JP2000003781A - Microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave oven which is free of the adjustment for the latch switch fitting position and capable of preventing the contact changeover of the latch switch, even if a door is opened a little. SOLUTION: In a microwave oven, when a door 2 is opened, a rotating lever 14 is rotated by the energizing force of a spring 15, as well as a movable part 10a of a latch switch 10 is rotated while being pushed by an energizing part of a spiral spring 19. When the latch switch 10 is locked with a stopper 13b, the rotating lever 14 is separated from the movable part 10a, and thereafter the rotating lever 14 is separated from a movable part 12a of a monitor switch 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven in which a switch for controlling power supply to a heating member such as a magnetron is switched with opening and closing of a door.

[0002]

2. Description of the Related Art First, a general configuration of a vertical opening type microwave oven which is opened by turning an upper side of a door forward will be described. FIG. 8 is an external perspective view of the microwave oven, showing a state where the door 2 provided on the microwave oven main body 1 is opened. Door 2 is hinged to microwave oven body 1 (not shown)
And rotates in the direction of arrow A about the lower side of the door 2.

A front plate 4 is attached to the front surface of the microwave oven main body 1 along the periphery of the opening of the heating chamber 3, and the inside surface of the door 2 closed here is in close contact. The front plate 4 is provided with a through hole 4a at the upper right side in the figure. The inner surface of the door 2 is provided with a protrusion 2a,
Is closed, the projection 2a is fitted into the through hole 4a. An operation panel 5 is provided on the front surface of the microwave oven main body 1 adjacent to the door 2.

FIG. 9 is an electric circuit diagram of the microwave oven. FIG. 9 (a) shows the state when the door 2 is opened, and FIG. 9 (b) shows the state when the door 2 is closed. The magnetron 6 and the heater 7, which are heating members, are connected to a commercial power supply (not shown) via relay switches RY8 and RY9. A latch switch 10 and a fuse 11 are connected in series to these heating members 6 and 7, and a monitor switch 12 is connected in parallel.

As shown in FIG. 9A, when the door 2 is opened, the latch switch 10 is turned off and the monitor switch 12 is turned on. The power cannot be supplied to the heating members 6 and 7 by the latch switch 10 while the door 2 is open. When the door 2 is closed from this state, the monitor switch 12 is turned off first, and then the latch switch 10 is turned on (see FIG. 9B).

Then, the user operates the operation panel 5 (see FIG. 8).
When the start key is pressed, a control unit (not shown) turns on the relay switches RY8 and RY9, and power is supplied to the heating members 6 and 7 to start heating. When the heating is completed and the door 2 is opened, first, the latch switch 10 is turned off,
Thereafter, the monitor switch 12 is turned on.

The monitor switch 12 is provided to stop the operation of the heating members 6 and 7 when an accident such as contact welding occurs in the latch switch 10. That is, if the latch switch 10 is not turned off due to the welding of the contacts when the door 2 is opened, an overcurrent flows through the fuse 11 because the monitor switch 12 is on, and the fuse 11 is blown. Therefore, power is not supplied to the heating members 6 and 7.

A description will be given of a prior art of a configuration in which the latch switch 10 and the monitor switch 12 are turned on / off in conjunction with the opening / closing operation of the door 2. FIG. 10 is a schematic view of a part of the inside of the microwave oven main body 1 as viewed from above. In the figure, the downward direction is the front of the microwave oven, and the mounting plate 13 shown in this figure is located behind the operation panel 5 (see FIG. 8).

A latch switch 10 and a monitor switch 12, which are general micro switches, are fixed on the upper surface of the mounting plate 13 with screws. The rotating lever 14 made of resin is attached to be rotatable about a rotating shaft 13 a provided on the mounting plate 13. This rotating lever 14
Is biased counterclockwise about the rotating shaft 13a by a spring 15 and the front plate 4
The protrusion 14d of the rotary lever 14 fits into the through hole 4a.

When the door 2 is closed, the projection 2a (see FIG. 8) formed on the door 2 is fitted into the through hole 4a of the front plate 4, and pushes the projection 14d of the rotary lever 14 to rotate the rotary lever 14. Reference numeral 14 rotates clockwise about the rotation shaft 13a (indicated by a chain line 14 in the figure). Thereby, first, the rotating lever 1
In the fourth cam portion 14f, the movable portion 12a of the monitor switch 12 is pressed to turn off the contact. Thereafter, the cam portion 14e of the rotary lever 14 presses the movable portion 10a of the latch switch 10 to turn on the contact.

Next, when the door 2 is opened, the rotating lever 14 rotates counterclockwise around the rotating shaft 13a by the urging force of the spring 15, and returns to the original state. As a result, first, the movable portion 10a of the latch switch 10 is separated from the cam portion 14e of the rotary lever 14 and the contact is turned off. afterwards,
The movable part 12a of the monitor switch 12 is a rotary lever 14
Are separated from each other, and the contact is turned ON.

[0012]

In the above-mentioned prior art configuration, when the door 2 is completely closed and the door 2 and the front plate 4 are in close contact, the movable portion 10a of the latch switch 10 is completely retracted. The contact is turned ON. However,
Door 2 depends on the size of each member and the variation of the mounting position.
May not be in close contact with the front plate 4 and the contact of the latch switch 10 cannot be switched. Therefore, in order to reliably switch the contacts of the latch switch 10, the latch switch 10 must be provided at an appropriate position with respect to the rotary lever 14.

In order to mount the latch switch 10 at an appropriate position, a screw hole (not shown) of the mounting plate 13 is formed as a long hole in the prior art. The worker is the latch switch 1
A screw for fixing 0 is loosely fitted in the long hole, and first, the position of the latch switch 10 is adjusted according to the position of the rotary lever 14. Then, the screw is tightened to fix the position of the latch switch 10. However, this requires adjustment of the microwave ovens one by one, resulting in poor productivity.

In a microwave oven, when the temperature in the heating chamber 3 rises to near 300 ° C., the door 2 receives a force in the opening direction due to the expansion of the air in the heating chamber 3, and the door 2 and the front plate 4 are connected. There is a gap between them. In the prior art, the rotation lever 14 slightly rotates due to the gap, the latch switch 10 is turned off, and the power supply to the heating members 6 and 7 is interrupted.

The present invention has been made in consideration of the above problems, and is a microwave oven that does not require adjustment of a mounting position of a latch switch.
An object of the present invention is to provide a microwave oven in which a contact of a latch switch does not change even when a door is slightly opened.

[0016]

In order to solve the above-mentioned problems, a microwave oven according to claim 1 is a microwave oven which is opened by lowering an upper side of a door of a heating chamber toward the front, and is heated when the door is opened. The first and second switches, which do not supply power to the member, move in one direction when the door is closed, press the movable parts of the first and second switches, and when the door is opened, move in the opposite direction. A switch switching member that moves to cancel the pressing of the movable portions of the first and second switches,
A first switch connected in series with the heating member and the fuse, and a second switch connected to the heating member in parallel with the microwave oven, wherein the first switch is rotatable about an axis; A first urging means for urging the first switch in a direction in which the movable portion of the switch comes into contact with the switch switching member is provided.

According to the above configuration, when the door is closed, the movable portions of the first and second switches are pressed by the switch switching member. When the door is opened, the switch switching member moves in the opposite direction. At this time, the first
The switch is rotated about an axis by the urging force given by the first urging means while the movable portion is in contact with the switch switching member.

According to a second aspect of the present invention, in the microwave oven according to the first aspect, a first switch and a switch switching member are respectively mounted on the upper surface so as to be rotatable about an axis, and the second switch is fixed. Mounting plate,
Drive means for rotating the switch switching member in the one direction when the door is closed, second biasing means for biasing the switch switching member in the opposite direction, and first rotating by the first biasing means. And a stopper for locking the switch.

When the door is closed, the movable portion of the first switch is pressed after the movable portion of the second switch is pressed by the rotation of the switch switching member, and the first switch is separated from the stopper. When the door is opened, the first switch rotates with the rotation of the switch switching member and locks to the stopper, and the switch switching member is separated from the movable portion of the second switch after being separated from the movable portion of the first switch. It is characterized by doing.

In the microwave oven having the above-mentioned structure, when the door is closed, the switch switching member is rotated about the axis by the driving means in the one direction, and firstly presses the movable portion of the second switch, and thereafter the first switch is pressed. Press the movable part of the switch.
Then, the first switch locked by the stopper is further pressed to separate from the stopper.

When the door is opened, the switch switching member is rotated in the opposite direction by the urging force of the second urging means. Since the first switch is urged by the first urging means, the first switch is rotated together with the movable portion while contacting the switch switching member, and is locked by the stopper. Then, the switch switching member is separated from the movable portion of the first switch, and then separated from the movable portion of the second switch.

The microwave oven according to claim 3 is the first or second microwave oven.
3. The microwave oven according to claim 1, wherein a film having electrical insulation and low friction is adhered to a sliding range of the first switch and a connection terminal provided on the first switch on the mounting plate. I do. Therefore, the first switch will slide on this film.

[0023]

Embodiments of the present invention will be described with reference to the drawings. The appearance of the microwave oven and the configuration of the electric circuit according to this embodiment are the same as those shown in FIGS. 8 and 9 shown in the prior art, and FIGS.
Members having the same names as those described above are denoted by the same reference numerals, and redundant description will be omitted.

A first embodiment according to the present invention will be described. 1 and 2 are schematic diagrams showing a partial configuration of the inside of the microwave oven main body according to the present embodiment. FIG. 1 shows a state where the door 2 is opened, and FIG. 2 shows a state where the door 2 is closed. In the figure, a space 1a in the microwave oven main body in which the latch switch 10 and the like are provided is located behind the operation panel 5, and a heating chamber (not shown) (see FIG. 8) is located on the left side of the space 1a in the figure. To position.

As shown in FIG. 1, one side of the mounting plate 13 is fixed to the wall 1b of the microwave oven body 1 with screws 16. The rotating lever 14 on the mounting plate 13 is a box, and has a hole 14a on the bottom surface. A rotary shaft 13a protruding from the upper surface of the mounting plate 13 is fitted into the hole 14a, and the rotary lever 14 can freely rotate the surface of the mounting plate 13 about the rotary shaft 13a.

A claw 14c is provided on a wall 14b inside the rotary lever 14.
One end of the spring 15 is fixed, and the other end is fixed to the front surface of the microwave oven main body 1. This spring 1
5, the rotation lever 14 is biased counterclockwise about the rotation shaft 13a. Further, a convex portion 14 d is provided on one side surface of the rotary lever 14, and is fitted in a through hole 4 a formed in the front plate 4.

The latch switch 10 and the monitor switch 12 are mounted on the mounting plate 13. FIG. 3 is an external perspective view of the latch switch 10. Reference numeral 10a denotes a movable portion for switching a contact of a switch. When the movable portion 10a is immersed, the contact is turned on, and when the movable portion 10a is projected, the contact is turned off. Holes 10b and 10c penetrating the main body of the latch switch 10 in the height direction are provided at diagonal positions, and connection terminals 10d for connecting to other electric members are provided on side surfaces.

FIG. 4 is a perspective view of the latch switch 10 mounted on the mounting plate 13 as viewed from the rear of the microwave oven. FIG. 5 is a side view of the latch switch 10 viewed from the front of the microwave oven. Hole 10 of latch switch 10
A stepped screw 17 is fitted in b (see FIG. 3), and the tip of the stepped screw 17 is fixed to the mounting plate 13.
The diameter of the hole 10b is larger than the diameter of the screw portion of the stepped screw 17, and the latch switch 10 is connected to the stepped screw 1
7 can be freely rotated.

A pin 18 is inserted into the other hole 10c of the latch switch 10. A cut is formed at the upper end of the pin 18, and one end of a spiral spring 19 is hooked there. The mounting plate 13 is made of a steel plate, and forms a bent portion 13b by vertically extending a stretched portion. A hole 13c is provided in the upper part of the bent portion 13b, and the other end of the spiral spring 19 is hooked on the hole 13c.

A stopper 13d is provided on the mounting plate 13 between the latch switch 10 and the bent portion 13b. Similarly to the bent portion 13b, the stopper 13d is formed by bending a part of the mounting plate 13 vertically. The latch switch 10 is provided with a stepped screw 1 by the helical spring 19.
An urging force that rotates in the direction of arrow B around the center 7 is applied, but the rotation is restricted by contacting the stopper 13d. The bent portion 13b and the stopper 13d are attached to the mounting plate 1
Since the microwave oven is processed by cutting and raising in step 3, the microwave oven of the present embodiment is economically constructed.

The monitor switch 12 has the same configuration as the latch switch 10 shown in FIG.
(See FIG. 3). The movable switch 12a is also provided on the side surface of the monitor switch 12, and the contact is turned off when the movable part 12a is immersed, and turned on when the movable part 12a is protruded.

Next, a switching operation associated with opening and closing of the door 2 will be described. As shown in FIG. 1, when the door 2 is opened, the protrusion 14 d of the rotary lever 14 is fitted into the through hole 4 a of the front plate 4 by the urging force given by the spring 15. The latch switch 10 is in contact with the stopper 13d by the urging force given by the spiral spring 19,
The movable portion 10a is provided on the side of the rotary lever 14 (the cam portion 14
e). Therefore, the contact of the latch switch 10 is OFF. The monitor switch 12
The movable portion 12a is a side surface of the rotary lever 14 (cam portion 14f).
, But the contact is ON because it is pressed.

From this state, the door 2 is closed. As shown in FIG. 2, when the door 2 is closed, the protrusion 2 a of the door 2 is fitted into the through hole 4 a of the front plate 4. Thereby, the convex portion 14d of the rotary lever 14 fitted in the through hole 4a in FIG. 1 is pushed in, and the rotary lever 14 rotates clockwise about the rotary shaft 13a.

When the rotation of the rotary lever 14 starts, the cam portion 14f of the rotary lever 14 slides with respect to the movable portion 12a of the monitor switch 12. When the curved position 14f 'of the cam portion 14f exceeds the movable portion 12a, the cam portion 1
The movable part 12a is immersed by 4f. Therefore, the contact of the monitor switch 12 is turned off.

Thereafter, the cam portion 14e is further moved by the rotation of the rotary lever 14 so that the movable portion 1
0a and is pressed. Then, while the movable part 10a is pressed, the latch switch 10 is
7 rotates counterclockwise to separate from the stopper 13d. Latch switch 10 with movable part 10a pressed
Turns on the contact. At this time, the distance from the latch switch 10 to the stopper 13d is about several millimeters.

Next, when the closed door 2 is opened, the projecting portion 2a of the door 2 is detached from the through hole 4a of the front plate 4, and the rotating lever 14 is returned to its original position (convex portion 14d) by the urging force of the spring 15. Is fitted into the through hole 4a). Therefore, the rotation lever 14 rotates counterclockwise about the rotation shaft 13a.

When the rotation of the rotary lever 14 starts, the latch switch 10 rotates clockwise around the stepped screw 17 while the movable portion 10a is pressed by the cam portion 14e of the rotary lever 14 by the urging force of the helical spring 19. To rotate.
When the latch switch 10 comes into contact with the stopper 13d and stops, the cam portion 14e of the rotary lever 14 separates from the movable portion 10a of the latch switch 10, and the movable portion 10a
Is released. Thereby, the latch switch 1
The 0 contact is turned off.

With the rotation of the rotary lever 14, the cam portion 14
f is sliding with respect to the movable part 12a of the monitor switch 12. After the pressing of the movable portion 10a of the latch switch 10 is released, the curved position 14f 'of the cam portion 14f exceeds the movable portion 12a, and the movable portion 12a of the monitor switch 12 is moved.
Is released. Thereby, the contact of the monitor switch 12 is turned ON.

In a microwave oven, when the temperature in the heating chamber rises due to the operation of the magnetron and the heater, a force is generated in the opening direction of the door 2 by the expanded air, and a gap is generated between the door 2 and the front plate 4. According to the above-described configuration of the present embodiment, when a gap is generated between the door 2 and the front plate 4, the rotation lever 14 rotates slightly counterclockwise about the rotation shaft 13a.

At this time, the latch switch 10 is actuated by the biasing force of the spiral spring 19 so that the cam portion 14e of the rotary lever 14 is moved.
And the movable portion 10a is rotated together with being pressed. Therefore,
The contact of the latch switch 10 cannot be switched. Of course, the monitor switch 12 also keeps the movable portion 12a pressed, and the contact is not switched. Therefore, the inconvenience that the latch switch 10 is turned off by the slight opening of the door 2 and the heating member stops during the heating of the food unlike the related art does not occur.

According to the microwave oven of this embodiment,
The rotation lever 1 is always within the rotation range of the latch switch 10.
4, the movable portion 10a is pressed. Therefore, even if the door 2 is not in close contact with the front plate 4 when the door 2 is closed due to variations in dimensions and mounting positions of the respective members, if the variations fall within the rotation range of the latch switch 10, the latch switch The movable part 10a of 10 can be sufficiently pressed. Therefore, it is not necessary to adjust the position of the latch switch 10 as in the related art, and it is possible to perform a work with high productivity.

Next, a second embodiment according to the present invention will be described. In this embodiment, a resin film is provided between the latch switch 10 and the mounting plate 13 in the first embodiment. FIG. 6 shows the latch switch 1 mounted on the mounting plate 13 in the microwave oven according to the present embodiment.
0 is a perspective view of the microwave oven viewed from the back of the microwave oven. FIG.
Is a side view of the latch switch 10 as viewed from the front of the microwave oven.

On the upper surface of the mounting plate 13, an electrically insulating and low friction film 21, such as a polyester film, is adhered. The size of the film 21 includes the sliding range of the latch switch 10 and the moving range of the connection terminal 10d. Accordingly, the electrical performance is satisfied even if the insulation distance between the connection terminal 10d and the mounting plate 13 is short due to a wiring failure of the latch switch 10, or the like.
Further, the rotation of the latch switch 10 is performed smoothly.

[0044]

As described above, in the microwave oven according to the first and second aspects, even if a gap is formed between the door and the front plate due to a variation in the dimensions of the members or the mounting position, the variation is absorbed. As a result, the contact of the latch switch is reliably switched. Therefore, the work of adjusting the position for mounting the latch switch becomes unnecessary. In addition, since the latch switch is not switched even if a force that opens the door is generated during the heating of the food, the operation of the heating member is continued normally, and there is no inconvenience that the latch switch is turned off halfway.

In particular, in the microwave oven according to the second aspect, the movable area of the latch switch is reduced by providing a stopper. As a result, problems during the operation of the latch switch, for example, a situation in which dust is jammed and cannot be moved can be reduced. Further, the expansion and contraction ratio of the helical spring as the urging means can be reduced, and stable operation of the latch switch can be achieved.

In the microwave oven according to the third aspect, by providing a film having electrical insulation and low friction between the first switch and the mounting plate, first, the sliding performance of the latch switch is improved. The load applied to the helical spring as the biasing means is reduced, and a stable operation can be obtained.

Further, since the film is provided also in the moving range of the connection terminal of the latch switch, the electric performance is satisfied even when the mounting plate is made of a conductive material. In addition, even if a lightning surge or the like is superimposed on the latch switch, no discharge occurs between the connection terminal and the mounting plate. Therefore,
The problem that a control unit such as a microcomputer that controls the operation of a microwave oven may malfunction can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a partial configuration inside a microwave oven body according to a first embodiment when a door is opened.

FIG. 2 is a schematic diagram showing a partial configuration of the inside of the microwave oven body according to the first embodiment when the door is closed.

FIG. 3 is an external perspective view of a latch switch.

FIG. 4 is a perspective view showing a mounting state of a latch switch.

FIG. 5 is a side view showing a mounting state of the latch switch.

FIG. 6 is an exemplary perspective view showing a mounting state of a latch switch in the microwave oven according to the second embodiment;

FIG. 7 is an exemplary side view showing a mounting state of a latch switch in the microwave oven according to the second embodiment;

FIG. 8 is an external perspective view of a microwave oven.

FIG. 9 is an electric circuit diagram of a microwave oven.

FIG. 10 is a schematic diagram showing a partial configuration inside a main body of a conventional microwave oven.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave oven main body 2 Door 2a Projection part 10 Latch switch 10a Movable part 12 Monitor switch 12a Movable part 13 Mounting plate 13d Stopper 14 Rotary lever 15 Spring 19 Spiral spring 21 Film

Claims (3)

[Claims] 1. A microwave oven which is opened by lowering an upper side of a door of a heating chamber toward the front, wherein first and second switches which do not supply power to a heating member when the door is opened,
When the door is closed, it moves in one direction to press the movable parts of the first and second switches, and when the door is opened, it moves in the opposite direction to the one and the second switch. A switch switching member for canceling the pressing of the movable portion, wherein the first switch is connected in series with the heating member and the fuse, and the second switch is connected in parallel with the heating member. In the first aspect, the first switch is rotatable about an axis, and a first urging means for urging the first switch in a direction in which a movable portion of the first switch comes into contact with the switch switching member. A microwave oven characterized by being provided with. 2. When the first switch and the switch changeover member are mounted on the upper surface so as to be rotatable about respective axes and the second switch is fixed, and the door is closed. Drive means for rotating the switch switching member in the one direction; second urging means for urging the switch switching member in the opposite direction; and the first switch rotated by the first urging means. A stopper that locks the movable portion of the first switch after the movable portion of the second switch is pressed by the rotation of the switch switching member when the door is closed. The first switch is separated from the stopper, and when the door is opened, the first switch rotates together with the rotation of the switch switching member and locks on the stopper, The microwave oven according to claim 1, wherein the switch switching member is separated from the movable portion of the second switch after being separated from the movable portion of the first switch. 3. A film having an electrical insulating property and a low friction property is adhered on the mounting plate in a sliding range of the first switch and a connection terminal provided on the first switch. The microwave oven according to claim 1 or 2, wherein