Traditionally, oven range manufacturers have relied on manual interfaces to control the duration of self-cleaning cycles. A new, low-cost optical sensor called IntelliRange™ has been developed that can automatically control oven self-cleaning, cycle time based on oven loading. The sensor has also shown that it can detect over-cooking of food that may result when consumers enter the wrong cooking temperature or cooking time, mistakes that are normally noticed only when it is too late. In addition, the sensor is able to detect unsafe conditions and automatically send a shutdown signal to the oven control panel.
The sensor developer, Telaire of Santa Barbara, Calif., has been making low cost infrared gas sensors, for the HVAC industry for the past 10 years. Telaire has been making sensors to control the self-cleaning cycle in ovens for the past 18 months. The first generation technology utilized a small low cost infrared spectrometer to measure the gases given off during the beginning of the self-cleaning cycle. The profile of the gas concentrations at the beginning of the cycle is used to determine oven loading. For electric ovens the sensor measures carbon dioxide (CO2 ) and gas ovens measured carbon monoxide (CO).
Cleaning control
The IntelliRange™ sensor is Telaire’s third-generation oven sensor, which has provided a further cost reduction in the technology with increased functionality. Using technology originating from Telaire’s parent company Edwards Systems Technology (a leader in commercial fire detection systems), the current sensor is a very sensitive optical smoke detector that utilizes an on-board microprocessor for measurement, interpretation and analysis. Much like the first generation gas sensors developed by Telaire, the IntelliRange sensor measures the quantity and rate of change in smoke generation during the initial start-up of the self-cleaning cycle. The sensor can distinguish between different oven-soil loadings (as defined by Consumer Union) and select appropriate cleaning-cycle duration that delivers a clean oven with just the right amount of energy usage. The smoke measured by the sensor is generally not visible to the human eye. Fig. 1 shows results of a number of self-cleaning tests where cleaning loads of 10 percent, 30 percent and 100 percent where tested. The sensor shows excellent consistency over a multitude of cycles and, due to its unique design features, does not need calibration or cleaning over its rated life of 15 years.
Automatic control of the self-cleaning cycle offers a lot of advantages to consumers. It eliminates consumer confusion over how long to manually adjust a cleaning period. In addition, because self-cleaning operating time is automatically controlled to only that necessary to clean the oven, energy use and overheating of the kitchen area can be reduced.
Safety shutdown
The IntelliRange sensor can also detect unsafe cooking conditions that could potentially lead to uncontrolled combustion. Fig. 2 also shows the smoke profile for cookies baking in an oven that is too hot. If the level of smoke measured by the sensor rises to the alert level and the warning is unheeded by the consumer, the sensor can then send a shutdown signal to the oven-control panel, eliminating a continuing unsafe condition. This can provide consumers an added degree of comfort knowing that their cooking will be monitored even when they are away from the kitchen.
The IntelliRange sensor is designed to take a sample from the oven via a small tube and is small enough that it can be readily accommodated wherever space is available in the range. The sensor can incorporate the self-cleaning and safety-alarm logic in its on-board microprocessor, allowing for easy integration into existing oven designs.
