JP2000314531A - Heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating cooker, in which an opening and closing door for opening and closing the door of a cooking chamber by pivoting the same, is constituted of a simple structure. SOLUTION: In a heating cooker, whose upper wall outer surface is formed of an arced surface and whose cooking chamber opening is opened and closed by an opening and closing door, the opening and closing door 50 is formed of a front lid 51, a rear lid 52 provided with a connecting piece 52e having a connecting unit 52h, side plates 53 provided with an engaging piece 53b having a unit 53e to be connected, and a window plate 54, while the window plate 54 is interposed between the front lid 51 and the rear lid 52, the engaging piece 53b of the side plate 53 is engaged, while being made to oppose respective engaging holes 51d, 52d formed on the side plate 51a of the front lid 51 and the side rim wall 52b of the rear lid 52, and then the unit to be connected 53e of the engaging plate 53b is connected to the connecting unit 52h of the connecting piece 52e with a screw 55 (connecting joining).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooking device for heating an object to be cooked.

[0002]

2. Description of the Related Art Conventionally, a heating cooker for cooking by heating an object to be cooked has been widely used as, for example, an oven toaster.

[0003] In these heating cookers, generally not shown, a cooking chamber is provided inside a housing, heating heaters are arranged above and below the cooking chamber, and the heating chamber is provided on a front surface of the housing. An opening for taking in and out of the cooked food or the cooked food is formed in the cooking chamber, and a grill is disposed between the heating heaters in the cooking chamber. The opening and closing door that opens and closes the opening is configured to move forward and backward from the opening in conjunction with opening and closing of the opening and closing door.

[0004] When cooking, the door is opened, and an object to be cooked is placed on a grill which protrudes forward from the opening in conjunction with the operation of opening the door, and then the door is opened. When closed, the control switch button is operated to supply electric power corresponding to the object to be cooked to the heating heater to perform heating cooking, and when cooking is completed, the openable door is opened to take out the food.

[0005] As described above, in the prior art in which a part of the grill is moved in and out of the opening in conjunction with the opening / closing operation of the opening / closing door, it is easy to take in / out an object to be cooked. When the opening and closing door is opened and closed, a part of the grille projecting from the opening overlaps with the opening and closing door. There is a problem that it falls on the back surface (surface on the cooking chamber side) of the opening / closing door and a part thereof adheres and becomes dirty.

[0006] Further, when the door is opened and closed, since it projects to the front of the housing, a space for opening and closing the door is required on the front, so that a large space is required for cooking. There's a problem.

There is also a configuration in which the upper end, not the lower end, of the opening is opened and closed with the pivot, and a part of the grill is projected from the opening in conjunction with the opening and closing operation of the opening and closing door. However, in the case of such a configuration, a large space is required for cooking, similarly to the above, and debris such as a portion to be cooked placed on a grill is a table on which a heating cooker is placed. Because it falls directly on the
There is a problem that the table and the like must be cleaned after use since the table and the like are soiled.

For the purpose of solving such a problem, the applicant has developed a heating cooker as shown in FIG. 5 and has already filed an application.

[0009] As shown in FIG.
An upper wall outer surface of the casing 101 is formed in an arc surface 102, and a cooking chamber having an opening (not shown) in a front portion is formed therein.
A heating heater (not shown) and a grill (not shown) are provided in the cooking chamber, and the opening (not shown) is opened and closed by the opening and closing door 103. By configuring a grill (not shown) so as not to protrude from the opening, the opening / closing door 10
Since the space for opening and closing 3 is unnecessary, and the debris such as food can be prevented from dropping on the back surface of the opening / closing door 103 or on the table, the drawbacks of the conventional heating cooker are eliminated. Is what it is.

[0010]

The heating cooker developed by the applicant can solve the conventional problems as described above, but has the following problems in manufacturing the open / close door 103. It turned out that it was not always satisfactory in point.

That is, the opening and closing door 103 comprises an outer lid 105 formed in an arc surface as shown in the figure, and side plates 106 formed integrally on both sides of the outer lid 105. Although not shown in FIG. 5, the side plate 106 is configured to be integrally attached to a back cover attached to the back surface of the outer cover 105 by screws.

One method of integrating the side plate 106 and the back cover (not shown) is to form the side plate 106 and the back cover integrally with synthetic resin or sheet metal. Another method is as follows. In this method, the side plate 106 is formed of sheet metal, attached to a back cover, and the back cover to which the side plate 106 is attached is attached to the outer cover 105.

However, when the former side plate 106 and the back cover are integrally formed of synthetic resin, a large molding machine is required, and since heat-resistant resin must be used, the cost is expensive. There is a problem that
Further, when integrally formed by sheet metal processing, a large molding machine, that is, a press machine is required, and similarly, there is a problem that the cost is high.

When the latter side plate 106 is formed of sheet metal and is attached to the back cover, the side plate 106
Must be attached to the outer lid 105 after attaching to the outer lid 105, which causes a problem that the mounting structure is complicated and the mounting operation is complicated.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a housing in which an outer wall of an upper wall is formed in an arc shape and a cooking chamber having an opening at a front portion is formed. In a heating cooker provided with a heating heater provided, a grille provided in the cooking chamber, and an opening / closing door rotatably supported on both side walls of the housing to open and close the opening, The opening / closing door includes a front wall having a front inner surface concentric with the arc surface of the upper wall outer surface and side walls formed at both ends of the front wall, and a square window hole is formed in the front wall. A front lid having a fitting hole formed in each of the side walls, a facing wall facing an inner surface of a front wall of the front lid, and side edge walls corresponding to both side walls of the front lid at both ends of the facing wall. And forming a window hole in the facing wall opposite to the window hole formed in the front lid. A back cover that forms a fitting hole corresponding to a fitting hole formed on both side walls of the front cover on the both side edge walls and forms a coupling piece formed with a connecting portion; and the back cover and the front cover. A transparent window plate that is disposed between and attached to the window frame, and a window plate is interposed between the facing wall of the back cover and the front wall of the front cover, and the side edge walls facing each other. And a side plate formed with a fitting piece having a fitting portion fitted to each fitting hole formed in the side wall and coupled to the coupling portion by coupling means.

As described above, according to the present invention, the front cover, the back cover, the side plate, and the window plate which constitute the opening / closing door for opening and closing the opening of the cooking chamber are separately formed, and the window plate is interposed between the front cover and the rear cover. With the back cover arranged on the back side of the front cover, insert the fitting pieces of the side plate into the fitting holes formed in the side walls of the front cover and the side edge walls of the back cover facing each other, Since the opening and closing door is constituted by joining the joining portion of the fitting piece and the joined portion of the joining piece by joining means, a large molding machine is required even when the side plate is formed of synthetic resin. It is not necessary, and the side plate is not exposed to high temperature, so it is not necessary to use a heat-resistant resin, so it can be inexpensive, and even if it is formed by sheet metal processing, it is necessary to use a large press machine. It can be inexpensive without cost.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.

FIGS. 1 and 2 are perspective views of a cooking device 1 (hereinafter simply referred to as a cooking device). FIG. 1 shows an opening 17 of a cooking chamber 30 through which an object to be cooked or a food is put in and out of the cooking chamber.
FIG. 2 is a view showing a state in which is closed by an opening / closing door 50, and FIG.

In FIG. 1, reference numeral 10 denotes a casing of the cooking device 1. The casing 10 has a ceiling wall 11 as an upper wall having a semi-cylindrical shape, that is, an arcuate surface, and left and right sides provided on both left and right sides of the ceiling wall 11. , A front wall 14 which is continuous with the ceiling wall 11 and is formed on the lower front side, a rear wall 15 which is provided on the rear lower side and is continuous with the ceiling wall 11, and a bottom wall 16. A cooking chamber 30 is formed inside.

As shown in FIG. 2, the front side of the ceiling wall 11 and the left and right side walls 12, 13 is defined by a horizontal plane parallel to a horizontal plane passing through the center of the arc of the ceiling wall 11, and a vertical plane passing through the center. An opening 17 formed by cutting in a parallel vertical plane is provided. That is, the ceiling wall 11 and the left and right side walls 1 are projected from above and from the front by cutting off the projections from the side wall direction into substantially fan-shaped portions of the ceiling wall 11 and the left and right side walls 12 and 13 of the arc-shaped wall.
Opening edges formed by 2 and 13 form the U-shaped opening 17, respectively.

The opening 17 is horizontal and has an opening edge in a U-shape.
The front opening 19 is formed by a vertical opening orthogonal to the upward opening 18 and a forward opening 19 having a U-shaped opening edge and opening forward. An opening area of the opening 17 which is open on the front side of the housing 10, that is, the upward opening 1
The opening area occupied by 8 and the forward opening 19 is the front opening,
An opening region formed by the side openings, that is, the fan-shaped openings 12a and 13a formed by cutting the left and right side walls into a fan shape forms a side opening.

In this embodiment, the upward opening 18 and the forward opening 19 are perpendicular to each other. However, this is not always necessary.

Also, as shown in FIG.
The front edge of the opening edge 18a is provided with an edge frame 18b having a rectangular cross section protruding upward from the opening edge 18a. It functions to abut on the front end of the net 60 to restrict forward movement.

As shown in FIG. 2, a rear reflector 31, right and left reflectors, ie, a left reflector 32 and a right reflector 33, and a front reflector (not shown) are arranged inside the casing 10, as shown in FIG. The rear reflector 31 and the left and right reflectors 3
2, 33, the cooking chamber 30 is surrounded by a front reflector (not shown) and the bottom wall 16.

A step 31a is formed at a substantially middle portion of the rear reflector 31 in the vertical direction, that is, at the same height position as the opening edge 18a of the upward opening 18, and the step 31a is located behind the grill 60. The end 64 is supported.
In addition, the grill 60 has its rear end 64 at the rear reflector 31.
The rearward movement is restricted by contacting the rear portion of the step portion 31a.

The front edge of the front reflector (not shown) is bent so as to cover the upper surface of the front edge of the opening edge 18 a of the upward opening 18. The support surface (not shown) supports the front part.

That is, the grill 60 is formed at the front end (not shown).
On the support surface (not shown), and the rear end portion 64 with the step portion 31.
a and the front end and the rear end are
8b abuts on the inner surface and the rear part of the rear reflector 31 to restrict the movement in the front-rear direction. The left end 65 and the right end (not shown) contact the left reflector 32 and the right reflector 33 and move left and right. Is restricted and the cooking chamber 30 is detachably provided in the cooking chamber 30.

The rear reflector 31 and the front reflector (not shown) have inclined surfaces inclined toward each other as they approach the lower part of the housing 10, that is, the waste storage tray 68 provided at the bottom of the cooking chamber 30. When the debris such as the food placed on the grill 60 falls, the debris is guided into the debris storage tray 68.

The waste storage tray 68 can be put in and taken out of a tray room (not shown) formed in the lower part of the housing 10 through a drawer port 22 provided on the front surface, and is full of waste such as food to be cooked. When it becomes, it is pulled out from the outlet 22 and thrown away at a predetermined place.

The cooking chamber 30 is provided with an upper heater 41 as a heating heater for heating an object to be cooked at an upper part, and a lower heater 42 as a heating heater similarly at a lower part. Are arranged. The upper heater 41 and the lower heater 42 are detachably attached to sockets 44 attached to the left and right side walls 12 and 13 of the housing 10.

As shown in FIG. 1 and FIG.
The right side of the front wall 14 is an operation panel 23, and a control room 24 is formed inside the casing 10 corresponding to the operation panel 23 as shown in the figure. The control room 24 houses a control circuit (not shown) for controlling the amount of power supplied to the upper heater 41 and the lower heater 42 to adjust the amount of heat generated. Terminals (not shown) of the socket 44 are also connected by lead wires (not shown).

The control circuit includes the operation panel 2.
Signals from a timer 26a, a cooking temperature setting switch 26b, and a start switch 26c provided in the apparatus 3 are input.

The upward opening 18 of the front wall 14
A support step 14a for supporting a front edge of the door 50, which will be described later, is formed in the vicinity of the lower part of the opening edge 18a.

As shown in FIGS. 1 and 2, ribs 27 are formed on the left and right side walls 12 and 13 of the housing 10 so as to protrude outward from the wall surfaces. Also, a rib 28 protruding outward from the wall surface is formed.

The amount of protrusion of the ribs 27 and 28 from the left and right side walls 12 and 13 and the rear wall 15, that is, the protrusion dimension, is determined by the front cover 5 of the door 50.
The opening and closing door 50 is set so as to protrude outward by a predetermined distance from the outer surfaces of the first and side plates 53 so as not to interfere with a wall or the like when the opening and closing door 50 is opened and closed.

In FIGS. 1 and 2, reference numeral 70 denotes a support leg attached to the housing 10.

Next, the door 50 for opening and closing the opening 17 will be described. The opening / closing door 50 includes a front cover 51, a back cover 52, a side plate 53, and a window plate 54 as shown in FIG.

The front cover 51 has a rectangular front wall 51a having a front inner surface concentric with the arc surface of the ceiling wall 11, and side walls 51b formed at both ends in the longitudinal direction of the front wall 51 (note that Since the left and right side walls 51b have the same configuration, only one side, that is, only the right side wall is shown in the figure, and the front wall 51a has a rectangular window hole 5b.
1c is formed. Each of the side walls 51b is formed with a slit-shaped fitting hole 51d. A handle 51e is attached to the center of the lower end of the front wall 51a.

The back cover 52 has an opposing wall 52a facing the inner surface of the front wall 51a of the front cover 51, and side edge walls 52b formed at both longitudinal ends of the opposing wall 52a. The outer side surface of the side edge wall 52b comes into contact with the inner surface of both side walls 51b when the opposing wall 52a of the back cover 52 is arranged to face the back side of the front wall 51a of the front cover 51.

The front wall 51a is provided on the facing wall 52a.
The window hole 52c is formed so as to face the window hole 51c formed in the window hole 51c. The size of the window hole 52c is larger than the window hole 51c. In the side edge wall 52b, a fitting hole 52d having the same shape as the slit-shaped fitting hole 51d formed in the side plate 51b of the outer lid 51 is formed.

Further, the opposite wall 52 of the side edge wall 52b is provided.
A pair of connecting pieces 52e formed so as to protrude inward is formed at the edge opposite to the side a, and the connecting piece 52e is substantially intermediate in the longitudinal direction as shown in FIGS. A connecting portion 52f formed by projecting upward is formed in the portion, and an upper surface 52g of the connecting portion 52f is formed in a fitting hole 52d formed in the side edge wall 52 and a side wall 51b of the front cover 51. The formed fitting hole 51d is set to be flush with the lower edge in FIG. Further, a through-hole 52h is formed in the connecting portion 52f.

The distal end of the connecting piece 52e is bent upward in FIG. 4, and a pressing portion 52i is formed at the distal end thereof.
In the free state, as shown by a two-dot chain line, it slightly projects from the window hole 52c. This allows the window plate 54 to be connected to the front wall 5 of the front lid 51 as described later.
1a is urged toward the back surface.

Further, the window hole 5 is formed in the facing wall 52a.
A plurality of projections 52j are formed in the vicinity of the periphery of 2c to abut on the periphery of the window plate 53 for positioning.

Next, as shown in FIG. 3, the side plate 53 has a fan-shaped covering plate 53a for covering the fan-shaped openings 12a and 13a, and a to-be-coupled portion formed by bending the tip of the covering plate 53a at a right angle. And a screw formed in the fitting piece 53b in correspondence with a through hole 52h formed in a connecting portion 52f provided in a connecting piece 52e formed in the back cover 52. A hole 53c is formed.

The region of the coupling piece 52e facing the coupling portion 52f constitutes the coupled portion 53e.

A shaft 53d is formed near the other end of the cover plate 53b. The shaft 53d is rotatable by bearings (not shown) provided on the left and right side walls 12 and 13 of the housing 10. It is supported by.

The window plate 54 is made of transparent heat-resistant glass and is formed in an arc surface along the back surface of the front wall 51a of the front cover 51, and the size thereof is the same as that of the window hole 51c.
The outer edge portion of the window hole 51c is larger than the outer edge portion of the window hole 51c shown by a two-dot chain line in FIG.

The window plate 54 is connected to the opposite wall 5 of the back cover 52.
When placed on 2a, its outer periphery is positioned by the projection 52j.

Next, how to assemble the door 50 will be described.

First, the window plate 54 is positioned and placed on the opposing wall 52a of the back cover 52 by the projection 52j, and the back cover 52 in this state is placed on the back of the front cover 51 from the back of the window hole 51c. Window 52c formed in opposing wall 52a of lid 52
And the fitting hole 52d of the side edge wall 52b of the back cover 52 is matched with the fitting hole 51d of the side wall 51b of the front cover 51.

Next, the fitting piece 53b of the side plate 53 is
1b is inserted into the fitting hole 52d and the fitting hole 51d from the outside direction and fitted. At this time, the screw hole 53c of the fitting piece 53b and the through hole 52h of the coupling piece 52e match as shown in FIG. 4, and in this state, the screw 55 as the coupling means is inserted through the through hole 52h. It is screwed into the screw hole 53c of the coupling piece 52e. As a result, as shown in FIG. 4, the front cover 51 and the back cover 52 are integrally assembled by the fitting pieces 53b of the side plates 53 fitted into the respective fitting holes 51d and 52d, and the window plate 54 is formed. Is disposed between the front cover 51 and the back cover 52.

In the assembled state, as shown in FIG. 4, a pressing portion 52i formed at the distal end of the connecting piece 52e is formed.
Is deformed and immersed in the window hole 52c by the window plate 54, that is, the window plate 54 is pressed against the back surface of the front wall 51a of the front cover 51 by the urging force generated in the coupling piece 52e by being deformed. In addition, it is positioned and attached without moving between the front cover 51 and the back cover 52.

Then, the door 50 thus assembled is assembled.
The shaft 53d provided on the cover plate 53a is
It is mounted on a bearing (not shown) provided on the left and right side walls 12 and 13 so that the opening 17 can be opened and closed by rotating around the bearing.

Next, the operation of the cooking device 1, that is, the operation for cooking will be described.

First, a material for desired cooking, that is, an object to be cooked is prepared. Then, the user grips the handle 51e of the opening / closing door 50 of the cooker 1 with his / her finger and pivots backward until the rear edge of the front cover 51 comes into contact with the ribs 27 and 28 provided on the left and right side walls 12, 13 and the rear wall 15. Then, the opening 17 is opened.
Next, after the prepared object is placed on the grill 60, the opening / closing door 50 is rotated forward to close the opening 17.

The cooking conditions, that is, the cooking time is set by operating the timer 26a, the cooking temperature is set by the cooking temperature setting switch 26b, and the start switch 26c is operated.
When this operation is performed, the control circuit 25 supplies power to the upper heater 41 and the lower heater 42 according to the set cooking conditions. As a result, the object is cooked by heating.

When the cooking is completed, the opening / closing door 50 is rotated backward again to open the opening 17, and then the cooked food is taken out from the cooking chamber 30, and the cooked food is placed on a prepared plate or the like. The transfer operation ends the cooking operation.

When the opening / closing door 50 is opened in order to put articles to be cooked into and out of the grill 60 disposed in the cooking chamber 30, the fan-shaped openings 12a, which are side openings of the opening 17, are provided as described above. The opening 13a is open and does not hinder the wrist portion from hitting the left and right opening edges of the opening 17 at the time of putting in and taking out, so that the operation of putting the object to be cooked into and out of the grill 60 can be facilitated. In addition, the front of the grill 60 corresponding to the upward opening 18 is
In the state where 0 is opened, since it is exposed to the upward opening 18, the operation of taking in and out the object to be cooked into and out of the grill 60, that is, the operation of taking in and out of the cooking chamber 30 is further facilitated.

Further, there is no danger of burns or the like because the wrist does not hit the left and right opening edges of the opening 17 when the object to be cooked is put in and out of the cooking chamber 30.

Even if the cooking device 1 is used so as to be in contact with the corner wall of the kitchen during cooking, the ribs provided on the left and right side walls 12 and 13 and the rear wall 15 of the cooking device 1 can be used. 27 and 28 abut against the wall, and the ribs 27 and 28 protrude from the outer surface of the door 50 by a predetermined dimension, so that a gap of the predetermined dimension is provided between the door 50 and the wall. Since it is formed, the opening / closing door 50 is prevented from interfering with a wall or the like during the opening / closing operation, so that there is no hindrance to the opening / closing operation.

Further, since a gap is formed between the ribs 27 and 28 and a wall or the like, it is possible to prevent the wall or the like from being adversely affected by heat generated from the cooking device 1 during cooking.

As described above, the front cover 51, the back cover 52, the side plate 53, and the window plate 54 constituting the opening / closing door 50 for opening and closing the opening 17 of the cooking chamber 30 of the cooking device 1 are separately formed.
The back cover 52 is arranged on the back side of the front cover 51 with the window plate 54 interposed between the front cover 51 and the fitting hole 51d formed in the side wall 52b of the front cover 51 and the side edge wall 52b of the back cover 52. Fitting hole 5
2d, the fitting piece 53b of the side plate 53 is inserted, and the connecting part 52f of the fitting piece 53b and the connected part 53e of the connecting piece 53b are connected by a screw 55 as a connecting means, thereby opening and closing the door 50. Since the side plate 53 is made of synthetic resin, a large molding machine is not required, and the side walls 12 and 13 do not have the fan-shaped openings 12a and 13a. In this case, the side plate is not exposed to high temperature, so that it is not necessary to use a heat-resistant resin, and it can be made inexpensive. You can do it.

In the above embodiment, the connecting piece 5
Although the pressing portion 52i for pressing the window plate 54 is formed in 2e, it may be provided separately on the back surface side of the side wall 52b or the opposing wall 52a around the window hole 52c.

In the above embodiment, the connecting means is a screw. However, the connecting means may be another means such as welding.

In the above embodiment, the cover plate 53a of the side plate 53 of the opening / closing door 50 is simply formed into a flat plate, but this is because the side wall 51b of the front cover 51 and the side edge wall 52b of the back cover 52 overlap. The combined thickness is increased, and the cover plate 53a and the housing 1
In the case where a large gap is formed between the left and right side walls 12 and 13 of the housing 10, as shown by a two-dot chain line in FIG. Should be brought close to the outer surface.

[0066]

As described above, according to the present invention, a front cover, a back cover, a side plate and a window plate which constitute an opening / closing door for opening and closing an opening of a cooking chamber are separately formed, and a window plate is provided between the front cover and the rear cover. The back cover is arranged on the back side of the front cover with interposition, and the fitting piece of the side plate is inserted into the fitting hole formed on the side wall of the front cover and the fitting hole formed on the side edge wall of the back cover facing each other. Then, since the opening / closing door is constituted by joining the joining portion of the fitting piece and the joined portion of the joining piece by joining means, even when the side plate is formed of synthetic resin, it is large. There is no need for a molding machine, and since the side plates are not exposed to high temperatures, there is no need to use a heat-resistant resin, so it can be made inexpensive. That have the effect of being inexpensive without having to A.

[Brief description of the drawings]

FIG. 1 is a perspective view of a heating cooker according to an embodiment of the present invention (in a state where an opening / closing door is closed).

FIG. 2 is a perspective view of the heating cooker (in a state where an opening / closing door is opened).

FIG. 3 is an exploded perspective view of an opening / closing door of the cooking device.

FIG. 4 is a cross-sectional view showing a mounting state of a front cover, a back cover, a side plate, and a window plate of an opening / closing door of the cooking device.

FIG. 5 is a perspective view of a cooking device already developed by the applicant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating cooker 10 Housing 11 Ceiling wall (upper wall) 17 Opening 30 Cooking room 41 Upper heater (heating heater) 42 Lower heater (heating heater) 50 Opening / closing door 51 Front cover 51a Front wall 51b Side plate 51c Window hole 51d Fitting Hole 52 Back lid 52a Opposing wall 52b Side edge wall 52c Window hole 52d Fitting hole 52e Coupling piece 52f Coupling part 53 Side plate 53b Fitting piece 53e Coupling part 54 Window plate 60 Grill net

Claims (1)

[Claims] 1. A housing having an upper wall having an arcuate outer surface and a cooking chamber having an open front, a heating heater disposed in the cooking chamber, and a baking oven disposed in the cooking chamber. In a heating cooker provided with a net and an opening / closing door rotatably supported on both side walls of the housing to open and close the opening, the opening / closing door has a front inner surface concentric with an arc surface of an upper wall outer surface. A front wall having an arcuate surface and side walls formed at both ends of the front wall, a rectangular window hole is formed in the front wall, and a front lid having a fitting hole formed in each of the both side walls; A facing wall facing the inner surface of the front wall of the front cover, and a side edge wall corresponding to both side walls of the front cover at both ends of the facing wall, and facing the window hole formed in the front cover in the facing wall. And a fitting hole formed on both side walls of the front lid on the both side edge walls. A back cover forming a coupling piece having a fitting portion formed with a fitting hole formed therein; a transparent window plate disposed between the back cover and the front cover and attached to the window frame; A window plate is interposed between the opposing wall of the lid and the front wall of the front lid, and is fitted into respective fitting holes formed in the side edge wall and the side wall facing each other, and is coupled to the coupling portion. And a side plate on which a fitting piece having a portion to be joined is formed.