Air Break Switch Blade Toggle Mechanism for Stable Contact
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Solution Overview
Problem
High voltage/high current air break switches with low-closing force designs are prone to premature pivoting of blades about their longitudinal axis, leading to unstable electrical connections and inability to close the switch after initial contact.
Innovation Solution
A toggle mechanism with a first toggle member fixedly connected to the blade and a second toggle member pivotally supported by the blade support housing, biased by a compression spring, which inhibits the blade from pivoting about its longitudinal axis until it reaches the closed contact position, ensuring stable engagement with the electrical terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the blade is designed to pivot freely about its longitudinal axis for low-closing force operation, then the closing force is reduced, but the blade may pivot prematurely causing unstable electrical connections
Solution Approach 1:
The toggle mechanism applies preliminary anti-action by using spring biasing to pre-position the blade in a specific orientation about its longitudinal axis. The spring force creates a preliminary counteracting force that prevents premature pivoting, while still allowing the blade to pivot when the toggle mechanism is actuated. This resolves the contradiction by maintaining low closing force through the toggle mechanism while preventing unwanted pivoting through spring biasing.
Solution Approach 2:
The toggle mechanism acts as an intermediary between the operating mechanism and the blade. It translates the operating mechanism's motion into controlled blade pivoting while the spring-biased toggle members mediate the blade's rotational position. This intermediary system allows low closing force operation while preventing premature pivoting that would cause unstable electrical connections.
2Speed
If the blade pivots quickly and stops suddenly during opening, then the opening speed is increased, but momentum causes premature pivoting about the longitudinal axis
Solution Approach 1:
The spring-biased toggle mechanism provides beforehand cushioning by preparing the blade for controlled deceleration before momentum causes unwanted pivoting. The spring force is pre-positioned to engage and gradually reduce the blade's rotational momentum, cushioning the stop and preventing the sudden momentum-driven pivoting that would cause reliability issues while maintaining high opening speeds.
3Force
If the blade bounces off the distal electrical terminal during closing, then the initial contact force is reduced, but the blade rotates about its longitudinal axis before proper seating
Solution Approach 1:
The toggle mechanism performs preliminary action by pre-positioning the blade in the correct rotational orientation about its longitudinal axis before the blade contacts the distal electrical terminal. The spring-biased toggle members ensure the blade is properly oriented in advance, so when contact occurs, the blade is already in the correct position and rotates into stable contact rather than bouncing and rotating improperly.
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 prevents premature pivoting and ensures reliable electrical connection by maintaining the blade in the closed contact position until the toggle mechanism passes over center, allowing for stable operation and preventing unintended return to the open position.
Implementation Method 1
a biasing member forcing the second toggle member to engage the first toggle member
Data Source
AI summary
An electrical switch includes a pivotally supported blade, a toggle mechanism, and an operating mechanism. The operating mechanism is drivable in a first direction to pivot the blade about a first axis and toward a closed blade position. When pivoting toward the closed blade position, the toggle mechanism inhibits the blade from pivoting about a second axis. Upon reaching the closed blade position, continued motion of the operating mechanism in the first direction causes the toggle mechanism to pivot the blade about the second axis toward a closed contact position. In the closed contact position, the blade contacts at least one blade contact to electrically connect the blade and a first electrical terminal.