Liquid heating vessels
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Solution Overview
Problem
Existing induction kettles on induction hobs suffer from inconsistent and unreliable automatic power shut-off and steam whistle functionality due to varying sensitivities of heating plates and unpredictable orientations, leading to inefficiencies and safety concerns.
Innovation Solution
A kettle design featuring a movable ferromagnetic heating plate with a thermally sensitive actuator, allowing manual intervention and reset, and a steam-activated mechanism that ensures reliable object detection sensing by the induction hob, with a Curie point temperature range between 110°C and 260°C for safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ferromagnetic heating plate is used in an induction kettle, then the kettle can be heated on an induction hob, but the automatic power shut-off becomes unreliable due to varying sensitivity of the hob's object detection sensing
Solution Approach 1:
The heating plate's magnetic properties are changed by controlling its temperature relative to the Curie point. When the plate is heated to near its Curie point temperature, its magnetic permeability changes, causing the induction hob's object detection sensing to become insensitive and automatically shut off power. This provides reliable automatic shut-off across different hob models by exploiting the fundamental magnetic property change rather than relying on mechanical position detection.
Solution Approach 2:
The mechanical lifting mechanism found in prior art is replaced with a thermal-magnetic control system. Instead of mechanically moving the heating plate away from the hob surface, the system uses thermal heating to change the plate's magnetic properties, which in turn causes the hob's electromagnetic sensing to fail and trigger automatic shut-off. This substitution eliminates mechanical complexity and improves reliability.
2Object-affected harmful factors
If the heating plate is lifted away from the base to prevent dry boiling, then safety is improved, but the automatic power limiting becomes inconsistent due to unpredictable plate orientation
Solution Approach 1:
The mechanical lifting system is replaced with a thermal-magnetic system that controls the heating plate's magnetic properties through temperature management. By heating the plate to its Curie point temperature, the system causes the hob's object detection to fail, triggering automatic power shut-off. This eliminates the need for mechanical lifting and the associated orientation problems, providing consistent and reliable automatic power limiting.
Solution Approach 2:
The key parameter changed is the magnetic permeability of the heating plate through temperature control. When the plate reaches its Curie point temperature, its magnetic properties change fundamentally, causing the induction hob's electromagnetic sensing to become insensitive. This parameter change provides a reliable trigger for automatic shut-off that is independent of the plate's mechanical position or orientation.
3Extent of automation
If a thermally activated actuator is used to move the heating plate, then automatic shut-off is achieved, but the device complexity increases with additional components
Solution Approach 1:
The heating plate itself serves as the actuator by utilizing its own thermal response to reach the Curie point temperature. The plate's magnetic properties change automatically as it heats up, triggering the hob's object detection to fail and shut off power. This self-service approach eliminates the need for separate thermal actuators, bi-metallic strips, or complex mechanical mechanisms, reducing device complexity while maintaining automatic shut-off functionality.
Solution Approach 2:
Mechanical actuation systems (bi-metallic strips, shape memory alloys, levers, springs) are replaced with a thermal-magnetic control system. The heating plate's magnetic properties are controlled through temperature management, and when the plate reaches its Curie point temperature, the hob's electromagnetic sensing fails, triggering automatic shut-off. This substitution eliminates mechanical complexity while achieving reliable automation.
4Device complexity
If the heating plate is made stationary, then the structure is simpler, but over-boiling occurs leading to excessive steam generation and power waste
Solution Approach 1:
The heating plate performs dual functions: it serves as both the heating element and the thermal sensor. As the plate heats up during normal operation, it automatically reaches its Curie point temperature, triggering the hob's object detection to fail and shut off power. This self-service thermal response prevents over-boiling and energy waste without requiring additional sensing components or complex structures.
Solution Approach 2:
The magnetic permeability parameter of the heating plate is utilized as a thermal response indicator. As the plate temperature increases during heating, its magnetic properties change at the Curie point, causing the induction hob's electromagnetic sensing to become insensitive and trigger automatic shut-off. This parameter change provides an automatic stop mechanism that prevents energy waste from over-boiling.
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 provides consistent and reliable automatic power limiting and shut-off, enhancing safety and efficiency by allowing manual control of the heating plate's position and reducing induced electric current, thus preventing over-boiling and dry boil scenarios.
Implementation Method 1
a thermally sensitive actuator... a steam chamber fluidly connected to the upper portion of the main body of the vessel, a releasable latching or retaining arrangement for the actuator which incorporates a thermally sensitive device set to operate at a predetermined temperature when influenced by the proximity of steam entering the steam chamber
Implementation Method 2
Liquid heating device for use on an induction hob... A ferromagnetic heating plate is arranged to be located inside the vessel adjacent to the base of the vessel
Implementation Method 3
an optional dry boil arrangement discloses a heater plate composed of two or more parts where one part moves in relation to another to reduce the electrical current flowing in the heater plate/s and is actuated by a shape memory material upon it attaining a predetermined temperature
Implementation Method 4
CN202051519U employs a bi metallic component as the thermal sensor within an assembly that is a known steam switch component commonly used in other kettle arrangements, where the bi metal components movement and force is amplified via a lever, spring and toggle mechanism acting as the actuator to lift the heating plate
Data Source
Figure 1~2
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Figure 4
AI summary
A liquid heating device, for use with an induction hob, comprises a liquid heating vessel and a ferromagnetic heating plate (5) arranged to be located inside the vessel adjacent to the base (3) of the vessel. The ferromagnetic heating plate (5) is arranged to be movable vertically in a substantially perpendicular direction away from the base (3) of the vessel and return. An arrangement to lift the ferromagnetic heating plate comprises a thermally sensitive actuator (11, 12, 14, 15, 16), wherein the ferromagnetic heating plate (5) is mechanically coupled to the thermally sensitive actuator. The thermally sensitive actuator comprises a means to store energy (11), a steam chamber (13) fluidly connected to the vessel, and a releasable latching mechanism (15) for the actuator which incorporates a thermally sensitive device (14) set to operate at a predetermined temperature when influenced by the proximity of steam entering the steam chamber (13) from boiling water in the vessel. The thermally sensitive actuator further comprises means to facilitate a manual intervention of the actuator's operation and permitting a user to set or reset the actuator's position.