Patent Publication Number: US-6666722-B2

Title: Fuse holder

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to copending U.S. Patent Application Ser. Nos. 10/080,151 and 10/080,154, both filed on Feb. 19, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention belongs to a field of fuse holder, into which a blade type fuse, with blade terminals protruding from its body, is fitted. 
     2. Related Art 
     A fuse fitting device, into which a blade type fuse is fitted, is known. This device comprises a block of synthetic resin, and connecting terminals, which are inserted from below into a chamber in the block and fitted to a lance of the block. When this fuse fitting device is to be used, electric wires are connected to the connecting terminals, these connecting terminals are inserted into the chamber of the block and fitted to the lance, a fuse is inserted from above into the chamber of the block, and the blade terminals of the fuse are fitted into the connecting terminals to make connection (for example, refer to Japanese Patent unexamined publication gazette Heisei 6-150806). 
     When a plurality of fuses are to be fitted into this fuse fitting device, a new block must be newly designed whenever the combination of fuses is modified. It is inevitable to produce a mold for the block in each occasion, and in turn, the production of the fuse fitting device is costly. 
     SUMMARY OF THE INVENTION 
     The present invention was made in view of these points, and one objective of the invention is to propose a fuse holder wherein a holder housing is combined with contacts, mount this fuse holder on a printed circuit board, load the printed circuit board in a casing or the like and produce a fuse fitting device, and easily realize any combination of fuses and reduce the production cost of the fuse fitting device. Other objectives include to reduce the production cost by adopting fork-shaped contacts, and to guarantee high performance of the fuse fitting device by supporting these contacts by the holder housing and preventing the contacts from being pried. 
     To accomplish these objectives, the present invention is a fuse holder, into which a blade type fuse, with blade terminals protruding from the body thereof, is fitted, said fuse holder comprising a holder housing having wide walls at the front and the rear and narrow walls on the right and the left and forming, with these walls, a chamber, which will hold the blade terminals of a fuse inserted from the top side and at least a part of the body of the fuse, and two contacts, each of which has an intermediate part fixed to the holder housing, a connecting part, at one end, extending into the chamber to fit with a blade terminal, and a leg, at the other end, extending out of the holder housing to be soldered or press-fitted onto a printed circuit board. 
     When a fuse is fitted into this fuse holder, the blade terminals and at least a part of the body of the fuse will be held in the chamber of the holder housing and the blade terminals will be fitted into the connecting parts of the contacts. When the legs of the contacts are soldered or press-fitted onto a printed circuit board, the fuse holder with the fuse being fitted into the holder will be mounted on the printed circuit board. When conductive parts such as electric wires are connected to the pattern of the printed circuit board, the fuse will be electrically connected to the conductive parts. When the printed circuit board is loaded into a casing or the like, a fuse fitting device will be produced. When this fuse holder is used, a fuse fitting device can be made for any combination of fuses without newly designing a block. Hence the production cost is reduced. To complete a fuse fitting device, the fuse holder may be mounted onto the printed circuit board before fitting a fuse into the fuse holder. 
     Accordingly, with the use of the fuse holder of the present invention, a fuse fitting device can be produced for any combination of fuses without newly designing a block, and the production cost of the fuse fitting device can be reduced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the first embodiment of the fuse holder seen from the top side thereof. 
     FIG. 2 is a perspective view of the first embodiment of the fuse holder seen from the bottom side thereof. 
     FIG. 3 is a front view of the first embodiment of the fuse holder. 
     FIG. 4 is a plan view of the first embodiment of the fuse holder. 
     FIG. 5 is a bottom view of the first embodiment of the fuse holder. 
     FIG. 6 is a vertical sectional view of the first embodiment of the fuse holder cut in both the left wall and the right wall thereof. 
     FIG. 7 is a vertical sectional view of the first embodiment of the fuse holder cut in both the front wall and the rear wall thereof. 
     FIG. 8 is a diagram corresponding to FIG.  6  and shows the first embodiment of the fuse holder when a fuse is fitted into it. 
     FIG. 9 is a diagram corresponding to FIG.  7  and shows the first embodiment of the fuse holder when a fuse is fitted into it. 
     FIG. 10 is a perspective view of the second embodiment of the fuse holder seen from the top side thereof. 
     FIG. 11 is a perspective view of the second embodiment of the fuse holder seen from the bottom side thereof. 
     FIG. 12 is a front view of the second embodiment of the fuse holder. 
     FIG. 13 is a plan view of the second embodiment of the fuse holder. 
     FIG. 14 is a bottom view of the second embodiment of the fuse holder. 
     FIG. 15 is a vertical sectional view of the second embodiment of the fuse holder cut in both the left wall and the right wall thereof. 
     FIG. 16 is a vertical sectional view of the second embodiment of the fuse holder cut in both the front wall and the rear wall thereof. 
     FIG. 17 is a diagram corresponding to FIG.  15  and shows the second embodiment of the fuse holder when a fuse is fitted into it. 
     FIG. 18 is a diagram corresponding to FIG.  16  and shows the second embodiment of the fuse holder when a fuse is fitted into it. 
     FIG. 19 is a vertical sectional view of the third embodiment of the fuse holder cut in both the front wall and the rear wall thereof. 
     FIG. 20 is a vertical sectional view of the fourth embodiment of the fuse holder cut in both the left wall and the right wall thereof. 
     FIG. 21 is a bottom view of the fourth embodiment of the fuse holder. 
     FIG. 22 is a vertical sectional view of the fourth embodiment of the fuse holder cut in both the front wall and the rear wall thereof. 
     FIG. 23 is a vertical sectional view of the fifth embodiment of the fuse holder cut in both the left wall and the right wall thereof. 
     FIG. 24 is a bottom view of the fifth embodiment of the fuse holder. 
     FIG. 25 is an enlarged view showing the leg of the contact of the sixth embodiment of the fuse holder. 
     FIG. 26 is an enlarged view showing a variation of the leg of the contact of the sixth embodiment of the fuse holder. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
     In the following, some embodiments of the fuse holder according to the present invention will be described. A fuse to be fitted into this fuse holder is a blade type fuse  200 , as shown in FIG.  8  and FIG.  9  and FIG.  17  and FIG. 18, with two blade terminals  220  protruding from the body  210  thereof. These fuses  200  have been standardized. The larger fuse  200  shown in FIG.  8  and FIG. 9 is of the maxi type, and the smaller fuse  200  shown in FIG.  17  and FIG. 18 is of the mini type. 
     FIG.  1  through FIG. 7 show the first embodiment fuse holder  100 . A fuse  200  of the maxi type is fitted into this fuse holder  100 . The fuse holder  100  comprises a holder housing  110  being made of an insulator and two contacts  120  being made of a conductor and fitted onto the holder housing  110 . 
     The holder housing  110  has wide walls  111 ,  112  at the front and the rear, and narrow walls  113 ,  114  on the left and the right thereof. A chamber  115 , which is through from the top  110   a  to the bottom  110   b  of the holder housing  110 , is formed on the inner sides of the front wall  111 , the rear wall  112 , the left wall  113  and the right wall  114 . The front, rear, left and right herein are used for convenience to indicate relative positional relationships. Accordingly, these directions are not related to the orientations of a printed circuit board  300 , onto which the fuse holder  100  is to be mounted, and the casing, into which the printed circuit board  300  is to be loaded. When a fuse  200  is inserted into the holder housing  110  from the top side thereof, the blade terminals  220  of the fuse  200  and at least a part of the body  210  thereof will be held in the chamber  115 . A portion of the holder housing  110  from a point between the top  110   a  and the bottom  110   b  and to the top  110   a  overhangs in the direction of alignment of the blade terminals  220 . The body  210  of the fuse  200  is held by a horizontal wall  110   c , which is inside the above-mentioned overhanging part. 
     A rib  211  is formed on each side end of the body  210  of the fuse  200  in parallel with the extending direction of the blade terminals  220 . U-shaped supporting parts  116 , into which the ribs  211  of the body  210  of the fuse  200  are to be fitted, are provided in the tops of the left wall  113  and the right wall  114  of the holder housing  110 . 
     Slits  117 , into which the side edges  221  of the blade terminals  220  are to be fitted, are provided in the left wall  113  and the right wall  114  of the holder housing  110 . 
     Two bosses  118 ,  119  are provided on the bottom  110   b  of the holder housing  110 . When seen from the bottom, the bosses  118 ,  119  are arranged asymmetrically relative to each other in relation to a line L, which runs between the front wall  111  and the rear wall  112  approximately in parallel to these walls. 
     An intermediate part  121  of each contact  120  is fixed to the bottom  110   b  of the holder housing  110 . A fork-shaped connecting part  122  is provided on one end of the contact  120  to extend towards the inside of the chamber  115 . This connecting part  122  is formed approximately into a U shape, and its two branches  122   a  are arranged to expand towards the front wall  111  and the rear wall  112  to fit with the blade terminal  220  with a certain contact pressure. A leg  123  is provided on the other end of the contact  120  to extend out of the holder housing  110 . This leg  123  is soldered or press-fitted onto a printed circuit board  300 . 
     The intermediate part  121  of the contact  120  is press-fitted into a space between the wall  111  and the wall  112  at the bottom  110   b  of the holder housing  110 . 
     The leg  123  of the contact  120  is forked into two branches. In other words, it has two ends. 
     The clearances t between the connecting part  122  and the front wall  111  and the rear wall  112  of the holder housing  110  are set in such a way that they allow deformation of the connecting part  122  while limiting its excessive deformation. In other words, the clearances t are provided not to hinder expansion of the two branches  122   a  of the connecting part  122  when they are properly pushed by the blade terminal  220  to expand towards the front wall  111  and the rear wall  112 . Moreover, the clearances t are provided to hold and prevent excessive deformation of the two branches  122   a  when they are pried by the blade terminal  220 . 
     Accordingly, in the case of the above-mentioned first embodiment, as shown in FIG.  8  and FIG. 9, when a fuse  200  is fitted into the fuse holder  100 , the blade terminals  220  and at least a part of the body  210  will be received in the chamber  115  of the holder housing  110 , and the blade terminals  220  will be fitted into the connecting parts  122  of the contacts  120 . When the legs  123  of the contacts  120  are soldered or press-fitted onto the printed circuit board  300 , the fuse holder  100  with the fuse  200  fitted in position will be mounted on the printed circuit board  300 . When conductive parts such as electric wires are connected to the pattern of the printed circuit board  300 , the fuse  200  will be electrically connected to the conductive parts. When the printed circuit board  300  is loaded in a casing or the like, a fuse fitting device will be produced. With the use of this fuse holder  100 , a fuse fitting device can be produced for any combination of fuses  200  without newly designing a block. Thus the production cost is reduced. When a fuse fitting device is produced, fuses  200  may be fitted into the fuse holders  100  after the fuse holders  100  have been mounted on a printed circuit board  300 . 
     The present invention does not limit the configuration of the connecting part of the contact. For example, the present invention includes embodiments wherein the connecting part is formed with a coiled spring and the contact pressure between the contact and the blade terminal is secured by the coiled spring. Among the embodiments of the present invention, in the case of the above-mentioned first embodiment, the connecting part  122  of the contact  120  is formed into a fork shape that can expand towards the front wall  111  and the rear wall  112 , and the clearances t between the connecting part  122  and the front wall  111  and the rear wall  112  of the holder housing  110  allow deformation of the connecting part  122  while limiting its excessive deformation. With these arrangements, as the contact  120  is fork-shaped, the production cost is lower in comparison with a case wherein contacts with coiled spring ends are used. When the connecting part  122  of the contact  120  is deformed, the connecting part  122  will be restrained from excessive deformation by the front wall  111  and the rear wall  112  of the holder housing  110 , and in turn, the connecting part  122  will be prevented from being pried by the blade terminal  220 . 
     The present invention includes embodiments wherein the holder housing is not provided with any supporting part. Among the embodiments of the present invention, in the case of the above-mentioned first embodiment, supporting parts  116  are provided on the tops of the left wall  113  and the right wall  114  of the holder housing  110 . With this arrangement, fitting the ribs  211  into the supporting parts  116  will accurately determine the relative positions of the fuse  200  and the fuse holder  100  to each other, and the blade terminals  220  will be prevented from prying the connecting parts  122 . Moreover, the fuse  200  will be held more securely in the fuse holder  100 . 
     The present invention includes embodiments wherein the holder housing is not provided with any slit. Among embodiments of the present invention, in the case of the above-mentioned first embodiment, the holder housing  110  is provided with slits  117 . With this arrangement, fitting the side edges  221  into the slits  117  will accurately determine the relative positions of the fuse  200  and the fuse holder  100  to each other, and the blade terminals  220  will be prevented from prying the connecting parts  122 . Moreover, the fuse  200  will be held more securely in the fuse holder  100 . 
     The present invention does not limit the structure for fixing the intermediate part of the contact to the holder housing. Among the embodiments of the present invention, in the case of the above-mentioned first embodiment, the intermediate part  121  of the contact  120  is press-fitted into a space between the wall  111  and the wall  112  at the bottom  110   b  of the holder housing  110 . With this arrangement, the production method is easy to execute among the production methods wherein the contacts  120  and the holder housing  110  are separately formed and then combined together. 
     The present invention does not limit the configuration of the leg  123  of the contact  120 . Among the embodiments of the present invention, in the case of the above-mentioned first embodiment, the leg  123  of the contact  120  is formed into two branches. With this arrangement, the contact  120  will be connected to the printed circuit board  300  at two points, and defective connection will hardly occur. 
     The present invention includes embodiments wherein the holder housing is not provided with any boss. Among the embodiments of the present invention, in the case of the above-mentioned first embodiment, the bottom  110   b  of the holder housing  110  is provided with two bosses  118 ,  119  in positions that are asymmetric to each other in relation to a line L, which runs, when seen from the bottom, between the front wall  111  and the rear wall  112 . With this arrangement, when holes corresponding to the bosses  118 ,  119  are made in advance in the printed circuit board  300 , mounting in wrong orientation of the fuse holder  100  on the printed circuit board  300  will be prevented. 
     In the following, other embodiments will be described. The description of the first embodiment will apply in its entirety as the description of each embodiment, and the same reference character will be used for the same member, and only parts that differ in construction from those of the first embodiment will be described. 
     FIG.  10  through FIG. 18 show the second embodiment fuse holder  100 . A mini-type fuse  200  is fitted into this fuse holder  100 . This fuse holder  100  differs from the first embodiment fuse holder  100  in the following points. As the fuse  200  has no ribs  211 , the holder housing  110  is not provided with any supporting part  116 . The leg  123  of the contact  120  is not forked into two branches. However, the embodiments of the fuse holder  100 , into which such a mini-type fuse  200  is fitted, include embodiments wherein the leg  123  of the contact  120  is forked into two branches. 
     FIG. 19 shows the third embodiment fuse holder. The third embodiment differs from the first embodiment in the method of fixing the contacts  120  to the holder housing  110 . In the third embodiment, the intermediate parts  121  of the contacts  120  are enveloped-cast in the holder housing  110 . Enveloped-casting means that a material in a molten state adheres to and envelops an object and then solidifies over the object. In production of the fuse holder  100 , contacts  120  are set in the mold of the holder housing  110 , then the material is filled in the mold to form the holder housing  110 . In this way, relative positions of the contacts  120  and the holder housing  110  will be determined with high precision to each other. 
     FIG.  20  through FIG. 22 show the fourth embodiment fuse holder. The fourth embodiment differs from the first embodiment in the method of fixing the contacts  120  to the holder housing  110 . In the fourth embodiment, the intermediate part  121  of the contact  120  is enveloped-cast in an insert  125  and this insert  125  is fitted into a space among the walls  111  through  114  at the bottom  110   b  of the holder housing  110 . With this arrangement, molding of the holder housing  110  and enveloped-casting of inserts  125  are made separately, and each can be done under optimal conditions. 
     FIG.  23  and FIG. 24 shows the fifth embodiment fuse holder. The fifth embodiment differs from the fourth embodiment in the configuration of the insert. The two inserts  125  corresponding to the respective contacts  120  are coupled by a bridge  126 . With this arrangement, inserting the inserts  125  having the contact  120  into the holder housing  110  can be done by a single operation. 
     The present invention does not limit the material of the insert  125 . However, when the insert  125  is formed of a material, of which heat resistance is superior to that of the holder housing  110 , the heat resistance of the holder housing  110  will not pose any problem even if the inserts  125  are subjected to heat of soldering. Hence the holder housing  100  can be made of a more inexpensive material. 
     FIG.  25  and FIG. 26 show the sixth embodiment fuse holder. In this embodiment, a protrusion  123   a  is formed in the leg  123  of the contact  120 . This protrusion  123   a  is also called a clinch. The protrusion  123   a  may be formed, as shown in FIG. 25, by bending the leg  123  sidewise to form a V shape, or as shown in FIG. 26, by making a part of the leg  123  protrude sidewise. With this arrangement, when the leg  123  of the contact  120  is to be tacked onto a printed circuit board  300  before soldering, fitting the leg  123  of the contact  120  into a hole in the printed circuit board  300  will generate a greater fitting force at the protrusion  123   a . Thus tacking can be done reliably. 
     The present invention does not limit the color of the holder housing  110 . However, if the holder housing  110  has the same color as that of the body  210  of the fuse  200 , the proper fuse  200  for the fuse holder  100  can be identified easily. 
     The present invention includes embodiments that combine features of the above-mentioned embodiments. 
     With the description of these embodiments, the first fuse holder, which was described in the summary of the invention, has been fully disclosed. Moreover, with the description of these embodiments, the second fuse holder through the thirteenth fuse holder, which will be described below, have been fully explained. 
     The second fuse holder is a fuse holder as recited in the above-mentioned first fuse holder, wherein the connecting part of the contact is formed into a fork shape, which can be expanded towards the front wall and the rear wall of the holder housing, and the clearances between the connecting part and the front wall and the rear wall are set in such a way that they allow deformation of the connecting part while limiting its excessive deformation. With this arrangement, as the contact has a fork shape, the production cost is lower than that of a contact having a coiled spring at the top end thereof. When the connecting part of the contact is deformed, the connecting part will be prevented from excessive deformation by the front wall and the rear wall of the holder housing, thus the connecting part will be prevented from being pried by the blade terminal. Hence a high level of performance of the fuse fitting device can be guaranteed. 
     The third fuse holder is a fuse holder as recited in the above-mentioned first or second fuse holder, wherein U-shaped supporting parts, into which ribs provided in side ends of the body of the fuse are to be fitted, are provided on the tops of the left wall and the right wall of the holder housing. With this arrangement, fitting the ribs in the supporting parts will accurately determine the relative positions of the fuse and the fuse holder to each other, the blade terminals will be prevented from prying the connecting parts, and a higher level of performance of the fuse fitting device can be guaranteed. Moreover, the fuse will be held more securely in the fuse holder. 
     The fourth fuse holder is a fuse holder as recited in any one of the above-mentioned first through third fuse holders, wherein the left wall and the right wall of the holder housing are provided with a slit, into which a side edge of the blade terminal is fitted. With this arrangement, fitting the side edges into the slits will accurately determine the relative positions of the fuse and the fuse holder to each other, the blade terminals will be prevented from prying the connecting parts, and a higher level of performance of the fuse fitting device can be guaranteed. Moreover, the fuse will be held more securely in the fuse holder. 
     The fifth fuse holder is a fuse holder as recited in any one of the above-mentioned first through fourth fuse holders, wherein the intermediate part of the contact is press-fitted into a space between the walls at the bottom of the holder housing. With this arrangement, the production method is easy to execute among the production methods wherein the contacts and the holder housing are separately formed and then combined together. Thus the fuse holder can be produced with efficiency. 
     The sixth fuse holder is a fuse holder as recited in any one of the above-mentioned first through fourth fuse holders, wherein the intermediate parts of the contacts are enveloped-cast in the holder housing. With this arrangement, the relative positions of the contacts and the holder housing can be determined with high precision to each other. 
     The seventh fuse holder is a fuse holder as recited in any one of the above-mentioned first through fourth fuse holders, wherein the intermediate part of the contact is enveloped-cast in an insert and this insert is fitted into a space among the walls at the bottom of the holder housing. With this arrangement, molding of the holder housing and enveloped-casting of inserts are made separately, and each can be done under optimal conditions. 
     The eighth fuse holder is a fuse holder as recited in the above-mentioned seventh fuse holder, wherein two inserts are coupled together. With this arrangement, inserting the inserts having the contact into the holder housing can be done by a single operation. Thus the efficiency of the assembly can be enhanced. 
     The ninth fuse holder is a fuse holder as recited in the above-mentioned seventh or eighth fuse holder, wherein the insert is formed of a material, of which heat resistance is superior to that of the holder housing. With this arrangement, the heat resistance of the holder housing will not pose any problem even if the insert is subjected to heat of soldering. Hence the holder housing can be made of a more inexpensive material. 
     The tenth fuse holder is a fuse holder as recited in any one of the above-mentioned first through ninth fuse holders, wherein the leg of the contact is forked into two branches. With this arrangement, the contact will be connected to the printed circuit board at two points, and defective connection between the fuse holder and the printed circuit board can be prevented. 
     The eleventh fuse holder is a fuse holder as recited in any one of the above-mentioned first through tenth fuse holders, wherein a protrusion is formed in the leg of the contact. With this arrangement, when the leg of the contact is to be tacked onto a printed circuit board before soldering, fitting the leg of the contact into a hole in the printed circuit board will generate a greater fitting force at the protrusion. Thus tacking will be done reliably. 
     The twelfth fuse holder is a fuse holder as recited in any one of the above-mentioned first through eleventh fuse holders, wherein the bottom of the holder housing is provided with two bosses in positions that are asymmetric to each other in relation to a line, which runs, when seen from the bottom, between the front wall and the rear wall approximately in parallel with these walls. With this arrangement, when holes corresponding to the bosses are made in advance in the printed circuit board, mounting, in wrong orientation, of the fuse holder on the printed circuit board will be prevented. 
     The thirteenth fuse holder is a fuse holder as recited in any one of the above-mentioned first through twelfth fuse holders, wherein the holder housing has the same color as that of the body of the fuse. With this arrangement, the proper fuse for the fuse holder can be identified easily.