JPS60176895A - Propeller noise control device - Google Patents

Abstract

PURPOSE:To improve the accuracy of under water acoustic observation by reducing the propeller cavitation of an observation vessel resulting in a noise source as low as possible. CONSTITUTION:The underwater noise generated from a propeller 1 is detected by a sensor 2 and is input to a processing section 3. Simultaneously with this, the existent number of propeller rotations is detected by an axial tachometer and input to the processing section 3. The propeller noise is recognized and evaluated by the processing section 3. When the noise generated by the propeller 1 is increased in comparison with a preset allowable value, a propeller pitch angle reduction signal is transmitted to a speed controller 4 from the processing section 3 through a mode selection switch 8. Then, a signal synthesized with an external command 6 is transmitted to a propusion unit and the propeller rotation speed is reduced. As a result, the propeller noise level is reduced and the obstacle in acoustic observation is decreased.

Description

[Detailed description of the invention] The present invention relates to a propeller noise control device.

Vessels that use acoustic equipment to conduct underwater research and observation, such as oceanographic research vessels, are exposed to noise (
Cavitation noise from propellers interferes with acoustic signals during survey and observation work, making underwater communications unclear and reducing the reliability of measurement data.

To address these drawbacks, efforts have been made to design programs that are less likely to cause cavitation at the design stage of the propeller itself, but it is nearly impossible to completely prevent noise generation.

The present invention was proposed in view of these circumstances, and focuses on the fact that maintaining the speed of a ship that conducts research and observation using acoustic equipment is often less important, and aims to minimize the noise level. An object of the present invention is to provide a propeller noise control device.

To this end, the present invention uses a sensor attached to the hull outer plate to detect own ship's propeller noise, and compares the propeller noise output from the sensor with a set noise level, and outputs an output when the propeller noise exceeds the set noise level. A processing unit that outputs
It is characterized by comprising a speed control device which inputs the output of the processing section through a mode changeover switch and reduces the propeller rotation speed or propeller pitch angle in response to a control signal synthesized with an external command.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the circuit configuration thereof.

In the above diagram, ■ is the propeller which is the source of underwater radiation noise, and 2 is the sensor attached to the bottom shell of the stern above the propeller, which detects the noise generated by the propeller. Be able to use a meter.

A processing section 3 processes the noise detected by the sensor 2 into a command signal based on a sound level, and performs, for example, frequency analysis, waveform analysis, filtering processing, etc.

4 is a speed controller, in which a processing section 3 synthesizes a signal and an external command 6 signal to generate a propeller rotation speed or pitch angle control signal.

5 is a propulsion device, which operates in response to control signals from speed controller 4;

Reference numeral 7 denotes a shaft rotation needle that detects the propeller rotation speed and feeds it back to the processing section 3.

Reference numeral 8 denotes a mode changeover switch for selecting whether or not control is required based on the sound level of noise from the propeller 1. The mode changeover switch is turned off during normal high-speed navigation when no observations are made using acoustic equipment.

In such a device, the underwater noise generated by the propeller 1 is detected by the sensor 2, the propeller rotation speed at that time is detected by the shaft rotation needle 7, the propeller noise is identified and evaluated by the processing unit 3, and the propeller noise is set in advance. When the noise generated by the propeller l becomes thicker than the specified tolerance value, a deceleration signal for reducing the rotation speed range or propeller pitch angle is transmitted from the processing unit 3 to the speed controller 4 via the mode changeover switch 8, and an external command is sent. 6 and the combined command signal are transmitted to the propulsion device 5 to reduce the propeller noise level and reduce disturbance to the audio equipment.

According to such a device, cavitation noise, which is the dominant noise generated by the propeller, is generated when the propeller load is large, such as when the ship speeds up or turns during survey/observation operations, so it can be Cavitation noise can be reduced without placing excessive load on the propeller.

This device works effectively because there are very few cases in which high-speed force must be maintained during surveys and observations using acoustic equipment.

In short, according to the present invention, the propeller noise output from the sensor is compared with the set noise level by a sensor attached to the hull outer plate that detects own ship's propeller noise, and when the propeller noise exceeds the set noise level. and a speed control device that inputs the output of the processing section via a mode changeover switch and reduces the propeller rotation speed or propeller pinch angle based on a control signal synthesized with an external command. , propellers that interfere with acoustic observations (
5) Since a noise control device is obtained, the present invention is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. l... Propeller, 2... Sensor, 3... Processing unit, 4... Speed controller, 5... Propulsion device, 6... External command, 7... Shaft rotation needle, 8 ...Mode changeover switch. Sub-Agent Patent Attorney Masafumi Tsukamoto (6)

Claims (1)

[Claims] A sensor attached to the hull shell plate detects the propeller noise of the own ship, and the propeller noise output from the sensor is compared with the set noise level, and when the propeller noise exceeds the set noise level, the output is sent to the output processing unit. , a propeller noise control device comprising: a speed control device which inputs the output of the processing section via a mode changeover switch and reduces the propeller rotation speed or propeller pitch angle by a control signal synthesized with an external command; Device.