JP2002075150A - Protective element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small, flat and low-profile protective element which uses shape-memory alloy and reduces the number of components. SOLUTION: Lead wires 4 and 5 are connected to a pair of conductors 2 and 3 formed at positions separated from each other on an insulated substrate 1. One end of a movable contact 6, composed of the plate-shaped shape memory alloy, is connected for fixation to one conductor 2, the other end thereof comes into pressed-contact with the other conductor 3, and an insulating cap 7, which covers the movable contact 6 from above, is fixed and sealed with a sealing resin 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a protection element,
More specifically, the present invention relates to a protection element having a movable contact made of a shape memory alloy that returns to a memory shape at a specific temperature.

[0002]

2. Description of the Related Art As a protection element for protecting electronic equipment from overheat damage, a thermal fuse which operates at a specific temperature and cuts off a circuit is used. For this type of thermal fuse,
A temperature-sensitive pellet type in which a movable contact is separated from a fixed contact by the expansion of a compression spring when the temperature-sensitive pellet is melted by using a temperature-sensitive pellet made of an insulating chemical substance that melts at a specific temperature as a temperature-sensitive material (a ) And a low-melting alloy that melts at a specific temperature as a temperature-sensitive material, and a current is applied to the low-melting alloy. ). There is also a protection element (c) called a fuse with resistance, which includes a low melting point alloy and a resistor, and forcibly blows the low melting point alloy by energizing and heating the resistor. There is also a current fuse (d) that blows due to overcurrent. Further, there is a protection element (e) called a temperature fuse and a current fuse that functions as a temperature fuse for an excessive rise in ambient temperature and functions as a current fuse for an overcurrent.

[0003] However, all of these are non-returnable types which do not return to the original state once a temperature-sensitive material such as a temperature-sensitive pellet or a low melting point alloy operates once upon detecting an excessive rise in temperature. Therefore, although it has the advantage of being safe, there is a problem that the convenience is inferior because it cannot be used repeatedly.

Therefore, even if the ambient temperature rises excessively and the shape memory alloy returns to the memory shape and the movable contact operates once by using the shape memory alloy, the shape memory alloy returns to the initial state due to the decrease in the ambient temperature. A protective element which can be repeatedly used by returning a movable contact to an initial state by being deformed into a shape has also been proposed.

[0005]

However, this type of conventional protection element is not only expensive because of the large number of components, but also requires a large and large installation space, or requires the use of a cylindrical case. Therefore, there has been a problem that the thermal contact state with the installation member is not sufficient, and the detection sensitivity of the excessive temperature rise state is poor.

Accordingly, the present invention provides a protection element having a movable contact made of a shape memory alloy, having a small number of parts, a small size, a flat shape, a low profile, and excellent detection sensitivity in an overtemperature state. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION The present invention has a movable contact made of a plate-shaped shape memory alloy, one end of which is connected and fixed to one conductor, and the other end of which is pressed into contact with the other conductor. Thus, the entire structure is flat.

[0008] Various configurations and effects of the present invention will be described below. The invention according to claim 1 of the present invention comprises a pair of conductors and a plate-shaped shape memory alloy in which one end is connected and fixed to the one conductor and the other end is pressed against the other conductor. And a movable contact, wherein the movable contact is sealed by a cap. As described above, the use of the movable contact made of a plate-shaped shape memory alloy reduces the number of parts, and is flat and low-profile. An excellent protection element is obtained.

According to a second aspect of the present invention, there is provided a pair of conductors formed separately on an insulating substrate, and one end is connected and fixed to the one conductor, and the other end is pressed into contact with the other conductor. A movable contact made of a plate-shaped shape memory alloy,
A cap fixedly sealed to the insulating substrate. As described above, the protection element using the movable contact made of a plate-shaped shape memory alloy in a plane parallel to the insulating substrate has a small number of parts, is small, flat, and has a low profile, and has a flat bottom surface. As a result, the thermal sensitivity is excellent.

According to a third aspect of the present invention, a leaf spring for bias is attached to the other end of the movable contact so that the ambient temperature falls below the temperature at which the shape memory alloy returns to the memory shape. The protection element according to claim 1, wherein the other end of the movable contact is urged so as to again press and contact the other conductor. As described above, in the apparatus provided with the biasing leaf spring, after the movable contact returns to the memorized shape upon detecting an excessive temperature rise, when the ambient temperature decreases, the biasing action of the leaf spring causes the movable contact to return to the other position. The end contacts the other conductor, allowing for repeated use.

According to a fourth aspect of the present invention, there is provided a metal base serving as one conductor, a movable contact made of a plate-shaped shape memory alloy having one end connected and fixed to the metal base,
A metal cap to be the other conductor fixed and sealed on the peripheral portion of the metal base with an insulating member interposed therebetween, wherein the other end of the movable contact is brought into pressure contact with the metal cap. Protection element. As described above, when the metal base and the metal cap are used as the conductor, the insulating substrate and the insulating cap are not required, and the number of components can be further reduced.

The invention according to claim 5 of the present invention is characterized in that the other end of the movable contact is connected and fixed to a metal cap serving as the other conductor with a low melting point alloy. It is a protection element. As described above, when the other end of the movable contact is connected and fixed to the metal cap with the low melting point alloy, the operating temperature can be guaranteed with the low melting point alloy.

According to a sixth aspect of the present invention, there is provided a protection element characterized in that a shape of a movable contact made of a shape memory alloy after returning is different from a shape at room temperature thereafter. As described above, when the shape of the movable contact after the return is different from the shape at the subsequent room temperature, a return-type protection element can be obtained without a leaf spring for bias.

According to a seventh aspect of the present invention, the movable contact returns to the memory shape at a temperature for returning to the memory shape,
7. The protection element according to claim 6, wherein at a temperature lower than that, the protection element returns to a position where the conductor is pressed against the other conductor due to permanent deformation strain. When such a movable contact is used, a return-type protection element can be obtained without a leaf spring for bias.

According to an eighth aspect of the present invention, the movable contact is formed by joining a member made of a shape memory alloy with another member having a lower resistance than the member. 8. The protection device according to any one of claims 1 to 7. As described above, when another member having a lower resistance than the movable contact is coupled to the movable contact, the resistance value of the movable contact can be reduced, and a protection element having a small internal resistance can be obtained.

According to a ninth aspect of the present invention, the movable contact is formed by joining a member made of a shape memory alloy to another member having a different coefficient of thermal expansion from the member. 8. The protection element according to any one of 1 to 7. As described above, when the movable contact has the composite structure, the function of the protection element can be improved by a bimetal effect due to a difference in thermal expansion coefficient between a member made of a shape memory alloy and another member having a different thermal expansion coefficient. Can be.

According to a tenth aspect of the present invention, the member made of the shape memory alloy and another member are soldered, conductive paste, resistance welding, plasma welding, ultrasonic welding, caulking, and painting. The protection element according to claim 8, wherein the protection element is coupled by any one selected from the group consisting of: As described above, when joining a member made of a shape memory alloy and another member having a different thermal expansion coefficient from the member, a joining method according to mutual compatibility can be adopted.

According to an eleventh aspect of the present invention, the movable contact has a lower resistance layer than the movable contact at at least a contact portion with another conductor. It is a protection element in any one of the above. As described above, when the movable contact has the low resistance layer, the contact resistance between the movable contact and another conductor is reduced, and a protection element having a small internal resistance can be obtained.

According to a twelfth aspect of the present invention, the low-resistance layer is made of one of a metal selected from the group consisting of Au, Ag, Pd, Pt, Cu, and Ni, and an alloy containing these as a main component. , Or Ag-CdO, Ag containing them as main components
The protection element according to claim 11, wherein the protection element is formed of any one of a composite material such as -CuO or a solder material. As described above, when the low resistance layer is formed of the above-described material, the contact resistance between the movable contact and another conductor is reduced, and a protection element with small internal resistance can be obtained.

According to a thirteenth aspect of the present invention, there is provided the protective element according to the twelfth aspect, wherein the low resistance layer is formed by any one of plating, vapor deposition, and sputtering. As described above, when the low-resistance layer is formed, the low-resistance layer can be easily and thinly formed.

According to a fourteenth aspect of the present invention, the other end of the movable contact is in surface contact with another conductor. Of the protection element. As described above, when the other end of the movable contact is in surface contact with the other conductor, the contact area between the movable contact and the other conductor is large, the contact resistance is small, and the protection element having a small internal resistance. Is obtained.

According to a fifteenth aspect of the present invention, the movable contact operates at one or both of an excessive rise in ambient temperature and an overcurrent. It is a protection element of description. As described above, when the movable contact operates at one or both of the excessive rise of the ambient temperature and the overcurrent, a multifunctional protection element is obtained.

According to a sixteenth aspect of the present invention, there is provided a PTC element, a movable contact made of a plate-shaped shape memory alloy having one end connected and fixed to the PTC element;
A metal cap fixedly sealed with an insulating member interposed therebetween at a peripheral portion of the C element, wherein the other end of the movable contact is connected to the metal cap by a press contact or a low melting point alloy. Protection element. Thus, PT
In a protection element using a C element, the resistance value against an overcurrent is increased by a PTC element to perform a protection function.

According to a seventeenth aspect of the present invention, at least one through hole is formed in an insulating substrate, and a conductor led out through the through hole is connected to one end of the conductor and the other end is fixed. A protection element, comprising: a movable contact made of a plate-shaped shape memory alloy having the other end pressed against a conductor; and a cap sealed to the insulating substrate. As described above, when the conductor is derived using the through-hole, no lead is required and surface mounting is possible.

The invention according to claim 18 of the present invention is characterized in that the metal cap is sealed by press-fitting into the insulating substrate or the metal base. It is a protection element. in this way,
When the metal cap is sealed by press-fitting, heating is not performed at the time of sealing, so that sealing is facilitated and distortion due to heating does not remain in the movable contact made of the shape memory alloy.

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

FIG. 1 is a sectional view of a protection element A according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a rectangular or circular insulating substrate made of a ceramic, a heat-resistant resin, or the like, and a conductive paste such as a silver paste, a silver-palladium paste, or a silver-platinum paste formed by coating on a spaced position on the surface. A pair of conductors 2, etc.
3 are formed. The conductors 2 and 3 have
Leads 4 and 5 made of copper, nickel or the like are connected by soldering or the like. The inner end of the one conductor 2 is soldered or the like so that one end of a movable contact 6 made of a plate-shaped shape memory alloy such as a Ti—Ni alloy is in a plane parallel state with the insulating substrate 1. The other end of the movable contact 6 is pressed and contacted with the other conductor 3. Reference numeral 7 denotes an insulating cap made of a heat-resistant resin or the like, and when the movable contact 6 returns to the shape at the temperature for returning to the memory shape,
A space capable of being separated from the other conductor 3 by a sufficient dimension is formed. The insulating cap 7 is fixedly sealed to the insulating substrate 1 by a sealing resin 8 made of epoxy resin or the like.

In the protection element A, the leads 4, 5
Are connected in series to the electronic device, and the insulating substrate 1 is attached to a place where the temperature rises when the electronic device is abnormal. Then, the lead 4-conductor 2-movable contact 6-conductor 3-
An electric current flows through the path of the lead 5, and the electronic device can be energized.

When the ambient temperature rises excessively due to an abnormality of the electronic equipment, the movable contact 6 made of a shape memory alloy returns to a curved shape as a memory shape, and as shown in FIG. Are separated from the other conductor 3. Therefore, the current path is opened, the power supply to the electronic device is cut off, and the temperature of the electronic device is prevented from rising further, and the occurrence of fire due to the ignition of the electronic device is prevented. Also, by appropriately setting the resistance value of the movable contact 6,
When an overcurrent flows, it returns to the memory shape by self-heating,
The other end of the movable contact 6 may be separated from the other conductor 3 and protected.

Here, in the protection element A, as shown in FIG. 1, the movable contact 6 made of a plate-shaped shape memory alloy is connected and fixed so as to be in a plane parallel state with the insulating substrate 1. Since the entire protection element A is formed in a small size with a small number of components, is flat and has a low profile, and has a flat bottom surface, the electronic device is excellent in heat sensitivity.

[0030]

[Embodiment 2] Next, a second embodiment according to claim 3 of the present invention will be described.
The protection element B according to the embodiment will be described. The protection element B is a return-type protection element in which the movable contact returns to the initial state again due to a decrease in ambient temperature by combining the protection element A of FIG. 1 with a bias leaf spring. FIG. 3 is a sectional view of a protection element B according to a second embodiment of the present invention. In FIG. 3, the same parts as the protection element A in FIG.
The tenth digit is the tenth digit and the first digit is assigned the same code. That is, 11 is an insulating substrate, 12 and 13 are conductors, 14 and 15 are leads, 16 is a movable contact made of a plate-shaped shape memory alloy, 17 is an insulating cap, 18 is a sealing resin, and the description thereof is omitted. . Reference numeral 19 denotes a biasing leaf spring which is a characteristic member of the present embodiment. One end of the leaf spring is fixed to the other end of the movable contact 16 and the other end is fixed to the insulating cap 17. Thus, the other end of the movable contact 16 is always urged toward the other conductor 13 side.

According to the protection element B, the leads 14,
15 is connected to the electronic device in series, and the insulating substrate 11 is attached to a place where the temperature rises when the electronic device is abnormal.
Then, the lead 14-the conductor 12-the movable contact 16-the conductor 1
Electricity can be supplied to the electronic device through the path of the 3-lead 15.

In the event of an abnormality in the electronic device, the movable contact 16 returns to a memory-like curved shape against the elastic force of the biasing leaf spring 19, and the other end is separated from the other conductor 13. Since the energization path is opened and the energization to the electronic device is cut off, a further rise in temperature of the electronic device is prevented, and a fire due to ignition of the electronic device is prevented. In addition, by appropriately setting the resistance value of the movable contact 16, when an overcurrent flows, the movable contact 16
Can return to the memory shape due to self-heating and can be protected in the same manner as described above.

When the ambient temperature falls below the shape return temperature due to the stoppage of power supply to the electronic device, the shape maintaining stress of the movable contact 16 exceeds the elastic force of the leaf spring 18 for bias. The portion again presses and contacts the other conductor 13 to form an energizing circuit. In this way, the protection element B can be used repeatedly as a return type.

[0034]

Embodiment 3 Next, a third embodiment of the present invention will be described.
The protection element C according to the embodiment will be described. The protection element C according to the third embodiment is the same as the protection elements A and B according to the first and second embodiments shown in FIGS. 1 and 3, but also includes the insulating substrates 1, 21, the conductors 2, 3, 12, 13 and the leads 4, 5. , 14, 15 are omitted, and a metal base and a metal cap are used. FIG. 4 is a sectional view of a protection element C according to the third embodiment. In FIG. 4, reference numeral 21 denotes a metal base having good conductivity, such as copper, serving as one conductor, on which one end of a movable contact 22 made of a plate-shaped shape memory alloy is connected and fixed by soldering, welding, or the like. A metal cap 24 of good conductivity such as copper is fixedly sealed on the peripheral portion of the metal base 21 via an insulating member 23. The other end of the movable contact 22 is connected and fixed to the inner surface of the metal cap 24 by a low melting point alloy 25.

In the protection element C, for example, the metal base 21 and the metal cap 24 are connected in series with the electronic device, and the metal base 21 is attached to a place where the temperature rises due to an abnormality in the electronic device. Then, the electronic device can be energized through the path of the metal base 21, the movable contact 22, and the metal cap 24.

When the temperature of the electronic device rises excessively due to an abnormality of the electronic device, the movable contact 22 attempts to return to the stored linear shape. Is maintained. When the ambient temperature further rises and reaches the melting point of the low-melting point alloy 25, the low-melting point alloy 25 melts and loses the restraining force of the movable contact 22 against the shape restoring force. Then, since the movable contact 22 returns to the flat plate shape stored by the movable contact 22 due to the shape restoring force, the movable contact 22 is separated from the metal cap 24 and the power supply to the electronic device is stopped. And to prevent fires caused by ignition of electronic devices. In addition, by appropriately setting the resistance value of the movable contact 22, when an overcurrent flows, the movable contact 22 returns to a memory shape due to self-heating, so that it can be protected as described above. it can.

Also in the protection element C of the third embodiment, a small, flat, and low-profile protection element can be obtained. In addition, since the metal base 21 is used, the formation of the conductors 2, 3, 12 and 13 is not required as compared with the case where an insulating substrate is used, and the thermal response is excellent.
In addition, since it has a leadless structure, it can be easily connected to an electronic device by sandwiching the metal base 21 and the metal cap 24 between a pair of conductors. If necessary, the leads can be connected to the metal base 21 and / or the metal cap 24.

[0038]

Modification of Embodiment 3 This modification is directed to claim 4 of the present invention.
It corresponds to. That is, in the protection element C of the third embodiment, the case where the other end of the movable contact 22 is connected and fixed to the metal cap 24 with the low melting point alloy 25 has been described, but the low melting point alloy 25 may be omitted. . In this case, at the shape return temperature of the movable contact 22 made of a shape memory alloy, the movable contact 22 returns to the memory shape, and the other end of the movable contact 22 is separated from the metal cap 24, thereby opening the circuit and protecting the circuit. I do.

[0039]

Embodiment 4 Next, a protection element D according to a fourth embodiment of the present invention will be described. The protection element D according to the fourth embodiment has a movable contact made of a shape memory alloy that not only returns to a memory shape due to an excessive temperature rise but also returns to the original shape of the protection element when the ambient temperature decreases. The one having a large deformation strain is used.
FIG. 5 is a sectional view of a protection element D according to the fourth embodiment.
In FIG. 5, reference numeral 31 denotes an insulating substrate on which a pair of conductors 32 and 33 are formed at spaced positions. These conductors 3
The reference numerals 2 and 33 extend through the end surface of the insulating substrate 31 to the rear surface. One end of a movable contact 34 made of a plate-shaped shape memory alloy is connected and fixed to one conductor 32. A metal cap 36 is fixedly sealed on the one conductor 32 via an insulating member 35 and directly on the other conductor 33 or via a conductive material. The other end of the movable contact 34 is in pressure contact with the inner surface of the metal cap 36. Here, the movable contact 34 in the protection element D of the present embodiment is bent upward beyond the metal cap 36 as shown by a two-dot chain line 34 'in a state where the metal cap 36 is not attached. The movable contact 34 is processed with an appropriate pressing force by covering the metal cap 36 with the metal cap 36.
Is set so as to press and contact the inner surface of the. Accordingly, the movable contact 34 returns to the flat plate shape, which is a memory shape at the shape return temperature, and is separated from the metal cap 36. However, when the ambient temperature becomes lower than the shape return temperature, the residual strain causes the two-dot chain line 34 'in FIG. It tries to deform into a shape and again comes into pressure contact with the metal cap 36. That is, the shape after restoration is different from the shape in a temperature range lower than the shape restoration temperature.

The protection element D according to the fourth embodiment comprises a conductor 3
The conductors 32, the movable contacts 34, the metal caps 36, and the conductors 32, 33 are connected in series to the electronic device by surface mounting, and the insulating substrate 31 is installed at a location where the temperature rises excessively when the electronic device is abnormal. Electricity can be supplied to the electronic device through 33 routes.

At the time of excessive temperature rise due to an abnormality of the electronic equipment,
The movable contact 34 made of the shape memory alloy returns to the flat shape which is the memory shape. As a result, the movable contact 34 is separated from the metal cap 36, so that the power supply to the electronic device is stopped. Also, by setting the resistance value of the movable contact 34 appropriately, it is possible to protect the movable contact 34 by returning to the memory shape by self-heating when an overcurrent flows.

When the movable contact 34 is separated from the metal cap 36 and the ambient temperature becomes lower than the shape return temperature of the movable contact 34, permanent deformation of the movable contact 34 causes the permanent contact of the movable contact 34 as shown by a two-dot chain line 34 'in FIG. The return force to the shape acts,
The movable contact 34 comes into pressure contact with the inner surface of the metal cap 34 again. Therefore, since the energization path is formed again, repeated use becomes possible.

[0043]

Modification of Embodiment 4 In the protection element D shown in FIG. 5, a metal base is used in place of the insulating substrate 31 and an insulating member 35 is formed on the entire periphery of the metal base to form a metal base and a metal cap. May be insulated.

[0044]

Fifth Embodiment Next, a protection element E according to a fifth embodiment of the present invention will be described. The protection element E according to the fifth embodiment is configured such that the movable contact is formed by joining a member made of a shape memory alloy to another member different from the member, thereby reducing the resistance of the movable contact or using the other end of the movable contact. The pressing force is increased or the shape changing operation at the time of shape recovery is made steep. FIG. 6 shows a sectional view of a protection element E according to a fifth embodiment of the present invention. In FIG. 6, reference numeral 41 denotes a metal base on which one end of a plate-shaped movable contact 42 is connected and fixed. The movable contact 42 is obtained by connecting a member 43 made of a material different from the shape memory alloy to one surface of a member 43 made of the shape memory alloy. 45
Is an insulating member covering the peripheral portion of the metal base 41, and 46 is a metal cap fixedly sealed on the insulating member 45.
The other end of the movable contact 42 is in pressure contact with the inner surface of the metal cap 46.

Here, in order to reduce the resistance of the movable contact 42, another member 44 made of a material different from the shape memory alloy is joined to a member having a lower resistance than the member 43 made of the shape memory alloy. In order to improve the operating characteristics of the movable contact 42, a member having a thermal expansion coefficient α2 different from the thermal expansion coefficient α1 of the member 43 made of a shape memory alloy may be connected. That is, when, for example, a copper member is used as the member 44 made of another material, it is possible to simultaneously lower the resistance of the movable contact 42 and make the thermal expansion coefficient different. Further, if a shape memory polymer that has already been deformed at an operating temperature or lower is combined as another member 44 made of a material different from the shape memory alloy, + α can be given to the permanent strain. In order to join the member 43 made of a shape memory alloy and another member 44 made of a different material, soldering, conductive paste, resistance welding, plasma welding, ultrasonic welding, holes are made in both, and metal or The method may be appropriately selected from a method of inserting a non-metallic pin and caulking or a method such as painting. Now, when the thermal expansion coefficient α1 of the member 43 made of the shape memory alloy of the movable contact 42 and the thermal expansion coefficient α2 of the copper member 44 have a relationship of α1> α2, the other end of the movable contact 42 is formed by the bimetal effect. The pressing force of the portion on the inner surface of the metal cap 46 increases, and the contact resistance can be reduced.

In the protection element E, the metal base 4
1 and the metal cap 46 are connected in series to the electronic device, and the metal base 41 is installed at a place where the temperature rises when the electronic device is abnormal. Then, the metal base 41-
The electronic device is energized through the path between the movable contact 42 and the metal cap 46. At this time, if a copper member is used as the other member 44, the internal resistance is reduced.

If the temperature rises excessively due to an abnormality of the electronic equipment, the shape returns to the flat plate shape stored in the member 43 made of the shape memory alloy. Here, the other member 44 having a different coefficient of thermal expansion from one side of the member 43 made of a shape memory alloy is bonded to the member 43.
The shape change of the movable contact 42 becomes sharp, and the metal cap 4
Sparks are unlikely to occur when separated from 6.

[0048]

Modification of Embodiment 5 In place of the protection element E, a member 43 made of a shape memory alloy of the movable contact 42 and another member 44 are attached upside down.
Forming a pair of conductors apart from the insulating substrate instead of 1
One end of the movable contact may be connected and fixed to one conductor, and the other end of the movable contact may be pressed into contact with the other conductor.

[0049]

[Embodiment 6] Next, a protection element F according to a sixth embodiment of the present invention will be described.
The protection element F of the sixth embodiment has a structure in which a lower resistance layer than a shape memory alloy is formed on at least the other end of the movable contact. FIG. 7 is a sectional view of a protection element F according to a sixth embodiment of the present invention. In FIG. 7, reference numeral 51 denotes a metal base serving as one of a rectangular or circular conductor, and one end of a movable contact 52 is connected and fixed to the surface thereof. This movable contact 52
Is formed on at least the other end, preferably the entire surface, of the member 53 made of a shape memory alloy.
A low-resistance layer 54 made of a material having a lower resistance than that of the first embodiment is formed. A metal cap 56 is fixedly sealed to the periphery of the metal base 51 via an insulating member 55. The other end of the movable contact 52 is in pressure contact with the inner surface of the metal cap 56. The low resistance layer 54 is made of, for example, Au, Ag, P
Noble metals such as d and Pt, metals such as Cu and Ni, or alloys containing these as main components, and A containing these as main components
It is made of a composite material such as g-CdO, Ag-CuO, or solder, and is formed by a method such as plating, vapor deposition, or sputtering.

According to the protection element F, the low resistance layer 54
As a result, the contact resistance between the movable contact 52 and the metal cap 56 as the other conductor is reduced, and a protection element having a small internal resistance is obtained. In particular, when the low resistance layer 54 is formed on the entire surface of the member 53 made of a shape memory alloy as in the illustrated example, the resistance value of the movable contact 52 becomes small, and a protection element having a smaller internal resistance can be obtained.

[0051]

[Embodiment 7] Next, a protection element G according to a seventh embodiment of the present invention will be described. The protection element G according to the seventh embodiment has an increased contact area between the movable contact and the other conductor. FIG. 8 is a sectional view of a protection element G according to a seventh embodiment of the present invention. In FIG. 8, reference numeral 61 denotes a metal base serving as one of a rectangular or circular conductor,
One end of a movable contact 62 made of a shape memory alloy is connected and fixed to a part thereof by welding or the like. The movable contact 62 is bent twice in the middle. Reference numeral 63 denotes a ring-shaped or frame-shaped insulating member provided on a peripheral portion of the metal base 61, and a metal cap 64 serving as the other conductor is fixedly sealed via the insulating member 63. The other end of the movable contact 62 is in surface contact with the inner surface of the metal cap 64.

In the protection element G according to the seventh embodiment, since the movable contact 62 is in surface contact with the metal cap 64 as the other conductor, the contact area increases, the contact resistance decreases, and the internal resistance decreases. The feature is that a protection element having a small resistance can be obtained.

[0053]

Modification of Embodiment 7 As a modification of the protection element G of the seventh embodiment of FIG. 8, the shape of the movable contact 62 is bent into an S-shape in the middle thereof so that the other end of the movable contact 62 is You may make it contact the metal cap 64 which is the other conductor in a surface contact state. Alternatively, the shape of the movable contact may be kept as it is, and the shape of the lower surface of the top plate portion of the metal cap 64 may be made to match the shape of the movable contact to increase the contact area.

[0054]

[Embodiment 8] Next, a protection element H according to an eighth embodiment of the present invention will be described. The protection element H according to the eighth embodiment has a PTC element integrated therein. FIG. 9 shows a protection element H according to an eighth embodiment of the present invention.
FIG. In FIG. 9, reference numeral 71 denotes a PTC element having a rectangular shape or a circular shape, and a conductor 72 is formed on a part of the surface thereof. One end of a movable contact 73 made of a plate-shaped shape memory alloy is formed on the conductor 72. Is fixedly connected. P
A metal cap 75, which is the other conductor, is fixedly sealed to the periphery of the TC element 71 via an insulating member 74. The other end of the movable contact 73 is
5 is in press contact with the inner surface.

The protection element H of the eighth embodiment is a PTC
The element 71 and the metal cap 75 are connected in series to the electronic device, and the PTC element 71 is installed at a location where the temperature rises when the electronic device is abnormal. Then, the PTC element 7
The electronic device can be energized through the path of 1-movable contact 73-metal cap 75.

When an overcurrent flows through the electronic device due to an abnormality of the electronic device, the PTC element 71 increases its resistance value to suppress and protect the current value. In addition, when the temperature of the electronic device is excessively increased due to an abnormality of the electronic device, the movable contact 63 returns to the flat plate shape stored therein. Since the separation is performed and the current is cut off, the temperature of the electronic device is prevented from further rising excessively, and a fire caused by ignition of the electronic device is also prevented.

[0057]

Ninth Embodiment Next, a protection element I according to a ninth embodiment of the present invention will be described.
In the protection element I of the ninth embodiment, a conductor is led out by forming a through hole in an insulating substrate, and a metal cap is sealed by press fitting. FIG. 10 is a sectional view of a protection element I according to a ninth embodiment of the present invention. In FIG. 10, reference numeral 81 denotes an insulating substrate made of alumina ceramic or the like, whose upper end shoulder is chamfered or curved as shown in the figure for press-fitting sealing described later, and a pair of through holes 82, 83 are formed. These through holes 82 and 83 are filled with a conductive material and
4,85 are formed. One end of a plate-shaped movable contact 86 made of a shape memory alloy is connected and fixed to one conductor 84, and the other end is pressed against the other conductor 85.
Reference numeral 87 denotes a metal cap which is sealed into the insulating substrate 81 by press fitting. For this reason, the metal cap 87 in the present embodiment is different from the metal caps 24, 3 in FIGS.
6, 46, 56, 64 and 75 are formed thinner. Reference numeral 88 denotes a soft metal such as solder that hermetically seals the insulating substrate 81 and the metal cap 87.
The outer peripheral surface of the insulating substrate 81 and the inner peripheral surface of the metal cap 87 are previously attached to one or both of the peripheral edge of the insulating substrate 81 and the inner peripheral surface of the metal cap 87. It fills the gap.

As described above, when the through holes 82 and 83 are formed in the insulating substrate 81 and the conductors 84 and 85 are formed by filling the through holes 82 and 83 with a conductive material, surface mounting becomes possible without the need for leads. . In the above embodiment,
Filling the through holes 82 and 83 with a conductive material
Although the case of forming 4,85 has been described, the conductor may be formed by a conductor made of a metal or an alloy, or by using a conductor made of a metal or an alloy and a conductive material in combination. Also, as in the above embodiment, the metal cap 8
When sealing is performed by press-fitting the insulating film 7 into the insulating substrate 81, no heating is required at the time of sealing, so that not only sealing is easy but also
No thermal strain remains on the movable contact 86.

[0059]

Modified Example 1 of Embodiment 9 In the above embodiment, the case where the other end of the movable contact 86 is simply separated from the other conductor 85 when the movable contact 86 returns to the memorized shape has been described. The other end of 86 may be in pressure contact with the metal cap 87 after being separated from the other conductor 85. By doing so, the conductors 84 and 85 conduct at normal temperature, and after the movable contact 86 returns to the memory shape, the conductor 84 and the metal cap 87 conduct, so-called break contacts and make contacts Is obtained.

[0060]

Modification 2 of Embodiment 9 In the above embodiment, a pair of through holes 82 and 83 are formed in an insulating substrate 81, and a conductive material is filled in the through holes 82 and 83 to form a pair of conductors 8 and 8.
Although the case where 4, 85 are formed has been described, only one of the through holes 82 may be formed, and only the conductor 84 may be formed by filling the through hole 82 with a conductive material. In this way, the lead is unnecessary and surface mounting is possible, and the conductor 84 and the metal cap 87 are in a non-conductive state at normal temperature, and the movable contact 86 returns to the memorized shape at normal temperature. The protection element having a so-called make contact, in which the end portion is brought into press contact with the metal cap 87 and the conductor 84 and the metal cap 87 are brought into a conductive state, is obtained. .

[0061]

Third Modification of the Ninth Embodiment In the second modification of the ninth embodiment, a case has been described where the movable contact 86 is flat at room temperature and is curved by returning to the memorized shape.
6 may be curved at normal temperature and the other end thereof may be in press contact with the metal cap 87, and may be flattened by returning to the memory shape. In that case, a protection element having a so-called break contact is obtained.

The ninth embodiment and its modification 1
The structure in which the through hole is provided and the conductor is led out through the through hole can be adopted when a metal base is used. Of course, when a metal base is used, one of the conductors is also unnecessary because it also serves as the metal base, and the other conductor must of course be led out to the through hole of the metal base through an insulator such as glass or resin. .

Although each of the above embodiments of the present invention has been described with reference to a specific structure, the present invention is not limited to the structure shown in the above embodiment, and does not depart from the spirit of the present invention. It goes without saying that various modifications are possible.

For example, in the protection elements A and B of the first and second embodiments shown in FIGS. 1 and 3, the conductors 2, 3 and 1
Without connecting the leads 4, 5 and 14, 15 to the conductors 2, 13, the conductors 2, 3 and 12, 13 are connected to the end faces of the insulating substrates 1, 11 similarly to the protection element D of the fourth embodiment shown in FIG. It can be extended to the rear surface to form a surface mount type.

Further, at least the other end of the movable contact 52, which is in contact with the other conductor, or the entirety of the noble metal layer such as Au, Ag, Pd, Pt or the like shown in the protection element F of the sixth embodiment of FIG. , Ni, etc. or alloys containing these as main components, Ag-CdO, Ag-C
The structure in which the composite material such as uO or the low resistance layer 54 made of a solder layer is formed is described in the protective elements A to E shown in FIGS.
And the protection elements G to I shown in FIGS. 8 to 10.

Further, the protection element G according to the seventh embodiment shown in FIG.
The configuration of the movable contact 62 in the surface contact state shown in FIG.
May be adopted in the protection elements A to F of the embodiment and the protection elements H to I of the embodiment of FIGS.

Further, the PTC element 71 in the protection element H of the eighth embodiment shown in FIG. 9 is different from the protection elements A to G of the first to seventh embodiments shown in FIGS.
The protection element I of the ninth embodiment shown in FIG.

Furthermore, the insulating substrate on which the pair of conductors are formed and the metal base may be interchanged.

[0069]

According to the present invention, as described above, a pair of conductors,
A movable contact made of a plate-shaped shape memory alloy having one end connected and fixed to the one conductor and the other end pressed against the other conductor; and the movable contact is sealed by a cap. Since the protective element is characterized in that it has a small number of components, it is small, flat and low-profile, and the bottom surface is flat, so that a protective element with excellent thermal response can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a protection element A according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the protection element A according to the first embodiment of the present invention after operation.

FIG. 3 is a sectional view of a protection element B according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a protection element C according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a protection element D according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view of a protection element E according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view of a protection element F according to a sixth embodiment of the present invention.

FIG. 8 is a sectional view of a protection element G according to a seventh embodiment of the present invention.

FIG. 9 is a sectional view of a protection element H according to an eighth embodiment of the present invention.

FIG. 10 is a sectional view of a protection element I according to a ninth embodiment of the present invention.

[Explanation of symbols]

A, B, C, D, E, F, G, H, I Protection element 1, 11, 31, 81 Insulating substrate 2, 3, 12, 13, 32, 33, 84, 85 Conductor 4, 5, 14, 15 Leads 6, 16, 22, 34, 42, 52, 62, 73, 86
Movable contacts 7, 17 Insulating cap 8, 18 Sealing resin 19 Leaf spring for bias 21, 41, 51, 61 One conductor (metal base) 23, 35, 45, 55, 63, 74 Insulating members 24, 36, 46, 56, 64, 75 The other conductor (metal cap) 25 Low melting point alloy 43, 53 Member made of shape memory alloy 44 Member made of material different from shape memory alloy 54 Low resistance layer 71 PTC element 82, 83 Through hole 87 The other conductor (metal cap) (for press-fit sealing)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01H 37/52 H01H 37/52 FG 37/76 37/76 D

Claims (18)

[Claims] A pair of conductors, and a movable contact made of a plate-shaped shape memory alloy having one end connected and fixed to said one conductor and the other end pressed against said other conductor, A protective element, wherein the movable contact is sealed by a cap. 2. A pair of conductors formed apart from each other on an insulating substrate, and a plate-shaped shape memory alloy having one end connected and fixed to said one conductor and the other end pressed against said other conductor. A movable contact and a cap fixedly sealed to the insulating substrate. 3. The other end of the movable contact is provided with a leaf spring for biasing, and the other end of the movable contact is re-established when the ambient temperature falls below the temperature at which the shape memory alloy returns to the memory shape. The protection element according to claim 1, wherein the protection element is urged to press and contact the other conductor. 4. A metal base serving as one conductor, a movable contact made of a plate-shaped shape memory alloy having one end connected and fixed to the metal base, and an insulating member interposed on a peripheral portion of the metal base. And a metal cap serving as the other conductor fixed and sealed, wherein the other end of the movable contact is pressed against the metal cap. 5. The protection element according to claim 4, wherein the other end of the movable contact is connected and fixed to a metal cap serving as the other conductor with a low melting point alloy. 6. A protection element characterized in that the shape of a movable contact made of a shape memory alloy after return is different from the shape at room temperature thereafter. 7. The movable contact returns to the memorized shape at a temperature for returning to the memorized shape, and returns to a position where the movable contact comes into pressure contact with the other conductor due to permanent deformation strain at a lower temperature. Item 7. The protection element according to Item 6. 8. The protection element according to claim 1, wherein the movable contact is formed by joining a member made of a shape memory alloy with another member having a lower resistance than the member. . 9. The protection element according to claim 1, wherein the movable contact is formed by joining a member made of a shape memory alloy to another member having a different coefficient of thermal expansion from the member. 10. The member made of the shape memory alloy and another member are joined by any one selected from soldering, conductive paste, resistance welding, plasma welding, ultrasonic welding, caulking, and painting. The protection element according to claim 8, wherein the protection element is provided. 11. The protection element according to claim 1, wherein said movable contact has a lower resistance layer than a movable contact at at least a contact portion with another conductor. 12. The low-resistance layer is made of Au, Ag, Pd, P
Formed from any metal selected from the group consisting of t, Cu, and Ni, an alloy containing them as a main component, or a Ag-CdO or Ag-CuO composite material containing them as a main component, or a solder material The protection element according to claim 11, wherein the protection element is provided. 13. The protection device according to claim 12, wherein the low resistance layer is formed by any one of plating, vapor deposition, and sputtering. 14. The protection element according to claim 1, wherein the other end of said movable contact is in surface contact with another conductor. 15. The protection element according to claim 1, wherein the movable contact operates at one or both of an excessive rise in ambient temperature and an overcurrent. 16. A PTC element having a plate shape, a movable contact made of a plate-shaped shape memory alloy having one end connected to and fixed to the PTC element, and a sealing member interposed by an insulating member at a peripheral portion of the PTC element. And a metal cap stopped, wherein the other end of the movable contact is connected to the metal cap by pressing contact or a low melting point alloy. 17. At least one through hole is formed in an insulating substrate, one end is connected and fixed to the conductor led through the through hole, and the other end is pressed into contact with the other conductor. A protective element comprising: a movable contact made of a plate-shaped shape memory alloy; and a cap sealed with the insulating substrate. 18. A protection element according to claim 1, wherein said metal cap is sealed by press-fitting into said insulating substrate or metal base.