Patent Publication Number: US-4544220-A

Title: Connector having means for positively seating contacts

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an electrical connector having means for assuring positive seating of contacts therein. 
     Pin and socket connectors of the type sold under the name MATE-N-LOK by AMP Incorporated have pin or socket contacts therein which are used to terminate wires coaxially crimped thereto. The contacts are situated in cavities through a housing constructed for mated connection with a complementary housing of another connector assembly. 
     There is described in U.S. patent application Ser. No. 307,997 now U.S. Pat. No. 4,443,048 a connector assembly as described above which employs a housing having cavities therethrough which receive the mating portions of respective contacts, and a retainer with passages therethrough which are assembled over respective wires. The retainer is latched to the rearward face of the housing to retain the contacts therein and assure that respective mating portions thereof are not unseated sufficiently to preclude mating with a complementary contact in a complementary connector. Improper seating is discovered by unlatching the retainer from the housing, the frictional force of the retainer on the wires causing improperly seated contacts to be withdrawn from the housing. Disadvantageously, the retainer can be fully mated to the housing while one or more contacts therein are not fully seated. 
     SUMMARY OF THE INVENTION 
     The electrical connector assembly of the present invention utilizes a housing and retainer designed to preclude the possibility of latching the housing and retainer together unless the contacts are fully seated. The retainer has passages therethrough and contact engaging means, in the form of sets of resilient fingers situated radially about respective passages, extending from the forward face thereof. The passages have a first diameter at the forward face and a second smaller diameter toward the distal ends of the fingers. The contacts each have a mating section at one end and an adjacent bearing section which spreads the fingers apart when it reaches the second diameter as the contact is inserted through the passage from the rearward face of the retainer. The fingers then snap back into position at a seating portion on the contact and the distal ends of the fingers bear on a shoulder between the bearing portion and seating portion to prevent the contact from backing up. When the fingers are spread apart, the distal ends would stub the rearward face of the housing rather than entering a respective cavity. 
     The contacts thus must be fully seated in the retainer else the retainer cannot be latched to the housing. Any contact not inserted sufficiently to spread the fingers would be readily visible at the rearward face of the retainer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective of two matable connector assemblies. 
     FIG. 2 is an exploded perspective of the pin housing, retainer, and pins. 
     FIG. 3 is a cross section of the pin housing and retainer. 
     FIG. 4 is a cross section of the retainer with pins inserted at three stages. 
     FIG. 5 is a partial section of an assembled pin connector. 
     FIG. 6 is a partial section of an assembled socket connector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows two matable connector assemblies 2, 6 according to the present invention. The socket connector 2 has tubular projections 3 profiled for reception in apertures 7 of pin connector 6, and a pair of latch arms 4 which engage latch 8 when the connectors are mated. The wires 70 which are terminated to the respective connectors 2, 6 are thus electrically connected. 
     FIG. 2 is an exploded perspective of a pin connector 6, which comprises a housing 10, retainer 20, and pin contacts 50. The housing 10 has a forward or mating face 12, a rearward face 13, and opposed external endwalls 11 and opposed external sidewalls 15 extending therebetween. The apertures 7 define entries to cavities 16 which also extend between faces 12 and 13. The retainer 20 has a forward or mating face 22, a rearward face 23, and opposed external endwalls 21 and opposed external sidewalls 25 extending therebetween. The sidewalls 25 have latch arms 24 extending therefrom which mate with latches 14 on sidewalls 15 when forward face 22 is flush against rearward face 13. The forward face 22 has contact engaging means extending therefrom, each means comprising a set of four engaging fingers 26 situated radially about a passage 30 which extends from the distal ends 27 of the fingers 26 to the rearward face 23 of the retainer 20. Both the housing 10 and retainer 20 are molded of Valox 357, a thermoplastic with good flexibility. (Valox is a trademark of the General Electric Company.) Pins 50 each comprise a mating portion 52 bounded by distal end 51 and smooth first shoulder 53, which leads to bearing portion 54, which extends to a relatively sharp second shoulder 55 facing away from distal end 51. Seating portion 56 is flanked by second shoulder 55 and third shoulder 57. Behind shoulder 57 the conductor crimp 58 grips strands 71 of wire 70 and strain relief crimp 59 grips the insulation 72. 
     FIG. 3 is a cross section of the housing 10 and retainer 20. The cavities 16 extend through housing 10 from forward face 12 to rearward face 13; each cavity has a forward section 17, an intermediate section 18, and a rearward section 19. Each set of spring fingers 26 is externally profiled to closely fit in rearward section 19 of a cavity 16 when the fingers are not in a deflected state. The passages 30 in retainer 20 extend from rearward face 23 through forward face 22 to the distal ends 27 of fingers 26. Each passage 30 comprises a body section 32 between faces 22, 23 and a first restriction 34 where the passage 30 necks down to an aligning section 35 defined by a first diameter at forward face 22. The aligning section 35 extends to a second restriction 36 where the passage 30 necks down to a spreading section 38 defined by a second diameter smaller than the first diameter. Referring again to FIG. 2, the bearing portion 54 of each pin 50 has a diameter substantially equal to but slightly smaller than the first diameter of aligning section 35. The bearing portion 54 is of necessity slightly smaller to facilitate entry, or in the alternative, may be an interference fit. 
     FIG. 4 shows the pins 50 in various stages of insertion in a housing 20, indicated by numerals 50, 50&#39; and 50&#34;. Pin 50 is shown with mating portion 52 protruding from fingers 26 and first shoulder 53 against second restriction 36 of passage 30. The bearing portion 54 is snug in aligning section 35. At this initial stage of insertion no substantial force is yet encountered and the crimp 58 is seen protruding from rearward face 23 so it is visually apparent that the pin 50 is not seated. 
     Pin 50&#39; depicts an important feature of the invention. As insertion progresses to this stage, each set of fingers 26 is urged radially apart by bearing section 54 of pin 50&#39;. At this stage of insertion, the fingers 26 are spread apart sufficiently by the force of bearing surface 54 against spreading section 38 to preclude mating of the retainer 20 to a housing 10 (FIG. 3), as the distal ends 27 would stub rearward face 13 rather than entering a cavity 16. A workman attempting to assemble a retainer 20 to a housing 10 would thus readily be aware of any pins not fully seated in a retainer, which situation could preclude mating of pins 50 to sockets 60 (FIG. 6) in the assembled connectors 2, 6. 
     Referring still to FIG. 4, pin 50&#34; is fully seated in a passage 30. The bearing portion 54 has passed completely through spreading section 38, allowing fingers 26 to return resiliently so that the distal ends 27 engage second shoulder 55. This prevents back-up of the pin 50&#34;. The third shoulder 57 of the pin 50&#34; is engaged by second restriction 36 in passage 30 to resist further forward movement of the pin. The fingers 26 have at this stage regained the external profile of the undeflected state, so that they can enter a corresponding cavity 16 in housing 10 (FIG. 3). 
     FIG. 5 is a partial cross-sectional view of an assembled pin connector 6, showing the pin contact 50 properly seated in retainer 20 and the retainer 20 properly engaged to housing 10, where it is held by latches. The mating portion 52 is coaxially located in forward section 17 of cavity 16 while bearing portion 54 is located closely in intermediate section 18. The positive seating means of the present invention is also used in the corresponding socket connector 2, shown properly assembled in the partial cross-sectional view of FIG. 6. Here the socket contact 60 has a mating portion or socket 62 coaxially located in tubular projection 3, which is profiled for entry in cavity 16, the mating portions 52, 62 likewise being telescopically mated. The latch arm 9 is for engaging the connector 6 to a panel board if desired. 
     The foregoing is exemplary and not intended to limit the scope of the claims which follow.