Abstract:
The female contact element comprising a rear shank designed to receive an electrical conductor and a front shank equipped with an elastic socket designed to receive a male contact element. The female contact element is formed from a one-piece tubular body in which the front shank and the rear shank are arranged, the elastic socket being fixed mounted in the front shank. A method for manufacturing such a female contact element.

Description:
RELATED APPLICATION  
       [0001]     This application claims priority to French Application No. FR 05 52433 filed Aug. 4, 2005.  
       TECHNICAL FIELD  
       [0002]     The invention relates to a female electrical contact element able to convey a high current flow. The invention also relates to a method of making such a female electrical contact element. The invention finds applications particularly in the field of electrical connectors designed to be utilized under severe conditions, for example in the field of avionics where temperature and vibration conditions may be extreme.  
       BACKGROUND ART  
       [0003]     A female electrical contact element comprising an elastic holding element that is able to maintain in position a male electrical contact element in a generally cylindrical form is already known.  
         [0004]     In particular, a female contact element in three parts is known from document FR 2 692 080, such as represented in  FIG. 1  of the prior art. A first part is comprised of a rear shank  2  designed to receive an electrical conductor such as a cable. The rear shank  2  is made of a material allowing said shank  2  to be crimped onto the electrical conductor. A second part  3 , or active part, is made of a material having high elasticity as well as good electrical conductibility. The active part  3  is designed to receive a male contact element, or terminal, in a generally cylindrical form. The active part  3  is, for example, formed from a socket divided up into longitudinal slots  4  in order to arrange a plurality of longitudinal tongues  5 . The tongues  5  are made in such a way as to present, at the location of a free end designed to receive the male terminal, an inner swelling. Said inner swelling is designed to be in contact with the male terminal when said terminal is inserted in the active part  3  of the female terminal  1 . Around the front part  3  is mounted a tube  6  joined on the common base  7  of the tongues  5 . The tube  6  supports the tongues  5  when they are deformed by the introduction of the male terminal into the active part  3 . When the male terminal penetrates between the tongues  5  of the active part  3  of the female terminal  1 , the deformation of the tongues  5  is such that the part lacking swelling of said tongues  5  takes the general form of an S, while the part with swellings remains straight with relation to the tube  6 . Each tongue  5  therefore is supported by the male terminal on the entire surface of its swelling, which allows good electrical conduction between the female terminal and the male terminal and maintenance of the male terminal in the active part  3  of the female terminal  1  to be ensured, even in the case of significant vibrations.  
         [0005]     However, such a female terminal is difficult to make inasmuch as the terminal is formed of three independent parts that are integral with each other. Therefore, it is necessary to develop each of the three parts of the female terminal very precisely in such a way as to guarantee a good connection between each of the pieces. Particularly, it is important to make the tube  6  with a very high precision, which must be joined on the active part  3 , since contact between the active part  3  and the tube  6  must be able to be made on the entire length of the tongues  5 .  
       SUMMARY OF THE INVENTION  
       [0006]     An object of the invention is to propose a female electrical contact element that is able to receive and maintain in connection position a male contact element, roughly cylindrical, whatever the connection conditions and particularly in the presence of high temperatures, significant temperature variations, significant vibrations, etc. Another object of the invention is to propose such a female contact element that is manufactured simply and inexpensively, not necessitating complex assembly.  
         [0007]     For this purpose, the invention proposes making a female terminal in two parts. A first part, or plastic connection part, ensures the connection between the female terminal and an electrical conductor such as a cable. A second part, or elastic active part, ensures contact pressure between the female terminal and an inserted male terminal, whatever the environmental conditions, for example during extreme vibrations and/or significant temperature variations. The plastic connection part is a one-piece body in which two cavities are arranged. The first cavity is designed to receive the cable, while the second cavity is designed to receive the elastic active part. Therefore, only the elastic active part is inserted. The second cavity, designed to receive the elastic active part, may be arranged roughly. The only area of the second cavity meant to be precise is the open end. Open end refers to the end by which the male terminal is introduced into the second cavity. In fact, the inner wall of the open end of the second cavity must come into contact with the lugs of the elastic active part when said lugs are moved apart by the presence of the male terminal. The area of contact between the lugs of the elastic active part and the inner wall of the second cavity must therefore be machined precisely. The area of contact must first allow entry of the male terminal into the elastic active part of the female terminal and, secondly, prohibit any clearance of said male terminal in the elastic active part. The plastic connection part and the elastic active part may be made of different conductive materials.  
         [0008]     Therefore, the object of the invention is a female contact element comprising a rear shank designed to receive an electrical conductor and a front shank equipped with an elastic socket designed to receive a male contact element, characterized in that it is formed from a one-piece tubular body in which the front shank and the rear shank are arranged, the elastic socket being fixed mounted in the front shank.  
         [0009]     According to the examples of embodiment of the invention, the female contact element may comprise part or all of the following additional features: 
    The elastic socket is fixed by an attaching end to a transverse wall of the tubular body separating the front shank and the rear shank.     The elastic socket is equipped with a plurality of longitudinal tongues.     The tongues of the elastic socket can be braced in the direction of the inner wall of the front shank, during introduction of a male contact element in the front shank.     An open end of the front shank is equipped with a centripetal flange able to form a mechanical stop for the tongues of the elastic socket.     The attaching end of the elastic socket is screwed into a screwing opening arranged in the transverse wall of the tubular body.     The attaching end of the elastic socket is fitted with a head in the screwing opening.    
 
         [0016]     The invention also relates to a method of making a female contact element characterized in that the method comprises steps consisting of: 
    Machining a tube at its two extremities in such a way as to arrange a front shank and a rear shank in an inner volume of the tube;     Inserting and fixing the elastic socket in the front shank.    
 
         [0019]     According to the examples of embodiment of the method of the invention, it is possible to add part or all of the following additional steps: 
    Machining the tube in such a way that a centripetal flange is arranged at the level of the end of the tube forming the open end of the front shank.     Fixing the elastic socket in the shank in such a way that a free end of the elastic tongues of the socket may abut against the centripetal flange.     Machining the front shank and the rear shank with a precision on the order of a tenth of a millimeter, and machining the open end of the shank, at the level of the centripetal flange, with a precision on the order of a hundredth of a millimeter.     Machining the front shank and the rear shank with a precision between 0.15 and 0.40 mm, plus or minus 0.05 mm and machining the open end of the shank, at the level of the centripetal flange with a precision between 0.015 and 0.035 mm, plus or minus 0.0005 mm.     Machining the tube in such a way as to arrange a transverse wall separating the front shank from the rear shank.     Arranging a screwing opening in the transverse wall of the tube.     Screwing the attaching end of the elastic socket into the screwing opening.     Fixing a head onto the attaching end of the elastic socket in the screwing opening.   
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]     The invention will be better understood upon reading the following description and examining the accompanying figures. The latter are presented for indication purposes only and in no way limit the invention. The figures represent:  
         [0029]      FIG. 1  is a sectional view of a female contact element from the prior art already described;  
         [0030]      FIG. 2  is a sectional view of an embodiment of a female contact element according to the invention;  
         [0031]      FIG. 3  is similar to  FIG. 2 , but depicting a male contact element received with the female contact element. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]      FIG. 2  represents a female contact element  10  according to an example of embodiment of the invention.  
         [0033]     The female contact element  10  comprises two distinct parts. A first part  11  is equipped with a body in a generally cylindrical tube shape in which are arranged a rear shank  12  and a front shank  13 . The rear shank  12  is, for example, designed to be crimped on an electric cable. The front shank  13  is designed to receive a complementary male contact element in a generally cylindrical shape (not represented in  FIG. 2 ). For this purpose, an elastic socket  14 , forming the second part of the contact element  10 , is fixed mounted in a cavity  15  of the front shank  13 . The rear shank  12  and the front shank  13  are separated from each other by a transverse wall  20 , diametrically traversing the first part  11 . The transverse wall  20  forms the bottom of the rear shank  12  and the front shank  13 .  
         [0034]     The elastic socket  14 , housed in the front shank  13 , comprises a base  16  from which a plurality of tongues  17  branch off. The tongues  17  extend from the base  16  in the direction of an open end  18  of the front shank  13 . The open end  18  of the front shank  13  is opposed to the bottom of the front shank  13  formed by the transverse wall  20 . The tongues  17  therefore have a free end  19 , directed towards the open end  18  of the front shank  13 , and a fixed end integral with the base  16 . The tongues  17  are regularly distributed on the entire external perimeter of the roughly circular base  16 . The free extremities  19  of the tongues  17  have a centripetal orientation, towards the center of the elastic socket  14 , with relation to the fixed extremities, in such a way that a diameter of said socket  14  at the level of the base  16  is strictly greater than a diameter of the socket  14  at the level of free extremities  19  of the tongues  17 . For example, the diameter of the socket  14  at the level of the free extremities  19  of the tongues  17  is strictly less than the diameter of the male contact element designed to be housed in the front shank  13 , and more precisely in the elastic socket  14 .  
         [0035]     The circular base  16  of the socket  14  is equipped, on a face directed toward the transverse wall  20 , with an attaching end  21 . The attaching end  21  is equipped with a thread in order to be screwed into a screwing opening  22  arranged in the transverse wall  20  of the tubular body  11 . The elastic socket  14  is screwed in the transverse wall  20  of the tubular body  11 . Therefore, fixed maintenance of the socket  14  in the cavity  15  of the front shank  13  is guaranteed. In order to ensure the irreversible fixation of the socket  14  in the front shank  13 , it is possible to fit the attaching end  21  with a head once the end is screwed into the screwing opening  22 . Therefore the thread of the attaching end  21  of the socket  14  is broken, which makes it impossible to unscrew said socket  14 . Of course, it is possible to connect the socket  14  by any other means in the cavity  15  of the front shank  13 . For example, it is possible to glue, solder the base  16  on the transverse wall  20  of the tubular body  11 .  
         [0036]     The socket  14  may, for example, by made of beryllium copper in order to present elasticity and conductivity properties that allow it to receive the male contact element and to guarantee good electrical contact between the two elements. The tubular body  11  may, itself, be made of a conventional copper alloy.  
         [0037]     It is important that the tongues  17  of the socket  14  have sufficient elasticity to allow passage of a male contact element  23  ( FIG. 3 ), as well as its maintenance in position in the front shank  13 .  
         [0038]     In  FIG. 3  can be seen a male contact element  23  housed in the socket  14  of the female contact element  10  of the invention.  
         [0039]     During the introduction of the male contact element  23  in the socket  14 , the male contact element spreads the tongues  17  apart in the direction of an inner wall  24  of the front shank  13 . The tongues  17  are braced in the direction of said inner wall  24 .  
         [0040]     The open end  18  of the front shank  13  is bordered by a centripetal flange, that is, directed towards a center of the cavity  15  of the front shank  13 . The presence of the centripetal flange  25  narrows the diameter of the front shank  13  at the level of the open end  18 , but, however, allows passage of the male contact element  23  in the front shank  13 .  
         [0041]     The centripetal flange  25  forms a mechanical stop  26  for the free end  19  of the tongues  17 . More precisely, when the male contact element  23  is housed in the socket  14 , the tongues  17  are braced in such a way that the free end  19  of said tongues  17  is stopped against  26  the centripetal flange  25 . The tongues  17  are also blocked at their two extremities.  
         [0042]     In the female contact element  10  according to the invention, only the area of abutment  26  must be machined in a very precise manner. In fact, the cavity  15  of the front shank  13  may be machined with a low precision, on the order of 0.15 to 0.40 mm, and more preferentially on the order of 0.2 to 0.3 mm, as with the cavity of the rear shank  12 . On the other hand, the area of the front shank  13  forming the abutment  26  must be machined in a very precise manner, with a precision on the order of 0.015 to 0.035 mm, and more preferentially on the order of 0.02 mm. In fact, the area of abutment  26  must allow blocking of the free end  19  of the tongues  17  in a position ensuring electrical conduction and the maintenance of the contact element  23  without clearance in the front shank  13 .  
         [0043]     Therefore, it is possible to machine the tubular body  11  from a solid copper alloy tube, for example, in such a way as to arrange the front shank  13  and the rear shank  12 . This machining step is relatively simple and may easily be performed automatically. The tubular body  11  is, for example, maintained in position by a clamp, while a tool hollows out a shank at each of its extremities. The two shanks  12 ,  13  obtained are separated from each other by a transverse wall  20  situated for example at the level of the central part of the tubular body  11 . One may therefore arrange a screwing hole  22  in the transverse wall  20 , designed to receive the attaching end  21  of the socket  14 . The socket  14  may, for example, be molded or also machined.  
         [0044]     After the first crude machining of the two shanks  13 ,  14  in the tubular body  11 , the area of abutment  26  is machined very precisely so that it is specifically adapted to the socket  14  and to the male contact element  23  that are designed to be housed in the front shank  13 . Specifically adapted means that the machining of the area of abutment  26  depends on the length of the tongues  17  and their radius of curvature when the male contact element  23  is introduced, and therefore also on the diameter and the length of penetration of the male contact element  23  in the socket  14 .  
         [0045]     Once machining of the tubular body  11  has ended, the socket  14  is fixed in the front shank  13  in such a way as to obtain the female contact element  10  of the invention.  
         [0046]     The number of steps necessary for constructing such a female contact element  10  according to the invention is therefore low, which allows the risks of poor mounting or poor machining of the female contact element  10  to be reduced.