Abstract:
For transmitting high currents, such as in the electrical system of a motor vehicle for example, a contact element is proposed which is rolled and stamped from sheet-metal material and which consists of a contact-making section, a conductor-connecting section and a fastening section with an overlapping sleeve. In the contact element, the sleeve is at a radial distance from the fastening section.

Description:
The invention relates to a contact element made of stamped and rolled sheet-metal material and having a contact-making section, a conductor-connecting section, and a fastening section for fastening the contact element in a receiving chamber in an insulating body. 
     Contact elements of this kind are used in order, for example, to pass on currents from a current source to the consumer in the electrical system of a motor vehicle. 
     It is known practice, in the automotive engineering field, to use contact elements, which are produced as stamped bending contacts, for transmitting currents. However, this is only possible in the case of relatively low current intensities, since major heating-up of the contact material and, in particular, of the fastening material occurs in the case of high currents. 
     The underlying object of this invention is therefore to construct a contact element of the initially mentioned type in such a way that the transmission of high current intensities is ensured and the heating-up of the contact elements and fastening material is reduced to a minimum. 
     SUMMARY OF THE INVENTION 
     The object of this invention is achieved through the fact that there is pushed on, over the fastening section of the contact element, a sleeve which is at a radial distance from the said fastening section. 
     Advantageous refinements are indicated in claims  2  to  10 . 
     The advantages obtained with the aid of the invention consist, in particular, in the fact that, because of the radial distance of an overlapping sleeve on the fastening section of the contact element, only moderate transmission of heat to the material of the receiving chamber in the insulating body occurs. Under these circumstances, constant dissipation of heat is obtained as a result of the permanent circulation of air through the cavities in the contact elements which are stamped and shaped from sheet-metal material. 
     Further advantages of the invention lie in the fact that the plugging-in forces of the pin contact have gentle resilience during the initial plugging-in operation and a heightened spring tension is present during the rest of the plugging-in operation, the spring characteristic having a progressive development. 
     Furthermore, components produced in this way represent a cost-effective alternative to solid contact elements. 
     An exemplified embodiment is represented in the drawings and will be explained in greater detail below. In the said drawings: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a combined section and side view of two contact elements, which have been plugged together, in their receiving housings, 
     FIG. 2 shows a side view of a pin contact, 
     FIG. 3 shows a side view of a socket contact, 
     FIG. 4A shows a side view of a sleeve, 
     FIG. 4B shows a left side view of the sleeve shown in FIG.  4 A. 
     FIG. 5 shows a side view of a pin contact with an overlapping sleeve, 
     FIG. 6 shows a side view of a modified pin contact, and 
     FIG. 7 shows a detail enlargement of the front end of the modified pin contact. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Represented in FIG. 1, in a combined sectional and side view, are two contact elements which are plugged together, consist of a pin contact  1  and a socket contact  2  with an overlapping sleeve  3  in each case, and are inserted in their respective receiving housings  24  and  25 . Locking chambers  26 , in which the contact elements are arrested, are provided in the receiving housings. 
     Electrical conductors  28  are attached to the contact elements in each case, the contact element of the socket contact  2  being provided with a sealing sleeve  27  in order to protect this connection against contamination from outside. 
     A contact element constructed as a pin contact  1  is represented in FIG. 2 in a side view. 
     The contact element is subdivided into three regions: a contact-making section  4 , a fastening section  5  and a conductor-connecting section  6 , the sleeve  3  being positioned over the fastening section  5  in each case. The tubular fastening section  5  is provided with bores or clearances  7  in order to prevent twisting of the sleeve  3  on the fastening section in which the hook-shaped, inwardly pointing ends  17  of the spring flaps  15  engage at that point. 
     Immediately adjoining the fastening section, via a constricted portion  8 , is the contact-making section  4 , which is bent in a spherical or barrel-shaped manner and is formed from contact tongues  9 , of the pin contact  1  which is reduced in its diameter compared with the fastening section, so that the contact-making section of the pin contact  1  can be pushed into the contact-making section of the socket contact  2 . The contact tongues  9  of the contact-making section are separated from one another by slits  10 . Under these circumstances, provision is made for the slits  10  to reach beyond the contact-making section  4  and right into the fastening section  5 . 
     The spring properties of the contact tongues can be varied and adapted to the desired requirements, by the length of the slits and also by the shape of the contact tongues between the fastening section  5  and the constricted portion  8 . 
     The connection of an electrical conductor takes place via crimping flaps  11  for the strands which have been stripped of insulation, and also with the aid of fastening flaps  12  for holding the sheath of the cable. 
     The contact element which is constructed as a socket contact  2  is represented in FIG. 3 in a side view. 
     In this case, the tubular contact-making section  4  at the same time forms the fastening section  5  for the sleeve  3 . Adjoining this is the conductor-connecting region  6  which is constructed as a crimping-type connection for the purpose of receiving and fastening an electrical cable. 
     In the fastening section  5 , there are likewise provided, as in the case of the pin contact, bores  7  for the hook-shaped ends  17  of the spring flaps  15 , which bores prevent twisting of the sleeve on the said fastening section. Furthermore, stamped-out portions  13 ′ into which the arresting flaps  21  and  22  of the sleeve  3  are bent inwards, are provided on either side of the fastening section, as shown in FIG. 3 so that displacement of the sleeve in the axial direction is prevented. 
     The sleeve  3 , which is stamped from sheet-metal material and bent in the form of a tube, is represented in FIG. 4 in a side view. 
     Under these circumstances, the sheet-metal ends of the sleeve are bent inwards at the seam point  14  in such a way that the seam point ensures, as a supporting web, a minimum distance between the sleeve  3  and the fastening section  5 . In addition, inwardly pointing distance flaps  18 , and also inwardly directed impressed portions  19  are provided on the sleeve as further spacer elements. 
     On opposite sides of the sleeve  3 , outwardly bent spring flaps  15  with inwardly pointing, hook-shaped ends  17  are machined out of the material of the said sleeve. After the sleeve  3  has been slipped over the fastening section  5 , the hook-shaped ends  17  engage in corresponding recesses  7  in the said fastening section of the pin contact  1  or socket contact  2  and give rise to twist-proofing in the radial direction. 
     In the course of the final assembly of the contact elements  1  and  2  in the receiving housings  24  and  25  respectively, the folded portions  16  of the spring flaps  15 , which folded portions are bent virtually at right angles, latch into the particular contact chamber  26 . Furthermore, the sleeve has a number of arresting flaps  21  and  22  which are machined out of the sheet-metal casing and with the aid of which the sleeve  3  is locked in position in the axial direction on the fastening section of the pin contact and socket contact. 
     The pin contact is represented, with an overlapping sleeve  3 , in FIG. 5 in a side view. 
     That contact-making section  4  of the pin contact  1  which is to be pushed into the socket contact  2  is spherically shaped and provided with a slightly rounded but open point, so that, on the one hand, easy introduction of the pin contact into the socket is guaranteed and also, on the other hand, reliable contact is made possible, even in the case of oblique plugging-in. 
     The spring flaps  15  protruding out of the sleeve  3  form, with their folded portions  16 , latching elements which, when the contact element is pushed in, latch into the contact chambers  26  in the receiving housing and hold the contact element fast. 
     At the same time, the inwardly pointing, hook-shaped ends  17  of the spring flaps  15  protrude into bores or clearances  7  in the fastening section  5  and prevent radial twisting of the sleeve  3 . 
     Furthermore, arresting flaps  21  and  22  for axially arresting the sleeve on the fastening section of the contact element are provided on either side of the end of the said sleeve. 
     A modified pin contact  1 ′ without an overlapping sleeve  3  is represented in FIG. 6 in a side view. 
     That contact section  4  of the pin contact  1 ′ which is to be pushed into a socket contact—not shown here—is formed by the contact tongues  9  which are provided with outwardly directed embossed contact portions  32  and with a rounded point, so that easy introduction of the pin contact into the socket contact is guaranteed, and also reliable contact is made possible even in the case of oblique plugging-in. 
     In the front plugging-in region, the spherically arched contact tongues  9 , which are separated from one another by slits  10 , have a shape which is bent towards the central axis of the pin contact. 
     Under these circumstances, the points  30  of the contact tongues  9 , which points are of trapezoidal construction, are kept spaced apart from one another laterally. 
     What is achieved as a result of this is that the initial plugging-in operation is facilitated by gentle resilience until the trapezoidal points  30  touch one another, as a result of which a heightened spring tension is obtained during the rest of the plugging-in operation. Under these circumstances, the spring characteristic of the contact tongues  9  fastened at one end in the tubular fastening section  5 , which characteristic extends in a gentle manner at first, turns into a progressive, steep spring characteristic. 
     The progressive spring characteristic is brought about by the fact that the contact tongues abut at their two end points, namely in the fastening section  5  and also in the front plugging-in region, because of the trapezoidal points  30  which now touch each other, so that deformation remains possible only in the region of the contact tongues  9 , which are shaped spherically outwards and are provided with elevated embossed portions  32 . 
     This embodiment of the contact tongues acts in such a way as to be self-centring and to compensate for possible circularity errors in the counterplug. FIG. 7 shows, in an enlarged representation, how the front ends  30  of the contact tongues  9 , which front ends are disposed concentrically in relation to the centre point of the modified pin contact  1 ′ and point towards one another in the shape of a star, are spaced apart from one another (distance  31 ) when in the condition in which they are not plugged in.