JP2921136B2 - Heating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus such as a cooking oven or a drier for heating while controlling the pressure in a heating chamber.

[0002]

2. Description of the Related Art Conventionally, a method of heating by increasing or decreasing the pressure in a heating chamber of a heating apparatus has been frequently used due to an advantage that a boiling point can be arbitrarily set. For example, in a cooking oven, the application range is wide such that the cooking time can be shortened by pressurizing about 1 atm, or the food is dried at a temperature lower than the coagulation temperature of the protein by reducing the pressure.

A conventional example will be described below with reference to FIG. Opening surface 1a of the heating chamber 1 of the cooking oven shown in FIG.
Is provided with a door 2 that can be freely opened and closed. A gasket 3 is attached to the opening 1a so that the heating chamber 1 is sealed when the door 2 is closed.

A mounting table 4 is provided on the bottom surface 1b of the heating chamber 1.
The weight of the loading table 4 and the food placed on it is directly at the bottom 1b.
Is transmitted to the weight sensor 6 located below the bottom surface 1b of the heating chamber 1 via the support rod 5 that supports the mounting table.

[0005] A sheath heater 7 is provided on the top surface 1c of the heating chamber 1.
Is attached and heats the food. An exhaust port 8 opened in the wall surface of the heating chamber 1 is connected to a vacuum pump and an electromagnetic valve installed outside the body 9, and when the vacuum pump is operated with the heating chamber 1 sealed, the heating chamber 1 is closed. The internal pressure is reduced. A pressure sensor 10 is connected between the exhaust port 8 and the vacuum pump to monitor the degree of pressure reduction.

A keyboard 11 for instructing the control unit 12 to select a cooking category, start cooking, stop cooking, and the like is arranged on the front of the body 9. The control unit 12 is located on the back of the keyboard 11 and incorporates a microcomputer for processing output values of the weight sensor 6 and the pressure sensor 10.

Here, an example in which the user performs reduced pressure cooking will be described. The user first places the food on the mounting table 4 and closes the door 2. When the cooking category is determined by the operation of the keyboard 11 and cooking is started, the weight sensor 6 outputs the weight value of the mounting table 4 and the food to the control unit 12. Control unit 1
2 subtracts a known weight value of the mounting table 4 from the value as a tare, and stores it as a weight value of the food. The cooking time and heating pattern for each cooking category correspond to the food weight, and the control unit 12 determines these heating sequences according to the weight value of the food.

At the same time, the control unit 12 controls the pressure sensor 1
Upon receiving a pressure value from 0, the vacuum pump and the solenoid valve are controlled so as to maintain the inside of the heating chamber 1 at a predetermined pressure.

[0009]

However, in the above configuration, the output of the two sensors is processed by the control unit 12, so that an electronic circuit of the control unit 12 is also required for each sensor. The processing of the weight value is required only at the beginning of cooking, and the processing of the pressure value is required thereafter. That is, the electronic circuit of the pressure sensor 10 is not operating while the weight sensor 6 is operating, and the electronic circuit of the weight sensor 6 is not operating while the pressure sensor 10 is operating. The circuit configuration is complicated and useless. Control unit 1
Not only two but also a sensor mounting structure requires two sensors, resulting in a complicated configuration,
These are disadvantageous in terms of cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heating apparatus which performs a process of treating a weight value of an object to be heated and a control of a pressure in a heating chamber with a simple structure in heating under pressure.

[0011]

In order to achieve the above object, the present invention comprises a heating chamber, a heating means, and a weight detecting means for detecting the weight of an object to be heated. A value proportional to the pressure inside the heating chamber is obtained by a relative comparison between the detected value of the weight of the heated object in the above and the detected value in a state where the pressure inside the heating chamber is increased or decreased from the atmospheric pressure. The heating is controlled using a value proportional to the pressure inside the room.

[0012]

The heating device of the present invention heats the object to be heated on the mounting table by the heating means connected to the heating chamber. The weight of the object to be heated is transmitted to weight detection means located outside the heating chamber via a support rod that supports the mounting table and penetrates the bottom of the heating chamber. In a state in which the inside of the heating chamber is pressurized or decompressed from the atmospheric pressure, not only the wall of the heating chamber but also the support rod receives a pressure proportional to the area of the through portion of the heating chamber. Since the weight detection means detects the stress applied to the support rod as a weight value, a value corresponding to the pressure inside the heating chamber is obtained by a relative comparison between the weight detection value at atmospheric pressure and the weight detection value during pressurization and decompression. You can ask. Therefore, control utilizing information on the weight of the object to be heated and information on the pressure inside the heating chamber can be performed based on the detected value of the weight detecting means.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a heating apparatus according to an embodiment of the present invention.

A door 14 which can be opened and closed is attached to an opening 13a of a heating chamber 13 of the cooking microwave oven shown in FIG. A gasket 15 containing fluorine rubber as a component is attached to the opening surface 13a so that the inside of the heating chamber 13 is sealed when the door 14 is closed. A lock mechanism 16 is provided on the door 14 for the purpose of further ensuring the sealing, and keeps the stress that presses the door 14 against the gasket 15 even after the door 14 is closed unless the user opens the door 14.

An exhaust port 17 opened in the wall of the heating chamber 13
Is connected to a vacuum pump and an electromagnetic valve installed outside the body 18, and when the vacuum pump is operated with the heating chamber 13 sealed, the pressure inside the heating chamber 13 is reduced.

A keyboard 19 for instructing the control unit 20 by the user to select a cooking category, start cooking, stop cooking, and the like is arranged on the front of the main body 19. A control unit 20 incorporating a microcomputer is located on the back of the keyboard 19. Signals for controlling the vacuum pump and the solenoid valve are sent from the control unit 20.

As means for heating the food, a magnetron 21 for performing high-frequency heating is provided. Magnetron 2
1 is connected to the wall surface of the heating chamber 13 via the waveguide 22.

The mounting table 23 located on the bottom surface 13b of the heating chamber
The weight of the food placed on the heating chamber is transmitted to a weight sensor 25 as a weight detecting unit located below the bottom surface 13b of the heating chamber via a support rod 24 supporting the mounting table 23.

FIG. 2 shows a support rod 24 and a weight sensor 25.
The outline of the configuration in the vicinity is shown. It is inevitable that standing waves are generated inside the heating chamber 13 in high-frequency heating, and rotation of the mounting table is generally used as a method for improving heating unevenness.
The rotation of the motor 26 is transmitted to the mounting table 23 via the support rod 24.

The support rod 24 moves freely in the thrust direction and transmits a load to the weight sensor 25. In the radial direction, the rotational motion of the motor 26 coupled to the bottom surface of the heating chamber is transmitted via a gear to function as a rotating shaft.

The support rod 24 penetrates through the bottom surface 13b of the heating chamber. In order to seal the heating chamber 13, it is necessary to seal the penetration. The oil seal 27 was used as a configuration that can most reliably seal the penetration portion. Oil seal 2
7 causes hysteresis in the thrust direction of the support rod 24 and causes an error in the weight detection value. However, the rotation of the support rod 24 by the motor 26 eliminates the hysteresis and the error.

The weight sensor 25 is of a capacitance type in which a pair of gold electrodes facing the surface of the alumina diaphragm are formed and a minute physical change of the diaphragm is converted into a change in capacitance. The capacitance type weight sensor is superior in temperature compensation as compared with a system using a strain gauge, for example, and is suitable for the temperature environment of the heating device. The capacitance is input to the control unit 20 as a frequency via an oscillation circuit.

The pressure inside the heating chamber 13 is uniformly applied to its inner surface. For example, when the inside of the heating chamber 13 is depressurized to a low vacuum of 100 Torr, the inner surface of the heating chamber 13 receives a stress of 1.019 kgf inward per 1 cm ² . This stress is similarly generated in the support rod 24. If the cross-sectional area of the penetrating part of the support rod 24 is 1 cm ² , the weight sensor 2
The load transmitted to 5 is 1.019 kgf subtracted from the actual load.

In other words, if the weight value at atmospheric pressure is known, the apparent weight changes when the same substance is detected during pressurization and decompression, and a pressure difference from atmospheric pressure can be obtained by a relative comparison. .

The detected weight value at atmospheric pressure is W0 (kgf),
The weight detection value during pressure reduction is W1 (kgf), the internal pressure of the heating chamber during pressure reduction is P (Torr), and the cross-sectional area of the support rod 24 is A (cm).
² ), these relationships can be simply expressed by the following equation.

[0026]

(Equation 1)

Here, an example in which the user performs reduced-pressure cooking will be described. The cooking category is thawing cooking under reduced pressure. Taking sashimi of tuna as an example, partial boiling due to uneven heating is not preferred, and it is desirable to heat at a temperature at which boiling does not occur. As long as high-frequency heating is performed, the actual heat source is moisture in the food, and partial boiling due to uneven heating can be prevented by controlling the boiling point of the moisture by reducing the pressure.

FIG. 3 shows a timing chart. When cooking is started, the weight sensor 25 outputs the weight value of the mounting table 23 and the food to the control unit 20. The value W0 is 1.9
kgf. At this time, the vacuum pump has not been operated yet. The control unit 20 uses this value to determine the mounting table 2
The weight value of 1.2 kgf is deducted as tare, and the weight of the food is determined to be 0.7 kgf.

In the case of thawing cooking, the heating time by high frequency is the number of seconds obtained by multiplying the food weight by 1100. In this case, the heating time is 770 seconds.

After detecting the weight value W0 at atmospheric pressure, the control unit 20 operates the vacuum pump. Further, the weight sensor 25 continuously detects the weight value W1, and obtains the pressure value inside the heating chamber from the above equation. However, the sectional area A of the support rod 24 is 0.502 cm ² . Assuming that the control of the boiling point of water by the reduced pressure is 40 ° C., the pressure inside the heating chamber 13 is 55 Torr.
Need to be on the order. In FIG. 3, the detected weight value W1 at the lapse of 120 seconds is 1.42 kgf, and when the pressure value is calculated, it becomes a value close to 55 Torr.

In the above description, the pressure value is calculated by the above equation for the sake of explanation. However, the actual control program does not include a step of converting the pressure value into a value, and the subtraction result of W1 and W0 is calculated as a value proportional to the pressure. And reduced the program capacity. Specifically, in this example, the result of the subtraction is the pressure 55
The heating was started at the point of time when the pressure became -0.48 kgf which means Torr, and the vacuum pump was controlled so that the subtraction result became -0.48 kgf.

Here, the control unit 20 starts high-frequency heating by the oscillation of the magnetron 21. When the above-mentioned heating time of 770 seconds elapses from this point, cooking is completed, and during that time, the control unit 20 controls the vacuum pump so that the inside of the heating chamber 13 becomes 55 Torr.

[0033]

As described above, the following effects can be obtained in the heating apparatus of the present invention.

Since the value proportional to the pressure inside the heating chamber is detected by using the weight detecting means for detecting the weight value of the object to be heated, information on the weight of the object to be heated and the pressure inside the heating chamber is obtained to control the heating means. Or transmit a control signal to the outside. Further, there is no need to add a separate pressure detecting means for pressure detection, so that the configuration is simplified, and the cost can be reduced including mounting and electric circuits.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a heating device according to an embodiment of the present invention including a partially cut-out portion.

FIG. 2 is a sectional view of a main part of a heating device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a timing chart of a heating device in one embodiment of the present invention.

FIG. 4 is an external perspective view of a conventional heating device including a partially cutout portion.

[Description of Signs] 13 Heating chamber 14 Door 15 Gasket 17 Exhaust port 23 Mounting table 24 Support rod 25 Weight sensor

Claims (1)

(57) [Claims] A heating chamber, a door provided at the front of the heating chamber, which can be freely opened and closed, heating means coupled to the heating chamber, and a mounting table inside the heating chamber for mounting an object to be heated, A weight detection unit positioned outside the bottom surface of the heating chamber to detect the weight of the object to be heated; and a support rod that supports the mounting table and penetrates the bottom surface of the heating chamber and transmits the weight of the object to be heated to the weight detection unit. The pressure in the heating chamber is obtained by a relative comparison between the detected value of the weight of the object to be heated in the atmospheric pressure by the weight detecting means and the detected value in a state where the inside of the heating chamber is pressurized or depressurized from the atmospheric pressure. A heating unit having a control unit that obtains a value proportional to the temperature of the object to be heated and performs control using a value proportional to the pressure in the heating chamber and the pressure in the heating chamber.