Safety Device for Inspection Doors with Tamper-Resistant Locking
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Solution Overview
Problem
Existing safety systems for inspection doors of machines with moving parts can be tampered with, allowing unauthorized opening, which compromises the safety of operators and exposes them to risk of injury or death.
Innovation Solution
A safety device with an electric lock arranged proximate to the rotation axis, featuring an articulation arm with a tab and slot mechanism that obstructs unauthorized actuator insertion, ensuring the door can only be opened under safe conditions by preventing actuator insertion when the door is not perfectly closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric lock is mounted on the outside of the enclosure with the actuator coupled to the door, then the door can be opened by actuating the electric lock, but the system can be tampered with by inserting a spare actuator to allow motor actuation when the door is open
Solution Approach 1:
The articulation arm is nested within the enclosure, rotating about an axis inside the enclosure rather than having the actuator mounted outside. This nesting approach protects the actuation mechanism from external tampering while maintaining operational functionality.
Solution Approach 2:
The articulation arm acts as an intermediary mechanism between the actuator and the door. It translates the actuator's linear motion into rotational motion of the door, while its rotation path is constrained by the enclosure walls to prevent unauthorized actuator insertion.
2Device complexity
If the electric lock is positioned away from the rotation axis, then the structure is simpler, but the articulation arm cannot effectively prevent unauthorized actuator insertion
Solution Approach 1:
The solution moves the rotation axis from the periphery to the center (rotation axis dimension), allowing the articulation arm to rotate within the enclosed space. This dimensional repositioning enables the arm to leverage the enclosure walls for tamper prevention while maintaining structural simplicity.
3Ease of operation
If the articulation arm rotates freely between closed and open configurations, then the door operation is smooth, but unauthorized opening is possible
Solution Approach 1:
The articulation arm's rotation path is made asymmetric relative to the enclosure space. The arm can rotate freely in the authorized direction (closed to open) but is physically blocked from rotating in the unauthorized direction by the enclosure walls, creating directional asymmetry in movement freedom.
Data Source
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AI summary
A safety device (1) for inspection doors of machines with moving parts, of the type comprising a substantially box-like enclosure (101) inside which there is a chamber (102) for accommodating moving parts and which is provided with at least one inspection port (103) associated with a door (104) that is pivoted about a rotation axis (A) and can move between a closed configuration and an open configuration of the port. The device (1) comprises a safety electric lock (2) provided with a main body (3) associated with a head (4) which bears at least one opening (5) for the insertion of an actuator (6) and is normally closed with the actuator (6) coupled to the main body (3) so as to prevent the opening of the door (104) and is associated with opening actuation means for the release of the actuator (6) so as to allow the opening of the door; the electric lock (2) is adapted to be arranged proximate to the rotation axis (A) with the main body (3) associated with the enclosure (101); an articulation arm (7) being provided which can be associated with the door (104) and is pivoted about a rotation pivot (8) which can be associated with the enclosure (101) at the rotation axis (A), which is associated with a tab (9) provided with a through slot (11); the tab (9) is adapted to obstruct at least partially the opening (5) for the insertion of the electric lock (2) when the actuator (6) is disengaged and the arm (7) rotates between the closed and open configurations of the door (104) and to keep free the opening (5) for the insertion of the actuator (6), passing through the slot (11), and the locking of the rotation of the arm (7) in the closed configuration of the door (104).