JPS60263030A - High-frequency heating device - Google Patents

Abstract

PURPOSE:To prevent deterioration of characteristics of a sensor due to contamination by a method wherein an air discharging path for the high-frequency heating device is bored with an opening and the opening is blockaded by a porous member while a gas sensor is arranged at a position opposing to the opening. CONSTITUTION:A substance to be heated 13 begins to generate water vapor or gas when heating is progressed. The water vapor is discharged by a fan 16 from a ventilating path 17 to the outside of the body of device. The gas sensor 18 is arranged here. The ventilating path 17 is bored with the opening 23 and the opening 23 is blockaded by the porous member 24. The porous member 24 cuts large dirts, such as soot, tar or the like, and delivers only the water vapor or the gas by diffusion to the gas sensor 18 attached to the inside of a small chamber 25 for the sensor. The small chamber 25 for the sensor is a sealed chamber, therefore, the direct blow of dirty exhaust against the gas sensor 18 may be avoided and the sensor gets dirt hardly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high frequency heating device equipped with a sensor, and more particularly to a structure for preventing the sensor from becoming dirty.

Conventional configuration and its problems High-frequency heating devices that automatically terminate heating using sensors have come into widespread practical use in recent years. As an example of such a sensor, a gas sensor that detects steam or gas generated from a heated object has already been put into practical use.

Matsushita's relative humidity sensor 1'Humiceram', absolute humidity sensor 1'Neo Humiceram', Figaro's gas sensor, etc. are applied, and in each case, the sensor chip is indirectly heated to a predetermined temperature using an indirect heater, and steam and various other types of air are heated. It exhibits desired detection characteristics for gas and also burns off dirt on the sensor chip.

Now, in such a gas sensor, it is generally unavoidable that the characteristics change over time due to dirt. In other words, in the early days, BOOKΩ
For example, after several years of use, the sensor resistance may have changed to 600.
This is a phenomenon in which the resistance drops to Ω. This is thought to be due to the sensor not being able to sufficiently release the vapor and gas it has adsorbed, which causes the sensor to gradually change over time.Furthermore, as the oil smoke and tar are burned off by the indirect heater, carbon, which has extremely high heat resistance, is It is presumed that a small amount remains and this adheres to the surface of the sensor chip and affects the characteristics of the sensor.

As described above, conventional gas sensors have had the problem of not being able to sufficiently burn off dirt, resulting in gradual deterioration of their characteristics.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and aims to provide a sensor mounting structure that can significantly reduce deterioration of sensor characteristics caused by dirt.

Structure of the Invention In order to achieve the above object, the high frequency heating device of the present invention has the following features:
A hole is drilled in the ventilation path through which the exhaust gas that ventilates the heating chamber is discharged to the outside of the aircraft, and this is closed off with a porous material.A gas sensor is placed opposite the hole, which eliminates oil smoke and tar. This porous member prevents significant dirt from reaching the gas sensor and prevents deterioration of sensor characteristics.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a perspective view of a high-frequency heating device according to this embodiment. A door body 2 is pivotally supported on the front surface of the main body 1 so as to be freely openable and closable, and an operation panel 3 is provided. On this operation panel 3,
An auto key 4 is provided that performs automatic heating using a sensor.

FIG. 2 is an example of a sensor according to this embodiment, and shows an absolute humidity sensor "Neo Humiceram" manufactured by Matsushita Corporation.The sensor chip 5 has moisture-sensitive characteristics, and is heated to a predetermined temperature by an indirect heater 6. The base 7 supports the sensor chip 5 and the indirect heater 6, and the windproof net 8 removes the influence of wind.

Next, the configuration of such a high frequency heating device will be explained using FIG. 3. Commands input from the auto key 4 on the operation panel 3 are decoded by the control section 9. Then, the control section 9 starts supplying power to the magnetron, which is also the high frequency generating means 1, via the driver 10.

In the heating chamber 12, an object to be heated 13 is placed on a mounting plate 14 and rotated by a motor 15 to improve uneven heating. As the heating progresses, the object to be heated 13
Water vapor and gas begin to be generated. This water vapor is discharged to the outside of the aircraft from a ventilation passage 17 by a fan 16, and a gas sensor 18 is disposed here. Then, it is connected to the control section 9 via the detection circuit 19. The control unit 9 can be realized by a microcomputer.

The ventilation passage 17 discharges the exhaust gas discharged from the exhaust small hole group 20 on the wall surface of the heating chamber to the outside of the aircraft body through the exhaust opening 22 of the exterior 21. The gas sensor 1B is placed in the middle of this ventilation path 17.

FIG. 4 is a detailed sectional view of the ventilation passage 17.

An opening 23 is bored in the ventilation passage 17, and this opening 23 is closed by a porous member 24. The porous member 24 is made of porous ceramic, etc., and cuts off large dirt particles such as oil smoke and tar, and diffuses only steam and gas to the gas sensor 1 installed in the sensor chamber 25.
Deliver it to 8. Since the sensor chamber 25 is a closed room, steam and gas diffuse into the chamber 25 due to concentration differences, and oil smoke, tar, salt, etc. carried by the exhaust air do not enter the chamber 25. This prevents dirty exhaust gas from being blown directly onto the gas sensor 18, making the sensor less likely to get dirty.

FIG. 5 is a graph showing changes over time in the characteristics of the gas sensor. The solid line (I) shows the change over time of the gas sensor installed according to the present invention, and the change is much smaller than the broken line (II) of the conventional gas sensor.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Most of the dirt such as oil smoke and tar emitted by the heated object can be removed by the porous member, and relatively clean air containing steam can be introduced to the gas sensor. Deterioration of sensor characteristics due to this can be suppressed.

(2) The characteristics of a gas sensor are temperature-dependent and change under the influence of wind, but according to the present invention, the wind does not directly hit the sensor, and steam reaches the sensor chamber through diffusion. Therefore, it is not affected by the wind at all.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main body of a high-frequency heating device showing an embodiment of the present invention, FIG. 2 is a partial sectional view of an embodiment of a gas sensor,
FIG. 3 is a block diagram showing the configuration of a high-frequency heating device according to an embodiment of the present invention, FIG. 4 is a detailed sectional view of the same ventilation passage, and FIG. 5 is a graph showing the effects of the present invention. 9...control unit, 11...high frequency generation means,
12... Heating chamber, 13... Heated object, 1
7... Ventilation path, 18... Gas sensor, 2
4...Porous member. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 4 Figure 1

Claims (1)

[Claims] A heating chamber in which an object to be heated is placed, a high frequency generating means coupled to this heating chamber, a control unit controlling power supply to this heating means, and a gas detecting vapor or gas generated from the object to be heated. a sensor; a ventilation means for ventilating the heating chamber;
It consists of a ventilation passage for guiding the exhaust gas discharged by the ventilation means, an opening bored in the ventilation passage, and a porous member for closing the opening, and the gas sensor is positioned opposite to the opening. high frequency heating device.