JPH0144967Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a damper drive device for a hot air circulation type microwave oven.

<Prior art> When performing microwave heating in a hot air circulation type microwave oven, a predetermined amount of cooling air is supplied to the heating chamber, and in the case of heater heating in which hot air is circulated by heater heating, the thermal efficiency of the heating chamber is increased. Therefore, the damper is opened and closed to block the cooling air, and a damper drive device using a shape memory alloy spring as the damper spring for driving the damper has been proposed.

By the way, the shape memory alloy spring also moves each time the damper rotates, so if you fix the terminal fixed to the end of the shape memory alloy, the shape memory alloy will move along the trajectory of the damper lid that rotates as the damper opens and closes. Because the trajectories of the springs do not match, there has been a problem in that the biasing force generated when the shape memory alloy spring returns to its original memorized shape when it becomes hot is not sufficiently transmitted to the damper lid.

<Purpose> The present invention has been made in view of the above points, and its purpose is to provide a damper drive device that smoothly transmits the biasing force of the shape memory alloy spring to the damper lid and has stable operation. do.

<Structure> In order to achieve the above-mentioned object, the present invention provides an introduction hole on the wall surface of the heating chamber for introducing cooling air from a cooling fan for cooling electrical components into the heating chamber. A damper assembly covering the entire area is installed in the heating chamber, a damper lid is provided for opening and closing the opening of the damper assembly through which the cooling air is introduced, and one end of a shape memory alloy spring for opening and closing the damper lid is provided. fixing by caulking one terminal and fixing the other end by caulking the other terminal, and rotatably attaching the one terminal to the damper assembly with the one terminal sandwiched between insulating spacers;
The other terminal is sandwiched between insulating spacers and rotatably attached to the damper lid, and is further provided with an energizing section that energizes the shape memory alloy spring to drive the spring.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

1 and 2 are a schematic side sectional view and a schematic cross-sectional view of a hot air circulation microwave oven showing an embodiment of the present invention, and FIG. 3 is a damper as seen from the direction of arrow A in FIG. 1. FIG. 4 is an exploded view of the main parts of the damper, and FIG. 5 is a cross-sectional view of the terminal attachment of the shape memory alloy spring.

In the figure, reference numeral 1 denotes a hot air circulation type microwave oven consisting of a hot air circulation fan 4 disposed on the back side 3 of the heating chamber 2 and a heater 5 attached around the fan 4, and 6 denotes the heating chamber 2. 7 is a control panel on which keys for various operations are arranged. 8 is magnetron 9 and high voltage transformer 1
This is a cooling fan that cools electrical components such as 0. 1
Reference numeral 1 denotes an air introduction hole having a large number of small holes formed in the side wall surface 2' of the heating chamber 2, and a damper assembly 12 that covers the entire area of the air introduction hole 11 is connected to the heating chamber 2 by a damper mounting screw 13. is fixed. The external shape of the damper assembly 12 is a substantially triangular prism with three sides a, b, and c and a height h.
Rotating around the damper shaft 15, the opening 14 is opened in the rectangular opening 14 with side a and height h,
A blocking damper lid 16 is attached, and the protruding piece 1 of the damper lid 16 is attached to the damper shaft 15.
A bias spring 19 is attached between the damper assembly 7 and the protruding piece 18 of the damper assembly 12, as shown in FIG. Reference numeral 20 denotes an L-shaped angle fixed to the damper lid 16, and a step held between insulating spacers 23 and 24 so that the terminal 22 fixing one end of the shape memory alloy spring 21 can rotate freely. A screw hole (not shown) into which the attached screw 25 is screwed is provided. 26 is the damper assembly main body 1
The stepped screw 25, which is held between the insulating spacers 24 and 28, is screwed in so that the terminal 27, which fixes the other end of the shape memory alloy spring 21, can rotate freely. A screw hole (not shown) is provided for attachment. 28' is the terminal 27 of the shape memory alloy spring 21 and the insulating spacer 28.
This is a rib protruding from the insulating spacer 28, which is formed so as to rotate at the same time. The above terminals 22, 2
7 is caulked to electrically and mechanically fix the shape memory alloy spring 21 described above,
A lead wire 29 and a ground wire 30 are connected between both terminals 22 and 27 for supplying power of about 3 V, 3 A AC, and the ground wire 30 is connected to a ground terminal 31 attached to the damper assembly main body 12. ing. Reference numeral 32 designates a resin-molded first duct disposed around the outer periphery of the damper assembly 12, and a resin-molded second duct 33 that integrally holds and fixes the cooling fan 8 and cooling fan motor 8'. and the rear plate 1' of the hot air circulation type microwave oven 1. Reference numeral 34 denotes a ventilation path formed by the first duct 32 and the second duct 33, and the air passing through this ventilation path 34 is discharged from the exhaust louver 35 formed at the upper part of the rear plate 1' into the room. Expelled inside. Although not shown, the lead wire 29 and the ground wire 30 are connected to the secondary winding side of the cooling fan motor 8'.

Next, the operation of the hot air circulation type microwave oven of the present invention having the above configuration will be explained.

First, when performing microwave heating, the magnetron 9, high voltage transformer 10, etc. are activated to irradiate the heating chamber 2 with microwaves, and the cooling fan 8
rotates, and the intake louver 3 formed around the high voltage transformer 10 as shown by arrow B in FIG.
6, the cooling air sucked through the ventilation path 34
The air is discharged indoors through the exhaust louver 35.

On the other hand, during microwave heating, the lead wire 30 is not connected to the secondary winding (not shown) of the cooling fan motor 8', so the current to the shape memory alloy spring 21 is stopped. ing.

Therefore, since the shape memory alloy spring 21 is not in a high temperature state, no biasing force is generated as a spring, and therefore, due to the elastic force of the bias spring 19,
The damper lid 16 is held in the direction ○a that opens the opening 14. Therefore, the cooling air that has passed through the opening 14 enters the heating chamber 2 through the air introduction hole 10, and serves to discharge gaseous components such as steam and gas generated from the food being heated to the indoor side.

Next, when heating the heater by stopping power to the magnetron and starting power to the heater,
Power of approximately 3V, 3A AC is supplied to the shape memory alloy spring 21 from a lead wire 29 and a ground wire 30 connected in parallel to the secondary winding (not shown) of the cooling fan motor 8'. Therefore, the shape memory alloy spring generates heat, reaches a predetermined temperature within a short time, and quickly returns to its original shape with a biasing force in the high temperature state.
The damper lid 16 is rotated about the damper shaft 15 in the closing direction against the elastic force of the bias spring 19. Therefore, since the opening 14 is blocked, no cooling air is supplied into the heating chamber 2, so that the heating chamber is not cooled. especially,
It is possible to efficiently raise the temperature immediately after the start of hot air circulation heating cooking in which heat from a heater is forcibly circulated within a heating chamber. When the damper lid 16 opens and closes, the terminal 22 that fixes one end of the shape memory alloy spring 21 moves in conjunction with the rotation angle of the damper lid 16, as shown in FIG. The shape memory alloy spring 21 operates extremely smoothly because it is sandwiched between the insulating spacers 23 and 24 and rotatably attached by the stepped screw 25.
There is no problem of weakening the biasing force of the shape memory alloy spring 21 that occurs when the temperature rises by applying unnecessary force to the shape memory alloy spring 21. Furthermore, since the terminal 27 that fixes the other end of the shape memory alloy spring 21 is held by a rib 28' formed on the insulating spacer 28, when the terminal 27 rotates, the insulating spacer 28 moves simultaneously. There is no danger that the alternating current power supplied via the lead wire 29 will be short-circuited to ground by contacting the damper assembly body 12.

By the way, when the shape memory alloy spring 21 is directly energized and raised to a predetermined temperature, it maintains the memorized original state and functions as a spring, but even when the energization is stopped, other electrical equipment The heat generated from the parts may cause the damper lid 16 to return to its original shape a little, causing the damper lid 16 to rotate during microwave heating, reducing the opening area.
Since the damper assembly 12 consisting of the damper lid 16 and the shape memory alloy spring 21 is installed in the ventilation path 34 surrounded by the first duct 32 and the second duct 33, the damper lid 16 must be opened at all times. During microwave heating, the cooling air always hits the shape memory alloy spring 21 in the same state, so it has the effect of keeping the shape memory alloy spring 21 at a relatively low temperature.

Therefore, the temperature of the shape memory alloy spring 21 does not rise during microwave heating, and a stable state can be maintained without generating unnecessary biasing force.

<Effects> As explained above, in the present invention, both ends of the shape memory alloy spring are crimped to fix them to the terminals, and the respective terminals are sandwiched between insulating spacers so as to be rotatable in the damper assembly or the damper assembly. Since it is attached to the damper lid, both ends of the shape memory alloy spring that biases the damper lid rotate with the movement of the damper lid, making it possible to efficiently transmit the elastic force of the shape memory alloy spring to the damper lid. ,
It has a stable operation as a damper drive device, and is highly reliable and has high practical value.

[Brief explanation of the drawing]

1 and 2 are a schematic side sectional view and a schematic cross-sectional view of a hot air circulation microwave oven showing an embodiment of the present invention, and FIG. 3 is a damper as seen from the direction of arrow A in FIG. 1. FIG. 4 is an exploded view of the main parts of the damper, and FIG. 5 is a cross-sectional view of the terminal attachment of the shape memory alloy spring. 1... Hot air circulation type microwave oven, 2... Heating chamber, 3... Cooling fan, 12... Damper assembly,
14...Aperture, 19...Bias spring, 16...
Damper lid, 21...Shape memory alloy spring, 24,
27... Insulating spacer, 28... Rib, 29...
Lead wire, 30...ground wire, 31...ground terminal.

Claims (1)

[Scope of utility model registration request] An introduction hole is provided on the wall of the heating chamber to introduce cooling air from a cooling fan for cooling electrical components into the heating chamber, and a damper assembly that covers the entire area of the introduction hole is installed in the heating chamber. , a damper lid for opening and closing the opening for introducing the cooling air of the damper assembly is provided, one end of a shape memory alloy spring for opening and closing the damper lid is fixed by caulking to one terminal, and the other end is fixed to the other terminal. It is fixed by caulking to the terminal, one terminal is sandwiched between insulating spacers and rotatably attached to the damper assembly, and the other terminal is sandwiched between insulating spacers and rotatably attached to the damper lid. 1. A damper drive device for a microwave oven, characterized in that a current-carrying part is installed to drive the shape-memory alloy spring by energizing it.