JP2010024876A - Engine noise silencer of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of an ordinary engine noise silencer of a construction machine that a silencer easily mounted to an existing construction machine at a low price has not been available heretofore. <P>SOLUTION: An engine noise silencer 1 of the construction machine includes a speaker 4 installed in a detachable manner near an engine muffler 3 of the construction machine 2, a microphone 5 for measuring engine noise installed in front of an output of the noise of the engine muffler, and a control device which is electrically connected with the speaker and the microphone installed on the construction machine. The noise of an adverse phase of the noise from the engine muffler is ejected from the speaker 4 to reduce the noise of the construction machine 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a silencer for reducing noise damage caused by an engine of a construction machine at a construction site.

  Conventionally, in construction sites, noises of construction machines, especially construction machinery with moving crawlers, for example, engine noise from excavators and crushers, can be soundproofed around construction sites in order to suppress any noise damage to the surroundings. Panels and soundproof sheets are provided.

  Such an enclosure can reduce high-frequency noise, but it is difficult to reduce low-frequency noise. In order to reduce the noise in the low frequency range, it is necessary to surround with a heavy object (RC wall or the like), and installation and removal are not easy, and the construction period becomes longer and the cost increases.

Therefore, there is a proposal to reduce the engine noise of these construction machines. For example, as described in Patent Document 1, there is known an active silencer (ANC: Active Noise Control) that emits a sound having a phase opposite to that of noise from a speaker in order to mute the inside of a tractor cabin. ing.
Japanese Patent Application Laid-Open No. 08-76772

  However, the conventional silencer is a silencer for the cab of a construction machine, and has a different purpose as an environmental measure for ambient noise. In addition, it has been proposed to provide a silencer directly on the exhaust pipe of the engine to mute the exhaust noise. However, in order to mute the engine noise of construction machinery, it is necessary to provide a silencer on the exhaust pipe. The sound pressure level to be silenced is large, and the cost of the silencer is increased, and it is not easy to easily attach to existing construction machines. Therefore, it is not sufficient as a low noise countermeasure for construction machinery. The engine noise silencer for a construction machine according to the present invention has been proposed in order to solve such problems.

  The gist of the present invention for solving the above-described problems of the engine noise muffler for a construction machine according to the present invention is to provide a speaker detachably in the vicinity of the engine muffler of the construction machine. A microphone for engine sound measurement is installed at the tip of the output, and a control device electrically connected to the speaker and the microphone is provided in the construction machine, and a sound having a phase opposite to that from the engine muffler is transmitted from the speaker. To reduce the noise of the construction machine.

The speaker is provided in the vicinity of the engine muffler;
The speaker is provided with a rotation mechanism for rotating the speaker so that the output direction of the speaker can be changed;
The microphone is supported by an elastic support member having a length in the vicinity of the engine muffler;
Furthermore, the installation housing for attaching the speaker to the housing portion of the construction machine is fixed via a magnet base that is detachably fixed to the metal housing of the construction machine by a magnetic force;
Is included.

  According to the engine noise silencer of a construction machine of the present invention, it is possible to reduce the low sound range in the engine noise of the construction machine. Moreover, the noise can be reduced in all directions by installing the speaker as close as possible to the noise source.

  Further, by rotating the speaker around its vertical axis, it is possible to adjust and set a state where noise can be reduced most. Since the housing for mounting the speaker is detachable with a magnet base, the noise device can be easily transferred to another construction machine and attached, so that noise countermeasures are easy and the cost is reduced.

  As shown in FIGS. 1 to 3, an engine noise silencer 1 for a construction machine according to the present invention detachably attaches a speaker 4 for bass (woofer, subwoofer) in the vicinity of an engine muffler 3 of the construction machine 2. An error microphone 5 is installed as an engine sound measurement microphone before the sound output of the engine muffler 3, and a control device 6 electrically connected to the speaker 4 and the error microphone 5 is installed in the construction machine 2. It is preferable to be provided inside a construction machine such as a driver's cab. Thereby, it can protect from external dust, rain, etc.

  A sound having a phase opposite to that of the noise from the engine muffler 3 is output from the speaker 4 to reduce the noise of the construction machine 2. For example, as shown in FIG. 1, the speaker 4 is provided in the vicinity of the engine muffler 3, for example, on both sides, as speakers 4a and 4b. The speaker 4 is provided as close as possible to the noise source. Thereby, the noise from an engine muffler can be reduced more reliably and effectively.

  Further, as shown in FIGS. 3A and 3B, the speakers 4a and 4b pass through, for example, the centroid of the speakers so that the output directions of the speakers can be changed. A rotation mechanism 7 is provided for rotating the vertical axis a so as to be adjustable. The rotation mechanism 7 is performed by a conventionally known technique, and includes, for example, a drive motor 7a, a rotation transmission belt 7b, a rotation table 7c, and the like. Of course, other known methods may be used.

  In addition, since the said speaker has directivity, the muffling effect may change with the direction. Also, the muffling effect may change depending on the position of the microphone relative to the speaker. Therefore, rotating the speaker and changing the position of the microphone needs to be able to be operated remotely while confirming the mute volume with an ear or a measuring instrument.

  Further, the speaker 4 may be automatically rotated by driving the motor 7a via a control device equipped with a wireless antenna by a remote device by remote control. The rotation range of the rotation mechanism 7 is, for example, a rotation range of about 0 ° to 45 °.

  The microphone 5 is preferably installed in the vicinity of the engine muffler 3 in the exhaust direction, and is supported by an elastic support member 5a having a length. Thereby, exhaust sound can be collected accurately. The support member 5a is formed of a rigid slide overlapping member, and is extended manually or extended electrically. For example, it expands and contracts to about 50 cm to 200 cm. Note that the vertical position adjustment is performed by an appropriate adjustment means.

  A flat plate-like hard mounting housing 9 for attaching the speaker 4 to the housing 2a of the construction machine 2 is provided via a magnet base 8 that is detachably fixed to the metal housing 2a of the construction machine 2 by a magnetic force. Is fixed. A screw rod 8a is erected on the magnet base 8, and the housing 9 is fixed by a nut 8b. A portable silencer that integrates a speaker and a microphone is effective when placed near a noise source, but it must be fixed with a magnet or the like to be attached to a moving body like a construction machine. is there.

The magnet base 8 can be easily magnetically attached by turning ON / OFF the changeover switch. Therefore, it is easy to replace these mufflers 1 with existing construction machines 2. Of course, other known means may be used as the method of attaching the speaker 4 to the construction machine 2 in a detachable manner.

  The said control apparatus 6 is provided in the cab of the construction machine 2, for example. And the result of having experimented with the silencing effect by the silencing device 1 will be described. As shown in FIG. 4, measurement points are determined around the construction machine 2 and measured. An example of the ANC for silence is shown in FIG.

  First, FIG. 6A shows a noise frequency characteristic at an error microphone point when the construction machine 2 is in a hydraulic load state when the engine output is 50% without a silencing action. In the conventional construction machine 2, the 63 Hz band has a peak, which is a major cause of low frequency noise. The sound pressure level in the 63 Hz band is shown in FIG. It can be seen that the engine muffler radiates over a wide area.

  Next, the ANC effect by the silencer 1 of the present invention when the construction machine 2 is subjected to a hydraulic load is shown in FIGS. 6B and 6C as noise frequency characteristics. The sound pressure level in the 63 Hz band at the time of hydraulic operation at the point of the error microphone 5 is 26 dB by ANC, and 15 dB is reduced at the measurement point 8. At any of the measurement points, the sharp peak in the 63 Hz band, which has existed in the past, is not seen, and the effect can be clearly felt in terms of audibility.

  FIG. 7B shows the sound pressure level in the 63 Hz band when the ANC is operated. Obviously, the sound pressure level is lowered at the whole measurement point. FIG. 7C shows the distribution of effect amount of the ANC. The reduction amount in the vicinity of the error microphone 5 shows the maximum, and a reduction effect of 10 dB or more is obtained also in the peripheral portion.

  In the silencer 1 according to the present invention, when a time delay of control was confirmed when the noise fluctuated, as shown in FIG. 8, with respect to the sound pressure level fluctuation in the 63 Hz band accompanying the hydraulic operation, The control effect is exhibited with a delay of about 4 seconds, and a great reduction effect is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view from the rear of a construction machine 2 equipped with a construction machine engine noise silencer 1 according to the present invention. It is a schematic structure front view which shows the attachment condition of the engine noise silencer 1 of the construction machine of the same invention. It is the schematic structure top view (A) which shows the attachment condition of the engine noise silencer 1 of the construction machine of the same invention, and a partial enlarged front view (B). It is explanatory drawing which shows the measurement position for testing the effect of the engine noise silencer 1 of the construction machine of the same invention. It is a block diagram which shows an example of the control system in the engine noise silencer 1 of the construction machine of the same invention. It is a figure (A)-(C) which shows the noise characteristic by engine noise silencer 1 of the construction machine of the present invention. It is a sound pressure level distribution map (A)-(C) which shows the silencing effect of the engine noise silencing apparatus 1 of the construction machine of the same invention. It is a figure which shows the follow-up property of the control with respect to a fluctuating sound of the engine noise silencer 1 of the construction machine of the same invention.

Explanation of symbols

1. Construction equipment engine noise silencer,
2 construction machinery, 2a housing,
3 Engine muffler,
4 (4a, 4b) speaker,
5 Error microphone, 5a Support member,
6 Control device,
7 rotation mechanism, 7a motor,
7b belt, 7c rotary table,
8 Magnet base, 8a Screw rod,
8b nut,
9 Stationary frame.

Claims (5)

A control in which a speaker is detachably provided in the vicinity of the engine muffler of the construction machine, a microphone for engine sound measurement is installed in front of the engine muffler sound output, and the speaker and the microphone are electrically connected. An apparatus is provided in the construction machine,
Noise from the engine muffler is output from the speaker to reduce the noise of the construction machine,
An engine noise silencer for construction machinery. The speaker must be installed near the engine muffler.
The engine noise silencer for a construction machine according to claim 1. The speaker is provided with a rotation mechanism that rotates the output direction of the speaker so that it can be changed.
The engine noise muffler for a construction machine according to any one of claims 1 to 2. The microphone is supported near the engine muffler by an elastic support member having a length,
The engine noise silencer for a construction machine according to any one of claims 1 to 3. The installation case for attaching the speaker to the case part of the construction machine is fixed via a magnet base that is detachably fixed to the metal case of the construction machine by a magnetic force,
The engine noise muffler for a construction machine according to any one of claims 1 to 4.

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