JP2005129471A - Thermal protector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve further downsizing or simplifying of an assembly process of a thermal protector. <P>SOLUTION: The thermal protector is equipped with a fixation piece having a fixed contact point, a movable piece contacting a movable contact point provided at a tip part to the fixed contact point by a spring action, a heat responding element operating the movable piece to have the movable contact point separated from the fixed contact point under a given operation temperature, a PTC element connected with the fixation piece and a flat insulation case storing the fixation piece, the fixed contact point, the movable contact point, the movable piece, the heat responding element and the PTC element. The fixation piece and the movable piece have terminal parts each appearing outside the case, the PTC element is placed between mutually opposing surfaces of the fixation piece and the movable piece, and the heat responding element is formed on an inner bottom surface of a case body in a covered condition on an upper surface of the PTC element, positioned by a positioning wall to which a whole part or one part of an outer peripheral edge part of the heat responding element is contacted or adjacent, and also, arranged in a condition in which one part of one surface is contacted to the PTC element at reversing while the other surface is in contact with the movable piece. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thermal protector having a structure in which a movable contact is separated from a fixed contact and a circuit is shut off by a reversal action of a thermally responsive element when a predetermined operating temperature is reached.

This type of thermal protector is generally used as a protective component that interrupts the circuit against overcurrent and overheating of secondary batteries used in various motors and various devices.
Patent Document 1 described later discloses a thermal protector (safety device) as shown in FIG.
In FIG. 9, reference numeral 1 denotes an insulating case in which a lid 11 is tightly joined to a case main body 10. In this case 1, a fixed piece 20 having a fixed contact 2 and a movable contact 3 at the tip are spring-actuated. A movable piece 30 that is in contact with the fixed contact 2 by a thermal activation element (bimetal plate) 4 that operates the movable piece 30 in a direction to move the movable piece 30 away from the fixed contact 2 at a predetermined operating temperature; A PTC element 5 such as a positive temperature coefficient thermistor for connecting the movable piece 30 is enclosed.
The fixed piece 20 is formed integrally with the case body 10, and the movable piece 30 is formed integrally with the lid body 11. The movable piece 30 and the fixed piece 20 are arranged so as to face each other in the case 1 and have terminal portions 21 and 31 extending to the outside of the case 1, respectively.
An accommodation hole 102 is formed in an end portion of the inner bottom portion of the case body 10 away from the fixed contact 2 so that a part of the fixed piece 20 is exposed to the inside, and the disk-like PTC element 5 is accommodated in this case. The electrode portion on the lower surface side is accommodated in the hole 102 and is in contact with the three protruding pedestals 22 formed at intervals of about 120 degrees on the fixed piece 20. On the other hand, a protrusion 34 is formed on the movable piece 30 in the direction of the PTC element 5, and the protrusion 34 is in contact with the electrode portion on the upper surface side of the PTC element 5.
The thermally responsive element 4 formed in a convex spherical shape or a convex arc shape toward the top is placed on a convex pedestal 103 formed on the inner bottom of the case body 10, and the movable contact 3 and the PTC element 5 are placed. In contact with the lower surface of the movable piece 30.

The thermal protector shown in FIG. 9 is installed at a required location of equipment in a state where it is connected to a wiring electrode on a circuit board or the like so that current flows from the terminal portion 21 side to the terminal portion 31 side.
In a normal state without overcurrent or overheating, a current flows between the contacts 2 and 3, so that no current substantially flows through the PTC element having a large electric resistance, and the PTC element does not generate heat. On the other hand, when the temperature in the case 1 exceeds a predetermined operating temperature due to overcurrent or overheating, the thermal responsive element 4 is inverted so as to warp into a concave spherical surface, and the movable piece 30 is pushed upward by its snap action to move the movable contact. By separating 3 from the fixed contact 2, the current between the contacts is interrupted, and the devices are protected from overcurrent or overheating. When the current between the contacts is interrupted, the voltage between the terminal portions 21 and 31 is applied to the PTC element 5, and the element 5 is energized → heat generation → increase in electric resistance → decrease in energization → decrease in temperature → decrease in electric resistance → Since it functions as a constant temperature heating element by the action of increasing energization amount → heating, the current interruption state between the contacts 2 and 3 is maintained.

The thermal protector can be manufactured in a thin shape. However, since the operating portion of the movable piece 30 (installation portion of the thermally responsive element 4) and the installation portion of the PTC element are arranged side by side, the length of the thermal protector (see FIG. The amount of 9 in the left-right direction is large, and there is a problem of reducing the space efficiency in the equipment.
JP 11-297174 A JP 7-45169 A

  The problem to be solved by the present invention lies in further miniaturization of the thermal protector and further simplification of the assembly process, and an object of the present invention is to provide a thermal protector that can solve this problem.

In order to solve the above problems, a first thermal protector according to the present invention includes a fixed piece having a fixed contact, a movable piece for bringing the movable contact at the tip portion into contact with the fixed contact by a spring action, and a predetermined operating temperature. And the PTC element connected to the fixed piece, the fixed piece, the fixed contact, the movable contact, the movable, and the PTC element connected to the fixed piece so that the movable contact is separated from the fixed contact. An insulating flat case containing a piece, a thermally responsive element and a PTC element, and comprising a case main body and a lid joined to the main body; and an exterior of the case which is continuously or connected integrally with the fixed piece And a terminal portion that is continuous with or connected to the movable piece and appears outside the case, wherein the PTC element is between the opposing surfaces of the fixed piece and the movable piece. The thermal responsive element is positioned by a positioning wall formed on the inner bottom surface of the case body in a state where the thermal responsive element covers the upper surface of the PTC element, and all or a part of the outer peripheral edge of the thermal responsive element is in contact with or close to it. The main feature is that a part of one surface is in contact with the PTC element and the other surface is in contact with the movable piece during reversal.
In order to solve the above-mentioned problem, the second thermal protector according to the present invention makes a fixed piece having a fixed contact and a movable contact at a tip end contact the fixed contact by a spring action, and at a predetermined operating temperature. Accommodates a movable piece composed of a thermally responsive element that reverses so that the movable contact is separated from the fixed contact, a PTC element connected to the fixed piece, and the fixed piece, the fixed contact, the movable contact, the movable piece, and the PTC element. And an insulating flat case composed of a case main body and a lid joined to the main body, a terminal portion that is continuous with or connected to the fixed piece and appears outside the case, and the movable A terminal portion that is connected to a piece and appears outside the case, wherein the PTC element is located between the opposing surfaces of the fixed piece and the movable piece, and the movable piece has a reversing portion during operation. PT That are arranged in a state in contact with the device being mainly characterized.

In the first thermal protector according to the present invention, the PTC element is located between the opposing surfaces of the fixed piece and the movable piece, and the thermally responsive element covers the upper surface of the PTC element. All or a part of the outer peripheral edge of the thermally responsive element formed on the bottom surface is positioned by a positioning wall that comes into contact with or close to it, and a part of one surface contacts the PTC element during reversal and the other surface is the movable piece Therefore, the whole can be further downsized, and the manufacturing process is further simplified.
In the second thermal protector according to the present invention, the PTC element is positioned between the opposing surfaces of the fixed piece and the movable piece, and the movable piece is disposed in a state where the reversing portion contacts the PTC element during operation. Therefore, the whole can be further reduced in size and the manufacturing process is further simplified.

Hereinafter, an embodiment of a thermal protector according to the present invention will be specifically described with reference to FIGS.
First Embodiment FIG. 1 is an exploded sectional view of a thermal protector (corresponding to claim 1) according to a first embodiment of the present invention, and FIG. 2 is a sectional view in a normal state of the thermal protector of the first embodiment after assembly. FIG. 3 is a cross-sectional view of the thermal protector shown in FIG.

A flat insulating case 1 having a substantially rectangular parallelepiped shape as a whole is composed of a case main body 10 and a lid body 11 joined to the main body 10 in a sealed manner.
In the case 1, a plate-shaped fixed piece 20 having a fixed contact 2 connected or clad on the upper surface of one end portion and a plate-shaped fixed contact 2 brought into contact with the fixed contact 2 by a spring action. The movable piece 30 is in contact with the fixed piece 20 and the thermally responsive element (trimetal or bimetal) 4 that operates the movable piece 30 so as to separate the movable contact 3 from the fixed contact 2 by reversing at a predetermined operating temperature. And the connected PTC element 5 are sealed.

The fixed piece 20 is embedded in the bottom portion of the case body 10, and one end portion thereof is integrally formed with a terminal portion 21 extending from the one end portion of the main body 10. The terminal portion 21 can be implemented without being integrated with the fixed piece 20.
A housing hole 102 that substantially matches the planar contour of the PTC element is formed in the inner bottom portion of the main body 10 so that a part of the fixed piece 20 is exposed upward, and in the outer circumferential direction of the housing hole 102, the thermally responsive element 4. The positioning wall 101 having a planar shape that is similar to and slightly larger than the planar shape is formed to be continuous. Since the positioning wall 101 is used for positioning the thermally responsive element 4, when the thermally responsive element 4 is placed on the PTC element 5 as described later, the thermally responsive element 4 is not less than a predetermined amount in the horizontal direction. As long as they are positioned so as not to deviate, it is not necessary to be continuous, and it is sufficient if they are in contact with or close to at least three locations on the outer peripheral edge (planar contour) of the thermal response element 4.
A terminal portion 31 is embedded in the case body 10 so as to protrude from the end opposite to the terminal portion 21, and the joint portion 31 a inside the case 1 of the terminal portion 31 is exposed on the upper surface. .

  The square-shaped heat-responsive element 4 having a rounded corner is usually shaped to have a slightly convex spherical shape or a convex arc shape upward, so that it does not buffer with other members during reversal operation. It is designed to have as large a plane area as possible.

  The movable piece 30 formed in a rectangular shape in plan view and having a slightly convex arc shape is provided with the movable contact 3 downwardly attached to the tip, and small downward projections 32, 32 are formed at positions closer to the center than both ends. Has been.

  A metal plate 6 is embedded in the lid 11 of the case 1 mainly for reinforcement. One end of the metal plate 6 extends from one end of the lid 11 to the outside.

In this embodiment, the fixed piece 20 including the fixed contact 2 and the terminal portion 31 are integrated with the main body 10 by insert molding so as to be embedded in the case main body 10 made of an insulating resin.
The metal plate 6 is integrated with the lid body 11 by insert molding with the lid body 11 made of an insulating resin.
In order to manufacture the thermal protector, after forming the main body 10 and the lid body 11 so that the respective parts are integrated as described above, the disc-shaped PTC element 5 is accommodated in the accommodation hole 102, and the The lower surface side electrode part is brought into contact with the fixed piece 20. Next, the thermally responsive element 4 is placed on the PTC element 5 and placed so that the outer peripheral edge of the thermally responsive element 4 is in contact with or close to the positioning wall 101, and the base end of the movable piece 30 is a terminal. The lid body 11 is tightly joined to the main body 10 by ultrasonic joining.

The case body 10 and the lid body 11 are molded from polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT) or other resin having excellent heat resistance. In particular, when a battery pack is manufactured by integrating with a secondary battery by insert molding or the like, it is preferable to use a liquid crystal polymer having a heat resistance of 200 ° C. or higher.
The material of the fixed piece 20 and the terminal portion 21 is preferably copper, but a conductive material such as phosphor bronze, Cu—Ti alloy, Cu—Be alloy, white, brass, Cu—Ni—Si alloy can be used.
The material of the movable piece 30 is preferably a Cu—Be alloy, but a spring material having conductivity such as phosphor bronze, Cu—Ti alloy, white, brass, Cu—Ni—Si alloy can be used.
The material of the fixed contact 2 and the movable contact 3 is preferably a nickel-silver alloy, and is particularly preferably a silver alloy containing, for example, 10 mass% nickel. However, a contact material such as a copper-silver alloy, a gold-silver alloy, a carbon-silver alloy, or a tungsten-silver alloy can be used for these parts. The contact points 2 and 3 may be joined to the fixed piece 20 or the movable piece 30 by any means such as cladding, plating, caulking, or other specific means.
As the thermally responsive element 4, for example, a laminate of a high thermal expansion metal material made of Cu—Ni—Mn alloy and a low thermal expansion metal material made of Ni—Fe alloy is used.

The thermal protector of this embodiment is used by being set so as to be connected to, for example, an electric circuit of a mobile phone in an integrated state with a secondary battery.
When current is flowing normally in the set state in such an apparatus, the movable contact 3 is in contact with the fixed contact 2 while being pressed by the elasticity of the movable piece 30 as shown in FIG.
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 exceeds the operating temperature of the thermal actuator 4, the thermal actuator 4 is snapped by a snap action. As shown in FIG. By reversing the thermal responsive element 4 in this way, the tip end side of the movable piece 30 is pushed upward to move the movable contact 3 away from the fixed contact 2 as shown in FIG. To do. Since both ends of the thermal responsive element 4 come into contact with the downward projections 32, 32 of the movable piece 30 in the process of the reversing operation, the reversing operation is quick.
When the thermally responsive element 4 is reversed, the reversing part of the thermally responsive element 4 presses the PTC element 5 against the fixed piece 20 with a predetermined pressure, the fixed piece 20 and the movable piece 30 are electrically connected, and a current flows in the circuit. Flows, the PTC element 5 generates heat at a constant temperature and continues to interrupt the current between the contacts 2 and 3.

The thermal protector of the above embodiment is firstly arranged so that the PTC element 5 is not aligned with the thermal responsive element 4 in the horizontal direction so as to overlap between the fixed piece 20 and the movable piece 30. Can be realized.
Secondly, the heat-responsive element 4 is provided so as to cover the PTC element 5 which is a constant temperature heating element, and the heat of the PTC element 5 is easily transmitted to the heat-responsive element 4, so that the set temperature of the PTC element is kept low. Can do.
Third, the thermally responsive element 4 is easily and accurately positioned by the positioning wall 101.

Second Embodiment FIG. 4 is a cross-sectional view showing a second embodiment (corresponding to claims 1 and 3) of the thermal protector according to the present invention, and FIG. 5 is a state in which the current between the contacts of the thermal protector of FIG. FIG. 6 is a cross-sectional view, and FIG. 6 is a plan view showing the relationship between the case main body and the thermal actuator in the thermal protector of FIG.

In the thermal protector of the second embodiment, the movable piece 30 and the metal plate 6 are integrally formed on the lid 11 by insert molding. The metal plate 6 also serves as a top plate of the lid 11 and has conductivity, and can be used as an electrode when one end thereof is connected to the movable piece 30. On the lid 11, a downward projection 110 is formed on the metal plate 6, and when the thermally responsive element 4 is inverted and the movable piece 30 floats as shown in FIG. When the end portion of the PTC element 5 abuts against the protrusion 110, the thermally responsive element 4 presses the PTC element 5 more strongly against the fixed piece 20.
In the movable piece 30, a base end portion extending outward from the lid body 11 constitutes a terminal portion 31. In the case 1, the bent portion is bent downward at the opposite end of the mounting position of the movable contact 3. 33 is formed, and a downward projection 32 is formed near the movable contact 3. The bending portion 33 of the movable piece 30 has an effect of suppressing the movement of the thermally responsive element 4 and the PTC element 5 due to vibration or the like and stabilizing their positions. The terminal portion 31 side of the movable piece 30 is embedded in the lid 11, and the downward convex portion 112 formed at the end of the inner surface of the lid 11 regulates the end of the thermally responsive element 4. It has become.
Projecting pedestals 22 are formed on the upper surface of the fixing piece 20 forming the inner bottom surface of the accommodation hole 102 at an interval of 90 degrees from the center, and the lower surface side electrode portion of the PTC element 5 is stably attached to each protruding pedestal 22. It is comprised so that it may contact.

In the thermal protector of the second embodiment, the thermally responsive element 4 is restricted from moving in the horizontal direction by the positioning wall 101 formed on the inner bottom of the case body 10, and the bent portion 33, the protrusion 32, and the downward convex portion 112. And the vertical movement is restricted.
When the temperature in the case 1 exceeds the operating temperature of the thermal responsive element 4 and the thermal responsive element 4 is reversed as shown in FIG. 5, the tip of the thermal responsive element 4 comes into contact with the protrusion 32 of the movable piece 30. The PTC element 5 is pressed against the fixed piece 20 while the end is in contact with the convex 112 of the lid 11.
Other configurations, operations, and effects of the thermal protector of the second embodiment are the same as those of the thermal protector of the first embodiment, and thus their description is omitted.

Third Embodiment FIG. 7 is a cross-sectional view showing a third embodiment (corresponding to claim 1) of the thermal protector according to the present invention.
The thermal protector according to the third embodiment forms a downward restricting convex portion 111 substantially at the center of the metal plate 6 that is integrally inserted into the lid 11 of the case, and this restricting convex portion 111 is used as the operating portion of the movable piece 30. The movable piece 30 is configured to be pressed downward by being brought into contact with the ring, and fatigue of the welded portion between the movable piece 30 and the terminal portion 31 due to repeated operation is reduced.
On the metal plate 6 that constitutes a part of the lid 11, a downward projection 110 is formed, against which the tip of the movable piece 30 abuts during operation.
Other configurations, operations, and effects of the thermal protector of the third embodiment are substantially the same as those of the thermal protector of the first embodiment, and thus description thereof is omitted.

Fourth Embodiment FIG. 8 is a cross-sectional view showing a fourth embodiment (corresponding to claim 2) of the thermal protector according to the present invention.
In the thermal protector of the fourth embodiment, the movable piece 30 also serves as the thermally responsive element 4, and the base end portion of the movable piece 30 is joined to the terminal portion 31. The PTC element 5 is located between the opposing surfaces of the fixed piece 20 and the movable piece 30, and the temperature in the case 1 exceeds the operating temperature of the movable piece 30 that also serves as the thermally responsive element 4. When a reverse operation is performed, a part of the lower surface (reversal center portion) of the movable piece 30 comes into contact with the upper surface of the PTC element 5 in a pressed state.
The other configurations, operations, and effects of the fourth embodiment are substantially the same as those of the thermal protector of the second embodiment, and thus description thereof is omitted.

1 is an exploded cross-sectional view of a thermal protector (corresponding to claim 1) according to a first embodiment of the present invention. It is sectional drawing in the normal state of the thermal protector of 1st Embodiment after an assembly. It is sectional drawing of the state by which the electric current between the contacts of the thermal protector of FIG. 2 was interrupted | blocked. It is sectional drawing which shows 2nd Embodiment (corresponding to Claim 1) of the thermal protector which concerns on this invention. It is sectional drawing of the state by which the electric current between the contacts of the thermal protector of FIG. 4 was interrupted | blocked. It is a top view which shows the relationship between the case main body and thermal response element in the thermal protector of FIG. It is sectional drawing which shows 3rd Embodiment (corresponding to Claim 1) of the thermal protector which concerns on this invention. It is sectional drawing which shows 4th Embodiment (corresponding to Claim 2) of the thermal protector which concerns on this invention. It is sectional drawing of the thermal protector currently disclosed by patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 10 Case main body 101 Positioning wall 102 Accommodating hole 11 Cover body 110 Protrusion 111 Restriction convex part 112 Convex part 2 Fixed contact 20 Fixed piece 21 Terminal part 22 Protrusion base 3 Movable contact 30 Movable piece 31 Terminal part 4 Thermally-responsive element 5 PTC element

Claims (7)

A fixed piece (20) having a fixed contact (2), a movable piece (30) for bringing the movable contact (3) at the tip portion into contact with the fixed contact (2) by a spring action, and reversing at a predetermined operating temperature. Accordingly, a thermally responsive element (4) that operates the movable piece (3) so that the movable contact (3) is separated from the fixed contact (2), and a PTC element ( 5), the stationary piece (20), the stationary contact (2), the movable contact (3), the movable piece (30), the thermally responsive element (4) and the PTC element (5), and the case body (10 ) And a lid (11) joined to the main body (10), and an insulative flat case (1) and the fixed piece (20) integrally connected to or connected to the case (1). The terminal portion (21) appearing outside and the movable piece (30) are integrated and continuous. A terminal portion (31) connected and appearing outside the case (1), wherein the PTC element (5) is disposed between the opposing surfaces of the fixed piece (20) and the movable piece (30). The thermal responsive element (4) is formed on the inner bottom surface of the case body (10) in a state of covering the upper surface of the PTC element (5), and the entire outer peripheral edge of the thermal responsive element (4). Alternatively, a part of the surface is positioned by the positioning wall (101) that is in contact with or close to the surface, and a part of one surface is in contact with the PTC element (5) and the other surface is in contact with the movable piece (30) during reversal. Thermal protector characterized by being arranged. A fixed piece (20) having a fixed contact (2) and a movable contact (3) at the tip are brought into contact with the fixed contact (2) by a spring action, and the movable contact (3) is at a predetermined operating temperature. A movable piece (30) comprising a thermally responsive element that reverses away from the fixed contact (2), a PTC element (1) connected to the fixed piece (20), and the fixed piece (20), fixed From the case main body (10) and the lid (11) joined to the main body (10), containing the contact (2), the movable contact (3), the movable piece (30) and the PTC element (5). An insulating flat case (1), a terminal portion (21) which is continuous or connected integrally with the fixed piece (20) and appears outside the case (1), and the movable piece (30). A terminal portion (31) connected and appearing outside the case (1), The PTC element (5) is located between the opposed surfaces of the fixed piece (20) and the movable piece (30), and the movable piece (30) has a reversing portion when operated in the PTC element (5). A thermal protector, wherein the thermal protector is disposed in contact with the heat shield. In the portion of the movable piece (30) in the case (1), a bent portion (33) which is bent so as to be close to the thermally responsive element (4) at the end opposite to the position of the movable contact (3). The thermal protector according to claim 1, wherein The said fixed piece (20) is shape | molded integrally with the bottom part wall of a case main body (10), The metal plate (6) is shape | molded integrally with the said cover body (11), The any one of Claims 1-3 Thermal protector as described in 1. The said metal plate (6) has electroconductivity, is connected to the said movable piece (30), and the said movable piece (30) is shape | molded integrally with the cover body (11). Thermal protector. The thermal protector according to claim 5, wherein a part of the metal plate (6) is exposed to the outside of the case (1) or one surface thereof faces the outside of the case (1). The inner surface of the lid (11) has an inward projection (110) against which the movable piece (30) abuts when the movable contact (3) is separated from the fixed contact (2). The thermal protector in any one of.

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