Heated lunch box
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Solution Overview
Problem
Existing heated lunch boxes lack the ability to adjust heating temperature and require user observation during the heating process.
Innovation Solution
A heated lunch box with a bimetallic thermostat that includes a mounting support, temperature control shaft, insulation assembly, bimetallic plate, spring plate mechanism, and porcelain post insulator, allowing for preset temperature control and automatic heating adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a preset temperature control mechanism is added to allow temperature adjustment, then the adaptability and ease of operation are improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by using a bimetallic plate that changes its physical state (bending) in response to temperature changes. This allows the thermostat to automatically adjust the circuit connection based on temperature, providing temperature control capability without complex electronic components. The bimetallic plate's physical deformation directly controls the circuit switching, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The bimetallic thermostat is designed to be self-regulating, where the temperature-sensitive bimetallic plate automatically bends and disconnects the circuit when the preset temperature is reached, without requiring external control systems or user intervention. This self-service mechanism provides temperature control functionality while maintaining simple structure, as the system controls itself through physical laws rather than complex control circuits.
2Ease of operation
If a bimetallic thermostat mechanism is implemented for automatic temperature control, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex electronic temperature control systems with a mechanical-bimetallic thermostat mechanism. The bimetallic plate's physical bending in response to temperature changes mechanically opens or closes the circuit, providing automatic temperature control through pure mechanical means. This substitution of mechanical principles for electronic control simplifies the overall system while achieving automatic operation.
Solution Approach 2:
The bimetallic plate serves as an intermediary element that mediates between the heat source and the circuit control. It translates thermal energy into mechanical deformation, which then controls the circuit connection. This intermediary mechanism provides automatic temperature control functionality while keeping the system structurally simple, as the bimetallic plate naturally couples the thermal and electrical systems without requiring complex transducers or sensors.
3Measurement precision
If the bimetallic plate directly contacts the heating element for temperature sensing, then the measurement precision is improved, but the reliability decreases due to safety concerns
Solution Approach 1:
The patent introduces an intermediary structure (the bimetallic plate positioned near but not directly contacting the heating element) that allows temperature sensing without direct contact. The bimetallic plate responds to the thermal field of the heating element, providing accurate temperature sensing while maintaining electrical isolation and safety. This intermediary approach resolves the contradiction by decoupling the sensing function from direct contact with the heat source.
Solution Approach 2:
The temperature sensing function is extracted from direct contact with the heating element. The bimetallic plate is positioned in the thermal field near the heating element to sense temperature changes, but is physically separated to avoid safety issues. This extraction of the sensing function from the heating element itself allows accurate temperature measurement while maintaining safety through spatial separation.
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
Enables preset temperature setting and automatic heating adjustment, enhancing user convenience and reliability.
Implementation Method 1
when the temperature sensed by the thermostat reaches a preset temperature, the bimetallic plate is heated and bends towards the porcelain post insulator
Implementation Method 2
the heating element is press-fitted between the tray and the mounting bracket by the mounting bracket
Data Source
AI summary
Provided is a heated lunch box, including an outer shell, an electric heating device, and an inner container, where the electric heating device is fixedly installed at the bottom of the outer shell, and the inner container is disposed on the electric heating device; the electric heating device and a power supply circuit are connected through a bimetallic thermostat; and the bimetallic thermostat includes a mounting support, a temperature control shaft, an insulation assembly, a bimetallic plate, a spring plate mechanism, and a porcelain post insulator, where the insulation assembly and the temperature control shaft are installed on the mounting support, the spring plate mechanism is installed on the insulation assembly, and two ends of the porcelain post insulator are respectively connected to the spring plate mechanism and the bimetallic plate.