JP2005330894A - Variable frequency noise reduction system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable frequency noise reduction system capable of giving occupants including a driver natural feeling of driving an automobile. <P>SOLUTION: This variable frequency noise reduction system selectively silencing a desired noise frequency of engine intake system noise generated and changed according to a vehicular engine rotation speed by an engine rotation speed detection device, a computing process device and a variable frequency resonance type resonator device. Ratio of low frequency component in relation to whole noise level is lower as engine rotation speed is high by using resonance or antiresonance which are characteristics of the variable frequency resonance type resonator device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention selectively selects a desired noise frequency according to the rotational speed of an engine intake system noise generated and changed according to the rotational speed of a vehicle engine by means of an engine rotational speed detection device, an arithmetic processing device, and a variable frequency resonance type resonator device. The present invention relates to a variable frequency silencing system (device) for silencing sound.

  A resonance muffler called a resonator is mounted on the intake system of an automobile engine. Resonators include a fixed resonator in which the silencing frequency does not change, and a variable frequency resonator (for example, Patent Documents 1 to 12) that varies the silencing frequency in accordance with the engine speed and the vehicle speed. It is a reduction.

However, since the purpose of conventional resonators is to reduce intake noise with a focus on quietness (below the target noise level), in general, when the noise level is reduced at any engine speed, the speed Is set to lower the frequency component with the highest level. As a result, although quietness is felt for the passengers including the driver, the sound may become lower or undulate (become higher or lower) as the engine speed increases. . FIG. 10 is a graph showing a ratio (ratio value) of a low frequency (in this case, greater than 0 Hz and less than or equal to 300 Hz) in the entire noise level with respect to the engine rotation speed for an intake sound characteristic of a certain automobile. It is a graph which shows the case where it waves as a rotation speed becomes high.
For this reason, passengers including the driver may feel unnaturalness in driving feeling and sound pitch (frequency component).
JP 2001-50127 A JP 2001-123902 A JP 2000-154725 A JP 2000-337219 A JP-A-10-102621 JP-A-10-153152 Japanese Patent Laid-Open No. 7-259671 JP-A-7-293377 Japanese Patent Laid-Open No. 10-299451 JP-A-8-158964 JP-A-8-109857 JP-A-8-82260

The problem to be solved by the present invention is to make an occupant including a driver feel unnaturalness in driving feeling and sound pitch.
An object of the present invention is to provide a variable frequency silencing system capable of giving a natural feeling of driving an automobile to passengers including a driver.

The present invention for achieving the above object is as follows.
(1) A desired noise frequency is selectively silenced according to the number of revolutions of the engine intake system noise generated and changed according to the engine speed of the vehicle by means of an engine speed detection device, an arithmetic processing unit, and a variable frequency resonance type resonator device. A variable frequency silencer system,
A variable frequency silencing system that utilizes resonance or anti-resonance, which is a characteristic of the variable frequency resonance type resonator device, such that the higher the engine speed, the lower the ratio of the lower frequency to the overall noise level.

  In the variable frequency silencing system of (1) above, the lower the ratio of the lower frequency to the overall noise level the lower the engine speed, so the lower the engine speed, the higher the higher the sound. By doing so, it is possible to give the passengers including the driver a natural feeling of driving a car.

  As shown in FIGS. 1 and 2, the variable frequency silencing system (apparatus) 10 according to the embodiment of the present invention calculates engine intake system noise generated and changed in accordance with the engine speed of the vehicle and an arithmetic process with the engine speed detector 20. This is a variable frequency silencing system that selectively silences a desired noise frequency according to the engine speed by the device 30 and the variable frequency resonance type resonator device 40.

  The variable frequency resonance type resonator device 40 includes a frequency variable resonator 41 that includes a resonance unit 42, a fixed neck wall 43, and a frequency fixed resonator 44 that is movable with respect to the fixed neck wall 43, and a drive actuator that drives the frequency fixed resonator 44 ( Motor) 45 and a rotation angle detection unit 46 that detects the rotation angle of the frequency fixed resonator 44.

The resonance part 42 is attached in the middle of the pipe of the engine intake system. As shown in FIG. 2, the resonance unit 42 has a resonance chamber inside. An opening 42a connected to the engine intake system is formed in one wall of the resonance portion 42. The opening 42a has a semicircular shape with the center P as the center, as shown in FIGS.
The fixed neck wall 43 is located in the resonance part 42. The fixed neck wall 43 is fixed to the resonance part 42. The fixed neck wall 43 constitutes a part of the neck portion of the frequency variable resonator 41.
As shown in FIGS. 3 and 4, the fixed neck wall 43 includes a fixed neck wall A 43 a and a fixed neck wall B 43 b.

The shape of the fixed neck wall A43a is a semi-cylindrical shape with the center P as the center. The fixed neck wall A43a is fixed to the radially outer end of the opening 42a (the entire arc-shaped edge of the opening 42a).
The shape of the fixed neck wall B43b is a flat plate shape. The fixed neck wall B43b is formed integrally with the fixed neck wall A43a, or is formed separately from the fixed neck wall A43a and fixedly attached to the fixed neck wall A43a. The fixed neck wall B43b extends from one side in the circumferential direction of the semi-cylindrical fixed neck wall A43a to the center P in the radial direction of the fixed neck wall A43a.

The fixed frequency resonator 44 is located in the resonance unit 42. The fixed frequency resonator 44 can rotate around the center P with respect to the fixed neck wall 43. As shown in FIG. 2, the fixed frequency resonator 44 is coupled to the drive actuator 45 by a rotating shaft 45a. The frequency fixed resonator 44 has a hole 44a connected to the engine intake system, and an extending portion 44b extending from the edge of the hole 44a to the inside of the frequency fixed resonator 44. The hole 44a and the extending portion 44b constitute a neck portion of the frequency fixing resonator 44. The neck cross-sectional area, the neck length, and the resonance chamber volume of the frequency fixed resonator 44 are constant.
The fixed frequency resonator 44 constitutes a part of the neck of the variable frequency resonator 41. The fixed frequency resonator 44 and the fixed neck wall 43 constitute a neck portion of the variable frequency resonator 41.

As shown in FIGS. 3 and 5, the frequency fixed resonator 44 includes a cylindrical portion 44c, first and second semicircular portions 44d and 44e, and a flat plate portion 44f.
The cylindrical portion 44c has a semicylindrical shape with the center P as the center.
The first semicircular portion 44d is disposed at one end in the axial direction of the cylindrical portion 44c (the end on the opening 42a side). The first semicircular portion 44d has the same shape (including substantially the same) as the opening 42a, and has a semicircular shape centered on the center P. Since the first semicircular portion 44d has the same shape as the opening 42a, the size of the opening 42a decreases as the angle at which the frequency fixing resonator 44 rotates around the center P increases. The hole 44a is provided in the first semicircular portion 44d.
The second semicircular portion 44e is disposed at the other axial end of the cylindrical portion 44c. The second semicircular portion 44e has the same shape (or substantially the same shape) as the opening 42a, and has a semicircular shape centered on the center P.
The flat plate portion 44f closes the opening of the space formed by the cylindrical portion 44c, the first semicircular portion 44d, and the second semicircular portion 44e.
The portion excluding the neck portion composed of the hole 44a and the extending portion 44b from the space surrounded by the cylindrical portion 44c, the first semicircular portion 44d, the second semicircular portion 44e, and the flat plate portion 44f is a frequency. This is a resonance chamber of the fixed resonator 44.

  When the frequency fixing resonator 44 moves in the direction of the arrow in FIG. 3 with respect to the fixed neck wall 43, the size of the opening 42a of the resonance portion 42 changes. Therefore, when the fixed frequency resonator 44 moves with respect to the fixed neck wall 43, the neck cross-sectional area of the variable frequency resonator 41 changes.

The drive actuator 45 is a motor. The motor moves the fixed frequency resonator 44. The drive actuator 45 moves the fixed frequency resonator 44 based on the signal from the arithmetic processing unit 30.
The rotation angle detector 46 detects the rotation angle of the frequency fixed resonator 44 and feeds back the signal to the arithmetic processing unit 30.

Here, the operation of the embodiment of the present invention will be described.
As shown in FIG. 1, the rotational speed detection device 20 detects the rotational speed of the engine 50 and sends the signal to the arithmetic processing device 30. The rotation angle detector 46 detects the rotation angle of the fixed frequency resonator 44 and feeds back the signal to the arithmetic processing unit 30. The arithmetic processing unit 30 determines the rotation angle of the frequency fixed resonator 44 based on the signal from the rotation number detection device 20, and the angle and the angle of the frequency fixed resonator 44 detected by the rotation angle detection unit 46 (angle before movement). And how much the drive actuator 45 is moved is determined. The drive actuator 45 (motor) rotates based on a signal from the arithmetic processing device 30. As the motor rotates, the fixed frequency resonator 44 rotates.

When the fixed frequency resonator 44 rotates and the angle of the fixed frequency resonator 44 reaches a target value, the arithmetic processing unit 30 outputs a motor stop signal to the drive actuator 45, and the motor stops based on the signal. Since the motor stops, the rotation of the fixed frequency resonator 44 stops.
When the angle of the fixed frequency resonator 44 is at a target value, the variable frequency resonator 41 resonates to mute a desired noise frequency. Note that, at any frequency other than the frequency to be silenced, anti-resonance occurs and the sound becomes conversely loud.
When the angle of the fixed frequency resonator 44 is at a target value, the hole 44a of the fixed frequency resonator 44 overlaps the opening 42a, and the fixed frequency resonator 44 silences noise generated at a constant frequency.

FIG. 6 shows that a variable frequency resonator 41 is installed in an intake system of a certain automobile, and some noise reduction frequencies are changed at an arbitrary engine speed, and the intake system noise level at that time is low in the entire noise level. It captures the maximum and minimum values (range of change) of the frequency ratio (ratio value). That is, the angle of the fixed frequency resonator 44 is fixed at a certain angle a, and then the engine speed is changed to obtain data, and then the angle of the fixed frequency resonator 44 is changed to low and then the engine speed is changed. By taking the data and changing the angle of the fixed frequency resonator 44 to C, D, E,..., The maximum and minimum values of the ratio of the low frequency to the total noise level in the intake system noise level It captures the value (range of change). The “low frequency” is set to be greater than 0 Hz and less than or equal to 300 Hz this time.
As a result, the ratio can be freely controlled within the range of change by selectively silencing a desired noise frequency according to the engine speed.
Within this range of change, a target is set so that the proportion of the low frequency linearly decreases in proportion to the engine speed (as the engine speed increases) (see FIG. 7), so as to match the target. The silencing frequency (the angle of the fixed frequency resonator 44) with respect to the engine speed was controlled as shown in FIG.
As a result, as shown in FIG. 9, a characteristic is obtained in which the proportion of the low frequency decreases linearly or almost linearly in proportion to the engine speed.

As shown in FIG. 3, since the variable frequency resonance type resonator device 40 has a frequency fixed resonator 44, noise (air column resonance) that is always generated at a constant frequency regardless of the engine speed is silenced by the frequency fixed resonator 44. it can. Further, since the neck portion of the frequency variable resonator 41 is constituted by the frequency fixed resonator 44 and the fixed neck wall 43, noise whose frequency changes in synchronization with the engine speed when the frequency fixed resonator 44 moves relative to the fixed neck wall 43. (Rotation order component) can be muted. Therefore, it is possible to mute two frequencies simultaneously.

The relationship among the muffling frequency, the sound speed, the neck length, the volume, and the neck cross-sectional area is expressed by equation (a).
f = (c / 2π) {S / (L · V)} ^1/2 (a)
However,
f (Hz): muffling frequency c: sound velocity L: neck length V: volume S: neck cross-sectional area.
In the embodiment of the present invention, when the fixed frequency resonator 44 moves relative to the fixed neck wall 43, the amount of the fixed frequency resonator 44 that enters the space that the fixed neck wall 43 surrounds in the resonance portion 42 changes. Therefore, as the neck cross-sectional area of the frequency variable resonator 41 decreases (increases), the volume of the resonance portion 42 of the frequency variable resonator 41 increases (increases) conversely. That is, as the numerator on the right side of the equation (a) becomes smaller (becomes larger), the denominator on the right side of the equation (a) becomes larger (becomes smaller). Therefore, compared with the case where only the neck cross-sectional area or only the volume is variable, the variable range of the silencing frequency is large, and it is possible to quickly respond to the desired silencing frequency.

Since the neck cross-sectional area and volume of the frequency variable resonator 41 can be changed by moving the frequency fixed resonator 44, the silencing frequency can be changed by using the neck cross-sectional area and the volume. Therefore, the variable range of the silencing frequency is large compared to the case where the silencing frequency is changed by any one of the neck cross-sectional area, the neck length, and the volume. Since the variable range of the silencing frequency is large, even if the amount of moving the fixed frequency resonator 44 is small, the variable range of the silencing frequency is large, and it is possible to quickly respond to the desired silencing frequency simply by rotating the motor.
Further, since the neck cross-sectional area and the volume can be changed by rotating the frequency fixing resonator 44, a plurality of neck shapes are unnecessary. Therefore, space saving can be achieved compared with the case of having a plurality of neck shapes.

1 is a block diagram of a variable frequency silencer system according to an embodiment of the present invention. 1 is a perspective view of a variable frequency silencing system according to an embodiment of the present invention. It is an expansion see-through | perspective perspective view which shows the opening of a resonance part, a fixed neck wall, and a frequency fixed resonator of the variable frequency silencer system of this invention Example. It is an expansion see-through | perspective perspective view which shows the opening of a resonance part and the fixed neck wall of the variable frequency silencer system of this invention Example. It is an expansion see-through | perspective view which shows the frequency fixed resonator of the variable frequency silencer system of this invention Example. In the variable frequency silencing system of the embodiment of the present invention, at any engine speed, several silencing frequencies are changed, and the maximum value and the minimum value of the ratio of the low frequency to the entire noise level in the intake noise level at that time It is a graph of ratio value vs. engine speed which caught (change width). FIG. 7 is a graph of a ratio value versus engine speed, in which a target of a ratio value is set such that a ratio of a low frequency linearly decreases in proportion to the engine speed within the change range shown in FIG. 6. FIG. 8 is a graph of the silencing frequency versus the engine speed when the engine speed and the silencing frequency are controlled to match the target of FIG. 7. FIG. FIG. 9 is a graph of ratio value versus engine speed when control is performed as shown in FIG. 8. FIG. It is a graph of the conventional ratio value versus engine speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Variable frequency silencer system 20 Rotation speed detection apparatus 30 Arithmetic processing apparatus 40 Variable frequency resonance type resonator apparatus 41 Frequency variable resonator 42 Resonance part 42a Resonance part opening 43 Fixed neck wall 44 Frequency fixed resonator 44a Frequency fixed resonator hole 44b Frequency fixed Resonator extension 45 Drive actuator 46 Rotation angle detector 50 Engine

Claims (1)

A variable frequency that selectively silences a desired noise frequency according to the rotational speed of the engine intake system noise generated and changed according to the engine rotational speed of the vehicle by an engine rotational speed detection device, an arithmetic processing unit, and a variable frequency resonance type resonator device. A silencing system,
A variable frequency silencing system that utilizes resonance or anti-resonance, which is a characteristic of the variable frequency resonance type resonator device, such that the higher the engine speed, the lower the ratio of the lower frequency to the overall noise level.

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