Electric pressure canner with digital control
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Solution Overview
Problem
Traditional pressure canners lack reliable temperature control during the canning process, leading to inefficient heating and potential survival of bacteria and microorganisms due to mechanical pressure relief systems and external heat sensor placement, which can result in temperature fluctuations.
Innovation Solution
A digital pressure canner with a non-contact thermal sensor to measure internal steam temperature in real-time, communicating this data to a digital controller to precisely control the heating element and maintain consistent canning temperatures, reducing overshoot and undershoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a heat sensor is mounted on the canner floor to measure temperature, then the device structure is simple, but the temperature measurement is inaccurate due to heat sink effect and lag
Solution Approach 1:
The patent introduces a radiant barrier (intermediary layer) between the heating element and the canner floor to prevent direct thermal contact. This intermediary blocks heat conduction to the floor, allowing the floor-mounted sensor to measure ambient air temperature rather than the heated floor temperature, thereby resolving the measurement inaccuracy caused by the heat sink effect
Solution Approach 2:
The patent replaces direct thermal conduction measurement (mechanical contact between sensor and heated surface) with radiant/convective measurement (sensor measuring ambient temperature through air). The floor sensor no longer directly measures conductive heat from the heating element but instead measures the ambient temperature field, eliminating the lag and inaccuracy associated with thermal mass effects
2Reliability
If the heat source is set at maximum output level to ensure sterilization temperature, then the sterilization effectiveness is improved, but the temperature fluctuation and energy waste increase
Solution Approach 1:
The patent implements a feedback control system where the floor-mounted temperature sensor continuously monitors ambient temperature and communicates readings to a controller. The controller adjusts the heating element output based on actual temperature readings, reducing power when temperature is sufficient and increasing it only when needed to maintain sterilization conditions, thereby eliminating energy waste from continuous maximum output operation
Solution Approach 2:
The patent transitions from a static maximum-power heating approach to a dynamic heating system that continuously adapts output based on real-time temperature conditions. The heating element operates at variable power levels adjusted by the controller in response to sensor feedback, optimizing energy consumption while maintaining reliable sterilization effectiveness
3Measurement precision
If mechanical pressure relief valves are used to indicate sufficient temperature, then the device complexity is low, but the temperature control precision deteriorates due to noise and user misinterpretation
Solution Approach 1:
The patent replaces mechanical pressure relief valve indicators (rocking motion, whistling noise) with an electronic digital display system. The temperature sensor and controller provide real-time numerical temperature readings on a digital display, giving users precise quantitative feedback about actual canning chamber temperature instead of requiring interpretation of mechanical valve behavior
Solution Approach 2:
The patent introduces a digital display interface as an intermediary between the temperature sensing system and the user. This intermediary translates complex thermal conditions into simple, precise numerical readings, eliminating the ambiguity and misinterpretation issues associated with mechanical pressure relief valve indicators while adding minimal complexity through standard electronic display components
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
Ensures consistent and safe canning temperatures, effectively killing bacteria and microorganisms by maintaining precise temperature control throughout the process, enhancing food preservation and safety.
Implementation Method 1
uses a non-contact thermal sensor to digitally measure internal steam temperature
Implementation Method 2
control the application of heat to the pressure canner appliance
Implementation Method 3
the water begins to boil, which turns to steam
Data Source
AI summary
A digital pressure canner and related methods of operation that provide for improved safety and consistency during a food canning process by reducing temperature over and undershoot. The digital pressure canner includes a digital control operating with inputs from digital sensors to accurately control the canning temperature during the canning process. By reducing over and undershoot of canning temperatures, foods within the pressure canner are maintained at temperatures sufficient to kill any bacteria or microorganisms for the entire canning cycle. In order to verify operation of the digital canner at sufficient canning temperatures, mechanical safety devices, for example, a pressure relief valve can be utilized in conjunction with digital controllers and sensors to provide audible and visual feedback to a user during the canning process.