Abstract:
A circuit breaker for protecting electrical circuits, particularly in motor vehicles, includes a flat housing, which comprises an insulating material and has two adjacent flat plugs. A bimetal that is embodied as a snap-action element and is fixed to a flat plug serves in contacting the flat plugs together, with the contact end of the bimetal being located in an overlapping position with the counter-contact. During a contact opening as stipulated by an overcurrent, a contact separator automatically travels into the space between the opened contacts, and can be returned from its contact-separating position by the external exertion of a force acting counter to the spring pressure. A manual release device, which diverts the contact end of the bimetal from its contacting position into its contact-opening position, protrudes from the breaker housing.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a circuit breaker for protecting electrical circuits in road vehicles, having a flat, substantially parallelepiped housing, which comprises an insulating material, for a space-saving juxtaposed arrangement. The housing has two substantially parallel top surfaces, in which flat plugs for contacting with a flat-fuse holder protrude out of a housing side wall of the housing. The plugs have flat planes oriented parallel to the two top housing surfaces. The housing side wall penetrated by the flat plugs is formed by a base part that supports the flat plugs, whereas other housing walls of the housing are components of a housing cover that is pushed onto the base part, and enclose functional parts of the breaker. The flat plugs have housing-side ends adjacent to one another that protrude into the housing interior and makes a contact to one another via a bimetal snap disk that is fixed to one of the flat plugs and opens the contact in the event of an overcurrent. The housing cover has a housing opening, which is located in a housing side wall opposite the base part in the assembled state, for a manual release device that lifts the bimetal snap disk out of a position making the contact. The house opening surrounds a bearing shaft for the manual release device, the shaft extending transversely to a passage direction of the manual release device and parallel to the plane of extension of the bimetal snap disk, and being integrally formed onto the housing cover. The manual release device is snapped externally onto the bearing shaft such that, in the snapped-on position, the manual release device acts as a two-armed lever, extending beneath the bimetal snap disk with a release arm that protrudes into the housing interior for selectively acting upon the disk in a contact-opening direction, and protrudes with an actuating arm beyond the housing side wall opposite the base part. These circuit breakers are intended to be used worldwide in motor vehicles equipped with flat fuse sockets, in place of the conventional cut-out fuses according to DIN 72581-3. 
     It is the object of the invention to permit a simpler method than methods disclosed in DE-A-1099624 for breaking the circuit protected by the automatic circuit breaker arbitrarily, without an overcurrent release, in a circuit breaker of the type mentioned at the outset. For simple, manual circuit breaking, especially in the intended purpose of protecting the electrical circuits of motor vehicles, it is necessary to effectively prevent battery drainage due to creeping currents, e.g., if the vehicle is not used for an extended period of time. This is often the case, for example, from the time of the final inspection of the vehicle until it is delivered to the buyer. In the interim, the vehicle is often transported or stored over long periods. 
     The manual release device can be designated as a two-armed pivot lever whose release arm is in the inoperative position on the contact side of the bimetal snap disk. In the contact position of the bimetal snap disk, the release arm does not touch the bimetal. Rather, it is held, contactless, in this initial and inoperative position by a spring pressure that is exerted by the bearing shaft of the manual release device onto the lower leg of the release device, as a pivot drive. The special structural feature is that the manual release device acting as a two-armed pivot lever is snapped to the bearing shaft, which is embodied in one piece with the housing cover, by a movable snap connection. This construction is adapted to narrow space conditions, is simple in terms of assembly, and can be realized at a low cost. Finally, a circuit breaker in accordance with the invention can-be mass-produced. The manual release device is lightweight and operates reliably, even under the notoriously narrow conditions of numerous circuit breakers arranged in adjacent rows. When the circuit breaker according to an embodiment of the present invention includes an additional contact separator, it is unequivocally apparent whether a release motion of the release device has effected the desire contact separation: the pressing end of the contact separator protrudes from the breaker housing after the separator is manually released. The actuating arm of the manual release device that protrudes from the housing prevents the contact separator from returning due to pressure exerted on its pressing end, as well as the automatic snap contacting or reclosure of the circuit breaker that may occur afterward, when the bimetal has cooled. Therefore, the subject of the invention can easily be implemented, even in an otherwise unchanged construction of the prior art cited at the outset. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     An embodiment of the invention is explained in conjunction with the figures. Shown are in: 
     FIG. 1 a perspective, exploded view of the individual parts of the circuit breaker; 
     FIG. 2 a longitudinal section, along the line II—II in FIG. 1, through the assembled switch, in the contact position of the bimetal; 
     FIG. 3 a representation analogous to FIG. 2, with the manual release device being pivoted out to its maximum release position and, accordingly, an opened breaker; 
     FIG. 4 the breaker in the release position in accordance with FIG. 3, with the released manual release device; 
     FIGS. 5-7 enlarged, cutout representations of the contact and manual-release regions of the breaker according to FIGS. 2-4; and 
     FIG. 8 a modified embodiment of the manual release device  29 . 
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The underlying principle of the circuit breaker is similar to those disclosed in EP 0 151 692 B1, and its improved version, DE 35 26 785 C1. The subject of present application builds on these constructions by adding the option of an external manual release device, without imposing significant structural changes on the breaker. This is an important point because, should there be any confusion with regard to the following descriptions of the figures, the contents of these documents can or should serve as references. 
     In the overcurrent circuit breaker, the base part  1 , which comprises an insulating material, is injected around the two parallel flat plugs  2 ,  3 . This secures the flat plugs  2 ,  3  to the housing. The plug ends of the flat plugs  2 ,  3  protrude from the base part  1 . Their ends  4 ,  5  protrude into the interior of the circuit-breaker housing. The flat plugs  3 ,  4  extend over their entire length as known flat-fuse inserts that act as cut-out fuses, in accordance with the guidelines of known DIN Standard 72581-3. The flat plugs  3 ,  4  extend essentially parallel to the plane of the top housing surfaces  6 ,  7  of the housing cover  8  that can be pushed in the longitudinal direction  9  onto the base part  1 . In the pushed-on or assembled position, the housing cover  8  is snapped to the base part  1 . Here, the fixing opening  10  in the top housing surface  6  snaps onto the fixing tooth  11  of the base part  1 . 
     The flat plugs  2 ,  3  have a flat-rectangle cross-sectional shape over their entire length. On the inside end  4  of the flat plug  2 , the bimetal snap disk  12  is secured, e.g., welded, by its fixing end  13  to the fixing point  14 . The movable end  15  of the bimetal snap disk  12  protrudes, as a contact end, into an overlapping position with the inside end  5  of the other flat plug  3 . On its top side, this inside end  5  supports the stationary counter-contact  16  for the movable contact  17  fixed to the underside of the movable end  15  of the bimetal snap disk  12 . 
     When the bimetal snap disk  12  is cold, the movable contact  17  fixed to its movable end  15  contacts the counter-contact  16  of the flat plug  3 . This closes the current path between the two flat plugs  2  and  3 . FIGS. 2 and 5 illustrate this closed position, in which a contact separator  18  rests against the flank of the movable contact  17  facing the base part  1 . The tensed compression spring  19  presses the separator against the flank of the movable contact  17 , in the pressing direction counter to the longitudinal direction  9 . The compression spring  19  is supported with its rear end  20  against the base  1 . Mounted to the support surface  21  of the base is a centering mandrel  22  for securing the position of the compression spring  20 , which is embodied as a helical spring, inside the breaker housing. 
     The contact separator  18  constitutes one of the legs of a structure that forms a right angle in the plan view (FIG.  1 ), and whose other leg  23 , which protrudes counter to the longitudinal direction  9 , supports the pressing end  24  of the contact separator  18 , which lies between the inside ends  4 ,  5  of the flat plugs  2 ,  3 , and is therefore oriented parallel to the inside ends  4 ,  5  of the flat plugs  2 ,  3  positioned on both sides, when the contacts  16 ,  17  are in the contacting position (FIGS. 2,  5 ) and the compression spring  19  is correspondingly compressed inside the housing cover  8 . 
     When the contacts  16 ,  17  have been separated in the contact-opening direction, the movable contact  17  is not only lifted from the counter-contact  16 , but the contact of the contact separator  18  at its flank facing the base  1  is also broken (FIGS. 3,  4 ;  6 ,  7 ). This releases the compressed spring  19 , which pushes the contact separator  18  in the direction counter to the longitudinal direction  9  and into a covering position, in which it shields the fixed contact or counter-contact  16  from the movable contact  17  connected to the bimetal  12 . In this covering position, the stop  26  protruding from the underside of the contact separator  18  impacts the flank of the counter-contact  16  facing it. This stop limits the separating movement of the contact separator  18 , and positions the contact separator  18  to shield the counter-contact  16 . The compression spring  19  continues to exert a permanent pressure on the contact separator  18 , counter to the longitudinal direction  9 . In the illustrated longitudinal displacement effected by the expanded compression spring  19 , the contact separator  18  is guided as if on a rail on the top surface of the bare, inside end  5  of the flat plug  3  extending in the housing. A guide recess  27  that acts in the manner of a track groove is provided on the underside of the contact separator  18  for this purpose (FIG.  1 ). 
     In the separated position of the two contacts  16 ,  17  (FIGS. 3,  4 ;  6 ,  7 ), the pressing end  24  of the pressing leg  23  of the contact separator  18  protrudes through the opening  28  of the housing cover  8 , thereby signaling a complete contact opening. A signal color of the pressing end  24 , which is distinguishable from the housing color, can assure or improve the external recognition of this signal. 
     To this point, the described function of the overcurrent circuit breaker has been identical to that of the prior art described at the outset, in which the contact opening  16 ,  17  is initiated by a bimetal release, that is, heating of the bimetal snap disk  12 . 
     In accordance with the invention, a manual release device is provided in addition to the bimetal snap release. For this purpose, a manual release device  29  that selectively raises the bimetal snap disk  12  from its contacting position (FIGS. 2,  5 ) is provided. This device is embodied as a two-armed lever whose actuating end protrudes out of the flat side  30  of the housing cover  8  that faces away from the flat plugs  2 ,  3 . The manual release device  29  is positioned next to the leg  23  or the pressing end  24  of the contact separator  18 , on the side facing the inside end  5  of the flat plug  3 , and extends with its longitudinal direction  9  parallel to the leg  23 . 
     For the contact opening, the manual release device  29  moves the contact end  15  of the bimetal snap disk  12  from its contact side that supports the movable contact  17  in the contact-opening direction  25 . The release arm  31  of the manual release device  29  embodied as a two-armed pivot lever effects this motion as it is pivoted upward about the bearing shaft  32  embodied in one piece with the housing cover  8 . 
     The other arm, namely the actuating arm  33  of the manual release device  29 , protrudes beyond the bearing shaft  32 . The entire length of the actuating arm  33  is located outside of the housing cover  8 . This is also basically the case for the bearing shaft  32 . It is positioned between the two holding cheeks  34 ,  35 , which simultaneously assure the longitudinal guidance or orientation of the manual release device  29 , and form an integral component of the housing cover  8  and the bearing shaft  32 . On the outside, the bearing shaft  32  is positioned in front of the housing opening  36 , through which the manual release device  29  protrudes into the housing interior. 
     The manual release device  29  is a one-piece, approximately U-shaped component that comprises an insulating material, and whose two U-legs extend around the bearing shaft  32 . The one U-leg, namely the lower one in the figures, is formed by the actuating arm  33  and the release arm  31  protruding into the housing interior. The bearing shaft  32  of the manual release device  29  is oriented approximately parallel to the bimetal snap disk  12  and the top housing surfaces  6 ,  7 . It extends perpendicular to the drawing planes of FIGS. 2 through 7. 
     The U-leg of the manual release device  29  that is positioned, as a fixing leg  37 , above the bearing shaft  32  is provided with a retaining latch  38  that extends behind the bearing shaft  32  and protrudes in the direction of the release leg  31 . 
     Furthermore, the fixing leg  37  has on its top side a protruding housing stop  39 , which limits the insertion length of the manual release device  29  vis-à-vis the housing opening  36 , and can be seen in its stopped position at the top housing surface  6  in FIGS. 2,  5 . The crosshead  40  of the U-shape forms the actuating arm  33  of the manual release device  29 . 
     The inside flank of the lower U-leg, namely the release arm  31  of the manual release device  29 , is hollowed out in approximately the central region of its longitudinal extension to form the bearing shell  41 . 
     The manual release device  29  is snapped onto the bearing shaft  32  by a movable snap connection. To this end, its two U-legs resiliently extend as integrated snap elements, and/or as counter-surfaces cooperating with the snap elements, around the bearing shaft  32 . When the manual release device  29  experiences a releasing pivoting movement  42 , the U-legs of the manual release device  29  has an elastically spreading cross-sectional shape, so the elastic spring pressure accumulated by the spreading action is effective as the restoring pressure that automatically pivots the manual release device  29  into its initial pivoting position, counter to the release pivoting  42 . This cross-sectional shape is characterized by a certain asymmetry, specifically the fact that the cross-sectional dimension of the bearing shaft  32  that acts upon the U-legs  31 ,  37  in the release pivoting position (FIGS. 3,  6 ) is larger than the cross-sectional dimension that acts upon the U-legs  31 ,  37  in the inoperative position (FIGS. 2,  4 ,  5 ,  7 ,  8 ) of the manual release device. This asymmetry also creates a counter-stop surface for the retaining latch  38  and a pivot stop  44  for the actuating arm  33  for limiting the pivoting range of the manual release device  29 . 
     The U-shape and the resilient consistency of the manual release device  29 , as well as the cross-sectional shape of the bearing shaft  32 , which deviates from a circle and more closely approximates an ellipse, are advantageous for numerous reasons. Regardless of the cross-sectional shape of the bearing shaft  32 , the manual release device  29  is simply and securely snapped onto the bearing shaft  32 . The U-leg ends of the manual release device  29  that lie in the housing opening  36  are merely pushed on from the outside and snapped in place. FIGS. 5 and 7 illustrate the pushed-on or inoperative position. Here, the release arm  31  of the manual release device  29  is located beneath the bimetal  12 . If the manual release device  29  is rotated clockwise about the bearing shaft  32 , the release end  31  is raised. It extends beneath the bimetal snap disk  12  and raises it into a position that lifts the contact  17  from the counter-contact  16 . This breaks the contact of the contact separator  18  with the movable contact  17 , and the contact separator travels into its covering position (FIGS. 3,  6 ) under the pressure of the compression spring  19 , which prevents a reclosure, that is, a return of the bimetal  12  or the movable contact  17  connected thereto into its contacting position. If the clockwise pivoting pressure P (FIGS. 3,  6 ) exerted externally onto the actuating arm  33  of the manual release device ceases, the manual release lever  29  is released, and pivots counterclockwise back into the initial position shown in FIGS. 4 and 7 due to the accumulated spreading pressure acting between the two U-legs and exerted by the bearing shaft. In this initial position, the release arm  31  maintains a clear distance from both the bimetal  12  and the inside end  5  of the flat plug  3 . 
     FIG. 8 shows a modified embodiment of the manual release device  29 . The modification concerns the arrangement of an actuating tail  46 , which protrudes beyond the head surface  45  of the crosshead  40  of the manual release device  29 . The actuating tail  46  protrudes in the direction counter to the longitudinal extension of the release arm  31 , and is positioned at the point of intersection of the longitudinal directions of the crosshead  40  and the release arm  31  or actuating arm  33 . A critical point is that the arrangement is shifted off-center relative to the bearing shaft  32 , both in the horizontal and vertical planes (FIG.  8 ), such that nearly every pressure effect exerted on the actuating tail generates a force component, independently of the direction of the pressure, that is converted into a pivoting movement of the manual release device  29  that releases the circuit breaker. The directional arrow  47  indicates the pivoting direction  47 , or the torque resulting therefrom. Directional arrows also indicate the directions of movement  48 ,  49  that lead to such a torque effect. 
     Moreover, the manual release device  29  is provided with a color that clearly contrasts with that of the housing, and is selected analogously to the safety colors in accordance with DIN 72581-3, which even facilitates a reliable selection and manual actuation in a multiple-row arrangement.