Blade Spring Contact Device for Compact Motor Circuit Breakers
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Solution Overview
Problem
Existing electrical contact devices for motor circuit breakers are bulky due to the use of coil springs, which limits their performance in compact designs and consumes unnecessary mechanical energy with traditional return springs.
Innovation Solution
A contact device with a leaf spring design, where the movable contact is mounted on an articulated arm with a blade contact pressure spring providing uniform deformation, allowing for compact size and efficient contact closure without the need for a separate return spring, utilizing a ball joint for articulation and a base for lateral positioning to prevent rotation and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a coil spring is used as a contact pressure spring, then the contact device can maintain contact pressure, but the device size becomes large
Solution Approach 1:
The patent changes the physical form of the spring from a coil spring to a blade spring (leaf spring), fundamentally altering the structural parameters while maintaining the elastic function. This parameter change enables the same contact pressure function to be achieved in a much more compact form factor, directly resolving the contradiction between maintaining contact pressure and reducing device size.
2Force
If a coil spring is used for contact pressure, then contact force is maintained, but mechanical energy is consumed unnecessarily
Solution Approach 1:
The patent extracts and eliminates the separate return spring component that was present in traditional coil spring designs. By integrating the contact pressure and return functions into a single blade spring structure, the design removes unnecessary mechanical energy consumption associated with separate spring mechanisms, while still maintaining adequate contact pressure.
3Volume of moving object
If the contact device is reduced to very small dimensions, then compactness is achieved, but manufacturing precision becomes more difficult
Solution Approach 1:
The blade spring is designed with segmented functional zones: a fixed support portion, a deformation portion with specific geometry for uniform stress distribution, and a contact portion. This segmentation allows each zone to be optimized independently, making the manufacturing of small-dimensional components more feasible while maintaining precision. The deformation portion's geometry is specifically designed to distribute stresses evenly, reducing manufacturing tolerances requirements.
4Strength
If the blade spring deforms uniformly over its entire length, then stress distribution is optimized, but the spring design becomes more complex
Solution Approach 1:
The blade spring incorporates local quality variations through its geometry: the width and thickness of the spring vary along its length to achieve uniform stress distribution during deformation. The deformation portion has specific dimensional variations that concentrate flexibility where needed while maintaining structural integrity elsewhere. This localized geometric optimization achieves superior stress distribution without requiring complex multi-component designs.
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 enables high-performance contact devices of very small size, reducing energy consumption and allowing for precise contact alignment and closure, suitable for motor circuit breakers and other applications like switches and contactors.
Implementation Method 1
comprises a blade contact pressure spring mounted in said first support part and comprising an end part resting on the arm and a second end part resting on the first support part so as to return the movable contact(s) to the position of contact with the fixed contact(s)
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The device has a conductor bridge with two movable contacts (6, 7) that are mounted at an end of a contact arm (8), where the contact arm is mounted in a support part. A contact pressure spring in form of blade (10) is placed in the support part between the arm and a cover. The spring has an end part supported on the arm and another end part supported on the support part to return the movable contacts in contact position with fixed contacts (16, 17).