Abstract:
A circuit breaker includes a bimetallic snap-action disk fixed to a bimetallic connection disposed in the vicinity of a fixed contact connection inside a coverable housing. The bimetallic disk has a contact end with a contact superposed with a fixed contact of the fixed contact connection in such a way that a contact is established. When the contacts are opened, a spring-loaded isolating slide moves between the contacts. The isolating slide has an illuminated push button for reliably identifying a disconnection.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a continuing application, under 35 U.S.C. §120, of copending International Application No. PCT/EP2004/011813, filed Oct. 19, 2004, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German Patent Application 103 48 864.2, filed Oct. 21, 2003; the prior applications are herewith incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION  
     Field of the Invention  
       [0002]     The invention relates to a circuit breaker having a bimetallic snap-action disk fixed to a bimetallic connection disposed within a housing adjacent a fixed contact connection. The bimetallic disk has a contact end with a bimetallic contact which is in a contact-making, overlapping position with a fixed contact of the fixed contact connection. In the event of the contacts opening, a spring-loaded isolating slide moves between the contacts. The isolating slide has an illuminated pushbutton.  
         [0003]     Such a circuit breaker, which is known from German Utility Model DE 298 24 696 U1, corresponding to U.S. Pat. No. 6,590,489, has a bimetallic snap-action disk, which is fixed to a bimetallic connection. The bimetallic connection is disposed within a housing base adjacent a fixed contact connection. The housing base can be covered through the use of a cap that is made, for example, of plastic or metal. The bimetallic snap-action disk carries a bimetallic contact which, within the housing, is in a contact-making, overlapping position with a fixed contact of the fixed contact connection.  
         [0004]     In the event, for example, of an overcurrent causing the contacts to open due to the bimetallic snap-action disk being snapped up or bent up, an isolating slide, which is spring-loaded through the use of a spring element, moves between the contacts. As a result, the bimetallic snap-action disk is prevented from snapping back into the contact-making, closed position even once the bimetallic snap-action disk has cooled down. In that case, a circuit, into which the circuit breaker has been inserted as a fuse element, remains interrupted.  
         [0005]     Such a circuit breaker is used in particular as a fuse element in circuits in a motor vehicle and, for that purpose, is inserted into corresponding flat fuse bases of the motor vehicle. Further application areas for such circuit breakers having a bimetallic snap-action disk are possible in domestic electrical appliances or the like.  
         [0006]     In a prior art circuit breaker disclosed in U.S. Pat. No. 4,573,031, an isolating slide is connected in one piece with a pushbutton protruding from a housing. The isolating slide which is moved between the contacts in the event of tripping, can be manually brought into its starting position through the use of the pushbutton.  
         [0007]     In a prior art circuit breaker disclosed in U.S. Patent Application Publication No. US 2002/0149464, an additional luminous element for optically indicating a tripping event is disposed within a pushbutton housing and protrudes therefrom. In accordance with U.S. Pat. No. 4,630,020, such a luminous element can also be entirely disposed within a pushbutton that is constructed in a hollow manner or spaced apart from the isolating slide within the housing in the region of an opening of the housing provided with a transparent covering.  
       SUMMARY OF THE INVENTION  
       [0008]     It is accordingly an object of the invention to provide a circuit breaker having a bimetallic snap-action disk, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which has been improved in terms of its tripping identification.  
         [0009]     With the foregoing and other objects in view there is provided, in accordance with the invention, a circuit breaker. The circuit breaker comprises a housing, a fixed contact connection being disposed in the housing and having a fixed contact, and a bimetallic connection disposed in the housing adjacent the fixed contact connection. A bimetallic snap-action disk is fixed to the bimetallic connection and has a contact end with a bimetallic contact in a contact-making, overlapping position with the fixed contact of the fixed contact connection. A spring-loaded isolating slide moves between the fixed contact and the bimetallic contact upon the fixed contact and the bimetallic contact opening. The isolating slide has an illuminated pushbutton formed of a transparent material and has a material cutout formed therein. An electrical luminous element for illuminating the pushbutton is fixed in position inside the housing in the vicinity of the material cutout.  
         [0010]     As a result of the illuminated pushbutton being connected within the housing to the isolating element, on one hand tripping of the circuit breaker is displayed visually in the form of a light signal that is visible from the outside. In addition, on the other hand, as a result of the coupling between the illuminated pushbutton and the isolating element, which is displaced between the contacts in the event of tripping, it is also possible for the pushbutton position, which protrudes further out of the switch housing, in comparison with a normal, fault-free position, by the displacement path of the isolating element, to be detected mechanically or manually from the outside. In addition, the actuation of the pushbutton is used to guide the isolating element back out of the contact isolating position, so that the contacts reach the contact position due to the spring force of the bimetallic snap-action disk.  
         [0011]     The pushbutton is mechanically coupled to the isolating element which is in the form of a slide, within the housing, i.e. within the housing base in the case of a housing base that can be covered through the use of a housing cap. A latching or snap-action connection is provided for this purpose. In this case, the pushbutton expediently has at least one and preferably two latching arms having end-side latching cams, which engage in corresponding cutouts in the isolating element for the purpose of producing the latching or snap-action connection. It is also possible for the latching cams to be provided on the isolating element and for the latching cutouts to be provided on the pushbutton.  
         [0012]     In order to illuminate the pushbutton, an electrical luminous element, for example a lamp or a light-emitting diode, is provided. The luminous element is disposed in such a way that it is fixed in position in the housing or housing base. In this case, the luminous element can be connected within the housing between the bimetallic connection and the fixed contact connection. With this wiring embodiment, the luminous element has current flowing through it when the bimetallic snap-action disk has been tripped, so that in the OFF state, i.e. when the circuit breaker has been tripped, the pushbutton is illuminated.  
         [0013]     In accordance with an alternative wiring embodiment, contact is made between a first connection of the luminous element and the bimetallic connection within the housing, while a second connection of the luminous element is passed out of the housing base. In this embodiment, in which the luminous element connection which is passed to the outside is connected, for example, to a neutral conductor of a power supply system, in the normal state, i.e. in the contact-making, overlapping position of the contacts and with corresponding external wiring of the circuit breaker, the luminous element has current flowing through it, so that the pushbutton illuminates in the ON state and fails to be illuminated in the event of the contacts opening (OFF state).  
         [0014]     The luminous element is disposed within the housing or housing base in the region of a material cutout in the pushbutton. Due to this material cutout, a pushbutton shaft and a pushbutton section, which protrudes beyond the pushbutton shaft and always at least partially protrudes beyond the luminous element even when the contacts are opened, is formed along the pushbutton. In this case, the shaft length is matched to the displacement path of the isolating element which is coupled to the pushbutton, with the result that the pushbutton, with its pushbutton shaft, can move or can be displaced in a contactless manner along the stationary luminous element. In this case, a gap formed between the pushbutton section and the luminous element is increased in the event of tripping by the displacement path of the isolating element or the pushbutton coupled to the isolating element.  
         [0015]     The pushbutton and the isolating element, which moves between the contacts in the event of tripping, form a two-part isolating slide in the latched coupling state, in which case different materials are expediently used for the two parts of this isolating slide. The isolating element which, in the installed state, bears against the bimetallic contact and/or against the fixed contact, is thus on one hand made from a very thermally resistant plastic, i.e. a plastic which is resistant to thermal deformation, and expediently from a thermosetting plastic. On the other hand, the pushbutton is made from a transparent material, preferably from a transparent plastic. This ensures that the light emitted from the luminous element passes to the outside through the pushbutton shaft and/or the pushbutton section, which protrudes beyond the pushbutton shaft of the pushbutton.  
         [0016]     In order to achieve a degree of prefabrication which is as high as possible and using as few individual parts as possible, the fixed contact connection and the bimetallic connection are in the form of identical flat contacts. In their central region, these contacts are bent out in the manner of a trough. The trough thus formed is then either used for fixing the bimetallic snap-action disk or for accommodating the fixed contact. For this purpose, the two identical flat contacts are inserted into the housing base, rotated through 180° with respect to one another, in relation to their longitudinal axis, and are fixed there expediently through the use of connecting rivets. When using tubular or hollow rivets, they take on the further function of receiving the connections or the individual connection of the luminous element in a contact-making manner.  
         [0017]     The advantages achieved by the invention reside in particular in the fact that illumination which is integrated in a pushbutton of an isolating slide, that can be actuated from the outside by the pushbutton, of a circuit breaker having a bimetallic snap-action disk, makes it possible to achieve reliable tripping identification in a simple manner. The pushbutton thus takes on a dual function which is, on one hand, for guiding the isolating element back out of the contact isolating position when the pushbutton is actuated and, on the other hand, for optical signaling of an instance of the circuit breaker tripping as a result, for example, of an overcurrent.  
         [0018]     Other features which are considered as characteristic for the invention are set forth in the claims which are appended below.  
         [0019]     Although the invention is illustrated and described herein as embodied in a circuit breaker having a bimetallic snap-action disk, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
         [0020]     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIGS. 1 and 2  are diagrammatic, perspective views of a circuit breaker having a bimetallic snap-action disk and illuminated pushbutton, in which a housing base is covered  FIG. 1  and uncovered in  FIG. 2 ;  
         [0022]      FIG. 3  is an exploded, perspective view of the circuit breaker shown in  FIG. 1 , with an isolating slide decoupled in the pushbutton and an isolating element;  
         [0023]      FIGS. 4 and 5  are respective enlarged, side-elevational and front-elevational views of the isolating slide; and  
         [0024]      FIGS. 6 and 7  are schematic diagrams of two different circuit embodiments of a luminous element inserted into a housing base. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     Referring now in detail to the figures of the drawings, in which mutually corresponding parts are provided with the same reference numerals, and first, particularly, to FIGS.  1  to  3  thereof, there is seen a circuit breaker  1  that includes a housing base  3 , which can be covered by a housing cap  2  and in which a bimetallic connection  4  and a fixed contact connection  5  are disposed parallel and adjacent one another. The connections  4  and  5 , which are passed out of the housing base  3  on a connection side with respective connections ends  4   a  and  5   a  thereof, are fixed within the housing base  3  through the use of hollow rivets  6 .  
         [0026]     As can be seen in  FIG. 3 , the connections  4  and  5  are in the form of identical flat contacts and are bent back so as to form a trough  4   b ,  5   b . The connections  4   b ,  5   b  are provided with openings  7  in respective trough apexes. In an installed state, the opening  7  in the bimetallic connection  4  is used for fixing a bimetallic snap-action disk  8  through the use of a rivet  9 , and the opening  7  in the fixed contact connection  5  is used for accommodating a fixed contact  10 . The bimetallic snap-action disk  8  carries a bimetallic contact  12  at a contact end  11  thereof facing away from the bimetallic connection  4 . In the installed state, this bimetallic contact  12  is in a contact-making, overlapping position with the fixed contact  10 , as is seen in  FIG. 2 .  
         [0027]     A two-part isolating slide  13 , which is expediently made from plastic, is disposed between the bimetallic connection  4  and the fixed contact connection  5  within the housing base  3 . The two-part isolating slide  13  includes an L-shaped isolating element  14  and a pushbutton  15 , which is mechanically coupled to the isolating element  14 . A latching or snap-action connection provided for this purpose is formed by two latching arms  16  which, in the exemplary embodiment, are provided on the pushbutton  15  and carry mutually facing cams  16   a  on a free-end side. The pushbutton  15  is snapped onto the isolating element  14  through the use of the latching arms  16 , in which case the latching cams  16   a  engage in corresponding latching cutouts  17  in the isolating element  14 . This can be seen relatively clearly in  FIG. 5 .  
         [0028]     As is shown in the side view of the isolating slide  13  in  FIG. 4 , the pushbutton  15  has a material cutout  18  so as to form a pushbutton shaft  15   a  and a pushbutton section  15   b  which protrudes beyond the pushbutton shaft  15   a . In the final mounted state, a luminous element  19 , for example a lamp or a light-emitting diode, is positioned in the material cutout  18 . The pushbutton  15  is made from a transparent material, preferably from a transparent plastic.  
         [0029]     The luminous element  19  is at least partially overlapped by the pushbutton section  15   b  of the pushbutton  15  in each displacement position, extending in the direction of an arrow  20  in  FIG. 4 , of the isolating slide  13 . Therefore, in any position of the isolating slide  13 , the light emitted by the luminous element  19  passes to the outside, i.e. to outside the switch housing  2 ,  3 , through the pushbutton shaft  15   a  and/or the pushbutton section  15   b  of the pushbutton  15 .  
         [0030]     The isolating slide  13  has the function of moving between the fixed contact  10  and the contact end  11  in the event of the circuit breaker  1  having been tripped, for example, due to an overcurrent. As a result, the contact end  11  with the bimetallic contact  12  moves away from the fixed contact  10  due to the bimetallic snap-action disk  8  opening or bending up. For this purpose, the isolating slide  13  is spring-loaded with a spring element  21 . In this case, one side of the spring element  21  is supported on an underside  22  of the isolating element  14 . The underside  22  is remote from the pushbutton  15 . The other side of the spring element  21  is supported on the housing base  3 . The electrically insulating isolating function is taken over by an isolating limb  14   a  of the isolating element  14 . The isolating limb  14   a  extends transversely with respect to the shaft extent of the pushbutton  15  and merges at right angles with a shaft  14   b  of the isolating element  14  which has the latching cutouts  17 .  
         [0031]     The isolating element  14  itself is made from a temperature-resistant plastic material or a plastic material which is resistant to thermal deformation, preferably from a thermosetting plastic. The reason for this is the fact that the isolating element  14  is always at least approximately in touching contact with the contacts  10 ,  12  which carry current during operation.  
         [0032]     In the tripping-free ON state of the circuit breaker  1  illustrated in  FIG. 2 , the isolating limb  14   a  of the isolating element  14  bears against the contacts  10 ,  12  on the underside, remote from the pushbutton  15 , of the contacts  10 ,  12 . In the event of tripping, in the case of which the bimetallic contact  12  is lifted off of the fixed contact  10  as a result of the bimetallic snap-action disk  8  bending up or snapping up, the isolating slide  13  is displaced in the displacement direction  20  as a result of the spring force brought about by the spring element  21  and is guided precisely between the two contacts  10 ,  12  while forming an abutment or stop within the housing base  3 . As a result, the two contacts  10 ,  12  are mechanically spaced apart from one another and electrically insulated from one another.  
         [0033]     As a result of this pushing movement of the isolating slide  13 , the pushbutton  15  is displaced by the same displacement path in the displacement direction  20  due to the fact that it is coupled with the isolating element  14 , and in the process is guided over the housing cap  2  towards the outside of the switch housing  2 ,  3  through this displacement path. In this final tripping position of the isolating slide  13 , the pushbutton  15  protrudes beyond a dome-like pushbutton sleeve  23  placed onto the housing cap  2 . This pushbutton sleeve  23  may be an integral component or part of the housing cap  2  or may be snapped onto it as a separate part.  
         [0034]     In the event of tripping, isolation of the contacts  10 ,  12 , due to the isolating slide  13  being pushed between them, is maintained until the isolating element  14  is displaced in the opposite direction along the displacement direction  20  due to the pushbutton  15  being depressed. As a result of the spring force of the bimetallic snap-action disk  8  once it has cooled down, the bimetallic contact  12  is again pressed against the fixed contact  10 . In this contact-making, overlapping position, the isolating slide  13  is held in its initial position in which it has been guided back and which corresponds to the ON state of the circuit breaker  1 .  
         [0035]     With regard to the wiring for the luminous element  19  which can be seen comparatively clearly in  FIG. 2 , a first connection  19   a  is passed out of the housing base  3  through an ohmic resistor  24  so as to form an external supply connection  25 . The supply connection  25  in this case is expediently passed outward on the same housing side of the housing base  3 , on which the connection ends  4   a ,  5   a  of the respective connections  4  and  5  also lie. A second connection  19   b  of the luminous element  19  is guided into the hollow rivet  6 , which fixes the bimetallic connection  4  within the housing base  3 , and makes electrical contact with the bimetallic connection  4  through the hollow rivet  6 , for example by making plugging contact with the hollow rivet  6  or being soldered thereto.  
         [0036]     In accordance with a wiring embodiment illustrated in the form of a schematic diagram in  FIG. 6 , the luminous element connection  19   a , which is passed to the outside, is connected, for example, to a neutral conductor of a power supply system, and the luminous element  19  has current flowing through it in the normal state, i.e. in the contact-making, overlapping position of the contacts. With corresponding external wiring, the pushbutton thus illuminates in the ON state and is not illuminated in the OFF state when the contacts  10 ,  12  are open.  
         [0037]     In accordance with a further wiring embodiment shown in  FIG. 7 , the luminous element  19  can also be wired exclusively within the housing in a non-illustrated manner. For this purpose, the connection  19   a  (of the luminous element  19 ) which is passed to the outside in accordance with the embodiment shown in  FIGS. 2 and 6 , is passed in an electrically contact-making manner into the hollow rivet  6 , which fixes the fixed contact connection  5 , in an analogous manner to the plugging contact-making of the connection  19   b . In this case, the luminous element  19  can in turn be switched on by using a series circuit including the nonreactive resistor  24  and the luminous element  19  between the bimetallic connection  4  and the fixed contact connection  5 . In this wiring embodiment, the luminous element  19  has current flowing through it when the bimetallic snap-action disk  8  has been tripped, with the result that the pushbutton  15  is illuminated in the OFF state and is not illuminated in the ON state.  
         [0038]     In both wiring embodiments, but in particular with the wiring embodiment shown in  FIGS. 2 and 6 , instead of open wiring for the luminous element  19  and the resistor  24 , the resistor  24  and the soldered joint formed between the resistor  24  and the connection  19   a  can be covered by non-illustrated shrink-down tubing. As a result, undesirable electrical contact-making is reliably avoided.  
         [0039]     The circuit breaker  1  described herein having an illuminated pushbutton  15  is suitable for a large number of application areas, for example as motor, transformer or cable drum protection.