JPS59132638A - Holder for switching element - Google Patents

Abstract

PURPOSE:To fix conductive shield plates with a metal radiation fin, to reduce the number of the conductive shield plates, to reduce cost and to save labor of work of a holder for a switching element by a method wherein the switching element and the metal radiation fin are insulated electrically from each other, and the conductive shield plates are equipped to the metal radiation fin to cover the circumference of the switching element. CONSTITUTION:A metal radiation fin 2 equipped with a switching element 1, and the switching element 1 are insulated from each other with an insulating sheet 3, and the whole circumference of the switching element 1 is surrounded with conductive shield plates 4, 5 fixed to the metal radiation fin 2 together with the metal radiation fin 2. Because the switching element 1 and the metal radiation fin 2 are insulated electrically from each other, radiant noise generated at switching time is generated only from the switching element 1. However, the circumference of the radiant noise therof is surrounded with the metal radiation fin 2 and the conductive shield plates 4, 5 having together the same electric potential, and noise is reduced when it comes outside.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a holding device for a switching element used in an induction heating cooker or the like.

Conventional Structure and Problems Conventionally, a semiconductor switching element (hereinafter referred to as a "switching element") of an induction heating cooker has a switching element 1 in order to dissipate heat loss, as shown in Fig. 1. It was necessary to provide large metal heat radiation fins 2. However,
Since the outer case of the switching element 1 and the high voltage part of the switching element 1 are at the same potential, the metal heat radiation fin 2 directly attached to the outer case of the switching element 1 is also at the same potential.
The radiation noise generated by the switching element 1 during switching is also radiated from the metal radiation fins 2, and in order to prevent the radiation noise, a metal shield plate is provided outside the radiation fins, further surrounding the metal radiation fins 2.

Purpose of the Invention The purpose of the present invention is to reduce the number of conductive shield plates as much as possible by fixing the conductive shield plates that suppress radiation noise emitted from switching elements with metal heat radiation fins, thereby reducing costs and labor. do.

Structure of the Invention The present invention electrically insulates a switching element and a metal heat radiation fin of the switching element, and attaches a conductive shield plate to the metal radiation fin to cover the surroundings of the switching element, and the noise source is isolated from the switching element. Only elements,
A metal radiation fin is used as a part of the shield plate.

Description of examples An embodiment of the present invention will be described with reference to FIG.

1 is a switching element, 2 is a metal radiation fin to which the switching element 1 is attached, 3 is an insulating sheet that insulates between the switching element 1 and the metal radiation fin 2, and 4.5 is a conductive shield plate attached to the metal radiation fin 2. , surrounds the entire periphery of the switching element 1 together with the metal heat radiation fins 2 .

Since the switching element 1 and the metal heat radiation fin 2 are electrically insulated, the radiation noise generated during switching is generated only from the switching element 1. However, the radiated noise is surrounded by the metal radiation fins 2 and the conductive shield plates 4 and 5, which have the same electrical potential, and when it goes outside, the noise is reduced. The switching element 1 thus constructed is assembled into a circuit as shown in FIG. That is, in this circuit, a switch 10 is connected to an AC power supply 9, the AC is full-wave rectified by a rectifier bridge 12, the voltage is stabilized by a noise prevention choke coil 14 and a power supply stabilization capacitor 15, and a heating coil 16 and An inverter circuit composed of a resonance capacitor 17 and a switching element 1 is connected to a power supply circuit 19 and an oscillation control circuit 20 for the switching element 1. One end of a capacitor 18 is connected to the metal radiation fin 2 to which the switching element 1 is attached, and the other end of the capacitor 18 is connected to a power line. In this circuit configuration, an alternating current short circuit occurs, and the noise absorbed by the metal radiation fins 2 escapes to the power supply with a stable potential, and the noise radiated from the switching element 1 is attenuated. Furthermore, a hole 21 such as a small slit or circular hole is inserted into the conductive shield plate 4.5 attached to the metal heat radiation fin 2, as shown in FIG.
Leaving the gap open is effective in improving the heat dissipation effect of the switching element 1 and reducing noise.

Moreover, even with the shape of the metal heat dissipation fin 6 shown in FIG.
The operation is exactly the same as in the case shown in the figure.

Further, in the case of the shape of the metal radiation fin 8 shown in FIG. 6, the conductive shield plate 7 has a box shape, but in this case as well, it performs exactly the same function as in the case of FIG. 2.

Effects of the Invention As described above, in the switching element holding device of the present invention, the conventional heat dissipation fins serve as a heat dissipation and noise shield plate, so the conventional noise shield plate is unnecessary and the workability is improved. , there will be a significant improvement in cost, and the effect will be extremely large0

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional switching element holding device, Fig. 2 is a sectional view of an embodiment of the device of the present invention, Fig. 3 is a circuit diagram of the same, and Fig. 4 is a conductive shield used in the device. FIG. 5 is a perspective view showing an embodiment of the plate, and FIGS. 5 and 6 are sectional views showing other embodiments of the present invention, respectively. 1 Switching element, 2, 8.6 Radiation fin, 4, 5.7 Conductive shield plate. Name of agent: Patent attorney Toshio Nakao (1st person)
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Claims (3)

[Claims] (1) A switching device in which a semiconductor switching element is attached to a metal heat radiation fin, the switching element and the metal heat radiation fin are electrically insulated, and a conductive shield plate is attached to the metal radiation fin to cover the semiconductor switching element. Element holding device. (2) The switching element holding device according to claim 1, wherein the metal heat radiation fin is connected to a power supply line via a capacitor. (3) The switching element holding device according to claim 1, wherein the conductive shield plate has holes for heat radiation.