JPS5825587Y2 - High frequency heating device - Google Patents

Description

[Detailed explanation of the invention] This invention uses a rotating mounting table (turntable) on the bottom wall of the heating chamber.
The present invention relates to a high-frequency heating device, a so-called microwave oven, and is intended to prevent radio wave leakage in a bearing for driving a rotary mounting table.

A microwave oven uses high frequency waves of around 2450 MHz to cook food, and as shown in Figure 1, the microwave oven
A heating chamber 2 is provided inside the heating chamber, and a magnetron 3 that emits high frequency waves is installed inside this heating chamber.

There is also a door 4 that opens and closes the front opening of the heating chamber. A door handle 5 for opening and closing the door 4, a see-through window 6 for viewing the heating chamber
etc.

Further, as a means for reducing heating unevenness in the heating chamber, a stirrer 8 attached to the stirrer shaft 7, a rotary mounting table 10 (saucer) for rotating the food 9, and a motor 11 for driving the rotary tray. a transmission shaft 12 that transmits the rotational force of the motor to the receiver;
A roller 13 and the like that slide on the circumference of the saucer are provided.

Note that 14 is a plate that partitions the heating chamber 2 and the starch hanger mounting section.

FIG. 2 is an enlarged sectional view of section A in FIG. 1, and this section will be explained below.

Generally, when the motor 11 is rotated at a commercial frequency, the rotational speed becomes high and it is inconvenient to connect it directly to a turntable, so the speed is reduced to about 10 rotations using a gear.

Therefore, when a voltage is applied to the motor terminal 15, the rotor of the motor rotates and is decelerated by the gear housed in the gear box 16, and its output shaft 17 rotates.

In addition, 18 is a motor core, 19 is a coil bobbin, 20 is a rotor bearing, and this geared motor has a motor mounting plate 21.
is attached to the bottom wall 22 of the heating chamber.

A flat plate 23 is fixed to the end of the output shaft 17, and this flat plate 23 is connected to a groove 24 of the transmission shaft 12, which is provided with a groove at the bottom.
, the transmission shaft 12 is rotated, and the convex part 25 on the upper part of the transmission shaft engages with the concave part 26 of the rotary saucer 10, so that the rotary saucer 1
0 rotates on roller 13.

The transmission shaft 12 is installed between the bearings 21 via Teflon washers 28 and 29 that reduce frictional resistance, and after the metal washers 30 are inserted, a retaining ring 31 prevents the transmission shaft 12 from coming off upward.

The bearing 27 is fixed to the bottom wall 22 of the heating chamber in a groove thereof with a screw 33 via a packing rubber 32.

Further, the rotating tray 10 is made of glass, the transmission shaft 12 is made of synthetic resin, and the bearing 27 is made of die-cast aluminum or the like.

Furthermore, a main body bottom plate 34 is installed at the bottom of the motor to protect the motor and protect the bearing 27 and transmission shaft 1 from water spilling in the heating chamber.
A drainage hole 35 is provided so that water that has passed through the room can drain out.

What is shown in FIGS. 3 and 4 are sectional views showing a conventional example, and since the bottom wall surface 22 of the heating chamber is made of sheet metal, it is extremely difficult to make it completely flat.

As shown in FIG. 3, when the bearing 27 is fixed to the peripheral edge 22a of the through hole of the bearing for driving the rotary mounting table, sag that creates a gap is likely to occur.

Figure 4 shows the state in which the bearing 27 is tightened and fixed to the bottom wall 22 of the heating chamber with screws 33, and there is a gap at the periphery of the through hole 22H, which is an important electrical contact area for preventing radio wave leakage. This causes a large amount of radio waves to leak as shown by the arrow.

FIG. 5 shows an embodiment of the present invention, which differs from the conventional example in that the bottom wall surface 22 of the heating chamber is intentionally sloped in the direction of lifting the bearing 27, so that the periphery 22a of the through hole is placed earlier than the other parts. This makes it possible to eliminate leakage of radio waves from the peripheral edge 22a of the through hole.

Note that although FIG. 5 shows the state in which the screw 33 is not completely tightened, when the screw 33 is completely tightened, the bottom wall 22 of the heating chamber is elastically deformed and the periphery of the through hole 22a is caused by the spring effect. A stronger adhesion between the bearings 27 can be achieved.

The present invention provides the heating chamber bottom wall surface 22 with an incline or a protrusion so that the portion of the heating chamber bottom wall surface 22 that requires close contact with the bearing 27, which is necessary for preventing radio wave leakage, contacts preferentially over other portions. However, as in the embodiment shown in FIG. 5, the bottom wall surface 22 of the heating chamber is sloped or protruded in the direction of lifting the bearing 27 so that the peripheral edge 22a of the through hole comes into preferential contact with the bearing 27. By doing so, the contact area between the bearing 27 and the heating chamber wall surface 22 necessary to prevent radio wave leakage can be minimized, and the possibility of radio wave leakage can be further reduced.

As is clear from the conceptual diagram of the contact surfaces in Figure 6, the contact area required to obtain the same contact width is greater in the case of A, where the contact is closer to the inside, than in the case of B, where the contact is closer to the outside. is the contact area S1 for A, and the contact area S2 for B
It takes less than that.

That is, since it is the contact width mentioned above that influences the value of radio wave leakage, if this value is made the same, the conditions for radio wave leakage will be the same.

Therefore, the smaller the required contact area, the more reliable it can be because it will not be affected by unstable factors due to various variations.

As explained above, according to the present invention, the following effects can be expected.

1. It is possible to prevent leakage of radio waves from the mounting part of the rotary mounting table bearing due to variations in processing of the bottom wall of the heating chamber.

2. The elastic deformation of the heating chamber bottom wall allows the bearing and the heating chamber bottom wall to be brought into closer contact with each other, which is effective in preventing radio wave leakage.

32, the same effect as using a spring washer for the bearing fixing screw can be obtained, so that the screw can be prevented from falling off.

In relation to 41, processing accuracy (flatness) of the heating chamber wall is no longer required as in the past, and processing becomes easier and costs can be reduced.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional high-frequency heating device;
The figure is an enlarged sectional view of part A in FIG. 1, FIGS. 3 and 4 are sectional views of the main bearing through hole portion, and FIG. 5 is a sectional view of the same part showing an embodiment of the present invention. FIG. 6 is a top view of the same part. 22... Heating chamber bottom wall, 22 a... Through hole, 27... Bearing.

Claims (1)

[Scope of utility model registration request] A high-frequency heating device having a structure in which a bearing for driving a rotating mounting table is provided on the inner bottom wall of the heating chamber, and a slope or protrusion is formed on the periphery of a bearing through hole in the bottom wall of the heating chamber to which the bearing is fixed in a direction in which the bearing is lifted. .