JPH02178525A - Cooking oven - Google Patents

Abstract

PURPOSE:To eliminate the irregularity in the accuracy of steam detection due to the difference in the position where food is located, by providing two or more vents on the ceiling of a heating compartment to vent steam, and a common guide duct which leads the steam from the two or more vents to a pyroelectric element. CONSTITUTION:Three vents 7a-7c each consisting of punched holes are provided on a ceiling 1a of a heating compartment 1, a duct 8 that connects to the vents is provided above the ceiling 1a, and one end of the duct 8 is extended up to nearly the upper portion of a fan 6. The high temperature steam generated by an item 3 to be heated rises up to the coiling 1a and enters the duct 8 through the vents 7a-7c, and comes into contact with a pyroelectric element 2 located inside the duct 8 almost above the cooling fan 6 to give off the thermal energy to the pyroelectric element 2. By this constitution described above, as the steam gathered in the duct scarcely changes in quantity, the irregularity in the detecting accuracy due to the difference in the food location can be considerably eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cooking device that detects the finished state of heating food using a pyroelectric element that generates voltage in response to the heat of high-temperature steam generated from the food. In particular, it relates to the configuration of a vent for extracting steam from a heating chamber.

2. Description of the Related Art A cooking device (for example, a microwave oven) has been proposed that detects the doneness of food using a pyroelectric element that generates a voltage in response to the heat of steam generated from the food. In this case, unlike in the case of humidity sensors that are commonly used in the past, it is necessary to apply steam having sufficient thermal energy to the pyroelectric element. This kind of steam begins to generate rapidly just before the boiling point of water, and rises upwards in the heating chamber on the updraft. Therefore, installing a vent on the ceiling of the heating chamber to take out the steam will improve its detection ability. It is possible to realize a high detection system. FIG. 2 shows an example of such a configuration, in which the vent 4 is provided approximately at the center of the ceiling surface 1a of the heating chamber 1. An object to be heated 3 (food) placed in a heating chamber 1 is dielectrically heated by 2450 MHz microwaves generated by a magnetron 5. The fan 6 is provided to cool the magnetron 5, a high voltage transformer (not shown) that supplies high voltage to the magnetron 5, and the like.

When the temperature of the heated object 3 rises and reaches a temperature close to the boiling point of water, which is generally contained in a large amount in food, a large amount of high-temperature steam is generated, forming an upward airflow and flowing toward the ceiling of the heating chamber 1. It rises through the vent hole 4 and hits the pyroelectric element 2. The steam that hits the pyroelectric element 2 condenses here and gives the pyroelectric element 2 a large amount of thermal energy, mainly latent heat, so the pyroelectric element 2 generates a voltage, and the change in voltage causes the object to be heated to 3 finish (heated!! 3) can be detected.

Problems to be Solved by the Invention However, in the case of the above configuration, the detection output is maximum when the food (the object to be heated) is placed at the center, directly below the vent from which the steam is taken out, and the detection output decreases when it is placed at the edge. Because the amount of steam that can be taken out varies greatly depending on the position where the product is placed, it has been difficult to accurately detect the finished product.

On the other hand, the pyroelectric element generates voltage on the premise that it receives a large amount of energy mainly from latent heat generated by high-temperature steam condensing on the surface of the element. Therefore, if the pyroelectric element becomes hotter than the steam itself, this mechanism of transferring and receiving thermal energy will no longer work, making steam detection impossible. In the case of the above configuration, the temperature rise in the heating chamber 1, especially near the ceiling surface 1a, where the pyroelectric element is arranged, is inevitable due to its function as a heating cooker, and the pyroelectric element is brought to a low temperature at which steam can be detected. It was very difficult to keep it.

The present invention aims to solve these problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the cooking heater of the present invention includes a plurality of vents for taking out steam on the ceiling surface of the heating chamber, and a burner for directing the steam taken out from the plurality of vents. It has a configuration consisting of a common guide leading to the electronic elements.

Function The present invention has the above-mentioned configuration, and since a vent is provided on the ceiling surface, high-temperature steam can be extracted efficiently, and the generated steam can be applied to the pyroelectric element regardless of the position of the object to be heated (food). As a result, variations in detection accuracy depending on the position of food can be significantly reduced.

Furthermore, since the extracted steam can be guided through a duct and brought, for example, to the vicinity of a cooling fan, the pyroelectric element can be kept at a low temperature and detection sensitivity can be maintained.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, ventilation lowers a, 7b, and 7C consisting of three punched holes are provided on the ceiling surface 1a of a heating chamber 1, and a duct 8 connected to these ventilation lowers a, 7b, and 7c is provided on the ceiling surface 1a. One end thereof extends almost to the top of the cooling fan 6.

The high temperature steam generated by the heated object 3 rises and reaches the ceiling surface 1.
a, and is guided into the duct 8 through the ventilation lowers a, 7b, and 7c. Furthermore, this steam passes through the duct 8 and hits the pyroelectric element 2 provided in a part of the duct 8 almost above the cooling fan 6, and imparts its thermal energy to the pyroelectric element 2.

According to the above configuration, steam is taken out by the plurality of ventilation lowers a 7b7c provided at positions apart from each other on the ceiling surface 1a, and after being collected in the common duct 8, it is applied to the pyroelectric element 2. Therefore, even if the amount of steam that can be taken out from each vent changes depending on the position where the object to be heated 3 is placed, the amount of steam that collects in the common duct 8 will hardly change, and therefore the amount of steam that can be taken out from the common duct 8 will change. Variations in detection accuracy due to differences in position can be significantly reduced.

Furthermore, in the case of this configuration, the pyroelectric element 2 is located near the cooling fan 6, and there is no temperature rise like that on the ceiling surface la of the heating chamber 1, so the sensitivity due to the temperature rise of the pyroelectric element 2 is reduced. The pyroelectric element 2 is connected by the duct 8 so that no deterioration occurs.
It also has the effect of being able to place it in the optimal position.

Effects of the Invention As described above, the present invention provides a heating cooker that detects the finish of heating food by exposing high-temperature steam generated from the food to a pyroelectric element, and the present invention provides a plurality of ventilation holes in the ceiling of the heating chamber. (1) Steam generated from the object to be heated (food) can be extracted stably regardless of the position where the food is placed; Variations in detection accuracy due to differences in food placement positions can be significantly reduced.

(2) Since the steam taken out from the vent installed on the ceiling is guided to the duct, the pyroelectric element can be placed near a cooling fan to suppress temperature rise and maintain high sensitivity. Even when the temperature rise in the room is large, the sensitivity of finish detection can be kept extremely high.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional example. 1... Heating chamber, 2... Pyroelectric element, 4...
...Vent, 6...Cooling fan, 7a,
7b, 7c...Vent, 8...Duct. Name of agent: Patent attorney Shigetaka Awano Haka1 person 1 -m-
En 11 Ship 2-・-1 Electric element 6-・Yumikama Button Faso

Claims (1)

[Claims] a heating chamber, a plurality of vents formed at separate locations on a ceiling wall surface of the heating chamber, for guiding steam generated from an object to be heated in the heating chamber from the heating chamber; A heating cooker having a duct common to a plurality of vents and a pyroelectric element sensitive to the heat of steam guided by the duct.