JPH05297878A - Reducing device for indistinct sound in cabin - Google Patents

Abstract

PURPOSE:To obtain the in-cabin indistinct sound reducing device which has superior follow-up performance and stability. CONSTITUTION:The signals from an air suction amount sensor 5 and a crank angle sensor 7 are inputted to a signal converting circuit 9 and a memory map setting circuit 10; and the memory map setting circuit 10 selects and sets the filter coefficient W(n) of an adaptive filter 11 by map retrieval based upon engine load information and engine rotation information and the signal converting circuit 9 shapes and processes a primary source and outputs it to an LMS arithmetic circuit 13 through the adaptive filter 11 and a CMN0 circuit 12. The primary source is mixed by the adaptive filter 11 with a canceling signal and outputted as a canceling sound from a speaker 16, and the state at a listening point is detected as an error signal by an error microphone 17 and sent to the LMS arithmetic circuit 13 to update the filter coefficient W(N) of the adaptive filter 11 so that the error signal becomes minimum. This updated filter coefficient W(N) is stored as a new set value of the memory l map setting circuit 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle interior muffler noise reducing apparatus for reducing the muffler noise in the vehicle interior, which is mainly caused by engine vibration noise, by interfering with the canceling noise.

[0002]

2. Description of the Related Art In addition to vehicle interior noise that is mainly caused by engine vibration noise, a sound (cancellation sound) having the same amplitude and opposite phase to this noise is produced from an additional sound source to reduce vehicle interior noise. The technology of is proposed.

As such a technique, for example, Japanese Unexamined Patent Publication No.
No. 5255, numerical data of a basic sine wave, which has an opposite phase in synchronization with a secondary component of engine rotation, is stored in advance, and the engine speed obtained from a crank angle sensor and the engine obtained from a pressure sensor are stored. By modifying the phase and amplitude of the basic sine wave with a load, there is disclosed a vehicle interior noise reduction device capable of producing a canceling sound without requiring a vibration sensor or the like for directly detecting engine vibration or the like.

[0004]

By the way, recent LS
By the I technique, LMS (Least Mean Square) algorithm (In order to simplify the calculation formula for obtaining the optimum filter coefficient, the fact that the modified formula of the filter is recursive formula is used, the mean square error is approximated by the instantaneous square error. Or the MEFX-LMS (Multiple Error F), which is an extension of this LMS algorithm to multiple channels.
Illuminated X-LMS) vehicle interior noise reduction devices have begun to be put to practical use. In the vehicle interior noise reduction device using this LMS algorithm, when the vehicle interior noise generated mainly due to engine vibration is silenced,
A signal highly correlated with engine vibration is detected as a noise vibration source signal (primary source) by a vibration sensor, etc., and a canceling sound signal (canceling signal) for noise is synthesized by an optimum filter from this primary source, and a canceling sound is generated from the speaker. To do. Then, the noise reduction state at the listening point is detected as an error signal by the error microphone, and the filter coefficient of the optimum filter is updated from this error signal and the primary source by the LMS algorithm to make the noise reduction at the listening point an optimum value. It is like this. According to the noise reduction device using this LMS algorithm, it is possible to achieve more stable and fine noise reduction than the vehicle interior noise reduction device shown in the related art.

However, since the optimum filter is used, it is necessary to have a large number of filter coefficient matrices, and it takes time to update this filter coefficient, so that it is effective in a transient state such as during rapid acceleration. It is difficult to reduce noise. In addition, if the correction sensitivity of the filter coefficient is increased in order to solve the above-mentioned problem of the followability, the system for updating the filter coefficient by the LMS algorithm easily diverges. Solving sexual problems is difficult.

The present invention has been made in view of the above circumstances, and is a muffled noise in the vehicle interior that can perform noise reduction excellent in followability and stability not only during steady running but also during transient operation. The purpose is to provide a reduction device.

[0007]

In order to achieve the above object, a vehicle interior muffled noise reducing apparatus according to the present invention detects engine load information and rotation information, and detects the frequency spectrum of a predetermined high-order component. A signal converting means for converting as a noise vibration source signal, a cancel signal synthesizing means for synthesizing the noise vibration source signal as a cancel signal by an adaptive filter, and a canceling sound generating means for generating the cancel signal as a canceling sound for noise from a sound source. Error signal detecting means for detecting a noise reduction state at the listening point as an error signal, cancel signal updating means for updating the filter coefficient of the adaptive filter based on the error signal and the noise vibration source signal, and the load of the engine From the information and rotation information, set the filter coefficient of the adaptive filter to a preset value. With the new to, the set value is obtained by a filter coefficient storage setting means for storing modified values updated in the cancellation signal updating means.

[0008]

[Operation] In the above configuration, first, the load information and the rotation information of the engine are detected and converted into a noise vibration source signal having a frequency spectrum composed of a predetermined high-order component determined in advance by the signal conversion means. Further, the filter coefficient storage setting means updates the filter coefficient of the adaptive filter of the cancel signal synthesizing means to a preset value from the load information and the rotation information of the engine. Next, the canceling signal synthesizing means synthesizes the noise vibration source signal as a canceling signal by the adaptive filter, and the canceling sound generating means generates the canceling signal from the sound source as a canceling sound for noise. Next, the noise reduction state at the listening point
The error signal detecting means detects the error signal, and the cancel signal updating means updates the filter coefficient of the adaptive filter based on the error signal and the noise and vibration source signal. Then, the filter coefficient of the adaptive filter updated by the cancel signal updating means is stored and corrected as a new set value in the filter coefficient storage setting means. In this way, by setting the filter coefficient of the adaptive filter according to the operating state of the engine in advance by the filter coefficient storage setting means, it is possible to reduce the processing such as calculation in the cancel signal updating means, so that the followability and stability are improved. Excellent noise reduction can be performed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. {First Embodiment} The drawings show the first embodiment of the present invention, and FIG.
2 is a schematic view of the system of the muffler noise reduction device in the vehicle compartment, FIG. 2 is an explanatory view of the correlation between the primary source and the vibration noise, (a) is the molded and processed primary source, (b) is the vibration noise related to the engine, ( c) is a primary source viewed from the frequency domain, (d) is engine-related vibration noise viewed from the frequency domain, and FIG. 3 is an explanatory diagram of a filter coefficient map.

In the figure, reference numeral 1 indicates a four-cycle engine, an air cleaner 4 is provided upstream of an intake manifold 2 via an intake pipe 3, and immediately below the air cleaner 4, engine load information is provided. An intake air amount sensor 5 for detecting the Also, this engine 1
A crank angle detecting rotor 6 is rotatably mounted on the crank shaft 1a of the above, and engine rotation information such as an electromagnetic pickup for detecting a protrusion, which is a detected object, is detected on the outer periphery of the crank angle detecting rotor 6. The crank angle sensor 7 is installed oppositely.

Further, in the figure, reference numeral 8 indicates a canceling sound generating device, and a signal converting circuit 9 as a signal converting means of this canceling sound generating device 8 and a memory map setting circuit 10 as a filter coefficient storage setting means. , The intake air amount sensor 5
A signal from the crank angle sensor 7 is input.

In the signal conversion circuit 9, the input signal from the crank angle sensor 7 is synchronized with the engine rotation to generate one pulse for two engine revolutions, and in the frequency domain, 0.5 × n (integer of engine revolution). ) A signal having a frequency spectrum of the next component is shaped and processed, and as a noise vibration source signal (primary source), an adaptive filter 11 as a cancel signal synthesizing means, a speaker / microphone transfer characteristic estimating circuit (CMN0 circuit) 12, and Output to.

This is because the vibration noise associated with the 4-cycle engine (FIG. 2 (b)) is caused by the engine 1 rotating twice (720 ° C.).
In order to complete the four strokes of intake / compression / explosion / exhaust in A), there is vibration noise that makes the engine 2 revolutions one cycle. In the frequency range, the 0.5th order component of the engine revolution (the engine 2 revolutions) The frequency spectrum (0.5 × n (integer) order component) is the frequency spectrum (Fig. 2 (d)) in which the sine wave component that becomes one cycle is the fundamental wave and the higher order component is the main component. This is because it is configured by.

In the adaptive filter 11 to which the primary source from the signal conversion circuit 9 is input, the filter coefficient W (n) is set by the memory map setting circuit 10 which will be described later, and LMS (Least Mean Square) which will be described later.
e) FIR (Finite Impulse Res) in which the filter coefficient W (n) set above is updated by the arithmetic circuit 13.
ponse) filter having a predetermined number of taps. The primary source input to this adaptive filter 11 is
The filter coefficient W (n) and the convolution product sum are output as a cancellation signal to the D / A converter 14, and the amplifier 1
5 is generated as a canceling sound from the speaker 16 which is an additional sound source.

The speaker 16 is arranged in a vehicle compartment (not shown), and an error microphone serving as an error signal detecting means, which is a sound pressure sensor, is provided at a listening point (for example, a position close to a driver's ear) in the vehicle compartment. 17 are provided. The error microphone 17 detects the result of interference between the vibration noise and the canceling sound, and inputs the result to the LMS arithmetic circuit 13 as an error signal.

In the speaker / microphone transfer characteristic estimation circuit (CMN0 circuit) 12, the speaker / microphone transfer characteristic CMN is obtained and set in advance, and the above-mentioned primary source from the signal conversion circuit 9 is used as the primary source. Speaker /
The signal is input to the LMS operation circuit 13 after being corrected by being multiplied by the transfer characteristic between microphones CMN.

In the LMS arithmetic circuit 13, the instantaneous square error is obtained from the error signal from the error microphone 17 and the signal from the CMNO circuit 12, and the error microphone 1
The filter coefficient W (n) of the adaptive filter 11 is updated so that the error signal from 7 is minimized.

On the other hand, the memory map setting circuit 10 is
The signal from the intake air amount sensor 5 is converted into an engine load signal LE, the signal from the crank angle sensor 7 is converted into an engine speed NE, and the engine speed NE and the engine load signal are converted as shown in FIG. By LE, the filter coefficient W of the adaptive filter 11
A filter coefficient map MF that can be searched for (n) is stored. And when load fluctuation and rotation fluctuation occur,
A filter coefficient W (n) is newly selected from the filter coefficient map MF and set in the adaptive filter 11, and the filter coefficient W (n) updated by the LMS operation circuit 13 is added to the new map MF. The set value is stored and corrected.

Further, reference character C in FIG. 1 is a transfer characteristic of the vehicle body with respect to vibration noise of the engine 1, and CMN is a transfer characteristic between the speaker 16 and the microphone 17.

Next, the operation of the embodiment having the above construction will be described. First, engine vibration noise is
To a vehicle interior sound through a mount or the like (not shown), and sound of intake and exhaust also propagates into the vehicle interior. As shown in FIG. 2, each of these engine-related vibration noises is composed of a frequency spectrum of a 0.5 × n (integer) order component in the frequency domain, and is multiplied by the vehicle body transfer characteristic C to obtain a listening point. Reach

On the other hand, the signals from the intake air amount sensor 5 and the crank angle sensor 7 of the engine 1 are input to the signal conversion circuit 9 and the memory map setting circuit 10 of the cancellation sound generator 8.

The signals from the intake air amount sensor 5 and the crank angle sensor 7 input to the memory map setting circuit 10 are engine load signals LE and LE, respectively.
Converted as engine speed NE, these signals (L
The filter coefficient W (n) is selected from the filter coefficient map MF by E, NE) and set in the adaptive filter 11.

The signals from the intake air amount sensor 5 and the crank angle sensor 7 input to the signal conversion circuit 9 are synchronized with the engine rotation by synchronizing the signals from the crank angle sensor 7 with the engine 2 revolutions. In the frequency domain, the signal is shaped and processed into a signal having a frequency spectrum of 0.5 × n (integer) order component of the engine rotation in the frequency domain, and the adaptive filter 11 is used as a noise vibration source signal (primary source).
And a speaker / microphone transfer characteristic estimation circuit (CMN0 circuit) 12 are output.

Next, the primary source from the signal conversion circuit 9 input to the adaptive filter 11 is subjected to vibration noise due to convolution product sum with the filter coefficient W (n) set by the memory map setting circuit 10. As a canceling signal that is a canceling sound signal that cancels
The signal is output to a speaker 16 (not shown) in the vehicle compartment via the A / A converter 14 and the amplifier 15, and is output from the speaker 16 as a canceling noise against the vibration noise at the listening point (for example, the position close to the driver's ear). At this time, the canceling sound output from the speaker 16 is multiplied by the speaker / microphone transfer characteristic CMN and reaches the listening point.

Therefore, at the listening point, the engine-related vibration noise and the canceling noise interfere with each other to reduce the vibration noise, and at the same time, the error microphone 17 disposed near the listening point causes The result of the interference between the vibration noise and the canceling noise is detected and sent to the LMS arithmetic circuit 13 as an error signal.

The primary source output to the speaker / microphone transfer characteristic estimation circuit (CMN0 circuit) 12 is multiplied by the speaker / microphone transfer characteristic CMN obtained in advance and sent to the LMS operation circuit 13. .. Then, in this LMS arithmetic circuit 13, an instantaneous square error is obtained from the error signal from the error microphone 17 and the corrected primary source, and the error microphone 17 is obtained.
An algorithm for updating the filter coefficient W (n) of the adaptive filter 11 is carried out so that the error signal from the signal is minimized. The filter coefficient W (n) updated to the optimum value by this algorithm is stored and modified as a new set value of the filter coefficient map MF of the memory map setting circuit 10.

As described above, in the present embodiment, the memory map setting circuit presets the filter coefficient value of the adaptive filter to a suitable value from the engine load information and the engine rotation information, and the LMS algorithm is based on this value. Since it is performed, it is possible to significantly reduce the calculation for updating the filter coefficient even in a transient state such as during rapid acceleration, and follow the operating state to achieve stable noise reduction. be able to.

Further, since a primary source having a very high correlation with engine-related vibration noise can be obtained without using a new sensor such as a vibration sensor, it can be applied to a vehicle which does not have a muffled sound reducing device in the passenger compartment. It can be installed easily.

In this embodiment, an example of the noise reduction device using the LMS algorithm of 1 channel (1 error microphone, 1 speaker) has been described, but the MEFX-LMS in which the LMS algorithm is expanded to multiple channels.
(Multiple Error Filtered X-LMS) algorithm that can be applied to a vehicle interior muffler noise reduction device (for example, a device with four error microphones, four speakers, etc.) and can significantly reduce the calculation of the algorithm. Thus, it is possible to realize a vehicle interior muffled noise reduction device that has better followability during transient operation.

In this embodiment, the engine load information is obtained from the intake air amount sensor. However, the engine load detection means other than the intake air amount, such as the throttle opening and the engine intake pipe negative pressure, is used. You may get it.

Further, in this embodiment, the engine rotation information is obtained from the crank angle sensor, but the engine rotation detecting means other than the crank angle, for example, the signal from the cam angle sensor, the fuel injection pulse, the ignition pulse signal, etc. You may get from.

Further, also for a diesel engine vehicle having a large engine-related vibration noise, the engine load information can be adapted to detect the manifold pressure or the fuel pipe pressure fluctuation of the fuel injection valve.

[Second Embodiment] The drawing shows a second embodiment of the present invention. FIG. 4 is a schematic view of a system for reducing the muffled noise in the passenger compartment, and FIG. 5 is an explanatory view of load information and rotation information of fuel injection pulses. Is. In the second embodiment, the signal detected from the engine is a fuel injection pulse, and from this fuel injection pulse,
The difference from the first embodiment is that the engine load information and the engine rotation information are obtained.

In FIG. 4, reference numeral 21 is an engine control unit (ECU) for setting a fuel injection pulse for the injector 22 of the engine 1 based on various parameters. The injector 22 is arranged in each cylinder,
An optimum amount of fuel is supplied to each cylinder by sequential control.

A cancellation sound generator 23 is connected to the ECU 21, and a signal conversion circuit 24 as a signal conversion means of the cancellation sound generator 23 and a memory map setting circuit 25 as a filter coefficient storage setting means are provided with the above. ECU
One of the injectors 22 calculated in 21 (for example, the engine 1 has four cylinders, and the fuel injection sequence is # 1 → # 3 → #
A fuel injection pulse Ti, which is a control signal for the # 1 cylinder in the case of 2 → # 4), is input.

As shown in FIG. 5, the fuel injection pulse Ti has a fuel injection pulse width (between t1 and t2, between t3 and t4, and between t5 and t6).
Interval) is given as engine load information, and fuel injection pulse intervals (t1-t3, t3-t5, t5-t7) are given as engine rotation information.

Therefore, in the signal conversion circuit 24, the input fuel injection pulse Ti is synchronized with the engine rotation to generate one pulse for two engine revolutions, and 0.5 × n (integer number) of the engine revolution in the frequency domain. ) A signal having a frequency spectrum of the next component is shaped and processed, and as a noise vibration source signal (primary source), an adaptive filter 11 as a cancel signal synthesizing means, a speaker / microphone transfer characteristic estimating circuit (CMN0 circuit) 12, and Output to.

On the other hand, in the memory map setting circuit 25, the fuel injection pulse width of the fuel injection pulse Ti is converted into the engine load signal LE, the fuel injection pulse interval is converted into the engine speed NE, and the engine speed NE is converted into the engine speed NE. A filter coefficient map MF in which the filter coefficient W (n) of the adaptive filter 11 can be searched by the engine load signal LE is stored. And load fluctuation,
When rotation fluctuation occurs, a new filter coefficient W (n)
From the filter coefficient map MF and set in the adaptive filter 11, and the LMS operation circuit 1
The filter coefficient W (n) updated in 3 is stored and corrected as a set value on the new map MF.

The other structure and operation are the same as those of the first embodiment.

As described above, in the second embodiment, since the engine load information and the engine rotation information are obtained from the fuel injection pulse, the sensor for detecting the engine load is unnecessary and the system is constructed at a low cost. It is possible to deal with aftermarket easily.

The second embodiment can also be applied to the vehicle interior muffler noise reducing apparatus using the MEFX-LMS algorithm, as in the first embodiment.

[0042]

As described above, according to the present invention,
By presetting the filter coefficient of the adaptive filter according to the operating condition of the engine, it is possible to reduce the amount of algorithm calculation processing, so it has excellent followability and stability not only during steady running but also during transient operation. Noise can be reduced.

[Brief description of drawings]

FIG. 1 is a system schematic view of a vehicle interior muffled noise reducing apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a correlation between a primary source and vibration noise according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a filter coefficient map according to the first embodiment of the present invention.

FIG. 4 is a system schematic view of a vehicle interior muffled noise reducing apparatus according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of load information and rotation information of a fuel injection pulse according to the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 engine 5 intake air amount sensor 7 crank angle sensor 9 signal conversion circuit (signal conversion means) 10 memory map setting circuit (filter coefficient storage setting means) 11 adaptive filter (cancellation signal synthesis means) 12 speaker / microphone transfer characteristic estimation circuit 13 LMS arithmetic circuit (cancellation signal updating means) 16 speaker (cancellation sound generating means) 17 error microphone (error signal detecting means) LE engine load signal MF filter coefficient map NE engine speed Ti fuel injection pulse W (n) filter coefficient

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location H04B 1/10 L 9298-5K (72) Inventor Kazuyuki Kondo 1-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 2 inside Fuji Heavy Industries Ltd.

Claims (1)

[Claims] 1. A signal conversion means for detecting load information and rotation information of an engine and converting the load information and rotation information as a noise vibration source signal having a frequency spectrum composed of predetermined high order components, and an adaptive filter for the noise vibration source signal. A cancel signal synthesizing means for synthesizing as a cancel signal, a canceling sound generating means for generating the cancel signal from a sound source as a canceling sound for noise, an error signal detecting means for detecting a noise reduction state at a listening point as an error signal, and the above error A cancel signal updating means for updating the filter coefficient of the adaptive filter based on the signal and the noise and vibration source signal, and the filter coefficient of the adaptive filter to a preset value from the load information and the rotation information of the engine. At the same time, write this set value in the value updated by the cancellation signal updating means. Cabin muffled sound reducing device characterized by comprising a filter coefficient storage setting means for modifying.