Thermal Protector Arc Prevention via Bent Plate Airflow
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Solution Overview
Problem
Conventional thermal protectors in electrical apparatuses generating hot air with high flow rates and high currents face challenges in preventing arcs from flying to conductive portions, especially in narrow spaces where effective partition walls are impractical, leading to malfunctions and damage.
Innovation Solution
A thermal protector design featuring a bimetallic element, a movable plate, and bent plate planes arranged at a prescribed angle to guide airflow and prevent arcs from reaching conductive parts, with the bent plate planes formed on the movable plate to direct airflow and limit arc expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the thermal protector is provided with exposed switch structures (bimetal, contact) for highly effective thermal response, then the thermal response speed is improved, but arcs can fly to conductive portions causing malfunctions
Solution Approach 1:
The patent divides the thermal protector structure into distinct functional zones: the exposed switch structures (bimetal and contacts) for thermal response are separated from conductive portions by introducing partition walls and insulating structures. This segmentation allows the thermal response function to remain exposed while preventing arcs from reaching conductive parts, thus resolving the contradiction between response speed and arc prevention reliability.
Solution Approach 2:
The patent introduces partition walls and insulating structures as intermediary elements between the exposed switch structures and conductive portions. These intermediaries block the path of arcs while allowing the thermal response structures to remain exposed and functional, thereby maintaining fast thermal response while preventing arc-induced malfunctions.
2Reliability
If partition walls are introduced to prevent arcs from flying to conductive portions, then arc prevention reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the partition wall structure with the existing insulating plate and housing structures. Instead of adding completely separate partition walls, the design integrates arc prevention functionality into existing structural elements, thereby reducing overall device complexity while maintaining arc prevention reliability.
Solution Approach 2:
The insulating plate and housing structures serve multiple functions: they provide mechanical support, electrical insulation, and arc prevention through integrated partition walls. This multi-functionality reduces the need for additional dedicated components, thereby maintaining reliability while minimizing increases in device complexity.
3Productivity
If the cross-sectional area of the air outlet is reduced to increase flow rate, then the airflow rate is improved, but the arc expansion is enhanced by flowing air
Solution Approach 1:
The patent segments the air outlet into multiple smaller outlets or channels. This segmentation increases the total flow rate by creating multiple flow paths while limiting the expansion of arcs in each individual channel, as arcs have more difficulty expanding across multiple separated outlets rather than one large outlet.
Solution Approach 2:
The patent introduces insulating barriers or partition structures within the air flow path that act as intermediaries. These intermediaries constrain arc expansion while allowing air flow to pass through, thereby maintaining high airflow rates while preventing arcs from expanding uncontrollably in the high-velocity air stream.
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
Effectively prevents arcs from causing damage by stabilizing airflow and directing arcs away from conductive parts, enhancing the thermal protector's performance in high-flow, high-current environments.
Implementation Method 1
a bimetal that inverts a bending-back direction treating a set temperature as a boundary
Implementation Method 2
a bent plate plane formed by being bent at a prescribed angle from a plate plane of the movable plate in a side portion of a tip side from a center portion of the movable plate in a vicinity in which the movable contact of the movable plate is arranged
Implementation Method 3
Effectively prevents arcs from causing damage by stabilizing airflow and directing arcs away from conductive parts
Data Source
AI summary
A thermal protector includes, in a fixed manner, a first terminal and a second terminal that are respectively connected to external circuits, at lower left/right ends of the longitudinal directions of a base, and a right end at which a movable plate and a bimetal are superimposed is fixed to the right end of the upper surface of the base and is connected to the second terminal. A fixed contact is fixed to an internal end of the first terminal that is exposed in the left end of the base. A movable contact is fixed at a position facing the fixed contact on the lower surface of the left end of the movable plate. A partition wall that encloses the movable contact and the fixed contact from three directions is provided and bent plate planes are formed on both sides of the movable plate in the vicinity of the movable contact. The bent plate planes adjust the flow direction of hot air in cooperation with the partition wall so as to prevent a malfunction of a breaking arc flying to surrounding conductive members.