Patent Publication Number: US-6667448-B2

Title: Contact element

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 09/589,308, filed Jun. 7, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a contact element for an electrical switching apparatus. 
     2. Brief Description of the Background of the Invention Including Prior Art 
     Such contact elements are already known, wherein different constructions of actuating tappets are employed for the different switching functions ‘opening’ and ‘closing’. It is here a disadvantage to have a high number of individual parts to be fabricated and the requiring assembly as well as the expensive assembly mounting of the contact elements. 
     It is an object of the present invention to furnish a contact element of the initially described kind, which avoids the recited disadvantages. 
     It is a further object of the invention to furnish a versatile contact element with a low number or required parts. 
     It is yet another object of the invention to construct a contact switch such that it can be assembled both as a normally open switch and as a normally closed switch. 
     These and other objects and advantages of the present invention will become evident from the description which follows. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides a contact element for electrical switching apparatus having a casing with a basis part and cover part, two electrical fixed contacts having connections for electrical conductors and disposed inside of the casing, and an actuating tappet supported over a first spring means in the casing and movable in an axial direction for receiving of a contact bridge, wherein the contact bridge serves for connecting or, respectively; interrupting the electrical connection between the two fixed contacts, wherein the actuating tappet is constructed such that the contact bridge can be disposed in two different positions having a distance from each other at the actuating tappet. 
     According to a further embodiment of the contact element, the casing of the contact element and by adaptation thereto, the actuating tappet is constructed advantageously such that the actuating tappet is also mountable having an incorporated position rotated by 180 degrees around a perpendicular axis relative to a longitudinal axis of the actuating tappet. 
     The invention comprises furthermore electrical switching apparatus such as in particular manually actuable input apparatus, for example pressure switches or rotary switches, wherein the contact device is formed by a contact element according to the present invention. Furthermore the present invention also comprises power switching apparatus such as contactors, control gates, power switches, and power circuit breakers or the like, wherein then the auxiliary switch is formed by contact elements according to the present invention. 
     Further details and advantages of the invention result from the following embodiment illustrated by way of the FIGS. 
     The novel features which are considered as characteristic for the invention are set forth in the appended claims. The invention itself, however, both as to its construction and its method of operation, 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 drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the accompanying drawing, in which are shown several of the various possible embodiments of the present invention: 
     FIG. 1 is a schematic perspective view of a first embodiment of the invention contact element without cover part as an opening switch for front side mounting; 
     FIG. 2 shows an exploded view of the contact element according to FIG. 1; 
     FIG. 3 shows a perspective detailed view of the tappet arrangement of the contact element according to FIGS. 1 and 2; 
     FIG. 4 shows a perspective view of the contact element without cover part as a closing switch for the rearside mounting; 
     FIG. 5 shows an explodee view of the coltact element according to FIG. 4; 
     FIG. 6 shows a perspective view of the tappet arrangement of the contact element accordimg to FIGS.  4  and  5 . 
    
    
     DESCRIPTION OF INVENTION AND PREFERRED EMBODIMENT 
     FIG. 1 shows the contact element according to the present invention in an embodiment as a normally closed switch and as an opening switch for front side mounting. The contact element comprises a casing  2 , two fixed contacts  4  with connections for external electrical conductors and a tappet arrangement  6 . 
     The casing  2  is furnished with clamping elements disposed substantially parallel to a direction of motion of the electrical tappet arrangement  20 , but disposed remote from the tappet arrangement  6  on the sides of the casing  2  for positioning the contact element in an appropriate casing support. 
     Advantageously the casing  2  is constructed of two parts, that is comprising a base part  8  carrying the plunger or tappet arrangement  6  and the fixed contacts  4  and a cover part  10  as shown in FIG.  2 . 
     Each fixed contact  4  here has the shape of screw connections as shown in FIG. 2 comprising a contact plate  14  carrying a contact piece  12 , a clamping screw  16 , and a pressure plate  18  for clampingly receiving of external conductor connections. The plane of the flat contact plate  14  extends in a plane disposed substantially perpendicular to the direction of motion of the tappet arrangement  6 . Preferably a separate contact plate  14  is employed for each contact piece  12 . The contact plates  14  leave a center opening in their assembled position to allow passage of the tappet arrangement in their middle. The contact pieces  12  are disposed closely spaced to the middle opening between the two contact plates  14 . Tensioning spring clamps or other connection kinds are also employable instead of the screw connections. 
     The tappet arrangement  6  as shown in FIG. 3 comprises an actuating tappet  20 , a contact bridge  24  carrying two contact pieces  22 , a foot part  26  preferably comprising an isolating material, and spring means  28 ,  29 . The tappet arrangement  6  is constructed according to the present invention such that the contact bridge  24  can be disposed in two different positions having an axial distance from each other at the actuating tappet  20 . A first position is the position A, wherein the actuating tappet  20  is formed as an opening tappet as shown in FIGS. 1 through 3 and a second position is the position B, wherein the actuating tappet  20  is formed as a closing tappet as shown in FIGS. 4 through 6. The actuating tappet  20  is disposed in a normally closed position according to FIGS. 1 through 3 and in a normally open position as shown in FIGS. 4 through 6. The contact bridge  24  has two contacts disposed on one face of the contact bridge  24 , wherein said contact bridge is extending in a plane disposed perpendicular to the motion direction of the actuating tappet  20 . The contact pieces  22  are disposed sideways relative to the structure of the actuating tappet  20  for being capable of engaging a respective one of the contact pieces  12 . Preferably, a perpendicular arm part  32  is furnished on the actuating tappet  20 , such that the contact bridge  24  can rest against a front plane and a rear plane of the perpendicular arm part  32  as desired. The position of the contact bridge  24  relative to the perpendicular arm part  32  is always such that the contact pieces  22  face the perpendicular arm part  32 . 
     The foot part  26  electrically isolating the contact bridge  24  in the first position A against the spring means  28  is essentially formed square, or rectangular and exhibits a sack hole shaped recess on its side disposed toward the spring  28  for receiving the spring  28 . The four virtual edges of the foot part  26  extending in longitudinal direction are formed as grooves, which cooperate with inwardly directed projections of the longitudinal arm parts  30 ,  31  for purposes of guiding. The foot part  26  is constructed such that it can be mounted in all four rotated positions relative to a longitudinal axis of the actuating tappet  20 , whereby additionally a further simplification of assembly is accomplished. The foot part  26  exhibits a fixation recess on the side disposed toward the contact bridge  24 , wherein the fixation recess cooperates with a protrusion of the contact bridge  24  for purposes of fixation of the contact bridge  24 . The foot part  26  can be formed such as to match the shape of the side of the contact bridge  24  disposed remote relative to the perpendicular arm part  32 . 
     According to a preferred embodiment of the invention the actuating tappet  20  is formed as a plastic injection molding part, which exhibits a double H shape as seen in a longitudinal section and which is formed of longitudinal arm parts  30 ,  31  and out of two perpendicular arm parts  32 ,  33 , wherein the two oppositely disposed faces of the perpendicular arm part  32  define the positions A and B and form in each case a rest face for the contact bridge  24  in the respective opening position or, respectively, closing position. The perpendicular arm part  32  is disposed such between the longitudinal arm parts, that the longitudinal axis X of the tappet arrangement  6  forms a perpendicular line onto at least one of the rest and support faces of the perpendicular arm part  32 . According to another embodiment the rest face or the rest faces can also be formed inclinedly falling or inclinedly rising from one longitudinal arm part  30 ,  31  to the oppositely disposed longitudinal arm part  31 ,  30  as shown in FIG.  3 . The contact bridge  24  and the contact pieces  22  then have to be formed corresponding to the recited inclination. A self-cleaning of the contact pieces  12 ,  22  during their cooperation and co-action is accomplished thereby. 
     The contact bridge  24  can be disposed in the position A between the free ends of the longitudinal arm parts  30 ,  31  according to the embodiment of FIGS. 1 through 3 and the contact bridge  24  is supported in the assembled state at the casing  2  through the first spring means  28 . The spring means  28  serves here as a restoring spring for the tappet arrangement  6  and simultaneously as a contact pressure spring for the contact bridge  24 . 
     The contact element according to FIGS. 1 through 3 is furnished for front side assembly based on its construction. The contact element is also suitable for rearside mounting based on a different assembly of the same construction parts. For this purpose and starting with the illustrated arrangement of the construction parts, the complete tappet arrangement  6  is rotated by 180 degrees around the perpendicular axis Y relative to the longitudinal axis of the tappet, such that the spring element  28  is supported at the oppositely disposed casing wall recognizable in FIG. 4, but not illustrated in detail here. Advantageously also the basis part  8  of the casing  2  is adapted by way of construction to the actuating tappet  20 . For this purpose the basis part  8  exhibits at its oppositely disposed front faces running perpendicular to the direction of motion of the actuating tappet  20  in each case pairwise disposed openings for feeding through of the free ends of the actuating tappet  20 . The basis part  8  further includes guide elements for allowing the actuating tappet  20  to slide in the basis part  8 . The openings at the one casing front side serve for feeding through of the free ends of the actuating tappet  20  incorporated into the contact element, while the other openings disposed in the oppositely disposed casing front side serve for the feeding through of the free ends of an actuating tappet of a contact element attached in piggyback fashion, such that a simultaneous actuation of the two contact elements becomes possible. If the fixed contacts  4  should not be furnished on two sides with contact pieces  12 , then the contact pieces  12  are also to be exchanged against fixed contacts  4  with corresponding contact pieces. 
     The contact arrangement is illustrated in FIGS. 4 through 6 as a closing contact for the rearside mounting of for example a top hat rail. The contact bridge  24  is disposed on the oppositely disposed face B of the perpendicular arm part  32  in the intermediate space between the two perpendicular arm parts  32 ,  33  and is supported in the intermediate space at the other perpendicular arm part  33  through the second spring element  29  according to this embodiment. The second spring element becomes necessary for a normally open contact switch, wherein contacts are formed when pressure is applied against the restoring force of the spring means  28 . The spring means  28  serves exclusively as a restoring spring according to this embodiment and for this reason also the foot part  26  can be dispensed with. The action of the spring means  28 ,  29  is directed parallel and coaxial to the longitudinal axis of the actuating tappet  20 . The contact pressure onto the contact bridge  24  is assured by the additional spring means  29 . 
     At least one groove  34  formed on the inner side of the longitudinal arm part  30  and preferably extending perpendicular to the longitudinal axis X exists in order to simplify assembly, whereby the contact bridge  24  can be introduced into the intermediate space without having to be rotated. 
     The ends of the actuating tappet  20  are preferably formed for reliably accepting alternatively either a push button or the spring  28  through the foot part  26 . The axial length of the casing  2  in parallel to the axis of the actuating tappet  20  substantially can correspond to the total length of the actuating tappet  20 . This allows a compact construction of the contact element. 
     An electrical instruction apparatus such as a pressure switch or a rotary switch or the like can be constructed, wherein a contact element according to the present invention is connected to the instruction apparatus and is employed for switching purposes. 
     A power switching apparatus such as a power switch, a circuit breaker and the like can have a contact element according to the present invention attached, wherein a contact element allows switching on and off the power switching apparatus. 
     The present invention is not limited to the embodiments described above but comprises also all embodiments operating in the same way in the sense of the present invention. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of switching system configurations and plunger procedures differing from the types described above. 
     While the invention has been illustrated and described as embodied in the context of a contact element, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.