JPS5919245B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a high-frequency heating device that uses a humidity sensor to detect exhaust gas from a heating chamber and controls the supply of high-frequency waves.
The purpose is to improve humidity detection ability.

Conventionally, a high-frequency heating device consists of a heating chamber for storing an object to be heated, a door for putting in and taking out an object to be heated, a means for supplying high-frequency power, and an outer shell.The heating time is set by a timer,
Or, it was common to control the supply of high frequency waves by setting the heating temperature using a temperature sensor.

The disadvantage of these high-frequency heating devices is that the timer type relies on intuition to set the heating time, resulting in variations in the degree of heating of the object to be heated. Inserting the probe to be measured into the object to be heated was a time-consuming process. Recently, in order to solve the above-mentioned drawbacks, high-frequency heating apparatuses have been in the spotlight, which use a humidity sensor to detect steam emitted from an object to be heated and control the supply of high-frequency waves. As shown in FIG. 1, the configuration of these high-frequency heating devices is such that when the temperature of the object to be heated 1 reaches 100° C. and steam exits into the heating chamber 2, the relative humidity within the heating chamber 2 increases. The highly humid air exits from the exhaust hole 3, passes through the exhaust passage 4, and is exhausted to the outside of the high-frequency coating device. A humidity sensor 5 whose resistance value changes depending on the relative humidity is installed in this exhaust passage. Based on the change in the resistance value of this humidity sensor, it is detected that the object to be heated has been heated to 100°C, and the supply of high frequency is started. It's in control. The conventional heating device described above has a drawback that when the ambient temperature is high, the amount of change in the relative humidity of the exhaust gas from the heating chamber becomes small, making it impossible to detect that the temperature of the object to be heated has reached 100°C.

The reason for this will be explained below. FIG. 2 shows the relationship between the temperature of the air, the weight of water contained per unit of air, and the relative humidity. After the temperature of the heated object reaches 100° C., the amount of water vapor emanating from the heated object per unit time is proportional to the high frequency output, but it hardly changes depending on the load amount. If the ambient temperature rises and the temperature inside the heating chamber reaches, for example, 50°C, the relative humidity will change from 25% to 50% at 40°C and the amount of change will be 25%, but it will change from 14Cf6 to 28%.D The amount of change is 14%. The present invention solves the above-mentioned conventional drawbacks, and will be described below based on embodiments thereof.

In Fig. 3, 1 is an object to be heated, 2 is a heating chamber that stores the object to be heated 1, 6 is a door for putting in and taking out the object to be heated, T is a waveguide that guides high frequency waves into the heating chamber 2, and 8 is an electric waveguide. A fan motor for cooling parts, etc., 9 is an intake hole, 3 is a heating chamber 2
4 is an exhaust passage, and 5 is a humidity sensor whose resistance value changes depending on the relative humidity.

If high frequency waves are supplied in the above configuration, the object to be heated will be heated by a single force, and after a certain period of time, the object to be heated will reach 100° C. and will emit water vapor, which will lower the humidity in the heating chamber. The air in the heating chamber passes through the exhaust hole 3 and the exhaust passage 4 and is exhausted to the outside of the high-frequency heating device. On the other hand, cooling air for cooling electrical components and the like is sucked in through the exhaust hole 9, rises along the outer wall of the heating chamber 2, passes along the outer wall of the exhaust passage 4, and is sucked into the fan motor 8. When the cooling air passes over the exhaust passage 4, the exhaust passage 4 is cooled, and the exhaust from the heating chamber 2 is also cooled, so that the relative humidity of the exhaust from the heating chamber is increased. For example, the temperature in the heating chamber before the heated object 1 reaches 100°C is 50°C.
Relative humidity: 30%, temperature after reaching 100℃: 60℃
Assuming that the relative humidity is 50%, the amount of change in relative humidity is only 20% when the present invention is not implemented.

If the present invention is implemented and the exhaust gas from the heating chamber is cooled by 6 degrees, the relative humidity before reaching 100°C is 43q6,
The relative humidity after reaching 100℃ is 70I! ), and the amount of change in relative humidity is 27%. The amount of change in relative humidity is detected by the humidity sensor 9, and the supply of high frequency is controlled. Therefore, the amount of change in humidity is significantly increased by the present invention.

Also, in another embodiment in which a cooling air is introduced into the exhaust passage instead of providing a cooling means for the exhaust passage, young fruits similar to those of the above embodiment can be obtained.

The operation will be explained below. The cooling air introduced into the exhaust passage is mixed with the exhaust gas from the heating chamber, and its temperature is lowered, thereby increasing the change in relative humidity. For example, the temperature of the exhaust air from the heating chamber before the temperature of the object to be heated 1 reaches 100°C is 50°C, the relative humidity is 30%, the temperature of the exhaust air after reaching 100°C is 60°C, the relative humidity is ~50%, and the temperature is 20°C. Assuming that cooling air with a relative humidity of 60% °C is introduced into the exhaust passage and mixed with the exhaust air from the heating chamber at a volume ratio of 1:1, the temperature of the mixed object 1 before it reaches 100 °C is The temperature of the exhaust gas is 34°C, 52%, and after reaching 100°C, the temperature of the exhaust gas is 39°C, 89%, and the amount of change in relative humidity is 37%.

On the other hand, when the present invention is not implemented, the amount of change in relative humidity is 2
Since it is only 0%, the amount of change in relative humidity increases significantly by implementing the present invention. As described above, according to the present invention, it is possible to increase the amount of change in relative humidity, and it is possible to detect that the temperature of the heated object has reached 100° C. even under adverse conditions of high ambient temperature.

Also, since the change in the resistance value of the humidity sensor 5 increases,
This eliminates the need for a structure to shield the humidity detection circuit, which was required in the past, since high frequencies penetrate into the humidity detection circuit and cause noise, causing malfunctions, thereby reducing costs.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional high-frequency heating device;
The figure is an psychrometric diagram showing the relationship between air temperature and humidity, and FIG. 3 is a perspective view of an embodiment of the present invention. 2... Heating chamber, 3... Exhaust hole, 4...
... Exhaust passage, 5 ... Humidity sensor, 8.
...Quan motor.

Claims (1)

[Claims] 1. A high-frequency heating device configured to control the supply of high-frequency waves by detecting exhaust gas from a heating chamber using a humidity sensor, and further comprising means for cooling an exhaust passage leading from the heating chamber to the humidity sensor.