RU47981U1 - ACTIVE MOTOR NOISE SUPPRESSION SYSTEM - Google Patents

Abstract

The utility model relates to the automotive industry, and in particular to systems for reducing noise from internal combustion engines. The technical result consists in eliminating the need for preliminary tuning of the system, which now has the ability to self-adjust while maintaining a low system cost. This result is achieved by the fact that the structure of the active noise suppression system of an automobile engine, comprising a crankshaft position sensor mounted on the engine, an electronic sound field compensation unit and an acoustic unit (loudspeaker), includes a microphone installed in the area of the car, the noise level of which must be reduced , and noise reduction signal calculations are automatically performed by an 8-bit microcontroller with RISC architecture with a built-in ADC of the AVR family.

Description

The utility model relates to the automotive industry, and in particular to systems for reducing noise from internal combustion engines.

The engine during operation creates noise at frequencies that are multiples of the frequency of rotation of its crankshaft. Sources of noise are engine intake and exhaust systems and its own vibration.

A phenomenon has long been known in the art when sound pressure waves, equal in magnitude and opposite in phase, are mutually destroyed. So, the active sound cancellation system is known (Patent of the Russian Federation for utility model No. 38027, F 02 B 77/13, 60 60 13/08, 2004), containing a crankshaft position sensor mounted on the engine, an electronic sound field compensation unit, speaker system and electronic fuel control unit. This system, if properly tuned to the control points of a specific passenger compartment, compiles the corresponding compensation harmonic table and introduces it into the memory of the electronic sound field compensation unit, allows you to create a signal opposite to the phase of the second reverse harmonic of the engine, which, when combined with the total engine noise, provides a slight reduction in its level .

The disadvantage of this system is the need for its rather laborious preliminary tuning and preliminary compilation of a table of compensation harmonics for each specific car interior, since they all have their own characteristics of the propagation of the sound field.

The technical result achieved by the claimed solution is to eliminate the need for preliminary configuration of the system, since now it has the ability to self-adjust. At the same time, the relatively low cost of the system is saved.

This result is achieved by the fact that the active noise suppression system, which includes a crankshaft position sensor mounted on the engine, an electronic sound field compensation unit and an acoustic unit, includes a microphone installed in the area of the car where the noise level is to be reduced. In the electronic unit for compensating the sound field, the microcontroller uses an 8-bit microcontroller with RISC architecture with a built-in analog-to-digital converter (ADC) of the AVR family. This reduces the cost of the system.

The system can be used to reduce internal noise in the passenger compartment and to reduce noise in its engine compartment.

The inventive system is illustrated by a diagram on which are indicated:

1 - microphone;

2 - crankshaft position sensor;

3 - electronic block compensation of the sound field;

4 - acoustic unit.

To ensure noise reduction at the driver’s place, a loudspeaker (acoustic unit 4) is installed in the passenger compartment between the engine (noise source) and the driver. Microphone 1 is preferably installed near the driver’s head.

The active noise reduction system of an automobile engine operates as follows:

After installing the system on the car, the calibration program starts. The program saves the dependence of the amplitude and phase of the sound on frequency obtained during calibration in the memory built into the microcontroller (EEPROM).

During operation of the system, the signal from the microphone 1 and the crankshaft position sensor 2 are sent to the microcontroller. The microcontroller digitizes the signal from the microphone 1 and calculates, using the synchronizing signal of the sensor 2, the amplitude and phase of the reverse harmonics of the engine in the total noise. Further, according to the data from the memory (EEPROM), it calculates the blanking signal and synthesizes it. The damping signal from the electronic unit 3 is fed to the acoustic unit 4, the sound vibrations of which, combined with the sound waves of the engine reverse harmonics located in antiphase, reduce the level of general noise.

Claims (1)

An active engine noise reduction system comprising a crankshaft position sensor mounted on the engine, an electronic sound field compensation unit and an acoustic unit, characterized in that a microphone is connected to the electronic sound field compensation unit in an area in which it is necessary to reduce the overall noise level and the electronic unit for compensating the sound field uses an 8-bit microcontroller with RISC architecture with a built-in ADC of the AVR family.