JPH08110056A - Microwave oven - Google Patents

Abstract

PURPOSE: To make it possible to connect definitely an outside ground wire to a ground terminal with ease and reduce a manufacturing cost as well. CONSTITUTION: In a device provided with a noise filter based on a ground inductor system, an insulated plastics-made holder 43, which is designed to hole a ground inductor 37, which constitutes a part of the noise filter, is installed to a rear board 13 of an exterior wall of an oven main body 11 where a ground board 46, to which one terminal 39b of a winding 39 of the ground inductor 37 is connected, is mounted to the holder 43 and a threaded hole 46c, which locks a connection terminal 50 of the outside ground wire 20, is installed to the ground board 46 in this structure. In the case of this structure, it is possible to fasten the screw 51 with a standard screwdriver when screwing the outside earth wire 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven provided with a ground inductor type noise filter.

[0002]

2. Description of the Related Art Generally, in a microwave oven, a ground terminal is provided on the rear surface of the outer wall of the range body, and an external ground wire is connected to the ground terminal when the microwave oven is installed. I have to. In a microwave oven, noise generated in the internal electric circuit may propagate to the external AC power source side through the power supply line and adversely affect other electric devices. A filter is provided. In this case, for example, in a microwave oven that employs a ground inductor type noise filter, the inductance element that forms a part of the noise filter is placed between the ground terminal and the metal plate of the range body (so-called body ground ground terminal). Connected to.

In this structure, since it is necessary to insulate the earth terminal from the metal plate portion of the range main body, the earth terminal is arranged in a holder made of an insulating material for holding the inductance element. . FIG. 11 shows an example of the ground terminal having such a configuration. In FIG. 11, a holder 1 made of insulating plastic for holding an inductance element is attached to a rear plate 2 which is a metal plate portion of a range main body. Through holes 3 are formed in the holder 1,
Further, the hexagonal nut 4 is housed in the hexagonal large-diameter portion 3a formed on the outer side portion of the through hole 3. The long screw 5 is inserted from the inside into the through hole 3 via the spring washer 6 and is fastened to the hexagon nut 4. In this case, the connection terminal 7a provided at the end of one lead wire 7 led from the winding of the inductance element is sandwiched between the head 5a of the long screw 5 and the spring seat 6. It is configured.

On the other hand, the end portion of the long screw 5 has a hexagonal nut 4
The connection terminal 8a provided at the end portion of the external ground wire 8 is connected to the protruding portion. Specifically, the connecting terminal 8a of the external ground wire 8 is sandwiched between the hexagonal nut 9 for connection and the hexagonal nut 4, and is tightened and fixed.

[0005]

In the above-mentioned conventional configuration, when the microwave oven is installed at home or the like, the connection screw 8a of the external ground wire 8 must be connected to the long screw 5 of the ground terminal. In this case, it is necessary to perform the work of tightening the hexagon nut 9 for connection. Since this tightening work requires a special tool such as a spanner or box driver which is not provided in general households, it is difficult to connect the external ground wire 8 to the ground terminal. there were. Further, since the conventional ground terminal requires the long screw 5 made of brass which is quite long, there is also a drawback that the manufacturing cost becomes high.

Therefore, an object of the present invention is to easily perform the work of connecting an external ground wire to the ground terminal, and
An object is to provide a microwave oven which can reduce the manufacturing cost.

[0007]

The microwave oven of the present invention comprises:
In a microwave oven provided with a ground inductor type noise filter, a holding member made of an insulating material that is attached to an outer wall of a range main body and holds an inductance element that constitutes a part of the noise filter is attached to the holding member. And a ground plate to which one terminal of the winding of the inductance element is connected, and a screw hole for screwing a connection terminal of an external ground wire provided on the ground plate.

Further, in the above structure, the structure for attaching the ground plate to the holding member is provided so as to sandwich the ground plate on the holding member, and the ground plate is moved in a direction orthogonal to the plate surface of the ground plate. Regulating part for regulating the screw, a screw hole provided in the ground plate, and a screw that is screwed into the screw hole and is connected by screwing one terminal of the winding of the inductance element to the ground plate. And a restriction hole provided to insert the screw into the holding member and restricting movement of the ground plate in a direction along the plate surface of the ground plate.

[0009]

According to the above means, the earth plate is attached to the holding member made of an insulating material for holding the inductance element forming a part of the noise filter, and one terminal of the winding of the inductance element is connected to the earth plate. Since the ground plate has a screw hole for screwing the connection terminal of the external ground wire, when connecting the external ground wire to the ground terminal, screw the external ground wire into the screw hole of the ground plate. Just do it. In this case, the connection work can be performed easily because the screws are only tightened with an ordinary screwdriver. Also, since the ground plate is simply provided with a screw hole,
The manufacturing cost is lower than that of the conventional configuration that requires long screws.

Further, in the above structure, the holding member is provided so as to sandwich the earth plate, and the restricting portion for restricting the movement of the earth plate in the direction orthogonal to the plate surface of the earth plate and the screw provided on the earth plate are provided. Hole, a screw that is screwed into this screw hole and that connects one terminal of the winding of the inductance element to the ground plate by screwing, and a screw that is provided to insert the screw into the holding member. A regulation hole for regulating the movement of the ground plate in the direction along the plate surface is provided, and the ground plate is attached to the holding member by these. Thus, when the ground plate is mounted on the holding member, the screw for connecting one terminal of the winding of the inductance element to the ground plate by screwing can be used for both connection and mounting, so that the mounting structure can be simplified. At the same time, the mounting work can be easily performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a microwave oven with a heater will be described below with reference to FIGS. First, in FIG. 2 showing a schematic external view of a microwave oven with a heater, a range main body 11 forming an outer shell of the microwave oven has a rectangular box shape as a whole, and a cooking chamber (not shown) is provided inside. It is provided. The range main body 11 includes a cabinet 12 and a rear plate 13 which are substantially U-shaped so as to cover the upper surface and both side surfaces.
And a bottom plate (not shown). The cabinet 12, the rear plate 13 and the bottom plate are made of metal plates. Further, a door 14 for opening and closing a front opening of the heating and cooking chamber is provided on the front surface of the range main body 11 so as to be opened and closed.

Further, a machine room (not shown) is provided on the right side of the heating and cooking room in the range main body 11, and a magnetron 15 for range cooking is provided in the machine room.
(See FIG. 8) is provided. This magnetron 15
By supplying the high frequency (microwave) oscillated from the heating cooking chamber into the heating cooking chamber, range cooking is performed in the heating cooking chamber. Further, as shown in FIG. 2, an operation panel 16 is provided on the front surface of the range main body 11 on the front side of the machine room. The operation panel 16 is provided with various switch keys and various indicators. It should be noted that a large number of electric parts constituting the electric configuration of the microwave oven are arranged in the machine room.

On the other hand, the heater 1 is installed on the ceiling of the cooking chamber.
7 (see FIG. 8) is provided, and heating by the heater 17 is used to perform heater cooking such as oven cooking and grill cooking in the heating cooking chamber. The heater 17 is composed of, for example, a flat heater, a glass tube heater, a sheath heater, or the like. A heater may be provided at the bottom of the cooking chamber. Further, it is also preferable to provide a hot air supply device for supplying hot air into the cooking chamber.

A ground terminal 18 for external ground connection is provided at the lower left end of the rear plate 13 (the end opposite to the machine room). As shown in FIG. 1, the earth terminal 18 is a terminal for connecting to an earth ground, for example, an earth rod 19 embedded in the ground through an external earth wire 20, and the earth terminal 18 is specifically described. The peripheral structure will be described later. Further, a ground terminal 21 of the range main body 11 is provided at a position slightly above the ground terminal 18 in the flange portion at the left end of the rear plate 13. The ground terminal 21 is a so-called body ground terminal, and is composed of a screw hole formed in the rear plate 13 and a screw 22 screwed into the screw hole.

Next, the electrical configuration of the microwave oven will be described with reference to FIG. In FIG. 8, the terminals 23a, 24a on one side of the pair of power supply lines 23, 24 are
It is connected to a commercial AC power source. A fuse 25 and a first door switch 26 are provided in series on one of the pair of power supply lines 23, 24. A second door switch 27 is provided on the other power supply line 24. In addition, the power supply lines 23, 2
A short switch 28 is connected between the four. The first door switch 26 and the second door switch 27 are
It is a switch that operates so as to be turned off and on in association with opening and closing of the door 14. The short switch 28 includes the first door switch 26 and the second door switch 2
7 is an on / off operation opposite to the on / off operation of FIG.

Further, a series circuit composed of the heater 17 and a heater relay 29 is provided between the power supply lines 23 and 24 on the side opposite to the power supply side of the door switches 26 and 27.
A primary winding 30a of a high voltage transformer (step-up transformer) 30 and a series circuit including a magnetron relay 31 are connected in parallel. A series circuit including a diode 32 and a capacitor 33 having the illustrated polarities is connected between both terminals of the secondary winding 30b of the high voltage transformer 30.
The cathode of the diode 32 is connected to the cathode of the magnetron 15, and the anode of the diode 32 is connected to one terminal of the anode of the magnetron 15. The cathode of the magnetron 15 is the ground terminal 2 of the range body 11.
Connected to 1. Further, both terminals of the anode of the magnetron 15 are connected to both terminals of the secondary winding 30c of the high voltage transformer 30. In this case, the diode 32 and the capacitor 33 form a voltage doubler rectifier circuit.

On the other hand, a first capacitor 34 and a second capacitor 35 are provided between the power supply lines 23 and 24 and between the door switches 26 and 27 and the series circuit including the heater 17 and the heater relay 29. And a series circuit including the third capacitor 36 are connected in parallel. These three capacitors 34 to 36 form a part of the noise filter. The common connection point A between the second capacitor 35 and the third capacitor 36 is connected to the ground terminal 21 of the range body 11. As a result, the second capacitor 35 is connected between the one power supply line 23 and the ground terminal 21 of the range body 11,
The capacitor 36 is connected between the other power supply line 24 and the ground terminal 21 of the range main body 11.

Further, the earth terminal 21 of the range body 11
, And an earth terminal 18 to which the external earth wire 20 is connected, an earth inductor 37, which is an inductance element forming a part of the noise filter, is connected. The earth inductor 37 is configured by winding a winding 39 around a core 38 made of a ferrite ring (see also FIG. 1). Then, one end 39a of the winding 39 is connected to the ground terminal 21 of the range main body 11, and the other end 39b is connected.
Is connected to a ground terminal 18 for connecting an external ground wire 20. In this case, the noise filter 40 is composed of the ground inductor 37 and the three capacitors 34 to 36. The noise filter 40 has a well-known configuration called a so-called earth inductor type noise filter. Then, the noise filter 40 is connected to the relay 2
It has a function of attenuating the noise generated by each operation of 9, 31, the high voltage transformer 30, the magnetron 15, etc. and propagating to the external commercial AC power source through the power source lines 23, 24 (power cord).

Further, the heater relay 29 and the magnetron relay 31 are each configured to be on / off controlled by a control circuit 41. The control circuit 41 is mainly composed of a microcomputer and stores a control program for controlling the entire cooking operation of the microwave oven. The control circuit 41 has a DC voltage circuit for supplying a DC constant voltage to a built-in microcomputer or the like. The primary winding 42 of the power transformer 42 that constitutes a part of this DC voltage circuit
Both terminals of a are connected to a portion between the fuse 25 and the first capacitor 34 between the power supply lines 23 and 24.

Now, the structure of the ground terminal 18 for external ground connection will be described in detail with reference to FIGS. 1 and 3 to 7. First, in FIG. 1, a holder 43 as a holding member for holding the earth inductor 37 is formed of an insulating material such as insulating plastic, and is attached to the rear plate 13 of the range main body 11. As shown in FIG. 3, the holder 43 has a board portion 44 extending in the vertical direction and a holding portion 45 provided in the upper half of the board portion 44. It is configured to accommodate and hold the earth inductor 37. The holding portion 45 has a substantially rectangular box shape, and the right side surface and the lower side surface in FIGS. 1 and 2 are open. Then, as shown in FIGS. 3 and 4, a holding claw 45b for holding the ground inductor 37 is formed on one side wall portion 45a of the holding portion 45.

Further, as shown in FIG. 1, a mounting portion 47 for mounting and holding the earth plate 46 is formed on the substrate portion 44 of the holder 43. The mounting portion 47 includes a concave portion 47a formed on the upper left surface portion of the substrate portion 44 in FIG.
A recess 47b formed in the lower right surface portion of the substrate portion 44 in FIG.
It consists of and. Two claw portions 47c (see FIG. 5) that project from the middle portion of the recess 47a and engage with the upper end portion 46a (see FIG. 6) of the ground plate 46 to sandwich the upper end portion 46a are provided. . In addition, one claw portion 47d (see FIG. 1) that engages with the lower end portion 46b of the ground plate 46 and clamps the lower end portion 46b is provided at the lower end portion of the recess 47b. In this case, the recesses 47a, 47b and the claws 47c, 47d are configured to restrict the movement of the ground plate 46 in the direction orthogonal to the plate surface of the ground plate 46 (the horizontal direction in FIG. 1). These recesses 47a,
47b and the claw portions 47c and 47d form a regulation portion.

On the other hand, in the middle portion of the earth plate 46,
As shown in FIG. 6, two screw holes 46c and 46d are formed vertically. The upper screw hole 46c is, for example, burred and protrudes rightward in FIG. The lower screw hole 46d is, for example, burred and protrudes leftward in FIG. And each screw hole 46c, 46d
A female screw is formed on each of the taps.

Here, the terminal 39c provided on the other end 39b of the winding 39 of the earth inductor 37 is connected to the lower screw hole 46d by being tightened and fixed by the screw 48. (See FIG. 1).
A fitting hole 49a for fitting the tip of the screw 48 is formed in the recess 47b of the substrate portion 44 of the holder 43. In this case, the tip portion of the screw 48 has the fitting hole 4
By being fitted in 9a, movement of the ground plate 46 in the direction along the plate surface of the ground plate 46 (vertical direction in FIG. 1) is restricted, and the fitting hole 49a is a restriction hole. Are configured. In order to form the fitting hole 49a, a convex portion 49 is provided on the substrate portion 44 so as to project leftward in FIG.

Further, the screw hole 46c on the upper side of the ground plate 46
The connection terminal 5 provided at the end of the external ground wire 20.
0 is connected by being fastened and fixed by screws 51 (see FIG. 1). In this case, the screw hole 46c on the upper side of the ground plate 46 is connected to the external ground wire 20.
The ground terminal 18 for connection is configured. The holder 4
A fitting hole 52a for fitting the tip end portion of the screw 51 is formed in the recess 47a of the base plate portion 44 of No. 3. Further, in order to form the fitting hole 52a, the convex portion 52 is provided on the substrate portion 44 so as to project rightward in FIG.

On the other hand, as shown in FIG. 1, an engaging claw 44a is provided on the upper end portion of the substrate portion 44 of the holder 43 so as to project upward. By engaging the engaging claw 44a with the upper opening edge of the rectangular through hole 13a formed in the rear plate 13, and by fixing the lower end 44b of the base plate portion 44 to the rear plate 13 with the screw 53. The holder 43 is attached and fixed to the rear plate 13. Then, in this mounted state, the screw hole 4 of the ground plate 46 that constitutes the ground terminal 18
6c is configured to be exposed to the outer surface side through the through hole 13a.

In the case of the above configuration, the ground inductor 37
Is attached to the rear plate 13 which is the outer wall portion of the range main body 11 via the holder 43. The earth inductor 37 and the rear plate 13 of the range main body 11 are insulated by a holder 43 made of insulating plastic.

The ground plate 46 is attached to the mounting portion 4 of the holder 43.
7, the lower end of the ground plate 46 is attached to the mounting portion 47 from above the left side of the substrate portion 44 of the holder 43 in FIG.
While inserting the ground plate 46 into the recess 47b of the recess 4b.
7a and 47b (see FIG. 7). Subsequently, the ground plate 46 is slid downward to engage the upper end portion 46a of the ground plate 46 with the two claw portions 47c and the lower end portion 46b of the ground plate 46 with the claw portion 47d (Fig. 1). After this, the screw hole 46d of the ground plate 46
Then, the terminal 39 c of the winding 39 of the ground inductor 37 is tightened and fixed by the screw 48. As a result, the ground plate 46 is attached and fixed to the attachment portion 47 of the holder 43.

According to this embodiment having such a structure, the earth plate 46 is attached to the holder 43 made of an insulating material for holding the earth inductor 37 of the noise filter 40, and the winding 39 of the earth inductor 37 is attached to the earth plate 46. Screw hole 46c for connecting one terminal 39c of one and screwing the connection terminal 50 of the external ground wire 20 to the ground plate 46.
Since the external ground wire 20 is connected to the ground terminal 18, it is only necessary to screw the external ground wire 20 into the screw hole 46c of the ground plate 46 with the screw 51. In this case, since the work of tightening the screw 51 is only performed with an ordinary screwdriver, the connection work can be easily performed. In addition, since the ground plate 46 is simply provided with the screw hole 46c, the conventional configuration requiring the long screw 5 (see FIG. 11).
The manufacturing cost can be reduced as compared with.

Further, in the above structure, the ground plate 46 is held by the recesses 47a, 47b and the claws 47c, 47d of the holder 43, so that the ground plate 46 is moved in the direction orthogonal to the plate surface of the ground plate 46. Regulate and
By tightening the screw 48 in the screw hole 46d of the ground plate 46, one terminal 39c of the winding 39 of the ground inductor 37 is connected to the ground plate 46, and further, the screw 48
Is fitted into the fitting hole 49a of the holder 43,
The ground plate 46 is configured to be restricted from moving in the direction along the plate surface of the ground plate 46, whereby the ground plate 46 is attached to the holder 43. In this case, the ground plate 46 is attached to the holder 4
Winding 3 of earth inductor 37
Since the screw 48 for screwing the one terminal 39c of 9 to the ground plate 46 is also used for connection and mounting, the connection and mounting structure can be simplified and the connection and mounting work can be easily performed. become able to.

FIG. 9 shows a second embodiment of the present invention, and the difference from the first embodiment will be described. In the second embodiment, as shown in FIG. 9, the other end 39b of the winding 39 of the earth inductor 37 is caulked and fixed to the caulked portion 54 provided at the lower end 46b of the earth plate 46. Connected. The other configuration is the same as the configuration of the first embodiment. Therefore, also in the second embodiment, it is possible to obtain substantially the same operational effects as in the first embodiment.

FIG. 10 shows a third embodiment of the present invention, and the difference from the first embodiment will be described. In the third embodiment, as shown in FIG. 10, the other end 39b of the winding 39 of the ground inductor 37 is connected to the ground plate 4 by connecting the other end 39b.
6 is connected to the lower end portion 46b of 6 by soldering. The other configuration is the same as the configuration of the first embodiment. Therefore, also in the third embodiment, it is possible to obtain substantially the same operational effects as in the first embodiment.

The present application is not limited to the above embodiment, and for example, by making the fitting holes 49a and 52a slightly larger than the outer diameters of the screws 48 and 51, respectively,
Various modifications are possible, such as a fit having a margin.

[0033]

As is apparent from the above description, the present invention attaches a holding member made of an insulating material for holding the inductance element of the earth inductor type noise filter to the outer wall portion of the range main body, and Since an earth plate that connects one terminal of the winding of the inductance element is attached and a screw hole for screwing the connection terminal of the external earth wire is provided in this earth plate, connect the external earth wire to the earth terminal. This has an excellent effect that the work to be performed can be easily performed and the manufacturing cost can be reduced.

Further, in the above structure, the holding member is provided so as to sandwich the earth plate, and the restricting portion for restricting the movement of the earth plate in the direction orthogonal to the plate surface of the earth plate and the screw provided on the earth plate are provided. Hole, a screw that is screwed into this screw hole and that connects one terminal of the winding of the inductance element to the ground plate by screwing, and a screw that is provided to insert the screw into the holding member. A regulation hole for regulating the movement of the ground plate in the direction along the plate surface is provided, and the ground plate is attached to the holding member by these. As a result, when attaching the ground plate to the holding member, a screw for screwing one terminal of the winding of the inductance element to the ground plate can be used for both connection and attachment. Therefore, the connection and the attachment structure can be simplified and connected. Also, the mounting work can be facilitated.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view around a ground terminal showing a first embodiment of the present invention.

FIG. 2 is a perspective view of the entire microwave oven.

[Figure 3] Side view of the area around the ground terminal

FIG. 4 is a top view of the holder.

[Figure 5] Rear view of the holder

[Figure 6] Rear view of the ground plate

FIG. 7 is a vertical sectional side view showing a state in which the ground plate is being attached to the holder.

FIG. 8 is an electric circuit diagram.

FIG. 9 is a rear view of a ground plate showing a second embodiment of the present invention.

FIG. 10 is a rear view of a ground plate showing a third embodiment of the present invention.

FIG. 11 is a vertical cross-sectional side view around the ground terminal showing the conventional configuration.

[Explanation of symbols]

11 is a range body, 12 is a cabinet, 13 is a rear plate,
14 is a door, 15 is a magnetron, 18 is a ground terminal, 1
9 is a ground rod (external ground), 20 is an external ground wire, 3
4 is a first capacitor, 35 is a second capacitor, 36
Is a third capacitor, 37 is an earth inductor (inductance element), 38 is a core, 39 is a winding, 39c is a terminal, 40 is a noise filter, 41 is a control circuit, 43 is a holder (holding member), and 44 is a substrate part. , 45 is a holding portion, 46
Is a ground plate, 46c is a screw hole, 47a and 47b are concave portions (regulating portions), 47c and 47d are claw portions (regulating portions), 49a.
Is a fitting hole (regulating hole), 50 is a connection terminal, and 51 is a screw.

Claims (2)

[Claims] 1. A microwave oven provided with a ground inductor type noise filter, comprising: a holding member made of an insulating material, which is attached to an outer wall of a range main body and holds an inductance element forming a part of the noise filter. A ground plate attached to the holding member and connected to one terminal of the winding of the inductance element, and a screw hole provided on the ground plate for screwing the connection terminal of the external ground wire A microwave oven characterized by that. 2. A structure for attaching a ground plate to a holding member is provided so as to sandwich the ground plate on the holding member, and regulates movement of the ground plate in a direction orthogonal to a plate surface of the ground plate. A restricting portion, a screw hole provided in the ground plate, a screw that is screwed into the screw hole, and that connects one terminal of the winding of the inductance element to the ground plate by screwing, The holding member is provided so as to insert the screw, and is configured by a restriction hole that restricts movement of the ground plate in a direction along a plate surface of the ground plate. microwave.