JPH09282992A - Temperature fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase spring force of a breaking coil spring by inserting an elastic body, a temperature sensing pellet and a spring movable piece inside a sleeve electrode, and sealing an electrode projecting from a sealing ceramic in such a manner as to bring it into contact with the movable piece via a metal piece. SOLUTION: An elastic member 5 such as a silicon rubber is inserted into the bottom of a sleeve electrode 6, and then, a temperature sensing pellet 4 abuts against the electrode 6. A spring movable piece 3 formed by twisting a cut metal ring as a movable contact is compressed and inserted in a radial direction, and metal pieces 2 each having a through hole 9 abut against right and left of the movable piece 3. Furthermore, a sealing ceramic 8 having an electrode 1 projecting at the center thereof is press-fitted while compressing a coil spring 7. Spring force of the spring 7 is larger than that of the movable piece 3 while smaller than the sum of that of the movable piece 3 and that of the elastic member 5 having a remarkably large nonlinear spring constant, so that the spring force after sealing of the spring 7 becomes large. Contact resistance between the movable piece 3 and the electrode 6 is small. The pellet 4 is dissolved at a predetermined temperature, to flow through the through hole 9, thus instantaneously separating the electrode 1 from the metal piece 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal fuse that is cut off when a predetermined temperature is reached.

[0002]

2. Description of the Related Art A temperature sensitive pellet, a contact maintaining coil spring, and a movable circular piece are sequentially inserted into a sleeve electrode, and the sleeve electrode is sealed while compressing a blocking coil spring with a sealing ceramic. When sealed, the contact maintaining coil spring has a larger spring force than the breaking coil spring, and the electrode at the tip of the sealing ceramic is always kept in contact with the movable circular piece. When the temperature-sensitive pellets are melted, the movable circular pieces are moved in discrete directions by the spring force of the blocking coil spring, and the contact with the electrodes is broken. A method of partially fixing the contact maintaining coil spring itself with a temperature sensitive pellet is also adopted.

[0003]

In order to improve the fusing characteristics, the stronger the spring force of the breaking coil spring is, the more preferable it is, but the spring force of the contact maintaining coil spring cannot be exceeded. Variations in fusing due to insufficient spring force are noticeable. It is the present invention to provide a thermal fuse capable of taking a large spring force of the breaking coil spring, which will be described in detail below with reference to the drawings.

[0004]

[Means for Solving the Problems] An elastic body made of silicon rubber or the like, a temperature-sensitive pellet that melts at a predetermined temperature, and a spring movable piece compressed in a radial direction are sequentially inserted into a sleeve electrode for sealing. The coil spring is compressed and sealed in the sleeve electrode so that the electrode protruding in the center of the ceramic comes into contact with the spring movable piece directly or through the metal piece.
The spring force of the breaking coil spring can be made larger than the spring force of the spring movable piece in which the metal ring is twisted.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION An elastic body 5 such as silicon rubber is inserted into the bottom of a sleeve electrode 6 to which a lead wire 10 is connected. The elastic properties of silicone rubber as a cushion material are
It has a non-linear shape different from the coil spring, and the amount of deformation with respect to the load is extremely small. The temperature-sensitive pellet 4 that melts when reaching a predetermined temperature is brought into contact with the sleeve electrode 6. Spring movable piece 3 formed by twisting a cut metal ring
Is inserted into the sleeve electrode 6 as a movable contact, but before insertion, it is expanded in both the radial direction and the sleeve axial direction as shown in FIG. Therefore, the spring movable piece 3 is inserted by being compressed in the radial direction. A metal piece 2 having a through hole 9
The springs 2 are brought into contact with the left and right sides of the spring movable piece 3 and inserted into the sleeve electrode 6. Sealing ceramic 8 with electrode 1 protruding from the tip
Is press-fitted into the sleeve electrode 6. The electrode 1 is connected to the lead wire 11. The electrode 1 continues to push the metal piece 2, and the coil spring 7, the spring movable piece 3 and the elastic body 5 are compressed. Both ends of the elastic body 5 are initially displaced (Fig. 2),
Due to this compression, they face each other as shown in FIG. The spring force of the coil spring 7 after press-fitting is larger than that of the spring movable piece 3 alone and smaller than the sum of it and the elastic body 5. Since the non-linear spring constant of the elastic body 5 is remarkably larger than that of the spring movable piece 3 or the conventional coil spring, the spring force after enclosing the coil spring 7 can be made large.

Next, the operation will be described. Spring movable piece 3
Is compressed in the radial direction and inserted into the sleeve electrode 6, so that it always maintains contact with the inner wall surface of the sleeve electrode. The contact resistance is 0.7 milliohms or less. The electrode 1 and the sleeve electrode 6 can be kept electrically connected via the metal piece 2 that abuts on the spring movable piece 3. When the temperature reaches the predetermined temperature, the temperature-sensitive pellet 4 is melted, the elastic energy of the coil spring 7 is dissipated at once, and the electrode 1 and the metal piece 2 are instantly separated. The melted temperature-sensitive pellet component flows to the spring movable piece 3 side through the through hole 9 of the metal piece 2 (Fig. 3). Since the spring force of the coil spring 7 is large, the dissolved component is
Is pushed out at once.

[0007]

In summary, according to the present invention, the elastic body 5 made of silicon rubber or the like, the temperature-sensitive pellet 4 which melts at a predetermined temperature, and the spring movable piece 3 compressed in the radial direction are sequentially placed in the sleeve electrode 6. The electrode 1 which is inserted and protrudes in the center of the sealing ceramic 8 is directly connected to the spring movable piece 3 or the metal piece 2
Since the coil spring 7 is compressed and sealed in the sleeve electrode 6 so as to come into contact with each other, the spring force of the coil spring 7 can be made larger than in the conventional case, and the interruption is instantaneously and reliably performed. . The contact resistance between the sleeve electrode 6 and the spring movable piece 3 is small by adopting the spring movable piece 3 which is formed by cutting and twisting the metal ring. Since the elastic body 5 is sandwiched between the left and right metal pieces 2, the movement at the time of interruption is smoothly performed.

[Brief description of drawings]

FIG. 1 is a sectional view.

FIG. 2 is an explanatory diagram illustrating an arrangement of a spring movable piece and the like.

FIG. 3 is a cross-sectional view in a shut-off state.

[Explanation of symbols]

 1 Electrode 2 Metal Piece 3 Spring Movable Piece 4 Temperature Sensitive Pellet 5 Elastic Body 6 Sleeve Electrode 7 Coil Spring 8 Sealing Ceramic 9 Through Hole

Claims (4)

[Claims] 1. An elastic body 5 made of silicone rubber or the like, a temperature-sensitive pellet 4 that melts at a predetermined temperature, and a spring movable piece 3 compressed in a radial direction are sequentially inserted into a sleeve electrode 6 and sealed. A thermal fuse that compresses and seals a coil spring 7 in a sleeve electrode 6 so that an electrode 1 protruding in the center of a ceramic 8 contacts the spring movable piece 3 directly or via a metal piece 2. 2. An elastic body 5, a temperature-sensitive pellet 4, a ring-shaped spring movable piece 3, and a metal piece 2 having a through hole 9 are sequentially inserted into a sleeve electrode 6 connected to one lead wire, The electrode 1 connected to the other lead wire is arranged at the tip of the sealing ceramic 8, the sealing ceramic 8 is pressed into the sleeve electrode 6 against the coil spring 7, and the tip of the electrode 1 contacts the metal piece 2. A thermal fuse that contacts. 3. A temperature-sensitive pellet 4, a ring-shaped spring movable piece 3 which is compressed in the radial direction, and a metal piece 2 are sequentially inserted into a sleeve electrode 6 connected to one lead wire, and the other lead is inserted. The electrode 1 connected to the wire is arranged at the tip of the sealing ceramic 8, the sealing ceramic 8 is pressed into the sleeve electrode 6 against the coil spring 7, and the tip of the electrode 1 is brought into contact with the metal piece 2. Become a thermal fuse. 4. An elastic body 5 of silicon rubber, a temperature-sensitive pellet 4 which melts at a predetermined temperature, a spring movable piece 3 which is twisted in a cutting ring and is compressed in a radial direction, and a sleeve electrode 6 in order. A thermal fuse that compresses and seals the coil spring 7 in the sleeve electrode 6 so that the electrode 1 protruding into the center of the sealing ceramic 8 contacts the spring movable piece 3 inside.