Thermal Protector Movable Plate Slim Hole Resistor
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Solution Overview
Problem
Conventional thermal protectors require an additional manufacturing step and increased costs due to the incorporation of a separate resistor component for producing Joule heat, which complicates the design and increases pricing.
Innovation Solution
A thermal protector design that utilizes a bimetal with a warpage direction inverted at a predetermined temperature, where a slim hole partitions the movable plate into a wide-width and narrow-width part, allowing the narrow-width part to function as both a conductor and resistor, eliminating the need for a separate resistor component and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate resistor component is incorporated to produce Joule heat for overcurrent protection, then the thermal responsiveness and current responsiveness are improved, but the device complexity and manufacturing cost increase due to additional components and assembly steps
Solution Approach 1:
The patent merges the resistor function with the movable plate by creating a narrow-width part on the movable plate that serves as an integrated resistor. This eliminates the need for a separate resistor component and its associated assembly steps, thereby reducing device complexity while maintaining the thermal responsiveness function. The narrow-width part is formed by cutting a slim hole through the movable plate, creating a high-resistance path that generates Joule heat for overcurrent protection.
Solution Approach 2:
The movable plate is designed to perform multiple functions: it serves as both the movable contact carrier and the resistor element. The narrow-width part of the movable plate specifically functions as a resistor to generate Joule heat, while the rest of the plate maintains its spring property and contact function. This multi-functionality reduces the total number of components needed in the thermal protector.
2Reliability
If a separate resistor component is incorporated to produce Joule heat, then the current responsiveness is improved, but the manufacturing cost increases due to additional component assembly steps
Solution Approach 1:
The resistor function is merged into the movable plate structure itself. The narrow-width part is created by cutting a slim hole through the movable plate, which forms a high-resistance path. This integration eliminates the need to purchase, inventory, and assemble separate resistor components, thereby reducing manufacturing cost while maintaining current responsiveness.
Solution Approach 2:
The movable plate serves itself by incorporating the resistor function directly into its structure. The narrow-width part of the movable plate generates the necessary Joule heat for overcurrent protection without requiring external resistor components. This self-service approach simplifies the manufacturing process and reduces costs.
3Device complexity
If the movable plate is made with a narrow-width part to function as a resistor, then the need for separate resistor component is eliminated, but the spring property may deteriorate
Solution Approach 1:
The movable plate is segmented into different functional regions: a narrow-width part that serves as the resistor element and a wider part that maintains the spring property. The slim hole cutting creates this segmentation, allowing the narrow portion to provide high resistance while the broader portions of the plate maintain sufficient structural integrity and elastic properties for reliable contact operation.
Solution Approach 2:
Different parts of the movable plate have different local qualities: the narrow-width part has high electrical resistance for Joule heat generation, while the broader parts maintain mechanical strength and spring properties. This local differentiation allows each region to optimize its function without compromising the overall performance of the component.
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
This configuration enhances current and thermal responsiveness with a simple design, reducing processing costs and maintaining high resistance values while preventing deterioration of the spring property, resulting in a reliable thermal protector.
Implementation Method 1
a slim hole, formed by being cut from the fixed part toward the movable contact at a position closer to one of sides from a central line along the central line that links the movable contact and the fixed part, for partitioning the movable part into a wide-width part and a narrow-width part
Implementation Method 2
a bimetal having a fixed part having holes into which the columns are inserted on the insulator, a second terminal, formed at the fixed part, for an external connection, a movable contact formed at a position facing the fixed contact at an end on a side opposite to the fixed part, and an inversion operation part
Data Source
AI summary
A thermal protector has superiority in current responsiveness or thermal responsiveness with a simple configuration that does not need a separate manufacturing step of incorporating a resistor. At a stage of press processing for cutting from an original material, a movable plate body part of a movable plate is partitioned into a narrow-width part and a wide-width part by a slim hole. The movable plate is assembled to a fixed conductor with columns of an insulator, a bimetal is assembled to the movable plate, the entire configuration is pressed down by a resinous block, and the entire fixing part is fixed by melting tips of the columns. The wide-width part serves as a normal movable plate, whereas the narrow-width part serves as a conductor in a normal state and as a resistor against an overcurrent.