Internal Shutter Lock Mechanisms for Safety Receptacles
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Solution Overview
Problem
Current tamper-resistant electrical receptacles face issues with accessibility and ease of use for standard plugs, as well as vulnerability to defeat by foreign objects, particularly due to the need to simultaneously contact ramped shutters and the potential for rejection when receptacles are not at eye level.
Innovation Solution
The development of internal ramped sliding shutters that only open with plug blade insertion, combined with lock control assemblies that ensure safe access by allowing standard plugs to pass through while preventing foreign objects, and the integration of these mechanisms into receptacle designs to address the rejection problem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ramped shutters are used in tamper-resistant receptacles, then safety against foreign objects is improved, but ease of operation deteriorates due to rejection when receptacles are not at eye level
Solution Approach 1:
The shutter is repositioned from an external component requiring simultaneous contact at two points to an internal component that opens via a single-point insertion action. The shutter moves from a position where users must coordinate two-handed pressure to an internal mechanism that responds to the natural single-handed plug insertion motion, effectively changing the dimensional interaction from two-point external contact to one-point internal engagement.
Solution Approach 2:
Instead of having the shutter block the slot from the outside and requiring external force to open it, the invention inverts the approach by having the shutter reside inside the receptacle and be opened by the plug blade pushing it inward. The control mechanism is inverted from external actuation to internal actuation, where the plug blade itself becomes the actuating force that directly pushes the shutter open during normal insertion.
2Reliability
If two lock control mechanisms are used under each receptacle face, then safety is improved, but device complexity increases
Solution Approach 1:
The invention merges the two separate lock control mechanisms into a single integrated control assembly. Instead of having two independent mechanisms that each control individual shutters, the design combines them into one unified control structure that manages both shutters through shared components and coordinated actuation, thereby reducing overall complexity while maintaining the dual-mechanism safety level.
Solution Approach 2:
The lock control assembly is designed with multi-functionality, where a single control mechanism performs the functions of what would traditionally require two separate mechanisms. The unified assembly can independently control multiple shutters and respond to different insertion scenarios, making one component serve multiple safety functions that previously required duplicate mechanisms.
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 solution provides superior safety by ensuring that only standard plugs can access power, eliminating the need for simultaneous shutter contact and reducing the likelihood of rejection, while maintaining ease of use and enhanced security compared to existing tamper-resistant receptacles.
Implementation Method 1
The shutters are spring biased in this closed position and locked in this position by the locking bars
Implementation Method 2
Insertion of plug blades moves the locking bars to an unlocked position, allowing the shutter to move as the plug blades contact ramps, sliding it to the open position
Data Source
AI summary
Four different combinations of a sliding internal shutter and shutter lock control mechanism are described along with methods of incorporating the combinations into receptacles to prevent foreign objects from gaining access to power. Each combination is composed of a ramped shutter, spring biased in a closed position, and two to four lock control mechanisms, each of which moves a locking bar out of contact with an impeding surface on the shutter. The entrance of a standard plug into the assembled receptacle moves all the locking bars away from the shutter's impeding surfaces and the blades interaction with the ramps moves the shutter to the open position allowing the blades to continue to power. The combinations may be installed in receptacles as standalone modules that are installed in a receptacle case or the parts may be integrated directly into a receptacle structure with the proper support structure. These four shutter-lock control mechanism combinations provide superior safety and do not suffer the rejection problem common to the present tamper resistant receptacles. Another three shutters that open by rotary action when the lock control mechanism is in the unlocked state are presented. The safeties of these are similar to the present tamper resistant receptacles but do not have the rejection problem. A method is also provided.