Noise reduction device for work vehicle operator

Abstract

To provide a noise reduction device for work vehicle operator which alerts an operator by allowing the operator to hear abnormal sound indicating abnormal conditions of an engine or machine body malfunction while eliminating unpleasant noise which occurs during operation so as to perform pleasant operation with a work vehicle operated by the operator.SOLUTION: The noise reduction device for work vehicle operator is configured to capture environmental sound generated around a machine body using a sound collection microphone 1 and to output control sound whose phase is opposite to that of the environmental sound from an opposite phase output circuit 3 to a muffling speaker 4 to muffle the environmental sound. When analyzing environmental sound captured into the sound collection microphone 1 with a sound source analysis circuit 2 and detecting unique sound different from normal noise registered in sound source data 5, the noise reduction device for work vehicle operator outputs the unique sound to the muffling speaker 4.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a noise reduction device used by an operator who operates a work vehicle used in agricultural work or civil engineering work.

Background Art

[0002] A work vehicle uses a diesel engine as a power source and generates a large amount of noise during running or work. Therefore, in Patent Document 1, in order to reduce the noise and vibration generated by the engine mounted on the vehicle body as a noise reduction device for the work vehicle, an idea is described of generating a control sound having a phase opposite to that of the noise so that the noise cannot be heard by the operator who operates the work vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above-described noise reduction device for a work vehicle picks up the noise generated by the vehicle body with a microphone and cancels the noise by flowing a control sound having a phase opposite to that of the noise to a sound deadening speaker near the driver's seat so that the operator cannot hear the noise. Therefore, even if an abnormality occurs in the engine or the vehicle body contacts an obstacle, it is difficult for the operator to notice, and there is a risk of leading to a serious accident.

[0005] An object of the present invention is to provide a noise reduction device for an operator of a work vehicle that can cancel unpleasant noise generated during work so that the operator can perform light work, and can make the operator hear abnormal sounds of an abnormal state of the engine or a malfunction of the vehicle body to prompt attention.

Means for Solving the Problems

[0006] The above problems of the present invention are solved by the following technical means.

[0007] The invention according to claim 1 is a noise reduction device for an operator of a work vehicle that captures ambient noise generated around the vehicle body with a sound collection microphone 1, outputs a control sound having a phase opposite to that of the ambient noise from an inverse phase output circuit 3 to a noise cancellation speaker 4 to cancel the ambient noise, and when a specific sound different from the normal noise registered in the sound source data 5 is detected by analyzing the ambient noise captured by the sound collection microphone 1 with a sound source analysis circuit 2, outputs the specific sound to the noise cancellation speaker 4.

[0008] The invention according to claim 2 is a noise reduction device for an operator of a work vehicle according to claim 1, characterized in that when outputting voice in the ambient noise to the noise cancellation speaker 4, a specific sound is output louder than the voice.

[0009] The invention according to claim 3 is a noise reduction device for an operator of a work vehicle according to claim 1, characterized in that an alarm is issued while a specific sound is being output from the noise cancellation speaker 4.

[0010] The invention according to claim 4 is a noise reduction device for an operator of a work vehicle according to claim 3, characterized in that when the specific sound is thunder, the thunder is output by the noise cancellation speaker 4 and a rainfall warning is issued.

Effect of the Invention

[0011] In the invention according to claim 1, when an operator operates the vehicle body and performs work while driving, the noise generated around the vehicle body is picked up as ambient noise by the sound collection microphone 1, and the control sound having a phase opposite to that of the ambient noise is output from the inverse phase output circuit 3 to the noise cancellation speaker 4, so that the noise generated around the operator is canceled by the control sound. However, when a specific sound different from the normal noise registered in the sound source data 5 is detected by the sound source analysis circuit 2, the specific sound is sent to the noise cancellation speaker 4, and the specific sound is output from the noise cancellation speaker 4, enabling the operator to notice that an abnormal state has occurred in the vehicle body when hearing the specific sound and avoid danger.

[0012] In the invention of claim 2, the human voice included in the ambient sound is directly output to the noise cancellation speaker 4 and can be heard by the operator. However, when a specific sound is detected and output from the noise cancellation speaker 4, it is output louder than the voice, so that even if the operator is in the middle of a conversation, the operator can notice that an abnormality has occurred in the machine body and avoid danger.

[0013] In the invention of claim 3, by outputting a specific sound from the noise cancellation speaker 4 and further issuing an alarm, the operator can surely confirm the abnormality.

[0014] In the invention of claim 4, when thunder is included in the ambient sound, the thunder is output from the noise cancellation speaker 4 and a rainfall warning is issued, so that the operator can be urged to take rainfall countermeasures.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the examples shown in the drawings.

[0017] In FIG. 1, an operator M attaches earphones having a sound collection microphone 1 and a noise cancellation speaker 4 to both ears, collects the noise reaching both ears of the operator M with the sound collection microphone 1, and emits a sound of the opposite phase of the collected sound from the noise cancellation speaker 4 to reduce the loudness of the sound heard by the operator M. The sound of a person speaking, the abnormal sound of an engine, the sound of the machine contacting an obstacle, and the specific sound of thunder are output from this earphone as the noise cancellation speaker 4. When the work vehicle is a tractor and the operator sits in the driver's seat in the cabin and operates it, it is preferable to use a speaker provided in the cabin as the noise cancellation speaker 4.

[0018] During the operation of the work vehicle, conversation with people around is made possible by outputting voice from the noise cancellation speaker 4. However, since a specific sound is output louder than the voice when it occurs, the operator can notice the occurrence of an abnormality.

[0019] FIG. 2 shows the waveform of the noise generated around the work vehicle. The noise includes waveforms with abnormally high waveforms and waveforms with different frequencies as shown in the spectrum diagram of FIG. 3. When the sound collected by the sound collection microphone 1 is graphed as shown in FIG. 2, it is represented by a graph of a wave with the horizontal axis being time and the vertical axis being amplitude. By dividing the sound collected by the sound collection microphone 1 at predetermined time intervals and performing a Fourier transform, data representing the loudness of the sound for each frequency can be obtained. As time passes, data representing the loudness of the sound for each frequency accumulates. Therefore, steady noise data can be obtained by calculating the average value of the accumulated data.

[0020] Even after obtaining the steady noise data, the graph of the wave divided at predetermined time intervals is Fourier-transformed to obtain data representing the loudness of the sound for each frequency in real time. By comparing the data representing the loudness of the sound for each frequency obtained in real time with the steady noise data, if a sound with a frequency not present in the steady noise data or a sound whose loudness exceeds a predetermined value compared to the steady noise data is detected, it is determined that an abnormal sound has occurred.

[0021] Figure 4 is a control block diagram. The sound collection microphone 1 picks up the environmental sound around the aircraft and inputs it to the sound source analysis circuit 2. The sound source is analyzed by Fourier transform. If the analyzed sound source is a specific sound such as an engine abnormal sound, an aircraft contact sound, or thunder, which is different from the normal noise stored in the sound source data 5, it is determined that an abnormal sound has occurred. When the steady-state noise data is subtracted from the data representing the magnitude of the sound for each frequency obtained at this time, only the characteristic data of the abnormal sound remains. Therefore, by performing inverse Fourier transform on this and outputting it, the operator M can effectively hear the sound with only the abnormal sound extracted.

[0022] In addition, if the sound source analysis circuit 2 analyzes that the noise contains voice during the noise, the voice is output as voice by the noise cancellation speaker 4, enabling conversation. However, if the specific sound is included, the voice is made quieter and the specific sound is made louder to alert the abnormal state, and at the same time, it emits "There is an abnormal sound." or "There is thunder." in automatic voice, or displays abnormal characters or blinking on the alarm display device provided on the aircraft. At this time, by storing the characteristic data of the human voice and the characteristic data of the thunder sound in advance, it is possible to detect something similar to the characteristic data in the data representing the magnitude of the sound for each frequency obtained in real time.

Explanation of symbols

[0023] 1 Sound collection microphone 2 Sound source analysis circuit 3 Inverse phase output circuit 4 Noise cancellation speaker 5 Sound source data

Claims

1. In a noise reduction device for an operator of a work vehicle that captures ambient noise generated around the vehicle body with a sound collection microphone (1), outputs a control sound having a phase opposite to that of the ambient noise from an inverse phase output circuit (3) to a noise cancellation speaker (4) to cancel the ambient noise, when a specific sound different from the normal noise registered as sound source data (5) by analyzing the ambient noise captured by the sound collection microphone (1) with a sound source analysis circuit (2) is detected, the specific sound is output to the noise cancellation speaker (4). A noise reduction device for an operator of a work vehicle.

2. The noise reduction device for an operator of a work vehicle according to claim 1, wherein when outputting the voice in the ambient noise to the noise cancellation speaker (4), the specific sound is output louder than the voice.

3. The noise reduction device for an operator of a work vehicle according to claim 1, wherein an alarm is issued while the specific sound is being output from the noise cancellation speaker (4).

4. The noise reduction device for an operator of a work vehicle according to claim 3, wherein when the specific sound is thunder, the thunder is output by the noise cancellation speaker (4) and a rainfall warning is issued.

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