JP2013256209A - Device for reducing vehicle interior noise in motor coach - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device configured to effectively reduce vehicle interior noise in a motor coach with two or more seats disposed at given intervals in the longitudinal direction of a vehicle body.SOLUTION: A control sound calculation means 4 is not needed to include signals output from microphones 2A and 2C in calculation, when calculating control sounds emitted from a speaker 3B, since the control sound emitted from the speaker 3B does not enter into the microphone 2A installed at a front adjacent seat 1A and the microphone 2C installed in a rear adjacent seat 1C. As a result, the control sound calculation means 4 expands a control target frequency region while improving calculation speed and computation accuracy, and can largely improve a reduction effect of the vehicle interior noise by the control sound emitted from the speaker 3B.

Description

  The present invention relates to an in-vehicle noise reduction device for a large bus, and more particularly to a technique for reducing in-vehicle noise by radiating control sound from a plurality of speakers provided on a ceiling toward individual seats.

As shown in FIG. 1, the large bus is provided with a plurality of seats 1A, 1B, 1C, etc. with a predetermined interval L in the longitudinal direction of the vehicle body, and an engine, a propeller shaft, The structure is such that the rear wheels are driven by an axle to travel.
As a result, the level of in-vehicle noise generated due to the rotational vibration of the engine differs among the individual seats 1A, 1B, 1C and others according to the distance from the engine.

On the other hand, active noise control is known as a technique for reducing vehicle interior noise (see, for example, Patent Document 1 below).
In this active noise control, as shown in FIG. 3, noise emitted from a noise source is detected by a microphone, and a control sound having the same sound pressure level and frequency as the detected noise is radiated from the speaker. The noise at the position of the microphone is reduced by superimposing the noise and the control sound.

  Thus, in order to reduce the in-vehicle noise in the individual seats of the large bus by active noise control, individual speakers 3A, 3B, 3C, etc. corresponding to the individual seats 1A, 1B, 1C, etc. are arranged on the ceiling. In addition, it is necessary to radiate an optimal control sound from the speakers 3A, 3B, 3C, etc. toward the seats 1A, 1B, 1C, etc.

JP-A-6-51788

  However, for example, when the control sound radiated from the speaker 3B toward the target seat 1B reaches the front and rear seats 1A and 1C, the control sound radiated from the speaker 3A corresponding to the seat 1A and the speaker 3C corresponding to the seat 1C, respectively. And the in-vehicle noise in each seat 1A, 1B, 1C cannot be reduced.

  Further, if control sounds are radiated from the speakers 3A, 3B, 3C, etc. while taking into account the interference between the control sounds, the control system for controlling the operation of the speakers 3A, 3B, 3C, etc. becomes complicated, and the calculation speed is increased. The controllable frequency range is limited or the control effect is reduced due to the limitation.

  Accordingly, an object of the present invention is to provide an apparatus capable of effectively reducing in-vehicle noise in a large bus in which a plurality of seats are arranged with a predetermined interval in the longitudinal direction of the vehicle body.

The present invention for solving the above problems
A device for reducing in-car noise of a large bus in which a plurality of seats are arranged at predetermined intervals in the longitudinal direction of the vehicle body,
A plurality of noise detection means provided for each seat;
A plurality of speakers respectively arranged on the ceiling of the vehicle body corresponding to each seat;
Control sound calculation means for calculating a control sound necessary to cancel noise in each seat detected by the plurality of noise detection means;
Speaker driving means for radiating control sound from each of the plurality of speakers based on the output of the control sound calculating means;
With
The plurality of speakers are controlled toward a predetermined range in which a predetermined position of a front seat next to a target seat to reduce noise is a front limit and a predetermined position of a rear seat next to the target seat is a rear limit. It has a directivity capable of radiating sound.

  In this case, the front limit may be a position that is a predetermined dimension behind the upper end of the seat back of the front adjacent seat.

  Further, the rear limit may be a position that is a predetermined dimension above the upper surface of the seat cushion of the rear adjacent seat along the front surface of the seat back.

  In the interior noise reduction device for a large bus according to the present invention, since the control sound radiated from one speaker and the control sound radiated from the front and rear adjacent speakers do not interfere with each other, the active noise The effect of active noise control can be greatly enhanced while simplifying the control system in control and reducing the cost of the apparatus.

The side view which shows the structure of a large-sized bus. The figure which shows the emission range of the control sound radiated | emitted from a speaker. The figure explaining the principle of active noise control.

  Hereinafter, with reference to FIG. 1 and FIG. 2, an embodiment of a large bus interior noise reduction device of the present invention will be described in detail.

As shown in FIG. 1, the in-vehicle noise reduction device for a large bus according to the present embodiment includes a plurality of microphones (noise detection means) 2A, 2B, 2C and the like, and a plurality of speakers 3A, 3B, 3C and the like disposed on the ceiling of the vehicle body corresponding to the seats 2A, 2B, 2C and the like.
The speakers 3A, 3B, 3C, etc. are arranged on the ceiling of the vehicle body with an interval equal to the seat interval in the front-rear direction of the seats 1A, 1B, 1C, etc.

When an output signal from each of the microphones 2A, 2B, 2C, etc. is input to the control sound calculation means 4, the control sound calculation means 4 can control the frequency of the control sound necessary for canceling the noise in each seat 1A, 1B, 1C, etc. The sound pressure level is calculated and output to the speaker driving means 5.
Then, the speaker driving means 5 drives the speakers 3A, 3B, 3C, etc. based on the control output signal input from the control sound calculation means 4, and radiates control sounds from the speakers 3A, 3B, 3C, etc., respectively.

  At this time, for example, the speaker 3B radiates a control sound in a range indicated by an angle θ in FIG. 2 and exceeds a predetermined position of the seat 1A adjacent to the front of the seat 1B and a predetermined position of the front range and the rear adjacent seat 1C. It has directivity that does not radiate the control sound in the rear range beyond.

Specifically, referring to FIG. 2, the front end position of the speaker 3B is E, the rear end position is F, and the position 20 centimeters backward from the upper end of the reclining seat 1A is the front limit position. A, A position 50 centimeters above the front surface of the seat back from the upper surface of the seat cushion of the seat 1C adjacent to the rear is defined as a rear limit position C.
At this time, the front limit position A is a position determined in consideration of an average seat height and a seat height of an adult sitting on the seat A.
The rear limit position C is a position determined in consideration of the average sitting height of the child seated on the seat C.

At this time, if the angle formed by the front limit position A, the front end position E of the speaker and the vehicle body front direction O is α, and the angle formed by the rear limit position C, the rear end position F of the speaker and the vehicle body rear direction O ′ is β, The angle θ of the range in which the speaker 3B emits the control sound can be expressed by θ = 180− (α + β).
Further, the mounting angle φ of the speaker 2B can be expressed by φ = (α + β) / 2−β.

Thereby, the control sound radiated from the speaker 3B does not enter the microphone 2A provided in the front adjacent seat 1A and the microphone 2C provided in the rear adjacent 1C. When calculating the control sound to be radiated from 3B, it is not necessary to include the signals output from the microphones 2A and 2C in the calculation.
Therefore, the control sound calculation means 4 can greatly increase the effect of reducing the vehicle interior noise due to the control sound radiated from the speaker 3B by increasing the calculation speed and calculation accuracy and expanding the control target frequency range.

Further, the control sound radiated from the speaker 3B does not enter the ears of the passenger seated in the front adjacent seat 1A and the passenger seated in the rear adjacent seat 1C.
Thereby, only the control sound radiated from the speaker 3A is incident on the ear of the passenger seated in the front adjacent seat 1A, and the ear of the passenger seated in the rear adjacent seat 1C is transmitted from the speaker 3C. Only the emitted control sound is incident.
As a result, control sounds radiated from the speakers 3A, 3B, 3C, etc. do not interfere with each other, so that the in-vehicle noise felt by passengers seated in the seats 1A, 1B, 1C, etc. is effective by active noise control. Can be reduced.

1 (1A, 1B, 1C) Seat 2 (2A, 2B, 2C) Microphone 3 (3A, 3B, 3C) Speaker

Claims (3)

A device for reducing in-car noise of a large bus in which a plurality of seats are arranged at predetermined intervals in the longitudinal direction of the vehicle body,
A plurality of noise detection means provided for each seat;
A plurality of speakers respectively arranged on the ceiling of the vehicle body corresponding to each seat;
Control sound calculation means for calculating a control sound necessary to cancel noise in each seat detected by the plurality of noise detection means;
Speaker driving means for radiating control sound from each of the plurality of speakers based on the output of the control sound calculating means;
With
The plurality of speakers are controlled toward a predetermined range in which a predetermined position of a front seat next to a target seat to reduce noise is a front limit and a predetermined position of a rear seat next to the target seat is a rear limit. A large bus interior noise reduction device characterized by having directivity capable of radiating sound.   The in-vehicle noise reduction device for a large bus according to claim 1, wherein the front limit is a position behind a predetermined dimension from an upper end of a seat back of the seat next to the front.   The in-vehicle noise reduction device for a large bus according to claim 1 or 2, wherein the rear limit is a position above a predetermined dimension along the front surface of a seat back from an upper surface of a seat cushion of the rear adjacent seat. .