JPH02306843A - Device for reducing indoor noise - Google Patents

Abstract

PURPOSE:To reduce noise component by synchronizing the sinusoidal wave output of an oscillator having a determined rotation order component corresponding to an engine speed with the engine rotation, and processing the sinusoidal wave output by the phase control quantity and sound pressure control quantity preliminarily stored in the determined rotation order component, respectively. CONSTITUTION:A condition judging part 52 controls to generate each sinusoidal output signal from an oscillator selected from oscillators 61-6n corresponding to the rotation order component preliminarily selected corresponding to an engine speed, synchronously with TDC of the engine rotation. In ROM 53, the phase control quantity phi and sound pressure control quantity G in all rotation order components corresponding to the engine speed from the judging part 52 are outputted and given to a phase control part 54 and a sound pressure control part 55, respectively, in which each sinusoidal wave output signal synchronized with the engine rotation (TDC) from the oscillators 61-6n is processed to delay the phase by the portion of the corresponding determined value. An original waveform as reducing-sound pressure to the maximum extent is given to an amplifier 7 through a band-pass filter 56.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for reducing noise inside a vehicle, and more particularly to a device for actively reducing low-frequency noise in a closed space such as an automobile that has a periodic sound source. It is something.

[Conventional technology]

Noise inside a vehicle such as a car is caused by the resonance phenomenon that occurs in the cabin, which forms a closed space, under certain conditions.
The vibrational force that is the cause of this is thought to be due to the rotational vibration component of the engine.

The measures initially taken to reduce such noise were passive, such as improving the coupling rigidity of the engine system, which is the source of vibration, and improving the coupling rigidity of the transmission system. We have tuned each mount and created a panel rigid amplifier for the sounding element inside the vehicle.
Furthermore, as a countermeasure against resonance, mass dampers, Guinamisoku dampers, etc. were applied to the resonant parts.

Such aggressive means lead to an increase in cost and weight, and the effects are not fully satisfactory.

For this reason, JP-A-48-82304 and JP-A-59
A device capable of actively reducing noise has been proposed in Japanese Patent No. 9699 and the like.

In particular, the latter Japanese Patent Application Laid-open No. 59-9699 describes a four-cylinder vehicle in which muffled noise is a problem. Processes pulse signals in various ways,
By separately adding a sound from a speaker that is in the opposite phase of each frequency component (rotational order component) of quiet sound observed at the driver's listening point in the vehicle and whose size is the same as the noise component, the sound can be heard through the interference effect. This offsets and reduces the noise level at the point.

[Problem to be solved by the invention]

However, the above-mentioned conventional example is a device for reducing only the muffled noise caused by the secondary component of engine rotation (primary explosion component) of the noise inside the vehicle;
The problem is that even if there is a noise component caused by a rotation order component (explosion order component) other than the rotation second order component (explosion first order component) caused by rotation), it cannot be removed and noise reduction is not optimal. There was a point.

Therefore, an object of the present invention is to realize a device that can remove not only the muffled sound in the vehicle interior but also noise components other than the muffled sound caused by engine explosion.

[Means to solve the problem]

In order to achieve the above object, the vehicle interior noise reduction device according to the present invention includes: a means for detecting a rotational order component due to an engine explosion; an oscillator, and a sine wave output of the oscillator of a predetermined rotation order component corresponding to the engine rotation speed detected by the detection means, which is synchronized with the engine rotation, and a pre-stored phase control amount for the predetermined rotation order component; and a control means for respectively processing the sine wave output according to a sound pressure control amount, and an amplifier for amplifying the output of the control means and driving a speaker.

[For production]

Figure 8 is a waterfall diagram showing the sound pressure level of the 1st to 8th rotation order components caused by the explosion of a four-cylinder engine.These rotation order components cause cabin noise, but these rotation order components are , which is generated based on the intellectual force of the piston and the explosive force within the cylinder.

Therefore, the ignition (ignition) point of the engine that brings about such each rotational order component is determined, and the delay time ti (9th
If the phase of the sine wave signal from the oscillator synchronized with the ignition timing is determined in advance (see Figure fa), the engine interior noise component can be reduced.

On the other hand, the time α from the top dead center (hereinafter referred to as TDC) to the ear, which is the listening point, for the rotational order component shown in FIG. 9(a) is the transmission of nonlinear characteristics from engine mount → cab → cabin space. It depends on the route and is considered to be an approximately constant time.

Therefore, how far should the phase of the sine wave signal from the oscillator synchronized with the engine rotation (TDC) be advanced for each rotation order component to reduce the noise when the time from ignition (ignition) to TDC becomes t1-α? Is it possible to measure the engine rotation speed in advance and use the control means to control the phase side? It may be stored as 311.

In addition, in order to optimally reduce noise, it is necessary not only to control the phase but also to control the sound pressure corresponding to the sound pressure of the noise (reverse phase control). Each component is measured in advance in correspondence with the engine speed and stored in the control means as a sound pressure control amount.

Then, an oscillator is prepared for each rotational order component shown in Fig. 8, and among these rotational order components, a component with a particularly high sound pressure level is selected, and among these, the component detected by the engine rotational order component detection means is selected. A control means energizes the oscillators corresponding to all rotation order components corresponding to the engine rotation speed and synchronizes the sinusoidal output signal with the engine rotation.

In addition, the phase side 21H15 stored in the control means and the phase side UIlfJ in the predetermined rotational order component corresponding to the detected current engine rotational speed among the sound pressure control amount
And sound pressure side? 8Jli is output.

Then, the control means processes the sine wave output signal of the oscillator of each rotational speed order component corresponding to the phase control amount and the sound pressure control η amount, and amplifies these processed signals with an amplifier, thereby controlling the loudspeaker. A signal component capable of canceling noise of a predetermined rotational order component is output from the motor.

〔Example〕

FIG. 1 shows the overall configuration of a vehicle interior noise reduction device according to the present invention, where l is a car and 2 is a car! 3 is a crank angle sensor for the engine 2; 4 is a temperature sensor installed in the engine 2; 5 is a controller as a control means for performing predetermined calculations based on the outputs of the sensors 3 and 4; 6. ~6n (n>l) is each rotational order (
n oscillators are provided in the controller 5 corresponding to the 1st to 8th order) components and output sine wave signals synchronized with engine rotation, and 7 is an oscillator 6 from the controller 5. ~6
, is an amplifier for amplifying and combining the outputs of the speakers 8 and 8 to drive the speaker 8. In this example,
The engine used is a four-cylinder engine, and the crank angle sensor 3 detects each rotational order component from the number of rotating gears within a reference time of a magnetic gear 10 provided coaxially with the crankshaft 9, for example, as shown in FIG. This constitutes the φ means. Moreover, the reason why the signal line of the engine temperature sensor 4 is shown as a dotted line is that it is not essential as will be described later.

FIG. 2 shows an embodiment in which the controller 5 is particularly shown as a functional block in the vehicle interior noise reduction device shown in FIG. A condition determination unit 52 that manually determines various conditions based on the engine rotation speed (and engine temperature from the temperature sensor 4 if necessary); Accordingly, the phase control amount φ for each rotational order component of the engine
and a ROM 53 that outputs the sound pressure control amount G, and an oscillator 61.
A phase control unit 54 that controls the phase of each sine wave output signal from ~6o by each phase control amount φ from the ROM 53;
And, is the sound pressure of each sine wave output signal from the oscillators 61 to 61 controlled by the ROM 53? a sound pressure control section 55 controlled by a quantity G; and an oscillator 6 whose phase and sound pressure are controlled. .about.67, and a bandpass filter 56 that passes only the desired frequency components of each of the sine wave output signals and sends them to the amplifier 7.

In addition, in FIG. 2, the bandpass filter 56 and the amplifier 7
is for processing the eight outputs of the phase control section 54 and the sound pressure control section 55 individually (omitted in the figure for simplicity), and these are combined by the amplifier 7 and output to the speaker. It is designed to be given to 8. Further, the filter 56 may be used as the location for synthesis.

Next, an explanation will be given of the operation of the embodiment in the case where the engine temperature from the temperature sensor 4 shown in FIG. 2 is not used.

First, the counter section 51 counts engine rotation speed pulses (corresponding to TDC) from the crank angle sensor 3 and provides them to the condition determination section 52.The condition determination section 52 manually calculates the engine rotation speed. An oscillator 6. ~6
The oscillators selected from among the oscillators are controlled so that each sine wave output signal is generated in synchronization with the TDC of the engine rotation.

The rotational order components to be selected in advance in this case are explained using the three-dimensional graph diagram (waterfall diagram) in Fig. 8. The rotational order components shown in the figure are due to engine rotation (explosion), and among these, , in this example, rotations 2 to 4 as shown in the figure.
(2/2.5/3/3.5) Among the following components, A-H is focused on and selected because it has the highest sound pressure level of vehicle interior noise.

Therefore, n oscillations H6, to 67 are 6. You only need to prepare 4 pieces of ~6°, and the engine speed control range shown in Figure 8■
, the oscillator 61 corresponds to the part A of the rotational second-order component, and the oscillator 64 corresponds to the part G of the rotational fourth-order component in the control range ■.
, in the control range ■, the oscillator 6.corresponds to the rotational second-order component part B and the rotational fourth-order component part G. ．． 6. ), and in the control range ■, part C of the rotational second-order component, part of the rotational 2.5th-order component, part E of the rotational third-order component, part F of the rotational 3.5th-order component, and part H of the rotational fourth-order component. Oscillators 61 to 6 corresponding to .
is selected, and a sine wave output signal synchronized with engine rotation is generated.

Therefore, when the condition determining unit 52 confirms that the engine speed detected by the crank angle sensor 3 belongs to the control target range shown in FIG. The phase control amount φ and the sound pressure control f#G are selected and read out for each of the rotation order components corresponding to the current engine rotation speed (.5/3/3.5 order components).

Here, to explain the ROM53, this ROM5
The mamp stored in Fig. 3 is used to control the phase and sound pressure ff so that the protruding part in each rotational order component in Fig. 8 becomes small.
1 (control amount based on the sine wave output from the oscillator) is experimentally determined. For example, the output of only one of n oscillators is variable while the other oscillators are fixed. The phase control obtained for the engine rotation speed in the rotation order component related to the variable oscillator? nf
It is formed by ftφ and the sound pressure control amount G.

In the ROM 53 formed in this manner, there is a phase system for all rotational order components corresponding to the engine rotational speed from the condition determining section 52. 11ftφ and sound pressure control IG
(opposite phase) is output and given to the phase control section 54 and the sound pressure control section 55, respectively, and the S generators 61 to 6. ．． Each sinusoidal output signal synchronized with the engine rotation (TDC) from give to The amplifier 7 adjusts the human signals to the optimum volume, synthesizes them, and outputs them from the speaker 8.

FIG. 3 shows another embodiment, in which
Engine salt + from temperature sensor 4 shown in dotted line in Figure 1
This is an attempt to perform more precise noise reduction using ffi.

That is, the delay time Li shown in FIG. 9 (al) is
~(d) Drink] ~As shown in L3, the temperature increases as the engine temperature increases (the ignition point is delayed in the case of a diesel engine).

This is because when the temperature decreases, it takes time to atomize the fuel necessary from the time of injection to ignition and to raise the temperature of the combustion chamber.

Therefore, when controlling the phase of vehicle interior noise, it is necessary to take temperature into consideration.

Also, the noise inside the car! In order to reduce A appropriately, it is necessary not only to control the phase but also to control the sound pressure (reverse phase control) corresponding to the noise inside the vehicle, but this sound pressure is also affected by temperature changes.

In other words, when the engine temperature is low (warming up in a cold state), the time from injection to ignition is long, and since combustion starts all at once, the sound pressure of the muffled sound due to diesel knock increases; As the aircraft advances and the engine gradually warms up, the diesel engine noise decreases and the noise sound pressure decreases.

After warming up, as the engine temperature increases, the viscosity of the fuel 4 decreases due to the increase in the temperature of the fuel itself and the temperature of the fuel pipe, and the fuel injection amount decreases. For this reason, the amount of fuel is normally increased to compensate for the decrease in output, but the amount increases too much, causing the cylinder pressure to rise and the noise sound pressure to increase.

In this way, as shown in Figure 3, to reduce cabin noise, the engine temperature (detected by a cooling water temperature sensor or fuel temperature sensor installed in the engine) is detected, and as the temperature changes, the engine temperature is detected. Preferably, the phase and sound pressure are controlled.

Therefore, how to control the phase and sound pressure of the sine wave signal synchronized with the engine rotation according to the engine rotation speed and engine temperature may be determined in advance and stored in the control means.

For this reason, in FIG. 3, if another ROM 60 is prepared and the phase and sound pressure are processed from the sine wave signal from the oscillator synchronized with the TDC signal output from the condition determination section 52, it is possible to It is possible to reduce the noise inside the vehicle.

To create the mamp stored in the ROM 60 in the example shown in FIG. 8, first, the sine wave output signal (synchronized with the engine rotation) of the oscillator 61 regarding the second-order component of engine rotation is shown in FIG. In the control target range, a sound reduction experiment was conducted at predetermined intervals (for example, engine rotation speed at every 10100 rpm and engine temperature at every predetermined interval (for example, 10°C) (however, other oscillator outputs were stopped),
Is it possible to control the phase by sequentially finding the phase where the noise is reduced the most at the listening point (at a certain timing α)? ilff
A tROM map can be created.

Next, a similar experiment was performed on the oscillator 6 for the 2.5th order component, and the phase control amount ROM of the 2.5th order component was determined.
Create a map. In this way, four oscillators 6. ~
6. A phase control amount ROM map is created for all.

Regarding the sound pressure G, experiments were similarly conducted for engine speeds and engine temperatures that fall within the control target range shown in Figure 8, and the sound pressure at which the noise was most reduced at the listening point was sequentially determined. A sound pressure control fiROM map can be created.

The ROM map 60 created in this way is based on the engine speed manually input to the condition determination unit 52, and the phase control amount at the current engine temperature for all rotation order components corresponding to the engine speed.・Sound pressure control 17
By processing the outputs from the corresponding oscillators by the phase control section 54 and the sound pressure control section 55, the noise can be optimally reduced.

However, when the engine temperature changes from low temperature to normal temperature to high temperature, it is common that the water temperature does not rise at normal temperature after warming up, so low temperature to normal temperature is controlled by water temperature, and normal temperature to high temperature is controlled by fuel temperature. It is necessary to control the Note that it is also possible to perform control using the intake air temperature during the switching from water temperature to fuel temperature.

By performing phase and sound pressure control based on temperature changes, for example, compared to performing only muffled sound control determined at room temperature for all temperatures, in water temperature control mode, as the temperature decreases, The effect of reducing muffled noise is greater, and the fuel (intake temperature) control? ffl 'E-do, the muffled sound reduction effect becomes more noticeable as the temperature rises above room temperature.

In the above embodiment, a ROM of engine speed-phase/sound pressure with engine temperature as a parameter for each order component is used.
It is necessary to create a map, which results in a fairly large amount of data.

Therefore, instead of converting everything into ROM as described above, each output of the ROM 53 used in the embodiment shown in FIG. 2 may be temperature-corrected by using, for example, an analog correction circuit based on the engine temperature. .

That is, when the condition determination unit 52 gives the engine speed to the ROM 53, the ROM 53 reads out the phase control amount and sound pressure control amount from the ROM map of each order component whose engine speed is within the control range. The analog correction circuit is given the engine temperature from the condition determining section 52, and adds the phase and sound pressure corresponding to this engine temperature to the phase side i11 ift/sound pressure output from the ROM 53, and adds the phase and sound pressure corresponding to the engine temperature to the corresponding output of the output W2S6+ to W2S67. The output is controlled by the phase control section 54.
, can be processed by the sound pressure control section 55.

In addition to the above examples, g4. By preparing a ROM that further takes into account the load detected using a load sensor and performing similar sound pressure control using this, it becomes possible to further cancel out noise that varies depending on the load.

This is because, for example, in a diesel engine, when the normal load increases, the advance angle correction is performed by the load timer and the sound pressure also increases.

On the other hand, in the case of the above embodiment, the oscillator output is based on the TDC of the engine rotation from the crank angle sensor 3, and is controlled based on the engine temperature. It is more direct and preferable to detect the engine ignition or ignition explosion timing itself, which is the main factor, and control the phase and sound pressure.

Therefore, in the embodiment shown in FIG. 4, in the case of a diesel engine, an ignition sensor 80 is installed, which is either a single ignition sensor 80 or a plurality of ignition sensors as shown in FIG. a)), and upon receiving this ignition output waveform, the condition determining section 52 detects the engine rotational speed based on this signal and sends a reference signal of the shaped waveform (■ in the same figure) to each corresponding oscillator. (In addition, the condition determination unit 5
2 detects the engine speed based on the ignition output waveform, so in this case, the rank angle sensor as shown in FIG. 2 is not necessary. ) The oscillator that receives the reference signal generates a sine wave output ((C) in the same figure), and this sine wave output is stored in the ROM 53 as a phase controller for the corresponding rotational order component according to the engine speed.
11flt is read out, processed and output from the speaker (same figure (d)
)) enables more accurate phase and sound pressure control.
nl can be performed.

When forming a map of the ROM 53 used here, T
Instead of DC, the sensor output waveform (a) is used as the engine reference timing pulse (b), and the phase and sound pressure of the sine wave output waveform (C) are processed in the same way as in the case of Fig. 2 (engine temperature is not required). The control amount for generating d) may be experimentally measured.

FIG. 7 shows the case where the ignition sensor 80 is used and the case where the fixed reference point (T
DC), and the shaded area indicates that as the temperature rises, the volume reduction decreases.

If the ignition sensor is used in this way, control that takes into account at least the transmission characteristics of the engine mount system will suffice.

〔Effect of the invention〕

As described above, the vehicle interior noise reduction device according to the present invention uses a plurality of FA generators corresponding to the rotational order components caused by engine explosion, and detects the rotational order components to be controlled based on the engine rotational speed. The sine wave output from the corresponding oscillator is synchronized with the engine rotation, and each rotational order component is processed by the phase control amount and sound pressure control amount stored in advance to reduce cabin noise. , it is possible to reduce not only the muffled engine noise but also all other vehicle interior noise caused by engine rotation.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the low σ friend device for vehicle interior noise according to the present invention. FIG. 2 is a block diagram showing the controller in particular functionally in the embodiment of the present invention. FIG. 3 is a block diagram specifically showing the functionality of the controller in another embodiment; FIG. 4 is a block diagram specifically showing the functionality of the controller in yet another embodiment; FIG. A diagram showing the arrangement of the sensors, Figure 6 is a waveform diagram when the output pulse of the ignition sensor is used as the reference timing, Figure 7 is a graph diagram showing the effect when using the ignition sensor, and Figure 8 is: FIG. 9 is a three-dimensional graph diagram showing the sub-door target area at engine speed in the present invention. FIG. 9 is a waveform diagram for explaining changes in ignition timing when engine temperature changes. In FIG. 1, 1 is a car, 2 is an engine, 3 is a crank angle sensor, 5 is a controller, and 6° to 6. 1 is an oscillator, 7 is an amplifier, and 8 is a speaker. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A means for detecting a rotational order component due to an engine explosion, a plurality of oscillators that are provided corresponding to the rotational order component and generate a sine wave output, and a predetermined rotational order corresponding to the engine rotational speed detected by the detection means. control means for synchronizing a sine wave output of a component oscillator with the engine rotation and processing the sine wave output using a pre-stored phase control amount and sound pressure control amount for the predetermined rotational order component;
A vehicle interior noise reduction device comprising: an amplifier that amplifies the output of the control means to drive a speaker.