JP2003162947A - Thermally actuated member and thermal protector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermally actuated member of low electric resistance which inversely operates repeatedly without degrading an initial operation stroke even if it is worked into a very small thermally actuated element, and to provide a thermal protector which is smaller, with a longer operation life. <P>SOLUTION: The thermally actuated member has a laminate of a high thermal-expansion metal layer and a low thermal-expansion metal layer and a coat of a high conductive thin film of high conductivity, comprising at least one element over the surface of the high thermal-expansion metal layer side and/or low thermal-expansion metal layer side. The thickness of the high conductive thin film is preferred to be 1.5-10 μm. A thermal protector is so configured that a movable contact provided to one end or both ends of the thermally actuated element formed with the thermally actuated member comes away from a fixed contact due to deformation of the thermal actuated element in overheating. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat responsive member having conductivity and a thermal protector using the heat responsive member.

[0002]

2. Description of the Related Art A heat-responsive member having conductivity is widely used as a heat-responsive element of a thermal protector that shuts off a circuit when an overcurrent flows in the circuit or when the circuit overheats, and other heat-responsive elements. The thermal protector is generally used as a protection component that interrupts a circuit against overcurrent or overheat of a secondary battery used in various motors and devices. For example, thermal protectors for secondary batteries such as mobile phones and notebook computers, thermal protectors for small motors, motors for automobiles, thermal protectors for DC circuits for protecting chargers, fans for air conditioners, electric washing machines, etc. It is a thermal protector for AC circuits used for general purpose motor protection.

A thermal protector using a heat responsive element having conductivity has a structure as shown in FIG. 8, for example. This figure is a sectional view of the thermal protector.
A fixed contact 2a for connecting to a terminal 20a extending to the outside of the case 1 is installed at one end of the case 1 in which the main body 10 is sealed with a lid 11. In the case 1, a thermo-responsive element (bimetal) 4 which is formed in a substantially mountain shape or a convex spherical shape and which reverses at a predetermined operating temperature is accommodated. The fixed contact 2 is provided at the tip of the thermoresponsive element 4.
A movable contact 4a that is in contact with a is provided, and the base end portion of the thermoresponsive element 4 is joined to the other terminal 40a that extends outward from the other end portion side of the case 1. The thermal protector shown in FIG. 8 is installed at a required position in a state where the terminals 20a and 40a are connected to other terminals such as a battery and an electronic board (not shown). In the installed state, when the temperature of the installation site rises due to overcurrent or overheating and the temperature reaches or exceeds the operating temperature of the thermoresponsive element 4, the thermoresponsive element 4
However, due to the snap action, each movable contact 4a is reversed to the state in which it is separated from the corresponding fixed contact 2a, and the circuit operates at that portion.

Thermally responsive element 4 of a conventional thermal protector
The heat-responsive member that constitutes the
As enlarged and shown in FIG. 9, a member in which a high-conductivity layer 42 made of a metal element having a high conductivity such as Cu is sandwiched between a high-thermal-expansion metal layer 40 and a low-thermal-expansion metal layer 41, and laminated. Met.

[0005]

With the recent miniaturization and higher performance of electric devices, not only the thermal protectors used therein but also the thermal responsive elements of the thermal protectors are required to be further miniaturized. There is. The inventors
A conventional thermo-responsive member as shown in FIG. 9 is molded into a convex spherical shape by forming a micro-miniature member having, for example, a length of 4 mm, a width of 3 mm and a thickness of 0.07 mm to form a thermo-responsive element, and the thermo-responsive element is operated. The state of heat fluctuation including snap action was observed by heating above the temperature. As a result, a snap operation (reverse operation) necessary for the operation of the thermal protector (reversal operation) was recognized at the first time, but from the second time, the high thermal conductive layer 42 such as copper, which is the intermediate layer, was detected. Due to plastic deformation and slippage of the interface between the high thermal conductive layer 42 and the high thermal expansion metal layer 40, the overall convex spherical shape of the thermal responsive element is deformed and the snap action necessary for operating the thermal protector tends not to occur. showed that.

An object of the present invention is to provide a thermo-responsive member which can be accurately and repeatedly reversed many times without reducing the initial operation stroke even when it is processed into a very small thermo-responsive element having a small electric resistance as described above. To provide. It is another object of the present invention to provide a thermal protector that can operate repeatedly and accurately even when manufactured in a small size.

[0007]

The heat responsive member according to the present invention is configured as follows in order to solve the above problems. That is, the heat responsive member according to claim 1 is
A high thermal expansion metal layer and a low thermal expansion metal layer are laminated, and a high conductivity thin film made of at least one element having high conductivity is deposited on the surface of the high thermal expansion metal layer side and / or the low thermal expansion metal layer side. Is characterized by.

The heat responsive member according to a second aspect is the first aspect.
In the heat responsive member of, the high-conductivity thin film is Au, Ag, C
It is characterized by being one or more elements selected from u, Al, Ni, Sn, Rh or Ru.

According to a third aspect of the present invention, there is provided the heat responsive member according to the first aspect.
Alternatively, in the heat responsive member of No. 2, the high thermal expansion metal layer is Mn-
It is a Ni-Cu alloy or a Ni-Cr-Fe alloy, and the low thermal expansion metal layer is a Fe-Ni alloy.

A heat responsive member according to a fourth aspect is the first aspect.
The heat responsive member according to any one of items 1 to 3 is characterized in that the high-conductivity thin film has a thickness of 1.5 to 10 μm.

The thermal protector according to claim 5 is
In order to solve the above-mentioned problems, the movable contact provided at one end or both ends of the thermoresponsive element formed by the thermoresponsive member according to any one of claims 1 to 4 is deformed by the deformation of the thermoresponsive element when overheated. It is characterized in that it is configured to separate from the fixed contact.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a heat responsive member and a thermal protector according to the present invention will be described with reference to FIGS. Embodiment of heat responsive member FIG. 1 is a plan view of a heat responsive element for a thermal protector processed by the heat responsive member of this embodiment, and FIG. 2 is a partially enlarged sectional view of the heat responsive member constituting the heat responsive element of FIG. It is a figure.

The heat responsive element 3 processed by the heat responsive member of this embodiment has a length L = 4.1 mm and a width w = 1.8.
mm, wall thickness t = 0.07mm, 80 ℃
It is formed in a mountain shape or a convex spherical shape (or a convex arc shape) as a whole so that it can be reversed in the front-rear direction. Movable contacts 3a, 3a made of, for example, a silver alloy are welded to the back surface of the portion of the thermal responsive element 3 that projects at both ends in the longitudinal direction.

As shown in FIG. 2, the heat responsive member is Mn-Ni-.
High thermal expansion metal layer 30 made of Cu alloy or Ni-Cr-Fe alloy and low thermal expansion metal layer 3 made of Fe-Ni alloy.
1 is laminated with, for example, a clad to form a high thermal expansion metal layer 3
A high-conductivity thin film 32 made of, for example, Cu or other high-conductivity element and having a thickness of about 1.5 to 10 μm is adhered to the 0-side surface. The high-conductivity thin film 32 is made of Cu, Au,
Ag, Al, Ni, Sn, Rh, or Ru can be used, and a plurality of these elements can be selected and used instead of a single element. The high-conductivity thin film 32 is fixed by, for example, a wet plating method, a vapor deposition method, a sputtering method, or the like.

The high-conductivity thin film 32 can be applied to the surface of the low thermal expansion metal layer 31 side as shown in FIG. 3 instead of the surface of the high thermal expansion metal layer 30 side as shown in FIG. As in No. 4, it may be adhered to the surfaces of the high thermal expansion metal layer 30 side and the low thermal expansion metal layer 31 side.

Embodiment of Thermal Protector FIG. 5 is a sectional view of a thermal protector using the heat responsive element of FIG. 1, and FIG. 6 is a sectional view of the thermal protector of FIG. Case 1 is made of, for example, polyphenylene sulfide (PPS), liquid crystal polymer (LC
P), polybutylene terephthalate (PBT) and other resins having excellent heat resistance are molded and are composed of a main body 10 and a lid 11 sealing the main body 10. The main body 10 of the case 1 includes a convex seat 12 at the center of the bottom.
Is formed, and fixed contacts 2 and 2 are provided at both ends of the bottom, and these fixed contacts 2 and 2 are connected to the respective terminals 20 and 20 extending outside the case 1. A thermoresponsive element 3 configured as shown in FIG. 1 is housed in the main body 10, and a central portion of the upper surface of the thermoresponsive element 3 is connected to a convex seat portion 13 formed in a central portion of an inner top surface of the lid 11. The movable contacts 3a, 3a at both ends thereof are in contact with the corresponding fixed contacts 2, 2, respectively. The main body 10 has fixed contacts 2,
2. After insert molding, for example, with these parts so that the terminals 20, 20 are embedded, the lid 11 is joined to the main body 10 by an ultrasonic welding method or the like.

In FIG. 5, the movable contact 3 is provided by the thermoresponsive element 3.
It is shown that a and 3a are in contact with the corresponding fixed contacts 2 and 2 pressed against each other, and a current normally flows between the contacts. When an abnormal current flows between the contacts or the temperature in the case 1 rises due to other causes and the temperature in the case 1 reaches the operating temperature of the thermal response element 3 or higher, the thermal response element 3 snaps. The reverse operation is performed so as to present a concave spherical shape upward. The heat responsive element 3 is moved by the reversing operation as shown in FIG.
Are separated from the corresponding fixed contacts 2 to cut off the current between the contacts.

The thermal responsive element 3 comprising the thermal responsive member of the above-described embodiment has the high thermal expansion metal layer 30 and the low thermal expansion metal layer 31 laminated, and the high thermal expansion metal layer 30 side and / or the low thermal expansion metal layer 31 side. A highly conductive thin film 32 made of at least one element having a high conductivity is deposited on the surface. Since the influence of the plastic deformation of the high-conductivity thin film 32 is extremely smaller than that of the conventional one, even if it is formed into a very small size as described above, the initial working stroke should be reduced by the temperature above the predetermined working temperature. It is possible to repeat the reversing operation accurately without. Further, the thermal protector according to the above-described embodiment operates with good performance and repeatability even when manufactured in a very small size.

In the above embodiment of the heat responsive member, the thickness of the high-conductivity thin film 32 is preferably 1.5 to 10 μm. The reason is that if the thickness of the high-conductivity thin film 32 is less than 1.5 μm, the electric resistance of the heat responsive member becomes large, which is not preferable. The effect of plastic deformation on the entire member becomes large, and when it is molded as a thermal response element of a small thermal protector and repeatedly operated as described above, the reversal operation becomes slow and the contact is damaged and its life is shortened. It depends.

Other Embodiments In the thermal protector according to the present invention, a fixed contact is provided at one end of the inner bottom of the case, the fixed contact is connected to a terminal extending outside the case, and one end is connected to the fixed contact. A so-called configuration as shown in FIG. 8 in which a thermoresponsive element provided with a movable contact to be contacted is housed in a case and the other end of the thermoresponsive element is connected to another terminal extending outside the case You can

EXAMPLE A high thermal expansion metal layer 30 made of an Mn-Ni-Cu alloy,
A high-conductivity thin film 3 made of Cu is clad with a low thermal expansion metal layer 31 made of an Fe-Ni alloy, and is formed on one surface of the high thermal expansion metal layer 30 side and the low thermal expansion metal layer 31 side.
2 by wet plating method 0 (thing not to be adhered) to 15
Samples of several heat responsive members deposited up to μm were manufactured. 1 and 5 using each of these samples.
Mold the thermo-responsive element 3 in the form as shown below (length L = 4.1 m
m, width w = 1.8 mm, wall thickness t = 0.07 mm), and movable contacts 3a, 3a of Cu alloy (Ni: alloy containing 10 mass%) were welded to both ends. Each of these thermal actuators was incorporated into a thermal protector having a configuration as shown in FIG. 5, and the electric resistance between the terminals 20 and 20 was measured by the four-terminal method. The material of each fixed contact 2 was the same as that of the movable contact 3a. The results are shown in FIG. 7. As shown in FIG. 7, the sample in which the high-conductivity thin film 32 was not deposited had an electric resistance of 30 mΩ or more, but the sample in which the thin film 32 had a thickness of 1.5 μm or more showed an electric resistance. Resistance is 1
It was 5 mΩ or less. In particular, the sample in which the high-conductivity thin film 32 had a thickness of 2 μm or more showed a small electric resistance of 10 mΩ or less.

In addition, a current (DC 6
V-5A) was made to flow, the contact life was tested, and the operating state of the thermoresponsive element was observed using a transmission X-ray apparatus. As a result, in the thermal protector using the thermo-responsive element based on the sample in which the high-conductivity thin film 32 has a thickness of 1.5 to 10 μm, those thermo-responsive elements are repeatedly inverted correctly many times to break the circuit 10,000 times or more. We were able to. On the other hand, in the thermal protector using the heat responsive element made of the sample in which the high-conductivity thin film 32 exceeds 10 μm, the contact separation operation of the movable contacts 3a, 3a with respect to the fixed contacts 2, 2 becomes slow with the passage of time, and the contact damage is prevented. The shortening of the contact life was recognized due to intensification. From the above results, in the heat responsive member used as the heat responsive element of the thermal protector, the thickness of the high-conductivity thin film 32 is 1.5 to 10 μm because of the relationship between the electrical resistance value and the contact life. preferable. The high thermal expansion metal layer 30 side and the low thermal expansion metal layer 3
The same test was performed on the same sample with the high-conductivity thin film deposited on both surfaces on the 1 side, and the same result was obtained.

[0023]

According to the heat responsive member of the present invention, the high thermal expansion metal layer and the low thermal expansion metal layer are laminated, and the high thermal expansion metal layer side and / or the low thermal expansion metal layer side is formed. Since the high-conductivity thin film consisting of at least one element with high conductivity is deposited on the surface of the, and the influence of plastic deformation of the high-conductivity thin film is much smaller than the conventional one, the thermal response element can be made very small. Even in the case of molding, the reversing operation can be accurately repeated many times without reducing the initial operation stroke due to the temperature higher than the predetermined operation temperature.

According to the heat responsive member of the invention of claim 4, the high-conductivity thin film has a thickness of 1.5 to 10 μm,
Since it has a small electric resistance and repeats stable and accurate operation 10,000 times or more, it is particularly suitable for use as a thermal response element of a thermal protector.

According to the thermal protector of the fifth aspect of the invention, since it operates by the thermal responsive element formed by the thermal responsive member of any one of the first to fourth aspects, it has good performance even when manufactured in a small size. It works correctly and repeatedly.

[Brief description of drawings]

FIG. 1 is a plan view of a heat responsive element for a thermal protector including a heat responsive member according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of a heat responsive member forming the heat responsive element of FIG.

FIG. 3 is a partially enlarged cross-sectional view showing another embodiment of the heat responsive member according to the present invention.

FIG. 4 is a partial enlarged cross-sectional view showing still another embodiment of the heat responsive member according to the present invention.

FIG. 5 is a sectional view of a thermal protector according to an embodiment of the present invention.

6 is a cross-sectional view of a movable contact of the thermal protector of FIG. 5 in a state of being separated from a fixed contact.

FIG. 7 is a graph showing the relationship between the thickness and the electrical resistance of the high-conductivity thin film of the heat responsive member according to the present invention.

FIG. 8 is a cross-sectional view of a thermal protector using a conventional thermal response element including a thermal response member.

9 is a partially enlarged cross-sectional view of a heat responsive element used in the thermal protector of FIG.

[Explanation of symbols]

1 case 10 body 11 lid 12, 13 convex seat 2,2a fixed contact 20, 20a, 40a terminals 3,4 Thermal response element 3a, 4a movable contact 30,40 High thermal expansion metal layer 31,41 Low thermal expansion metal layer 32 High conductivity thin film 42 High conductivity layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Nagai             528-5 Kiyotaki Shinhosoo, Nikko City, Tochigi Prefecture             Misaki Metal Industry Co., Ltd. F term (reference) 5G041 AA03 AA13 BB06 BB08 CA07                       CA13 CC01 CD10 DA02 DB01                       DC03

Claims (5)

[Claims] 1. A high-thermal-expansion metal layer and a low-thermal-expansion metal layer are laminated, and a high-conductivity thin film made of at least one element having high conductivity is coated on the surface of the high-heat expansion metal layer side and / or the low-heat expansion metal layer side. A heat responsive member characterized by being worn. 2. The high-conductivity thin film is Au, Ag, Cu, A
The heat responsive member according to claim 1, wherein the heat responsive member is one or more elements selected from 1, Ni, Sn, Rh, or Ru. 3. The high thermal expansion metal layer is a Mn—Ni—Cu alloy or a Ni—Cr—Fe alloy, and the low thermal expansion metal layer is F.
It is an e-Ni alloy, It is characterized by the above-mentioned.
The heat responsive member according to. 4. The heat responsive member according to claim 1, wherein the high-conductivity thin film has a thickness of 1.5 to 10 μm. 5. A movable contact provided at one end or both ends of a thermoresponsive element formed of the thermoresponsive member according to claim 1, is fixed by deformation of the thermoresponsive element when overheated. A thermal protector characterized by being configured to separate from a contact.