JPH08297493A - Silencing system - Google Patents

Abstract

PURPOSE: To generate a reference signal which simplifies the processing of adaptive filters. CONSTITUTION: In the silencing system which processes an adaptive filter 300 so as to form signals silencing noises by inputting periodic signals relating to noises as reference signal, the pulse signals obtained by shaping the periodic signals are multiplied by a specified number of times. A multiplication/counting circuit 110 which counts multiplication signals over this one period in synchronization with the pulse signals to detect the angular phases of the periodic signals and a sinusoidal table 320 which stores the sinusoidal values making one-to-one correspondence with the angular phase that are formed by the count and the order showing the fundamental wave and high-frequency waves based on the number of multiplication using the count of the multiplication signals as address are installed. The adaptive filter 300 singly uses the sinusoidal values covering the fundamental wave to high-frequency waves of the siunusoidal table 320 readout with a certain timing based on the count of the multiplication/counting circuit as reference signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencing system for actively silencing rotational noise of a rotating body caused by an internal combustion engine, and particularly to a reference signal required by an adaptive filter for silencing control. The present invention relates to a muffling system for generating.

[0002]

2. Description of the Related Art In a conventional sound deadening system, adaptive filter processing is performed using a reference signal related to noise as a controlled signal. For example, Japanese Patent Application Laid-Open No. 3-190971 discloses a reference signal generation device for generating such a reference signal, and this reference signal generation device measures the ignition period or the generation period of a crank angle signal pulse. And a sine wave table storing sine numerical values, and generating a sine value synchronized with a combustion cycle or its high frequency as a reference signal without using an external oscillator.

[0003]

However, in the above reference signal generator, not only the first sensor that outputs the basic cycle of the engine (rotation or fuel cycle) but also the output of the first sensor is synchronized, It also requires a second sensor that produces a harmonic output that is a division of the period of this signal. As a result, in a vehicle that does not use the two-system rotation sensor, a diesel vehicle, or the like, it is necessary to newly install a sensor, which causes a problem that the vehicle mountability of the noise reduction system and the cost are deteriorated. .

Further, in this reference signal generator, one cycle of the basic sine wave is subdivided by the angle phase as the sine wave table, but when calculating the basic cycle of the engine and its high frequency from this table, it is complicated. However, there is a problem that the burden of the calculation for simultaneously muffling various sounds having different frequencies becomes heavy. The above-mentioned problem is that a phase shift of a sine wave is likely to occur under conditions where the engine speed fluctuates greatly in a short time such as during acceleration or deceleration, and an accurate (synchronized with the engine) reference signal is generated. There is the further problem of becoming difficult.

Therefore, in view of the above problems, it is a first object of the present invention to provide a muffling system capable of improving vehicle mountability and cost. In view of the above problems, it is an object of the present invention to provide a second silencing system that can reduce the burden of calculation. In view of the above problems, it is an object of the present invention to provide a third silencing system capable of generating an accurate reference signal.

[0006]

In order to solve the above problems, the present invention provides a muffling system having the following configuration. That is, a periodic signal related to noise is input as a reference signal to a silencing system that performs adaptive filter processing to form a signal that silences noise, and a pulse that is shaped from the periodic signal input from one sensor. To multiply the signal to a predetermined number and detect the angular phase of the periodic signal,
In synchronization with the pulse signal, a multiplying / counting circuit that counts the multiplied signal over this one cycle, and the count of the multiplied signal as an address, and the count, the fundamental wave, and the high frequency are shown based on the multiplied number. There is provided a table for storing the sine value corresponding to the angular phase formed by the order and the one-to-one relationship in a map form. The adaptive filter reads the sine value from the fundamental wave to the high frequency of the table at a constant timing based on the count of the multiplication / counter circuit and uses it as a reference signal independently.

The periodic signal input to the multiplier / counter circuit is any one of a combustion synchronization signal, a cam rotation synchronization signal, a crank rotation synchronization signal, a transmission rotation signal and a tacho signal which are synchronized with the engine rotation. It is as it is. Further, the multiplication / counting circuit may use a dedicated arithmetic unit in addition to the adaptive filter.

Further, in the table, when the multiplication number is n and the maximum order of the high frequency is m0, the multiplication number n is set to a prime number such that n> 2m0.

[0009]

According to the silencing system of the present invention, the adaptive filter ranges from the fundamental wave of the sine table having a sine value corresponding to the angle phase to the high frequency based on the count of the multiplication / counting circuit. By reading out the sine value of at a fixed timing and using it independently as a reference signal, various sounds with different frequencies are not silenced at the same time as in the conventional case, so the calculation load is reduced. In particular, under conditions where the engine speed fluctuates greatly in a short time such as during acceleration or deceleration, the phase shift of the sine wave does not occur, and it becomes possible to generate an accurate reference signal. A combustion synchronization signal synchronized with engine rotation, a cam rotation synchronization signal, a crank rotation synchronization signal,
Either the transmission rotation signal or the tacho signal can be selected, so that the vehicle mountability of the noise reduction system is improved. Further, the multiplication / counter circuit can use a dedicated arithmetic device in addition to the adaptive filter to increase the arithmetic speed of the adaptive filter. In the sine table, the multiplication number is n, and the maximum order of the high frequency is m.
If the multiplication number n is set to be a prime number such that n> 2m0 when 0, uniform convergence can be obtained when performing adaptive filter calculation of all high-frequency components of order m0 or lower. To

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a silencing system according to an embodiment of the present invention. As shown in the figure, the muffling system includes a speaker 400 that receives an interference signal for muffling noise and converts it into muffling, an error sensing microphone 200 that detects the muffling result sound as an error signal,
A preamplifier 210 that amplifies the error signal and an A / D converter 220 that converts the error signal from analog to digital
(Analog to Digital Converter), a power amplifier 410 that drives the speaker 400, and a D / A converter 4 that changes an analog signal to the power amplifier 410 from a digital signal.
20 (Digital to Analog Converter), a rotation signal of the engine is inputted as a periodic signal, and a shaping circuit 100 for shaping in a pulse shape, and a multiplication signal of a predetermined number n times synchronized with the output of the shaping circuit 100 And a multiplying / counting circuit 110 for counting the multiplied signal over one cycle of the input signal and detecting a real-time angle phase based on the cycle of the input signal, and the multiplying / counting circuit 110.
The parallel port 120 for inputting the angle phase signal detected in step S1 and the reference signal (sin data) in which the angle phase signal is read from the multiplying / counting circuit 110 through the parallel port 120 and the angle phase and the sine table are associated with each other. Is generated, the digital error signal from the A / D converter 220 is input, an interference signal is generated using the reference signal and the error signal, and the digital interference signal is input to the D / A converter 420. Output DSP300 (Digital Signal P
a ROM 320 (Read Only Memory) that stores the sine table and an adaptive filter that performs an operation for generating an interference signal in the DSP 300. A RAM 310 (Random Access Memory) is provided.

It should be noted that, as the engine rotation signal input to the shaping circuit 100, a combustion synchronization signal, a cam rotation synchronization signal, and a crank rotation angle signal are mainly assumed, but in the present system, the principle is used. Therefore, any signal that is proportional to the engine speed, such as a transmission rotation signal or a tacho signal, can be selected and treated as an input signal.

FIG. 2 is a diagram showing a time chart from the input of the rotation signal of the engine of FIG. 1 to the generation of the angle phase signal. As shown in this figure (a), the periodic signal from the engine is shaped into a pulse as shown in this figure (b) through the shaping circuit 100, and the multiplication / counting circuit 11 of the next stage is formed.
Output to 0. In the multiplication / counter circuit 110, a predetermined multiplication number n (= 12) is applied to one cycle of the shaped periodic signal.
The pulses at equal time intervals are generated as shown in FIG. 7C, and the multiplying / counting circuit 110 counts the pulses over the negative period of the periodic signal as shown in FIG.
Then, the multiplication / counting circuit 110 causes the parallel port 120 to latch the result of the count N as an angle phase in real time. In this way, the count output, which is the output of the multiplication / counter circuit 110, generates a stepwise triangular wave on the parallel port 120 in synchronization with the combustion or rotation cycle. This signal is D
It is independent of the operation of SP300, and DSP300
Can read this signal at any timing.

FIG. 3 is a diagram for explaining the operation of the DSP 300 reading a sine value from the ROM 320, and FIG. 4 is a diagram showing a sine value table stored as map data in the ROM 320 of FIG. As shown in FIG.
When the multiplication number n = 31, the count output N is the angle phase (ra
It corresponds to d). Further, FIG. 3C shows that the fundamental wave m =
1 is the map value read by the DSP 300 when the multiplication number n = 31, and FIG.
9 is a map value read by the DSP 300 when the multiplication number n = 31. The DSP 300 reads out this count output N at a predetermined timing, and outputs this count output N and R
The map data in the OM 320 is mechanically made to correspond to 1: 1 and the sine value corresponding to the corresponding angular phase is shown in FIG.
As shown in (c), it is read from the ROM 320. Here, the map data in the ROM 320 is configured as shown in FIG. 4, where n is the multiplication number and m is the maximum number of characters, and the current position N (N = N) of the triangular wave that is the count output.
0 to n-1) and the index pointer PN on the address in the ROM 320 corresponding to N, the map value of the high frequency sine value s (n, m) up to the m-th order is sin (2mπN / ωn). Is. Note that | s (n, m) | ≦ 1.

Here, the multiplication number n is set to be a prime number larger than a value m0 which is twice the maximum order to be muted (n> 2m0), and the map contents are also shown in FIG. As shown, the map shape is m0 × n in accordance with this. As described above, n> 2m0 means that when a sine wave is digitally restored from a table, at least two or more data points must exist within one cycle of the target sine wave from the sampling theorem. Since the sine wave of the shortest wavelength on the above map is when the order is the maximum order m,
This is because the condition of n> 2m0 is indispensable from the above sampling theorem.

Further, as described above, the use of the multiplication number n as a prime number means that the convergence of each order component is as follows.
This is to improve it uniformly. FIG. 5 is a diagram illustrating an example of uniformly improving the convergence of each order component. The above convergence will be described by comparing FIGS. 5 and 3. First,
FIGS. 3B and 3C show data points of the sine wave and the fundamental wave when m = 9. The count output value N in FIG. 3A forms a staircase wave that changes from 0 to 30, and
The data indicated by the arrow in the figure is taken into the DSP 300 according to the value of the count output N referenced by 00. In FIG. 3, the value of n is 31, whereas in FIG.
The value of n is 36. 3 and 5, FIG.
There is no particular problem with the fundamental wave of (a) and FIG. 5 (b),
Comparing the states of the data in the case of m = 9 in FIG. 3 (b) and FIG. 5 (a), while there is no periodic repetition of data points in the figure in FIG. 3 (b), In FIG. 5 (a), there are periodic repetitions of data points in the figure. Due to this periodic repetition, for example, in FIG. 5A, another higher-order component is added to the signal that should originally be input as a sine wave, and the waveform is not the original sine wave, and the dotted line in FIG. Like a section, it will be treated as a triangular wave. Therefore, in the next stage adaptive filter,
Since this data is calculated by multiplying it by the filter coefficient, the solution can be obtained in a form including frequency components other than the original sine wave. Since this extra frequency component acts in synchronization with the original frequency component, sin (2mπN / ωn), it does not have the property of being canceled out in the process of calculation like random noise and disappearing,
As a result, the convergence of the filter calculation is worse than when the original sine wave is input. On the other hand, as shown in FIG. 3, when an appropriate prime number is used, all the signals input to the adaptive filter are regarded as single-period sine waves, so that for all order components that are the target of muffling. Therefore, uniform convergence can be obtained.

In the present invention, the process of synthesizing the individual reference signals (digital data) generated as described above is not performed, and for the purpose of simplifying the model and reducing the number of operations of the adaptive filter as much as possible, The feature is that a plurality of reference signals are used individually as follows. Figure 6 is D
It is a figure which shows the flowchart explaining a series of processes of SP300.

In step S1000, the DSP 30
0 is a predetermined timing such as a sampling time interval, and the count output N is read from the multiplication / counter circuit 110. In step S1010, the DSP 300 uses the internal program to generate the address index P corresponding to the count output N.
Set N. In step S1020, the order k of the high frequency for which data is to be generated by the internal program as well.
Select However, m> k.

In step S1030, in order to read out the desired data, the address P is obtained as P = PN + k-1 as shown in FIG. In step S1040, the map value is read from the address P as sin (2kπN / ωn).

In step S1050, this map value is used in the arithmetic processing of the adaptive filter. In step S1060, after the above operation is completed, it is determined whether or not the specified number of k's are selected by the internal program, and if all k's can be selected, this routine is ended. If the selection of k does not satisfy the specified number, the process proceeds to step S1070.

In step S1070, the next k is selected, and the flow returns to step S1030 to generate another frequency map value. In addition, the configuration of FIG.
Adaptive filter operation unit and multiplication / counter circuit 11 by 300
However, if the DSP 300 has a sufficient processing capacity, the DSP 300 internal processing for uniquely associating the equivalent signal phase with the sine wave map without using the multiplication / counting 110 is performed. Alternatively, the configuration may be realized.

The configuration of FIG. 1 includes a speaker 40.
0, the microphone 200, the DSP 300, and the like are shown as a single unit, but the present invention is also applicable to the case where a plurality of the above elements are present in the system. Further, as the configuration of FIG. 1, a shaping circuit 100, a multiplication / counter circuit 110, an A /
D converter 220, D / A converter 420, amplifier 210,
The 410, the RAM 310, the ROM 320, and the DSP 300 are shown as individual elements, but in a system in which the above-described components are combined into a single IC chip for the purpose of circuit miniaturization and cost reduction, among the above-mentioned components, The present invention is valid regardless of whether a part or all of the above are synthesized.

Therefore, according to the reference signal generation according to the embodiment of the present invention, the input of the periodic signal used for generating the reference signal of the silence system is sufficient for one system, and the silence system can be easily mounted on the vehicle. Further, any signal can be selected as long as it is a signal synchronized with the engine rotation. Further, with respect to the synchronization of the input signal used for generating the reference signal, first, the cycle of the input signal is multiplied by a predetermined multiplication number, and then the multiplied signal is counted to obtain a phase angle. By associating the tables with each other at 1: 1, it is possible to quickly generate the reference signal because a complicated calculation as in the past is not required.

Further, the signal generated as a sine wave when the sine wave is generated based on the multiplied signal is not used by combining a plurality of sine signals having different frequencies on the input side, and a plurality of sine signals having different frequencies are independently used. By adopting the configuration to be used selectively,
The operation of the adaptive filter at the next stage can be performed easily and at high speed. By determining the multiplication number n of the input signal cycle used to generate the reference signal to be a prime number n> 2m0 with respect to the maximum order m0 of the harmonics that need to be adaptively filtered, Uniform convergence is now obtained when performing adaptive filter calculation of high frequency components.

[0024]

As described above, according to the adaptive filter, the sine value from the fundamental wave to the high frequency of the sine table having the sine value corresponding to the angular phase on a one-to-one basis is fixed based on the count of the multiplication / counter circuit. Since it is read out at the timing of 1 and used as a reference signal independently, various sounds with different frequencies are not silenced at the same time as in the conventional case, and the load of calculation is reduced.
In particular, under conditions where the engine speed fluctuates greatly in a short time such as during acceleration or deceleration, the phase shift of the sine wave does not occur, and it becomes possible to generate an accurate reference signal. As the periodic signal input to the multiplication / counting circuit, any one of a combustion synchronization signal, a cam rotation synchronization signal, a crank rotation synchronization signal, a transmission rotation signal, and a tacho signal that are synchronized with the engine rotation can be selected. The mountability is improved. Since the multiplication / counting circuit is a dedicated arithmetic unit in addition to the adaptive filter, the arithmetic speed of the adaptive filter can be increased. In the sine table, when the multiplication number is n and the maximum order of high frequency is m0,
Since the multiplication number n is defined as a prime number such that n> 2m0,
It is possible to obtain uniform convergence when performing adaptive filter calculation of all high-frequency components of order m0 or lower.

[Brief description of drawings]

FIG. 1 is a diagram showing a silencing system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a time chart from the input of a rotation signal of the engine of FIG. 1 to the generation of an angle phase signal.

FIG. 3 is a diagram illustrating an operation of DSP 300 reading a sine value from ROM 320.

FIG. 4 is a diagram showing a sine value table stored as map data in a ROM 320 of FIG.

FIG. 5 is a diagram illustrating an example of uniformly improving the convergence of each order component.

FIG. 6 is a diagram illustrating a flowchart illustrating a series of processes of the DSP 300.

[Explanation of symbols]

 100 ... Shaping circuit 110 ... Multiplication / counting circuit 300 ... DSP 320 ... Sine table

Front Page Continuation (72) Inventor Yoshihiro Nakase 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc.

Claims (4)

[Claims] 1. A silence system for performing an adaptive filter process to input a periodic signal related to noise as a reference signal to form a signal for silencing the noise, in order to detect an angular phase of the periodic signal. A multiplying / counting circuit that multiplies a pulse signal obtained by shaping the periodic signal input from one sensor into a predetermined number, and synchronizes with the pulse signal, counts the multiplied signal over this one period; Based on the count value of the signal as a radix, a table for storing the angular phase formed by the fundamental wave and the harmonics corresponding to this one cycle and the sine value corresponding to one to one in a map is provided, and the adaptive filter, The sine value from the fundamental wave to the highest-order high frequency in the table is read out at a constant timing based on the count value of the multiplier / counter circuit and is used as a reference signal independently. Silencer system. 2. The cycle signal input to the multiplication / counting circuit is any one of a combustion synchronization signal, a cam rotation synchronization signal, a crank rotation synchronization signal, a transmission rotation signal and a tacho signal which are synchronized with engine rotation. The silencing system according to claim 1, characterized in that there is. 3. The sound deadening system according to claim 1, wherein the multiplier / counter circuit uses a dedicated arithmetic unit in addition to the adaptive filter. 4. The table, wherein the multiplication number is n,
When the maximum order of the high frequency is m0, the multiplication number n
Is defined as a prime number such that n> 2m0,
The sound deadening system according to claim 1.