KR20020042357A - Exhaust Noises Reduction Apparatus Using Open-Loop Control Method - Google Patents

Abstract

PURPOSE: An active open control reduction apparatus of exhaust noise is provided to reduce exhaust noise by estimating exhaust noise with detecting the state of an engine, and to cut down expenses and improve stability by removing a noise detecting unit. CONSTITUTION: An active control device for reducing exhaust noise is composed of an engine state detecting unit checking an engine(20) of a vehicle; a control unit outputting a control signal based on the engine state from the engine state detecting unit for reducing exhaust noise; and a damping signal generating unit outputting an exhaust noise damping signal according to the control signal from the control unit. The engine state detecting unit has a throttle position sensor(22), a crank angle sensor(24), and a top dead center sensor(26). The control unit consists of an engine control unit(30), and the exhaust noise damping signal generating unit has an amplifier(40) and an actuator(50). Exhaust noise is reduced with estimating exhaust noise by detecting the engine state of the vehicle.

Description

Exhaust Noises Reduction Apparatus Using Open-Loop Control Method}

The present invention relates to an exhaust noise reduction device, and more particularly, to an exhaust noise reduction device by an open active control method which predicts exhaust noise and controls the active noise control method.

BACKGROUND ART Exhaust noise reduction by a geometry is generally used as an exhaust noise reduction system employed in vehicles and the like. As shown in FIG. 1, the muffler 14 reduces noise generated through the exhaust manifold 12.

Another exhaust noise reduction method is Active Noise Control, which relies on feedback control using input and error microphones or feedback control using only error microphones. Most of these conventional exhaust noise reduction methods are based on closed loop control.

When the exhaust noise is reduced by using the muffler, the expansion pipe, or the like, there is a problem in that an output loss occurs due to an increase in the exhaust pressure, and there is a problem in that control is not possible except for a predetermined frequency.

In addition, according to the active noise control method by the closed loop control method, not only an additional sensing device such as a microphone is required, but also there is a problem that the control system itself emits instability when there is an inaccuracy of the control algorithm.

Accordingly, the present invention has been made to solve the above-mentioned problems in the prior art, by detecting an engine state, predicting the exhaust noise, and adopting an active noise control method that attenuates the exhaust noise, thereby detecting the same noise as a conventional microphone. It is an object of the present invention to provide an exhaust noise reduction device by an open active control method that can reduce costs by eliminating wealth and promote system stability.

In order to achieve the above object, the exhaust noise reduction device according to the open active control method according to the present invention includes an engine state sensing means for sensing an engine state of a vehicle, and an engine state detected from the engine state sensing means. And control means for calculating and outputting a control signal for reducing exhaust noise, and exhaust noise attenuation signal generating means for generating an exhaust noise attenuation signal for attenuating exhaust noise in accordance with the control signal of the control means.

According to the present invention configured as described above, it is possible to detect the state of the engine, predict the exhaust noise, and reduce the exhaust noise.

1 is a schematic configuration diagram of an exhaust noise reduction device of a conventional vehicle;

2 is a view for explaining the principle of the exhaust noise reduction system according to the present invention;

3 is a schematic configuration diagram of an exhaust noise reduction device according to an open active control method according to the present invention;

4 is a circuit block diagram of an exhaust noise reduction device according to an open active control method according to the present invention;

5 is a flowchart illustrating a control flow of the exhaust noise reduction device according to the open active control method according to the present invention.

<Description of the symbols for the main parts of the drawings>

10 exhaust system 12 exhaust manifold

14: muffler 16: exhaust temperature sensor

20: engine 22: throttle position sensor

24: crank angle sensor 26: top dead center position sensor

30: engine control unit 40: amplifier

50: actuator (speaker)

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the exhaust noise reduction device according to the open active control method according to the present invention.

Exhaust noise generated from an exhaust system used in a vehicle or the like should be considered by the influence of temperature and the influence of the exhaust velocity, but the occurrence of noise can be predicted since the occurrence of the noise itself has a repeatability (periodicity).

Thus, by predicting the primary noise generated in the exhaust system (a in FIG. 2) and generating counter noise of the same magnitude (b in FIG. 2) having an opposite phase to the predicted noise, FIG. The exhaust noise can be canceled as shown.

That is, in the case of vehicle exhaust noise, the explosion order component is dominant, and thus it is predictable because it occurs periodically in a linear relationship with the engine speed. Therefore, when the vehicle is initially developed, it is possible to control the noise through the noise attenuating actuator with a slight correction of the factors that can provide the noise deformation factor as a value mapped from the test data of the engine. .

3 is a schematic configuration diagram of a device for reducing exhaust noise by an open active control method according to the present invention. Exhaust noise reduction device of the present invention is the engine state detection means for detecting the state of the engine, the control means for calculating and outputting a control signal for reducing the exhaust noise based on the engine state detected from the engine state detection means; And exhaust noise attenuation signal generation means for generating an exhaust noise attenuation signal for attenuating exhaust noise in accordance with the control signal of the control means.

The engine state detecting means is for detecting the rotational speed (RPM) of the engine 20, the load of the engine, the crank angle, the position of the top dead center, etc. The control means is the rotational speed (RPM), the load of the engine, Engine control unit 30 for outputting a control signal for generating attenuation noise for attenuating the original noise generated in the exhaust system 10 by using the position of the crank angle, top dead center, etc., the exhaust The noise attenuation signal generating means may include an amplifier 40 for amplifying a control signal of the engine control unit 30 and an actuator 50 for outputting an exhaust noise canceling signal according to an output signal of the amplifier 40. .

As shown in FIG. 4, the engine state detecting means detects the state of the engine 20, and has a throttle position sensor 22, a crank angle sensor 24, and a top dead center position. It comprises a sensor (Top Dead Center sensor) 26. Here, the signals from the sensors 22, 24 and 26 are necessary to determine the magnitude, frequency and phase of the signal required for driving the actuator 50.

In addition, the engine condition detecting means further comprises an exhaust temperature detecting sensor 16 for detecting the temperature of the exhaust system 10.

The actuator 50 is preferably configured to include a speaker for outputting the noise attenuation sound having the same frequency and magnitude as the noise generated in the exhaust system 10 and having an opposite phase to the exhaust system 10 side. .

The engine control unit 30 has a sound pressure and phase information of noise according to the engine speed already input at the time of manufacture, and considering the change in sound speed according to exhaust temperature, the volume of noise attenuation to be generated. , The frequency and the phase are determined and the control signal is output to the amplifier 40.

On the other hand, the engine state detecting means employs a cam position sensor without using the top dead center position sensor 26 to calculate the top dead center position according to the detection signal of the cam position sensor and the detection signal of the crank angle sensor 24. You may comprise.

Next, the control flow of the exhaust noise reduction device by the open active control method according to the present invention configured as described above will be described in detail with reference to FIG.

First, the engine control unit 10 determines whether the ignition switch is turned on by the user (step S10), and when the ignition switch is turned on, the respective sensors 22, 24, and 26 are turned on. Wait for an input signal from (16) (step S12).

Thereafter, the engine control unit 30 determines whether the detection signal TPS input from the throttle position sensor 22 is greater than zero (step S14). If it is determined that the detection signal TPS is not greater than zero, the control of the engine control unit 30 returns to the above-described step S12.

On the other hand, if it is determined in step S14 that the detection signal TPS is greater than zero, the engine control unit 30 generates a control signal which is mapped and stored in advance corresponding to the current engine RPM signal (step S14). S16). The control signal p (t) = a × f (t), where f (t) is pre-mapped data corresponding to the current PRM signal.

Thereafter, the engine control unit 30 calculates a factor a according to the throttle valve opening degree value detected and input from the throttle position sensor 22 (step S18). That is, in step S18, the value of a is determined at p (t) = a x f (t).

Subsequently, the engine control unit 30 analyzes the detection signal from the top dead center position sensor 26, the detection signal from the crank angle sensor 24, and the detection signal from the exhaust temperature sensor 16 to determine p (t−). t1 is determined at t1) = a x f (t-t1) (step S20), and a control signal for attenuating noise to be generated next is generated and output (step S22).

As the control signal from the engine control unit 30 is amplified by the amplifier 40 and then input to the speaker as the actuator 50, the speaker has the same magnitude and frequency as the exhaust noise of the exhaust system and is reversed in phase. Phosphorous noise attenuation sound is output to the exhaust system 10 side (steps S24 to S26).

That is, the engine control unit 30 predicts the next exhaust noise (that is, the exhaust noise at the time t-t1) from the current engine state (that is, the engine state at the time t) as described above, and generates a control signal. By generating and outputting the control, the noise attenuation sound is output through the actuator 50.

In the course of this processing routine, the engine control unit 30 judges whether the ignition switch is turned off by the user, and if the ignition switch remains on, proceeds to step S12 described above, while the ignition switch is turned off. When the exhaust noise attenuation control processing routine ends.

On the other hand, in the above specific embodiment has been described simply to reduce the exhaust noise, the present invention can change the sound quality by adjusting the characteristics of the noise control in consideration of the influence of the exhaust noise on the room sound as well as the exhaust noise. It has the advantage that it is. That is, by controlling the characteristics of the exhaust noise depending on the mode desired by the driver can provide a sporty driving feeling as well as quiet driving. This is done by adjusting the sound pressure control size to enable the selection of sporty driving or quiet driving through the increase and decrease of the booming noise. In this case, a mode selector for selecting a sound pressure level may be further provided by the user, and the engine control unit 30 may control the sound pressure control size based on data stored in advance according to the selection of the mode selector. .

On the other hand, the present invention is not limited to the above-described specific embodiments, but can be modified and modified in various ways without departing from the gist of the present invention. It should be noted that such variations or modifications are included in the scope of the present invention as long as the features of the present invention are used.

As described above, according to the present invention, by adopting an active noise control method that detects the state of the engine, predicts the exhaust noise, and attenuates the exhaust noise, the system reduces the cost by eliminating the noise sensing unit such as the existing microphone. Stability can be achieved.

In addition, according to the present invention, the sound quality can be changed by adjusting the characteristics of the noise control in consideration of the effect of the exhaust noise on the room sound as well as the reduction of the exhaust noise.

Claims (9)

An apparatus for attenuating exhaust noise generated in an exhaust system of a vehicle, Engine state detecting means for detecting an engine state of the vehicle; Control means for calculating and outputting a control signal for reducing exhaust noise based on the engine state detected by the engine state detecting means; And exhaust noise attenuation signal generating means for generating an exhaust noise attenuation signal for attenuating exhaust noise in accordance with a control signal of said control means. The exhaust noise reduction apparatus according to claim 1, wherein the engine state detecting unit detects the rotation speed of the engine, the load of the engine, the crank position, and the top dead center position. The method of claim 2, wherein the control means outputs a control signal for generating attenuation noise for attenuating the original noise generated in the exhaust system by using the rotation speed, the load of the engine, the crank position, the top dead center position. Exhaust noise reduction device according to an open active control method, characterized in that the engine control unit. The method of claim 3, wherein the exhaust noise attenuation signal generating means comprises an amplifier for amplifying a control signal of the engine control unit and an actuator for outputting an exhaust noise cancel signal in accordance with an output signal of the amplifier. Exhaust noise reduction device by open active control system. 5. The engine condition detecting means according to claim 4, wherein the engine state detecting means comprises a sensor for detecting the position of the throttle valve, a sensor for detecting the opening degree of the crank valve, and a sensor for detecting the top dead center position of the piston. Exhaust noise reduction device by open active control system. 6. The exhaust noise reducing device according to claim 5, wherein the engine state detecting means further comprises an exhaust temperature detecting sensor for detecting a temperature of the exhaust system. 7. The open active control method according to claim 6, wherein the actuator comprises a speaker for outputting noise attenuation sound having the same frequency and magnitude as the exhaust noise generated in the exhaust system and having opposite phases. Exhaust noise reduction device. The method of claim 7, wherein the engine control unit has phase information on the sound pressure of the exhaust noise according to the engine speed stored in advance, and considering the change in sound speed according to the exhaust temperature, the magnitude of the noise attenuation to be generated, Exhaust noise reduction device according to the open active control method, characterized in that for determining the frequency and phase to generate a control signal and output to the amplifier. 9. The apparatus of claim 3, further comprising a mode selector for selecting a sound pressure level by a user, wherein the engine control unit is configured by the pre-stored data according to the selection of the mode selector. Exhaust noise reduction device according to an open active control method, characterized in that for controlling.