JPS591304Y2 - temperature fuse - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a non-resetting type temperature fuse using a temperature-sensitive agent that melts at a specific temperature.

Overtemperature rise prevention devices are used from the viewpoint of the safety of electrical equipment.

Overtemperature rise prevention devices can be roughly divided into resetting types such as bimetal switches and non-resetting types using fusible alloys. A non-resetting type temperature fuse using a temperature-sensitive agent has been widely used.

Since the present invention relates to an improvement of this type of temperature fuse, before providing a detailed explanation of the present invention, we will provide an overview of the structure and operation of conventional temperature fuses within the scope necessary for understanding the present invention. explain.

FIG. 1 shows a longitudinal sectional view of a typical example.

In the figure, reference numeral 1 denotes a cylindrical metal case made of a metal with good electrical conductivity and good thermal conductivity, such as copper, and a first lead wire 2 is caulked and fixed to one end of the case.

3 is a temperature-sensitive agent made of an insulating chemical substance that melts at a specific temperature, which is a characteristic of this type of temperature fuse.It is made by press-molding powder of a chemical substance whose melting point matches the operating temperature into a cylindrical shape. It is formed.

4 and 5 represent the elastic force of the compression springs 6 and 11, which will be described later, by the temperature sensitive agent 3.
and a press plate for dispersing pressure to apply an average pressure to the movable contact 7, which will be described later.

Reference numeral 6 denotes a non-compression spring for closing the circuit, which is interposed in a compressed state between the push plates 4 and 5.

Reference numeral 7 denotes a movable contact disposed on the outer side of the push plate 5, which is made of a metal having good conductivity and appropriate elasticity, such as an alloy mainly composed of silver, and is shaped like a circular shape with a plurality of tongues on the periphery. The tongue piece is bent and brought into elastic contact with the inner wall surface of the metal case 1.

Reference numeral 8 denotes an insulating plug made of ceramic or the like that closes the open end of the metal case 1. A second lead wire 9 passes through the center hole of the plug, and a fixed contact 10 is attached to the inner end of the lead wire 9.
is provided.

Reference numeral 11 denotes a weak compression spring for opening the circuit, which is interposed in a compressed state between the movable contact 7 and the insulating plug 8.

Reference numeral 12 denotes an insulating sealant made of epoxy resin or the like and coated on the outer surface of the insulating plug 8.

In the above configuration, the temperature-sensitive agent 3 is solid at room temperature, and the elastic force of the non-compression spring 6 is blocked by the temperature-sensitive agent 3.
The movable contact 7 is strongly pressed against the fixed contact 10 against the elastic force of the weak compression spring 11.

As a result, the lead wire 2 and the lead wire 9 are maintained in a conductive state along the path of the lead wire 2 - the metal case 1 - the movable contact 7 - the fixed contact 10 - the lead wire 9.

This state is maintained even if the ambient temperature rises due to energization of the electrical equipment, as long as the temperature is within the normal temperature rise range.

In the unlikely event that the ambient temperature exceeds the melting point of the temperature-sensitive agent 3 due to an abnormal temperature rise due to a failure of electrical equipment, the temperature-sensitive agent 3 will melt, and the non-compression spring 6 will block the elastic force of the temperature-sensitive agent 3. When the action is released, it extends to the left in the figure, and the pressing force against the movable contact 7 is eliminated.

Therefore, the elastic force of the weak compression spring 11 exceeds the elastic force of the non-compression spring 6, and the weak compression spring 11 is expanded, pushing the movable contact 7 to the left in the figure.

As a result, the movable contact 7 is separated from the fixed contact 10, and the lead wire 2 and the node wire 9 are brought into a non-conducting state.

The state after this operation is shown in FIG.

This state is maintained even if the ambient temperature drops due to the operation of the temperature fuse, maintaining so-called non-returnable safety.

This type of temperature fuse uses a temperature sensitive agent 3 made of a chemical substance, and has the advantage that by using temperature sensitive agents 3 with different melting points, any temperature fuse can be obtained with the same structure in principle. have

However, since the movable contact is made of an alloy mainly composed of silver, the material cost not only increases, but also requires first punching out a silver alloy plate to have a plurality of tongues 7a on the periphery as shown in FIG. This method has disadvantages in that the material utilization rate is poor, and as shown in FIG. 4, the tip of each tongue 7a is bent, which makes machining troublesome, and the movable contact becomes expensive.

Furthermore, as shown in FIG. 4B, the movable contact 7 is molded so that the outer diameter φ2 of each tongue piece 7a is larger than the inner diameter φ1 of the metal case 1 (φ2>φ1), so that the temperature sensitive agent 3 When melting, the frictional resistance between the metal case 1 and the movable contact 7 is large, and therefore the movable contact 7 does not open quickly from the fixed contact 10, which tends to generate sparks during operation, and also prevents the movable contact 7 from being fixed after operation. The distance between the contact point 10 and the contact point 10 is insufficient, which tends to result in voltage resistance failure.

Furthermore, if the frictional resistance between the metal case 1 and the movable contact 7 is large, the elastic force of the weak compression spring 11 that overcomes it and the elastic force of the non-compression spring 6 that overcomes the elastic force of the weak compression spring 11 are naturally also large. There is a need.

Increasing the elastic force of the non-compression spring 6 in this way also increases the pressing force against the temperature-sensitive agent 3, so depending on the material of the temperature-sensitive agent 3, the temperature fuse may reach the operating temperature (i.e., the melting point of the temperature-sensitive agent 3). If exposed to near high temperatures for a long time, temperature sensitive agent 3
This has the drawback of softening and deforming, resulting in increased contact resistance and malfunction.

Therefore, instead of the plate-shaped movable contact having a complicated shape as described above, for example,
FIG. 16 shows a temperature fuse that uses a plurality of movable contact members smaller than the dimension between the inner surfaces of the case in combination with a conductive plate, and in particular, FIGS. 12 to 16 use a ball-shaped movable contact member. Something has been disclosed.

According to these temperature fuses, the drawbacks of the temperature fuses using complex-shaped movable contacts manufactured by punching out a silver alloy plate described above are improved, but there is still room for the following improvements.

In other words, all of these temperature fuses use a plurality of movable contact members, and furthermore, a conductive plate is interposed between the movable contact members and the fixed contact members, so the number of parts is large, the cost is high, and the assembly work is required. In particular, when using an asymmetrical movable contact member as shown in FIGS. 8 to 11 and 14, the assembly direction must also be considered, making the assembly work extremely complicated. .

In addition, since each movable contact member is small, its resistance value is not only large, but also the resistance of the conductive plate, the contact resistance between the metal case and the movable contact member, the contact resistance between the movable contact member and the conductive plate, and the contact resistance between the conductive plate and the fixed contact. Since the contact resistance is inserted in series, there is a problem that the internal resistance becomes large.

Therefore, the primary objective of the present invention is to provide an improved contact mechanism.

An object of the present invention is to provide a temperature fuse that is inexpensive and has excellent operating characteristics.

To summarize, the present invention uses a single ball-shaped contact with a diameter greater than or equal to the inner diameter of the case, instead of a conventional movable contact with a complicated shape made by punching out a silver alloy plate, multiple small movable contact members, and a conductive plate. The present invention is characterized in that a movable contact member is used, and the ball-shaped movable contact member is directly brought into contact with and separated from a fixed contact.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 5 shows a longitudinal sectional view of a temperature fuse according to an embodiment of the present invention.

Since the configuration is the same as that in FIG. 1 except for the characteristic parts of the present invention, the same parts as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

The feature of this embodiment is that instead of the movable contact 7 having a complicated shape as shown in FIG. 70 was used.

Next, let's talk about how to assemble the metal case.
A metal case assembly with a lead wire 2 caulked and fixed to one end of the metal case 1 is prepared, silver plated, and supported vertically with the opening of the metal case 1 facing upward.

Next, the temperature sensitive agent 3 and the push plate 49 are inserted into the metal case 1 through the opening.
Strong compression spring 6. Push plate 5. The silver-plated ball-shaped movable contact member 70 and the weak compression spring 11 are sequentially inserted in the order just described.

In this case, since the outer diameter φ2 of the movable contact 7 as shown in FIG. However, the outer diameter of the ball-shaped movable contact member 70 of the present invention is the inner diameter (
Since it is smaller than φ1), it is sufficient to simply drop it in.

The inserted ball-shaped movable contact member 70 is placed in the metal case 1
comes into contact with the inner surface of

Next, an insulating plug assembly is prepared in which the lead wire 9 is inserted into the center hole of the insulating plug 8, and the insulating plug assembly is inserted into the opening of the metal case 1 with the fixed contact 10 facing inward.

Furthermore, the portion of the metal case 1 that protrudes from the outer surface of the insulating plug 8 is caulked along the outer surface of the insulating plug 8.

This caulking operation causes the fixed contact 10 to press a position eccentric from the center of the ball-shaped movable contact member 70, so that the ball-shaped movable contact member 70 is strongly pressed against the inner surface of the metal case 1.

Finally, an insulating sealant 12 is applied to the outer surface of the insulating plug 8 to complete the assembly.

In this state, the lead wire 2 and the lead wire 9 are electrically connected through the lead wire 2 - metal case 1 ball-shaped movable contact member 7 - fixed contact 1 O - IJ - lead wire 9 path. .

In this way, the ball-shaped movable contact member 70 not only has a significantly larger cross-sectional area than the movable contact 7 in FIG. Cheap brass or the like can be used, material costs can be reduced, and processing costs can also be reduced.

When the ambient temperature rises and exceeds the melting point of the temperature sensitive agent 3, the temperature sensitive agent 3 melts.

Then, the elastic force of the high compression cotton spring 6 is released and the elastic force of the weak compression spring 11 exceeds the elastic force of the high compression cotton spring 6, so the weak compression spring 11 expands and moves the ball-shaped movable contact member 70 to the left in the figure. Push it away.

At this time, since the diameter of the ball-shaped movable contact member 70 is smaller than the inner diameter (φ1) of the metal case 1, the movement of the ball-shaped movable contact member 70 is extremely smooth.

Therefore, the fixed contact 10 of the ball-shaped movable contact member 70
The opening operation is quick and no spark is generated.

Further, a sufficient distance can be maintained between the ball-shaped movable contact member 70 and the fixed contact 10 after the opening operation, and the withstand voltage is increased.

As described above, since the present invention uses a ball-shaped movable contact member, it not only reduces the material cost and processing cost compared to the case of using a movable contact with a complicated shape, but also reduces the diameter of the ball-shaped movable contact member. Because it is smaller than the inner diameter of the metal case,
When the temperature-sensitive agent melts, the ball-shaped movable contact member operates quickly and smoothly, without generating sparks, and the separation distance of the ball-shaped movable contact member from the fixed contact can be made sufficiently large, reducing the withstand voltage after operation. can be made larger.

Furthermore, compared to a structure using a combination of a plurality of small movable contact members and a conductive plate, the number of parts is small, assembly work is easy, and the cost is low.

Furthermore, not only is the resistance of the ball-shaped movable contact member itself low, but since no conductive plate is used, there is no resistance, and the contact points are between the metal case and the ball-shaped movable contact member and between the ball-shaped movable contact member and the fixed contact. Since there are only two locations in between, the contact resistance is also reduced, and the internal resistance of the temperature fuse is extremely small, which is an excellent effect.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a temperature fuse, which is the background of this invention.
Figure 2 is a vertical cross-sectional view showing the state of the temperature fuse in Figure 1 after operation, Figure 3A is a plan view of the developed shape of the movable contact used in the temperature fuse in Figure 1, and Figure 3B is its longitudinal cross-section. 4A is a plan view of the movable contact after molding, FIG. 4B is a vertical cross-sectional view thereof, and FIG. 5 is a vertical cross-sectional view of a temperature fuse according to an embodiment of the present invention. 1... Metal case, 2, 9... Lead wire, 3... Temperature sensitive agent, 4, 5... Push plate,
6... Strong compression cotton spring, 8... Insulating plug, 10... Fixed contact, 11... Weak compression spring, 70... Ball shaped movable contact member.

Claims (1)

[Claims for Utility Model Registration] A temperature-sensitive agent that melts at a specific temperature, a non-compression spring, a movable contact, a weak compression spring, and an open end of the case are closed in a case whose inner surface is conductive at least. A temperature fuse comprising an insulating plug and a lead wire passing through the insulating plug and having a fixed contact at an inner end that makes contact with and separates from the movable contact, the movable contact having a diameter smaller than the inner diameter of the case and A temperature fuse characterized by using a single ball-shaped movable contact member that is larger than the inner diameter of the fuse and that directly contacts and separates from a fixed contact.