Patent Publication Number: US-5295873-A

Title: Double leaf spring contact with stop device

Description:
The invention concerns a double leaf spring contact with a stop device. 
     With double leaf spring contacts currently available on the market, the stop device consists of a latch that is attached to the outer edge of each fork spring arm of a fork spring arm pair and bent in a right angle toward the other fork spring arm pair within a distance from the outer edge, and a web that opposes the corresponding latch and is attached to the outer edge of each fork spring arm of the other fork spring arm pair, in which the web adjoins the free end edge of the angled area of the latch. The outer side of the spacer or stop device is arranged flush with the frontal wall of the spring arm base of the double leaf spring contact. 
     The double leaf spring contact is inserted into a cuboid-shaped chamber of a plug housing. In this particular instance, the spacer device can hinder the insertion process because the outwardly protruding elements of the spacer device adjoin the frontal edges of the chamber walls in the area of the plug opening of the chamber. Even if the contact area of the double leaf spring contact has been inserted, through tilting of the double leaf spring contact the relatively sharp-edged elements of the spacer device can strike the chamber walls and thus cause increased friction, so that a relatively high coupling force must be applied in order to insert the double leaf spring contact into a housing chamber of a plug housing. 
     The object of the invention is to create a double leaf spring contact with spacer device, in which the elements of the spacer device do not hinder the insertion of the double leaf spring contact into a housing chamber of a plug housing and thus guarantee a relatively low coupling force. 
     One example of the invention is described in the following with the aid of drawings. They show: 
    
    
     FIG. 1 a longitudinal section through a double leaf spring contact, the frontal walls and the prong base, and through a part of the plug housing chamber; 
     FIG. 2 a top view of a double leaf spring contact that was inserted into a schematic plug housing chamber (partially sectioned), in which one frontal side wall of the external enclosure spring has been omitted; 
     FIG. 3 a top view of the seam of a skid of an external enclosure spring. 
    
    
     The double leaf spring contact (1) with external enclosure spring (10) illustrated in FIGS. 1 and 2 is electrical and consists of a punched sheet metal element. The double leaf spring contact (1) consists of one generally U-shaped spring arm base (4) with two lateral side walls (6) and one frontal side wall (7). A prong element with prongs (8) that serves as stop for an electrically conducting wire (not shown) is arranged on one side of the spring arm base (4). Fork spring arms that converge in the shape of a curve are attached to the front edges of the lateral side walls (6) on the other side of the spring arm base (4), in which the fork leaf arms form a contact area for a contact stud of a counter contact (not shown), in the culmination area of the curves. Stop devices (2) that maintain a certain distance between the converging fork leaf arms (3) are arranged in the contact area. The stop devices (2) consist of web or latch-shaped elements. 
     The external enclosure spring (10) generally consists of a box-shaped spring arm base (13) and several enclosure spring fork arms (16) that connect to the lateral side walls (15). The spring arm base (13) of the external enclosure spring (10) has two lateral side walls (15) and two frontal side walls (14), in which the spring arm base (13) surrounds the spring arm base (4) of the double leaf spring contact (1) from all sides. The desired tight contact of the spring arm base (13) of the external enclosure spring (10) with the spring arm base (4) of the double leaf spring contact (1) is obtained by holding devices in form of latches (17). Two latches (17) each are constructed into the frontal side walls (14) of the external enclosure spring (10), in which the latches are bent towards the inside by approximately 180 degrees so that the spring arm base (13) is solidly connected with the spring arm base (4). 
     According to the invention, in order to ensure that the insertion of the double leaf spring contact (1) into a chamber of a plug housing (30) is not hindered by the elements of the stop device (2) that serves as spacer and to necessitate only a relatively low coupling force, skids (11) are provided on the frontal side walls (14) of the spring arm base (13) of the external enclosure spring (10) which cover the stop devices (2) from the outside. 
     One catch spring stud (18) each is punched into the lateral side walls (15) of the spring arm base (13), and these catch spring studs serve as clamping fixtures for the double leaf spring contact (1) in a chamber of plug housing (30) by the fact that they are slightly bent towards the outside, as is illustrated in FIG. 2. The skids (11) connect to the frontal side walls (14) of the spring arm base (13) in direction of the plug housing (30), with one skid (11) each provided per frontal side wall (14). Enclosure spring fork arms (16) connect to the lateral side walls (15), namely two enclosure spring fork arms (16), per lateral side wall (15). The spring arm base (13), as well as the skids (11) and the enclosure spring fork arm (16) are constructed as one piece. 
     According to the invention, the objective of the skids (11) is to cover the stop devices (2) of the double leaf spring contact (1) in order to prevent entanglement in the chamber of the plug housing (30). This objective is obtained by the fact that the skids (11) extend linearly upward and plane to the spring arm base (13) and tightly adjoin the stop devices (2). In order to obtain an improved insertion of the double leaf spring contact (1), the end areas of the enclosure spring fork arms (11) are bent towards the inside. The bent areas result in slants (12) and thus form a conical taper of the free end of the external enclosure spring (10). This conical taper ensures the simple insertion of the double leaf spring contact (1) into the corresponding chamber of a plug chamber housing (30). 
     The enclosure spring fork arms (16) are also constructed in a linear manner, but they extend transverse towards the inside in order to adjoin the free ends of the fork spring arms (3). The transverse extension of the enclosure spring fork arms (16) is obtained by the fact that the enclosure spring fork arms (16) are bent in their connecting area to their spring arm base (13). The thus formed angled area (1) can be seen in FIG. 2. 
     The enclosure spring fork arms (16) are constructed shorter than the skids (11). The termination or the end (20) of the enclosure spring fork arms (16) is located at approximately the same height as the transition of the skids (ii) from their linear to their slanted extension (12). The enclosure spring fork arms (16) that adjoin the fork spring arms (3) of the double leaf spring contact (1) from the outside ensure that the free ends of the fork spring arms (3) cannot gouge into the chamber of the plug housing (30). On the other hand, they increase the necessary tension between the fork spring arms (3) for the reception of a counter contact stud (not shown) because they adjoin the enclosure spring fork arms (16) so tightly. 
     FIG. 3 shows a top view of a skid (11), in which the spring arm base (13) of the external enclosure spring (10) connecting to the lower end of the skid (11) was omitted. The skid (11) illustrated in the drawing shows a central and continuous butt seam (21) that extends in the longitudinal direction of the skid (11) and, in a corresponding manner, also through the frontal side wall (14) (not shown) of the spring arm base (13). The butt seam (21) is a result of the manufacturing process because the external enclosure spring (10) together with the skids (11) and the enclosure spring fork arms (16) are