JPH06266371A - Active noise controller for vehicle - Google Patents

Abstract

PURPOSE:To reduce an in-cabin noise in the low-speed rotation range of an engine by fitting an exciting machine to a vehicle body panel and actively controlling vehicle body panel vibration of low frequency. CONSTITUTION:A sine wave having the secondary period of engine rotation is generated in a processor 401 on the basis of the engine rotation signal generated by an engine control unit 3. The phase and amplitude of the sine wave are adjusted by an adaptive filter 402. At this time, the switching of a changeover switch 403 which selects the exciting machine 6 or a speaker 7 for output is controlled according to the value of the engine rotational frequency calculated from the engine rotation signal. The digital signal whose phase and amplitude are controlled by the adaptive filter 402 after being selected by an output changeover switch 403 is converted through a D/A converter into an analog signal and an amplifier or driving circuit generates the driving signal of the exciting machine 6 or speaker 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reduction device for actively canceling noise in the vehicle interior generated by the operation of a vehicle engine by vibration or sound having an antiphase calculated from the frequency of engine vibration. Regarding

[0002]

2. Description of the Related Art Among the vibration noises of a vehicle, a vehicle engine has a large weight.
In the case of cylinders, vibrations that occur twice per rotation (hereinafter referred to as secondary rotation) that occur due to explosion in each cylinder can be mentioned. This rotational secondary vibration vibrates the panel of the vehicle body, and as a result, the volume in the vehicle compartment changes periodically, resulting in a "muffled sound" that presses the ears of the occupant and increases noise in the vehicle interior. It makes passengers feel uncomfortable.

A conventional solution to this problem is, for example, the technique disclosed in FIG. 7 of British Patent No. 2149614. That is, a plurality of loudspeakers (hereinafter referred to as speakers) arranged in a closed space (vehicle interior), a microphone (hereinafter referred to as a microphone) for measuring sound pressure at a predetermined position in the room, and an acoustic measurement means for measuring a frequency of a reference input. And a least mean square algorithm (hereinafter referred to as LMS algorithm) which is a kind of steepest descent method so as to receive the input signals from the microphone and the sound source frequency means and minimize the sound pressure level in the closed space.
Is an active noise attenuating device including a signal processor set to output a noise signal from each speaker.

This method is extremely effective because the secondary frequency of rotation becomes relatively high when the engine is rotating at high speed, and the speaker can generate a canceling sound of a sufficient volume and the same frequency. there were. However, when the engine is rotating at a low speed, the secondary frequency of rotation becomes low, so that it is impossible to generate a canceling sound having the same frequency as the low-frequency sound reproduction limit of the speaker, and a sufficient reduction effect cannot be obtained. There was a flaw.

On the other hand, as a means for solving the above-mentioned problems, there is a method of lowering the bass reproduction limit by using a large speaker suitable for bass reproduction, but there is a restriction in using it in a limited vehicle space. In many cases, it was difficult to call it a realistic method.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a noise control device capable of sufficiently reducing "combustion noise" such as vehicle interior noise caused by secondary engine rotation vibration even when the engine is rotating at low speed. To provide without sacrificing vehicle space.

[0007]

SUMMARY OF THE INVENTION The above object is to control a vibration exciter for canceling a vibration generated in a panel of a vehicle body, a signal source for supplying a drive signal to the vibration exciter, and a phase and an amplitude of a noise signal. Control means, a detecting means for detecting the residual noise in the vehicle compartment after the vibration of the vehicle body panel is canceled by the output of the vibration exciter, a speaker for canceling the noise in the vehicle compartment, and a drive signal are supplied to the speaker. In a device provided with a signal source, a control means for controlling the phase and amplitude of an audio signal, and a detection means for detecting a residual noise in a vehicle compartment after the noise is canceled by a speaker output, an engine rotation secondary frequency is a speaker frequency. During low-speed rotation below the bass reproduction limit, the adaptive filter provided in the control means adaptively controls the phase and amplitude of the vibrator drive signal to minimize the residual noise in the vehicle interior, while rotating the engine. At the time of high-speed rotation when the next frequency reaches the bass reproduction limit of the speaker, the phase and amplitude of the speaker drive signal are adaptively controlled by the adaptive filter provided in the control means so that the residual noise in the vehicle compartment is minimized. Achieved by

[0008]

By attaching the vibration exciter to the vehicle body panel that serves as a transmission path of the rotational vibration of the engine, it is possible to actively reduce the low frequency body panel vibration. As a result, in the conventional speaker, it is possible to reduce the vehicle interior noise in the low speed rotation range of the engine, where the sufficient sound deadening effect could not be obtained due to the bass reproduction limit. On the other hand, when the engine is rotating at high speed, it is difficult to vibrate it at a high frequency due to the size of the vehicle body panel. Can be reduced. Therefore, it is possible to obtain a sufficient silencing effect under all conditions from low speed rotation to high speed rotation of the engine.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an automobile will be described with reference to FIGS.

FIG. 2 shows the structure of an active noise control system for an automobile to which the present invention is applied. An engine 2 is mounted on the vehicle body 1 via a rubber mount or the like. The engine rotation signal generated by the engine control unit 3 is input to the noise control unit (hereinafter control unit) 4. In addition, the body panel (door panel in this case) 5
A shaker 6 is attached to the control unit 4, and the phase and amplitude of the drive signal of the shaker are controlled by the control unit 4.

On the other hand, as shown in FIG. 4, a speaker 7 having a bass limit frequency of fc is mounted in the passenger compartment, and like the vibrator 6, the phase and amplitude of the drive signal are controlled by the control unit 4. It Further, a microphone 8 is attached near the occupants' ears in the passenger compartment, and its output is taken into the control unit 4 and used to control the drive signals of the above-mentioned vibrator 6 and speaker 7.

Next, the hardware configuration of the control unit 4 will be described with reference to FIG. Based on the engine rotation signal generated by the engine control unit 3, the processor
In 401, a sine wave having a second cycle of engine rotation is created. The phase and amplitude of this sine wave are adjusted by the adaptive filter 402. At this time, the switching of the output changeover switch 403 that selects the vibrator 6 or the speaker 7 as an output is controlled by the magnitude of the engine speed Ne calculated by the engine speed signal. As a condition for this switching, if the engine rotation secondary frequency, that is, Ne × 2/60 is larger than the bass limit frequency fc of the speaker, the canceling sound with sufficient sound pressure can be output from the speaker 7. , The speaker 7 is selected as the output.

On the other hand, when Ne × 2/60 is smaller than fc, it becomes difficult to output the canceling sound having a sufficient sound pressure from the speaker 7, so that the vibration exciter mounted on the vehicle body panel 5 as an output. Select 6. Expressing the above switching by a mathematical expression, when Ne ≧ 30 · fc, the speaker installed in the vehicle compartment is driven, and when Ne <30 · fc, the vibration exciter attached to the vehicle body panel is driven.

The digital signal whose phase and amplitude are controlled by the adaptive filter 402 is passed through the D / A converter after the vibrator 6 or the speaker 7 is selected as an actuator by the output changeover switch 403, and then the analog signal is passed. After being converted into a signal, the amplifier or the drive circuit becomes a drive signal for the vibrator 6 or the speaker 7, respectively, and drives the load.

Next, the operation of this embodiment will be described with reference to FIG. When the state of Ne <30 · fc is confirmed by the engine rotation signal, the control unit 4 controls the output of the vibration exciter. In this case, the output changeover switch 403 shown in FIG. 3 is on the V side. The sine wave W ₀ generated based on the rotation signal has its phase and amplitude adjusted by the adaptive filter in the control unit to become the signal Wc. After that, the exciter generates a vibration output Wcp by the D / A converter and the drive circuit, and cancels the vibration Vp of the vehicle body panel generated by the secondary rotation vibration of the engine. The residual noise Sr generated in the vehicle interior due to the residual vibration Vr of the vehicle body panel after the cancellation is detected by the microphone 8 mounted in the vehicle interior and fed back to the control unit 4. On this occasion,
The phase and amplitude of the drive signal Wc are sequentially updated by the adaptive filter so that the magnitude of residual noise detected by the microphone is minimized.

On the other hand, when the condition of Ne ≧ 30 · fc is confirmed by the engine rotation signal, the control unit 4 controls the speaker. In this case, the output changeover switch 403 shown in FIG. 3 is on the S side. The sine wave W ₀ generated based on the rotation signal has its phase and amplitude adjusted by the adaptive filter in the control unit to become the signal Wc. After that, the speaker outputs Wc by D / A converter and amplifier.
i, which cancels the "muffled sound" Si in the vehicle interior caused by the secondary amplitude of rotation of the engine, but the residual noise Sr in the vehicle interior after the cancellation is detected by the microphone 8 mounted in the vehicle interior. And is fed back to the control unit 4. At this time, the phase and amplitude of the drive signal Wc are sequentially updated by the adaptive filter so that the magnitude of the residual noise detected by the microphone is minimized.

As described in detail above, according to this embodiment,
By canceling the vibration of the vehicle body panel in the low-speed rotation range (Ne <30 · fc) of the engine, where the speaker cannot sufficiently suppress the sound due to the bass reproduction limit, it is possible to reduce the vehicle interior noise. As a result, the "crowded noise" can be reduced and the occupant's comfort can be maintained in all engine rotation ranges.

[0018]

According to the present invention, a vibrating machine is attached to a vehicle body panel, which serves as a transmission path of rotational vibration of an engine, and low-frequency vehicle body panel vibration is actively controlled, so that a low-pitched sound is reproduced by a conventional speaker. It is possible to reduce the vehicle interior noise in the low speed rotation range of the engine, where the sufficient noise reduction effect was not obtained at the limit. On the other hand, when the engine is rotating at high speed, it is difficult to vibrate it at a high frequency due to the size of the vehicle body panel. Can be reduced. Therefore, it is possible to obtain a sufficient silencing effect under a wide range of conditions from low speed rotation to high speed rotation of the engine.

[Brief description of drawings]

FIG. 1 is a flowchart showing a basic operation when the present invention is applied to an automobile.

FIG. 2 is an overall configuration diagram in which the present invention is applied to an automobile.

FIG. 3 is a configuration diagram of control hardware in which the present invention is applied to an automobile.

FIG. 4 is a diagram showing frequency characteristics of speaker sound pressure.

[Explanation of symbols]

1 ... vehicle body, 2 ... engine (engine), 4 ... control unit,
5 ... Body panel (door), 6 ... Exciter, 7 ... Speaker, 8
... microphone, 401 ... processor, 402 ... adaptive filter, 403 ... output changeover switch.

Claims (8)

[Claims] 1. A vibration exciter for canceling a vibration generated in a panel portion of a vehicle body by an engine operation of a vehicle, a signal source for supplying a drive signal to the vibration exciter, and a phase and an amplitude of the drive signal. In a device having control means for controlling, using an adaptive filter provided in the control means, the phase and amplitude of the drive signal is adaptively controlled according to the operating state of the engine, Vehicle active noise control system. 2. The active noise control system for a vehicle according to claim 1, wherein after the vibration is canceled by the vibration exciter, the magnitude of the vehicle interior residual noise defined by the defined evaluation function becomes substantially minimum. Thus, the active noise control device for a vehicle, which adaptively controls the phase and amplitude of the drive signal. 3. The active noise control system for a vehicle according to claim 2, wherein a microphone is used for detecting the magnitude of the residual noise in the vehicle interior. 4. A vehicle having a speaker for canceling noise in the passenger compartment, a signal source for supplying a drive signal to the speaker, and control means for controlling the phase and amplitude of the drive signal. An active control device for vehicle interior noise is provided, which adaptively controls the phase and amplitude of the drive signal according to the noise state in the vehicle interior by using an adaptive filter provided in the means. An active noise control device for a vehicle, comprising: the active noise control device for a vehicle according to claim 1. 5. The active noise control device for a vehicle according to claim 4, wherein only one of the speaker drive signal and the vibration exciter drive signal is controlled according to the driving state of the vehicle. 6. The method according to claim 5, wherein when the engine speed of the passenger compartment is equal to or lower than a predetermined engine speed, only the exciter drive signal is controlled, and the speaker drive signal is operated when the engine is not in the above condition. An active noise control device for a vehicle, which controls only the vehicle. 7. A vehicle equipped with an in-line four-cylinder engine having the noise control device according to claim 6, wherein when the engine speed Ne is equal to or lower than a critical speed Nc represented by the following equation, a shaker drive signal is output. An active noise control device for a vehicle, which controls only a speaker drive signal when Ne is Nc or more. Nc = 30 · fc Here, fc is the lowest frequency (bass limit frequency) at which the speaker can exhibit a predetermined characteristic. 8. The active vibration noise control device for a vehicle according to claim 5, wherein the adaptive filter for controlling the phase and the amplitude of the speaker drive signal or the exciter drive signal is common.