Patent Publication Number: US-2004057225-A1

Title: Fuse

Description:
[0001] The present application is based on Japanese Patent Application No. 2002-204108, which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to a fuse, and more particularly, to a blade type fuse which includes a fuse element having a fusible portion provided between a pair of flat plate terminal portions arranged in parallel, the fuse element being incorporated in an insulating housing.  
       [0004] 2. Related Art  
       [0005] A conventional fuse  1  as illustrated in FIG. 5 is a blade type fuse of low height which includes a fuse element  3  having a fusible portion  5  provided between a pair of flat plate terminal portions  4 ,  4  arranged in parallel, and an insulating housing  2  made of synthetic resin which contains the fuse element  3 .  
       [0006] The aforesaid flat plate terminal portions  4  are respectively formed in a substantially rectangular shape, and the aforesaid fusible portion  5  is provided between these flat plate terminal portions  4 ,  4  so as to laterally bridge their opposed inner edges  4   a ,  4   a.    
       [0007] The aforesaid insulating housing  2  which includes a pair of housing bodies  2   a ,  2   a  and an upper wall portion  2   c  mutually connecting upper ends of the housing bodies  2   a ,  2   a  is adapted to cover the inner edges  4   a  and upper edges  4   c  of the aforesaid flat plate terminal portions  4  and the aforesaid fusible portion  5 .  
       [0008] As shown in FIG. 6, on one side edge of a slit opening  6  formed at a lower end of the aforesaid insulating housing  2 , a flap  2   b  which is integrally formed with the housing through a thin-walled hinge  8  is continuously provided so as to freely rotate.  
       [0009] This flap  2   b  is rotated to a closed position in a state where the fuse element  3  has been inserted into the insulating housing  2  from the aforesaid slit opening  6 , and locked to locking projections  4   b  which are projected from the aforesaid inner edges  4   a  of the respective flat plate terminal portions  44  thereby to be held in the closed position.  
       [0010] In this manner, according to the fuse  1 , the flat plate terminal portions  4 ,  4  are held in the insulating housing  2 , and so, concentration of outer forces to the fusible portion  5  will be prevented.  
       [0011] However, in the above described conventional fuse  1 , the flap  2   b  of the insulating housing  2  is connected to one of the housing bodies  2   a  only through the thin-walled hinge  8  at its base end side, while its distal end side is just abutted against a lower end edge  7  of the other housing body  2   a.    
       [0012] Therefore, there has been such probability that in case where an outer force has been applied to the aforesaid flap  2   b  in a direction to open it, the flap  2   b  rides over the aforesaid locking projections  4   b  and becomes unable to protect the fusible portion  5 .  
       [0013] There has been another problem that the aforesaid insulating housing  2  has an open structure in section in which the upper ends of a pair of the housing bodies  2   a ,  2   a  are mutually connected through the upper wall portion  2   c , and so, it has been difficult to enhance strength of the insulating housing and to improve protecting performance for the fusible portion  5 .  
       SUMMARY OF THE INVENTION  
       [0014] In view of the above, an object of the present invention is to solve the above described problems, and to provide a favorable fuse in which deformation of a flap due to outer forces will be prevented and strength of an insulating housing can be enhanced.  
       [0015] The above described object of the invention is attained by a fuse comprising a fuse element which includes a fusible portion provided between inner edges of a pair of flat plate terminal portions arranged in parallel, and an insulating housing which includes a pair of housing bodies and an upper wall portion mutually connecting upper ends of the housing bodies, and covers the inner edges and upper edges of the aforesaid flat plate terminal portions and the aforesaid fusible portion, characterized in that on one side edge of a slit opening formed at a lower end of the aforesaid insulating housing, a flap which is integrally formed with the housing through a thin-walled hinge is continuously provided so as to freely rotate, and a distal end edge of the aforesaid flap is joined to the other side edge of the aforesaid slit opening, in a state where the aforesaid fuse element has been inserted into the insulating housing.  
       [0016] According to the above described structure, because the flap which is integrally formed at the lower end of one of the housing bodies through the thin-walled hinge is joined to the lower end edge of the other housing body at its distal end edge, the flap can be reliably held in a closed state.  
       [0017] Therefore, in case where an outer force has been applied to the aforesaid flap, the flap will not be displaced nor deformed so as to be easily opened, and the fusible portion can be reliably protected.  
       [0018] Moreover, because the slit opening formed at the lower end of the aforesaid insulating housing is reliably closed with the aforesaid flap which is joined at its distal end edge, the insulating housing will have a closed structure in section, and thus, strength of the insulating housing will be enhanced.  
       [0019] Further, the distal end edge of the aforesaid flap is preferably joined to the other side edge of the aforesaid slit opening by welding or by means of at least one locking pawl.  
       [0020] In this case, joining work for joining the distal end edge of the aforesaid flap to the other side edge of the aforesaid slit opening becomes easy, and productivity can be improved. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0021]FIG. 1 is a perspective view showing an exterior appearance of a fuse according to a first embodiment of the present invention;  
     [0022]FIG. 2 is a perspective view in section of the fuse as shown in FIG. 1.  
     [0023]FIG. 3 is a perspective view showing an exterior appearance of an essential part of a fuse according to a second embodiment of the invention.  
     [0024]FIG. 4 is a perspective view showing an exterior appearance of an essential part of a fuse according to a third embodiment of the invention.  
     [0025]FIG. 5 is a sectional view of a conventional fuse.  
     [0026]FIG. 6 is an enlarged sectional view of an essential part of the fuse as shown in FIG. 5. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0027] Now, an embodiment of the invention will be described  20  in detail, referring to the attached drawings.  
     [0028]FIG. 1 is a perspective view showing an exterior appearance of a fuse according to a first embodiment of the invention, and FIG. 2 is a perspective view in section of the fuse as shown in FIG. 1. It is to be noted that since a fuse element in a  25  fuse  10  of this first embodiment has substantially the same structure as the fuse element  3  as shown in FIG. 5, the same components are denoted with the same reference numerals, and their detailed description will be omitted.  
     [0029] The fuse  10  in this first embodiment is a blade type fuse of low height which includes, as shown in FIGS. 1 and 2, a fuse element  3  having a fusible portion  5  provided between a pair of flat plate terminal portions  4 ,  4  arranged in parallel, and an insulating housing  11  made of synthetic resin in a T-shape which contains the fuse element  3 .  
     [0030] The aforesaid insulating housing  11  which includes a pair of housing bodies  11   a ,  11   a  and an upper wall portion  11   c  mutually connecting upper ends of the housing bodies  11   a ,  11   a  is adapted to cover inner edges  4   a  and upper edges  4   c  of the aforesaid flat plate terminal portions  4 , and the aforesaid fusible portion  5 .  
     [0031] Moreover, on one side edge of a slit opening  16  formed at a lower end of the aforesaid insulating housing  11 , a flap  11   b  which is integrally formed with the housing through a thin-walled hinge  18  is continuously provided so as to freely rotate, as shown in FIG. 2.  
     [0032] This flap  11   b  is rotated to a closed position in a state where the fuse element  3  has been inserted into the insulating housing  11  from the aforesaid slit opening  16 , and locked to locking projections  4   b  which are projected from the aforesaid inner edges  4   a  of the respective flat plate terminal portions  4 .  
     [0033] Further, the distal end edge of the aforesaid flap  11   b  which is abutted against the other side edge  12  of the aforesaid slit opening  16  (the lower end edge of the other housing body  11   a ) is joined by ultrasonic welding, thermal welding or the like, as shown in FIG. 2.  
     [0034] Specifically, according to the fuse  10  in this first embodiment, the flap  11   b  which is integrally formed with one of the housing bodies  11   a  (a frontward one in the drawings) through the thin-walled hinge  18  is joined to the lower end of the other housing body  11   a  (a backward one in the drawings) at its distal end edge, and therefore, it is possible to reliably hold the flap  11   b  in the closed state.  
     [0035] Therefore, in case where an outer force has been applied to the aforesaid flap  11   b  in a direction to open it, the flap  11   b  will not be displaced nor deformed so as to be easily opened, and the aforesaid fusible portion  5  can be reliably protected.  
     [0036] Moreover, because the slit opening  16  formed at the lower end of the aforesaid insulating housing  11  is reliably closed with the aforesaid flap  11   b  which is joined at its distal end edge, the insulating housing  11  will have a closed structure in section, and thus, strength of the insulating housing will be enhanced.  
     [0037] Consequently, by employing the aforesaid insulating housing  11  which has the enhanced strength, according to the fuse  10  in this first embodiment, protecting performance for the aforesaid fusible portion  5  can be enhanced.  
     [0038] Further, the structure including the fuse element, housing bodies, flap, and so on in the fuse according to the invention is not restricted to the structure in the above described embodiment, but it is needless to say that various forms can be employed on the basis of concept of the invention.  
     [0039]FIG. 3 is a perspective view showing an exterior appearance of an essential part of a fuse according to a second embodiment of the invention.  
     [0040] A fuse  20  in this second embodiment is a blade type fuse of low height which includes a fuse element  3  having a fusible portion  5  provided between a pair of flat plate terminal portions  4 ,  4  arranged in parallel, and an insulating housing  21  made of synthetic resin which contains the fuse element  3 , similarly to the fuse  10  in the first embodiment as shown in FIG. 1.  
     [0041] As shown in FIG. 3, on one side edge of a slit opening formed at a lower end of the aforesaid insulating housing.  21 , a flap  21   b  which is integrally formed with the housing through a thin-walled hinge  28  is continuously provided so as to freely rotate, and a locking pawl  23  is projected from a distal end edge  22  of the flap  21   b.    
     [0042] The aforesaid flap  21   b  is rotated to a closed position in a state where the fuse element  3  has been inserted into the insulating housing  21  from the slit opening, and locked to the locking projections  4   b  which are projected from the aforesaid inner edges  4   a  of the respective flat plate terminal portions  4 .  
     [0043] Moreover, the distal end edge  22  of the aforesaid flap  21   b  is joined in such a manner that the aforesaid locking pawl  23  is locked to the other side edge  24  of the above described slit opening (the lower end edge of the other housing body  21   a ) Therefore, also with the fuse  20  in this second embodiment, the protecting performance for the fusible portion  5  of the fuse element  3  which has been inserted into the insulating housing  21  can be enhanced, in the same manner as with the fuse  10  in the above described first embodiment.  
     [0044]FIG. 4 is a perspective view showing an exterior appearance of an essential part of a fuse according to a third embodiment of the invention. An insulating housing  31  of a fuse  30  according to this third embodiment is continuously provided, on one side edge of a slit opening formed at its lower end as shown in FIG. 4, with a flap  31   b  which is integrally formed with the housing through a thin-walled hinge  38  so as to freely rotate, and a pair of locking pawls  33 ,  33  are projected from a distal end edge  32  of the flap  31   b.    
     [0045] The aforesaid flap  31   b  is rotated to a closed position in a state where the fuse element  3  has been inserted into the insulating housing  31  from the slit opening, and locked to the locking projections  4   b  which are projected from the aforesaid inner edges  4   a  of the respective flat plate terminal portions  4 .  
     [0046] Moreover, the distal end edge  32  of the aforesaid flap  31   b  is joined in such a manner that a pair of the aforesaid locking pawls  33 ,  33  are locked to the other side edge  34  of the slit opening (the lower end edge of the other housing body  31   a ).  
     [0047] Therefore, also with the fuse  30  in this third embodiment, the protecting performance for the fusible portion  5  of the fuse element  3  which has been inserted into the insulating housing  31  can be enhanced, in the same manner as with the fuse  20  in the above described second embodiment.  
     [0048] Further, because the aforesaid locking pawls  33  are provided in a pair, it is possible to obtain a larger joining force than a locking force by means of the locking pawl  23  in the above described second embodiment.  
     [0049] It is to be noted that the flaps  21   b ,  31   b  according to the above described second and third embodiments can be joined only by locking the aforesaid locking pawls  23 ,  33  to the aforesaid side edges  24 ,  34  thereby to eliminate necessity of subsequent steps such as welding works, and assembling workability will be enhanced.  
     [0050] As described herein above, according to the fuse of the present invention, the flap which is integrally formed at the lower end of one of the housing bodies through the thin-walled hinge is joined to the lower end edge of the other housing body at its distal end edge, and accordingly, the flap can be reliably held in the closed state.  
     [0051] Therefore, in case where an outer force has been applied to the aforesaid flap, the flap will not be displaced nor deformed so as to be easily opened, and the fusible portion can be reliably protected.  
     [0052] Moreover, because the slit opening formed at the lower end of the aforesaid insulating housing is reliably closed with the aforesaid flap which is joined at its distal end edge, the insulating housing will have a closed structure in section, and thus, strength of the insulating housing will be enhanced.  
     [0053] Consequently, by employing the aforesaid insulating housing which has the enhanced strength, according to the fuse of the invention, the protecting performance for the aforesaid fusible portion can be enhanced.