JPH03238786A - Microwave oven - Google Patents

Abstract

PURPOSE:To prevent a failure in cooking, etc., by stopping operation of an oven function, and performing informing operation when a determining means determines that a detected speed is lower than a target speed. CONSTITUTION:While a microwave oven function is being operated, a rotation speed detector 37 detects a rotation speed of a motor 6, and a determining means of a control circuit 30 determines whether the detected speed is lower than a target speed. When the detected speed is judged to be lower than the target speed M, a failure coping means of the control circuit 30 stops operation of the oven function as well as performs informing operation. That is, if the rotation speed of the motor 6 has dropped or the rotation has stopped due to a deviation of a position where food is mounted with respect to a rotating dish or due to occurrence of a defect of a bearing on the motor 6 and a turning force transmission path, this can be automatically detected and the oven operation can be stopped. Thus a failure in cooking can be eliminated.

Description

Detailed Description of the Invention [Objective of the Invention J (Field of Industrial Application) The present invention provides a microwave oven function that heats food using microwaves while rotating a rotary plate on which food is placed, and a kneading member for kneading bread dough. This invention relates to a microwave oven equipped with a kneading function by rotating.

(Prior Art) Conventionally, in a microwave oven, food is heated by irradiating the food with microwaves output from a magnetron while rotating a rotating plate on which the food is placed.

In recent years, microwave ovens have been provided with a bread-making function in addition to the above-mentioned normal oven function, and the bread-making function includes a kneading function of kneading bread dough using a kneading member. Some microwave ovens of this type are configured to have separate drive motors for driving the rotary plate and the kneading member, respectively. However, since this type has two motors, there is a problem that the cost is high.

To solve this problem, there is a structure in which the rotary plate and the kneading member are selectively driven by one motor. In this device, when heating food using microwaves, it is more convenient to cook the food by rotating the rotating plate relatively slowly and irradiating the food with microwaves evenly, so the motor is set relatively slowly. I'm trying to rotate it.

In addition, in the case of kneading bread dough, bread dough can be produced better if the kneading member is rotated at a certain speed, so the motor is rotated faster than when the rotating plate is driven. Specifically, in the case of the kneading function, the motor is energized continuously so that the rotation speed of the motor is relatively fast, and in the case of the range function, the motor is energized in a preset short-cycle energization/disconnection pattern. By turning off the power to the motor, the rotational speed of the motor is slowed down.

(Problem to be Solved by the Invention) By the way, in the range function described above, the output torque is lowered by intermittent energization of the motor rather than the rated output when the motor is energized continuously, so it is sensitive to load fluctuations, and therefore the following There is a problem with this. In other words, the weight of the food is a variable factor in the load on the motor, and in this case, if the motor's energization pattern is set in advance to obtain the motor's rotational speed according to the weight, the motor's rotational speed can be adjusted appropriately. It is thought that the speed can be maintained at a certain speed. However, when the food is placed not in the center of the rotating plate but near the edges, in addition to the weight of the food, unforeseen load factors such as unbalanced loads act on the rotating plate, resulting in an increase in the load on the motor. , the rotational speed of the motor decreases or stops. If operation is continued in such a state, cooking failures such as uneven heating of food will occur. Note that the above-mentioned unexpected load element is not limited to the above-mentioned food placement position, but includes, for example, deterioration over time of the motor and the bearing of the rotational force transmission path.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to detect a decrease in rotational speed or rotational stop of the motor during operation of the range function in a device that has a kneading function in addition to the range function and also uses a common motor for driving the rotary plate and the kneading member. To provide a microwave oven that can prevent cooking failures and the like.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a microwave function that heats food using microwaves while rotating a rotary plate on which food is placed, as well as a kneading function that kneads bread dough by rotating a kneading member. a rotation speed detector for detecting the rotation speed of the motor during operation of the range function; A determining means for determining whether the speed detected by the rotational speed detector has fallen below a preset target speed, and stopping the range function operation when the determining means determines that the detected speed has fallen below the target speed. It is characterized in that it is provided with an abnormality response means that also performs a notification operation.

(Function) When the microwave oven function is operating, the rotation speed detector detects the rotation speed of the motor. Then, the determining means determines whether or not this detected speed is lower than the target speed. The abnormality response means stops the range function operation and performs a notification operation when the determination means determines that the detected speed has fallen below the target speed. Therefore, if the rotational speed of the motor decreases or stops due to the food being placed on one side of the rotating plate or the bearing deteriorating, etc., the range function will be stopped. You can eliminate cooking mistakes.

Moreover, by performing the notification operation, the occurrence of an abnormality is notified, and measures to eliminate the cause of the abnormality can be promptly taken.

(Example) Hereinafter, a first example of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 3 shows the overall structure of the microwave oven, and FIG. 4 shows the structure of the main parts of the microwave oven. There is a door 2 inside the main body 1.
A heating chamber 3 is formed which is opened and closed by
A magnetron 4 is attached to the upper right side of the waveguide 5 via a waveguide 5. A cylindrical drive shaft 8 is arranged at the bottom of the heating chamber 3, and is rotatably driven by a motor 6, which is an induction motor, via a belt transmission mechanism 7. Transmission coupling 8a
is attached to the hollow part of the drive shaft 8.
A sensor shaft 9 that receives weight is inserted through the sensor shaft 9, and a weight sensor 10 that detects the weight applied to the sensor shaft 9 is provided at the lower end of the sensor shaft 9. Coupling 8 above
The rotating plate 11 and the kneading shaft 15 (see FIG. 5) are selectively engaged with the rotating plate 11 and the kneading shaft 15 (see FIG. 5). FIG. 4 shows a case where the coupling lla of the rotating plate 11 is removably engaged. A rotary plate 12 for placing food on this rotary plate 11 is arranged, and the weight sensor 10 detects the total weight of the rotary plate 11 and the rotary plate 12 as well as the food. Then, the weight of the rotating plate 12 is subtracted to detect the weight of only the food, and a detection signal of a level corresponding to the weight is output.

Furthermore, a bayonet engaging portion 13 is provided at the bottom of the heating chamber 3.
is firmly fixed thereto, and the bread container 14 is removably attached via the attachment portion 14a by the bayonet engagement portion 13 as shown in FIG. This bread container 1
A kneading shaft 15 is rotatably provided through the bottom of the kneading shaft 4, a kneading member 16 is attached to the upper end of the kneading shaft 15, and a cup that engages with the coupling 8a is attached to the lower end of the kneading shaft 15. A ring 17 is fixed.

FIG. 1 shows the electrical configuration. A door switch 19, a primary coil 20a1 of a high voltage transformer 20, a relay switch 21, and a door switch 2 are connected between one power terminal and the other power terminal of a power plug 18 connected to an AC power source.
2 are connected in this order, and a rectifying voltage doubler circuit 23 for driving the magnetron 4 is connected to the secondary coil 20b side of the high voltage transformer 20. moreover,
A well-known short switch 24, a series circuit between the motor 6 and the triac 25, a series circuit between the heater 26 and a relay switch 27, and an interior light 28 and a relay switch are connected between the load side terminals of the door switch 19 and 22. The series circuits with 29 are connected in parallel.

Further, the control circuit 30 includes a microcomputer 31, which not only controls the overall heating operation of the microwave oven but also functions as a determination means and an abnormality response means, as will become clear from the description below. This control circuit 30 is supplied with power by a step-down transformer 32 . Further, as shown in FIG. 3, this control circuit 30 is supplied with switch power from various switches 34 of an operating section 33 provided on the front surface of the main body 1, and also receives detection signals from the quantity sensor 10. is now given. The control circuit 30 also controls a display section 35 and a buzzer 36 provided in the control section 33. When "kneading" is set with the menu selection switch of the control section 33, the control circuit 30 controls the triac 25 to continuously energize the motor 6 as shown in FIG. , when the "range" is set, the motor 6 is controlled so that the rotational speed of the motor 6 does not fall below a preset target speed M under normal load conditions, regardless of which food 1ijll is being used. There is. That is, as shown in FIG. 7, for the motor 6,
Positive half-wave energization of AC power supply and a certain number of cycles Cn
The triac 25 is controlled so that the power interruption (10 to 15) and negative half-wave energization are repeated. In this case, the ROM of the microcomputer 31 stores the relationship between the level of the weight detection signal and the energization/disconnection pattern for the motor 6 as motor drive data. Data relating to a decrease in the number of power-off cycles Cn is stored. Therefore, the output torque of the motor 6 increases as the number of power-off cycles Cn shown in FIG. , it is configured to rotate at a speed that does not fall below a substantially constant target speed M unless there are unexpected load fluctuation factors.

Further, the rotational speed detector 37 shown in FIG. 1 is composed of, for example, a rotary encoder, which detects the rotational speed of the motor 6 and outputs a signal corresponding to the detected speed to the control circuit 30.

Now, the operation of the above configuration will be described. Now, when kneading bread dough using the kneading function, as shown in FIG.
When you set and turn on the start switch,
The control circuit 30 continuously energizes the motor 6 in the energization pattern shown in FIG. As a result, the kneading member 16 is driven to rotate at a relatively high rotational speed, and the bread dough material in the bread container 14 is kneaded.

On the other hand, when heating food using the microwave function, as shown in FIG. Set the "range" using the menu selection switch, set the cooking time using the time setting switch, and then turn on the start switch. Then, as shown in FIG. 2, the control circuit 30 controls the weight sensor 1.
Read the weight detection signal from 0 (step Sl),
Based on the level of the detection signal, the motor drive data is searched and a motor energization/disconnection pattern is set (step S2). Next, the control circuit 30 drives the motor 6 and the magnetron 4 (step S3). Then, after a certain period of time (the time when the motor 6 is considered to be in steady rotation), the detected speed by the rotational speed detector 37 is read (step S4), and it is determined whether or not this detected speed has fallen below the target speed M (step S5). ).

Here, if the food is placed evenly on the rotating plate 12 and there is no deterioration of the bearings, that is, if there are no unforeseen load fluctuation factors, the motor 6 will move at the target speed regardless of the weight of the food. It rotates faster than M. However, if there is no unexpected load variation element, it is determined in step S5 that the detected speed is equal to or higher than the target speed M, and it is determined in step S6 whether or not the set cooking time has elapsed.
), the drive of the magnetron 4 and the motor 6 is stopped (step S7), and the range function operation is stopped;
The cooking operation is then completed.

On the other hand, when there is the above-mentioned unexpected load variation factor, the load applied to the motor 6 is large, so the rotational speed of the motor 6 decreases and falls below the target speed M. In this case, the control circuit 30 determines in step S5 that the detected speed is lower than the target speed M, and stops driving the magnetron 4 and motor 6 (step S8), that is, stops the range function operation, and further The buzzer 36 is driven to output an alarm sound for notifying the abnormality, and the display 35 displays characters for notifying the abnormality (for example, characters such as "Please place the food in the center") (step S9).

According to this embodiment, when the microwave oven function is operating, the rotation speed detector 37 detects the rotation speed of the motor 6, and the determination means of the control circuit 30 determines whether or not this detected speed is lower than the target speed. Furthermore, when it is determined by the abnormality response means of the control circuit 30 that the detected speed has fallen below the target speed M, the range function operation is stopped and the notification operation is performed.
If the rotational speed of the motor 6 has decreased or stopped due to the food being placed on the rotary tray 12 being biased or the bearings in the motor 6 and the rotational force transmission path deteriorating, etc. This can be automatically detected and the microwave function operation can be stopped, thereby eliminating cooking failures.

Moreover, by performing the notification operation, the occurrence of an abnormality is notified, and measures to eliminate the cause of the abnormality can be promptly taken.

Note that the energization/disconnection pattern of the motor 6 in the range function is not based on the energization/disconnection pattern of the motor 6 shown in FIG. This may be done by phase control. In this case, as the level of the weight detection signal increases, the control angle α
You can set it to small.

The present invention is not limited to the above embodiments,
Various modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] As is clear from the above description, the present invention has a microwave function that heats food using microwaves while rotating a rotating plate on which food is placed, as well as a kneading function that kneads bread dough by rotating a kneading member. , wherein the rotary plate and the kneading member are selectively driven to rotate by one motor, a rotation speed detector for detecting the rotation speed of the motor when the range function is operated; A determination comparison means for determining whether the speed detected by the speed detector is lower than a preset target speed, and a range function operation is stopped when the determination means determines that the detected speed is lower than the target speed. and an abnormality response means for performing a notification operation.
With this, it is possible to prevent cooking failures by automatically detecting a decrease in motor rotation speed or rotation stop when the range function is operating, and also to prevent failures in cooking.Furthermore, since an alarm operation is performed, the occurrence of an abnormality will be notified and measures can be taken to eliminate the cause of the abnormality. It has excellent effects such as being able to take prompt action.

[Brief explanation of drawings]

1 to 7 show a first embodiment of the present invention, in which FIG. 1 is an electrical configuration diagram, FIG. 2 is a flowchart showing the control contents of the control circuit, and FIG. 3 is a perspective view of the whole. Figure, 4th
The figure is a vertical cross-sectional view of the main part showing how it is used in the range function, Figure 5 is a vertical cross-sectional view of the main part showing how it is used in the kneading function, and Figure 6 is a diagram showing the motor energization pattern during the kneading function. , 7th
The figure is a diagram showing a motor energization pattern during the range function. FIG. 8 is a diagram corresponding to FIG. 7 showing a second embodiment of the present invention. In the drawing, 3 is a heating chamber, 4 is a magnetron, 6 is a motor,
10 is a weight sensor, 11 is a rotating plate, 12 is a rotating plate, 14
16 is a bread container, 16 is a kneading member, 30 is a control circuit (comparison means, abnormality response means) 35 is a display device, 36 is a buzzer 37
indicates a rotation speed detector.

Claims (1)

[Claims] 1. In addition to a microwave function that heats food using microwaves while rotating a rotating plate on which food is placed, it also has a kneading function that kneads bread dough by rotating a kneading member, and a single motor operates the rotating plate and the kneading member. In the motor which is selectively driven to rotate, a rotation speed detector detects the rotation speed of the motor when the range function is activated, and a rotation speed detector detects the rotation speed of the motor when the rotation speed is lower than a preset target speed. The present invention is characterized by being provided with a determination means for determining whether or not the detected speed has fallen below the target speed, and an abnormality response means for stopping the range function operation and performing an alarm operation when the determination means determines that the detected speed has fallen below the target speed. Microwave oven.