JPH0456411B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention detects an abnormal temperature rise during the use of industrial equipment and household electrical appliances, and interrupts the electric circuit to prevent equipment damage accidents. This invention relates to a thermal pellet type thermal fuse for preventing fires. [Prior Art] Conventionally, this type of temperature fuse has been used having a structure as shown in FIGS. 3 and 4.
Reference numeral 1 denotes a case, which has a U-shaped cylinder shape with an opening on the input side and a bottom surface on the output side. A temperature-sensitive pellet 2 is housed on the output side of the case 1, and an insulating bushing 3 is housed on the input side. In addition, on the bottom of the case 1,
A lead terminal 4 is crimped, and a lead terminal 5 is inserted inward through the insulating bushing 3 from the opening, and the opening is closed with a sealing resin 6. Further, between the temperature-sensitive pellet 2 and the insulating bushing 3, a strong compression spring 10 and a weak compression spring 11 on the input side are interposed between the movable contact piece 7 and the pressure plates 8 and 9 on the output side. The terminal 5 is housed so as to be in contact with a fixed contact 12 provided at the tip of the lead terminal 5. [Problems to be Solved by the Invention] However, the case 1 does not have the insulating bushing 3.
Since it is open at the upper surface position, the sealing resin 6 is applied without any frame to hold the outer periphery, and the opening is closed only by the sealing resin 6. The shape is uneven. As a result, the thickness of the sealing resin 6 becomes non-uniform, resulting in thinner portions, which may crack under the slightest external force. As a result, a serious problem has occurred in which the lead terminal 5 on the input side becomes loose at the part where it is fixed to the sealing resin 6, or the lead terminal 5 comes off due to this. [Means for Solving the Problems] The present invention was invented for the purpose of solving these problems and providing a product that maintains stable functions. An extension part 13 of the sealing resin 6 is provided extending further from the upper surface toward the input side, and an inward protrusion 14 is formed on the entire or part of the lower end of this extension part 13, and the upper end of the case 1 is deformed inward. This is what I did. [Function] The insulating bushing 3 is attached to the case 1 by the protrusion 14.
By filling the extension part 13 with sealing resin 6 and making the sealing resin 6 maintain its tensile strength by the upper end of the case 1, the thickness of the sealing resin 6 can be made uniform and the thickness can be increased. Eliminates the occurrence of thin parts and prevents conditions such as cracks in those parts, and as a result, prevents the lead terminals 5 from becoming loose or coming off due to this, especially at the parts where they are fixed to the sealing resin 6. It is effective. [Examples] Examples of the present invention will be described below based on the drawings.
In FIGS. 1 and 2, reference numeral 1 denotes a case, which has a U-shaped cylinder shape with an opening on the input side and a bottom surface on the output side. A temperature-sensitive pellet 2 is housed on the output side of the case 1, and an insulating bushing 3 is housed on the input side. Further, a lead terminal 4 is crimped on the bottom surface of the case 1, while a lead terminal 5 is inserted from the opening.
is inserted into the insulating bushing 3 inwardly,
The opening is closed with sealing resin 6.
Further, between the temperature-sensitive pellet 2 and the insulating bushing 3, the movable contact piece 7 interposes a strong compression spring 10 held by the pressure plates 8 and 9 on the output side and a weak compression spring 11 on the input side. The terminal 5 is housed so as to be in contact with a fixed contact 12 provided at the tip of the lead terminal 5. Next, main parts of the present invention will be explained. Said case 1
As shown in FIGS. 1 and 2, extends further from the upper surface of the insulating bushing 3 toward the input side,
An extension portion 13 of the sealing resin 6 is provided at the extension portion. The extension part 13 has an inward protrusion 14 formed on the entire circumference or a part of the lower end, and the upper end of the case 1 is deformed so as to be folded inward. As a result, the insulating bushing 3 is fixed in the case 1 by the protrusion 14, the extension part 13 is filled with the sealing resin 6, and the sealing resin 6 is made to maintain tensile strength by the upper end of the case 1. ,
The thickness of the sealing resin 6 is made uniform, eliminating the occurrence of thin parts, preventing conditions such as cracks in those parts, and especially preventing loosening of the lead terminal 5 at the part where it is fixed to the sealing resin 6. This exhibits an effect of preventing the lead terminal 5 from coming off due to this cause. The normal current path of the temperature fuse configured as described above is as shown in FIG.
The input side is as follows. Lead terminal 5 → Movable contact piece 7 → Case 1 → Lead terminal 4 The current connection between lead terminal 5 and case 1 is as follows:
The movable contact piece 7 is pressed against the fixed contact 12 of the lead terminal 5 by the pressure of the strong compression spring 10, and
This is because the outer edge of the movable contact piece 7 is always in contact with the inner surface of the case 1 by a spring action. On the other hand, the current path in the event of an abnormality is as shown in FIG. 2. When the temperature reaches the rated temperature, the temperature-sensitive pellet 2 melts, the strong compression spring 10 is released, and the weak compression spring 11, which had been maintaining equilibrium, is released. is released, the movable contact piece 7 moves toward the strong compression spring 11, and as a result,
The lead terminal 5 is no longer in contact with the fixed contact 12, and the electrical path with the case 1 is cut off. [Effects of the Invention] As explained above, the present invention extends the case 1 further from the upper surface of the insulating bushing 3 toward the input side to provide the extended portion 13 of the sealing resin 6, and this extended portion 1
Since the inward protrusion 14 is formed on the entire circumference or a part of the lower end of the case 1, and the upper end of the case 1 is deformed inward, the insulating bushing is fixed inside the case by the protrusion, and the extension part is sealed. By filling the resin and having the sealing resin retain its tensile strength at the upper end of the case, the thickness of the sealing resin can be made uniform, eliminating the occurrence of thin parts and preventing cracks or other problems in those parts. As a result, lead terminals may become loose, especially at the part where they are stuck to the sealing resin, or
It exhibits the effect of preventing the lead terminal from coming off due to this cause, and as a result, it has the effect of obtaining a product with stable quality.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the temperature fuse of the present invention, FIG. 2 is a sectional view of the temperature fuse of FIG. 1 after operation, and FIG. 3 is a sectional view of a conventional temperature fuse. , FIG. 4 is a sectional view showing the state after the operation of FIG. 3. 1... Case, 2... Temperature-sensitive pellet, 3... Insulating bushing, 4... Lead terminal, 5... Lead terminal, 6...
Sealing resin, 7... Movable contact piece, 8, 9... Pressing plate, 10
...Strong compression spring, 11...Weak compression spring, 12...Fixed contact, 13...Extension part, 14...Protrusion.

Claims (1)

[Claims] 1 A case 1 having a U-shaped cylinder shape having an opening on the input side and a bottom on the output side stores a temperature-sensitive pellet 2 on the output side and an insulating bushing 3 on the input side. Then, a lead terminal 4 is crimped to the bottom surface of the bushing, and a lead terminal 5 is inserted inward through the opening into the insulating bushing 3, and the opening is closed with a sealing resin 6. A fixed contact 12 is provided at the tip of the lead terminal 5 via a strong compression spring 10 in which the movable contact piece 7 is held between the insulating bushing 3 by pressing plates 8 and 9 on the output side and a weak compression spring 11 on the input side. In the temperature fuse housed so as to be in contact with the case 1, the case 1 is further extended from the upper surface of the insulating bushing 3 toward the input side to provide an extended portion 13 of the sealing resin 6, and the extended portion 13 of the lower end of the extended portion 13 is provided with a A temperature fuse characterized in that an inward protrusion 14 is formed and the upper end of the case 1 is deformed inward.