Motorized Electric Strike with Lost Motion Anti-Tamper
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Solution Overview
Problem
Existing electric strikes face limitations in power consumption and resistance to tampering, necessitating improvements in their design and functionality.
Innovation Solution
The electric strike incorporates a housing with a keeper, a plunger, a cage, and a locking element, along with a motor-driven transmission system that includes a lost motion connection and anti-tamper mechanism to enhance security and control access by selectively preventing radially outward movement of the locking element and retraction of the plunger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor-driven transmission system with lost motion connection is used, then resistance to tampering is improved, but device complexity increases
Solution Approach 1:
The patent introduces a lost motion connection as an intermediary mechanism between the motor and the locking element. This connection includes a ratchet mechanism that allows the motor to drive the locking element in one direction while preventing reverse movement, thereby providing tamper resistance without requiring a complex bidirectional control system. The intermediary mechanism simplifies the overall control architecture while enhancing security.
Solution Approach 2:
The anti-tamper mechanism is designed to be self-actuating through the lost motion connection. When tampering attempts occur, the ratchet mechanism automatically engages to prevent reverse rotation of the motor shaft, eliminating the need for additional sensors or control logic to detect and respond to tampering attempts. This self-service approach reduces complexity while maintaining reliability.
2Reliability
If the sleeve is structured to selectively prevent radially outward movement of the locking element, then security is improved, but ease of operation deteriorates
Solution Approach 1:
The sleeve is designed with dynamic characteristics that allow it to selectively constrain the locking element. During normal operation, the sleeve permits controlled movement through designed clearances and flexible sections. However, when tampering forces are applied, the sleeve's rigidity and geometric constraints automatically engage to prevent radially outward movement of the locking element. This dynamic behavior provides both security and ease of operation without requiring complex control systems.
3Reliability
If anti-tamper mechanism is incorporated, then resistance to tampering is improved, but device complexity increases
Solution Approach 1:
The anti-tamper mechanism is merged with the existing motor-driven transmission system rather than being implemented as a separate, independent mechanism. The lost motion connection serves dual functions: transmitting motor power to the locking element and providing anti-tamper protection. This merging approach eliminates the need for additional separate anti-tamper components, thereby reducing overall device complexity while maintaining enhanced security.
Data Source
AI summary
An exemplary electric strike includes a housing and a keeper pivotally mounted in the housing. The strike also includes a plunger having an extended position and a retracted position, a cage including an aperture, and a locking element movably seated in the aperture. The locking element is engaged with the plunger, and the plunger is structured to urge the locking element radially outward as the plunger moves from an extended position toward a retracted position. The strike also includes a sleeve, a transmission engaged with the sleeve, and a motor drivingly coupled to the transmission. The sleeve is structured to selectively prevent radially outward movement of the locking element and retraction of the plunger. The strike also includes at least one of a lost motion connection and an anti-tamper mechanism.