Abstract:
A relay including a coil, a yoke having a first yoke leg and a second yoke leg, a first connector terminal being electrically connected to a first contact terminal, a second connector terminal being electrically connected to a second contact terminal via a movable contact terminal, and a fuse having, a first end portion and a second end portion. The first end portion and the second end portion of the fuse being fixedly and directly connected to the first contact terminal and the second contact terminal, respectively.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a relay having a fuse fixedly and directly connected to the relay.  
         [0003]     2. Description of the Background Art  
         [0004]     More and more electronic devices are mounted on vehicles to enhance fuel economy, anti-pollution measures, drivability, comfortableness in an interior space, etc. Thus, there has been an increase in the number of relays and fuses that are provided in a vehicle fuse box in order to control and protect electrical components. As such, the vehicle fuse boxes become increasingly larger and more complex.  
         [0005]     A fuse protects a circuit against damage caused by a short circuit or overcurrent. The link in the fuse will melt and burn in half to stop excess current and further circuit damage. A relay is an electrically operated switch. It allows a small dash switch to control another circuit by remote control, whereby the control comes from a distant point in the circuit.  
         [0006]      FIG. 1  is an illustration of a conventional vehicle fuse box  1  that has a plurality of fuse receptacles  3  and relay receptacles  5  for receiving fuses  7  and relays  9 , respectively, therein. As can be appreciated, because of the increasing electrical complexity of modern vehicles, the fuse box  1 , as noted above, becomes increasingly larger.  
         [0007]     DE3209915 and U.S. Pat. No. 6,320,486 each disclose, with reference to  FIGS. 2 and 3 , respectively, a relay  11  that has two additional connector tabs  13 ,  15  for removably receiving a melt plugable fuse  17 . The arrangements shown in  FIGS. 2 and 3  reduce the size of the conventional fuse box  1  because the fuse  17  is able to be plugged directly onto the relay  11 , and thus the number of fuse receptacles  3  can be reduced. However, because the relay  11  is designed to use conventional type melt plugable fuses  17 , a housing (not shown) of the relay  11  must take into consideration the dimensions of the fuse  17 , and thus, a size of the relay  11  is in fact larger than conventional relays  9 .  
         [0008]     More importantly, because the melt plugable fuses  17  are inserted into the connector tabs  13 ,  15 , heat is generated at contact points  19 . In addition, because of current, the contact points  19  relax and degrade and therefore, even more heat is generated. Typically, approximately 1-1.5 watts of heat can be generated at each contact point.  
         [0009]     For example, a typical vehicle fuse box  1  has approximately 20 relays and 20 fuses, whereby the fuses each have two contact points and the relays each have 4 contact points. Thus, there are 120 contact points that can generate 120-180 watts of heat. Because of the design of the relay  11  of the prior art, as shown in  FIGS. 2 and 3 , the generated heat is even more so concentrated in a smaller area on a fuse box than the conventional fuse box  1 .  
         [0010]     Furthermore, the prior art devices are prone to operator error. For example, if an operator inserts a 40 amp fuse into relay that is rated for 20 amps, the wrongly inserted fuse provides no protection for the relay or the circuit elements associated therewith, which can thus lead to the relay igniting and burning.  
       SUMMARY OF THE INVENTION  
       [0011]     It is therefore an object of the present invention to provide a universal protected relay that generates less heat and is able to be designed in a compact size. The relay includes a coil, a yoke having a first yoke leg and a second yoke leg, a first connector terminal being electrically connected to a first contact terminal, a second connector terminal being electrically connected to a second contact terminal via a movable contact, and a fuse having a first end portion and a second end portion. The first end portion and the second end portion of the fuse are fixedly and directly connected to the first contact terminal and the second contact terminal, respectively.  
         [0012]     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:  
         [0014]      FIG. 1  is a schematic illustration of a conventional vehicle fuse box;  
         [0015]      FIGS. 2 and 3  are illustrations of a prior art relay unit;  
         [0016]      FIGS. 4 and 5  are perspective views of a fuse linked relay according to a preferred embodiment of the present invention;  
         [0017]      FIG. 6  is a perspective view of the fuse linked relay showing a thermally insulated wall portion according to a preferred embodiment of the present invention;  
         [0018]      FIG. 7  is a perspective view of a housing being provided on the fuse linked relay according to a preferred embodiment;  
         [0019]      FIG. 8  is a top view of the fuse linked relay of  FIG. 7 ; and  
         [0020]      FIG. 9  is a perspective view of a fuse linked relay according to an alternate embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0021]     Referring to  FIGS. 4 and 5  there is shown a fuse linked relay  30  that includes a base  32  that is made of an insulating material, on which are arranged a magnet system with a coil  34 , a core  36  being arranged inside the coil  34 , and a L-shaped yoke  38  with a first yoke leg  40  and a second yoke leg  42 . An axis of the coil  34  is essentially perpendicular to a primary plane of the base  32 .  
         [0022]     The core  36  is connected to the first yoke leg  40 . Coil terminals  44  are electrically connected to the coil  34  to energize the coil  34  by a remote switch (not shown). A connector terminal  46  is electrically connected to a contact terminal  52  and a connector terminal  48  is electrically connected to a movable contact terminal  50  that contacts a contact terminal  54  when the coil  34  is energized.  
         [0023]     Between the contact terminals  52  and  54  a fuse  56  is arranged so that the fuse  56  is in series with the contact terminals  52  and  54 , and thus in series with the connector terminals  46  and  48 . The fuse  56  can be a melt type fuse, a resettable fuse, such as a polymeric PTC (Positive Temperature Coefficient) resettable fuse, a circuit breaker, a thermistor, or any type of circuit protecting device.  
         [0024]     The fuse  56  shown in  FIGS. 4 and 5  has a fuse link  58 , which breaks (melts) depending on the current passing there through. For example, the fuse link  58  can be rated for 15 amps, 30 amps, etc. The fuse  56  is directly and non-removably connected to the contact terminals  52 ,  54  by, for example, welding, brazing, or riveting ends  60 ,  62  of the fuse  56  to the contact terminals  52 ,  54 , respectively. In addition, bottom portions of the ends  52 ,  54  can be anchored to the base  32  by epoxy, press fit, or staking.  
         [0025]     Because the ends  60 ,  62  of the fuse  56  are directly and non-removably connected to the contact terminals  52 ,  54 , no heat is generated. Whereas, as noted above, approximately 3 watts of heat are generated at the contact points of the plugable fuse of the prior art. Thus, the present invention significantly reduces the amount of heat being generated by the fuse linked relay  30 . For example, in a vehicle having 20 fuse linked relays  30  in a fuse box, the amount of heat that is generated is approximately 80 watts. In contrast thereto, as previously noted, the fuse and relay combinations of the prior art generate 120-180 watts of heat or more.  
         [0026]     In a preferred embodiment, the fuse linked relay  30  includes a thermally insulated wall  64  that is provided between the coil  34  and the fuse  56 . The thermally insulated wall  64  reduces thermal derating effects between the coil  34  and the fuse  56 . The thermally insulated wall  64  can be integrally molded with the housing  66 , as shown in  FIG. 6 , or can be a separate element that is provided between the coil  34  and the fuse  56 .  
         [0027]      FIGS. 7 and 8  show, in a preferred embodiment, the housing  66  encapsulating the coil  34 , the yoke  38 , and the fuse  56  such that a bottom edge  68  of the housing  66  of the fuse linked relay  30  contacts a circumferential edge of the base  32 . The housing  66  can be attached to the base  32  by, for example, snap fit, or by any other known method. The housing  66  can be molded as one-piece or can be molded in separate sections, e.g., one section to cover the yoke  38  and coil  34  and another section to cover the fuse  58 .  
         [0028]     In a further embodiment, the housing  66  can be made of a transparent material or can be formed so as to have a transparent window  70 , which can be formed on the housing  66  by a two shot molding process or can be snap fit into the housing  66 . The transparent window  70  is preferably provided, for example, on a top side  72  of the housing  66 , so that the fuse link  58  can viewed to determine whether or not the fuse link  58  has been disconnected, e.g. blown. It is noted that the transparent window  70 , or a plurality of transparent windows  70 , can be provided anywhere on the housing  66 , depending on the application of the fuse linked relay  30 . In addition, the transparent window  70  can be smooth or textured and can also be colored to follow the standard color association of fuses. The housing  66  can also further include an aperture (not shown) for enabling access to manually reset the fuse  56 .  
         [0029]      FIG. 9  illustrates the fuse linked relay  30  according to an alternate embodiment, whereby the fuse linked relay  30  has its coil terminals  74  and connector terminals  76  formed as PCB (Printed Circuit Board) leads, which can be soldered, brazed, or welded, to, for example, a fuse box or a circuit board. In addition,  FIG. 9  also illustrates a resettable type fuse  76 , in this example, a polymeric PTC resettable fuse.  
         [0030]     The design of the fuse linked relay  30  of the present invention allows a small package that is smaller than standard micro-relay packages, while carrying up to 40 amps or more. The fuse linked relay  30  according to the present invention also eliminates connections in a fuse box of, for example, a vehicle, which thereby reduces the heat and temperature rise in the fuse box. As such, a vehicle fuse box can be reduced by up to 70% in comparison with a conventional vehicle fuse box. Furthermore, the relay according to the present invention can be rated for Pulse Width Modulation, which further reduces the temperature rise in a fuse box.  
         [0031]     Furthermore, the fuse linked relay  30  of the present invention, although being described with an electromagnetic coil  34 , can utilize, for example, a pneumatic or hydraulic system in order to move the movable element  50  towards the contact terminal  54 .  
         [0032]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.