Reed Switch Safety Interlock for Control Unit Maintenance
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Solution Overview
Problem
Existing electronic control units and actuators pose a risk of injury and explosion hazards due to potential spark discharges when maintenance is performed, as voltage-conducting parts can be exposed during opening of the housing, especially in environments subject to explosion hazards.
Innovation Solution
Incorporation of a switch-off device using a reed switch and a removable permanent magnet that interrupts the power supply when the magnet is removed from the housing, ensuring voltage-conducting parts are isolated from power sources, including energy stores like link capacitors, to prevent spark discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the housing is opened for maintenance or repair, then access to the control unit is enabled, but voltage-conducting parts are exposed creating spark discharge risks
Solution Approach 1:
The switch-off device is activated before opening the housing to preemptively disconnect power supply. The permanent magnet is positioned on the housing exterior beforehand, and when the housing is opened, the magnet moves away from the reed switch, automatically triggering the switch-off action before maintenance personnel are exposed to voltage-conducting parts
Solution Approach 2:
The reed switch acts as an intermediary component between the permanent magnet and the power supply circuit. The magnetic field interaction between the magnet and reed switch provides a non-contact switching mechanism that reliably interrupts the power supply to voltage-conducting parts when the housing is opened
2Ease of operation
If the switch-off device remains permanently supplied with current, then the device is ready for operation, but a certain hazard persists during maintenance
Solution Approach 1:
The power supply state of the switch-off device transitions dynamically between connected and disconnected states based on the housing status. When the housing is closed, the permanent magnet holds the reed switch closed, maintaining power supply for normal operation. When the housing is opened, the magnet moves away, the reed switch opens, and power supply is automatically interrupted for maintenance safety
3Ease of operation
If the permanent magnet is arranged outside the housing, then the switch-off device can be activated by removing the magnet, but the magnet must be precisely positioned to operate the reed switch
Solution Approach 1:
The permanent magnet is extracted from the housing interior and positioned on the exterior surface. This allows the magnet to be easily attached and removed by maintenance personnel without disassembling the housing, while the reed switch remains protected inside the housing. The external positioning simplifies operation while the magnetic field penetrates the housing wall to actuate the switch
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 prevents spark discharges and ensures safety during maintenance by ensuring voltage-carrying elements are currentless, reducing the risk of injury and explosion hazards, particularly in environments prone to explosions.
Implementation Method 1
the reed switch (6) is closed when the permanent magnet (7) is arranged at the housing (3)
Implementation Method 2
The switch-off device (4) comprises at least one reed switch (6) and at least one permanent magnet (7) arranged outside the housing (3) and removable from the housing (3)
Implementation Method 3
The at least one reed switch (6) can be opened by removing the permanent magnet (7) from the housing (3)
Data Source
AI summary
An electronic control unit (1) or an electric actuator (2), respectively, have a switch-off device (4) which includes at least one reed switch (6, 18, 26) and at least one permanent magnet arranged outside the housing (3) and removable from the housing (3). If the permanent magnet (7) is removed from its position of usage at the housing (3), for example in order to perform maintenance of the electronic control unit (1) or of the actuator (2), respectively, the at least one reed switch (6, 18, 26) is opened, as result of which the supply link (8, 10) between the activating terminal (5) and the supply terminals (9, 11) of the control unit are interrupted in order to switch voltage-carrying functional elements of the control unit (1) and/or of the electric actuator (2) to be currentless and thus to effectively prevent an unwanted spark discharge.