Low frequency sinusoidal vibration mechanism

Abstract

This invention relates to the field of hydrophone measurement and calibration technology, and in particular to a low-frequency sinusoidal vibration mechanism, comprising a fixed frame, a drive mechanism, a guide mechanism, and an open container mounted on the fixed frame. The drive mechanism includes a motor, a reducer, and a swing mechanism. The motor and reducer are respectively mounted on the fixed frame, and the rotating shaft of the motor is connected to the input shaft of the reducer. The rotating shaft of the swing mechanism is connected to the output shaft of the reducer. The guide mechanism is mounted on the fixed frame, and its movable end is connected to the reciprocating swing end of the swing mechanism. The open container is vertically mounted on the fixed frame, and its lower end is fitted with the movable end of the guide mechanism. The open end of the open container faces upward. This invention is used for the precise calibration of the sound pressure sensitivity of hydrophones in the ultra-low frequency range.

Description

Technical Field

[0001] This invention relates to the field of hydrophone measurement and calibration technology, specifically to a low-frequency sinusoidal vibration mechanism. Background Technology

[0002] Various sound waves of different frequencies originating from different natural sources propagate in the ocean. Besides high-frequency, medium-frequency, and low-frequency underwater sounds caused by wind, waves, traffic, and aquatic life, there are also ultra-low-frequency (also known as low-intensity) underwater sounds, with frequencies as low as below 0.1 Hz, caused by ocean currents and earthquakes. To study the characteristics of sound waves in the ocean or to explore and develop the ocean and study climate by utilizing the propagation characteristics of sound waves in the ocean, it is essential to detect sound signals in the ocean. To ensure the accuracy and effectiveness of this detection, acoustic measurement equipment such as hydrophones should be pre-calibrated. Currently, my country has established national benchmarks and the highest defense standards for underwater acoustic pressure in the frequency range of 1 Hz to 5 MHz, but it still lacks benchmarks or standards for underwater acoustic pressure below 1 Hz. Furthermore, the study of water pressure fields in the physical fields utilized by mine fuses and the development of corresponding fuse equipment also require ultra-low-frequency underwater acoustic pressure standards. Therefore, researching and establishing ultra-low frequency underwater acoustic pressure standards below 1Hz is of great practical significance, whether for scientific research, national economic development, or national defense.

[0003] Because the amplitude of the sound source vibration required to generate measurable sound pressure in the ultra-low frequency band is quite large, it is very difficult to generate ultra-low frequency signals in water using conventional methods in the calibration of ultra-low frequency hydrophones. Even with the electrodynamic compensation calibration method, the lowest usable frequency is generally 0.1 Hz, and with the piezoelectric compensation calibration method, it is even higher, generally not lower than 1 Hz. The ultra-low frequency underwater sound waves, characterized by long wavelengths and large vibration amplitudes, acting on the hydrophone in ultra-low frequency calibration are well-suited for simulation using periodically changing hydrostatic pressure. This alternating hydrostatic pressure can be obtained by periodically varying the depth of the hydrophone being calibrated below the free water surface, and is therefore relatively easy to achieve.

[0004] The principle diagram of ultra-low frequency underwater acoustic pressure field generation is as follows: Figure 1 As shown, the measuring water chamber is a stationary container filled with water. The hydrophone being measured is fixedly placed inside the measuring water chamber. The measuring water chamber has a thin neck tube. The water in the chamber is connected to the water in an open container above through this neck tube. The open container makes vertical periodic motion at a very low frequency (displacement d = d0cosωt, displacement amplitude d0). Neglecting the inertial force of the moving water, the hydrostatic pressure (amplitude) generated in the measuring water chamber is p = ρgd0, which yields the alternating hydrostatic pressure required for measurement. As can be seen from the above description, to obtain the alternating hydrostatic pressure, a low-frequency sinusoidal vibration mechanism needs to be designed to drive the open container to make vertical periodic motion. The result of this application is the design of such a low-frequency sinusoidal vibration mechanism. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a low-frequency sinusoidal vibration mechanism for accurate calibration of the sound pressure sensitivity of hydrophones in the ultra-low frequency range.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a low-frequency sinusoidal vibration mechanism, comprising a fixed frame, a driving mechanism, a guiding mechanism, and an open container mounted on the fixed frame. The driving mechanism includes a motor, a reducer, and a swing mechanism. The motor and reducer are respectively mounted on the fixed frame, and the rotating shaft of the motor is connected to the input shaft of the reducer. The rotating shaft of the swing mechanism is connected to the output shaft of the reducer. The guiding mechanism is mounted on the fixed frame, and the movable end of the guiding mechanism is connected to the reciprocating swing end of the swing mechanism. The open container is vertically mounted on the fixed frame, and the lower end of the open container is configured to cooperate with the movable end of the guiding mechanism, with the open end of the open container facing upwards.

[0007] Preferably, the swing mechanism includes a cam disk, a connecting rod, an upper shaft, and a lower shaft. The center of the cam disk is connected to the shaft output end of the reducer. A shaft hole is provided on the cam disk off-center from the disk center. The lower shaft is rotatably installed in the shaft hole. One end of the connecting rod is rotatably connected to the lower shaft, and the other end of the connecting rod is rotatably connected to the upper shaft. The upper shaft is connected to the movable end of the guide mechanism.

[0008] Preferably, the guiding mechanism is a needle roller guide assembly.

[0009] Preferably, a joint joint is provided on the upper shaft, and the end of the joint joint away from the upper shaft is connected to the reciprocating telescopic end of the needle roller guide assembly through a joint nut.

[0010] Preferably, a sleeve is provided on the fixed frame corresponding to the opening container, and a locking screw is provided on the sleeve. The lower end of the opening container is mated with the sleeve, and the locking screw is tightly fitted to the lower end of the opening container.

[0011] Preferably, the sleeve is fitted and fixed to the upper end of the reciprocating telescopic end of the needle roller guide assembly.

[0012] Preferably, the cam disk is provided with a plurality of shaft holes with different distances from the center of the disk.

[0013] Preferably, the motor is a stepper motor.

[0014] Preferably, the reducer is a planetary gear reducer.

[0015] Preferably, the sidewall of the open container is provided with a through hole.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. The new low-frequency sinusoidal vibration mechanism has low redundant vibration and low noise;

[0018] 2. The new low-frequency sinusoidal vibration mechanism has an optimized structure, simplified processing technology, and reduced processing costs;

[0019] 3. The assembly process of the new low-frequency sinusoidal vibration mechanism is simplified, shortening the assembly time;

[0020] 4. The new low-frequency sinusoidal vibration mechanism has a wide vibration frequency range and a wide range of applications. Attached Figure Description

[0021] Figure 1 Schematic diagram of the principle of generating ultra-low frequency underwater acoustic pressure field;

[0022] Figure 2 This is a schematic diagram of the assembly structure of the present invention;

[0023] Figure 3 This is the front view of the present invention;

[0024] Figure 4 This is a side view of the present invention.

[0025] In the diagram: 1. Fixed frame; 2. Needle roller guide assembly; 3. Connector nut; 4. Sleeve; 5. Open container; 6. Locking screw; 7. Reducer; 8. Stepper motor; 9. Cam plate; 10. Joint joint; 11. Upper shaft; 12. Connecting rod; 13. Lower shaft. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 2-4This invention provides a technical solution: a low-frequency sinusoidal vibration mechanism, comprising a fixed frame 1, a driving mechanism, a guiding mechanism, and an open container 5 mounted on the fixed frame 1. The driving mechanism includes a motor 8, a reducer 7, and a swing mechanism. The motor 8 and the reducer 7 are respectively mounted on the fixed frame 1, and the rotating shaft of the motor 8 is connected to the shaft input end of the reducer 7. The rotating shaft of the swing mechanism is connected to the shaft output end of the reducer 7. The guiding mechanism is mounted on the fixed frame 1, and the movable end of the guiding mechanism is connected to the reciprocating swing end of the swing mechanism. The open container 5 is vertically mounted on the fixed frame 1, and the lower end of the open container 5 is configured to cooperate with the movable end of the guiding mechanism. The open end of the open container 5 faces upward. The side wall of the open container 5 is provided with a through hole, and a rubber tube connects the through hole and the sealed measuring water chamber.

[0028] The fixed frame 1 can be fixed to a vibration-damping platform or base. A swing mechanism generates reciprocating oscillation force, and a guide mechanism enables cyclic up-and-down movement, driving the open container 5 to move up and down. When the motor 8 is energized and rotates, it links one end of the open container 5, creating an alternating pressure measurement sound field within the sealed measuring water chamber. By adjusting the rotation speed of the stepper motor 8, the frequency of the alternating pressure sound field can be controlled to meet measurement requirements.

[0029] When the open container 5 vibrates sinusoidally up and down, the water inside it generates an alternating pressure, which is transmitted to the sealed cavity through the rubber tube, providing conditions for the precise calibration of the hydrophone's sound pressure sensitivity.

[0030] The swing mechanism includes a cam disk 9, a connecting rod 12, an upper shaft 11, and a lower shaft 13. The center of the cam disk 9 is connected to the shaft output end of the reducer 7. The cam disk 9 has a shaft hole off-center from the disk center. The lower shaft 13 is rotatably installed in the shaft hole. One end of the connecting rod 12 is rotatably connected to the lower shaft 13, and the other end of the connecting rod 12 is rotatably connected to the upper shaft 11. The upper shaft 11 is connected to the movable end of the guide mechanism. The cam disk 9 has multiple shaft holes with different distances from the disk center.

[0031] The cam crankshaft function is realized through the structural cooperation of cam disk 9, connecting rod 12, upper shaft 11 and lower shaft 13 for driving the reciprocating mechanism. The center of each shaft hole is at a different distance from the center of cam disk 9. The amplitude of the low-frequency sinusoidal vibration mechanism can be adjusted by connecting the connecting rod 12 through different shaft holes.

[0032] The guiding mechanism is a needle roller guide assembly 2, which can convert the rotational motion of the cam disk 9 into the vertical linear motion of the needle roller guide assembly 2. The time-amplitude motion curve of the vertical linear motion is a sinusoidal vibration curve. The needle roller guide assembly 2 has high rigidity, linearity, and high speed. The cross section of its guide shaft for up and down movement is a regular hexagon. It does not rotate and can bear torque, so it can suppress left and right swaying and up and down swaying, and maintain smooth rolling and stable accuracy.

[0033] A joint joint 10 is provided on the upper shaft 11. The end of the joint joint 10 away from the upper shaft 11 is connected to the reciprocating telescopic end of the needle roller guide assembly 2 through the joint nut 3.

[0034] Precision rolling bearings are installed at the two ends of the connecting rod 12, which are fixed to the cam disk 9 and the joint 10 respectively, to reduce the resistance, vibration and noise during the movement of the low-frequency sinusoidal vibration mechanism.

[0035] A sleeve 4 is provided on the fixed frame 1 corresponding to the opening container 5. A locking screw 6 is provided on the sleeve 4. The lower end of the opening container 5 is engaged with the sleeve 4, and the locking screw 6 is tightly engaged with the lower end of the opening container 5.

[0036] The sleeve 4 is fitted and fixed to the upper end of the reciprocating telescopic end of the needle roller guide assembly 2.

[0037] The motor 8 is a stepper motor 8, and the stepper motor 8 adopts the 57 series stepper motor 8.

[0038] The reducer 7 is a planetary gear reducer 7 with a reduction ratio of 10. The planetary gear reducer 7 has the advantages of high rigidity, high precision, and high transmission efficiency, and can effectively reduce redundant vibration and noise of the sinusoidal vibration mechanism.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-frequency sinusoidal vibration mechanism, characterized in that: The device includes a fixed frame, a drive mechanism, a guide mechanism, and an open container mounted on the fixed frame. The drive mechanism includes a motor, a reducer, and a swing mechanism. The motor and reducer are respectively mounted on the fixed frame, with the motor's rotating shaft connected to the reducer's input shaft. The swing mechanism's rotating shaft is connected to the reducer's output shaft. The guide mechanism is mounted on the fixed frame, with its movable end connected to the swing mechanism's reciprocating swing end. The open container is vertically mounted on the fixed frame, with its lower end engaging with the guide mechanism's movable end. The open end of the container faces upwards. The swing mechanism includes a cam disc, a connecting rod, an upper shaft, and a lower shaft. The center of the cam disc is connected to the reducer's output shaft. The cam disc has a shaft hole offset from its center, and the lower shaft is rotatably mounted within this hole. One end of the connecting rod is rotatably connected to the lower shaft, and the other end is rotatably connected to the upper shaft. The upper shaft engages with the guide mechanism's movable end. The guide mechanism is a needle roller guide assembly.

2. The low-frequency sinusoidal vibration mechanism according to claim 1, characterized in that: A joint connector is fitted on the upper shaft, and the end of the joint connector away from the upper shaft is connected to the reciprocating telescopic end of the needle roller guide assembly through a joint nut.

3. The low-frequency sinusoidal vibration mechanism according to claim 2, characterized in that: A sleeve is provided on the fixed frame corresponding to the opening container, and a locking screw is provided on the sleeve. The lower end of the opening container is engaged with the sleeve, and the locking screw is tightly engaged with the lower end of the opening container.

4. The low-frequency sinusoidal vibration mechanism according to claim 3, characterized in that: The sleeve is fitted and fixed to the upper end of the reciprocating telescopic end of the needle roller guide assembly.

5. A low-frequency sinusoidal vibration mechanism according to claim 1, characterized in that: The cam disk is provided with multiple shaft holes with different distances from the center of the disk.

6. The low-frequency sinusoidal vibration mechanism according to claim 1, characterized in that: The motor is a stepper motor.

7. A low-frequency sinusoidal vibration mechanism according to claim 1, characterized in that: The speed reducer is a planetary gear reducer.

8. A low-frequency sinusoidal vibration mechanism according to claim 1, characterized in that: The sidewall of the open container is provided with through holes.

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