residual sound detecting and diagnosing means for diagnosing whether or not there is a failure in the cancellation residual sound detecting means, and the failure diagnosing means for diagnosing that there is no failure in the intake sound detecting means, and the residual sound detection. An open control means for stopping the correction control by the feedback control means and drivingly controlling the sound wave generation means only by the intake noise cancellation means when a failure of the cancellation residual sound detection means is diagnosed by means. The vehicle active noise control device according to claim 1, wherein the active noise control device is provided.