Thermally sensitive controls
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Solution Overview
Problem
Existing thermally sensitive controls for liquid heating appliances face challenges in reliably latching open multiple pairs of contacts after an overheat protection event, which can lead to incomplete safety features and increased component count, limiting compatibility and manufacturing flexibility.
Innovation Solution
A thermally sensitive control assembly with a dual pole Lift-Off-Reset function, utilizing a single latch arm that extends laterally across the control to prevent both moveable members from returning to the closed position, regardless of which actuator operates first, and a resiliently biased release member to manage the latch arm and moveable members, reducing part count and allowing for both LOR and non-LOR configurations from a single control body design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate latching mechanisms are provided for each moveable member to ensure reliable contact opening, then the reliability of contact latching is improved, but the device complexity and part count increase
Solution Approach 1:
The patent combines two separate latching functions into a single shared latch arm that can simultaneously latch both first and second moveable members. The latch arm extends laterally across the control and includes both first and second latches, allowing one component to perform the latching function for both poles, thereby reducing part count while maintaining reliability
Solution Approach 2:
The latch arm is designed as a universal component that serves multiple functions: it provides latching for both the first and second moveable members, and can operate regardless of which actuator operates first. This multi-functional design eliminates the need for separate latching mechanisms for each pole
2Device complexity
If a single latch arm is shared by both moveable members to reduce part count, then the device complexity is reduced, but ensuring reliable latching of both contacts simultaneously becomes more difficult
Solution Approach 1:
The latch arm is segmented into distinct first and second latches positioned at different locations along its length. Each latch independently engages with its corresponding moveable member, allowing the single latch arm to reliably latch both contacts simultaneously without interference between the latching actions
3Adaptability or versatility
If the control is designed to provide LOR function for both poles, then compatibility with dual pole power supplies is improved, but the manufacturing flexibility and adaptability are reduced due to increased component requirements
Solution Approach 1:
The control is designed with universal LOR capability for both poles through the shared latch arm mechanism. This universal design provides compatibility with dual pole power supplies while maintaining manufacturing flexibility, as the same basic control structure can be used regardless of which pole requires LOR functionality
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 ensures reliable and efficient latching of multiple contacts, reducing the need for additional thermal fuses, enhancing compatibility with dual pole power supplies, and offering manufacturing flexibility by enabling both LOR and non-LOR versions from a single design, thus improving safety and cost-effectiveness.
Implementation Method 1
a first bimetallic actuator 12a and a second bimetallic actuator 12b
Implementation Method 2
a resiliently biased release member (26, 126) is provided which is arranged and constructed such that, when the plunger (30, 130) is released, the release member drives movement of the latch arm (20, 120)
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A thermally sensitive control for controlling a power supply circuit to a heater in a liquid heating appliance. The control comprising: a cordless connector part arranged to mate with a base connector part; first and second moveable electrical contacts mounted on first and second moveable members (16a, 16b); first and second thermally sensitive actuators (12a, 12b), each independently operable to move a respective one of the moveable members (16a, 16b) to interrupt the power supply circuit. The control further comprises a latch arm (20) extending across the control between the moveable members (16a, 16b), the latch arm (20) comprising a first latch for the first moveable member (16a) and a second latch for the second moveable member (16b); and a release member (26) comprising a release part (28) and a plunger (30) projecting from the cordless connector part, wherein the release member (26) is resiliently biased (32) to bring the release part (28) into contact with the latch arm (20) but the resilient bias (32) is overcome when the plunger (30) bears against a surface of the base connector part (8).