Tamper Resistant Receptacle Shutter Mechanism for 15 and 20 Amp Plugs
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Solution Overview
Problem
Conventional tamper-resistant electrical receptacles do not provide effective protection for both 15 and 20 amp plugs, as their shutter mechanisms are designed for plugs with parallel blades and fail to prevent insertion of foreign objects or single blades with perpendicular blades.
Innovation Solution
A tamper-resistant assembly featuring a first shutter member with a semi-living hinge and a second shutter member with a blocking body, both movable between open and closed positions, biased by springs to prevent foreign objects and single blades from accessing electrical contacts, while allowing 15 and 20 amp plugs to be inserted correctly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If slideable shutter members are used in conventional receptacles, then tamper resistance is provided for 15 amp plugs with parallel blades, but the receptacle cannot provide effective protection for 20 amp plugs with perpendicular blades
Solution Approach 1:
The shutter mechanism is divided into two distinct shutter members: a first shutter member with a first cam surface for 15 amp plugs, and a second shutter member with a second cam surface for 20 amp plugs. Each shutter member is independently controllable and can be opened by the appropriate plug type, providing both versatility and reliable tamper resistance for different plug configurations
Solution Approach 2:
The shutter members are designed to be dynamically controllable through cam surfaces that respond differently to various plug insertion forces and orientations. The first shutter member pivots on a first axis in response to 15 amp plug insertion, while the second shutter member pivots on a second axis in response to 20 amp plug insertion, allowing the system to adapt its protective behavior based on the specific plug type
2Device complexity
If a single shutter mechanism is used for both 15 and 20 amp plugs, then device complexity is reduced, but the shutter cannot properly respond to perpendicular blade insertion of 20 amp plugs
Solution Approach 1:
The receptacle incorporates a universal shutter system where two shutter members work together to serve multiple functions: the first shutter member responds to parallel blade insertion (15 amp plugs), the second shutter member responds to perpendicular blade insertion (20 amp plugs), and both can be simultaneously opened by properly inserted plugs, providing a unified solution for different plug types
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
The assembly effectively prevents access to electrical contacts by foreign objects and single blades, ensuring safe operation for both types of plugs by using a semi-living hinge to reduce stress and prolong the life of the shutter arm, and springs to maintain the shutter members in closed positions unless a valid plug is inserted.
Implementation Method 1
A spring is provided between the shutter members to bias the shutter members toward closed positions thereof
Implementation Method 2
A first arm of the first shutter member has a semi-living hinge and pivotal movement of a second arm of the first shutter member is substantially prevented by a stop on a front cover of the electrical receptacle
Data Source
AI summary
An electrical receptacle includes a front cover having a rib and a protrusion connected thereto, a back housing secured to the front cover and a tamper resistant assembly disposed between the front cover and the back housing. The tamper resistant assembly includes a base member, first and second shutter members, a first spring disposed between and biasing the first and second shutter members toward closed positions thereof, and a second spring disposed between and biasing the first shutter member away from the front cover. The base member is connected to the back housing. The first shutter member is slidably disposed on the base member and has first and second arms extending from a first cam surface. A second shutter member is slidably disposed on the base member and has a blocking body connected to a second cam surface. The first and second shutter members are movable between open and closed positions.