JPS5846814B2 - thermal protector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal protector, and particularly to a thermal protector that manually closes the gap between the electrodes after the gap between the electrodes becomes open due to a rise in ambient temperature, that is, a manual return type.

Generally, a thermal protector has a pair of open/close electrodes, consisting of a fixed electrode and a movable electrode equipped with a thermally responsive element such as a bimetal, which becomes open due to an increase in ambient temperature, and current flows to the connected load. It cuts off current and is widely used as a safety device to prevent overheating in various electrical devices.

Conventionally, manual reset type thermal protectors were fixed and
It is known that a resistance element having a positive temperature coefficient is inserted and connected between movable electrodes.

To install this resistance element, insert the resistance element into a recess formed on the movable electrode side, press this resistance element with a plate spring formed on the fixed electrode side, and fix the resistance element between the movable electrodes. This was done by holding it in place.

However, the thermal protector having such a configuration has the drawbacks of low operating temperature reliability and low vibration resistance because the resistive element is simply held between the two electrodes.

An object of the present invention is to obtain a thermal protector that has high reliability in operating temperature and high vibration resistance.

The present invention includes: a block body made of a resistance element having a positive temperature coefficient and having two holes; two conductive sleeves inserted into the holes of the block body and electrically contacting the stiffness block body; an electrical connection between a fixed electrode having a lead inserted into one of the sleeves and electrically contacting the sleeve, and the fixed electrode separated from the fixed electrode when a predetermined set temperature is reached; A thermal protector comprising: a thermally responsive element that opens the thermally responsive element; and a movable electrode that is electrically connected to the thermally responsive element and that is inserted into the other sleeve and has a lead that makes electrical contact with the sleeve. It is characterized by:

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, this thermal 70 protector has an outer diameter of 7.
The container 1 is made of glass and has a length of 5 mm, a length of 33 mm, and a thickness of 0.5 mm, an electrode mount 2 provided inside the container 1, and dry air 3 sealed inside the container 1.

Electrode mount 2 has a wire diameter of 0.7 mm and a total length of 57.5771 mm.
1+! The fixed electrode 4 has a lead with a diameter of 0.7 mm and a total length of 48.5 mm.
Length of protrusion outside the glass tube: 33 m) Glue 5, sub-plate 6, and vertical length welded to this tip: 10 m
a movable electrode 8 having a thermally responsive element 7 made of a plate-shaped bimetal or the like with a lateral length of 5 mm and a thickness of 0.1 mm;
a glass bead 9 for holding both electrodes at a predetermined distance;
A resistance element with a positive temperature coefficient (hereinafter referred to as a positive temperature coefficient thermistor) whose main component is barium titanate, which has a diameter of 5 mm and a thickness of 2.2 mm, and has two holes coated with a silver film that serves as an electrode part on the circumferential surface. ) and a block body 10 which is inserted into the hole of this block body 10 and has an outer diameter of 1.1 mm and a total length of 5 mm (projection length from the block body is 2.8 mm).
, conductive sleeves 11 and 12 made of nickel and having a thickness of 0.1 mm.

A silver contact 13 is provided at the tip of the fixed electrode 4, and a silver alloy contact 14 is provided at the tip of the thermally responsive element 7.

Furthermore, the leads of the fixed electrode 4 and the leads 5 are inserted into the sleeves 11 and 12, respectively.

The container 1 is hermetically sealed at the end 15.

The thermal protector having the above configuration can be obtained by the manufacturing procedure shown in FIGS. 2A to 2F.

Sleeves 11 and 12 shown in FIG. 2A are inserted into holes 10a and 10b of block body 10, respectively.

At this time, the large diameter portions 11a and 12a formed in the sleeves 11 and 12, respectively, are connected to the holes 10a and 10b.
By abutting the edges of the sleeves 11 and 12
are inserted into the holes 10a and 10b of the block body 10 by a predetermined length (FIG. 2C).

Next, as shown in the second diagram, the lead of the fixed electrode 4 welded to the glass bead 9 and one end of the lead 5 are inserted into the sleeves 11 and 12, respectively.
lead and sleeve 11, and lead 5 and sleeve 1
2 are welded (Fig. 2E).

Thereafter, the contact 13 is welded to the tip of the fixed electrode 4, and the sub-plate portion of the thermally responsive element 7, which has the contact 14 welded to one end and the sub-plate 6 to the other end, is welded to the sleeve 12. (Fig. 2 F) The electrode mount obtained in this way is placed in a container, and after that, after filling the container with dry air using the usual method, the end of the container is sealed, and the thermal protector is installed. can get.

FIG. 3 shows another embodiment of the present invention, in which a block body 10 made of a positive temperature coefficient thermistor is used as a glass bead.

In FIG. 3, parts common to those in FIG. 1 are designated by the same reference numerals.

In FIG. 3, conductive sleeves 16 and 17 are
The other end passes through the hole in the block body 10 and extends outside the block body.
and the sleeve 17 are welded at two locations on the upper and lower ends of the sleeve 17.

With this configuration, there is no fear that the leads of the fixed electrode 4 and the leads 5 will be displaced from the predetermined positions of the sleeves 16 and 170, and therefore the glass bead can be made unnecessary.

4A to 4F show the manufacturing procedure of the thermal protector shown in FIG. 3, which is assembled in the same manner as in the case of FIGS. 2A to 2F.

In the figure, parts common to those in FIGS. 1, 2A to 2F, and 3 are denoted by the same reference numerals.

In the thermal protector having the above configuration, conductive sleeves 11, 12 or 16, 17 are inserted into the holes 10a, 10b of the block body 10 and are in electrical contact with the block body, and fixed electrodes are attached to the sleeves 11, 12. 4 and the lead 5 are inserted, respectively, and the sleeve 11 and the lead of the fixed electrode 4 and the sleeve 12 and the lead 5 are in electrical contact, respectively, so that the block body 10 and the fixed electrode 4
The electrical, thermal, and mechanical connections with the movable electrode 8 are reliable, so the reliability of the operating temperature is high (and the vibration resistance is also high).

An alternating current voltage of 100 V was applied between the fixed electrode and the movable electrode of the thermal protector of the above embodiment shown in FIG. 2, which was designed with an opening operating temperature of 130°C and a closing operating temperature of 90'C.
When the thermal protector was tested by applying A constant temperature of over 90° C., for example 100° C., was maintained, and as a result, the open state between both contacts was maintained normally while a voltage was applied between both electrodes.

The return of both contacts to the closed state is effected by opening the power switch.

On the other hand, a thermal protector designed for the same operating temperature as above and in which the fixed electrode and movable electrode leads are directly inserted into the hole of the block body consisting of a positive temperature coefficient thermistor without fitting the sleeve, is used under the same conditions as above. When tested using this method, poor contact occurred between the silver coated electrode coated on the surface of the pores of the flock body and the movable electrode or lead, sparks were generated between the two, and insufficient voltage was applied between the two. Therefore, constant temperature heat generation of the positive temperature coefficient thermistor could not be obtained, and a normal open state between the two electrodes could not be maintained.

As explained above, the present invention has extremely good electrical, thermal, and mechanical connections between the block body made of a resistive element having a positive temperature coefficient and each electrode, and therefore has high reliability in operating temperature. , and can provide a thermal protector with high vibration resistance.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a thermal protector according to an embodiment of the present invention, FIGS. 2A-F are perspective views showing the manufacturing process of the electrode mount of the thermal protector shown in FIG. 1, and FIG. Side sectional view of a thermal protector of another embodiment, No. 4
FIGS. AF are perspective views showing the manufacturing process of the electrode mount of the thermal protector shown in FIG. 3. 1... Container, 2... Electrode mount, 4
...Fixed electrode, 5...Lead, 7...
...Thermal response element, 8...Movable electrode, 9...
...Glass beads, 10...Flock body,
11,12...Sleeve.

Claims (1)

[Claims] a block body comprising a resistance element having a positive temperature coefficient and having 12 holes; two conductive sleeves each inserted into the holes of the block body and in electrical contact with the block body; and one of the sleeves. a fixed electrode having a lead inserted into the sleeve and in electrical contact with the sleeve;
a thermally responsive element that separates from the fixed electrode and opens the electrical connection with the fixed electrode when a predetermined set temperature is reached, and is electrically connected to the thermally responsive element;
A thermal protector further comprising: a movable electrode having a lead that is inserted into the other sleeve and comes into electrical contact with the sleeve.