Electromagnet Locking Device Current Monitoring
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Solution Overview
Problem
Existing access protection devices for hazardous areas lack effective monitoring of the electromagnet's saturation state, leading to unclear signals and potential unsafe conditions when determining the armature's position relative to the electromagnet, which can result in incorrect assessment of the magnetic circuit's state.
Innovation Solution
A locking device with an electromagnet and armature arrangement that includes a measuring resistor in both the supply circuit and the magnetic coil circuit, allowing for current behavior monitoring during power-on and power-off states, and an evaluation device to measure voltage drops across the resistor, enabling detection of current increases and decreases to determine the magnetic circuit's state accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electromagnet is monitored in the non-saturated area, then the current measurement can detect armature position changes, but the measured signal becomes unclear and ambiguous
Solution Approach 1:
The patent changes the operating parameter of the electromagnet from non-saturated to saturated region. By operating in the saturated region, the magnetic circuit's magnetic flux becomes stable and less sensitive to small armature position changes, providing a clear baseline state. The saturation state is detected through current measurement, and when the armature moves (opening the magnetic circuit), the current change becomes unambiguous and easily detectable, resolving the signal ambiguity problem.
2Measurement precision
If a separate sensor is used to monitor the electromagnet or armature position, then the monitoring accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The patent makes the existing current supply circuit serve dual functions: both powering the electromagnet and monitoring its operational state. By measuring the current through the electromagnet coil, the system can determine whether the armature is in the closed or open position without requiring separate sensors. This multi-functional approach simplifies the device structure while maintaining monitoring accuracy.
Solution Approach 2:
The electromagnet's own current consumption serves as the monitoring signal. The control unit evaluates the current state of the electromagnet by measuring the current it draws during operation, allowing the system to self-monitor its functional state without external sensing components.
3Reliability
If the armature is held firmly to the core during operation, then the locking reliability improves, but the current consumption increases due to continuous saturation
Solution Approach 1:
Instead of continuous current supply, the patent uses periodic current pulses to maintain the armature in the closed position. The control unit applies current in periodic intervals, which is sufficient to maintain magnetic attraction and locking reliability while significantly reducing overall current consumption compared to continuous saturation.
Solution Approach 2:
The patent applies current only when necessary to maintain or establish the locked state, rather than continuous excessive current. By using minimal current pulses sufficient to maintain armature closure, the system achieves reliable locking with reduced energy consumption.
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 ensures reliable monitoring of the magnetic circuit's state, preventing unsafe access to hazardous areas by accurately determining whether the magnetic circuit is closed or open, thereby ensuring the armature is securely held to the core or lifted with appropriate effort, and triggering appropriate safety measures.
Implementation Method 1
The locking device includes an electromagnet and an armature for closing the magnetic circuit of the electromagnet
Implementation Method 2
a measuring resistor are present. It also includes an evaluation device for measuring the voltage drop across the measuring resistor
Data Source
AI summary
A locking device (11, 13, 15) according to the invention serves to lock and release, as well as to monitor the state of a part that blocks or releases access to a hazardous area. The locking device comprises an electromagnet (11) and an armature (13) for closing the magnetic circuit of the electromagnet. The locking device further comprises a supply circuit in which a transistor (2) for connecting a voltage source to the magnetic coil (1) and disconnecting the voltage source from the magnetic coil (1), and a measuring resistor (4) are provided. It further comprises an evaluation device (7, 8) for measuring the voltage drop across the measuring resistor (4) and for evaluating this current measurement. Thanks to the fact that the measuring resistor (4) is also arranged in the magnetic coil circuit, a coil current that occurs only within the coil circuit can also be measured.This current can therefore be used to monitor whether the armature (13) lifts off the core (3) during operation, which induces a current increase in the coil circuit. It can also be used to monitor the current drop when the coil (1) is disconnected from the voltage source. By monitoring the current waveform when the coil (1) is connected to the voltage source and by monitoring the coil circuit for an induced current increase and/or a current drop outside a tolerance range when the voltage source is disconnected from the coil (1), reliable detection of the locking device's condition is ensured.