Seismic Vibrator Servo Valve for Low-Frequency Pressure Error Correction
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Solution Overview
Problem
Existing servo valve technologies for seismic vibrators are inadequate in correcting large pressure perturbations and hydraulic power supply fluctuations, particularly at low frequencies, leading to signal distortion and reduced signal-to-noise ratio.
Innovation Solution
The introduction of additional passageways for linear proportional pressure feedback in the servo valve design, which directly applies sampled pressure to stepped stub pistons, enhancing the valve's ability to counteract pressure errors and fluctuations, thereby improving the actuator's force output and reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional servo valve design is used, then the valve can operate with simple structure, but it cannot effectively correct large pressure perturbations and hydraulic power supply fluctuations
Solution Approach 1:
The patent implements pressure feedback by sampling the actuator pressure through ports and passageways to the spool, creating a closed-loop control system. The sampled pressure acts directly on the spool surface to automatically counteract pressure errors and fluctuations, improving reliability without requiring complex external control systems
Solution Approach 2:
The spool is divided into multiple segments with different drive surfaces (first, second, third, and fourth drive surfaces) that receive pressure feedback from different sources. This segmentation allows independent control of different pressure feedback paths, enabling effective correction of large pressure perturbations while maintaining manageable structural complexity
2Reliability
If hydraulic servo valve is used, then the system can provide force output, but the signal-to-noise ratio is much lower compared to electronic amplifiers
Solution Approach 1:
The pressure feedback mechanism continuously monitors actuator pressure and automatically compensates for deviations, reducing noise in the force output. This closed-loop control improves the signal-to-noise ratio by eliminating pressure fluctuations that would otherwise manifest as noise in the seismic signal
Solution Approach 2:
The patent converts the inherent compressibility of hydraulic fluid, which typically causes pressure fluctuations and noise, into a beneficial feature. By sampling this pressure and feeding it back to the spool, the system uses the fluid's compressibility information to actively cancel pressure errors, transforming a source of noise into a control signal that improves signal quality
3Reliability
If nonlinear pressure feedback is used, then the valve can provide pressure control, but it cannot effectively correct large pressure errors at low frequencies
Solution Approach 1:
The spool is segmented into multiple zones with different drive surface areas that respond to pressure feedback from different actuator chambers. This segmentation creates multiple parallel feedback paths with different gain characteristics, enabling linear proportional pressure feedback that effectively corrects large pressure errors across the full frequency range including low frequencies
Solution Approach 2:
The patent changes the feedback parameter from nonlinear (through orifices) to linear proportional (through direct passageways to stepped surfaces). The stepped spool surfaces provide different effective areas that create a linear relationship between pressure error and corrective force, improving both low-frequency performance and pressure control linearity simultaneously
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
This solution enables the servo valve to better cancel large pressure errors and hydraulic power supply fluctuations, resulting in less distortion and a more ideal force actuator output, improving the signal-to-noise ratio and performance of seismic vibrators, especially at low frequencies.
Implementation Method 1
additional passageways configured to provide linear proportional pressure feedback in spool movement control
Implementation Method 2
additional passageway conducting a portion of sampled pressure from a left cylinder pressure chamber
Data Source
AI summary
An improved servovalve for a seismic vibrator or vibration machine which includes a left additional passageway conducting a portion of sampled pressure from a left cylinder pressure chamber to only a portion of the right end drive surface of the spool, wherein the portion of the right end drive surface is less that of the entirety of the right end drive surface; and a right additional passageway conducting a portion of sampled pressure from a right cylinder pressure chamber to only a portion of the left end drive surface of the spool, wherein the portion of the left end drive surface is less that the entirety of the left end drive surface; thereby providing at least two additional passageways configured to provide linear proportional pressure feedback in spool movement control.