Patent Publication Number: US-4220388-A

Title: Electrical connector and contact and housing therefor

Description:
This invention relates to an electrical connector comprising a receptacle contact contained in a one-piece insulating housing and defining a male-contact-receiving passage. 
     Such connectors are well known in many forms, the receptacle contact being, for example, for receiving a round pin or a flat tab male contact. 
     Known connectors generally provide the required connection properties such as contact force between the receptacle contact and a male contact mated therewith, but many suffer from the disadvantage that they require a relatively high insertion force for mating of the male contact with the receptacle contact. 
     Many connectors are known, which provides a relatively low insertion force, but such connectors generally utilize a housing not of one-piece construction, but having relatively moving parts with relative movement between the parts serving to increase the effective cross-sectional area of the male-contact-receiving passage of the receptacle contact such that the male contact can be inserted into the passage with no appreciable resistance. 
     However, such known low insertion force connectors are relatively complex in construction and are thus also relatively expensive to manufacture. 
     According to this invention an electrical connector comprising a receptacle contact contained in a one-piece insulating housing and defining a male-contact-receiving passage, is characterised in that the receptacle contact is formed with at least one outwardly directed projection engageable with a surface of the housing on movement of the receptacle contact relative to and within the housing, such engagement effecting an increase in the effective cross-sectional area of the male-contact-receiving passage of the receptacle contact. 
     Thus, the connector of this invention has the advantage that it provides for a low insertion force on mating of a male contact with the receptacle contact by the use of a single and thus relatively cheap one-piece housing of the type used with known connectors having a relatively high insertion force. 
     Preferably the receptacle contact is formed with two outwardly directed projections each engageable with an individually associated surface of the housing on movement of the receptacle contact relative to and within the housing, such engagement serving to urge the two projections away from each other thereby to effect an increase in the effective cross-sectional area of the male-contact-receiving passage of the receptacle contact. 
     The relative movement between the receptacle contact and the housing can be either along the axis of the male-contact-receiving passage of the receptacle contact, or otherwise about this axis. 
     Preferably the relative movement between the receptacle contact and the housing is caused by engagement between a male contact being mated with the receptacle contact when the male contact is moved relative to the housing and into the male-contact-receiving passage of the receptacle contact. 
     The receptacle contact can be formed with a locking projection arranged to engage in a hole or recess in a male contact when mated with the receptacle contact thereby to prevent withdrawal of the male contact from the male-contact-receiving passage in the receptacle contact by forces applied directly to the male contact and the receptacle contact. 
     With such a locking connector relative movement between the receptacle contact and the housing can be used to release the locking projection on the receptacle contact from the hole or recess in the male contact if the locking projection is positioned on the receptacle contact so as to be moved outwardly of the male-contact-receiving passage on increasing of the effective cross-sectional area of the male-contact-receiving passage of the receptacle contact. 
     Preferably the relative movement used to effect the release is in the opposite sense to that which occurs on mating of a male contact with the receptacle contact since then the release can be effected by a force applied to the housing in the direction of insertion of a male contact into the receptacle contact while a similar force applied to the receptacle contact only will not effect the release. 
    
    
     Two connectors according to the invention will now be described by way of example with reference to the drawings, in which: 
     FIG. 1 is a perspective view of a receptacle contact for use in a first connector according to the invention; 
     FIG. 2 is a section on the line II--II in FIG. 1; 
     FIG. 3 is a perspective view, with part broken away, of a housing for use with the receptacle contact of FIGS. 1 and 2; 
     FIG. 4 is a plan view, with part broken away, of the housing of FIG. 3; 
     FIG. 5 is a section on the line V--V in FIG. 4; 
     FIG. 6 is a section on the line VI--VI in FIG. 5; 
     FIG. 7 is a section on the line VII--VII in FIG. 5; 
     FIG. 8 is a vertical longitudinal sectional view through a connector formed from the receptacle contact of FIGS. 1 and 2 and the housing of FIGS. 3 to 7, together with a male contact for mating therewith; 
     FIG. 9 is a view similar to FIG. 8 but showing the connector with the male contact being mated therewith; 
     FIG. 10 is a perspective view of a receptacle contact for use in a second connector according to the invention; 
     FIGS. 11 and 12 are views illustrating how the receptacle contact of FIG. 10 locks onto a complementary male contact; and 
     FIG. 13 is a perspective view of a housing for use with the receptacle contact of FIGS. 10 to 12. 
    
    
     The receptacle contact shown in FIGS. 1 and 2 is for mating with a flat tab male contact, and comprises a receptacle portion 1 and a wire-connection portion 2 integrally formed from sheet metal. 
     The wire-connection portion 2 comprises a first ferrule 3 for crimping about a bared end portion of the conductive core of an insulated wire (not shown), and a second ferrule 4 for crimping about the insulation of the wire, in known manner. 
     The receptacle portion 1 comprises a base 5 having edge portions 6 rolled in over the base 5 and having their free ends 7 directed towards the base 5. 
     The base 5 and edge portions 6, 7 of the receptacle portion 1 together define a male-contact-receiving passage 8 which will receive a flat tab male contact to be gripped between the base 5 and the edges 7 of the edge portions 6, in known manner. 
     A projection in the form of an ear 9 is struck from each of the edge portions 6 to extend away from the base 5. 
     A retention projection 10 is pushed out of the base 5 at the junction between the receptacle portion 1 and the wire connection portion 2. 
     In use of the receptacle contact shown in FIGS. 1 and 2 a flat tab male contact is inserted between the base 5 and the edges 7 of the edge portions 6, to be gripped therebetween due to the resilience of the receptacle portion 1. Such insertion acts to urge the edges 7 of the edge portions 6 away from the base 5, thus increasing the effective cross-sectional area of the passage 8 in the receptacle portion to admit the male contact. The force necessary for insertion of the male contact is thus dependent upon the contact force operative between the male contact and the receptacle contact when mated, and thus with known arrangements a desirable decrease in the necessary insertion force can be achieved only by decreasing the contact force, this not normally being desirable or possible. 
     The above described contact overcomes this problem by the provision of the projections 9. If the projections 9 are urged relatively away from each other transversely of the passage 8, then the edges 7 will be urged away from the base 5, thus increasing the effective cross-sectional area of the passage 8. If this is done prior to insertion of a male contact into the passage 8, then the male contact can be inserted with no, or at least a substantially reduced, resistance, whereafter release of the projections 9 will allow the edges 7 to grip the male contact with a high contact force. 
     The receptacle contact above described can therefore provide a given contact force with a considerably less insertion force being necessary than known receptacle contacts of similar construction. 
     Clearly the force necessary to urge the projections 9 apart can be provided by direct engagement with the user&#39;s fingers or by means of a suitable tool of the reversely-acting pliers type, but if the receptacle contact is to be contained in an insulating housing then it is convenient to use the housing to provide the necessary engagement with the projections 9. 
     Such a housing for use with the receptacle contact of FIGS. 1 and 2 will now be described with reference to FIGS. 3 to 7 also. 
     The housing is a one-piece moulding of electrically insulating plastics material, and is generally rectanguloid in shape, having a bottom wall 11, a top wall 12, and side walls 13, the housing being open at its axial ends. 
     An elongate recess 14 is formed in the inner surface of the bottom wall 11, the recess 14 being open to one, rearward end of the housing. 
     The top wall 12 is formed in its inner surface with two grooves 15 open to the other, forward end of the housing, the outer surfaces 16 of the grooves 15 extending parallel to the longitudinal axis of the housing, while the inner surfaces thereof have a first part 17 extending from the forward end of the housing parallel to the outer surfaces 16, and a second inner part 18 extending from the first part 17 towards the outer surface 16, the grooves 15 each terminating in a shoulder surface 19 facing the forward end of the housing. The top wall 12 decreases in thickness outwardly from the shoulder surfaces 19 towards the rearward end of the housing, over portions in line with the grooves 15, to form tapered grooves 20. 
     To form an electrical connector, the receptacle contact shown in FIGS. 1 and 2 is crimped in known manner to an insulated wire 21 (FIGS. 8 and 9) and is then inserted into the housing of FIGS. 3 to 7 from the rearward end thereof. 
     On such insertion the retention projection 10 of the receptacle contact is received in the recess 14 in the bottom wall 11 of the housing and limits forward movement of the receptacle contact relative to the housing by engagement with the closed inner end of the recess 14. The projections 9 of the receptacle contact are received in the grooves 20 in the top wall 12 of the housing, and are urged downwards towards the bottom wall 11 of the housing by engagement with the top wall 12 until they pass the shoulder surfaces 19 and are received in the grooves 15 in top wall 12. 
     The receptacle contact and housing then form a connector as shown in FIG. 8, with the receptacle contact secured in the housing but capable of axial movement relative thereto between end positions determined by engagement between the retention projection 10 and the end of the recess 14, and by engagement between the projections 9 and the shoulder surfaces 19, respectively. 
     A flat tab male contact 22 can then be mated with the receptacle contact to establish connection to the wire 21 connected to the receptacle contact. 
     Initially the receptacle contact is in a forward position, as shown in FIG. 8, relative to the housing. 
     As the male contact 22 is inserted into the passage 8 of the receptacle contact, its tapered leading end engages between the base 5 and the edges 7 of the edge portions 6, and meets a resistance to insertion which resistance must, as discussed above, be overcome by movement of the edges 7 away from the base. 
     This resistance causes the receptacle contact to move back relative to the housing as shown in FIG. 9, during which movement the projections 9 of the receptacle contact engage the surfaces 18 of the housing, this engagement, due to the diverging arrangement of the surfaces 18, causing the projections 9 to be urged away from each other. Such movement of the projections 9 causes the edges 7 to be moved away from the base 5, and thus increases the effective cross-sectional area of the passage 8 receiving the male contact 22. Rearward movement of the receptacle contact relative to the housing is limited, as discussed above, by engagement of the projections 9 with the shoulder surfaces 19 of the housing. 
     The engagement between the projections 9 of the receptacle contact and the surfaces 18 of the housing thus serves to assist the male contact 22 in moving the edges 7 away from the base 5, and the force necessary for insertion of the male contact 22 into the passage 8 is therefore less than would otherwise be required. 
     After insertion of the male contact 22 the resilience of the receptacle portion 1 causes the edges 7 to engage the male contact 22 which is thus gripped between the edges 7 and the base 5. On release of the housing, reaction forces between projections 9 and the surfaces 18 cause the housing to move rearwards on the receptacle until the retention projection 10 engages the closed end of the recess 14, the male contact 22 then being gripped with the full, necessary contact force. 
     Referring now to FIGS. 10 to 12, the receptacle contact here shown is similar to that shown in FIGS. 1 and 2, and corresponding parts have the same references. 
     This receptacle contact does not however have a retention projection (10 in FIGS. 1 and 2), but the edges 7 of the edge portions 6 are each provided with a tang 23 projecting towards the base 5, and providing a shoulder surface 24 facing the wire connection portion 2, and a sloping forward facing surface 25. 
     This receptacle contact is for use with a flat tab male contact 22 having a hole 26 (or a recess) in its upper surface into which the tang 23 will extend when the male contact 22 is mated with the receptacle contact. 
     The male contact 22 thus becomes locked in the receptacle contact, withdrawal being restrained by engagement between the shoulder surface 24 of the tang 23 and the edge of the hole 26. 
     By urging the projections 9 apart the male contact 22 can be inserted with a low insertion force, as described above for the receptacle contact of FIGS. 1 and 2. 
     When it is required to release the male contact 22 from the receptacle contact the projections 9 are again urged apart, this moving the edges 7 of the edge portions 6 away from the base 5, and thus moving the tang 23 out of the hole 26 in the male contact 22, whereby the male contact 22 can be withdrawn from the receptacle contact. 
     Referring now to FIG. 13 also, this shows a housing for use with the receptacle contact of FIGS. 10 to 12 to form a connector providing for a low male contact insertion force, positive locking of the connector to a mated male contact, and easy release of the connector from a mated male contact when required. 
     The housing is moulded from electrically insulating plastics material, and is generally rectanguloid in shape having a bottom wall 11, top wall 12, and side walls 13. The axial ends of the housing are open. 
     The top wall 12 is formed with two aligned through holes 27 each having a straight outer surface 28 extending parallel to the longitudinal axis of the housing, a straight forward shoulder surface 29 and a straight rearward shoulder surface 30 extending at right-angles to the outer surface 28, and an inner surface having a straight central portion 31 extending parallel to the outer surface 28 and end portions 32 and 33 extending from the central portion 31 towards the outer surface 28 to meet the shoulder surfaces 29 and 30. 
     The relative sizes of the housing and the receptacle contact are such that when the receptacle contact is inserted into the housing from the rearward (right-hand) in FIG. 13) end of the housing the base 5 of the receptacle contact engages the bottom wall 11 of the housing and the projections 9 engage the top wall 12 of the housing such that the projections are urged downwards towards the base 5, resiliently deforming the edge portions 6. 
     When the receptacle contact is fully inserted into the housing the projections 9 reach the holes 27 and the resilience of the edge portions 6 urges the projections 9 into the holes 27. 
     The receptacle contact is then freely received in the housing but is secured therein so as to be capable of limited axial movement relative thereto, by engagement of the projections 9 with the shoulder surfaces 29 or 30 of the holes 27. 
     As described above for the connector of FIGS. 1 to 9, when a flat tab male contact 22 is mated with the connector the receptacle contact is urged backwards relative to the housing, and the projections 9 engage the surfaces 33 of the holes 27. The projections 9 are thus urged apart, thereby increasing the effective cross-sectional area of the male-contact-receiving passage 8 of the receptacle contact to allow insertion of the male contact 22 with a low insertion force. 
     The male contact 22 is inserted until the tangs 23 enter the hole 26 therein, as described above, to lock the connector to the male contact 22. 
     The connector is then such that axial forces applied to wires connected to the receptacle contact and/or the male contact 22 will not separate the connection. 
     When it is required to release the male contact 22 from the receptacle contact the housing is pulled backwards away from the male contact 22, and thus moves backwards relative to the male contact 22 and thus to the receptacle contact locked to the male contact 22. This movement causes the surfaces 32 of the holes 27 to engage the projections 9 and urge them apart, this, as described above, urging the edges 7 of the edge portions 6 away from the base 5 and thus lifting the tangs 23 out of the hole 26 in the male contact 22 which can then be withdrawn from the receptacle contact. 
     Although the connectors according to the invention, described above, are for mating with flat tab male contact, it will be appreciated that connectors according to the invention can be for mating with other types of male contact, for example circular cross-section pins. 
     Further, although in the connector described with reference to FIGS. 10 to 13, the holes 27 in the housing are open such that the projections 9 of the receptacle contact are accessible therethrough, it will be appreciated that these holes 27 can be covered if necessary or desirable, for example by means of a separate cover member or by not making the holes 27 through holes but merely recesses in the inner surface of the top wall 12 of the housing. To facilitate moulding of such a housing with recesses the housing can be split along one of the side walls 13 with the other side wall 13 serving as a hinge and the split side wall being provided with latching means to latch the housing about the receptacle contact. Such a housing would also facilitate insertion of the receptacle contact into the housing.