Circuit Breaker Operating Mechanism 4-Bar Linkage
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Solution Overview
Problem
Existing molded case circuit breaker mechanisms face limitations in contact link rotation, high reset force requirements, and complexity due to the use of upper and lower links, connection pins, and latch links, which hinder efficient operation and ergonomic performance.
Innovation Solution
An improved operating mechanism featuring a 4-bar linkage system with a floating pin, extension spring, and rolling friction between the fork link and reset pin, allowing for high contact link rotation, reduced reset force, and simplified components, enabling smoother ON-OFF, TRIP, and RESET operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If upper link, lower link, connection pin and latch link are used in the circuit breaker mechanism, then the mechanism can achieve basic opening and closing functions, but the contact link rotation is limited and the reset force required is high
Solution Approach 1:
The mechanism is divided into functional segments: the 4-bar linkage system (comprising fixed link, input link, coupler link, and output link) separates the opening/closing function from the resetting function. This segmentation allows each component to be optimized independently, enabling high contact link rotation while reducing the reset force required by the spring member.
Solution Approach 2:
The mechanism transitions from static friction (in traditional pinned connections) to rolling friction through the rolling contact between the fork link and reset pin. This dynamic change in friction type significantly reduces the force required to reset the mechanism, allowing the spring member to efficiently return the contact link to its initial position.
2Ease of operation
If traditional pinned connection and cam action between pin and latch link are used, then the mechanism can achieve TRIP and RESET operations, but the reset force is high due to static friction
Solution Approach 1:
The traditional pinned connection relying on static friction is replaced with a rolling contact mechanism between the fork link and reset pin. This substitution transforms the friction type from static to rolling, dramatically reducing the reset force required and improving the ease of RESET operation.
3Reliability
If extra pin is used as stopper for latch link, then the mechanism can achieve proper motion control, but the component count increases
Solution Approach 1:
The fork link serves multiple functions: it acts as a connector in the 4-bar linkage system, provides the rolling contact surface for reduced friction during RESET, and incorporates an integrated stopper feature to control the motion of the latch link. This multi-functionality eliminates the need for separate extra pins, reducing component count while maintaining reliability.
Solution Approach 2:
The stopper function is merged into the fork link structure itself, combining what would traditionally be separate components (fork link and stopper pin) into a single integrated element. This merging reduces the overall component count while maintaining the necessary motion control for reliable operation.
4Ease of operation
If floating pin and rolling friction mechanism are used, then the reset force is reduced and operation is smoother, but the mechanism design becomes more complex
Solution Approach 1:
The mechanism employs a floating pin that can move freely within its link, allowing the connection point to adapt dynamically during operation. Combined with the rolling friction mechanism between the fork link and reset pin, this creates smooth operation. The design complexity is managed by integrating these features into the existing 4-bar linkage structure rather than adding separate complex subsystems.
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 mechanism enables higher contact link rotation, decreases reset force, reduces component count, and enhances ergonomic design, improving the overall performance and efficiency of the circuit breaker.
Implementation Method 1
an extension spring connected between the spring pin and the floating pin
Implementation Method 2
rolling friction between the fork link and reset pin
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to an improved operating mechanism of molded case circuit breaker. The mechanism comprises a fixed contact means (5), a moving contact means (4), a rotor means (2), and a mechanism module (3). The mechanism module (3) comprises side plate means (3a), trip plate means (3k), a lower link means (3b), an upper link means (3c), a latch link means (3d), a fork link means (3e), a spring pin means (3f), a floating pin means (3h), navigation pin means (3l), reset roller pin means (3m) and plurality of spring means (3i).