Solenoid Plunger Position Detection via Back-EMF Signal Comparison
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Solution Overview
Problem
Existing solenoid drive circuits face challenges in accurately detecting the position of the solenoid plunger, particularly during slow movement and under conditions of solenoid aging or mechanical disturbances, leading to safety and performance issues in applications like aircraft components locking and braking systems.
Innovation Solution
A method and system that utilize a comparator circuit to compare signals with time-delayed envelopes to determine the solenoid plunger position, reducing the current from a pull-in value to a hold value once the plunger reaches its new position, and incorporating fault protection logic to address mechanical and electrical abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional position detection methods are used for solenoid plunger, then the system can detect plunger position, but the detection accuracy deteriorates during slow movement and under solenoid aging conditions
Solution Approach 1:
The patent implements feedback by monitoring the back EMF signal generated by the solenoid coil and using this feedback to detect plunger position. The system continuously compares the actual back EMF signal with an expected signal pattern to determine whether the plunger has reached its target position, enabling accurate detection even during slow movement or under aging conditions.
Solution Approach 2:
The patent replaces traditional mechanical position detection methods with an electrical signal-based detection system. Instead of using mechanical switches or physical position sensors, the system uses back EMF signal analysis to detect plunger position, eliminating the reliability issues associated with mechanical wear and aging.
2Reliability
If high pull-in current is applied to ensure reliable plunger activation, then the solenoid can overcome mechanical disturbances, but energy consumption increases and fault risks arise
Solution Approach 1:
The patent implements dynamic current control by initially applying high pull-in current to ensure reliable plunger activation, then automatically reducing to a lower hold current once position feedback confirms the plunger has reached its target position. This dynamic adjustment maintains activation reliability while significantly reducing energy consumption during the holding phase.
Solution Approach 2:
The system uses position feedback from back EMF signal monitoring to control current levels. When the plunger reaches the target position, the feedback signal triggers automatic current reduction from pull-in level to hold level, optimizing energy usage while maintaining reliability.
3Ease of manufacture
If simple position detection methods are used, then manufacturing costs are reduced, but the system cannot accurately detect plunger position under mechanical disturbances
Solution Approach 1:
The patent replaces complex mechanical position sensors with an electrical back EMF-based detection system. This substitution maintains manufacturing simplicity while improving detection accuracy under mechanical disturbances, as the electrical signal analysis is not affected by mechanical wear or contamination.
Solution Approach 2:
The patent uses the back EMF signal as an intermediary to indirectly detect plunger position. Instead of directly measuring mechanical position, the system measures the electrical signal generated by the coil, which serves as a reliable mediator that reflects plunger position even under mechanical disturbances.
4Reliability
If continuous monitoring of plunger position is implemented, then safety is improved, but system complexity increases
Solution Approach 1:
The patent implements continuous position monitoring through feedback analysis of the back EMF signal. The system continuously compares the actual signal with expected patterns to detect plunger position changes, providing ongoing safety monitoring without requiring additional complex hardware or control mechanisms.
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 approach provides precise solenoid plunger position detection with reduced complexity and manufacturing costs, enhancing safety and performance by automatically switching to a hold current and offering protection against solenoid failures due to aging or mechanical disturbances.
Implementation Method 1
The electrical current flowing through the wire coil creates a magnetic field that either attracts or repels the metallic device
Implementation Method 2
A solenoid is an electromechanical device that transduces or changes an electrical signal, which is input to the wire coil of the solenoid, into a corresponding mechanical movement of a metallic device, such as a rod, disposed within the coil
Data Source
AI summary
Provided are embodiments for determining solenoid plunger position by performing a method which includes generating, by a first signal circuit, a first signal based at least in part on a pull-in current value of a current applied to a solenoid coil of a solenoid. The method further includes generating, by a second signal circuit, a second signal by applying a time delay to the first signal. The method further includes comparing, by a comparator circuit, the first signal and the second signal to determine whether a plunger of the solenoid has moved within the solenoid from a first position to a second position. The method further includes, responsive to determining that the plunger of the solenoid has moved within the solenoid from the first position to the second position, reducing the current applied to the solenoid coil of the solenoid from the pull-in current value to a hold current value.