JPH0445733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a microwave oven, and particularly relates to a microwave oven having a convection function.

(b) Conventional technology Figure 3 is an electrical circuit diagram of a conventional microwave oven of this type, where PG is a plug for connecting to a commercial power supply, FU is a fuse, TF is a temperature fuse, IS1 and IS2 are interlock switches, respectively. S1 is a monitor switch, FM is a fan motor, TM is a turntable motor, OL is an oven lamp, HE is a heater element, PT is a power transformer, C is a capacitor unit, RF is a rectifier, MT is a magnetron, and RU is a relay unit. , RY1 to RY6 are relays, CU is a control unit, TR is a thermistor, S2 is a cooking stop switch, S3 is a damper switch, DM is a damper motor, and CM is a convection motor.

When a signal is output from the control unit during convection cooking, relays RY2~
Voltage is applied to RY6, relay RY2 connects the turntable motor TM and oven lamp OL, relay RY3 connects the convection motor CM, and relay
RY4 operates heater element HE. Furthermore, relay RY4 is a thermistor for temperature control.
It is also controlled by TR. Relay RY5 drives a fan motor FM for cooling the outer shell and electrical parts of the microwave oven, and relay RY6 drives a damper motor DM for operating a damper.

Furthermore, in order to stop the damper at a predetermined position, a relay RY6 is controlled by a damper switch S3, which is opened and closed as the damper moves.

(C) Problems to be Solved by the Invention However, conventional microwave ovens require a control relay for each electrical component, making the control circuit complex and having a large number of parts, which is not economically preferable. .

The present invention has been made in consideration of these circumstances, and it is an object of the present invention to provide an economical microwave oven that uses fewer control relays.

(d) Means for Solving the Problems This invention has a convection function and uses a convection motor that drives a fan that circulates hot air inside the oven and a damper that blocks cold air from entering the oven. In a microwave oven equipped with a damper motor that opens and closes, there is provided a relay that selectively supplies power to a convection motor and a damper motor, a power supply path from the relay to the damper motor is cut off, and the damper motor is connected to the convection motor. A switch is provided that can be connected in parallel to the motor, and a cam is driven by a damper motor and switches the switch in conjunction with the opening/closing operation of the damper, and the relay starts driving the convection motor. The present invention provides a microwave oven characterized in that the damper motor is powered in parallel with the convection motor by the changeover switch and is driven until the damper is closed.

(E) Effect When the relay is turned on during convection cooking,
The convection motor is driven. At the same time, a damper motor connected in parallel to the convection motor via a switch is driven to close the damper. When the damper is in the closed state, a cam switches the switch and the damper motor stops.

At the end of the adjustment, the relay turns off and the convection motor stops. At the same time, the motor drive power source is connected to the damper motor via the relay and switch, so the damper motor is driven and the damper is opened. When the damper is opened, a cam switches the switch and the damper motor stops.

In this way, the control of the convection motor and damper motor, which was conventionally performed using two relays and one switch, is now performed using one relay and one switch.

(F) Embodiments The present invention will be described in detail below based on embodiments shown in the drawings. Note that this invention is not limited to this.

FIG. 1 is an electrical circuit diagram showing one embodiment of the present invention. In Figure 1, RY7 is normally open, normally closed,
A relay that has common contacts a, b, and c and connects the motor drive power source to the convection motor CM through the normally open and common contacts a and c. A damper motor DM having a contact point C is connected in parallel to a convection motor CM via first fixed and movable contacts A and C, and
The second fixed contact B is a switch connected to the normally closed contact B of the relay RY7, and the other circuits are the same as in FIG. 3.

Also, in Fig. 2 A, cam 1 is the damper motor DM.
The figure shows a state in which the movable contact c of the switch S4 is driven in the direction of the arrow by the cam 1 when the damper is opened, and the movable contact c of the switch S4 is closed to the first fixed contact A; A state in which contact B is closed is shown.

In this configuration, when the convection cooking signal is output from the control unit CU, voltage is applied to relays RY2, RY4, RY5, and RY7, and the turntable motor TM, oven lamp OL, convection motor CM, and heater element , HE and fan motor FM operate.

At this time, the damper is in the open state shown in FIG. 2A, so the damper motor DM is driven by voltage applied through the first fixed contact A and the movable contact C of the switch S4, and the damper is brought into the closed state. Operate it so that it works. When the damper is in the closed state, the switch S4 is switched by the cam 1 as shown in FIG. 2B, so the motor DM is stopped. When cooking is finished, common contact c of relay RY7 is connected to normally closed contact b, which supplies current to damper motor DM through second fixed contact B and movable contact C of switch S4, so that the damper Motor DM operates and drives the damper to the open state. As a result, the cam 1 and the switch S4 return to the state shown in FIG. 2A, and the damper motor DM stops.

In this way, the same operation as in the conventional example shown in FIG. 3 is performed.

(G) Effects of the Invention According to this invention, the convection motor and damper motor can be controlled by a common relay, which simplifies the control circuit and reduces the number of relays used, resulting in lower costs. becomes possible.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, FIGS. 2A and 2B are explanatory diagrams showing the configuration and operation of the main parts of the invention, and FIG.
FIG. 1...Cam, DM...damper motor, CM...
...Convection motor, RY7...Relay, S
4...Switch.

Claims (1)

[Claims] 1. A microwave oven that has a convection function and is equipped with a convection motor that drives a fan that circulates hot air inside the oven and a damper motor that opens and closes a damper that blocks cold air from entering the oven. , one relay selectively supplies power to the convection motor and the damper motor, and is provided to cut off a power supply path from the relay to the damper motor and connect the damper motor in parallel to the convection motor. It is equipped with one changeover switch and a cam that is driven by a damper motor and changes over the changeover switch in conjunction with the opening/closing operation of the damper, and when the relay starts driving the convection motor, the changeover switch causes the damper to be A microwave oven characterized in that a motor is powered in parallel with a convection motor and is driven until a damper is closed.