Solenoid Driver Circuit Tuning Resonant Pick Current for Preloaded Latches
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Solution Overview
Problem
Existing solenoid actuated electric latches and strikes face challenges in efficiently overcoming preload conditions, which can cause sluggish or incomplete retraction of the latch or keeper, leading to operational inefficiencies and increased costs by requiring larger solenoids.
Innovation Solution
A solenoid assembly with a switching circuit and function generator that selectively adjusts the frequency of the pick current to resonate with the latch system, inducing vibrations to release the latch or keeper from preload conditions, using MOSFET or GaNFET transistors and a preload sensor to manage current levels and frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger solenoid is used to overcome preload conditions, then the solenoid can reliably retract the latch or keeper, but the cost increases and energy efficiency decreases
Solution Approach 1:
The patent applies mechanical vibration by inducing resonant frequency oscillations in the latch system to overcome preload conditions. The controller detects preload and activates the solenoid at its resonant frequency, causing vibrations that facilitate latch retraction without requiring excessive force from an oversized solenoid, thereby maintaining reliability while reducing energy consumption.
Solution Approach 2:
The patent changes the operational parameters of the solenoid by dynamically adjusting the drive frequency based on detected preload conditions. When preload is detected, the controller modifies the frequency parameter to match the resonant frequency of the latch system, enabling efficient actuation without requiring a larger solenoid design, thus improving energy efficiency while maintaining reliability.
2Reliability
If a larger solenoid is used to overcome preload conditions, then the solenoid can reliably retract the latch or keeper, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical solution of using a larger solenoid with a control-based approach. Instead of increasing solenoid size to overcome preload, the system uses a controller with frequency detection and resonant frequency actuation to achieve reliable retraction. This substitution reduces device complexity and cost while maintaining reliability.
Solution Approach 2:
The patent implements feedback by detecting preload conditions and using this information to adjust the solenoid drive frequency. The controller continuously monitors the system state and modifies its output accordingly, enabling reliable latch retraction under preload without requiring an oversized solenoid, thus avoiding the complexity and cost of a larger mechanical system.
3Use of energy by moving object
If constant current is provided to the solenoid, then power efficiency is improved, but the ability to overcome preload conditions is reduced
Solution Approach 1:
The patent uses mechanical vibration at resonant frequency to amplify the effect of the constant current on the latch system. By inducing vibrations, the system achieves effective latch retraction with lower force requirements, maintaining power efficiency while overcoming preload conditions that would otherwise require higher pull-in force.
Solution Approach 2:
The patent applies periodic action by operating the solenoid at its resonant frequency, creating rhythmic oscillations in the latch system. This periodic excitation accumulates energy in the system and amplifies the effect of the constant current, enabling the solenoid to overcome preload conditions while maintaining power-efficient operation.
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
Effectively alleviates preload conditions by resonant frequency vibration, ensuring efficient retraction of the latch or keeper, improving operational efficiency and reducing the need for oversized solenoids, while providing a method to detect and address potential system issues.
Implementation Method 1
the solenoid is powered away from the default state to bias a return spring
Implementation Method 2
the frequency is adjusted by the function generator until the pick current induces a resulting vibration of the latch system, and wherein upon inducing the resulting vibration of the latch system the latch or keeper is released from a preloaded condition
Data Source
AI summary
A latch system includes a releasably secured latch or keeper and a solenoid assembly. The solenoid assembly has a solenoid driver coupled to a power supply, a switching circuit connected with the solenoid driver, and a function generator to selectively adjust a frequency of a pick current output from the power supply and provided to the solenoid driver. The frequency is adjusted until the pick current induces a resulting vibration of said latch system sufficient to free a preloaded latch or keeper. The adjusted frequency may be a target frequency or a range of frequencies. Also included may be a preload sensor. When a preload is sensed, the frequency may be adjusted by the function generator until the pick current induces a resulting vibration of said latch system sufficient to free a preloaded latch or keeper.