Patent Publication Number: US-6712641-B2

Title: Resilient contact and assembly thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an electrical terminal that includes a hollow conductive terminal body containing an opening for receiving a conductor, a spring being provided within a chamber defined within the terminal body for biasing the conductor toward electrical engagement with a given wall of the chamber. The spring includes a leg having an operating tab portion that extends externally of the terminal via a slot contained in said given wall, thereby to permit the spring leg to be displaced to a retracted position for the insertion or withdrawal of the conductor from the terminal chamber. 
     2. Brief Description of the Prior Art 
     Resilient electrical terminals are well known in the patented prior art, as illustrated, for example, by the prior German patent No. DE 19614977, and the U.S. patents to Wielsch, et al., U.S. Pat. No. 6,270,383 and Despang U.S. Pat. No. 6,350,162, among others. In such terminals, it is known to provide a resilient member that biases a bare conductor into engagement with the conductive terminal wall. In the German patent, a projecting portion of the spring affords means for displacing the legs of the spring toward an open condition for the insertion and removal of the conductor relative to the terminal. 
     The present invention was developed to provide a spring terminal that can be made at reasonable cost with a particularly simple design that can be connected and disconnected in a simpler manner than the various types of currently available typical spring terminals. 
     SUMMARY OF THE INVENTION 
     Accordingly, a primary object of the present invention is to provide a resilient electrical terminal including a hollow conductive terminal body containing an opening communicating with a chamber within the terminal body, and a U-shaped spring mounted in said chamber, said spring having an outwardly biased contact leg for biasing an electrical conductor that is introduced into the chamber via said opening toward electrical engagement with a given wall of the chamber, said contact leg having an operating tab that extends outwardly from the terminal body via a slot contained in the chamber wall. The terminal body and the spring are each formed by bending a strip of metal stock material. Upon operation of the operating tab, the contact leg is displaced from a normal clamping position toward a released position, thereby to permit the conductor to be inserted into, or withdrawn from, the chamber. 
     Since the resilient terminal assembly requires only a few simple parts each formed from sheet metal, it is easily and inexpensively produced. By simple manipulation of the operating tab externally or the terminal, the spring contact leg may be displaced to the released position for insertion and withdrawal of the conductor from the terminal chamber. Furthermore, a rigid conductor may be merely inserted directly into the terminal chamber by force fit and without any operation of the operating tab. 
     According to a further object of the invention, a protective synthetic plastic insulating housing may be mounted upon the terminal assembly following its soldering connection with the printed circuit board. Locking foot means may be provided for releasably connecting the protective housing with the terminal assembly and/or the printed circuit board. 
     According to another embodiment of the invention, two or more springs may be provided within a single terminal body for connecting a plurality of conductors with the terminal body. Each spring includes a leg having an operating tab portion that extends outwardly via an associated slot, respectively. Thus, selective operation of the operating lugs permits insertion and removal of the various conductors, respectively. 
     According to a further modification, the two legs of a single U-shaped spring may be utilized to bias a pair of conductors toward engagement with opposed walls of the terminal chamber, respectively, each spring leg being provided with an operating tab portion. 
     Another object of the invention is to provide a terminal block that contains one or more of the terminal assemblies, said terminal block containing first openings that receive the operating tool that engages the operating tab on a spring leg, and second openings through which the conductors are inserted within and removed from the terminal chambers, respectively. 
     The present invention permits the terminal block assemblies to be soldered to a printed circuit board, and to be subsequently enclosed in a protective housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawings, in which: 
     FIGS. 1 a - 1   c  are end elevation, top plan, and side elevation views illustrating as assembly of a plurality of resilient terminals of the present invention mounted on a common printed circuit board; 
     FIG. 2 is a sectional view of the terminal of the present invention taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is an enlarged view of the terminal assembly of FIG. 1 c;    
     FIG. 4 is a perspective view of a multi-contact terminal with certain parts disassembled for explanatory purposes; 
     FIG. 5 is a rear perspective view of the multi-contact assembly of FIG. 4; 
     FIG. 6 is a bottom perspective view of the assembly of FIG. 4; 
     FIG. 7 illustrates the manner of mounting an electrical terminal of the present invention within a terminal block that is adapted for mounting on a support rail; 
     FIG. 8 is a modification of the invention provided with a bus bar; 
     FIG. 9 is a modification of the invention where the spring member is operable to bias two conductors inserted within a single terminal; 
     FIG. 10 is a front perspective view of a terminal assembly that is mounted within an insulating housing; and 
     FIGS. 11 and 12 are top perspective and bottom perspective views respectively of the assembly of FIG.  10 . 
    
    
     DETAILED DESCRIPTION 
     Referring first more particularly to FIGS. 1-3, the resilient terminal assembly  1  of the present invention includes a hollow terminal body  5  that is formed by bending from a single sheet of a conductive metal, such as copper. The terminal  5  has a rectangular cross sectional configuration and is provided at its upper end with an opening  9  for receiving the bare end of an insulated conductor  3 , and an open bottom end  11 . Mounted within the chamber defined within the terminal body  5  is a resilient U-shaped spring  7  having a pair of leg portions  7   a  and  7   b  that are joined by a connecting portion  7   c . As best shown in FIG. 2, the first leg  7   a  is a support leg that engages the inner chamber wall  5   a  of the terminal body  5 , and the other leg  7   b  is a contact leg that is resiliently biased outwardly to displace the conductor  4  into electrical engagement with the opposed wall  5   b  of the terminal chamber. In order to retain the spring  7  within the terminal chamber, the terminal body is provided with an integral bent first horizontal support lug  17  that extends beneath the spring connecting portion  7   c , and an horizontal upper bent lug  19  that extends above the spring connecting portion  7   c . The terminal body is provided at its lower end with a pair of soldering lugs  13  that extend downwardly through corresponding openings within a printed circuit board  15 . The soldering lugs  13  may be soldered to printed circuits  15   a  that are provided on the adjacent lower surface of the printed circuit board  15 . 
     In accordance with a characterizing feature of the present invention, the second spring leg portion  7   b  that biases the conductor  3  against the terminal body wall  5   b  includes an orthogonally bent operating tab portion  7   d . This tab portion extends outwardly from the terminal via slots  21  provided in the second terminal wall  5   b , as best shown in FIGS. 2 and 3. 
     The spring leg portion  7   b  is normally biased outwardly toward the extended position I illustrated in phantom toward the second wall  5   b  of the terminal. When the operating tab portion  7   d  is displaced downwardly, the leg portion  7   b  is displaced toward the support leg  7   a , thereby to permit the conductor  3  to be inserted within or withdrawn from the terminal chamber via the opening  9  contained in the upper end of the terminal. As shown in FIG. 2, when the conductor  3  is inserted into the terminal chamber, upon release of the operating tab portion  7   d , the leg portion  7   b  is resiliently displaced outwardly to the position II to bias the conductor  3  into electricacl engagement with the conductive wall  5   b  of the terminal. 
     The operating tab portion  7   d  is integral with and extends orthogonally from the spring leg  7   b . The spring  7  is formed by bending from a single metal strip formed from a suitable resilient material, such as spring steel. The operating tab portion  7   d  extends outwardly of the terminal via the slot  21  contained in the terminal wall  5   b , as shown in FIGS. 1 c  and  3 . 
     Referring now to the modification shown in FIGS. 4-6, a pair of U-shaped springs  7  and  8  are provided in the terminal body  5 ′, said springs having first and second leg portions  7   a ,  7   b  and  8   a ,  8   b  that are connected by connecting portions  7   a ,  8   c , respectively. Operating tab portions  7   d ,  8   d  extend orthogonally from the second leg portions  7   b ,  8   b , respectively, outwardly of the terminal body via a pair of slots  21  contained in the terminal second wall  5   b ′. In this embodiment, a bottom bent portion  24  extends from the first terminal wall horizontally across the bottom opening  11  of the terminal body, thereby to serve as a stop limiting the downward travel of a pair of conductors inserted within the terminal chamber via the top opening  9  of the terminal. A pair of inwardly bent horizontal tabs  17   a ,  17   b  extend from the upper end of the terminal side walls beneath the connecting portion  7   c ,  8   c  of the springs  7  and  8 , respectively. The bottom stop portion  24  of the terminals may be provided with slots or openings  24   b  that permit the insertion of a vertical bus bar S between the spring and the first terminal wall  5   a , as will be shown in FIG.  8 . 
     While two springs  7  and  8  have been illustrated as being mounted within the terminal body, it is apparent that a greater number of springs may be provided for use with a greater number of conductors, if desired. 
     Referring now to FIG. 7, the terminal assembly  5  of the present invention may be mounted within a terminal block R having an insulating housing that is adapted for connection with a generally U-shaped supporting rail T, as is known in the art. The terminal block includes a lower tier A that contains a resilient connector C of the prior art, and a second tier B that contains the terminal arrangement  5 ′ of FIGS. 4-6. Thus, the terminal assembly  5 ′ contains a pair of springs  7  and  8  only one of which (i.e., spring  8 ) is shown in FIG.  7 . The terminal block R contains a pair of first operating openings for receiving a tool (such as a screwdriver) that engages the operating tabs  7   d  or  8   d  to manually displace the associated spring leg to the retracted position, and a pair of conductor openings  23   a ,  23   b  for the insertion and removal of a pair of conductors relative to the terminal chamber, whereby upon removal of the tool from the opening  25   a  or  25   b , the associated spring leg returns toward its extended position to bias the conductor into electrical contact with the terminal wall. 
     Referring now to FIG. 8, in accordance with the present invention, it is possible to introduce a bus bar S between the first spring leg  7   a  and the first wall  5   a  of the terminal body  5 . Thus, in this embodiment, the spring leg  7   b  biases the conductor  3  against the terminal wall  5   b , and the spring leg  7   a  biases the bus bar S into electrical engagement with the terminal wall  5   a . Stop projections  26  are bent to horizontal positions at the bottom of the terminal body. 
     Referring now to FIG. 9, the spring  70  has a pair of legs  70   a  and  70   b  that are connected by the upper connecting portion  70   c . The legs are provided with orthogonally-extending operating tab portions  70   d  and  70   d ′ that extend outwardly of the terminal body via the side walls slots  21 . Consequently, a single spring may be used to connect a pair of conductors  3  to the terminal body  5 . 
     Referring to FIGS. 10-12, the terminal block assembly of FIG. 3 may be provided with an outer insulating housing  27 , that is formed of a suitable synthetic plastic insulating material. The outer housing  27  contains tool openings  37  for inserting tools such as a screwdriver to engage the operating tab  7   d  of the various terminal assemblies, as well as second openings  35  which permit conductors to be inserted within or withdrawn from the chambers contained within the various terminals  5 . The operating tab  7   d  extend outwardly via slots  33  contained in the outer housing  27 . Locking mean such as catch hooks  39  may be provided which snap under the edge  41  of the terminal block assembly, thereby to fasten the insulating housing to the terminal block assembly. Soldering lugs  13  may be provided for soldering the assembly to the printed circuit board  15 , in the manner illustrated in FIG. 2, for example. 
     While in accordance with the provisions of the Patent Statutes the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that various changes may be made without deviating from the inventive concepts set forth above.