JPH0953828A - Cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable quick judgment of freezing or non-freezing of food without drying thereof. SOLUTION: A moisture sensor 24 has a closed type first detector 31 and an open type second moisture detector 33. In a duct 20, the second moisture detector 33 is arranged at a part where it is higher in temperature than the first moisture detector 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating cooker provided with a judging means for judging whether food is frozen or non-frozen.

[0002]

Conventionally, as this kind of cooking device, there is one having a structure disclosed in Japanese Patent Laid-Open No. 2-146416. In this, food is placed in the cooking chamber and the magnetron as a heating means is driven to heat the food, and at that time, the gas generation amount in the cooking chamber is detected by the gas sensor provided in the exhaust passage. Based on the detection status (occurrence status), it is determined whether or not the food is frozen. The gas sensor is configured so that the output (voltage) level becomes lower as the amount of gas (humidity) increases, and is a so-called relative humidity sensor type. In this case, the detection status (output status) of the gas sensor is as shown in FIG.

That is, the characteristic curve A shows the gas detection situation in the case of frozen food, and the characteristic curve B shows the gas detection situation in the case of non-frozen food. Both of the characteristic lines A and B show a characteristic that the output of the gas sensor gradually increases, reaches a peak of an increase at a certain point, and then decreases. The difference between the characteristic lines A and B is that the degree of downward change is Be looked at. Therefore, the degree of downward change from the peak time is always detected,
Whether the product is frozen or not is determined based on the degree of change.

However, in the above-mentioned prior art, the output of each gas sensor in the case of frozen foods and non-frozen foods shows the characteristic of increasing initially, and the difference between these outputs is the increase in output. Since it does not appear that it does not wait until the descending characteristic after the peak, there is a problem that it takes time to determine whether it is frozen or not. In addition, in both frozen and non-frozen cases, the output of the gas sensor rises and then falls, showing basically the same characteristics.Therefore, if the output of the gas sensor fluctuates slightly, the determination may become unclear. There is a problem that it is slightly inferior in sex. As a countermeasure, it is conceivable to drive the fan and forcibly supply the air (humidity) in the cooking chamber to the gas sensor part to speed up the rise of the sensor output. There is a risk that it will be too dry due to the wind of the fan.

The present invention has been made in view of the above circumstances, and an object thereof is to quickly determine whether a food is frozen or unfrozen without drying the food, and further, the reliability of the determination is increased. Providing a heating cooker.

[0006]

The cooking device according to the present invention comprises:
A heating and cooking chamber in which food is placed, a heating means for heating the food, a duct leading from the heating and cooking chamber to the outside, a closed first humidity detecting element and an open second humidity detecting element A humidity sensor arranged so that the second humidity detecting element is located at a position where the temperature of the second humidity detecting element is higher than that of the first humidity detecting element, and the heating means. And a determination unit that determines whether the food is frozen or non-frozen based on the detection output from the humidity sensor at the time of heating.

In this structure, the air and food in the cooking chamber are heated during the heating by the heating means. Then, the food product generates steam depending on its state. The water vapor and the heated air flow into the duct during natural convection in the cooking chamber, and the first of the humidity sensor
And contact the second humidity detecting element. At this time, the second
Since the humidity detection element of is located at a position where the temperature is higher than that of the first humidity detection element, the sensor output shows a characteristic of increasing in one of frozen food and non-frozen food,
On the other hand, it exhibits a falling characteristic. That is,
The frozen and non-frozen foods have opposite change characteristics, and as a result, frozen / non-frozen foods can be quickly determined, and the reliability of the determination is high. in this case,
Since the air in the cooking chamber is not forcibly blown against the humidity sensor by the fan, the food will not be dried.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. First,
2 and 3 showing a schematic overall configuration of a microwave oven having a toaster function and a grill cooking function, a microwave oven main body 1
Is formed by arranging an inner box 3 inside an outer box 2, and the inside of the inner box 3 is a heating cooking chamber 4 for accommodating and arranging foods for cooking. A machine room 5 is provided on the right side of the heating and cooking chamber 4, and inside the machine room 5, a magnetron 6 as a heating means, a cooling fan device 7 for cooling the magnetron 6, and an outside air to the heating and cooking room 4 are provided. A blower fan device 8 for supplying, a control circuit unit 9, and the like are provided. The cooling fan device 7 is composed of a fan 7a and a fan motor 7b, and the blower fan device 8 is a fan 8a.
And a fan motor 8b.

Further, a door 10 for opening and closing the heating and cooking chamber 4 is provided on the front surface of the range main body 1, and an operation panel 11 is provided. The operation panel 11 is provided with an operation section 12 provided with various switches and a display section 13 provided with various indicators.

Upper heaters 14 and 15 (see FIG. 1) as heating means are arranged on the ceiling plate portion of the inner box 3.
A lower heater 16 is provided on the outer bottom surface of the bottom plate portion.
Further, an RT motor 17 is disposed below the bottom plate portion, and its rotation shaft 17a penetrates through the bottom plate portion and projects into the heating and cooking chamber 4, and the projection portion also serves as a rotating plate. A net 18 is connected.

Further, the inner box 3 which is the inner wall of the heating and cooking chamber 4
An exhaust port 4a composed of a large number of holes is formed on the upper right side of the back plate portion, and an exhaust port 19 composed of a large number of holes is also formed in a portion of the outer box 2 facing the exhaust port 4a. An exhaust duct 20 is arranged so as to connect the ports 4a and 19 to each other.

As shown in FIG. 6, the duct 20 is made of a metal plate and has a rectangular tube shape. Further, as shown in FIGS. 1, 7 and 8, the right side plate portion 20 of the duct 20 is
A circular sensor placement hole 21 is formed in a, and is punched out to a portion on the heating cooking chamber 4 side (inner box 3 side) among the portions diagonally opposed to each other with the sensor placement hole 21 sandwiched therebetween. The insertion hole 22 is formed by molding, and the screw hole 23 is formed in the outer side (outer box 2 side).

A humidity sensor 24 is placed in the sensor placement hole 21 and attached to the duct 20. Sensor case 25 which is an outer case of the humidity sensor 24
Is a circular collar 26 around the circular recesses 26a, 27a.
circular case plate 2 made of metal having b and 27b respectively
6 and 27 are attached to each other. The sensor case 25 has a reference sensor section 28 and a detection sensor section 29 attached thereto. Reference sensor unit 28
Is configured by arranging a first humidity detecting element 31 formed of a thermistor in a sealed case portion 30 in which dry air is sealed, and the detection sensor portion 29 has a communication hole portion 32a,
A second humidity detecting element 33, which is a thermistor, is arranged in the open case portion 32 in which 32a is formed. The tip portion of the closed case portion 30 and the tip portion of the open case portion 32 (portions in which the communication holes 32a, 32a are formed) project from the case plate 26 to the outside.

The sensor case 25 is provided with an insertion piece portion 34 and a screw attachment piece portion 35 at both ends in the direction orthogonal to the arrangement direction of the reference sensor portion 28 and the detection sensor portion 29. Further, the cable 36 is led out from the reference sensor unit 28 side. Thus, in the humidity sensor 24 having such a configuration, the insertion piece portion 34 is inserted and engaged with the insertion hole portion 22 of the duct 20, and the attachment piece portion 35 is provided.
The duct 20 by screwing the screw into the screw hole 23.
It is mounted and fixed in a surface contact state. In this case, the second humidity detection element 33 of the detection sensor unit 29 is located closer to the cooking chamber 4 side than the first humidity detection element 31 of the reference sensor unit 28, and the vertical relationship is the second. The humidity detecting element 33 is located below the first humidity detecting element 31. Then, the cable 36 is in a form led out from a portion of the sensor case 25 that is far from the cooking chamber 4.

The humidity sensor 24 detects the humidity by the first and second humidity detecting elements 31, 33.
Is heated to about 200 ° C. At this time, the sealed first humidity detecting element 31 of the reference sensor unit 28
Is sealed in dry air, it radiates a certain amount of heat. On the other hand, in the open-type second humidity detecting element 33 in the detection sensor unit 29, the amount of heat radiation varies depending on the amount of moisture (absolute humidity) contained in the air flowing into the open case unit 32. It is configured.

The first and second humidity detecting elements 30 and 31 are the same as the humidity sensor 2 shown in FIG.
4 is provided in the humidity detection circuit 37 that constitutes a part of the circuit 4. The humidity detecting circuit 37 bridges the first and second humidity detecting elements 31 and 33 and the resistors 39 and 40 between both terminals of the DC power source 38, and also connects the first and second humidity detecting elements 31 and 33. Intermediate connection point P
1 and the intermediate connection point P2 of the resistors 39 and 40 are connected to the amplifier 4
It is configured to be connected to the two input terminals 41a and 41b. With this configuration, the amplifier 41
The output terminal 41c outputs the detection signal of the voltage level corresponding to the absolute humidity of the air to be detected.

On the other hand, FIG. 9 is a diagram showing an electrical configuration of the microwave oven in a combination of functional blocks. In FIG. 9, a control circuit 42 composed of a microcomputer or the like has a function of controlling the entire heating and cooking operation, and stores a control program for the above function in its internal memory. The control circuit 42 is configured to have a function as a determination unit. The control circuit 42 includes the magnetron 6, the fan motor 7b of the cooling fan device 7, and the fan motor 8 of the blower fan device 8.
b, display unit 13, upper heaters 14 and 15, and lower heater 1
6. The RT motor 17 is drive-controlled via the drive circuit 43.

Next, the operation of the above-described structure, particularly the operation when performing so-called "toast cooking" for heating and cooking bread, will be described with reference to FIG. This figure 1
2 schematically shows the control content of “toast cooking” in the control program stored in the control circuit 42. This control program is executed by designating “toast cooking” by operating the cooking menu switch 12a of the operation unit 12 and operating the start switch 12b, and the bread is placed on the rotary net 18. Then, when the above switch operation is performed, the control device 42
First, in step S1, the cleaning operation is executed by operating the fan motor 8b of the blower fan device 8 for 5 seconds (after 5 seconds, the operation of the fan motor 8b is stopped).

Thereafter, the process goes to step S2 to energize the upper and lower heaters 14, 15 and 16. As a result, the bread in the cooking chamber 4 is heated. In this case, since the blower fan device 8 is stopped, natural convection occurs in the heating cooking chamber 4, and a part of the natural convection flows into the duct 20. Therefore, the air comes into contact with the second humidity detecting element 33 of the humidity sensor 24. In this case, the second humidity detecting element 33 is located closer to the heating cooking chamber 4 side than the first humidity detecting element 31 and is therefore located at a portion having a temperature higher than that of the first humidity detecting element 31. Become.

Here, the humidity sensor 24 in such a temperature condition outputs (output of the amplifier 41) Vout.
However, it was found that the temperature changes depending on the state of the bread to be heated, as shown in FIG. That is, when the bread is unfrozen, for example, in a room temperature state (hereinafter referred to as room temperature bread), the sensor output Vout gradually increases from the start of heating, as indicated by the characteristic line R. Also,
When the bread is frozen (hereinafter referred to as frozen bread), the output Vout gradually decreases from the start of heating as indicated by the characteristic line Q. It is speculated that the reason for showing the characteristic like the characteristic line Q is that in the case of frozen bread, the inside of the cooking chamber 4 dries because the water does not evaporate immediately when heated.

After step S2, step S
Move to 3 and start time counting. The parameter of the count time is Tα. Next, in step S4, reading of the output of the humidity sensor 24 (output of the amplifier 41) Vout is started.

In step S5, the count time T
The minimum value Vmin of the output Vout is detected until α reaches 30 seconds. When this 30 seconds has elapsed, the process proceeds to step S6, and the output change amount Δd is calculated. This output change amount Δd is represented by dΔ = Vout−Vmin.

After this, step S7 and step S8
Then, it is determined whether the output variation Δd exceeds “−0.1” by the time Tα exceeds “80 seconds”, and if it exceeds, it is determined to be room temperature bread (step S10). In addition, the output variation Δd does not exceed “−0.1” and Tα
When “80 seconds” has elapsed, the process proceeds to step S11 and step S12, and it is determined whether the output variation Δd exceeds “−0.1” by the time Tα exceeds “100 seconds”. If it exceeds, it is determined that the temperature is in the intermediate state between room temperature bread and frozen bread (hereinafter, intermediate bread) (step S13). Then, the output change amount Δd is “−
If Tα exceeds “100 seconds” without exceeding 0.1 ”, the process proceeds to step S14 and it is determined that the bread is frozen (step S14).

After this, the process proceeds to step S15, and the cooking time is decided. In this case, the cooking time is set to be longer in the order of room temperature bread, intermediate bread, and frozen bread. After that, when it is determined that the cooking time determined in step S16 has elapsed, the upper and lower heaters 14, 15, 16
The power is cut off and this cooking is finished.

According to the present embodiment as described above, the second humidity detecting element 33 is located at a portion having a temperature higher than that of the first humidity detecting element 31, for example, on the heating cooking chamber 4 side, The sensor output Vout has a characteristic of increasing in non-frozen bread and a characteristic of decreasing in frozen bread. In other words, the change characteristics of the frozen bread and the non-frozen bread show opposite characteristics, and as a result, it is possible to quickly determine whether the bread is frozen or unfrozen immediately after the start of heating, and further, both characteristics are opposite characteristics. That is, since the two characteristics are clearly different, the reliability of the determination is also high. In this case, the air in the cooking chamber 4 is not forcibly blown against the humidity sensor 24 by the fan, so that the food is not dried.

Further, in this embodiment, "microwave cooking"
Is designated and heating is performed, the magnetron 6 is driven and the blower fan device 8 is also driven. In this "microwave cooking" as well, the food is frozen or not frozen. I am trying to determine if it is frozen. In the case of this "microwave cooking", when the food is heated, the amount of steam generated from the food is large at the beginning of heating due to the heating method, and the steam is blown, but the cooking chamber 4 tends to accumulate in the upper part (ceiling part) of the nozzle 4 and is exhausted through the duct 20 by blowing air, but the amount of water vapor in the upper part of the duct 20 also increases.

Here, in this embodiment, since the open type second humidity detecting element 33 is arranged in the lower part of the duct 20, the humidity sensor 24 has a detection output characteristic as shown in FIG.
The characteristics shown in No. 1 can be satisfactorily obtained.
That is, if the open second humidity detecting element 33 is provided in the upper portion of the duct 20, the humidity is excessively attached to the second humidity detecting element 33 and the heat radiation amount is too large, and the detection output is Even frozen foods and non-frozen foods will show similar output characteristics. In the present embodiment, however, such an inconvenience can be eliminated by disposing the open second humidity detecting element 33 in the lower portion of the duct 20.

Further, in this embodiment, the humidity sensor 2
Since the cable 36 is led out from a portion of the sensor case 25 that is an outer case of 4 that is far from the cooking chamber 4, the wiring work of the cable 36 is facilitated, and
The cable 36 can be protected from heat. Further, according to the present embodiment, since the duct 20 is made of metal and the humidity sensor 24 is directly fixed to the duct 20, heat transfer to the humidity sensor 24 is improved and the detection accuracy of the humidity sensor 24 is improved. Can contribute.

Furthermore, according to this embodiment, the insertion piece 3 is attached to one edge of the sensor case 25 of the humidity sensor 24.
4 is formed, a screw mounting piece portion 35 is formed on the other edge portion, the insertion piece portion 34 is inserted and engaged with a portion of the duct 20 on the heating cooking chamber 4 side, and the outside of the duct 20 is formed. By fixing the screw mounting piece 35 to the part,
Since it is fixed to the duct 20, there are few screwing steps,
The humidity sensor 24 can be easily attached, as compared with the case where all the plurality of places of the humidity sensor 24 are screwed.
Since the screwing position is on the outside of the duct 20, it is easy to perform the screwing work.
The mountability of is improved. Moreover, since the humidity sensor 24 is attached to the duct 20 in a surface contact state, heat transfer to the humidity sensor 24 is further improved, which can further contribute to improvement in detection accuracy.

Next, FIG. 13 shows a second embodiment of the present invention, in which the structure of the humidity sensor 51 is different from that of the first embodiment. That is, the first humidity detecting element 52 of the closed type and the second humidity detecting element 53 of the open type are arranged side by side in the direction in which the insertion piece portion 34 and the screw attachment piece portion 35 are arranged. As a result, in the duct 20, the second humidity detecting element 52 is arranged so as to be located above the first humidity detecting element 51.

According to this embodiment, since the second humidity detecting element 52 is located above the first humidity detecting element 51, the second humidity detecting element 53 has the first humidity detecting element 53. The temperature becomes higher than that of the humidity detecting element 52. Therefore, the sensor output V becomes equal to that in the "toast cooking" as in the above-described embodiment.
Out has a characteristic of increasing in non-frozen bread, and has a characteristic of decreasing in frozen bread. As a result, the same effect as in the first embodiment can be obtained.

FIG. 14 shows a third embodiment of the present invention. This embodiment differs from the first embodiment in the following points. That is, a predetermined time, for example 120
After a second, the output Vout of the humidity sensor 24 is detected (step G6), and the change amount Δd of this output Vout is calculated in step G6.
7, and whether or not this change amount Δd is “−0.1 or more” (step G8) or “whether −0.3 or more and less than −0.1” (step G9). to decide. If the amount of change Δd is “−0.1 or more”, it is determined to be room temperature bread (step G10), and “when less than −0.1, −
If it is "0.3 or more", it is determined to be intermediate bread (step G11), and if it is "less than -0.3", it is determined to be frozen bread (step G12).

In the third embodiment, the judgment control can be simplified by judging the state of the loaf of bread based on the output Vout after the lapse of a predetermined time from the start of heating. Moreover, in this case as well, the output Vout of the humidity sensor 24 exhibits the characteristic of increasing in the non-frozen bread and the characteristic of decreasing in the frozen bread, so that the above-mentioned predetermined time is set to "120 seconds" as in the present embodiment. Even if it is set to a short time, the bread condition can be sufficiently judged.

In each of the above embodiments, the humidity sensor 24
The output Vout of the above is illustrated for the case where the frozen food drops and the non-frozen food rises.
This output Vout rises in frozen foods by switching the connection relationship between the humidity detecting elements 31 and 33 of FIG. 1 or by reversing the input relationship of the intermediate connection points P1 and P2 to the amplifier 41, and non-freezing. You may make it obtain the characteristic that descends with food.

[0035]

As apparent from the above description, the present invention has the following effects. According to the first aspect of the invention, in the duct, the open second humidity detecting element of the humidity sensor is located at a position where the temperature becomes higher than that of the closed first humidity detecting element. Thus, it is possible to quickly determine whether the food is frozen or non-frozen without drying the food, and further it is possible to increase the reliability of the determination.

According to the invention of claim 2, in the duct, the open second humidity detecting element of the humidity sensor is
Since it is located closer to the heating and cooking chamber than the closed type first humidity detecting element, it is possible to quickly determine whether the food is frozen or not, without drying the food.
The reliability of the determination can be increased.

According to the invention of claim 3, in the duct, the open second humidity detecting element of the humidity sensor is
By arranging it above the first sealed humidity detecting element, it is possible to quickly determine whether the food is frozen or non-frozen without drying the food, and further increase the reliability of the determination. be able to.

According to the fourth aspect of the present invention, whether the food is frozen or non-frozen can be satisfactorily determined even when the heating means is a magnetron.

According to the fifth aspect of the present invention, the judgment control of the food condition is simplified. According to the invention of claim 6, the wiring work of the cable is facilitated and the cable can be protected from heat. According to the invention of claim 7, heat transferability to the humidity sensor is improved, which can contribute to improvement of detection accuracy. According to the invention of claim 8, the attachment of the humidity sensor can be improved, and the heat transfer to the humidity sensor is further improved, which can further contribute to the improvement of the detection accuracy.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional side view of a main part showing a first embodiment of the present invention.

[Fig. 2] Front view of the entire fracture

FIG. 3 is a cross-sectional plan view

FIG. 4 is a perspective view of the humidity sensor as viewed from the rear side.

FIG. 5 is a perspective view of the humidity sensor as seen from the front side.

FIG. 6 is a perspective view of a duct.

FIG. 7 is a sectional view of the humidity sensor.

FIG. 8 is a different sectional view of the humidity sensor.

FIG. 9 is a block diagram of an electrical configuration.

FIG. 10 is a circuit diagram of a humidity detection circuit.

FIG. 11 is a diagram showing characteristics of sensor output.

FIG. 12 is a flowchart showing control contents.

FIG. 13 is a view corresponding to FIG. 1, showing a second embodiment of the present invention.

FIG. 14 is a view corresponding to FIG. 12 showing a third embodiment of the present invention.

FIG. 15 is a sensor output characteristic diagram showing a conventional example.

[Explanation of symbols]

Reference numeral 1 is a range main body, 4 is a cooking chamber, 6 is a magnetron (heating means), 8 is a blower fan device, 14 and 15 are upper heaters (heating means), 16 are lower heaters (heating means), 20
Is a duct, 24 is a humidity sensor, 25 is a sensor case (outer case), 28 is a reference sensor part, 29 is a detection sensor part, 30 is a sealed case part, 31 is a first humidity detection element,
Reference numeral 32 is an open case portion, 33 is a first humidity detecting element, 34 is an insertion variation portion, 35 is a screw attachment piece portion, 36 is a cable,
37 is a humidity detecting circuit, 41 is an amplifier, 51 is a humidity sensor, 52 is a first humidity detecting element, and 53 is a second humidity detecting element.

Claims (8)

[Claims] 1. A heating and cooking chamber in which food is placed, a heating means for heating the food, a duct leading from the heating and cooking chamber to the outside, a closed first humidity detecting element, and an open first And a humidity sensor arranged in the duct such that the second humidity detecting element is located at a position where the temperature of the second humidity detecting element is higher than that of the first humidity detecting element. And a determination unit that determines whether the food is frozen or non-frozen based on the detection output from the humidity sensor when heated by the heating unit. 2. A heating and cooking chamber in which food is placed, a heating means for heating the food, a duct leading from the heating and cooking chamber to the outside, a closed first humidity detecting element, and an open first And a humidity which is arranged so that the second humidity detecting element is located closer to the cooking chamber than the first humidity detecting element in the duct. A heating cooker comprising: a sensor; and a determination unit that determines whether food is frozen or non-frozen based on a detection output from the humidity sensor when heated by the heating unit. 3. A heating and cooking chamber in which food is placed, a heating means for heating the food, a duct leading from the heating and cooking chamber to the outside, a first humidity detecting element of closed type and an open type first humidity detecting element. And a humidity sensor arranged such that the second humidity detecting element is located above the first humidity detecting element in the duct. A heating cooker comprising: a determination unit that determines whether food is frozen or non-frozen based on a detection output from the humidity sensor when heated by the heating unit. 4. A blower fan device is provided for putting external air into a cooking chamber and discharging it from a duct,
A magnetron is provided as a heating means, the blower fan device is operated during heating by the magnetron, and the second humidity detecting element is arranged so as to be located below the first humidity detecting element. The cooking device according to claim 1 or 2, characterized in that 5. The determination means is adapted to determine whether to freeze or not-freeze based on a value of a detection output from a humidity sensor after a predetermined time has elapsed from the start of heating. The heating cooker according to any one of 3 above. 6. The heating cooker according to claim 1, wherein the humidity sensor has a cable extending from a portion of the outer case remote from the heating chamber. 7. The heating cooker according to claim 1, wherein the duct is made of metal, and the humidity sensor is directly fixed to the duct. 8. The humidity sensor has a plug-in piece on one edge of the outer case and a screw-mounting piece on the other edge, and the plug is inserted into a portion of the duct on the side of the cooking chamber. By inserting and engaging one of the parts and screwing the screw mounting piece to the outer side portion of the duct,
The heating cooker according to claim 7, wherein the heating cooker is fixed to the duct in a surface contact state.