The present invention relates to controlling temperatures of a cooktop and more particularly to limiting the temperature of a glass-ceramic cooktop such that a maximum temperature of the cooktop reaches about a predetermined maximum temperature.
The new trend in electronically controlled cooktops and/or ranges, typically, includes a cooktop surface composed of a glass-ceramic material that is positioned above one or more radiant heating elements. The electronically controlled cooktop includes various user controls that are operated by a user to adjust the amount of heat and, ultimately, the temperature desired for cooking. The radiant heating elements can be powered by electricity, natural gas or other sources. Typically, the radiant heating element and the user controls are connected to a controller that controls the amount of heat supplied to the cooktop. The electronically controlled cooktop also includes temperature and other sensor that are connected to the controller to aid in controlling the heat supplied by the radiant heating source. The temperature and other sensors can also be used in conjunction with the controller to detect certain conditions that can arise during operation of the cooktop.
To increase the service life of the glass-ceramic cooktop, the temperature of the glass-ceramic cooktop should not exceed a predetermined maximum temperature for extended periods of time. Typically, the temperature of the glass-ceramic cooktop is affected by several factors during operation. The power level selected by the user using a user control interface is an important factor affecting the temperature of the glass-ceramic cooktop. Generally, the user power selection results in a temperature of the glass-ceramic cooktop that is below the predetermined maximum temperature. However, the user power selection along with other dynamics and/or factors involved with the operation of the glass-ceramic cooktop can cause the temperature of the glass-ceramic cooktop to rise above the predetermined maximum temperature. As mentioned above, exposure to a temperature above the predetermined maximum temperature for extended periods of time may reduce the service life of the glass-ceramic cooktop.
The other dynamics and/or factors that affect the glass-ceramic cooktop temperature include, such as, for example, the type of cooking utensil used, the thermal conductivity of the cooking utensil, the contents of the cooking utensil and user manipulation of all of these dynamics and/or factors. The type of cooking utensil affects the temperature of the glass-ceramic cooktop because the size and manufacturer of the cooking utensil can affect the thermal conductivity of the cooking utensil. The thermal conductivity of the cooking utensil relates to the ability of the cooking utensil to transfer heat from the radiant heating element to the contents of the cooking utensil. In addition, factors, such as, for example, the material composition of the cooking utensil, the thickness of the cooking utensil, the flatness and/or warping of the bottom of the cooking utensil also affect the thermal conductivity of the cooking utensil. These factors affect the contact interface area between the cooking utensil and the glass-ceramic cooktop, and the dynamics of this interface area are important factors in determining the thermal conductivity of the cooking utensil. In addition, the contents of the cooking utensil or lack thereof can affect the temperature of the glass-ceramic cooktop because, for example, a cooking utensil that has boiled dry can cause the glass-ceramic cooktop temperature to increase. Additionally, the user can alter or manipulate some or all of these factors/dynamics during the cooking process by, for example, adding more contents to the cooking utensil and/or moving or rocking the cooking utensil on the glass-ceramic cooktop surface during the cooking process.
As stated above, various factors and/or dynamics can cause the temperature of the glass-ceramic cooktop to exceed the predetermined maximum temperature, and therefore, potentially reduce the service life of the glass-ceramic cooktop. Therefore, there is a desire to control the power supplied to the radiant heating element such that a maximum temperature of the glass-ceramic cooktop reaches about the predetermined maximum temperature and/or does not exceed the predetermined maximum temperature within accepted tolerance limits.