JPS6329170B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an overtemperature rise prevention device for a high frequency heating device.

Conventional configuration and its problems In recent years, with the spread of microwave ovens, the software of microwave ovens has been improved. For example, there is the use of a meat probe that directly senses the temperature of the food to cook to a predetermined cooking temperature, and the use of sensors such as humidity sensors that detect steam, gas, etc. generated from the food during heating. By using these software sensors, many of them are equipped with microcomputers (hereinafter abbreviated as microcomputers), and conversely, long-time operation, reservation functions, etc. can be easily utilized. As a result of this increase in functionality, there is a hidden danger that the food inside the microwave oven may char and ignite, causing a fire due to malfunctions in the microcontroller or sensors. It is set up. Conventionally, a temperature switch, a temperature fuse, etc. is used to detect a sudden temperature rise on the surface of the oven due to the flame generated inside the oven, and a temperature rise in the exhaust passage sent out from the oven. Measures have been taken to stop the microwave from operating. These overtemperature rise prevention devices are complicated and tend to increase costs.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an inexpensive overheat prevention device that can replace the above-mentioned temperature switch and temperature fuse.

Structure of the Invention In order to achieve the above object, the present invention includes a sensor that detects the temperature of food to be cooked, and a jack that is connected to the sensor and has a rotating function. The structure is such that the contactor that transmits the energy short-circuits both poles of the jack to stop high-frequency oscillation, and is more economical than conventional overtemperature rise prevention devices.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an external perspective view of this embodiment. 1 is a main body of a microwave oven, and a heating chamber 2 is provided within this main body 1. A turntable 3 is provided in the heating chamber 2 in order to make the radio wave distribution more uniform. 4
is a door provided at the opening of the heating chamber 2 so that it can be opened and closed freely;
Reference numeral 5 denotes an operation panel provided on the front side of the main body 1, which includes a display tube for displaying cooking time, output, and time, and a keyboard 6 for setting cooking time, output, etc., and transmitting the settings to the microcomputer. A jack 8 of a sensor 7 for directly sensing the temperature of the finished food is provided on the upper wall of the heating chamber 2 at a position facing the center of the turntable 3.

FIG. 2 shows a configuration diagram of the jack 8. The jack 8 has a cylindrical shape because it needs to synchronize with the rotation of the turntable 3, and is surrounded by a pipe 9 made of thermoplastic resin to ensure sliding and smoothness. It's getting easier. It also insulates the jack 8 from the chassis. An E ring 10 is installed on the jack 8 to prevent the jack 8 from falling.
This is prevented by the ring 10. Jack 8 is electrode 1 that is directly connected to both poles of the thermistor of sensor 7.
1a and 11b, and are separated by an insulator 17. The resistance change of the thermistor of the sensor 7 is caused by the contactors 12a, 12a, which are in contact with the electrodes 11a, 11b.
It is incorporated into the microcontroller through 12b. The contacts 12a and 12b have excellent sliding properties and are made of Ag--C alloy, etc., which is a good electrical conductor so as not to be a load for the rotation of the jack 8. The contacts 12a, 12b and the electrode 11a of the jack 8,
In order to stabilize the contact between the parts 11b, a contact piece 13 made of a spring material is provided to apply a constant contact pressure.
This contact piece 13 also serves to hold the contacts 12a and 12b and to transmit signals to the microcomputer. The contacts 12a, 12b and the electrode 11a of the jack 8,
The contact piece 13 is fixed to the terminal block 14 so that the contact piece 11b contacts at a stable relative position. The terminal block 14 is fixed to a cable cover 15 that prevents radio waves from leaking from the jack 8.

Now, a fire breaks out in the heating chamber 2, the flames directly hit the upper wall of the heating chamber 2, and the temperature of the wall surface of the heating chamber 2 rises rapidly. For this reason, the thermoplastic pipe 9 that supports the jack 8 is softened, deformed, and melted by the heat from the heating chamber 2, and due to the weight of the jack 8,
The pipe 9 is no longer able to maintain its original shape, and the jack 8 moves in the direction indicated by the → mark in FIG. As a result, the relative positional relationship between the contacts 12a, 12b and the electrodes 11a, 11b is disrupted, and the contact 12a short-circuits the electrodes 11a, 11b as shown in FIG. Then, the resistance of the thermistor becomes 0, and the microcomputer determines that some kind of defect has occurred, such as a defect in sensor 7 or a defect in jack 8, and immediately issues a signal to stop the operation, and the power relay 16 is opened and oscillation is stopped. At the same time, the cooling fan 18 is also stopped, air intake into the heating chamber 2 and exhaust from the heating chamber 2 are stopped, and the fire within the heating chamber 2 is extinguished.

In order to operate this structure reliably, contactor 12
The dimension A of a is the dimension B of the insulator 17 of the jack 8.
The amount of thermal deformation C of the pipe 9 is larger than that of the contactor 12.
It is necessary to set it larger than the movement margin D of a.

As another embodiment, operation at a stable temperature can be obtained by using an organic compound material (constant temperature soluble septum) in place of the thermoplastic pipe a.

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

(1) Since the temperature detection configuration for the temperature sensor can also function as an over-temperature rise prevention device, the over-temperature rise prevention device can be abolished, resulting in a significant cost reduction.

(2) The temperature detection configuration uses a low voltage circuit (DC45V or less) that is insulated from the applicable power source, so there is no risk of the lead sensor being short-circuited or electrocuted by heat from a fire, making it extremely safe.

(3) Since the heat deformation temperature is used, the temperature is high and there is no risk of malfunction during normal operation.

[Brief explanation of drawings]

Fig. 1 is an external perspective view of a high-frequency heating device according to an embodiment of the present invention, Fig. 2 is a side cross-sectional view of the jack portion of the device, and Fig. 3 shows the relationship between the jack and contacts of the device. FIG. 4 is an enlarged view of the main parts shown and a circuit diagram of the same device. 1... Main body, 3... Turntable, 7... Sensor, 8... Jack, 9... Pipe, 11a,
11b... Jack electrode, 12a, 12b...
Contactor, 13... Contact piece, 14... Terminal block, 16
...Power relay, 17...Insulator, 18...Cooling fan.

Claims (1)

[Claims] 1. A rotary table in the heating chamber, a sensor that detects the temperature of the food to be cooked, a control means that controls the temperature of the food through the sensor, and a control means that is connected to the sensor in the upper part of the heating chamber, The rotating holding member of the jack is thermally deformed due to a fire that occurs in the heating chamber, and a contactor that transmits a signal from the jack shorts between both electrodes of the jack. death,
A high-frequency heating device configured to stop high-frequency oscillation.