JPH0128571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heating device such as an electric range that boils water and performs heat-retaining cooking.

Conventional configuration and its problems Conventionally, in heating equipment such as electric ranges, a temperature controller such as a thermostat is installed in the center of the heater.
The temperature can be adjusted when keeping warm. However, in this case, manual adjustment had to be made depending on the type of kettle. In addition, the temperature at the bottom varies depending on the type of water boiler, so it is difficult to maintain a constant temperature even if the temperature is maintained at a constant temperature in the center of the heater. It was also difficult to keep warm nearby.

Purpose of the Invention In view of the above-mentioned conventional problems, the present invention indirectly detects the water temperature in the water boiling container by using a temperature sensing element provided in the center of the heater, and regardless of the type of water boiling container or the amount of water. , accurately detects boiling,
The object of the present invention is to provide a heating device that can continue to maintain heat at a temperature close to the boiling point.

Structure of the Invention In order to achieve the above object, the heating device of the present invention is provided with a heating means such as a heater for heating a water boiling container, and includes a temperature sensing element as a part of the component, which is provided in pressure contact with the water boiling container. The temperature of the water in the water boiling container is indirectly detected by a temperature detection device, the gradient detection device detects the gradient of the output of the temperature detection device, and the output of the temperature detection device is stored in a first storage device. The value stored in the first storage device is compared with the output of the slope detection device, and when the ratio becomes less than or equal to a predetermined ratio, an arithmetic device outputs an output; A second storage device temporarily stores the output of the temperature detection device, and compares the stored value of the second storage device with the output of the temperature detection device to determine whether the difference has reached a predetermined difference. The temperature difference determination means makes the determination, and the energization control means controls the energization of the heating means based on a control signal from the temperature difference determination means.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a heating device according to an embodiment of the present invention, in which 1 is an AC power source, and this AC power source 1 is connected to a heating means 3 such as a heater through a power switch 2, and 3 terminals N. A series circuit of energization control means 4 made of a gate thyristor is connected, and a power supply circuit 5 is also connected. 6 is a temperature sensing element consisting of a thermistor (hereinafter referred to as thermistor)
As shown in FIG. 2, this thermistor 6 is brought into pressure contact with the outer bottom surface of the water boiling container 7, and indirectly detects the water temperature within the water boiling container 7. Further, the thermistor 6 is connected in series with a resistor 8 to constitute a temperature detection device 9. The output of this temperature detection device 9 is A/
The signal is input to a D converter 10, and the output of this A/D converter 10 is input to a slope detection device 11. 1
2 is a first storage device, and this first storage device 12
The gradient value calculated by the gradient detection device 11 is temporarily stored. Reference numeral 13 denotes an arithmetic device, which performs a computation process to compare the slope value stored in the first storage device 12 and the slope value outputted from the slope detection device 11 and which changes from time to time, and detects boiling. It is. 14 is a second storage device;
The storage device 14 temporarily stores the output of the temperature detection device 9 when the arithmetic device 13 outputs it. Reference numeral 15 denotes a temperature difference determining means, and this temperature difference determining means 15 compares and processes the stored value stored in the second storage device 14 and the output of the temperature detecting device 9, and controls the energization according to the control signal thereof. The control means 4 controls the supply of electricity to the heating means 3 to maintain the temperature of the water in the water boiling container 7. In addition, 10-15
is a device built into a one-chip microcomputer.

In the above configuration, the operation will be explained below. First, when the power switch 2 is closed, the water boiling container 7 placed thereon is heated by the heating means 3 such as a heater, and the water temperature rises. Since the thermistor 6 is in pressure contact with the outer bottom surface of the water boiling container 7 as shown in FIG. 2, the temperature of the thermistor 6 also rises as the water temperature rises. FIG. 3 shows the rise curve of these water temperatures and thermistor temperatures, where the solid line is the water temperature and the dotted line is the thermistor temperature.

Further, a DC power source is formed by the power supply circuit 5, and first, the A/D converter 10 A/D converts the temperature information of the thermistor 6 and provides it to the slope detection device 11. At this time, temperature information is not captured until the temperature of the thermistor 6 reaches 70°C.

Then, heating progresses and the temperature of thermistor 6 increases.
When the temperature exceeds 70°C, the slope detection device 11 starts calculating the slope. This calculation method counts the time required for the temperature of the thermistor 6 to rise by 2°C. This time is designated as T _N and is temporarily stored in the first storage device 12. Furthermore, the arithmetic unit 13 calculates 2×T _N and stores this value in the first storage device 12 again. Then, compare 2×T _N and the values after T _N+1 ,
When 2×T _N <T _N+M , the arithmetic unit 13 outputs an output, and the temperature T _A of the thermistor 6 at that time is temporarily stored in the second storage device 14 . Then, the temperature difference determination means 15 determines the temperature of the thermistor 6.
Turn on the energization control means 4 so that it stabilizes at T _A -5.
Turn it off to keep warm.

Effects of the Invention As is clear from the above description, according to the present invention, the water temperature in the water boiling container is indirectly detected by a temperature sensing element, and by detecting the temperature gradient that changes from time to time, the initial value is Since the system detects the ratio of the temperature gradient, such as outputting boiling detection when the temperature gradient becomes 1/2 or less, the absolute value of the temperature gradient may differ due to the change in the amount of water, or the boiling temperature may change. Even if the absolute value of temperature changes when the container is changed, the boiling point can be reliably detected, and since the temperature is controlled by setting a predetermined difference based on the absolute temperature of this boiling point, the subsequent heat retention temperature can be adjusted. It has excellent effects such as being able to maintain the temperature near the boiling point and being unaffected by variations in the resistance value of the temperature sensing element made of a thermistor.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a heating device showing an embodiment of the present invention, FIG. 2 is a cross-sectional view of the essential parts, and FIG. 3 is a temperature characteristic diagram. 3...Heating means, 4...Electrification control means, 6...
Temperature sensing element, 7...Kettle, 9...Temperature detection device, 11...Gradient detection device, 12...First storage device, 13...Arithmetic device, 14...Second storage device, 15... ...Temperature difference determination means.

Claims (1)

[Claims] 1. A temperature detection device whose components include a heating means such as a heater that heats a water boiling container, a temperature sensing element that is brought into pressure contact with the water boiling container and indirectly detects the water temperature in the water boiling container, and this temperature detection device. a gradient detection device that detects the gradient of the output of the gradient detection device; a first storage device that temporarily stores the gradient value of the gradient detection device; and a gradient detection device that temporarily stores the gradient value of the gradient detection device; , and an arithmetic device that compares the slope values that change from time to time and outputs an output when the ratio becomes equal to or less than a predetermined ratio, and a device that temporarily stores the output of the temperature detecting device when the arithmetic device outputs an output. a second storage device, a temperature difference determining means for comparing the stored value of the second storage device and the output of the temperature detection device and determining that the difference has reached a predetermined difference; A heating device comprising: energization control means for controlling energization to the heating means based on a control signal from the means.