JPH0332014A - Standard capacitor - Google Patents

Abstract

PURPOSE:To the temperature difference between the inner part and the outer part of an outer case and to prevent the condensation of dew and the formation of rust by providing projections which protrude to the inner side toward an inner case in a radiation. fin pattern on the inner side surface facing the attaching surfaces of lead terminals of the outer case. CONSTITUTION:Projections 32 are provided at the inner side surface facing the attaching surfaces of terminals 16-19 of an outer case 4 of a standard capacitor 31 in a radiation-fin pattern. Lead-out parts from an inner case 3 are sealed with hermetic seals 21. Lead terminals 11 and 12 and 13 and 14 of a capacitor main body 2 which are connected to terminals 16 and 17 and 18 and 19 are coated with silicone resins 33. Therefore, the heat capacity of the attaching parts of the terminals 16-19 of the case 4 becomes large, and the temperature difference between the outer part and the inner part of the case 4 is alleviated. Thus, the condensation of dew and the formation of rust on the inner surface of the outer case are suppressed, and the stable capacitance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a standard capacitor used as a standard for capacitance in manufacturing capacitors, calibrating measuring instruments for measuring capacitance of capacitors, and the like.

[Prior Art] Generally, capacitor manufacturers and capacitor capacitance measuring equipment manufacturers are equipped with standard capacitors that serve as standards for determining the capacitance value of manufactured capacitors and measuring accuracy of manufactured measuring instruments. There is.

The structure of a conventional standard capacitor of this type is shown in FIG.

The standard capacitor 1 is of a sealed type in order to prevent the capacitance from changing due to the influence of humidity.

That is, in the standard capacitor 1, a capacitor body 2 having a standard capacitance is housed inside an inner case 3, and this inner case 3 is further housed inside an outer case 4 made of metal. This outer case 4 is made of a metal material in order to electromagnetically shield the capacitor body 2 housed therein.

From the inner case 3, lead terminals 11 and 12 are electrically connected to the electrodes 5 and 6 of the capacitor body 2, respectively.
and 13.14 are elicited.

And these lead terminals 11, 12 and 13°14
Accordingly, the electrodes 5 and 6 of the capacitor body 2 are connected to terminals 16, 17 and 18, 19, respectively, insulated from the outer case 4 by the insulator 15, and led out to the outside of the outer case 4. Lead terminals 11, 12 and 13 above
．． 14 is a hermetic seal 21 for the inner case 3.
It is sealed by.

The size of the inner case 3 is smaller than the size of the outer case 4, and there is a space 22 between the two.
There is air inside. Since this air exists in the closed space 22 between the inner case 3 and outer case 4, it does not flow, and even if the temperature outside the outer case 4 changes, the temperature of the capacitor body 2 does not change much, and the temperature Changes in capacitance are suppressed.

[Problems to be Solved by the Invention] By the way, the standard capacitor 1 is normally used in a place where the temperature and humidity are controlled to constant values. Therefore, the standard capacitor 1 does not experience sudden temperature changes during its use. However, the standard capacitor 1 is inevitably exposed to temperature changes during storage or movement. In such a case, a temperature difference occurs between the temperature outside the outer case 4 of the standard capacitor 1 and the temperature of the air in the space 22.

In particular, when the temperature outside the outer case 4 suddenly drops, moisture contained in the air in the space 22 may condense on the inner surface of the outer case 4, and this condensation may cause rust inside the outer case 4. do.

For this reason, in the conventional standard capacitor 1 described above, due to dew condensation and rust on the inner surface of the outer case 4, the terminals 16°17 and 18
．． There was a problem in that the insulation state between capacitors 19 and 19 changed, and this caused a change in the capacitance of the standard capacitor l.

An object of the present invention is to provide a standard capacitor that can obtain stable capacitance without causing dew condensation or rust on the inner surface of the outer case.

[Means for Solving the Problems] Therefore, the present invention includes an inner case that houses a capacitor body having a standard capacitance, and an outer case made of metal that houses this inner case. , a standard capacitor comprising a lead terminal connected to an electrode of the capacitor main body drawn out from the inner case and a terminal leading out to the outer surface of the outer case while being electrically insulated from the outer case; The outer case is characterized by having a protrusion that protrudes inward from its inner surface toward the inner case to reduce the temperature gradient between the outside and the inside of the outer case.

[Operations] The outer case has a large heat capacity in the portion where the protrusions are formed. Therefore, if the temperature outside the outer case suddenly changes, this temperature change will quickly spread from the outside to the inside of the outer case.

This suppresses the temperature difference between the outside and inside of the outer case.

[Effects of the Invention] According to the present invention, the temperature gradient between the outside and the inside of the outer case is alleviated by the protruding portion of the outer case, and even if the temperature outside the outer case changes rapidly, this temperature change is quickly suppressed. This extends from the outside of the outer case to the inside, suppressing condensation on the inner surface of the outer case, preventing condensation or rust from forming on the inner surface of the outer case, and ensuring stable capacitance at all times. can.

[Examples] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

An example of a standard capacitor according to the present invention is shown in FIG.

The above-mentioned standard capacitor 31 is obtained by applying the present invention to the standard capacitor l described in FIG. 3, and corresponding parts are indicated by corresponding symbols, and redundant explanation will be omitted.

The above standard capacitor 31 is the standard capacitor 3 in Fig. 3.
A protrusion 32 protrudes inwardly toward the inner case 3 on the inner surface opposite to the mounting surface of the terminals 16 to 19 of the outer case 4 of 1.
are provided in the form of heat dissipation fins.

The drawer part from the inner case 3 is Hermetic Sock Seal 2
1, each of the above terminals 16, 17 and 18
．． The lead terminals 11, 12 and 13, 14 of the capacitor body 2, which are connected to the capacitor 19, are coated with silicone resin 33 or the like.

In this way, the portions of the outer case 4 where the terminals 16 to 19 are attached have a large heat capacity due to the projections 32, and the temperature gradient between the outside and the inside of the outer case 4 is alleviated.

Incidentally, the standard capacitor 31 shown in FIG. 1 is housed in a thermostat (not shown) for environmental testing, and the inside of the inner case 3, the spaces 22 between the inner case 3 and the outer case 4, and the outer case are A thermocouple (not shown) is installed on the outside of each of 4,
The temperature inside the thermostat was lowered from 25°C to 5°C, and the temperature at each of the above positions was measured using a temperature recorder (not shown) connected to the thermocouple, as shown in Figure 2. The results shown are obtained. In this figure 2, the curve h
r is the external temperature of the outer case 4 of the standard capacitor 31; the curved line is the space 22 between the outer case 4 and the inner case 3 of the standard capacitor 31; The temperature of the curve is the temperature inside the inner case 3.

As can be seen from FIG. 2 above, in the vA standard capacitor l shown in FIG. I can see that

In the embodiment shown in FIG. 1, the projections 32 may be provided on the entire inner surface of the outer case 4. In this way, the outer case 4 can be
Rapid temperature changes in the space 22 between the inner case 3 and the inside of the inner case 3 can be suppressed more effectively. Further, the protrusion 32 may be provided to bridge the outer case 4 and the inner case 3.

The present invention can also be applied to standard capacitors having structures other than the standard capacitor 1 having the structure illustrated in FIG.

[Brief explanation of drawings]

Fig. 1 is a structural explanatory diagram of one embodiment of the standard capacitor according to the present invention. Fig. 2 shows the temperature change inside the inner case with respect to the external temperature change of the standard capacitor shown in Fig. 1, and the difference between the inner case and the outer case. FIG. 3 is an explanatory diagram of the structure of a conventional standard capacitor. 2... Capacitor body, 3... Inner case. 4... Outer case, 5, 6... Electrode terminal. 11.12, 13.14...Lead terminals. 15... Insulator, 16.17, 18.19... Terminal. 22...Space, 31...Standard capacitor. 32...Protrusion, 33...Silicone resin. Patent applicant Murata Manufacturing Co., Ltd. Representative Patent attorney Haka Aoyama 1 person Figure 1 Figure 2 □ Time (minutes) Figure 3

Claims (1)

[Claims] (1) An inner case that houses a capacitor body having a standard capacitance, a metal outer case that houses this inner case, and an electrode of the capacitor body pulled out from the inner case. In a standard capacitor comprising a terminal for leading out a lead terminal to be connected to the outer surface of the outer case while being electrically insulated from the outer case, the outer case is arranged inward from the inner surface toward the inner case. A standard capacitor characterized by having protrusions that protrude into the outer case and reduce the temperature gradient between the outside and the inside of the case.