JPS624963B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides electric kettles, water boilers, etc.
This invention relates to a boil response device that reliably senses that water inside a container has boiled.

In general, it is desirable for water boiling appliances such as electric kettles to be turned off after the water has boiled, considering their intended use. That is, 100℃ (1
In the case of atmospheric pressure), it is desirable to maintain the temperature for several seconds before turning off the switch, both for drinking water and for the design of the switch. However, the temperature of the water
It is not easy to turn off the switch after keeping it at 100℃ for a few seconds. Previously, it was designated as Special Public Service 50-19101.
Publication No. 19104, Special Publication No. 19104, Special Publication No. 1910-1910-
As seen in Publication No. 19105 and Japanese Patent Publication No. 51-35907, control was performed using a thermostat etc. using conductive heat from a heating element, but in this method, the set temperature range of the thermostat etc. The reality is that it is extremely narrow and strictly controlled, and as it is greatly affected by atmospheric pressure, voltage, water volume, water temperature, and room temperature, it is difficult to operate the switch reliably after boiling, and it is difficult to switch it off before boiling. The movement was inconsistent, such as cutting off. Moreover, the complexity of manufacturing and assembly has led to increased costs.

Also, Special Publication No. 19102, Special Publication No. 1910-1910-
As seen in Publication No. 19103, a method that uses only steam or bubbles during boiling requires a special dry-firing prevention device to ensure safety during dry-firing, resulting in a complicated configuration. , which led to an increase in costs.

Also, a method was proposed to control the temperature by restricting the escape of steam generated by a heating element, but it was difficult to put it into practical use because of large variations such as voltage fluctuations causing the switch to turn off before boiling.

The present invention makes it extremely easy to control the temperature by rapidly raising the temperature of the heat-sensitive member by utilizing the dry firing state caused by air bubbles during boiling. This device uses heat to protect the heating element and eliminate the risk of fire.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

In the figure, 1 is the main body of a kettle, 2 is a lid knob, 3 is a lid, and 4 is a heat-sensitive cover as a partition member made of a metal material with good thermal conductivity. is forming. A cylindrical pipe 5 connects the compartment on the main body 1 side and the heat-sensitive cover 4 side, and opens close to the bottom of the compartment with a certain gap therebetween. Reference numeral 6 denotes a ferrite for temperature control, which is a heat-sensitive member having a Curie point at a constant temperature, and is fixed to the heat-sensitive cover 4.

Reference numeral 7 denotes a heating element such as a sheathed heater installed at the bottom of the main body 1, and is formed into a spiral or curved shape to obtain an appropriate heating surface. It is attached. Further, the heating element 7 has a fixed contact 8 fixed to a terminal portion at its tip.

A magnet 9 is held by a magnet holder 10 so as to face the ferrite 6. The magnetic holder 10 and the heat-sensitive cover 4
A coil spring 11 is interposed between them to bias the magnet 9 and the ferrite 6 in a direction that separates them from each other.

12 is a cover member provided to cover each mechanism of the switch part equipped on the main body 1; 13 is a lever whose one end is supported on a shaft 14; the other end is equipped with a magnetic holder 10; An operation button 15 is fixed to the end. On the other hand, an elastic blade 18 having a contact 18a corresponding to the above-mentioned fixed contact 8 fixed at the end is attached to the back side of the power outlet made of a corner 16 and an insulating ceramic 17, and a blade 18 having elasticity is attached to the end of the power outlet. When the magnet 9 is not attracted to the ferrite 6 by the fixed insulator 19, the blade 18 fixed to the contact 18a is pushed down to open the circuit between the contacts 8 and 18a. Here, at least a portion of the heating element 7 is in contact with a portion of the heat-sensitive cover 4 constituting the compartment.

In the above configuration, the operation will be explained below. Water to be boiled is poured into the main body 1, the appliance plug is connected to the power outlet, and the operation button 15 is pressed.
When the upper part of the magnet 9 is pushed in the direction of arrow a, the magnet 9 moves toward the ferrite 6, and this magnet 9
and ferrite 6 are attracted against the biasing force of the coil spring 11, and the contacts 8, 18a are closed as shown in FIG.
The time period closes, and heating by the heating element 7 begins.

When heating starts, the temperature of the ferrite 6 rises through the heat-sensitive cover 4 in contact with the heating element 7, but at this time, the temperature rise of the ferrite 6 is moderated by the water A in the heat-sensitive cover 4. After a while after electricity is applied, the water temperature of the water A in the heat-sensitive cover 4 rises faster than that of the water B in the main body 1 because the amount of water A is smaller than that of the water B in the main body 1. Then, the warm water A inside the heat-sensitive cover 4 replaces the water B inside the main body 1 by convection, and the ferrite 6 is cooled through the heat-sensitive cover 4, and the ferrite 6 is repeatedly cooled and heated.

Thereafter, when the water temperature in the main body 1 reaches 97° C. to 98° C., bubbles are generated rapidly, and a large amount of bubbles are also generated in the heat-sensitive cover 4 which is in contact with the heating element 7. Then, the water A inside the heat-sensitive cover 4 is pushed out toward the main body 1 side by these bubbles, and the temperature of the heat-sensitive cover 4, which had been receiving heat from the heating element 7 until now, is rapidly increased as the boiling water inside is pushed out. Heat is transferred to the ferrite 6 fixed to the heat-sensitive cover 4, and the ferrite 6 reaches its Kyrie point. At this point, the magnet 9 is automatically removed from the ferrite 6 due to the biasing force of the coil spring 11, and the insulator 19 provided on the lever 13 pushes down the blade 18, breaking contact between the fixed contact 8 and the contact 18a, and the heating element 7, the heat generation stops and the water boiling ends.

According to experiments, "d", "H",
Each dimension of "l" is determined by the wattage of the heating element 7, and the smaller "d", the longer "H", and the smaller "l", the more ferrite 6 will be produced by slight foaming during boiling. The temperature rises rapidly,
The power supply is determined by the dimensions of “d”, “H”, and “l”.
You can select the point (time) to turn off.

FIG. 3 shows the temperature rise curves of each part in the above embodiment, where A is the temperature rise curve of the heating element 7, B is the ferrite 6, and C is the temperature rise curve of the water temperature in the heat-sensitive cover 4.

Curve B depicts a sawtooth-like temperature rise curve, and the amplitude of the ``〓〓〓〓 portion of this temperature rise curve decreases as it approaches boiling, and becomes almost constant just before boiling; This is because the difference between the water temperature in the heat-sensitive cover 4 and the water temperature in the main body 1 decreases as the water approaches boiling.

In addition, since ferrite 6 rises rapidly immediately after boiling, between P and Q of curve B, ferrite 6
It is possible to increase the variation in the operating temperature of ferrite during manufacturing.

In addition, the temperature point "P" of ferrite 6 just before boiling
increases in proportion to the wattage of the heating element 7, that is, the voltage applied to the heating element 7, but at the same time, the stable temperature point "Q" also increases in proportion to the voltage fluctuation. It does not change even if voltage occurs, and can absorb voltage fluctuations.

In addition, in most conventional heat sensing structures, the temperature rise range of ferrite after boiling was about 5 degrees to 15 degrees, but in this example, it was possible to obtain a temperature rise range of 100 degrees or more immediately after boiling. ,
It can absorb the variations in heat-sensing pieces such as ferrite, making it possible to put it into practical use.

As described above, according to the present invention, the bubbles generated during boiling can push out the boiling water in the compartment and bring it into a state close to dry firing.
It is extremely unaffected by water temperature, water volume, room temperature, voltage, etc., and the power can be turned off reliably after boiling. Also, during dry firing, the temperature of the heat-sensitive member will rise rapidly due to the heat generated by the heating element, and the power will be turned off. It is possible to provide an inexpensive and high-performance boiling response device without requiring a special dry firing prevention device and with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an electric kettle according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of its essential parts, and FIG. 3 is a diagram showing a temperature rise curve of the essential parts. 1... Kettle body, 4... Heat sensitive cover (partition member), 5... Pipe, 6... Ferrite (heat sensitive member), 7... Heat generating element.

Claims (1)

[Claims] 1. A heating element is disposed at the bottom of the container, a compartment is provided at the bottom of the container by a partition member separate from the inside of the container, and a constant space is provided between the lower end and the bottom of the compartment to communicate the compartment and the inside of the container. A pipe is disposed with a gap formed therein, and at least a portion of the heating element is brought into contact with a portion of the compartment, and a bottom of the compartment includes:
A boiling response device such as an electric kettle, characterized in that a heat-sensitive member is provided to control energization to the heating element.