JPS61250421A - Steam oven - Google Patents

Abstract

PURPOSE:To stabilize the quality, to reduce the number of component parts and to improve the safety of a boiler by printing and baking a resistor unit having the Curie point in a temperature range under the condition of burning an empty boiler as well as a positive temperature coefficient onto a ceramic container. CONSTITUTION:In a space between the unit casing 11 and the oven casing 12, a boiler 15 is provided to supply steam into the oven casing through a pipe 14. The boiler 15 comprises a corrosion-resistant, electrically insulating ceramic container 16 onto whose outer surface a resistor unit 17 having a positive temperature coefficient is printed and baked. The boiler 15 has the Curie point in a temperature range under the condition of heating when it is empty, and when the Curie point is exceeded, the resistance is radically increased in a logarithmic proportion. By this constitution, the construction of the boiler can be simplified and the cost can significantly be reduced. Further, as the electric current is limited when the boiler is heated without water by rapidly increasing resistance of the resistor, the degradation of safety due to the overheating can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a steam oven equipped with a steam function for use in general households.

BACKGROUND OF THE INVENTION A conventional steam oven of this type is disclosed in, for example, Japanese Patent Application Laid-open No. 54
As shown in Japanese Patent No. 46866, the structure was as shown in FIGS. 4 and 6.

That is, a boiler 2 provided for supplying steam into an oven chamber 1 has a corrosion-resistant metal container 3 such as stainless steel, and a powder having electrical insulation properties between a resistor 4 and a metal vibro. The sheathed heater 7 is constructed by brazing the sheathed heater 7 with a brazing material 8.

Problems to be Solved by the Invention However, in such a conventional configuration, in order to electrically insulate the metal container 3 of the boiler 2 that generates steam and ensure safety, electrical insulation is applied in advance. The sheathed heater 7 must be joined to the metal container 3 via the brazing material 8 using a brazing machine.
In order to prevent unsafe conditions due to abnormal overheating in the event of dry firing due to no water supply, the system must be equipped with a protector (not shown) such as a thermostat or temperature fuse. Therefore, the number of parts constituting the boiler 2 increases, which is disadvantageous in terms of cost.
A gap is created between the soldering material 8 and
As a result, heat conduction deteriorates, causing abnormal heat generation locally, and furthermore, the presence or absence of voids cannot be easily determined visually, making it impossible to improve yield.

The present invention solves these problems, and aims to provide a steam oven equipped with a boiler that has stable quality, a small number of parts, and is highly safe.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a resistor having a positive temperature coefficient and a Curie point in the temperature range of the dry firing state in a ceramic container having corrosion resistance and electrical insulation properties. The boiler was constructed by printing and baking the body.

It is very advantageous in terms of operation, and printing of resistors on ceramic containers can be easily done using existing printing technology, and even if printing defects occur during the process, it is easy to visually determine whether the resistor is good or bad. Therefore, it is possible to obtain a boiler of excellent quality, and furthermore, when the boiler becomes dry-fired, the resistance value of the resistor increases rapidly, which limits the current and prevents overheating.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings. In FIGS. 1 and 2, 11 is a steam oven main body, and an oven compartment 12 is provided inside this main body 11, and a door 13 is provided at the front opening of this oven compartment 12 so as to be openable and closable. There is. Further, a boiler 16 is provided in the gap between the main body 11 and the oven chamber 12 to supply steam to the inside of the oven chamber 12 via a pipe 14. This boiler 16 generates steam and supplies this steam to the inside of the oven chamber 12.The boiler 16 is also used to apply a positive temperature to the outer surface of the ceramic container 16, which has corrosion resistance and electrical insulation properties. It is constructed by printing and baking the resistor 17 having the coefficient.

As shown in FIG. 3, the resistor 17 has a Curie point To in the dry firing temperature range,
When the resistance value exceeds o, the resistance value rapidly increases on a logarithmic scale.

On the other hand, water is supplied to the boiler 16 from a cartridge-type water tank 19 via a water receiver 18, and the water tank 19 can be attached or removed by operating a door 20.

By adopting such a configuration, the number of parts for configuring the boiler 16 can be significantly reduced, so
It can be obtained at a very low cost, and since the resistor 17 is applied uniformly to the ceramic container 16, the heat distribution becomes uniform and the resistor 17 has a Curie point Tc in the baking temperature region. Therefore, when the water supply to the boiler 16 is cut off and the boiler 16 becomes dry-fired, the resistance value of the resistor 17 rapidly increases and limits the current, making it possible to prevent overheating. The steam oven is equipped with a boiler 16 that is stable and highly safe.

Effects of the Invention As is clear from the above embodiments, the steam oven of the present invention includes a boiler for generating steam in a ceramic container having corrosion resistance and electrical insulation and having a Curie point in the temperature range of the dry firing state. Since it is constructed by printing and baking a resistor with a positive temperature coefficient, the boiler structure is simplified and can be obtained at an extremely low cost. Since the resistance value of the resistor increases rapidly to limit the current, it is possible to prevent a decrease in safety due to overheating.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of a boiler in a steam oven showing an embodiment of the present invention, Fig. 2 is a cutaway perspective view showing the internal structure of the same steam oven, and Fig. 3 shows the temperature and resistance value of a resistor. FIG. 4 is an enlarged sectional view of a boiler in a conventional steam oven, and FIG. 6 is a cutaway perspective view showing the internal structure of the steam oven. 11... Steam oven body, 12...
・Oven storage, 16...Boiler, 16...
・Ceramic container, 17...Resistor, 19.
...Water tank. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 15-m-Boiler Figure 2 Figure 3 r' Humidity. Figure 5

Claims (1)

[Claims] It includes a steam oven main body, an oven chamber provided in the main body, a boiler that supplies steam to the oven chamber, and a water supply tank that supplies water to the boiler, and the boiler has corrosion resistance and electrical insulation properties. A steam oven constructed by printing and baking a resistor having a positive temperature coefficient and a Curie point in the temperature range of the dry baking state on a ceramic container having