Electronic Dither for Valve Stiction
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Solution Overview
Problem
Electronically controlled valves experience stiction issues due to lack of responsiveness when in a single position for an extended period, leading to inaccurate fluid control, which is not effectively addressed by existing mechanical dither methods.
Innovation Solution
The implementation of an electronic dither system that allows adjustable frequency and amplitude of a periodic waveform to be coupled with control signals for an actuator, optimizing dither to minimize stiction by varying both frequency and amplitude to match the specific characteristics of the valve system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical dither is used to reduce stiction, then the spool responsiveness is improved, but the system complexity increases
Solution Approach 1:
The patent replaces mechanical dither systems with an electronic dither signal injected into the control circuitry of the electronically controlled valve. This substitution eliminates the need for separate mechanical vibration mechanisms while achieving the same stiction-reduction effect through electronic means, thereby reducing system complexity while maintaining improved spool responsiveness.
Solution Approach 2:
The electronic dither signal serves multiple functions: it reduces stiction to improve spool responsiveness, and it can be adjusted in frequency and amplitude to optimize performance for different operating conditions. This multi-functionality allows a single electronic component to address various control issues without requiring separate mechanical dither mechanisms.
2Reliability
If the control signal value is increased to unstuck the spool, then the spool responsiveness is improved, but the fine control capability is lost
Solution Approach 1:
The patent applies periodic dither signals at specific frequencies that cause the spool to oscillate slightly around its target position. This periodic action prevents the spool from becoming stuck by continuously overcoming static friction, while the small amplitude of the dither signal maintains fine control capability. The periodic nature allows the spool to respond smoothly to control signals without requiring large signal increases.
Solution Approach 2:
The patent utilizes parameter changes in the control signal by superimposing a dither component with specific frequency and amplitude characteristics onto the base control signal. This parameter modification allows the spool to overcome stiction through the oscillatory component while the overall control precision is maintained by keeping the dither amplitude small and controlled, thus preserving fine control capability.
3Reliability
If fixed frequency and amplitude dither is applied, then the stiction is reduced, but the adaptability to different valve characteristics is reduced
Solution Approach 1:
The patent implements dynamic dither parameters where both the frequency and amplitude of the dither signal can be adjusted based on the specific characteristics of the valve and operating conditions. This dynamic adjustment capability allows the dither system to be optimized for different valve types, sizes, and operational ranges, providing adaptability while maintaining effective stiction reduction through tailored signal characteristics.
Data Source
AI summary
A method is disclosed that includes allowing both frequency and amplitude of a periodic waveform to be adjusted. The method also includes creating the periodic waveform having the frequency and the amplitude. The periodic waveform is coupled to at least one control signal. The at least one control signal is provided to an output suitable for coupling to an actuator of an electronically controlled device. An apparatus and computer program product are disclosed.