JP2007317420A - Non-return protecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-return protecting device safely and surely interrupting a circuit by removing opening trouble of a switching element due to spark of plasma discharge at opration of a thermal fuse element. <P>SOLUTION: The non-return protecting device 10 is provided with an electric path separating means connecting in parallel a low-resistance circuit of a thermal fuse element and a high-resistance circuit of a current fusion element. That is, the thermal fuse element consisting of a movable contact body 18, a thermosensitive pellet 20, and a compression spring containing a strong-compression spring 22 and a weak-compression spring 24, and the current fusion element consisting of a high-resistance compression thin-wire spring 26 is housed in a metal case 12 with a pair of lead members 14, 16 fitted. With the protective device in action, the movable contact body is opened and released at a given action temperature, and the compression thin-line spring 26 allows temporary electricity passage to blow out current and interrupt the circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-returnable protective device that prevents contact welding associated with opening of a thermal fuse or the like, and in particular, a thermal fuse element using a temperature sensitive material and a high-resistance current blowing element are combined to safely cut off an electric circuit. The present invention relates to a one-shot type non-return type protective device.

Thermal fuses are used to protect household or industrial electronic and electrical equipment from damage caused by overheating. A thermal fuse is a non-recoverable protective element that has the function of detecting abnormal temperature rise and quickly shutting down the circuit to prevent equipment damage and fire. It is a protective element that safely cuts off the electric circuit. For example, there is known a fusible alloy type thermal fuse using a low melting point fusible alloy which does not contain an environmentally harmful harmful metal as disclosed in Patent Document 1 as a temperature sensitive material. Further, a temperature-sensitive pellet type temperature fuse using a temperature-sensitive material molded body as a temperature-sensitive material is known for a high current of 6A or more, although the nominal rated current is as wide as 0.5A to 15A. Of these, Patent Document 2 discloses a temperature-sensitive pellet type thermal fuse that operates at a predetermined operating temperature using a temperature-sensitive pellet made of a thermoplastic resin. Further, Patent Document 3 stores a pellet formed by molding an insulating chemical substance together with a movable electrode and a strong and weak spring in a metal case, which is a typical structure of a temperature sensitive pellet type thermal fuse, and hermetically seals to provide a lead out lead. Among the thermal fuses, those in which the pellets used are composed of a combination composition of different organic compounds are mentioned. On the other hand, in Patent Documents 4 and 5, as a high-load temperature fuse, using a fusible solder tablet filled in a casing and a slidable operating pin, the contact spring is operated by sliding the operating pin and cut. A temperature safety switch to turn off is disclosed. However, in these thermal fuses, there is a possibility that spark or arc discharge occurs at the time of dissociation or breaking of the contact, and the contact portion is melted to cause contact welding.
JP 2005-276577 A JP 2003-317589 A JP 2002-163966 A JP-A-4-212234 JP-A-56-67130

  Conventionally, when the circuit of the above-described thermal fuse is interrupted at a predetermined operating temperature, the contact portion is welded to cause a failure in the circuit interrupt. For example, in a temperature sensitive switch for high voltage, high current and high load, or a temperature sensitive pellet type thermal fuse where the temperature sensitive material is gradually deformed and the contact is gradually opened, chattering occurs at the time of interruption. There is a problem that the contact portion melts and is damaged. Such a problem occurs when a high load or a large current is used. For example, a spark may be generated when the contact is opened at the operating temperature, or welding of the contact portion may be caused by an operating current, which may make it difficult to perform a reliable and safe breaking operation. In particular, in the case of a thermal fuse used in a DC circuit, it is conceivable that troubles such as plasma discharge being continued due to circuit interruption and safe interruption cannot occur. In addition, even in a fusible alloy type thermal fuse without a movable contact, an unstable resistance such as a decrease in insulation resistance or a case breakage due to sparks or arc discharge between electrodes generated when the melted molten alloy is cut off at the time of fusing. May cause dissociation or malfunction. Therefore, some measures are required to avoid troubles that occur when the circuit path of the thermal fuse is opened, and the provision of a one-shot type protection device including a non-recoverable temperature safety switch or a thermal fuse that can always safely shut off the circuit. Was desired.

  Therefore, the present invention has been proposed to eliminate the above-mentioned drawbacks, and in a one-shot type thermal fuse that is a one-time operation, the electric circuit is dissociated or physically caused by a chemical change at a predetermined operating temperature. It is an object of the present invention to provide a new and improved protection device that can prevent the occurrence of problems such as welding due to sparks or plasma discharge when it is opened by separation due to various changes and can safely shut off an electric circuit.

  In particular, when the switching member is operated using the physical deformation of the temperature sensitive material and the deformation characteristics of the temperature sensitive material are not steep, specifically, the softening of a thermoplastic resin or the like is used or the heating is slow. To provide a current fuse function and safely shut off the circuit as an effective means for unstable operation, such as when it is gradually deformed or used in a high voltage / current load circuit or DC circuit An object of the present invention is to provide a non-returnable protective device improved.

  According to the present invention, a switching member including a temperature sensitive material having a predetermined operating temperature is accommodated in a case in which a pair of lead members forming a main electric circuit is attached, and a low resistance circuit and a high resistance circuit are interposed between the lead members. An electric circuit disconnecting means comprising a parallel circuit is connected and arranged, and the low-resistance circuit is opened at a predetermined operating temperature of the temperature-sensitive material, and immediately after that, the high-resistance circuit is allowed to be temporarily energized and opened. There is provided a non-returnable protective device for electrically interrupting a main electric path between lead members. Here, the electric circuit disconnecting means is a temperature fuse element in which the low resistance circuit uses a temperature sensitive material, the high resistance circuit is a current fusing element, and the current fuse element is opened after the operation of the temperature fuse element. Cut off. In other words, the low resistance circuit is a fusible alloy type temperature fuse using a low melting point fusible alloy or a temperature sensitive pellet type temperature fuse using a temperature sensitive pellet, and the high resistance circuit is a low resistance circuit. After the operation of, the circuit is interrupted by temporarily allowing energization and dissociating or breaking by current blowing. Hereinafter, dissociation or separation is unified and used as separation. For example, when the high resistance circuit is a current fusing element, it consists of a high resistance thin metal wire electrically connected in parallel with the thermal fuse element and acts as a high resistance bypass circuit connected between a pair of electric circuit lead members. This is a protective device that allows the energization to be temporarily released after the thermal fuse element is operated at a predetermined operating temperature, thereby breaking the circuit.

  As the temperature sensitive material of the temperature fuse element, a low melting point soluble alloy is used in the case of a fusible alloy type temperature fuse, and a temperature sensitive material molded body is used in the case of a temperature sensitive pellet type temperature fuse. In the latter temperature-sensitive pellet type thermal fuse, there is provided a switching member in which the low-resistance circuit of the electric circuit disconnecting means is arranged on one electrode side of the electric circuit lead member and responds to physical deformation of the thermosensitive material molded body. The current fusing element as a high resistance circuit is in an electric circuit formed by a pair of electric circuit lead members, and a coiling compression spring of a high resistance metal thin wire electrically connected in parallel with the switching member, or It can be comprised of a low melting point soluble metal piece. In addition, when using a low-melting-point soluble metal piece, it has a melting point lower than the predetermined operating temperature of the temperature-sensitive material molded body on which the switching member operates and operates in a molten state before the temperature-sensitive material molded body operates. Immediately after that, the non-return type protective device that allows temporary energization and interrupts the circuit.

  More specifically, the temperature-sensitive pellet type thermal fuse element is configured such that a switching member including a movable contact body and a compression spring is accommodated in a cylindrical metal case, and a pair of electric circuit lead members is provided at one end of the cylindrical metal case. The first lead in which the cylindrical metal case is hermetically sealed through the insulating material and the second lead directly caulked and fixed on the other end side of the cylindrical metal case, and the movable contact body on the electrode side of the first lead Is configured to be separable, and at normal temperature, the pressing force of the compression spring against the movable contact body is applied to maintain the conductive state in which the movable contact body is in pressure contact with the first lead. Disclosed is a non-returnable protective device that switches to a closed state that opens and closes with a first lead in response to physical deformation of the body. Here, the compression spring uses a weak compression spring and a strong compression spring to apply a pressing force to the star-shaped movable contact body. On the other hand, the current fusing element as a high resistance circuit is disposed between the first lead and the movable contact body using a compression thin wire spring coiled with a high resistance thin wire. A low melting point metal piece can also be used for the current fusing element. In this case, the low melting point metal piece is contacted with the movable contact body by using a weak compression spring and a strong compression spring that apply a pressing force to the movable contact body. A structure to be arranged is disclosed.

Further, the thermal fuse element includes a case that accommodates a temperature-sensitive material molded body and an operation rod disposed in contact with the molded body, and is configured by a pair of lead leads attached to the case with a lead member for an electric circuit, A switching member is attached to one end of the lead and a movable contact spring that applies a pressing force by the displacement of the operating rod. A current fusing element is connected and arranged between the pair of lead, and the movable contact spring is The other end of the lead is brought into pressure contact with the other end of the lead by the action of the pressing force of the operating rod, and the conducting state is maintained. At the predetermined operating temperature, the operating rod is displaced by physical deformation of the thermosensitive material molded body, and the other end is displaced. Disclosed is a non-return type protective device that is separated from the part and switches to a cut-off state.

  The non-recoverable protection device of the present invention is a protection device in which a current fusing element is connected in parallel to an electric circuit disconnecting means that is electrically connected to a pair of lead members of a thermal fuse element. This prevents the occurrence of problems due to sparks and plasma discharges, and allows safe and reliable shut-off operation. In other words, the circuit breaking operation is safely and reliably achieved through the two steps of the opening and closing operation by the temperature sensitive material and the subsequent opening and closing operation by energizing the current fusing element. For example, a fusible alloy or switching member is interposed between a pair of electrodes as a temperature fuse element, and a high resistance bypass circuit is formed by providing a high resistance thin wire spring between both electrodes of a lead member as a current fusing element The first stage opening / closing is performed by a switching member, and the second stage opening / closing is blown by energization heat generation of a high resistance thin wire spring, and the non-conduction state is made stepwise through two steps. In this case, the current is suppressed by energizing the high resistance, and then the thin wire spring is heated and melted and melted, so that the load when the circuit is finally shut down is also suppressed. Therefore, it is possible to provide an improved non-returnable protective device that can safely and reliably cut off an electric circuit without any problems associated with sparks or plasma discharge.

  The non-returnable protection device of the present invention includes an electric circuit disconnecting means in which a temperature sensitive material having a predetermined operating temperature is accommodated in a case to which a pair of electric circuit lead members are attached, and a low resistance circuit and a high resistance circuit are connected in parallel. The low-resistance circuit is opened at the operating temperature of the temperature sensitive material, and then the high-resistance circuit is opened by current blowing or the like to electrically cut off the electric-circuit lead members. For example, the low resistance circuit of the electric circuit disconnecting means is configured as a temperature fuse element using a temperature sensitive material, and the high resistance circuit is configured as a current fusing element. In a first embodiment of the present invention, the temperature sensitive material is a temperature sensitive pellet type temperature fuse element using a temperature sensitive material molded body, and the switching member that responds to physical deformation of the temperature sensitive material molded body is used for an electric circuit. The high-resistance circuit is a high-resistance metal thin wire that is arranged on one electrode side of the lead member and is electrically connected in parallel with the switching member, and temporarily energizes and shuts off the circuit after the thermal fuse element is activated. Is a non-returnable protection device. Here, the switching member of the temperature-sensitive pellet type thermal fuse element has a movable contact body and a compression spring accommodated in a cylindrical metal case, and a pair of electric circuit lead members hermetically seals one end of the cylindrical metal case. The first lead that penetrates the insulating material and the second lead that is directly caulked and fixed at the other end of the cylindrical metal case, and the movable contact body is arranged to be separable on the electrode side of the first lead. The pressing force of the compression spring is applied to keep the movable contact body in a conductive state in pressure contact with the first lead, and at a predetermined operating temperature, it acts on the physical deformation of the thermosensitive material molded body and opens and separates from the first lead. Switch to the shut-off state to release. The high-resistance metal thin wire is a current fusing element made of a coiled compression thin wire spring. The compression spring includes a weak compression spring and a strong compression spring, and presses the movable contact body. When the protective device is operated at a predetermined operating temperature, even when the energizing current does not cause the compression thin wire spring to melt, the weak compression spring further pushes the movable contact member to disconnect the contact with the thin wire spring. As a result, the circuit is reliably shut off. As a result, after the first lead of the low-resistance circuit and the movable contact body are separated and opened, current is blown as a second step without causing sparks or plasma discharge by energizing the high-resistance circuit, and is safe. Switching in a reliable cut-off state is performed. That is, the first step when the thermosensitive pellet is physically deformed at a predetermined operating temperature by cooperation of the weak compression spring and the strong compression spring of the compression spring that applies a pressing force to the movable contact body, and the next compression wire A one-shot type non-return type protective device that switches to a cut-off state in the second step of fusing by an energization current to the spring is provided.

  The second embodiment of the present invention is a structural modification when the above-described temperature-sensitive pellet type thermal fuse element is used. That is, the temperature-sensitive material is a temperature-sensitive pellet type temperature fuse element using a temperature-sensitive material molded body, and a switching member that responds to physical deformation of the temperature-sensitive material molded body is provided on one electrode side of the electric circuit lead member. The low-melting-point fusible metal body is disposed in parallel with the switching member, and the melting point of the fusible-melting metal body is selected to be lower than the operating temperature of the temperature-sensitive material. Thus, the non-return type protective device is characterized in that the molten state is exhibited before the operation of the thermal fuse element, and the circuit is interrupted by allowing temporary energization after the operation. Also in this case, the switching member of the temperature-sensitive pellet type thermal fuse element has a movable contact body and a compression spring accommodated in a cylindrical metal case, and a pair of electric circuit lead members hermetically seals one end of the cylindrical metal case. A first lead that penetrates the insulating material and a second lead that is caulked and fixed at the other end of the cylindrical metal case. The movable contact body is detachably disposed on the electrode side of the first lead, and is a compression spring at room temperature. The movable contact body is maintained in a conductive state in pressure contact with the first lead by applying a pressing force, and at a predetermined operating temperature, it acts on the physical deformation of the thermosensitive material molded body to separate and open the first lead. The low melting point metal element is a current fusing element made of a low melting point metal piece, and the compression spring includes a weak compression spring and a strong compression spring, and presses against the movable contact body. The low-melting metal piece is brought into contact with the movable contact causes the use. In this case, the low melting point metal piece is softened and melted immediately before reaching the predetermined operating temperature, and even if the movable contact body is separated and opened, energization by the soft melting and melting state piece is allowed for a while, and the spark is melted. And complete shutdown while preventing discharge.

  The third embodiment of the present invention is a case where the above-described temperature-sensitive pellet type thermal fuse element is used, but the configuration of the switching member is different, and is a protective device suitable for a high-load electric circuit. . Specifically, the low-resistance circuit is a thermal fuse element having a case body that accommodates a temperature-sensitive material molded body and an operating rod disposed in contact with the molded body, and is used for physical deformation of the temperature-sensitive material molded body. The responsive switching member is arranged on one electrode side of the electric circuit lead member, and the electric circuit lead member is composed of a pair of lead leads attached to the case body, and the switching member is mounted on one end portion of the lead lead and operates. It consists of a movable contact spring that presses the rod, and the high resistance circuit is a current fusing element consisting of a high resistance metal thin wire that is connected between a pair of lead leads and electrically connected in parallel with the movable contact spring. At normal temperature, the other end of the lead is brought into pressure contact with the other end of the lead by the action of the pressing force of the operating rod, and is kept in a conductive state. Moving rod is moved away to open the other end, after the operation is switched to the blocked state current fusing element to permit temporarily energized. In other words, it is provided with a case that accommodates the actuating rod and the temperature-sensitive material molded body, and is composed of a movable contact spring attached to one electrode end portion of the lead lead attached to the case, and a current fusing element between the pair of lead leads. A high resistance circuit is connected and arranged. Here, the movable contact spring is brought into pressure contact with the lead-out lead at the normal temperature by the action of the pressing force of the operating rod to maintain the conduction state, and at a predetermined operating temperature, the operating rod is shifted by physical deformation of the thermosensitive material molded body. Then, the movable contact spring is separated and opened to cut off the thermal fuse element, and then the high-resistance current blowing element is blown off by energization heat generation to switch the circuit to a complete cut-off state. In this way, the non-return type protective device that performs stable and reliable circuit interruption by preventing discharge at the time of cut-off or contact welding during operation even in a high load circuit is provided.

  According to a fourth embodiment of the present invention, there is provided a fusible alloy type thermal fuse element in which a low melting point fusible alloy with a flux coating as a low resistance circuit is connected between electrode portions of a pair of electric circuit lead members attached to a case. A one-shot type non-return type protective device including a current fusing element made of a thin metal wire having high resistance as a high resistance circuit is disclosed. Also in this case, as in the above-described embodiment, first, the thermal fuse element is activated and opened, and then the current blowing element is activated and opened after temporary energization, so that spark and discharge are suppressed, and spark and discharge are prevented. Switching to a safe and reliable shut-off state is achieved by preventing the occurrence of the trouble involved.

  Example 1 which is the first embodiment of the present invention is a non-return type protective device that eliminates a trouble of opening of a switching member due to occurrence of sparks or plasma discharge during operation of a thermal fuse element, and safely and reliably interrupts the circuit. I will provide a. Hereinafter, the non-returnable protective device shown in FIG. 1 will be described in detail with reference to the drawings. The non-returnable protective device 10 of the present invention includes an electric circuit disconnecting means in which a low resistance circuit of a thermal fuse element and a high resistance circuit of a current fusing element are connected in parallel in a metal case 12 having good conductivity and thermal conductivity. Specifically, the movable contact body 18, the temperature sensitive pellet 20, a thermal fuse element composed of a compression spring including a strong compression spring 22 and a weak compression spring 24, and a high resistance compression arranged in parallel connection with the movable contact body 18. A current fusing element comprising a thin wire spring 26 is accommodated in the metal case 12 to which the pair of lead members 14 and 16 are attached. In operation, this protective device opens and closes the movable contact body at a predetermined operating temperature, and the compression thin wire spring 26 temporarily allows energization and blows off the current to break the circuit. FIG. 1A shows the protection device 10 of the present invention in a state at room temperature. That is, a switching member and a high-resistance metal thin wire material are housed in the cylindrical metal case 12 to which the pair of lead members 14 and 16 are attached as electric circuit disconnecting means. The switching member includes a movable contact body 18, a temperature sensitive pellet 20, and a compression spring including a strong compression spring 22 and a weak compression spring 24. On the other hand, the high-resistance metal fine wire is composed of a compression fine wire spring 26 connected in parallel with the movable contact body 18. As the switching member, two pressing plates 28 and 30 are arranged before and after the strong compression spring 22 to stabilize the operation. On the other hand, the metal case 12 is molded into a cylindrical body, and the opening at one end thereof is closed with an insulating soot tube 32 penetrating the first lead member 14 and hermetically sealed with an insulating material 33 of a sealing resin. The opening of the other end of the metal case 12 is closed by caulking and fixing the second lead member 16 at the end. Here, the compression wire spring 26 obtained by coiling a high-resistance metal wire is disposed between the first lead member 14 and the movable contact body 18 so as to be electrically connected in parallel. As shown in FIG. 1B, the compression thin wire spring 26, which is a current fusing element, has a movable contact body 18 in which the anchoring portion 19 on the distal end side of the first lead member 14 and the distal electrode portion 17 are in contact with each other. Between the two, they are disposed in a pressure contact state and are electrically connected. The compression thin wire spring 26 is used as a high resistance circuit, and is always in contact with the first lead member 14 and the movable contact body 18, and temporarily has a high resistance when the movable contact body 18 and the lead end electrode portion 17 are separated. The bypass circuit is formed. At a predetermined operating temperature at which this protective device operates, the temperature sensitive pellet 20 is temporarily opened by the movable contact body 18 forming a low resistance circuit being separated from the tip electrode portion 17 as shown in FIG. In addition, the current is regulated by the thin wire compression spring 26 to prevent the occurrence of sparks, and immediately after the heat is melted, the compression wire spring 26 is broken and opened to achieve stable circuit interruption. Here, the resistance value of the high resistance circuit is several tens of ohms, which is several times the resistance value of the low resistance circuit in the protection device of 100 V and 10 A, but even if there is no disconnection due to current, the temperature sensitive pellet The contact between the compression thin wire spring 26 and the movable contact body 18 is separated by the melting of 20 and the large stroke action on the weak compression spring 24 side.

  A second embodiment shown in FIG. 2A shows a non-returnable protection device 30 according to a modification of the first embodiment described above, and the same portions are denoted by the same reference numerals. Specifically, as shown in an enlarged view in FIG. 2B, a low melting point metal piece 27 is used instead of the compression thin wire spring of the first embodiment. The low melting point metal piece 27 is formed by processing a metal alloy material having a melting point lower than a predetermined operating temperature of the temperature sensitive pellet into a ring shape that can be easily assembled. The lead member 14 is assembled between the tip electrode portion 17 and the lead member 14. In operation, the low melting point metal piece 27 is present in a molten state at the time of opening and breaking at a predetermined operating temperature, and a spark generated immediately after the opening of the opening is prevented by temporarily energizing the molten metal piece. That is, the molten alloy of the low-melting-point metal piece 27 is interposed between the tip electrode portion 17 of the lead member 14 and the movable contact body 18 to prevent welding and lead to stable circuit interruption.

  As shown in FIG. 3, the non-returnable protection device 40 according to the third embodiment of the present invention has a thermosensitive material molded body 50 accommodated in a case with respect to a pair of lead members 44 and 46 attached to the insulating case 42. The working rod 52 in contact with the lead member 44 always supports the movable contact member 48 coupled to the one lead member 44 and is connected to the tip electrode portion 47 of the other lead member 46 in a pressure contact state. On the other hand, a high resistance thin wire 56 of a high resistance circuit is connected between the aforementioned tip electrode portion 47 and the movable contact body 48. Accordingly, when the thermosensitive material molded body 50 is melted at a predetermined operating temperature, first, the action rod 52 moves and the movable contact body 48 is released from the tip electrode portion 47, and then the current fusing element of the high resistance thin wire 56 is opened. By fusing, reliable circuit interruption between the pair of lead members 44 and 46 is performed. Here, the movable contact body 48 is provided at the distal end portion of the first lead member 44 made of an elastic metal member, and a downward force that opens and closes by an elastic force always acts on the temperature-sensitive material 50. A low resistance circuit is configured by maintaining the contact state with the tip electrode portion 47 of the second lead member 46 by the action rod 52 supported by the above. Therefore, an electric circuit disconnecting means is constituted by the low resistance circuit and the high resistance thin wire 56, and the non-return type protective device achieves the breaking operation safely and reliably.

  FIG. 4 shows an embodiment of a non-return type protective device 60 using an alloy type thermal fuse element which is another type. In the figure, a low melting point soluble alloy 68 and a high resistance thin wire 76 attached between the tip electrodes of a pair of lead members 64 and 66 are accommodated in an insulating package sealed with an insulating material 63 on a cylindrical insulating case 62. A protection device 60 is configured. Here, the low melting point soluble alloy 68 has a flux 70 deposited on its surface and functions as a low resistance circuit between a pair of lead members 64 and 66 extending through the insulating material 63 of epoxy resin. Similarly, the high resistance thin wire 76 connected between the pair of lead members constitutes a high resistance circuit connected in parallel with the low resistance circuit, and both constitute an electric circuit disconnecting means. In operation, the low melting point soluble alloy 68 is melted at a predetermined operating temperature, and the low resistance circuit formed between the pair of lead members 64 and 66 is separated and opened, but the high resistance thin wire of the high resistance circuit is temporarily opened. Since 76 allows energization, no spark or arc discharge occurs. Thereafter, the current fusing element of the high resistance thin wire 76 is blown, and the circuit is completely cut off. Therefore, the safe and reliable operation of the non-return type protective device using the alloy type thermal fuse element can be realized.

1 is a non-returnable protective device using the temperature sensitive pellet type thermal fuse element shown in Example 1 of the present invention, FIG. 1 (a) is a longitudinal sectional view at normal temperature, and FIG. 1 (b) is an enlarged longitudinal sectional view of a main part. FIG. 1 and FIG. 1C are longitudinal sectional views during operation. Similarly, FIG. 2 is a modification of FIG. 1 shown in Example 2, in which FIG. 2 (a) is a longitudinal sectional view at normal temperature, and FIG. 2 (b) is an enlarged longitudinal sectional view of an essential part thereof. FIG. 6 is a cross-sectional view of a non-returnable protection device using another temperature-sensitive pellet type thermal fuse element shown in the third embodiment. FIG. 9 is a cross-sectional view of a non-returnable protection device using another fusible alloy type thermal fuse element shown in the fourth embodiment.

Explanation of symbols

10, 30, 40, 60; non-returnable protective device, 12; metal case,
14, 44, 64; first lead member; 16, 46, 66; second lead member;
17, 47; tip electrode part, 18, 48; movable contact body (low resistance circuit), 19; mooring part,
20, 50; temperature-sensitive pellets or temperature-sensitive material molded body, 22; strong compression spring (compression spring),
24; weak compression spring (compression spring), 26; compression wire spring (high resistance circuit),
27; low melting point metal piece (high resistance circuit), 28, 30; pressing plate, 32;
33, 63; insulating material, 42, 62; insulating case, 52; working rod,
56, 76; high resistance thin wire (high resistance circuit), 68; fusible alloy (low resistance circuit),
70; flux.

Claims (10)

  A temperature sensitive material having a predetermined operating temperature is accommodated in a case to which a pair of electric circuit lead members are attached, and electric circuit disconnecting means in which a low resistance circuit and a high resistance circuit are connected in parallel is connected between the electric circuit lead members. And the low resistance circuit is opened at the operating temperature of the temperature sensitive material, and then the high resistance circuit is opened to electrically cut off between the electric circuit lead members.   2. The non-return type protective device according to claim 1, wherein the electric circuit disconnecting means is a thermal fuse element in which a low resistance circuit uses the temperature sensitive material and a high resistance circuit is a current fusing element.   The temperature sensitive material is a fusible alloy type thermal fuse element using a low melting point fusible alloy, and the high resistance circuit is a thin metal wire electrically connected in parallel with the low melting point fusible alloy, 2. The non-returnable protective device according to claim 1, wherein the circuit is interrupted by temporarily allowing energization after the operation of the element.   The temperature-sensitive material is a temperature-sensitive pellet type temperature fuse element using a temperature-sensitive material molded body, and a switching member that responds to a physical deformation of the temperature-sensitive material molded body is on one electrode side of the electric circuit lead member The high resistance circuit is a thin metal wire electrically connected in parallel with the switching member, and temporarily energizes after the operation of the thermal fuse element to cut off the circuit. The non-returnable protective device according to 1.   The switching member of the thermal fuse element has a movable contact body and a compression spring accommodated in a cylindrical metal case, and the lead member for the electric circuit passes through an insulating material hermetically sealed at one end of the cylindrical metal case. And a second lead that is caulked and fixed on the other end side of the cylindrical metal case, and the movable contact body is arranged to be separable on the electrode side of the first lead, and the pressing action of the compression spring at room temperature The movable contact body is brought into pressure contact with the first lead to maintain a conductive state, and the first lead and the movable contact body are separated and opened at an operating temperature at which the thermosensitive material molded body is physically deformed. The non-return type protective device according to claim 4, wherein the non-return type protective device is switched to a state.   6. The non-return type according to claim 5, wherein the thin metal wire is a coiled compression thin wire spring, and the compression spring includes a weak compression spring and a strong compression spring, and applies a pressing force to the movable contact body. Protective device.   The temperature-sensitive material is a temperature-sensitive pellet type temperature fuse element using a temperature-sensitive material molded body, and a switching member that responds to a physical deformation of the temperature-sensitive material molded body is on one electrode side of the electric circuit lead member The high resistance circuit is a low melting point soluble metal body having a melting point lower than the operating temperature arranged in electrical parallel with the switching member, and exhibits a molten state before the operation of the thermal fuse element. The non-return type protective device according to claim 1, wherein the circuit is interrupted by allowing temporary energization after operation.   The switching member of the temperature-sensitive pellet type thermal fuse element includes a movable contact body and a compression spring housed in a cylindrical metal case, and the lead member for the electric circuit is an insulating material hermetically sealed at one end of the cylindrical metal case A first lead that penetrates the second lead and a second lead that is caulked and fixed at the other end of the cylindrical metal case, and the movable contact body is arranged to be separable on the electrode side of the first lead. The pressing force of the compression spring is applied to maintain the movable contact body in a conductive state in pressure contact with the first lead, and acts on physical deformation of the thermosensitive material molded body at a predetermined operating temperature. The non-return type protective device according to claim 7, wherein the non-return type protective device is switched to a cut-off state where one lead is separated and opened.   The low-melting-point fusible metal body is a current fusing element made of a low-melting-point metal piece, and the compression spring includes a weak compression spring and a strong compression spring, and applies a pressing force to the movable contact body and also the low-melting-point metal piece. The non-return type protective device according to claim 8, wherein the movable contact body is brought into contact with the movable contact body. The low-resistance circuit is a thermal fuse element having a case body that accommodates a temperature-sensitive material molded body and an operating rod, and is moved by an operating rod that responds to physical deformation at an operating temperature of the temperature-sensitive material molded body. The switching member is disposed on one electrode side of the electric circuit lead member, and the electric circuit lead member is a pair of lead leads attached to the case body, and the switching member is attached to one end thereof, The high-resistance circuit is connected and arranged between the lead-out leads, and is configured by a current fusing element made of a high-resistance metal body electrically connected in parallel with the switching member. The other end of the lead-out lead is brought into pressure contact and maintained in a conductive state, and at a predetermined operating temperature, the temperature-sensitive material molded body is deformed by physical deformation. 2. The non-returning type according to claim 1, wherein a displacement of the operating rod opens and separates from the other end, and after this operation, the current fusing element temporarily allows energization and switches to a cut-off state. Protective device.

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