JPH03250613A - Feed-through capacitor - Google Patents

Abstract

PURPOSE:To improve a filter efficiency by enlarging an electrode area and increasing the capacitance without changing an interelectrode distance and by obtaining a large capacitance by means of a simple structure through making the shape of the cross section of a high-potential electrode and ground-potential electrode into a petal shape. CONSTITUTION:An internal high-potential electrode 12 is formed into a bottomed cylinder by deep drawing an iron plate through a press and almost into a petal shape in the cross-section and into a corrugated irregularity 12a in the outer peripheral face. Further, an external ground-potential electrode 13 is formed into a cylinder by deep drawing an iron plate through a press and almost into a petal shape in the cross-section and into a corrugated part 13a in the outer peirpheral face. Also, the irregularity 12a of the internal high-potential electrode 12 and that 13a of the external ground-potential electrode 13 coincide with each other in irregularity phase and the gap between the internal high-potential electrode 12 and the external ground potential electrode 13 is kept almost constant over the whole periphery. Thus, when the electrode area of the internal high-potential electrode 12 and external ground-potential electrode 13 is increased, the capacitance becomes larger.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a feedthrough capacitor fixed to a shield box of a magnetron for a microwave oven, for example.

(Prior Art) In a microwave oven magnetron, a negative high voltage and filament cathode heating power are applied from the cathode-containing stem side. In the case of a magnetron used in a household microwave oven, the anode voltage is, for example, 4 kV, the anode current is 30 mA, and the filament voltage is 3.15 V.
, the filament current is 1.0 A.

Conventionally, a feedthrough capacitor using a ceramic high dielectric element has been used as a high voltage terminal that introduces such a high voltage and large current. In this system, a feedthrough capacitor serving as an input terminal has a capacitance of several hundred pF, and together with a choke coil, it forms an LC filter to suppress noise generated in the magtron.

By the way, the withstand voltage of high dielectric elements to which high voltage is applied is particularly important, and the elements are coated with insulating resin to protect the interface, but this has a large impact on the manufacturing process, and quality control of withstand voltage is important. is extremely difficult. For this reason, efforts have been made in recent years to simplify the structure of high-voltage input terminals as much as possible. Therefore, a method of manufacturing an insulating resin by injection molding without using the above-mentioned ceramic high dielectric element has been adopted.

FIG. 4 shows electrode parts constituting a conventional feedthrough capacitor, in which 1 is an input center conductor, 2 is an inner high potential electrode, and 3 is an outer ground potential electrode.

The input center conductor 1 has a main body portion 1a formed by bending a steel plate of a predetermined length into a U-shaped cross section. A flat faston terminal portion 1b is provided at one end of the main body portion 1a, and A through-hole IC is provided at the end. The inner high potential electrode 2 is formed into a cylindrical shape with a bottom by deep drawing an iron plate using a press, and a recess hole 2a into which the input center conductor 1 is inserted is bored at the bottom. The input center conductor 1 and the inner high potential electrode 2 are positioned coaxially, and the recess hole 2a of the inner high potential electrode 2 and the main body portion 1a of the input center conductor 1 are electrically and mechanically coupled by welding. ing. Furthermore, these are tin-plated, and the burrs at the ends of the square electrodes are removed by tampling or the like prior to plating to improve withstand voltage.

The outer ground potential electrode 3 is a cylindrical body with a flange portion 3a formed by deep drawing an iron plate using a press, and the flange portion 3a is provided with three through holes 3b. , nickel plated.

The input center conductor 1, inner high potential electrode 2 and outer ground potential electrode 3 are assembled as shown in FIG. That is, the input center conductor 1 is inserted into the center of the inner high potential electrode 2, and the input center conductor 1 is fixed to the inner high potential electrode 2 by welding with the main body portion 1a inserted into the retraction hole 2a. Then, this inner high potential electrode 2 is set in a mold (not shown), and furthermore, an outer ground potential electrode 3 is fitted on the outside of the inner high potential electrode 2 and held in a coaxially spaced and close state. Then, the insulating resin cylindrical body 4 is molded by injecting heated molten resin into the mold. This insulating resin cylinder 4 has an inner high potential electrode 2 and an outer ground potential electrode 3.
The input center conductor 1
The main body portion 1a is covered by an insulating cylinder 4C.

(Problem to be Solved by the Invention) However, the capacitance of the feedthrough capacitor configured as described above depends on the distance between the inner high potential electrode 2 and the outer ground potential electrode 3, the electrode area, and the dielectric constant of the insulating resin. It is determined by
- For boat fishing, engineering plastics have a dielectric constant of about 3 to 4, so large capacitance cannot be expected, and there were many problems in terms of filter efficiency.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to provide a feedthrough capacitor that is small in size and yet has a large capacitance.

[Structure of the invention]

(Means and Effects for Solving the Problems) In order to achieve the above object, the present invention provides a high-potential electrode made of a metal cylinder that penetrates the inside of the input center conductor and is electrically connected to the input center conductor. A through hole having a ground potential electrode made of a metal cylinder disposed close to and separated from the outside of the high potential electrode, and an insulating resin integrally molded to cover between the two electrodes and the outside of the ground potential electrode. In this type of capacitor, the cross-sectional shapes of the high potential electrode and the ground potential electrode are petal-shaped, and the electrode area is increased without changing the distance between the electrodes, thereby increasing the capacitance.

Claim 2 is an LCP in which the insulating resin contains 70 to 80% by weight of barium titanate powder of high dielectric constant ceramic.
(liquid crystal polymer) and less than 2% by weight of a silane coupling agent.

(Embodiment) Hereinafter, an embodiment of the present invention will be described based on the drawings, and the same components as those in the conventional art will be given the same numbers and the explanation will be omitted.

As shown in FIGS. 1 to 3, the electrode parts constituting the feedthrough capacitor include an input center conductor 11, an inner high potential electrode 1
2. It consists of an outer ground potential electrode 13, and the inner high potential electrode 12 is formed into a cylindrical shape with a bottom by deep drawing an iron plate using a press, and has wavy irregularities on the outer peripheral surface with a cross section or approximately petal shape. It is formed in the portion 12a. Further, the outer ground potential electrode 13 is formed into a cylindrical shape obtained by deep drawing an iron plate by pressing, and has a cross section approximately petal-shaped.
A wavy uneven portion 13a is formed on the outer peripheral surface.

The unevenness phase of the uneven portion 12a of the inner high potential electrode 12 and the uneven portion 13a of the outer ground potential electrode 13 is the same, and the gap between the inner high potential electrode 12 and the outer ground potential electrode 13 is formed on the entire circumference. It remains almost constant throughout. Furthermore, as in the past, an insulating resin cylinder 14 is molded by injecting heated molten resin into a mold, and this insulating resin cylinder 14 is formed between the inner high potential electrode 12 and the outer ground potential electrode 13. is insulated by an insulating layer 14a, the outside of the outer ground potential electrode 13 is insulated by an insulating layer 14b, and the main body portion 11a of the human-powered central conductor 11 is covered by an insulating cylinder 14c. Furthermore, since the insulating cylinder 14C has a tapered shape that tapers toward the tip, it prevents cracks from occurring during mold release.

In this way, the inner high potential electrode 12 and the outer ground potential electrode 13
By increasing the area of the electrodes, the capacitance increases, and with a simple structure, a large capacitance can be obtained and filter efficiency can be improved. Note that the shapes of the uneven portions 12a and 13a are not limited to those in the embodiment described above, and may be petal-shaped consisting of six or more flower moons as long as the uneven phases match.

The insulating resin cylindrical body 14 may be made of an engineering plastic containing 25% by weight or more of glass fiber or Vectra A manufactured by Polyplastics Co., Ltd. as a base polymer.
950, BT made by Fuji Titanium Co., Ltd. to ensure high dielectric constant
70 to 80% by weight of a filler made of 206 BaTi 03 processed to an average particle size of 3 μm, and 2% by weight of a run-coupling agent (TSL8350 manufactured by Toshiba Silicone) to improve the adhesion of the surface of the BaTiO3 powder to the base polymer.
The resin is manufactured by mixing the following ingredients so that they are sufficiently dispersed.

General engineering plastics for injection molding have a dielectric constant of about ε-4 and have little effect in suppressing noise, but the insulating resin of this invention can secure ε-20, so the capacitance of the capacitor can be reduced. At 80pF, a sufficient noise suppression effect can be obtained even when used in a microwave oven magnetron.

Furthermore, a deviation zh of about 1n is provided in the heights of the inner high potential electrode 12 and the outer ground potential electrode 13 that constitute the feedthrough capacitor. Therefore, it is possible to clear the withstand voltage of 15 KV.

〔Effect of the invention〕

As explained above, the first aspect of the present invention is that the cross-sectional shape of the high potential electrode and the ground potential electrode is petal-shaped.
Capacity can be increased by increasing the electrode area without changing the distance between the electrodes.

Therefore, with a simple structure, a large capacity can be obtained and filter efficiency can be improved.

Claim 2 is an LCP containing 70 to 80% by weight of barium titanate powder of high dielectric constant ceramic as the insulating resin.
(Liquid Crystal Polymer) and a silane coupling agent of less than 2% by weight, the capacitor's capacitance is 80 pF, and it is said to have sufficient noise suppression effect even when used in microwave oven magnetrons. effective.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention. Figure 1 is an exploded perspective view of a high potential electrode and a ground potential electrode, Figure 2 is a cross-sectional plan view, and Figure 3 is a through-hole type. FIG. 4 is an exploded perspective view of a conventional feedthrough capacitor, and FIG. 5 is a longitudinal side view of the capacitor. 11... Input center conductor, 12... Inner high potential electrode,
13...Outer ground potential electrode, insulating resin.

Claims (2)

[Claims] (1) A high potential electrode made of a metal cylinder to which the input center conductor penetrates and is electrically connected, and a ground potential electrode made of a metal cylinder placed close to and separated from the outside of this high potential electrode. and an insulating resin integrally molded to cover between the two electrodes and the outside of the ground potential electrode, characterized in that the cross-sectional shape of the high potential electrode and the ground potential electrode is petal-shaped. Feedthrough capacitor. (2) Claim 1, wherein the insulating resin is a resin containing LCP (liquid crystal polymer) containing 70 to 80% by weight of barium titanate powder of high dielectric constant ceramic and less than 2% by weight of a silane coupling agent. Feedthrough capacitor as described in .