JP2767855B2 - Intake noise reduction device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake noise reduction device that reduces intake noise of an engine intake system.

[Related Art] One of the noises of an automobile is an intake noise of an engine.

Heretofore, in order to reduce the intake noise, a noise reduction device has been provided in the middle of the intake pipe.

However, in general, the attenuation characteristics of the silencer and the airflow resistance are in a reciprocal relationship, and a sufficient attenuation effect cannot be obtained.
Due to the problem that the amount of air sucked into the engine is reduced due to excessive passing air resistance and the output of the engine is reduced as a result, the intake sound generated at the intake port is eliminated recently. There are proposals such as "Vehicle intake sound silencer" (Japanese Utility Model Application Laid-Open No. 63-113759), which emits sound waves of different amplitudes and phases from speakers to reduce exhaust noise.

In other words, the proposal proposes a configuration in which the phase of the intake coarse density is detected by the engine speed sensor and the amplitude of the intake compression wave is detected by the error microphone, while the high frequency component of the error microphone that detects the amplitude of the intake compression wave is low-passed. The filter is configured to detect the averaged DC amplitude after being removed by a filter.

[Problems to be Solved by the Invention] However, strictly, the intake sound of the engine is obtained by synthesizing (adding) frequency components of n times the engine speed, so that the intake sound at the fundamental frequency (n = 1). Although it is possible to reduce the noise, it is difficult to reduce the intake sound at the n-th frequency, and it is also difficult to actually attach an error microphone sensitive to vibration to the engine. Was.

Means for Solving the Problems An object of the present invention is to solve the above problems, and a sound wave interferometer that radiates an interfering sound wave to an intake port, an oscillator that oscillates a sine wave synchronized with an engine speed, and Create a sine wave that is an integral multiple of the oscillating sine wave,
N controllers for adjusting the phase, a controller for determining the amplitude and phase of an integral multiple sine wave to be adjusted by each controller based on the memory data of the amplitude and phase corresponding to the engine speed; An adder for adding the output signals of the controllers and outputting the sum to the interferometer constitutes an intake noise reduction device.

[Operation] In this case, in correspondence with the n-th frequency of the intake wave,
Creates a sine wave that is an integral multiple of 1,2,3, ..., n-1, n times the fundamental frequency. The amplitude value and phase value of these n integral multiple sine waves correspond to the engine speed. Adjustment is made according to the memory data. The adder adds and combines the adjusted sine waves output from the adjuster, generates an interference sound wave having a waveform that interferes with the intake sound wave, and outputs the signal to the sound wave interferometer as a signal. Then, the sound wave interferometer emits an interference sound wave 180 ° out of phase with the intake wave toward the intake port.

Therefore, the interference sound wave radiated from the sound wave interferor and the suction sound wave generated at the suction port cancel each other, and the suction noise is greatly reduced.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, an intake pipe 2 attached to an engine 1
A sound wave interferometer 4 is attached to the intake port 3 side of.

In the embodiment, the sound wave interferometer 4 has a well-known speed, and a vibrating coil 5 surrounding the intake port 3 of the intake pipe 2.
And a highly water-resistant cone 6 that vibrates in response to the vibration of the vibration coil 5 and emits sound waves around the intake port 3 from downstream to upstream. A power amplifier 7 for adjusting an input signal level is attached to an input of the vibration coil 5. An engine speed sensor 9 for pulsating and detecting the engine speed is attached to the rotating shaft 8 of the engine 1. The output of the engine speed sensor 9 is connected to the inputs of a synchronous oscillator 10 and a controller 11, respectively. Outputs of the synchronous oscillator 10 are connected to inputs of a plurality of frequency adjusters 12. The output of the frequency controller 12 is a gain controller
The outputs of these gain adjusters 13 are connected to the inputs of each phase adjuster 14, respectively. Further, the output of each phase adjuster 14 is connected to one adder 17. The output of the adder 17 is connected to the input of the sound wave interferor 4 via the power amplifier 7.

By the way, the oscillator 10 is connected to the engine speed sensor 9.
Each of the frequency adjusters 12 generates a sine wave of an integral multiple of the reference frequency (1, 2, 3,..., N−1, n) so as to generate a sine wave with respect to the reference frequency (n = 1). So that the gain adjuster 13 adjusts the amplitude value of each integer multiple sine wave, and each phase adjuster 14 displaces the phase value of the integer multiple sine wave generated by each frequency adjuster 12. It is configured to be. In contrast, the controller 11 has a counter 15
The number of input pulses is counted to calculate the number of revolutions of the engine 1, and the amplitude value is obtained from the number-of-rotations-gain map (FIGS. 3 and 4) stored in the memory 16 as data. A phase value is obtained from a stored rotation speed-phase map (FIGS. 5 and 6), and the obtained amplitude value and phase value are input to the gain adjuster and phase adjuster 14. The adjusters 13 and 14 are configured to adjust the amplitude value and the phase value of the n integer-multiple sine waves based on a command from the controller.

In other words, a sine wave of an integral multiple of 1,2,3, ..., n-1, n times the fundamental frequency is created corresponding to the nth frequency of the intake wave, and the amplitude value of each created sine wave is generated. , And the phase value are adjusted based on the memory data corresponding to the engine speed so as to generate an integral multiple sine wave of the amplitude value and the phase value corresponding to the intake wave.

On the other hand, the adder 17 adds the adjusted sine wave,
It is configured to generate an interference sound wave having a waveform corresponding to the inspiratory wave. Here, in particular, the gain and phase that can eliminate the n-th frequency component of the actual intake wave are input to the rotation speed-gain map and the rotation speed-phase map. The gain and the phase are determined based on the actually measured values. In particular, as the phase, a value shifted from the actual nth-order frequency component by 180 ° is input.

 Next, the operation will be described.

When the engine 1 is driven, as shown in FIG. 2, the engine speed sensor 9 detects a pulse corresponding to the speed of the engine 1 and outputs the detected pulse to the oscillator 10 and the counter.
Enter in 16 respectively. The synchronous oscillator 10 has a reference frequency (n = 10) synchronized with the engine speed according to the input pulse.
The sine wave of 1) is oscillated, and the oscillated sine wave is input to each frequency adjuster 12. Each frequency adjuster 12 produces n integer multiple sine waves with respect to the fundamental frequency. In other words, each frequency adjuster 12 creates a sine wave that is an integral multiple of 1, 2, 3,..., N−1, n times the fundamental frequency in accordance with the n-th frequency of the intake wave. The generated integer multiple sine waves are input to each gain adjuster 13. At this time, the controller 11 calculates the number of revolutions of the engine 1 from the number of input pulses counted by the counter, and calculates the number of revolutions for each order from a map of the number of revolutions-gain (FIGS. 3 and 4) stored in advance in the memory 16 as data. From the rotational speed-phase map (FIGS. 5 and 6) stored in advance in the memory 16 as data, a value deviated from the actual intake wave by 180 ° for each order. Asked,
The gain adjuster 13 and the phase adjuster 14 are adjusted. This results in a sinusoidal wave 180 degrees out of phase with the intake noise (out of phase). Thereafter, the adder 17 adds and combines the adjusted integer sine waves output from the phase adjuster 14 to form an interference sound wave having a waveform that interferes with the intake sound wave and inputs the interference sound wave to the power amplifier 7. The power amplifier 7 adjusts the level of the input interfering sound wave and inputs it to the sound wave interferometer 4.
Then, the sound wave interferor 4 radiates an interference sound wave whose phase is shifted by 180 ° with respect to the intake wave toward the intake port 3. As a result, the interference sound wave emitted from the sound wave interferometer 4 and the suction sound wave generated at the suction port 3 mutually cancel each other, and the suction noise is reduced.

Each of the above maps is uniquely determined by the characteristics of the engine 1 and the intake pipe 2.

[Effects of the Invention] As is apparent from the above description, according to the present invention, it is possible to reduce the intake sound at the n-order frequency, and to provide an excellent effect that an error microphone is not required.

[Brief description of the drawings]

FIG. 1 is a schematic structural diagram showing a preferred embodiment of the present invention, FIG. 2 is a flowchart showing an example of control of a controller, and FIGS. 3 to 6 are diagrams showing examples of maps. In the figure, 3 is an intake port, 4 is a sound wave interferometer, 9 is an engine speed sensor, 10 is an oscillator, 11 is a controller, and 12, 13, and 14 are regulators.

Claims (1)

(57) [Claims] 1. A sound wave interferometer for radiating an interfering sound wave to an intake port, an oscillator for oscillating a sine wave synchronized with the engine speed, and a sine wave that is an integral multiple of the oscillating sine wave is produced. N adjusters for adjusting the amplitude and phase of
A controller for determining the amplitude and phase of the integral multiple sine wave to be adjusted by each of the controllers based on the memory data of the amplitude and phase corresponding to the engine speed; An intake noise reduction device, comprising: an adder for outputting to an interferometer.