JPH0443806A - Silencing device for intake exhaust system - Google Patents

Abstract

PURPOSE:To reduce exhaust noise of low frequency with low cost and high efficiency by making the phase of sound pressure waveform input to the resonance chamber of a resonator reverse phase against the standing wave in the resonance chamber and specifying the input level thereof. CONSTITUTION:A standing wave mode in an intake and exhaust system is exactly decided from engine rotation pulse, intake air flow, and exhaust gas temperature in the condition of no input from a speaker 11 into a resonance chamber 9. The phase relation between the basic order component of engine rotation pulse and the sound pressure in the resonance chamber 9 is decided by utilizing this mode, so that the sound pressure waveform input from the speaker 11 into the resonance chamber is in reverse phase against the sound pressure in the resonance chamber 9. Further, input amplitude is set zero at silencing frequency of a resonator 10, and the level is elevated as it goes away from the silencing frequency. In this way, pulsation of intake air and exhaust gas can be cancelled with low cost and small force.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an intake/exhaust silencing device, and in particular to an intake/exhaust silencing device that reduces low-frequency intake/exhaust noise, which is a factor that worsens the muffled noise in the interior of an automobile. This invention relates to an exhaust silencer.

Conventional technology Recently, an intake/exhaust silencing device has been proposed that superimposes an output pulsation of the opposite phase to the intake/exhaust pulsation propagating through the intake/exhaust passages of the engine, thereby muffling the intake/exhaust noise. has been done.

An example of such an intake/exhaust silencing device is the one shown in Japanese Patent Laid-Open No. 62-48910. This includes a first pulsation detector that is provided in the exhaust passage of the engine and detects exhaust pulsation in the exhaust passage, and a pulsation detector that is provided downstream of the first pulsation detector to detect the pulsation in the exhaust passage. a pulsation generator that outputs pulsation, and a second pulsation generator that is provided at or near the downstream side of the superimposition point of the output pulsation from the pulsation generator and the exhaust pulsation that propagates in the exhaust passage, and that detects the pulsation in the exhaust passage. a pulsation detector; and an adaptive control means for receiving signals from the first pulsation detector and the second pulsation detector and outputting an adaptively optimized signal to the pulsation generator. is muted.

There is also one shown in Japanese Unexamined Patent Publication No. 57-96239. This is achieved by installing a diaphragm in a resonance chamber provided in the exhaust muffler and vibrating the diaphragm so as to produce a sound with the same amplitude and opposite phase as the exhaust pulsation sound that reaches the resonance chamber. It muffles the sound inside the resonant chamber.

Problems to be Solved by the Invention However, among such conventional intake/exhaust silencing devices, the one disclosed in Japanese Patent Application Laid-Open No. 62-4891.0 is attached to an exhaust pipe as an exhaust pulsation detector. Since it is generally a water-cooled pressure detector, it is expensive (approximately 200,000 yen per piece), and there is also the problem that the water-cooling device causes an increase in overlap.

In addition, in the method disclosed in Japanese Patent Application Laid-open No. 57-96239, in order to muffle sound by generating a sound with the same amplitude as the exhaust pulsation reaching the resonance chamber, it is necessary to vibrate with the same power as the exhaust pulsation. Since the plate must be vibrated and a considerable amount of power is required, a high output unit must be installed.

Another problem was that it was difficult to take into account the reflection of pressure waves.

The present invention was made in view of these conventional problems, and aims to provide an intake/exhaust noise muffling device that is inexpensive and capable of canceling intake/exhaust pulsations with small force. There is.

Means for Solving the Problems Therefore, the present invention provides an intake/exhaust noise silencing device that reduces intake/exhaust noise by inputting sound waves into the resonance chamber of a resonator.
Sound in the resonance chamber is generated using the standing wave mode in the intake/exhaust system, which is uniquely determined by the engine rotation pulse, intake air flow rate, and intake or exhaust gas temperature in the absence of sound wave input into the resonance chamber. The phase relationship between the basic order component of the engine rotation pulse and the sound pressure in the resonance chamber is determined so that the phase is opposite to the pressure waveform, and the input amplitude is zeroed at the resonator's silencing frequency and A map that gradually increases toward the frequency side is stored in advance, and the phase and amplitude of the waveform input into the resonance chamber are determined by detecting the engine rotation pulse, intake air flow rate, and intake or exhaust gas temperature. I tried to decide.

The phase of the sound pressure waveform input to the resonance chamber of the working resonator is opposite to the standing wave within the resonance chamber.

Further, the input level is zero at the silencing frequency of the resonator, and gradually increases toward the higher and lower frequency sides of the silencing frequency.

Therefore, the silencing frequency of the resonator can be changed, and the silencing effect can be maximized.

EXAMPLES The present invention will be explained below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention.

First, the configuration will be explained. Engine 1 has exhaust manifold 1'
Furthermore, a front tube 3 is connected to the exhaust manifold 2.

A catalyst 4, a center tube 5, a main muffler 6, and a tail tube 7 are attached after the front tube 3.

A resonator 10 consisting of a neck portion 8 and a resonance chamber 9 is disposed in the center tube 5, and a speaker 11 is disposed on the bottom surface of the resonance chamber 9.

'if knee, m air manifold 2, center tube 5,
Gas temperature sensor] 2, 13.14 is attached to the resonance chamber 9 of the resonator 10, respectively, and the outputs T, , T, T of these gas temperature sensor 12, 13.14 are respectively attached.
3 is input to the control unit 17. Furthermore, an ignition pulse sensor w15 and an intake air flow rate sensor 16 are attached to the engine 1, and these sensors 15, 16
Output N.

Q is also input to the control unit 17.

FIG. 2 shows details of the control unit 17. The control unit 17 includes a calculation section 18, a ROM 19. It is composed of a power amplifier 20 and the like, and includes the gas temperature sensors 12, 13, and the like described above.
Signal from 14 TI+T! +T3, engine rotation pulse N1 from ignition pulse sensor 15 When intake air flow rate Q from intake air flow rate sensor 16 is input, the calculation unit calculates the optimum level and phase based on the data map stored in advance in ROM 19. Calculated with 18, power amplifier 2
0 and is output to the speaker 11.

Here, the map utilizes the standing wave mode in the intake/exhaust system that is uniquely determined by the engine rotation pulse, intake air flow rate, and exhaust gas temperature in a state where there is no input from the speaker 11 into the resonance chamber 9. The basic order component of the engine rotation pulse and the phase of the sound pressure in the resonance chamber 9 are adjusted so that the sound pressure waveform input from the speaker 11 to the resonance chamber 9 has an opposite phase to the sound pressure in the resonance chamber 9. determine and remember relationships;
Furthermore, the input amplitude is 0 at the silencing frequency of the resonator 10,
The level is stored so as to increase as the distance from the silencing frequency increases.

Next, the operation will be explained with reference to FIGS. 3 and 4. 1st
When there is no load on the exhaust system shown in the figure, that is, when there is no input signal from the speaker 11 to the resonator 10,
Figure 3 shows the low frequency sound pressure mode.

Figure 3(a) shows the resonance sound pressure mode of the engine rotation speed second order.
FIG. 3(C) shows the resonance sound pressure mode at the third-order engine rotational speed, and FIG. 3(b) shows the sound pressure mode near the silencing frequency of the resonator 10.

The solid line in FIG. 4 shows the discharge sound characteristics of the exhaust system. The sound pressure modes at engine speeds a, b, and c RPM are shown in FIG. 3 (a) and (b), respectively.

It corresponds to (C).

As can be seen from Fig. 3, on the frequency side lower than the silencing frequency of the resonator 10 (Fig. 3 (a)), the sound pressure immediately after the engine 1 (e in the figure) and the sound pressure in the resonance chamber 10 (θ in the figure) ), and on the high frequency side (Figure 3 (C)), the same phase (
In the figure, both are e).

Therefore, when generating standing waves as shown in FIGS. 3(a) and (c), in FIG. 4, engine rotational speed a - b
In between, a signal in phase with the basic order waveform obtained from the engine ignition pulse is input to the speaker 11, and a signal in opposite phase is input in between engine speed b and c. The input level gradually decreases in the engine speed range a to b, and the input level decreases as the engine speed increases.
and gradually increase it in the range b - c.

By controlling in this way, the silencing frequency of the resonator 10 can be changed, so as shown by the dotted line in FIG. can be pulled out.

The calculation of the input signal to the speaker 11 is performed by the control unit 17 shown in FIG. That is, the control unit y) 17
The calculation unit 18 provided at (T I+ T t
, Ts), the input waveform is determined by a map stored in the ROM 19 in advance, and is output to the speaker 11 through the power amplifier 20.

Here, even if the engine load increases, the phase difference between immediately after the engine 1 and the resonance chamber 9 can be uniquely determined by using the standing waves generated from the information on the intake air flow rate and exhaust temperature. By creating a map in advance and using that map, the optimum input signal to the speaker 11 can always be obtained.

In addition, in the embodiment described above, the resonator 10
On the lower frequency side than the silencing frequency (on the resonant mote side due to the engine rotation speed component), we try to input a waveform with the same phase as the fundamental order component of the ignition pulse, but depending on the configuration of the exhaust system and the attempt to mute the noise. This relationship will change if the frequencies used differ, but the basic idea remains the same, so the present invention can be applied to all cases.

FIG. 5 shows a second embodiment of the invention. In this embodiment, the structure of the resonator 10 in the first embodiment is changed, and a resonance chamber 22 is provided so as to surround the neck portion 21 connected to the center tube 5, and a speaker 23 is provided in a part of the resonance chamber 22. is attached.

According to this embodiment, the same effects as the first embodiment can be obtained, and there is no need to provide a speaker to face the sound that enters through the neck as in the first embodiment, and resonance is achieved. Since the speaker 23 can be placed anywhere within the chamber 22, the position of the speaker 23 can be set freely, and the effect of increasing the degree of freedom in manufacturing and shaping can be obtained.

FIG. 6 shows a third embodiment of the invention. In this embodiment, the present invention is applied to an intake system.

An intake manifold 30 is attached to the engine 1,
An intake collector 29 is connected to the intake manifold 30. Further, an intake pipe 27 is attached to the intake collector 29, and an air cleaner 25 and an intake duct 24 are further connected thereto.

A throttle 28 and an intake air flow rate sensor (air flow meter) 26 are attached to the intake pipe 27 to constitute an intake system.

A resonator 10 consisting of a neck portion 8 and a resonance chamber 9 is disposed in the intake pipe 27, and a speaker 11 is provided at the bottom of the resonance chamber.
is installed.

Signals from the gas temperature sensor 31 installed in the intake duct 24, the engine ignition pulse sensor 15 installed in the engine 1, and the intake air flow rate sensor 26 installed in the intake pipe 27 are output to the control unit 17 as needed. 1
The calculation unit 18 provided in the ROM 1
An input signal to the speaker 11 is determined based on the map stored in the power amplifier 9, and the input signal is outputted to the speaker 11 through a power amplifier 21 for control.

According to this embodiment, basically the same effects as those of the first embodiment can be obtained, and in the case of an intake system, the temperature distribution in the intake system is approximately constant, so the gas temperature sensor 31 Only one is enough.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, there is no need to use expensive sensors to directly measure the pulsating pressure in the intake and exhaust pipes. The input waveform can be determined.

Further, since the silencing effect of the resonator is effectively utilized to expand the frequency range in which the silencing effect of the resonator can be obtained, the input to the resonator can be small, and there is no need to provide a high-output speaker.

Therefore, it is possible to reduce low-frequency exhaust noise, which is a problem in the interior of the vehicle, at low cost and efficiently.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention, FIG. 2 is an enlarged configuration diagram showing a control unit, FIG. 3(a),
(b) and (c) are diagrams showing the sound pressure mode of the exhaust system, Figure 3 (a) is a resonance sound pressure mode diagram of the second-order engine rotation speed, and Figure 3 (b) is a diagram showing the resonance sound pressure mode around the resonator's silencing frequency. Fig. 3(c) is a resonance sound pressure mode diagram of the third order of the engine rotation speed, Fig. 4 is a characteristic diagram of the fundamental order component of the engine rotation speed of exhaust discharge sound, and Fig. 5 is a diagram of the resonance sound pressure mode of the engine rotation speed of the third order. FIG. 6 is an overall configuration diagram showing the second embodiment, and FIG. 6 is an overall configuration diagram showing the third embodiment of the present invention. 1...engine, 5..., center tube, 8...
Neck, 9 Resonance chamber, 10... Resonator, 11... Speaker,! 2.13.14...-Gas temperature sensor, 15 m/n ignition pulse sensor, 16 Intake air flow rate sensor,
17・Control unit, 18...Calculation unit, 19...R
OM, 21 ・Neck, 22 ・Resonance chamber, 23 Speaker, 2
6. Intake air flow rate sensor, 27. Intake pipe, 31-. Gas temperature sensor.

Claims (1)

[Claims] (1) In an intake/exhaust silencing device that reduces intake/exhaust noise by inputting sound waves into the resonance chamber of a resonator, the engine rotation pulse, intake air flow rate, and intake or Utilizing the standing wave mode within the intake and exhaust system, which is uniquely determined by the exhaust gas temperature,
The phase relationship between the basic order component of the engine rotation pulse and the sound pressure in the resonance chamber is determined so that the sound pressure waveform input to the resonance chamber is in reverse phase with respect to the sound pressure waveform in the resonance chamber. is zero at the silencing frequency of
A map that gradually increases toward the high frequency side and the low frequency side is stored in advance, and the engine rotation pulse, intake air flow rate,
and an intake/exhaust silencing device, which detects intake air or exhaust gas temperature and determines the phase and amplitude of a waveform input into a resonance chamber based on the map.