Explosion-Proof Key Switch Copper Jacket Flame Barrier
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Solution Overview
Problem
Conventional key switches are unsuitable for vehicles in explosive gas environments due to complex structures, high failure rates, and inconvenient operation, with no commercially available true explosion-proof solutions.
Innovation Solution
An explosion-proof key switch design featuring a switch seat, cover plate, rotating shaft, microswitch, copper jacket, annular disc, spring, steel ball, and positioning pin, with narrow clearances and a protrusion-groove structure to prevent explosive flame propagation and ensure reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional key switches are used in explosion-proof vehicles, then the vehicle can be started, but the switch is extremely prone to failure and cannot be used in explosive gas environments
Solution Approach 1:
The copper jacket acts as an intermediary component between the rotating shaft and the explosive environment. It provides a controlled interface that allows mechanical rotation while preventing explosive flame propagation, with clearances specifically designed to block flame extension
Solution Approach 2:
The copper jacket creates a protected environment around the rotating shaft, effectively isolating the internal components from the explosive external atmosphere. The narrow clearances maintain an inert barrier that prevents explosive gases from reaching ignition sources inside the switch
2Object-affected harmful factors
If lever mechanism is used to switch contacts, then the key switch can be adapted for explosion-proof vehicles, but the structure becomes complex and bulky
Solution Approach 1:
The invention extracts and eliminates the complex lever mechanism from the key switch design. By using a direct rotating shaft connection with a microswitch, it removes unnecessary intermediate components while maintaining explosion-proof functionality through the copper jacket clearance design
Solution Approach 2:
The invention replaces the mechanical lever mechanism with a simpler direct rotational actuation system. The rotating shaft directly actuates the microswitch without intermediate levers, reducing mechanical complexity while the copper jacket provides the required explosion-proof barrier
3Reliability
If several actions are required to start vehicles, then explosion-proof function is achieved, but operation becomes inconvenient
Solution Approach 1:
The invention merges the explosion-proof function with single-action operation by integrating the copper jacket clearance design directly into the key switch housing. This allows the switch to maintain explosion-proof capabilities while responding to a single key rotation action, eliminating the need for multiple separate operations
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 design achieves a simple, cost-effective, and reliable explosion-proof key switch with convenient operation, effectively preventing explosive flame extension and enhancing maintenance, while maintaining a compact structure.
Implementation Method 1
both a clearance between the copper jacket and the rotating shaft and a clearance between the copper jacket and the switch seat have a width less than 0.2mm and a length larger than 12.5mm, so as to effectively prevent explosive flame of explosive gas mixture from extending to the exterior through clearances between components of the switch
Implementation Method 2
a spring and a steel ball are placed in the blind hole
Implementation Method 3
an rolling wheel being in contact with a longitudinal cutting surface of the notch is provided at one side of a drive end of an elastic rod mounted on the microswitch
Data Source
Figure 1
Figure 2
AI summary
An explosion-proof key switch has a switch seat and a cover plate (6). A switch lock core (1) and a rotating shaft (7) connected with each other are provided in the switch seat (2). An output end of the rotating shaft (7) extends through the cover plate (6) to the outside of the switch seat (2). A microswitch (9) fit with the output end of the rotating shaft (7) is mounted on the cover plate (6). An input end of the rotating shaft (7) is mounted in the switch seat (2) by a copper jacket (5) sleeved on the rotating shaft (7). Both a clearance between the copper jacket (5) and the rotating shaft (7) and a clearance between the copper jacket (5) and the switch seat (2) have a width less than 0.2mm and a length larger than 12.5mm. A notch (14) is provided on an end surface of the output end of the rotating shaft (7). An rolling wheel (15) being in contact with a longitudinal cutting surface of the notch (14) is provided at one side of a drive end of an elastic rod (16) mounted on the microswitch (9), and the other side of the drive end of the elastic rod (16) is in contact with a movable contact (17).