Marine Vibratory Source Rotary-to-Linear Motion Conversion
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Solution Overview
Problem
Current low frequency vibratory sources used in seismic exploration and monitoring, such as impulsive sound sources, cause environmental harm and are inefficient in producing controlled, repeatable low frequency vibrations, as they are limited by the small displacements of traditional materials like Terfenol-D and piezoelectric/magnetostrictive materials, which struggle to generate the necessary power and bandwidth for seismic applications.
Innovation Solution
A marine sound source with moveable plates driven by a rotary motor and a connection mechanism, such as a crankshaft or camshaft, that translates rotary motion into linear motion, allowing for adjustable displacement and pressure equalization to maintain constant sound pressure levels across varying frequencies, reducing the need for large volume displacements and minimizing unnecessary noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional magnetostrictive materials (Terfenol-D) or piezoelectric materials are used to generate low frequency vibrations, then the device size can be kept small, but the displacement is limited to very small values (about 1/16 inch from a 3-foot stack) which is insufficient for practical seismic applications
Solution Approach 1:
The patent introduces flextensional elements as intermediary components between the magnetostrictive/piezoelectric material and the water. These elements amplify the small displacements of the traditional materials into larger volume displacements of water, enabling practical low frequency seismic sources while maintaining compact device dimensions.
Solution Approach 2:
The patent transforms the operating parameters by using flextensional structures that convert small linear displacements into large volume displacements. This parameter transformation enables the system to achieve the required hundreds of liters of water displacement at low frequencies without requiring proportionally large device dimensions.
2Length of moving object
If flextensional transducers are used to amplify small displacements into larger displacements, then the displacement requirement can be met, but the device becomes heavy, expensive, and highly resonant which limits its effectiveness
Solution Approach 1:
The patent replaces traditional heavy mechanical flextensional transducers with a more efficient system using modern magnetostrictive or piezoelectric materials directly coupled with optimized acoustic radiators. This substitution reduces device weight and cost while maintaining the ability to generate large volume displacements at low frequencies.
3Power
If impulsive sound sources (dynamite or air guns) are used for seismic exploration, then high power can be achieved, but significant broad band noise (up to 1 kHz) is created with much of it outside the useable seismic frequency band, causing environmental harm to marine mammals and other sea life
Solution Approach 1:
The patent applies local quality by designing the acoustic radiator to have frequency-selective properties that concentrate acoustic energy in the useful low frequency seismic band (1-100 Hz) while suppressing higher frequencies. This localized frequency distribution achieves high power in the desired band without creating harmful broad band noise that affects marine life.
Solution Approach 2:
The patent uses dynamically controllable vibratory sources that can precisely control the frequency and waveform of acoustic emissions. This dynamic control enables the system to operate exclusively in the useful seismic frequency range, eliminating harmful high frequency noise while maintaining high acoustic power for effective subsurface imaging.
4Speed
If traditional technologies are used to produce low frequencies (100 Hz and lower), then high and mid frequency applications are well-suited, but the technologies do not scale to produce the low frequencies needed for seismic applications with the necessary bandwidth and power
Solution Approach 1:
The patent transitions from one-dimensional piston motion to three-dimensional volume displacement by using flextensional elements or optimized acoustic radiators. This dimensional change enables the system to displace hundreds of liters of water at low frequencies, achieving the necessary acoustic power and bandwidth for seismic applications that traditional technologies cannot provide.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the production of precise, controlled low frequency vibrations from 1 Hz to 100 Hz, reducing environmental impact and improving seismic imaging results by maintaining consistent sound pressure levels over the desired frequency range, while minimizing the power required to overcome internal pressure changes at deeper depths.
Implementation Method 1
a connection means (either a crank shaft coupled with at least one connecting rod or a camshaft) between the rotary motor and the one or more moveable plates configured to translate rotary motion of the motor into linear motion of the one or more moveable plates
Implementation Method 2
A vibratory source such as a marine vibrator that can impart controlled vibrations over a period of many seconds
Implementation Method 3
The internal fluid can have a higher cavitation threshold than water and be isolated from the external fluid via a bladder
Data Source
AI summary
An acoustic sound source designed to impart vibratory energy into its surrounding environment by linearly displacing transducer face plate(s) that are coupled to a rotary motor via crankshaft/connecting rod(s) or camshaft(s). The frequency of the vibrational energy is proportional to the speed of the rotary motor and the amplitude of the vibrational energy is proportional to the linear displacement of the transducer faceplates. The motor can be manually or automatically controlled to operate at a fixed speed and/or a variety of time varying speeds such as frequency sweeps or ramps. The linear displacement or amplitude of the transducer faceplates can also be manually or automatically controlled to operate at a fixed displacement or to have the displacement vary with time and/or frequency.