Mechanical Interlock Lever Receptacle Shaft Switch
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Solution Overview
Problem
Conventional power switch and receptacle interlock systems are susceptible to failure, leading to potentially dangerous situations due to reliance on electrical interlocks, key-based access control, and user compliance, which can result in safety risks and operational inefficiencies.
Innovation Solution
A mechanical interlock system using parallel shafts and obstructive disks within an enclosure, where a plug's insertion and locking mechanism aligns through-holes to allow access to the shafts, ensuring the power switch cannot be turned on without a properly inserted plug and preventing the plug from being removed until the switch is grounded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If an electrical interlock system is used, then the system can control the operation sequence of switches and receptacles, but the system is susceptible to failure and can be undermined by electrical system failures
Solution Approach 1:
The patent replaces the electrical interlock system with a purely mechanical interlock system. The mechanical linkage physically connects the receptacle lever to the switch mechanisms, ensuring that the receptacle cannot be energized without the plug being inserted and locked into place. This mechanical substitution eliminates reliance on electrical systems for safety interlocking, thereby resolving the contradiction between automation and reliability.
2Ease of operation
If a key interlock system is used, then access and operation can be restricted and controlled, but the system becomes complicated with key logistics, access control, and secure storage requirements
Solution Approach 1:
The patent extracts the access control function from the key interlock system and integrates it directly into the receptacle mechanism itself. The receptacle lever and locking mechanism become the access control device, eliminating the need for separate keys, key logs, and secure storage systems. This extraction resolves the contradiction by maintaining access restriction while removing the complexity of key management.
3Reliability
If operator training is used to ensure proper operation, then personnel can be educated on safe procedures, but the system remains vulnerable to human error and non-compliance
Solution Approach 1:
The patent implements a self-enforcing mechanical interlock system that automatically prevents unsafe operations regardless of operator knowledge or compliance. The physical linkage ensures that the receptacle cannot be energized without proper plug insertion, and the plug cannot be removed while the switch is on. This self-service mechanism resolves the contradiction by making safety independent of operator training and voluntary compliance.
4Reliability
If conventional protection schemes are used, then some safety measures can be implemented, but the systems can be easily overcome through duplicate keys, neglect, or malicious action
Solution Approach 1:
The patent inverts the traditional approach by making the unsafe state physically impossible rather than relying on preventing safe states from being accessed. The mechanical interlock ensures that the only way to energize the receptacle is through proper plug insertion and lever operation, and the only way to remove the plug is to first turn off the switch. This inversion resolves the contradiction by making safety inherent to the operation sequence rather than relying on preventing circumvention.
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 system provides a reliable and safe mechanism to prevent accidental energization or disengagement, ensuring the power switch is only activated with a locked plug and can only be disengaged when both power and grounding switches are properly set, enhancing user and equipment safety.
Implementation Method 1
The push rod receives a linear force from the insertion of the plug into the receptacle and transmits it to an off-center portion of a first disk which converts the linear force into to a torquing or torquative rotary force which angularly displaces the receiving disk
Implementation Method 2
This second push rod itself transmits another linear force to a second disk. An off-center portion of the second disk receives the displacement of the second pushrod and converts this to a torquative or rotary force acting to angularly displace the second disk
Data Source
AI summary
A mechanical interlock of a lever operated receptacle with a shaft operated switch is disclosed and provides mechanically interlocked electrical service to cord-connected equipment such as wheeled gantries, vehicles docked at port terminals, heavy manufacturing, and mining equipment. The power transmission safety system locks a plug into a receptacle until a main power switch has been disengaged and a grounding switch has been engaged. Only if the receptacle is switched off and grounded will the receptacle allow a plug to be inserted. The power transmission safety system is mechanically prohibited from being engaged or ungrounded until a plug has been inserted into the receptacle and locked into place. To again unlock and remove the plug from the receptacle, the power transmission safety system must be deactivated and grounded.