Electrical connection device
BACKGROUND OF THE INVENTION 
     This invention relates, generally, to an electrical connection device. More particularly, it relates to an electrical connection device of the type including an electrical socket member and an electrical mating pin. 
     Connection devices of this type, consisting of male and female connector parts, provide extremely secure electrical connections which can only be disengaged with considerable effort. 
     Such a connection device has been disclosed in GB 2 128 039 A. The contact area of the connector socket, intended to accept a round mating pin, exhibits four tines. An annular groove formed into the tines retains a driver member made of heat-recoverable metal against the contact area of the socket so that the driver member cannot become detached. 
     In its second functional position, after inward recovery, the driver member shrinks to exert pressure on the tines and thus to form a pressure connection between the tines and the mating pin. 
     The present invention aims to improve on this system by creating an electrical connection device in which the driver member creates a keyed-in as well as a pressure connection between the socket and the mating pin. 
     The particular advantage of the improved system lies in the fact that, in addition to the high electrical contact reliability assured by the high contact pressure exercised through the driver members, the keyed-in system offers extra high resistance to unwanted disengagement resulting from mechanical loads such as push-pull forces or vibration. 
     Furthermore, it is particular advantageous to provide a connection device which includes a heat-recoverable driver member with a locking means which is able to prevent the driver element from acting on the device before it is appropriate. 
     This locking means prevents the driver element from shrinking and therefore narrowing the socket should it be exposed to heat during, for example, shipping or storage, and therefore guarantees that the mating pin can still be inserted easily when desired. 
     It is, of course, also possible to incorporate such a locking means into a connection device whose mating pin does not exhibit a groove for the reception of the driver element. Such an application would remain within the framework of this patent. 
     Accordingly, it is the object of the invention to provide a new and improved electrical connection device of the type including an electrical socket member and an electrical mating pin. 
     Other objects and features of the invention will become apparent from the following description when read in conjunction with the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1a shows an electrical connection device with the driver element in its second functional position after recovery, 
     FIG. 1b is a cross section of the device taken through the line A--A shown in FIG. 1a, 
     FIG. 2a is a schematic side view of a further electrical connection device with the driver element in its second functional position after recovery, 
     FIG. 2b is a cross-section of the device originally shown in 2a, 
     FIG. 2c is a frontal view of the device originally shown in 2a, 
     FIG. 3a is a partially cross-sectioned side view of a third electrical connection device, 
     FIG. 3b is a birds-eye view of the device originally shown in 3a, 
     FIG. 3c is a frontal view of the device originally shown in 3a, with its locking element open and with the driver member detached, 
     FIG. 3d is a frontal view of the device originally shown in 3a, with its locking element in the locked position and with the driver member attached, and 
     FIG. 3e is a frontal view of the device originally shown in 3a, with the mating pin inserted and with its locking element open to permit the driver member to exert pressure on the mating pin. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As can be seen from the drawings, an electrical connection device of the type described here includes a socket member 1, generally manufactured by means of stamping and bending processes which exhibits a termination area 2 for the connection of an electrical cable connected via a base 1a to a contact area 4 intended to receive a mating pin 3. The contact area 4 also is provided with a separate driver member 5 of heat recoverable material in the form of a closed ring. 
     A first embodiment of a connecting device according to the present invention will now be described. As shown particularly in FIGS. 1a and 1b, the contact area 4 of socket member 1 exhibits a round cross-section and is intended to receive a round mating pin 3. The socket member 1 and its termination area 2 and contact area 4 all lie in an axial plane. Contact area 4 exhibits two basically rectangular tines 6 which are adapted cylindrically to the round contour of mating pin 3. Tines 6 are produced by the stamping-out of two basically rectangular cutouts 7 extending from the end opening of contact area 4. 
     Cutouts 7 are dimensioned in such a way that the width of each tine 6 is at least slightly less than the diameter of mating pin 3. 
     Driver member 5 is retained against contact area 4 by retaining wedges 8 formed onto tines 6 so that driver member 5 cannot be detached. Each of the two tines 6 exhibits a first wedge 8a with its widest part facing towards termination area 2 and a second wedge 8b which has its widest part facing towards the open end of socket member 1. Driver member 5 surrounds contact area 4 approximately one third of the way up tines 6, measured from the end which is opposite the termination area. Both shorter sides of the oval-shaped driver member 5 lie against a tine 6, the tines lying opposite each other. Mating pin 3 is provided with an annular recess 9 in the form of a continuous groove around its circumference. Both long sides of driver member 5 partially fit into annular recess 9. The depth of annular recess 9 is such that driver member 5 does not rest on the bottom of it when in its second functional position, shown in FIGS. 1a and 1b. 
     At the end of socket member 1 which is nearest termination area 2 there is a retaining tongue 10, which fits into an equivalent tongue recess 11 in mating pin 3. 
     In order to create a connection device such as that described here, the closed-ring oval driver member 5 of heat-recoverable metal is brought into its first functional position by means of stretching. The stretched driver member 5 is pushed onto the contact area 4 of socket member 1 from the end which lies opposite the termination area. In this process, driver member 5 must be pushed over the first retaining wedges 8a, which in turn pushes the tines 6 towards each other. When driver member 5 comes to rest against the second retaining wedges 8b, both tines 6 spring back to their original position, so that driver member 5 cannot slip from its intended position round contact area 4, between wedges 8a and 8b. 
     In this first functional position, contact area 4 is only loosely surrounded by driver member 5, i.e. driver member 5 is so dimensioned as to be slightly larger in circumference than socket member 1. No pressure is therefore exerted on tines 6. 
     Socket member 1 with driver member 5 is then aligned with mating pin 3 so that electrical contact can be made. In order to secure optimum contact, socket member 1 is pushed over mating pin 3 until retaining tongue 10 fits into tongue recess 11. 
     At this stage mating pin 3 and socket member 1 are ready for final connection. Now driver member 5 is heated with a suitable heating means, whereby driver member 5 recovers inwardly to assume its original form. During and after the recovery, the two shorter sides of oval driver member 5 are pressed hard against tines 6, so that these in turn press hard against mating pin 3. In addition, the two longer sides of driver member 5 fit partially into annular recess 9 in mating pin 3. 
     By means of this process a two fold mechanical connection is formed between mating pin 3 and socket member 1--on the one hand a pressure connection, and on the other hand a keyed-in connection. 
     In FIGS. 2a, 2b and 2c, there is illustrated a second embodiment of the invention. Contact area 4 of socket member exhibits a round cross section and is intended to receive an equivalent mating pin 3 with round cross section. Socket member 1 consists of a termination area 2 for the connection of an electrical cable extending in a radial direction and a contact area 4 extending axially away from base section 1a of termination area 2. 
     Contact area 4 consists principally of two longitudinal tines 6, whose contour is adapted to the round cross section of mating pin 3. The two tines 6 are formed by the stamping-out of basically rectangular cutouts 7. Starting from that end of contact area 4 which is not directly joined to base section, 1a, the initial portions 7a of cutouts 7 are dimensional in such a way that the width of each tine is at least slightly less than the diameter of mating pin 3. Continuing towards the end which is joined to base section 1a, further portions 7b of cutouts 7 follow which are so dimensioned that the width of each tine is considerably greater than the diameter of mating pin 3. 
     The beginnings of the wider parts of tines 6 serve as stops 12 for driver member 5 and thus define its position. 
     Each of the two tines 6 exhibits a retaining wedge or lobe 8, formed onto the tines and facing outward. Driver member 5 is securely retained at contact area 4 between retaining lobes 8 and stops 12. Tines 6 are shaped in such a way that driver member 5 is held near that end of contact area 4 which is not directly joined to base section 1a, each shorter side of oval driver member 5 lies against one of the two tines, which face each other. Mating pin 3 exhibits an annular recess 9 in the form of a groove. Both longer sides of driver member 5 partially fit into annular recess 9. The depth of annular recess 9 is such that driver member 5 does not rest on the bottom of it when in its second functional position, shown in FIGS. 2a, 2b and 2c. 
     A stop tab 13 is formed onto the end of contact area 4 which is not directly joined to base section 1a which limits the depth of insertion of mating pin 3. 
     In order to create a connection device of this second type described here, the closed-ring oval driver member 5 of heat-recoverable material is brought into its first functional position by means of stretching. The stretched driver member 5 is pushed onto the contact area 4 of socket member 1 from the end which is not directly joined to base section 1a. In this process, driver member 5 must be pushed over retaining lobes 8, which in turn pushes the tines 6 towards each other. When driver member 5 comes to rest against stops 12, both tines 6 spring back to their original position, so that driver member 5 cannot slip from its intended position around contact area 4, between stops 12 and retaining lobes 8. 
     In this first functional position, contact area 4 is only loosely surrounded by driver member 5, i.e. driver member 5 is so dimensioned as to be slightly larger in circumference than socket member 1. 
     No pressure is therefore exerted on tines 6. Socket member 1 with driver member 5 is then aligned with mating pin 3 so that electrical contact can be made. In order to secure optimum contact, socket member 1 is pushed from its base 1a onto mating pin 3 until the end of mating pin 3 comes to rest against stop tab 13 at the opposite end of the socket members 1. The inherent resilience of tines 6 holds socket member 1 on mating pin 3. Now driver member 5 is heated with a suitable heating means, whereby driver member 5 recovers inwardly to assume its original form. 
     During and after the recovery, the two shorter sides of oval driver member 5 are pressed hard against tines 6, so that these in turn press hard against mating pin 3. In addition, the two long sides of driver member 5 partially fit into annular recess 9 in mating pin 5. By means of this process a twofold mechanical connection is formed between mating pin 3 and socket member 1--on the one hand a pressure connection, and on the other hand a keyed-in connection. 
     Driver member 5 can also of course take the form of a mechanical clamping device, such as a clamping ring or clamping blocks. 
     A description of a third embodiment of the invention follows, as shown in FIGS. 3a, 3b, 3c, 3d and 3e. The cross section of the contact area 4 of electrical socket member 1 consists of two sections of a ring and is intended to make contact with mating pin 3, which has a suitable circular cross section. Socket member 1 consists of a termination area 2 for the connection of an electrical cable running in a direction which is radial in relation to mating pin 3, and a contact area 4 extending axially away from the base section 1a of termination area 2. Contact area 4 consists basically of two longitudinal tines 6, which are adapted to the round contour of mating pin 3 and formed by the stamping out of basically rectangular cutouts 7. Starting from that end of contact area 4 which is not directly joined to base section 1a, the initial portions of cutouts 7a are dimensioned in such a way that the width of each tine is at least slightly less than the diameter of mating pin 3. Continuing towards, the end which is joined to base section 1a, a further portion 7b follows where cutouts 7 are dimensioned so that the width of each tine is considerably greater than the diameter of mating pin 3. The beginnings of the wide parts of tines 6 serve as stops 12 for driver member 5 and thus define its position. 
     Each of the two tines 6 exhibits a retaining lobe 8, formed onto the tines and facing outward. Driver member 5 is securely held at contact area 4 between retaining lobes 8 and stops 12. Tines 6 are shaped in such a way that driver member 5 is held near that end of contact area 4 which is not directly joined to base section 1a. Each shorter side of driver member 5 lies against one of the two tines, which face each other. Mating pin 3 exhibits an annular recess 9 in the form of a groove. Both longer sides of driver member 5 partially fit into annular recess 9. A locking element 14 is formed onto the end of each of the tines in one piece. These locking elements 14 are finger-shaped and their ends meet directly when in the locked position. 
     In order to create a connection device of this third type, the closed-ring oval driver member 5 of heat-recoverable material is enlarged by stretching. It is then pushed onto the contact area 4 of socket member 1 from the end which is not directly joined to base section 1a. As can be seen in FIG. 3c, locking elements 14 are initially positioned at an angle to socket member 1 so that they serve as a guide and assembly aid for driver member 5. Driver member 5 must first be pushed over retaining lobes 8, which in turn pushes tines 6 towards each other. When driver member 5 then comes to rest against stops 12, both tines 6 spring back into their original position and driver member 5 is held securely against contact area 4 between stops 12 and retaining lobes 8. Now, as can be seen in FIG. 3d, locking elements 14 are bent back in such a way that their free ends come to rest directly against one another. This is the locked position. In this first functional position, contact area 4 is loosely surrounded by driver member 5, which means that no pressure is exerted on tines 6 under normal circumstances. If, however, temperatures of, for example, over 75° C. are encountered during storage or transport of the connectors, the inward recovery process of driver member 5 is initiated. Locking elements 14 in their locked position prevent driver member 5 from shrinking in response to the higher temperatures and therefore also prevent any compression of contact area 4. Locking elements 14 are formed in such a way that they particularly prevent shrinking of the long sides of oval driver member 5. 
     Equipped with locking elements 14, socket member 1 can be easily connected to mating pin 3, even if the heat recovery process of driver member 5 has already been initiated. In order to secure optimum contact, socket member 1 is pushed from its base onto mating pin 3 until the end of mating pin 3 comes to rest against the underside of locking elements 14. Socket member 1 is held precisely in position over mating pin 3 by means of the inherent resilience of tines 6 and retaining extensions 15 which are formed onto base 1. Retaining extensions 15 fit into an equivalent recess in mating pin 3. 
     As can be particularly seen in the FIG. 3e, the locked position of locking elements 14 is now released by taking the ends of locking elements 14 out of direct alignment. In order to achieve this, at least one of locking elements 14 is bent. If the inward recovery process of driver member 5 should already have been initiated as described above, its inherent force will now be freed to act on tines 6, pressing them against mating pin 3. However, driver member 5 is in any case now finally subjected to temperatures well above 75° C., which continues inward recovery process. The two shorter sides of driver member 5 are pressed hard against tines 6, so that these in turn press hard against mating pin 3. In addition, the two longer sides of driver member 5 fit partially into annular recess 9 in mating pin 3. In this way a twofold mechanical connection is formed between mating pin 3 and socket member 1--on the one hand a pressure connection, and on the other hand a keyed-in connection. 
     Obviously the fixing technique which is described here as applied to a two-component (pin-and-socket) connector can also be transferred to other technical applications, while still remaining within the framework of this patent. An example would be the application of the technique to hub and axle technology.