JPS63269492A - Cooker - Google Patents

Abstract

PURPOSE:To decrease a consumed power and miniaturize a power source transformer without occurrence of abnormal heating after release of a power failure by providing a non-self-hold type relay controlling opening/closing of a main circuit and self-hold type relays controlling turning on electricity to variable equipments in a load side after the former relay. CONSTITUTION:A main relay 31, power control relay 32, mode switch relay 33, motor drive relay 34, and operation part 40 are connected to a control part 30. The relay 31 is a non-self-hold relay controlling opening/closing of a main circuit and other relays 32-34 are self-hold type relays controlling turning on electricity for variable equipments in a load side after the relay 31. Consequently when an electric failure is released, the relay 31 remains de- energized, the off state of a contact 31a continues, and the main circuit becomes an opened state. This enables abnormal heating such as unnecessary continuation of an oscillation motion of a magnetron 7 or a motion of a heater 8 to be prevented.

Description

[Detailed description of the invention] [Purpose of the invention] <Industrial application field> The present invention relates to a cooking appliance such as a microwave oven.

(Prior Art) In cooking appliances such as microwave ovens, relays are used to control the opening and closing of the main circuit and to control the supply of electricity to various devices.

However, since relays maintain the state by passing current through coils, they consume a lot of power, making it difficult to increase the size of the power transformer. l? There is a problem.

Therefore, it is conceivable to use a so-called self-holding type relay that requires current only when changing the state and maintains the state even if no current flows after the state has changed. In other words,
This makes it possible to reduce power consumption and downsize the source/transformer.

(Problems to be Solved by the Invention) However, when such a self-holding relay is used, the following problems occur.

That is, if a power outage occurs during cooking, the oscillation operation of the magnetron is stopped and the control unit is reset. Then, when the power outage is lifted, the control unit remains reset, but the magnetron starts oscillating again, which can continue indefinitely, creating a very dangerous situation.

This invention was made in view of the above circumstances,
The purpose of this is to reduce power consumption without causing abnormal heating after the power outage is lifted, and 1! An object of the present invention is to provide a cooking device that enables miniaturization of a source transformer.

[Structure of the Invention] (Means for Solving the Problems) A non-self-holding relay that controls opening and closing of the main circuit, and a self-holding type that controls energization to various devices on the load side of the relay's contacts. A relay is provided.

(Function) By using a self-holding relay, the distance is 9 m! force is reduced. Further, by reducing power consumption, the power transformer can be downsized. Further, when a power outage occurs, the self-holding relay is deenergized, and the contacts of the relay remain in the off state even after the power outage is canceled, and the main circuit becomes open.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 2, reference numeral 1 denotes a heating chamber, and a door (not shown) is pivotally supported at the front opening of the heating chamber 1 so as to be openable and closable. A rotating plate 2 for placing food is rotatably provided at the bottom of the heating v1, and a rotating plate drive motor 4 is connected to the center of the back surface of the rotating plate 2 via a shaft 3 penetrating the bottom wall of the heating chamber 1.
is connected to.

Furthermore, a high-frequency radio wave irradiation port 5 is formed on the ceiling surface of the heating chamber 1, and one end of a waveguide 6 is communicated with the irradiation port 5. A magnetron 1 is provided on the outer periphery of the other end of the waveguide 6, and an antenna 1a of the magnetron 7 is introduced into the waveguide 6.

Further, an electric heater 8 is disposed in the upper part of the heating chamber 1 . A light irradiation port 9 is formed in the upper part of the side wall of the heating chamber 1,
Outside the light irradiation port 9, a so-called interior light 10 for illuminating the heating room is provided.

FIG. 1 shows the control circuit.

20 is a commercial AC power supply, and the power supply 20 and use 21,
Door switches 22a, 22b, relay contact 31a
, the primary coil 23a of the high voltage transformer 23 is connected in series with the normally closed side of the relay contact 32a and relay contact 33a.

The anode and cathode of the magnetron 7 are connected to the secondary coil 23b of the high voltage transformer 23 via a half-wave voltage doubler rectifier circuit consisting of a high voltage capacitor 24 and a high voltage diode 25. The heater (cathode) of the magnetron 1 is connected to the secondary coil 23c of the high voltage transformer 23.
and the anode is grounded.

Furthermore, for M'1120, fuse 21, door switches 22a, 22b, relay contact 31a, jjL
The heater 8 is connected in series through the normally open side of the /- contact 32a1 relay contact 33a.

In addition, for the power supply 20, a fuse 21, a door switch 2
The interior light 10 is connected through the 1 relay contact 31a in series. And interior light 10
The rotary plate drive motor 4 and the magnetron cooling fan motor 26 are respectively connected through relay contacts 34a.

Note that a door monitor switch 22c is connected to the Ii source 20 via a fuse 21 and door switches 22a and 22b in series.

On the other hand, a fuse 21 and a power transformer 27 are connected to the power supply 20.
A control unit 30 is connected via the. This control section 30
The microcomputer controls the entire microwave oven and consists of a microcomputer and its peripheral circuits.

A main relay 31 , a power control relay 32 , a mode switching relay 33 , a motor drive relay 34 , and an operation section 40 are connected to the control section 30 . Here, the main relay 31 is a non-self-holding type relay, and controls opening and closing of the main circuit. The other relays 32, 33, and 34 are self-holding type relays, and control energization to each Pj device on the load side of the main relay 31.

Next, the operation in the above configuration will be explained.

Food is placed on the rotating plate 2 in the heating v1, and the door is closed. Then, use the operation unit 40 to set the microwave cooking mode.

Set the heating output and cooking time, and perform the cooking start operation.

Then, the control unit 30 supplies current to the relay 31 to energize the relay 31, turning on the contact 31a and closing the main circuit. Further, current is applied to the relay 34 to turn on the contact 34a to form an energizing path for the rotary plate drive motor 4 and the magnetron cooling fan motor 26. Then, current is intermittently passed through the relay 32, and the contact 32a is turned on and off at a duty corresponding to the set heating output.

In this case, the non-self-holding type relay 31 is energized continuously, but the self-holding type relay 34 is energized only temporarily when the state changes for the first time. Further, the relay 32 is energized only when the state changes when the contact 32a is turned on or turned off.

In this way, the main circuit is closed and the relay contact 32a is turned on and off, so that the magnetron 7 oscillates at the set heating output, and high-frequency radio waves are supplied into the heating chamber 1. In other words, dielectric heating cooking begins. Further, the rotating plate drive motor 4 operates to rotate the rotating plate 2, and the magnetron cooling fan motor 26 operates to supply cooling air to the magnetron 1.

During cooking, the control unit 30 measures the elapsed cooking time, and when the elapsed time reaches the set cooking time, it stops energizing the relay 31, de-energizes the relay 31, and turns off the contact 31a to turn off the main cooking time. Open the circuit. In other words, the dielectric heating cooking ends. Furthermore, a contact point 32a.

The relays 32 and 34 are energized as appropriate so that the relay 34a is turned off.

In addition, in the oven cooking mode by heat generation of the heater 8, the contact 33a of the relay 33 is switched to the normally open side, and the heater 8 is energized.

In this way, by using self-holding relays 32, 33, and 34 that require current only when the state changes, power consumption can be reduced and it is economical. This reduction in power consumption allows the power transformer 27 to be downsized. This miniaturization greatly contributes to making the microwave oven smaller and lighter in size as a whole.

Incidentally, a power outage may occur during cooking, and in that case, the oscillation operation of the magnetron 7 is stopped and the control unit 30 is reset. In this case, the non-self-holding type relay 31 is deenergized and the contact 31a is turned off, but the on state of the contact 34a of the self-holding type relay 34 and the on or off state of the contact 32a of the self-holding type relay 32 is remains as is.

Thereafter, when the power outage is canceled, the relay 31 remains de-energized, the contact 31a continues to be in the off state, and the main circuit is in the open state. Therefore, even if the contact 32a is on, the magnetron 7 will not operate in oscillation. Furthermore, the rotating plate drive motor 4 and the magnetron cooling fan motor 26 do not operate. Furthermore, the heater 8 does not operate in the open cooking mode.

Therefore, abnormal heating such as unnecessary continuation of the oscillation operation of the magnetron 7 and operation of the heater 8 can be prevented.
It's safe. Accordingly, reliability can be significantly improved.

Although the above embodiment has been described using an example in which there are three self-holding relays, the number can be set as appropriate depending on the circuit situation. Regarding the number of non-self-holding type relays, at least one relay may be provided for opening and closing the main circuit.

In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without changing the gist.

[Effects of the Invention] As described above, according to the present invention, there is a non-self-holding type relay that controls the opening and closing of the main circuit, and a self-holding type relay that controls the energization of various devices on the load side from the contacts of this relay. Since this type of relay is provided, it is possible to provide a cooking appliance that can reduce power consumption and downsize the power transformer without causing abnormal heating after the power outage is canceled.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a control circuit in one embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a heating chamber and its surroundings in the same embodiment. 31... Main relay (non-self-holding relay), 3
2... Power control relay (self-holding type relay), 33... Mode switching relay (self-holding type relay), 34... Motor drive relay (self-holding type relay). Applicant's agent Patent attorney Takehiko Suzue Figure 2

Claims (1)

[Claims] A cooking appliance characterized by comprising a non-self-holding type relay that controls opening and closing of a main circuit, and a self-holding type relay that controls energization to various devices on the load side of the relay's contacts.