JPS63190286A - Microwave oven - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a microwave oven for cooking food.
In particular, the present invention relates to an inrush current suppressing device that protects a magnetron in a high frequency oscillation circuit by suppressing an inrush current that occurs when the microwave oven starts operating.

(Prior Art) An inrush current suppressing device for a microwave oven of this kind that has already been proposed is configured with an electric circuit as shown in FIG. 4.

That is, in FIG. 4, the power supply circuit 1 includes a main fuse 2.
, a main timer switch 3a, and a power control timer switch (also referred to as ON-OFF timer or vPC) 4a for output control are connected in series.
The main timer 3 of the main timer switch 3a and the power control timer 4 of the power control timer switch 4a are connected in parallel to the power supply circuit 1.

The power supply circuit 1 also includes a primary winding 5 of a high voltage transformer 5.
a is connected, and the secondary winding 5 of this high voltage transformer 5
A high frequency oscillation circuit 6 containing a built-in magnetron is provided on the a side. Further, a parallel circuit 9 of a resistor 7 and an AC relay switch 8a is connected in series to one end of the primary winding 5a of the high voltage transformer 5. are connected to the power supply circuit 1 in four rows.

Therefore, when the above-mentioned inrush current control device for a microwave oven starts cooking, the main timer 3 and the power control timer 4 are energized, and the main timer switch 3a and the power control switch 4a are turned on.
The high voltage transformer 5 and the AC relay 8 are also excited,
The AC relay switch 8a of this AC relay 8 is turned on. Therefore, current flows through the resistor 7 to the high-voltage transformer 5 during the relay operation time from the start of energization until the AC relay switch 4a is turned on, so that the inrush current generated at the start of energization is suppressed. Note that when the AC relay switch 4a is turned on, the current to the resistor 7 is short-circuited.

(Problems to be Solved by the Invention) However, since the relay operating time of the AC relay 8 in the above-described inrush current control device for a microwave oven is an extremely short time of, for example, several milliseconds, the AC
In Relay 8, not only is it difficult to compensate for the normally known required time for inrush current (approximately 10 milliseconds), but also the effect of suppressing inrush current is unstable due to variations in relay operating time due to relay coils. Moreover, since the AC relay 8 is used, it is difficult to provide it at a low cost.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to reliably and stably suppress the inrush current that occurs at the start of energization, and also to simplify the configuration and facilitate assembly. The purpose of the present invention is to provide a microwave oven designed to save labor through mass production.

[Structure of the invention]

(Means and Means for Solving Problems) The present invention includes:
A parallel circuit of a resistor and a suppression switch is connected in series to one end of the primary winding side of a high-voltage transformer that supplies power to the magnetron, and one end of the shape memory alloy material is connected to the parallel circuit near the suppression switch. The other end of the shape memory alloy material is connected to the other end on the primary winding side, and a part of the shape memory alloy material operates the suppression switch when the current is started. It is configured to stably and reliably suppress the inrush current that occurs.

(Example) Hereinafter, the present invention will be described with reference to an illustrated embodiment.

It should be noted that the present invention will be described with the same reference numerals attached to the same constituent members as in the two specific examples.

1 to 3, reference numeral 1 denotes a power supply circuit in a microwave oven, and this power supply circuit 1 includes a main fuse 2, a main timer switch 3a, a power control timer switch (ON- (also referred to as OFF timer or VPC) 4a are connected in series, and the main timer 3 of the main timer switch 3a and the power control timer 4 of the power control timer switch 4a are connected in parallel to the power supply circuit 1. . In addition, this power supply circuit 1 includes one of the high voltage transformers 5.
The next winding 5a is connected to the second winding of this high voltage transformer 5.
A high frequency oscillation circuit 6 including a built-in magnetron is provided on the side of the next winding 5b.

Further, a parallel circuit 9 including a resistor 7 and a suppression switch 10 is connected in series to one end of the primary winding 5a of the high voltage transformer 5, and the parallel circuit 9 in the vicinity of the -1x suppression switch 10 is connected in series to one end of the primary winding 5a of the high voltage transformer 5. 9 includes one end 1 of the shape memory alloy material 11.
1a is connected, and the other end of this shape memory alloy material 11 is connected to the other end on the primary winding 5a side. Furthermore, in the offset position of this shape memory alloy material 11,
A support shaft 12 is mounted on the shape memory alloy material 11. When electricity starts flowing through the shape memory alloy material 11, current also flows through the shape memory alloy material 11, turning the curved shape memory alloy material 11 into a straight shape memory alloy material 11. It is deformed and swings about the support shaft 12 as a fulcrum to turn the suppression switch 10 ONL (
(See Figures 2 and 3).

In particular, the time required for the shape memory alloy material 11 to change (restore) shape and turn on the suppression switch 10 is determined by selection of the material of the shape memory alloy material 11, the current flowing during energization, etc. Note that it is sufficient to set the time required for inrush current suppression to about 1 second.

Therefore, at the start of heating cooking, the main timer 3 and the power control timer 4 are energized, and the main timer switch 3a and the power control timer switch 4a are connected to each other.
When turned ON, current flows through the shape memory alloy material 11 at the same time as the high voltage transformer 5, which generates heat by itself.
The curved shape memory alloy material 11 is deformed into a linear shape, and as a result, it swings about the support shaft 12 to turn on the suppression switch 10.

Therefore, the overflow current is applied to the resistor 7 for the time required from the start of energization until the suppression switch 10 is turned ON.
Since it flows through the high voltage transformer 5 to the high voltage transformer 5, it is sufficiently suppressed and controlled. Note that when the suppression switch 10 is turned on, the current to the resistor 7 is short-circuited.

Next, when the main timer 2 is turned off, the power to the shape memory alloy material 11 is also cut off, so that the shape memory alloy material 11 returns to its original curved state as shown in FIG. ,''-The suppression switch 10 is turned off.

【Effect of the invention〕

As described above, according to the present invention, a parallel circuit of a resistor and a suppression switch is connected in series to one end of the primary winding side of a high-voltage transformer that supplies power to the magnetron, and the One end of the shape memory alloy material is connected to a parallel circuit, and the other end of the shape memory alloy material is connected to the other end on the primary winding side, and when electricity starts, a part of the shape memory alloy material Since it is intended to activate the suppression switch,
Not only can the inrush current that occurs at the start of energization be suppressed effectively and stably, but also because the above-mentioned shape memory alloy material is used, the suppression operation time can be freely set and there is no variation in the operation time. Since the structure is simple, it can be easily assembled and can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of a microwave oven of the present invention, FIG. 2 is a perspective view showing the main parts of the present invention, FIG. 3 is a diagram for explaining the present invention in detail, and FIG. 4 is a diagram for explaining the present invention in detail. , is an electric circuit diagram of a microwave oven that has already been proposed. 1... Power supply circuit, 3... Main timer, 4... Power control timer, 5... High voltage transformer, 6...
...High frequency oscillation circuit, 7...Resistor, 10...Suppression switch, 11...Shape memory alloy material. Applicant's agent Mr. Sato Figure 1 Figure 28 Figure 3 Figure 4

Claims (1)

[Claims] A parallel circuit of a resistor and a suppression switch is connected in series to one end of the primary winding side of a high-voltage transformer that supplies power to the magnetron, and one end of the shape memory alloy material is connected to the parallel circuit near the suppression switch. The other end of the shape memory alloy material is connected to the other end on the side of the primary winding, and when electricity starts, a part of the shape memory alloy material operates the suppression switch. Microwave oven.