JPH01302686A - Heat cooker - Google Patents

Abstract

PURPOSE:To provide possibility of proper sensing of gas always and eliminate wasteful operation of a fan by sensing opening of a door after the cooking with heat is finished, and thereupon performing forced ventilation for inside the heating chamber for a minimum required period of time. CONSTITUTION:When oscillation of a magnetron 7 is finished and the cooking with heat finished, a fan 8 for cooling is stopped. Opening of the door by a user is sensed by a door switch 20 as a sensing means, and a signal is sent to a control part 17. This control part 17 sends a drive signal to a fan driving motor 23 to derive the fan again so as to introduce the external air into the heating chamber 2, and the residual gas remaining after taking-out of the subject to be heated S is ventilated forcedly. Even after the door is shut, operation of the fan 8 is continued for a certain period of time, with the forced ventilation still continued, and a stop signal is given to the drive motor 23 by the control part 17 at the point of time when a certain time has passed. This enables proper sensing of gas at all times and eliminates wasteful operation of the fan.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a cooking device equipped with a gas sensor.

(Prior Art) In a heating cooking device such as a microwave oven, gas (steam and smoke) is generated from the object to be heated in the heating chamber.

Some devices are equipped with a gas sensor that detects gas (other gases), and a microcomputer or the like judges and controls the detection output of the gas sensor to automatically cook the heated food.

Conventionally, in the case of such a microwave oven, before the magnetron oscillates when cooking starts, the magnetron cooling fan is operated for a certain period of time (approximately 16 seconds) to blow air into the heating chamber for forced ventilation. The operation is such that gas remaining after cooking is discharged to the outside in advance. This fan operation time is a so-called refresh time for the heating chamber, and residual gas is discharged during this time to ensure detection accuracy of the gas sensor. Thereafter, the magnetron is oscillated to perform a predetermined heating operation.

However, since a forced exhaust time is required before starting the heating cooking, the actual heating cooking time takes a long time, and the time required for forced ventilation as a heating cooking operation is wasted. Further, when the next heating cooking is to be performed immediately after the heating cooking is completed, it is difficult to completely exhaust the residual gas in the heating chamber within the ventilation time. In this case, the next time you heat cooking, you will start cooking before the output level of the gas sensor returns to the pre-cooking state, resulting in overcooking, or in extreme cases, scorching or overcooking. There is a problem that ``variation 2'' occurs due to the

Therefore, a cooking device as disclosed in, for example, Japanese Unexamined Patent Publication No. 63-54522 was invented. In other words, when the door of the heating chamber is opened after heating and cooking is completed, the fan is driven to remove residual gas in the heating chamber. As a result, all residual gas in the heating chamber will be exhausted before the next cooking starts, allowing the gas sensor to properly detect the gas, and making it possible to cook with a stable and good finish.

However, in this type of cooker, the start timing of the forced exhaust operation is only set to be linked to the opening of the door after cooking, and the end timing of the forced exhaust operation is not particularly set. In the example,
A drive motor for a magnetron cooling fan that sends cooling air to the magnetron is connected from a power source via a door switch, and a normally closed door switch is connected in parallel to the door switch. During cooking, a power supply path to the cooling fan drive motor is formed through the door switch, and the drive motor operates. Cooling air is sent to the magnetron, and part of the cooled air is sent into the heating chamber, and part of the gas generated from the object to be heated is exhausted to the outside through the exhaust hole. A gas sensor is provided in the exhaust hole to detect gas generated from the heated object. When the user opens the door of the heating chamber to take out the object to be heated after cooking, the door switch is turned off, but the normally closed door switch connected in parallel with it is closed, so the cooling The fan drive motor continues to be energized. That is, even if the door body is opened, air is blown into the heating chamber, and at this time, gas remaining in the heating chamber is discharged to the outside through the opening of the heating chamber. However, even if all the residual gas is exhausted from the heating chamber, the drive motor of the normally closed door switch continues to be energized, so the cooling fan continues to blow air. When the object to be heated is placed in the heating chamber and the door is closed for the next heating cooking, another door switch is turned on as mentioned above, and when the door is opened after cooking is completed, the normally closed type is activated. door switch closes. In this way, as long as the drive motor of the cooling fan is connected to the power supply, that is, unless the power supply is cut off, one of the door switches is turned on and the drive motor continues to be energized, and is in constant operation. do. Therefore, the drive motor for the cooling fan is operationally wasteful.

(Problem to be Solved by the Invention) As described above, it is possible to eliminate the waste of operation caused by one of the door switches being always on and the cooling fan drive motor continuing to operate, and to solve the problem after heating and cooking. By detecting the opening of the door and performing forced ventilation in the heating chamber for only the minimum amount of time necessary, proper gas detection is always possible, and cooking with stable and good quality is achieved. Improved operability and durability by eliminating wasteful fan operations.”
The purpose of the present invention is to provide a heating cooker that achieves the following objectives.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a gas sensor that detects gas generated from an object to be heated and cooked in a heating chamber of a cooking device main body, and automatically controls heating according to the output of the gas sensor. The eggplant is provided with a means for detecting that a door body for opening and closing the heating chamber is opened after the completion of cooking, and upon receiving a detection signal from the detection means, the heating chamber is forced to open for a preset period of time. This cooking device is characterized by being equipped with forced ventilation means for ventilating and discharging residual gas.

The prescribed time for forced ventilation using the above forced ventilation means is as follows:
Either the setting should be made in accordance with the type of the object to be heated during the cooking process, or the time should be set to continue until the sensor output value of the gas sensor returns to approximately the same value as the value at the start of the cooking process, and the above-mentioned mandatory setting should be made. When the next heating cooking is started during forced ventilation by the ventilation means, forced ventilation continues for the remaining predetermined time of forced ventilation.

(Function) When the detection means detects that the door body for opening and closing the heating chamber has been opened after the completion of cooking, the forced ventilation means operates only for a predetermined period of time in response to this detection signal,
Force the heating chamber to ventilate the remaining gas.

(Example) Hereinafter, an example of the present invention will be applied to a microwave oven and explained based on the drawings. As shown in FIG. 1, numeral 1 in the figure is a cooking device main body consisting of an outer casing, and numeral 2 is a heating chamber consisting of an inner casing provided within the cooking device main body 1. As shown in FIG. This heating chamber 2
A door body (not shown here) is pivotally attached to the front opening of the
It can be opened and closed freely. A turntable 4 provided on the rotating shaft of the drive motor 3 is housed at the bottom of the heating chamber 2.
The object to be heated S is placed thereon and rotated.

An excitation port 5 is opened on the ceiling surface of the heating chamber 2, and a waveguide 6 communicating therewith is mounted. A magnetron 7, which is a high frequency oscillator, is provided at the end of the waveguide 6. Reference numeral 8 denotes a magnetron cooling fan disposed facing away from the magnetron 7. Air guide holes 9 are provided on the wall surface of the cooker main body l adjacent to the fan 8. When driven, external air is guided to the magnetron 7 through the air guide holes 9. In addition, introduction holes 10 are provided in the wall surface of the heating chamber 2 adjacent to the magnetron 7, so that air that has cooled the magnetron 7 is introduced into the heating chamber 2. Above introduction hole 1
Exhaust holes 11 are provided on the wall surface of the heating chamber 2 facing the wall surface on which the heating chamber 2 is provided, and external exhaust holes 12 are provided on the wall surface of the cooking device main body 1 opposing thereto. . These exhaust holes 11... and external exhaust holes 12...
are communicated through an exhaust duct 13.

That is, the air in the heating chamber 2 is discharged and guided to the outside via the exhaust holes 11 . . . , the exhaust duct 13 , and the external exhaust holes 12 . The above exhaust duct 13
A gas sensor 14 is provided. This gas sensor 14
is a well-known method that detects the concentration of gases (all the gases mentioned above, smoke, and alcohol) generated from the heated object S during cooking.

On the other hand, the microwave oven configured in this manner includes an electric circuit as described below. Reference numeral 15 denotes a commercial AC power supply, and a control unit 1 is connected to the power supply 15 via a step-down transformer 16, which includes a microcomputer and its peripheral circuits, and controls the entire microwave oven.
7 is connected.

The control section 17 includes an operation section 181 having dedicated keys for each type of object S to be heated, a display section 19. A door switch 20 that responds to the opening and closing of the door body. Fan drive motor relay 21
．． High voltage transformer relay 22 and the gas sensor 14
is connected. In addition, the power supply 15 has a relay contact 21.
A fan drive motor 23 for driving the magnetron cooling fan 8 is connected through the relay contact 2.
2a to the high voltage transformer 24 and the magnetron 7,
The drive motor 3 of the turntable 4 is connected. The relay contact 21a is connected to the relay 21 and the relay contact 2.
Of course, 2a is interlocked with the relay 22.

Next, the operation of a microwave oven having a configuration similar to that of -2 will be explained. The object to be heated S is accommodated in the heating chamber 2 [7. to start cooking. At this time, the control unit 17 detects that the door body is closed by turning on the door switch 20, and energizes the high voltage transformer relay 22 in response to the cooking start operation. The relay contact 22a is turned on, the magnetron 7 operates in oscillation, high frequency radio waves are supplied into the heating chamber 2, and dielectric heating cooking is started. At the same time, drive motor 3
energized, the turntable 4 rotates to achieve uniform heating. Further, the fan drive motor relay 21 is energized, and this relay contact 21a is turned on to operate the -C fan drive motor 23. The fan 8 is rotatably driven to
...introduces external air and sends cooling air to the magnetron 7 to cool it.

After that, some of the wind flows through the heating chamber 2 through the introduction holes 10...
The gas is sent into the interior, circulates within the interior, and is discharged to the outside via the exhaust duct 13 from the exhaust holes 11 along with a portion of the gas generated from the heated object S. At this time, the gas sensor] 4 detects the discharged gas and outputs the detection signal to the control section 17.

The characteristics of the sensor output change of the gas sensor 14 from the start of cooking, the range output of the magnetron 7, and the operating status of the magnetron cooling fan 8 in response to the change are determined in a second
This will be explained based on the diagram.

That is, when cooking starts, ■o is first detected as a sensor output. Immediately after the start, air is taken into the heating chamber 2 from the outside, and the object to be heated S is not heated, so gas is not generated sufficiently from there, and the gas concentration in the heating chamber 2 decreases. When this decrease in gas concentration reaches its peak, the sensor output detects V.

When the concentration of gas generated from the object to be heated S increases during cooking, the sensor output gradually increases accordingly. When the detected value of the sensor output V changes by a predetermined constant α determined depending on the type of the object to be heated S, that is, when the sensor output increases to α·■, the time to taken up to that point is detected.

Thereafter, the heating operation is completed after operating for a period of time equal to to multiplied by a predetermined constant β that varies depending on the type of the object to be heated S. That is, high voltage transformers 2, 4. The magnetron 7, cooling fan 8, and turntable 4 stop.

As mentioned above, the constants α and β recorded in - differ depending on the type of the object to be heated S. For example, for α, rice is α-0,05, side dishes are a-0,
1, and for root vegetables α-0°15. The reason why the numerical values differ in this way is that the degree of change in gas concentration until a certain predetermined degree of completion is reached varies depending on the object to be heated S, and all of these values are confirmed through experiments. Similarly, β is also set to a numerical value confirmed through experiments.

Also, after reaching α, β and t. The reason for multiplying and matching is to appropriately adjust the continued cooking time after reaching α depending on the amount of the object to be heated S.

For example, if the number of heated objects S increases, t reaches α. will take a long time, so increase the subsequent cooking time,
This eliminates variations in cooking time depending on quantity. Of course,
During this process, the sensor output of the gas sensor 14 increases.

When the oscillation operation of the magnetron 7 ends and the cooking operation ends, the range output becomes zero and the cooling fan 8 stops. The user opens the door without taking out the cooked object S.

When the door switch 20, which is a detection means, detects this and sends a detection signal to the control section 17, the control section 7 sends a drive signal to the fan drive motor 23 to drive the fan 8 again.

'' The two-legged fan 8 introduces outside air into the heating chamber 2 and forcibly ventilates the residual gas remaining after the object to be heated S is taken out from there. Even after the object to be heated S is taken out and the door is closed, the fan 8 continues to operate for a predetermined period of time, and forced ventilation continues. The control unit 17 counts the elapse of a predetermined time and issues a stop F signal to the drive motor 23 of the fan 8 when the predetermined time reaches zero.

In this way, the time period during which the door switch 20 detects the opening of the door body and continues forced ventilation of the heating chamber 2 by the fan 8 after the completion of cooking is set to vary depending on the type of the object to be heated S, for example. In other words, it takes about 16 seconds to warm up rice, and it only takes about 16 seconds to warm up rice, and for dishes with strong smells such as curry and stew.
Since the gas concentration varies depending on the object to be heated, for example, about 30 seconds are required in the case of , the forced ventilation time varies in the range of about 10 to 30 seconds.

Further, in order to set such a time, the sensor output of the gas sensor 14 at the start of cooking may be stored in the control section 17, and the fan 8 may be controlled to be driven until this initial sensor output level is reached. good.

Note that the next heating cooking may be performed immediately after the previous heating cooking is completed. Normally, it takes 5 to 10 seconds to replace the heated object S stored in the heating chamber 2, but if the next heating cooking is to be performed immediately, the forced ventilation time after the previous heating cooking is completed. For the remaining time, forced ventilation will continue when the next cooking starts. By continuing forced ventilation, the sensor output level returns to its original state and optimal cooking is achieved. If forced ventilation is stopped without continuing, for example, ``curry'' that can be heated in 7 to 8 minutes will become 1
It takes 0 to 12 minutes for cooking, and there is a risk that the object to be heated S may burn, so forced ventilation must be continued.

Note that if the forced ventilation operation is performed while the object to be heated S is housed in the heating chamber 2 after heating and cooking is completed, the object to be heated S will cool down.
The fan 8 may be driven for only 0 to 20 seconds, and then the fan 8 may be stopped and the object to be heated S may be taken out from the heating chamber 2 to perform forced ventilation for the remaining time.

The operating characteristics of the first type of microwave oven equipped with a gas sensor are shown in FIG.

That is, at the start of cooking, only the fan 8 is driven and there is no range output. After one hour (approximately 16 seconds) has elapsed, there is a range output for the first time. Similar to the present invention, the sensor output of the gas sensor is initially Vo, and immediately thereafter drops to V. Then, the sensor output increases by α·V during to time, and if the heating action continues for β·to time, cooking ends. When this ends, the range output naturally ends and the fan is stopped. When the user opens the door to take out the object to be heated, the sensor output decreases slightly, and if the user closes the door after removing the object to be heated, the sensor output decreases further. Thereafter, the sensor output decreases, but since it is a natural phenomenon, the decrease phenomenon is extremely smooth and the rate of change is small. Therefore, the sensor output is easily affected by the next heating cooking.

〔Effect of the invention〕

As explained above, according to the present invention, in a device that is equipped with a gas sensor and performs automatic cooking, after the completion of heating cooking, by detecting the opening of the door and performing forced ventilation in the heating chamber for only the necessary minimum time, The present invention has the effect of enabling proper gas detection at all times, achieving stable and well-finished cooking, and eliminating unnecessary fan operations to improve operability and durability.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 shows a heating cooker, a schematic configuration of a certain microwave oven and its electric circuit diagram, FIG. 2 shows an operating characteristic diagram, and FIG. 3 shows a heating cooker. FIG. 2 is an operation characteristic diagram showing a conventional example of the present invention. S: Heated object, 2: Heating chamber, 1: Cooker body, 14: Gas sensor, 20: Detection means (door switch), 8: Forced ventilation means (magnetron cooling ) fan. Applicant's agent Patent attorney Takehiko Suzue

Claims (4)

[Claims] (1) A cooking device body equipped with a heating chamber for cooking an object to be heated, and a gas sensor for detecting gas generated from an object to be heated and cooked in the heating chamber of the cooking device main body, In a device that automatically controls heating according to the output of a gas sensor, there is provided a detection means for detecting that a door body for opening and closing the heating chamber is opened after the completion of cooking, and a detection signal from the detection means is received. A heating cooking device characterized by comprising forced ventilation means for forcedly ventilating the heating chamber only for a predetermined period of time and exhausting residual gas. (2) The predetermined time for forced ventilation using the above forced ventilation means is:
2. The heating cooking device according to claim 1, wherein settings are made in accordance with the type of the object to be heated in the heating cooking. (3) The predetermined time for forced ventilation using the above forced ventilation means is:
The heating cooking device according to claim 1, characterized in that a time period is set for continuing until the value of the sensor output of the gas sensor returns to approximately the same value as the value at the time of starting the heating cooking. (4) When the next heating cooking is started during forced ventilation by the forced ventilation means, forced ventilation is continued for the remaining predetermined time of forced ventilation. Heating cooker as described in section.