Abstract:
A circuit breaker device including a first connection terminal, a second connection terminal, a heating portion electrically interconnecting the first connection terminal and the second connection terminal, and a claw lockingly engaged with the heating portion. The claw is configured to be melted by the heating portion to allow the heating portion to move apart from the first connection terminal and the second connection terminal for electrical disconnection.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a circuit breaker device that breaks an electric circuit in a short time. 
     2. Description of the Related Art 
     In an electric equipment system provided on a vehicle, a large current fuse that has been disposed between the battery and the wire harness is cut off by fusion when some abnormality or other has occurred, for example, in a load, such as a power window, or in a wire harness constructed of a plurality of electric wires connecting a battery and each load, etc. By doing so, a break is made between the battery and the wire harness to thereby prevent the respective loads or wire harness from being damaged by burning. 
     However, in such an electric equipment system using a large current fuse, even when some abnormality or other has occurred in a load, such as a power window, or in a wire harness constructed of a plurality of electric wires connecting a battery and each load, etc., the large current fuse is not cut off by fusion unless an electric current of a magnitude greater than a permissible value that is preset in the large current fuse occurs. In this view, there have been developed protection apparatuses of bi-metal type and fusible conductor type that sense this flowage and makes a break between the battery and the wire harness when a large current of a magnitude near the permissible value is continuously flowing therethrough. 
     SUMMARY OF THE INVENTION. 
     However, in the protection apparatus of bi-metal type, using a bi-metal, wherein two kinds of metal whose coefficients of thermal expansion differ from each other, it is detected whether a large current is flowing through a fusible member. Therefore, when the magnitude of the current flowing through the fusible member is changed, the bi-metal is deformed with the result that the length of time that is needed until the breakage of the circuit changes. 
     For this reason, when a trouble has occurred, such as that wherein a large magnitude of current intermittently flows, it happens that the temperature of the fusible member ceases to rise beyond a certain value of temperature. As a result, there was the possibility that the wire harness or the load excessively generated heat before the protection apparatus broke the circuit. 
     On the other hand, in the protection apparatus of fusible conductor type, using a coil made of a shape memory alloy, it is detected whether a large magnitude of current is flowing through the fusible conductor line. Therefore, when the magnitude of the current flowing through the fusible conductor line is changed, the coil is deformed, with the result that the length of time that is needed until the breakage of the circuit changes. 
     For this reason, when a large magnitude of current intermittently flows, it happens that the temperature of the fusible conductor line ceases to rise beyond a certain value of temperature. As a result, there was the possibility that the wire harness or the load excessively generated heat before the protection apparatus broke the circuit. Also, in a case where using bi-metal or shape memory alloy, the temperature at which the deformation starts is ordinarily as low as approximately 100° C. Therefore, bi-metal or shape memory alloy was difficult to use at a temperatures of 120° C. to 125° C., which is the environmental-of-use conditions of a vehicle. 
     Also, in both protection apparatuses, the response-to-heat length of time of the bi-metal or coil, which is a heat-deformable electricity conductor member, was influenced by the passage of current through it. Furthermore, there were cases where at the time of an abnormality (the passage of current in excess) the response to heat of the heat-deformable electricity conductor member did not occur timely. 
     An object of the present invention is to provide a circuit breaker device that when an abnormality signal on the vehicle can break the circuit shortly and reliably, and protect a relevant electric circuit. 
     To achieve the above object, the present invention provides a circuit breaker device. The device has a first connection terminal; a heating portion which is filled with a heating agent and has a conductivity; and a first contact member for conductively joining the heating portion to the first connection terminal. The first contact member has contact portions and opening portions. 
     Preferably, each of the opening portions is a slit portion which consists of a slender groove. 
     Preferably, each of the contact portions and the slit portions are alternately formed. 
     Preferably, the first contact member is mounted to the first connection terminal, and the contact portions are brought in contact with the heating portion. 
     Preferably, the-first contact member is mounted to the eating portion, and the contact portions are brought in contact with the first connection terminal. 
     Preferably, the device further has a second connection terminal; and a second contact member for conductively joining the heating portion to the second connection terminal. The second contact member has contact portions and opening portions. 
     Preferably, the device further has a claw portion which is lockingly engaged with the heating portion. 
     Preferably, the claw portion is made of resin. 
     Preferably, the device further has an outer vessel which is fixed with the claw portion. The outer vessel accommodates the heating portion. 
     Preferably, the device further has an elastic member which is arranged to contact with the heating portion. The elastic member is for biasing the heating portion to the claw portion. 
     Preferably, the device further has an ignition portion for igniting the heating agent by an abnormal signal from outside at abnormality of a vehicle. 
     Preferably, the outer vessel has an upper casing and a lower casing. The upper casing is formed with a first threaded portion. The lower portion is formed with a second threaded portion which is screwed to the first threaded portion. 
     Preferably, the device further has an outer vessel which accommodates the heating portion. The first connection terminal is integrally formed to the outer vessel. 
     Preferably, the device further has an out vessel which accommodates the heating portion. The second connection terminal is integrally formed to the outer vessel. 
     Preferably, the heating agent is a thermit agent which has a metal oxide powder and an aluminum powder mixed with the metal oxide powder. 
     According to the present invention, for example, a first connection terminal or a second connection terminal is connected to a heating portion via a first or second contact member, whereby a power is supplied from a battery to a load. Also, when an ignition portion gets ignited due to an abnormality signal from outside, a heating agent filled in the heating portion generates heat, whereby due to this heat, claw portions, each formed on an outer vessel and made of resin material, are melted. For this reason, an elastic member is expanded with the result that the heating portion is pushed upward while sliding on the first or second contact member. Therefore, the electric connection between the heating portion and one of the first and the second connection terminals is cut off. Therefore, it is possible to cut off the circuit shortly and reliably and to thereby protect relevant electric parts. 
     Also, since the first or second contact member is a multi-contact spring, and wherein slit portions consisting of a slender groove and contact portions electrically contacted with the heating portion are formed alternately two or more in number, the resistance to sliding is small. Therefore, it is possible to easily cut off the circuit and, in addition, since the resistance to contact is small, it is possible to lessen the generation of heat when a large current passes through. 
     Also, when an upper casing is fitted onto a lower casing, a first threaded portion formed on the upper casing is screwed onto a second threaded portion formed on the lower casing. As a result, when breakage of the circuit is done, the heating portion ceases to pop out, nor is there a fear that a relevant person will be scorched due to the heat. 
     Also, since the first or the second connection terminal is formed integrally with the outer vessel, only a small number of parts items to be assembled are needed, with the result that the number of operation steps can be reduced. 
     Also, the heating agent can generate a heat of thermit reaction due to the thermit reaction. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     FIG. 1 is a sectional view taken along a line A 1 —A 1  of a circuit breaker according to a first embodiment of the present invention before the circuit is broken; 
     FIG. 2 is an upper surface view illustrating the circuit breaker according to the embodiment; 
     FIG. 3 is a sectional view taken along a line B 1 —B 1  of the circuit breaker according to the embodiment; 
     FIG. 4 is a constructional view illustrating a multi-contact spring; 
     FIG. 5 is a structural view illustrating a multi-contact socket; 
     FIG. 6 is a structural view illustrating a slot contact socket; 
     FIG. 7 is a characteristic diagram illustrating the insert/draw-off forces of a multi-contact socket and a slot contact socket; 
     FIG. 8 is a diagram illustrating the resistance to contact of the multi-contact socket and that of the slot contact socket; 
     FIG. 9 is a sectional view taken along a line A 1 —A 1  of the circuit breaker according to the embodiment after the circuit has been broken; and 
     FIG. 10 is a sectional view illustrating a circuit breaker according to a second embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of a circuit breaker according to the present invention will now be explained in detail with reference to the drawings. 
     First Embodiment 
     The circuit breaker according to the embodiment is characterized in that, using multi-contact springs, upon an input to it of an abnormality signal on a vehicle the circuit can be reliably broken in a short time to thereby protect relevant electric parts. 
     In the circuit breaker illustrated in FIG. 1, a plate-like long first bus bar  11 , a first connection terminal, consists of, for example, copper or a copper alloy. This first bus bar  11  has formed therein a round hole portion  12  connected to a battery, etc. The first bus bar  11  has formed thereon a bent portion  8  that has been bent at a substantially right angle. And this bent portion  8  and a forward end portion  13  of the bus bar are inserted into a resin casing  17 , or a lower casing, by integral forming (insert molding). 
     Also, a plate-like long second bus bar  14 , a second connection terminal, consists of, for example, copper or a copper alloy. This second bus bar  14  has formed therein a round hole portion  15  connected to a load, etc. The second bus bar  14  has formed thereon a bent portion  10  that has been bent at a substantially right angle. And this bent portion  10  and a forward end portion  16  of the bus bar are inserted into the resin casing  17  by integral forming (insert molding). 
     Between the first bus bar  11  and the second bus bar  14  are disposed the resin casing  17  and a cap  19 , or an upper casing. The cap  19  is made to cover the resin casing  17 . The cap  19  and the resin casing  17  constitutes an outer vessel, which consists of a vessel made of insulating material such as resin (thermoplastic resin). 
     Within the resin casing  17  is accommodated a heating agent casing  22  that consists of copper and a copper alloy. This heating agent casing  22  is filled with a heating agent  23 , and in this heating agent casing  22  there is accommodated an ignition portion  24 . 
     The ignition portion  24  has an ignition agent. It is arranged to cause the ignition of the ignition agent by the heat generated due to the electric current that, at the time of an abnormality of the vehicle, such as, a collision accident or the like of the vehicle, flows into a lead wire  31 . This ignition causes the generation of a heat of thermit reaction in the heating agent  23 . 
     On the bus bar forward end  13  is mounted a multi-contact spring  21   a , a first contact member, with a conductivity. Also, on the bus bar forward end portion  16  there is mounted a multi-contact spring  21   b , a second contact member, with a conductivity. The multi-contact spring  21   a  and the multi-contact spring  21   b  are disposed opposing each other and in such a way as to clamp a side wall portion of the heating agent casing  22 , as illustrated in FIGS. 1 and 2. For this reason, the first bust bar  11  and the second bus bar  14  can be electrically connected to each other via the multi-contact springs  21   a ,  21   b  and the heating agent casing  22 . Each of the multi contact springs may be multiple leafed springs as shown in FIG.  4 . 
     As illustrated in FIG. 4, each of the multi-contact springs  21   a ,  21   b , when viewed from an upper surface side and a side surface side, is shaped like a circular arc. Each of the multi-contact springs  21   a ,  21   b  has a construction wherein a slit portion  27   a ,  27   b , consisting of a slender groove, and a contact portion  28   a ,  28   b , electrically contacted with the heating agent casing  22 , are each alternately formed two or more in number. 
     Here, with reference to FIGS. 5 to  8 , the advantages of the multi-contact springs will now be explained in detail by comparing the characteristic of a multi-spring socket and that of a slot contact socket, both sockets using the multi-contact springs. 
     As illustrated in FIG. 5, the multi-contact socket using the multi-contact spring has a socket main body  29   a  having an opening portion  30   a . The multi-contact spring  21  is disposed within the opening  30   a  and forms a circle when viewed from the opening portion side. As a result of this, by a pin, not illustrated, being inserted into the multi-contact spring  21  via the opening portion  30   a , the pin and the multi-contact socket are electrically connected together. 
     As illustrated in FIG. 6, the slot contact socket has a socket main body  29   b  having an opening portion  30   b  and a tapered slot contact portion  40  disposed within the socket main body  29   b . As a result of this, by a pin, not illustrated, being inserted into a slot contact portion  40  via the opening portion  30   b , the pin and the slot contact socket are connected together. 
     FIG. 7 illustrates the results of comparison that is made between the slot contact socket (indicated in a dotted line in FIG. 7) and the multi-contact spring socket (indicated in a solid line in FIG. 7) in terms of the insertion force acting when the pin is inserted into the socket and the draw-off force acting when the pin is drawn off from the socket (in FIG. 7 the insertion force and draw-off forces have been called “an insert/draw-off force” as abbreviated). It is easily seen from FIG. 7 that the multi-contact spring socket is smaller. 
     FIG. 8 illustrates the results of comparison that is made between the slot contact socket (indicated in a dotted line in FIG. 8) and the multi-contact spring socket (indicated in a solid line in FIG. 8) in terms of the contact resistance that is produced when the pin is inserted into the socket. It is easily seen from FIG. 8 that the multi-contact spring socket is smaller in terms of the contact resistance. Namely, the multi-contact spring is smaller both in terms of the contact resistance and in terms of the insert/draw-off force. 
     The heating agent  23  is a thermit agent that is composed of, for example, a metal oxide powder such as iron oxide (Fe 2 O 3 ) and aluminum powder and makes a thermit reaction due to the heat generated from a lead wire  31  to thereby generate a high-temperature heat. It is to be noted that instead of using iron oxide (Fe 2 O 3 ) there may be used chromium (Cr 2 O 3 ), manganese oxide (MnO 2 ), etc. 
     Also, as the heating agent  23 , there may be used a mixture of metal powder of one kind selected from the group consisting of B, Sn, FeSi, Zr, Ti, and Al, metal oxide of one kind selected from the group consisting of CuO, MnO 2 , Pb 3 O 4 , PbO 2 , Fe 3 O 4 , and Fe 2 O 3 , and at least one kind of additive including alumina, bentonite, talc, etc. 
     Also, a compression spring  26 , or an elastic member, is disposed as an expansible and contractible elastic member between the heating agent casing  22  and groove portions  25  formed in the resin casing  17 . This compression spring  26  presses the heating agent casing  22  upward. 
     Also, the resin casing  17  has formed therein a concavities/convexities-like threaded portion  18  while the cap  19  has formed therein a concavities/convexities-like cap threaded portion  20 . It is thereby arranged that when the cap  19  has been mounted onto the resin casing  17 , the cap threaded portion  20  and the casing threaded portion  18  are screwed to each other. 
     Further, a groove portion  32  is formed in the form of a strip over an entire circumference of the heating agent casing  22 . Protrusion-like pawl portions  33   a ,  33   b , a claw portion to be lockingly engaged, are formed on a forward end portion of the resin casing  17 . The pawl portions  33   a ,  33   b  formed on the resin casing  17  are engaged with groove portions  32   a ,  32   b . These pawl portions  33   a ,  33   b  are arranged to stop the upward movement of the heating agent casing  22  due to the spring force of the compression spring  26 . 
     Next, the operation of the circuit breaker according to the embodiment, which has been constructed as described above, will be explained with reference to the drawings. 
     First, in FIGS. 1 and 3, ordinarily, the first bus bar  11  and the second bus bar  14  are electrically connected to each other via the multi-contact springs  21   a ,  21   b  and the heating agent casing  22 , whereby an electric current is supplied from a battery, not illustrated, to a load, not illustrated. 
     Next, when the vehicle collides with an obstacle or the like, or when the vehicle falls from a cliff or the like, an abnormality of the vehicle is sensed by a collision sensor, etc. By the sensing of the vehicle abnormality, an electric current flows into the ignition portion  24  through the lead wire  31 . 
     Then, the ignition portion  24  gets ignited due to the generation of heat due to the electric current. As a result, the heating agent  23 , which is a thermit agent, generates the heat of thermit reaction in accordance with the following reaction formula. 
     
       
         Fe 2 O 3 +2AL→Al 2 O 3 +2Fe+386.2 Kcal 
       
     
     Due to the heat of thermit reaction, the heating agent casing  22  is heated. Therefore, due to the generation of heat in the heating agent  23  and to the heat of the heating agent casing  22 , the pawl portions  33   a ,  33   b  that are in engagement with the groove portion  32  are heated to be melted. 
     As a result, as shown in FIG. 9, the compression spring  26  that has theretofore been compressed is expanded. As a result, while being slid on the multi-contact springs  21   a ,  21   b , the heating agent casing  22  having accommodated therein the ignition portion  24  is sprung up (in FIG. 9 a reference symbol  22 ′ represents the heating agent casing after it has been moved upward). 
     For this reason, the electrical connection between the heating agent casing  22  and the first bus bar  11  and the second bus bar  14  is rendered ineffective. Namely, it results that the first bus bar  11  and the second bus bar  14  are electrically out off, whereby the electric circuit of the vehicle is broken. 
     In this way, according to the circuit breaker of the embodiment, since each of the multi-contact springs  21   a ,  21   b  has a small resistance to contact, even when a large current passes therethrough, it is possible to lessen the generation of heat. Also, since the insert/draw-off forces thereof are small, even when the heating agent casing  22  is moved vertically, the heating agent casing  22  can easily rise due to a small sliding resistance of the multi-contact springs. 
     Namely, because of the sliding resistance of each multi-contact spring  21   a ,  21   b , the electric circuit of the vehicle can be broken reliably in a short time to make it possible to protect the relevant electric parts. Further, because of the use of the thermit reaction heat of the heating agent  23 , it is possible to provide the circuit breaker with a simple structure. 
     Also, because the external stress that has been applied to the first bus bar  11  and the second bus bar  14  can be absorbed by the multi-contact springs  21   a ,  21   b , the external stress ceases to be applied to the heating agent casing  22 . As a result of this, it is possible to enhance the reliability of the circuit breaker. Also, because of the use of the compression spring  26 , the circuit breaker becomes inexpensive, easy to design, and assemble. 
     Further, because the first bus bar  11  and the second bus bar  14  are being separated from the heating agent casing  22 , it is possible to enhance the assembling efficiency. Also, if insert molding the first bus bar  11  and the second bus bar  14  into the resin casing  17 , the number of assembling parts can be made smaller and the number of operational steps can be decreased. Also, since the cap  19  is fitted over the resin casing  17 , it does not happen that when the circuit is broken the heating agent casing  22  will be popped out. Also, there ceases to exist the possibility of a relevant person getting scorched, etc., due to the heat. 
     Second Embodiment 
     FIG. 10 illustrates a section of the circuit breaker according to a second embodiment. 
     In this embodiment, instead of mounting the multi-contact springs  21   a ,  21   b  onto the bus bar forward end portions  13 ,  16 , multi-contact springs  21   c ,  21   d  are mounted onto the heating agent casing  22 , for example. Further, alternatively, it may be arranged that one of the multi-contact springs  21   c ,  21   d  is mounted on a relevant one of the bus bar forward end portion  13 ,  16  while the other thereof is mounted on the heating agent casing  22 . 
     The present invention is not limited to the above described embodiment and modification. For example, regarding the multi-contact springs  21   a ,  21   b , only either one of them may be used. Also, the configuration of the multi-contact spring  21   a ,  21   b  is not limited to a circular arc configuration but may be triangular, square, or other configuration. Further, the width of the contact point portion  28   a ,  28   b , or the width of the slit portion  27   a ,  27   b  may be suitably selected. The direction of the slit portion  27   a ,  27   b  is not limited to the width direction but may be longitudinal or diagonal. The configuration of the slit portion  27   a ,  27   b  may be circular, an elliptic, triangular, polygonal, or other configuration. Regarding the pawl portions  33   a ,  33   b , only either one of them may be used. Also, the resin-made pawl portion may be fixed to the heating agent casing  22  and a groove may be formed in each of the first bus bar  11  and second bus bar  14 .