JPH03168533A - Microwave oven - Google Patents

Abstract

PURPOSE:To effectively control a microwave generator even if quantity of gas from an article to be cooked is small by providing air flow rate regulating means for regulating air flow rate into a heating cooking chamber of a blower into the chamber in response to weight information of the article. CONSTITUTION:If weight of an article to be cooked is small, air flow rate into a heating cooking chamber 2 can be regulated, for example, reduced in response to weight information of the article, and even if the quantity of gas to be generated from the article is small, the concentration of the gas during exhausting through an exhaust passage 20 becomes high. Accordingly, a microwave generator 7 is effectively controlled based on a detection signal output from a gas sensor 23. If the weight of the article is heavy, the air flow rate to the chamber 2 is regulated, for example, increased in response to the weight information of the article to provide the same degree as prior structure, and the generator 7 can be controlled based on the detection signal output from the sensor 23 in the same manner as the prior art.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a microwave oven equipped with a microwave generator for heating food stored in a heating cooking chamber.

(Prior Art) This type of microwave oven has conventionally been equipped with a blower device that blows outside air into the cooking chamber, and has also been equipped with a blower device that blows outside air into the cooking chamber. A gas sensor for detection is provided, and the microwave generator is controlled based on a detection signal output from the gas sensor. In this case, at the end of cooking, a large amount of gas (containing moisture) is generated from the food being cooked, and the concentration of gas in the exhaust gas passing through the exhaust path increases. Heating is automatically terminated when the signal reaches, for example, a predetermined level. In this configuration, a cooling fan for cooling the magnetron is used as an air blower, and a certain amount of outside air, which is cooled air after cooling the magnetron, is sent into the cooking chamber by this cooling fan.

(Problems to be Solved by the Invention) In the conventional structure described above, when the weight of the food to be cooked is large and the amount of gas generated from it is large, the gas in the exhaust gas passing through the exhaust path at the end of cooking is As the concentration increases and the detection signal from the gas sensor reaches a predetermined level, heating can be automatically terminated.

However, when the weight of the food to be cooked is small and the amount of gas generated from it is small, a certain amount of outside air is sent into the heating cooking chamber by the blower, so when the cooking is finished, the exhaust gas that passes through the exhaust path is The concentration of gas may not be high. For this reason, there was a possibility that the detection signal from the gas sensor would not reach a predetermined level, making it impossible to complete the heating.

Therefore, an object of the present invention is to provide an electronic device that can reliably control a microwave generator based on a detection signal output from a gas sensor even when the weight of the food to be cooked is small and the amount of gas generated from the food is small. There is a microwave available.

[Structure of the Invention] (Means for Solving the Problems) The microwave oven of the present invention includes a microwave generator that heats food stored in a cooking chamber, and also blows outside air into the cooking chamber. The gas sensor is provided in an exhaust path for discharging the air inside the cooking chamber to the outside and detects gas generated from the food to be cooked. In the microwave generator, a weight information generating means is provided for generating weight information of the food to be cooked, and the amount of air blown into the heating cooking chamber by the air blower is calculated from the weight information of the food to be cooked. It is characterized by the provision of a means for adjusting the amount of air blown according to the amount of air blown.

(Function) According to the above means, when the weight of the food to be cooked is small, the amount of air blown into the heating cooking chamber can be adjusted, for example, reduced, according to the information on the weight of the food to be cooked. Even if the amount of gas generated is small, the concentration of gas in the exhaust gas passing through the exhaust path is high, so the microwave generator can be reliably controlled based on the detection signal output from the gas sensor.

In addition, when the weight of the food is large, the amount of air blown into the heating cooking chamber can be adjusted, for example, increased to the same level as the conventional configuration, depending on the information on the weight of the food, so it is possible to Therefore, the microwave generator can be controlled based on the detection signal output from the gas sensor.

(Example) An example of the present invention will be described below with reference to the drawings.

First, in FIGS. 1 and 2, a heating cooking chamber 2 is provided in an outer box 1, and a door 3 is provided to open and close a front opening of this heating cooking chamber 2. An operation panel 4 is provided at the right end of the front surface of the outer box 1, and various operation switches (not shown) are provided on this operation panel 4. At the bottom of the heating cooking chamber 2, as shown in FIG. 2, a rotary plate 5 is provided which is rotationally driven by a gourd motor (not shown). The rotary plate 5 and the motor for driving it are placed on a weight information generating means, such as a weight sensor 6. This heavy melon sensor 6 is of a type that detects, for example, a change in capacitance between electrodes, and is designed to detect the total weight including the rotating plate 5 and the motor, etc., so that it is placed on the rotating plate 5. The weight of the cooked food (not shown) is detected and a weight information signal is output.

Further, a magnetron 7 constituting a microwave generator is provided on the right side of the heating cooking chamber 2, and the microwave output from the magnetron 7 causes the microwaves contained in the heating cooking chamber 2 to be placed on the rotary plate 5. The food placed on it is heated using microwaves. Behind the magnetron 7, a blower device 10 composed of a fan 8 and a fan motor 9 is arranged. This blower device 10
The system takes in outside air through an intake port 12 formed in the back plate 11, cools electrical components such as the magnetron 7 with the outside air, and also directs the outside air through a discharge port 13 formed in the right side wall of the cooking chamber 2. Air is blown into the heating cooking chamber 2. A damper 14 is provided at the discharge port 13 to adjust the amount of outside air blown into the heating cooking chamber 2 . As shown in FIG. 3, this damper 14 is attached to a shaft 16 of a stepping motor 15, and is configured to rotate together with the shaft 16 about the Ill 16 as a fulcrum. The rotation angle of the stepping motor 15 allows the opening angle, which is the rotation angle of the damper 14, to be adjusted.

In this case, the damper 14 rotates from an opening angle of 0 degrees (the closed state shown by the solid line in FIG. 1) to 30 degrees (the fully open state shown by the two-dot chain line in FIG. 1). A cam 17 is attached to the other end of the shaft 16, and when the opening angle of the damper 14 is 0 degrees, the protrusion 1. 7a, the initial position detection switch 18 is turned on. As a result, the position at which the damper 14 has a rotation angle of 0 degrees is detected by the first friend position detection switch 18. Note that in FIG. 1, one is an air guide.

On the other hand, an exhaust passage 20 is provided on the left side of the heating cooking chamber 2, and the air in the heating cooking chamber 2 is vented through a vent 21 formed on the left side wall of the heating cooking chamber 2, and through the exhaust passage 20 and the back plate. 1
It is designed to be exhausted to the outside through an exhaust port 22 formed in 1. Inside the exhaust path 20, a gas sensor 2 is provided which detects gas such as steam generated from the food on the rotary plate 5.
3 is provided.

The detection signal output from the gas sensor 23 is given to a control circuit, for example, a microcomputer 24, as shown in FIG. This microcomputer 24
is provided with a weight information signal from the weight sensor 6 and a detection signal from the initial position detection switch 18.

The microcomputer 24 also drives the stepping motor 15 via a drive circuit (not shown). In this case, the stepping motor 15 is
The damper 14 is set to rotate 2.5 degrees when receiving a 1-step pulse. The microcomputer 24, the damper 14, the stepping motor 15, etc. constitute an air flow rate adjusting means 25.

Next, the operation of the above configuration will be explained with reference to FIG. 4 as well. FIG. 4 is a flowchart showing an outline of the operation control program stored in the microcomputer 24. As shown in FIG.

When operation is started with food placed on the rotary plate 5, the weight of the food is first detected by the weight sensor 6 (step S1), and the weight information signal of the food is sent to the microcomputer 24. given to. Next, when the weight is less than 100g, the microcomputer 24 gives a 4-step pulse to the stepping motor 15 to set the opening angle of the damper 14 to 10 degrees, so that 100g<weight≦3
When the weight is 00g, 6 step pulses are given to the stepping motor 15 to set the opening angle of the damper 14 to 15 degrees, and when 300g<weight≦500g, 8 step pulses are given to the stepping motor 15 to set the opening angle of the damper 14. If the weight exceeds 500 g, 12 step pulses are applied to the stepping motor 15 to set the opening angle of the damper 14 to 30 degrees (steps 82 to 8). Then, the fan motor 9 is energized, and the fan 8 blows outside air into the heating cooking chamber 2 (step S
9). When the rotational speed of the fan 8 becomes stable, the detected value of the gas sensor 6 before the start of cooking is read and set as the initial value Do (step S10). In this case, since the opening angle of the damper 14 is set as described above, the amount of outside air blown is adjusted according to the weight of the food to be cooked. Next, the magnetron 7 is activated to start heating the food using microwave output (step S11). Thereafter, the gas generated from the food as cooking progresses is detected by the gas sensor 6, and the detected value is set as DI, and the temperature is increased until the difference between this D1 and the upper Hc2 DO reaches a preset value DA. Continue heating (Step S
1 2, 1 3). Then, when DA≦DI−D◯, the oscillation of the magnetron 7 is stopped to stop heating, and the fan motor 9 is cut off to stop the fan 8 (step S14). At this time, when the gas sensor 6 detects gas generated from the food as cooking progresses, the amount of outside air blown is adjusted according to the weight of the food. When the weight is small, the amount of air blown into the heating cooking chamber 2 is reduced, so even if the amount of gas generated from the cooking food is small, unlike conventional methods, the amount of gas in the exhaust gas passing through the exhaust path is reduced. Concentration increases. Therefore, at the end of cooking, the difference between the detected value D1 output from the gas sensor 6 and the initial value Do reaches the predetermined value DA without fail, and the magnetron 7 can be stopped. On the other hand, when the weight of the food to be cooked is large, the amount of air blown into the cooking chamber can be increased to the same level as in the conventional configuration.
When the difference between the detected value D1 outputted from the gas sensor 6 and the initial value DO reaches a predetermined value DA, the driving of the magnetron 7 can be stopped.

Thereafter, the stepping motor 15 is reversed to return the opening angle of the damper 14 to 0 degrees (step S15). In this case, the number of step pulses given to the stepping motor 15 when opening the damper 14 at the start of operation is stored, and the angle of reversal is set based on this.

Note that if the stored value of the step pulse is lost due to a power outage, etc., the initial position detection switch 1 shown in FIG.
By rotating the stepping motor 15 in the reverse direction until 8 is turned on, the opening angle of the damper 14 can be set to 0 degrees.

Further, in the above embodiment, when adjusting the amount of outside air blown into the heating cooking chamber 2, the opening angle of the damper 14 is adjusted while keeping the amount of air blown by the fan 8 constant. The amount of cooling air used to cool electrical components such as the following is constant. Therefore, the cooling efficiency for cooling electrical components such as the magnetron 7 is the same as before, so even if the amount of outside air blown into the heating cooking chamber 2 is adjusted according to the weight of the food, the magnetron 7 etc. There is no adverse effect on the cooling of electrical parts.

In the above embodiment, the weight sensor 6 is provided as a weight information generating means, and the weight detection result thereof is handled as weight information, but the invention is not limited to this. For example, an fffffi input switch may be provided, This switch manual force may be treated as weight information.

[Effects of the Invention] As is clear from the above description, the present invention is configured to adjust the amount of air blown into the heating cooking chamber by the air blower according to the information on the weight of the food to be cooked. Even when Et is small and the amount of gas generated from the food to be cooked is small, the excellent effect is that the microwave generator can be reliably controlled based on the detection signal output from the gas sensor.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional view, FIG. 2 is a vertical sectional front view showing an electrical configuration, and FIG.
The figure is a perspective view of a portion of the damper, and FIG. 4 is a flow chart. In the drawing, 2 is a heating cooking chamber, 6 is a weight sensor (weight information generating means), 7 is a magnetron (microwave generator),
Reference numeral 10 indicates an air blower, and reference numeral 25 indicates an air blowing amount adjusting means.

Claims (1)

[Claims] 1. A microwave generator that heats the food stored in the cooking chamber, a blower that blows outside air into the cooking chamber, and an exhaust path that discharges the air inside the cooking chamber to the outside. a gas sensor that detects gas generated from the food to be cooked, and the microwave generator is controlled based on a detection signal output from the gas sensor, the weight for generating weight information of the food to be cooked; A microwave oven comprising: an information generating means; and an air blowing amount adjusting means for adjusting the air blowing amount of the air blower into the heating cooking chamber according to information on the weight of the food to be cooked.