Snap-in contacts for electrical connectors

Sept. 5, 1961 r. h. ellis etal 2,999,221

SNAP-IN CONTACTS FOR ELECTRICAL CONNECTORS

<img file="US2999221A_D0001.tif" />

<img file="US2999221A_D0002.tif" />

/Jrro/SNeys.

Sept. 5, 1961 r. _H. ellis etal 2,999,221

SNAP-IN CONTACTS FOR ELECTRICAL CONNECTORS

Filed Aug. 2, 1960 2 Sheets-Sheet 2

<img file="US2999221A_D0003.tif" />

<img file="US2999221A_D0004.tif" />

<img file="US2999221A_D0005.tif" />

INVENTORS.

HoG&amp;E JI» J&amp;e/V£ST Wb IKC/F/-//.

<img file="US2999221A_D0006.tif" />

Ρ?γτο/ζλ/ευ·5

United States Patent Office

2,999,221

Patented Sept. 5, 1961

2,999,221

SNAP-IN CONTACTS FOR ELECTRICAL CONNECTORS

Roger H. Ellis, Arcadia, and Ernest W. Kuehl, San Fernando, Calif., assignors to Cannon Electric Company, Los Angeles, Calif., a corporation of California

Filed Aug. 2, 1960, Ser. No. 46.940

Claims. (Cl. 339—176)

The present invention relates generally to electrical connectors having mating connector members with pin and socket contact elements or terminals mounted therein, respectively, and the invention relates more particularly to a novel electrical connector construction wherein the contact elements or terminals can be snapped into and out of their operative positions in the connector bodies.

In many electrical connector applications it would be advantageous to be able to snap the pin and socket contact terminals into and out of their operative positions in the connector body portions. For example, where a connector has numerous terminals, and especially in the case of a miniature connector where the terminals are close to each other, the work involved in crimping or soldering the ends of the conductor wires to the terminals is intricate and tedious, and it is therefore desirable to be able to attach the wires to the terminals, as by crimping or soldering, on the bench, and thereafter to snap the terminals into their operative positions in the connector body portions. It is desirable to be able to remove the individual contact terminals from the connector portions without completely disassembling the connector portions for a number of reasons, such as to permit correction of circuit errors, or to allow modification of the electrical circuits embodying the connector without having to use a new connector and without requiring re-attachment of the conductor wires to the individual contact terminals. Removability of the individual contact terminals from the connector body portions further permits replacement of damaged connector parts, including damaged terminals, without requiring that all of the individual contacts be replaced, and without in any way disturbing the circuitry embodying the connector.

One of the principal problems which must be contended with in connection with contact terminals which are adapted to be inserted into a connector body after the ends of the conductor wires have been connected to the terminals as by crimping or soldering, is to provide engaging means between the individual terminals and the connector body which will securely hold the terminals in fixed positions in the body during engagement and disengagement of the connector members. In order to prevent undesired shifting or dislodging of individual terminals during engagement or disengagement of the connector members, prior art devices of this general type have provided engaging means between the individual terminals and the connector body portions which cause the terminals to be permanently locked in their operative positions in the body portions so that the terminals could not be removed without dismantling or disassembling the connector members or without using special removal tools which require undesirable working clearances in the connector members.

Because of these and other problems in the art, it is an object of the present invention to provide an electrical connector having pin and socket terminals which may be snapped into and out of their operative positions in the connector body portions without dismantling or disassembling the connector members and without requiring special tools.

Another object of the present invention is to provide an electrical connector having pin and socket contact terminals which are insertable from the rear or conductor ends of the connector body portions into axial bores through the connector body portions, the pin and socket terminals each having an annular groove thereon in which is mounted a resilient retaining ring, the retaining ring 5 being compressed radially-inwardly as the terminal is inserted into its respective bore in a connector body portion, and then snapping radially-outwardly in front of an annular surface in the body portion which will normally hold the terminal against rearward movement in the con10 nector under the rearwardly directed force imposed upon the terminal by the coupling thereof with a mating terminal, this annular body portion surface being inclined forwardly and radially-outwardly so that upon the application to the terminal of a rearwardly-directed ter15 minal-removal driving force greater than the coupling driving force, the retaining ring will be cammed radiallyinwardly against this body portion surface to permit withdrawal of the terminal from the body portion.

Another object of the present invention is to provide an 20 electrical connector of the character described wherein the forwardly-directed annular retaining face in each terminal-receiving bore of the connector body tapers forwardly and outwardly so as to provide a cam surface for constricting the retaining ring radially-inwardly to a 25 smaller diameter upon the application of a sufficient rearward force to the terminal for removal of the terminal from the body, and wherein the opposed, rearwardlyfacing surface of the terminal groove likewise tapers forwardly and radially-outwardly, but at a steeper angle 30 relative to the axis of the terminal and terminal bore than the retaining face and the bore, whereby the rearward removal force on the terminal will cause this tapered terminal groove surface to apply a radially-outwardly directed expanding force to the retaining ring which tends 35 to oppose the radially-inwardly directed camming force of the tapered bore surface, whereby the difference in the angles of taper relative to the axis between the said rearwardly-facing groove surface and forwardly-facing bore surface will provide an accurate control over the amount 40 of rearward force on the terminal which is required to remove the terminal from the bore. The tapers of said bore and groove surface, in addition to thus controlling the amount of removal or withdrawal force required on the terminal, also prevent damage to the ring, the terminal and the body portion of the connector by eliminating sharp engaging corners upon the application of the relatively heavy removal force to the terminal.

A further object of the present invention is to provide an electrical connector of the character described wherein ₆θ each terminal-receiving bore of the connector body portions is provided with a rearwardly and outwardly-flaring annular entrance ramp which is relatively gradual so as to constrict the retaining ring into the terminal groove, thereby permitting easy insertion of the terminals _gs into the terminal-receiving bores in the connector bodies; control of the slope of this annular entrance ramp and of the forwardly-facing side of the terminal groove which forces the retaining ring against the entrance ramp providing accurate control over the amount of insertion force 60 required.

It is thus a general object of the present invention to provide an electrical connector having contact elements or terminals which may be snapped into and out of their operative positions in the connector body portions, the _g5 terminals being retained in the connector bodies by retaining rings mounted in respective annular grooves on the terminals, wherein the angular relationship of the controlling surfaces on the terminals and in the terminalreceiving bores are such that the terminals can be readily inserted into the bores with a predetermined, relatively light insertion force, and the terminals can be withdrawn or pushed out of the bores with a predetermined, rela2,999,321 tively heavy removal force on the terminals, and wherein continued insertion and removal of the terminals will not cause any undue wear or damage, and removal can be accomplished by merely applying a removal or extraction force to individual terminals without requiring special tools or excessive clearances in a connector to accommodate such special tools.

Further objects and advantages of the present invention will appear during the course of the following part of this specification wherein the details of construction and the mode of operation of several preferred embodiments of the invention are described with reference to the accompanying drawing, in which:

FIG. 1 is an axial section of an electrical connector embodying the present invention and showing the two connector members thereof operatively interengaged;

FIG. 2 is a detail axial section on an enlarged scale, .illustrating a pin contact terminal operatively engaged in a terminal-receiving bore in one of the connector members;

FIG. 3 is a detail axial section on an enlarged scale illustrating a socket terminal operatively positioned in the other connector member;

·. FIG. 4 is a transverse section along the line 4—4 in FIG. 2;

FIG. 5 is a greatly enlarged detail axial section illustrating a portion of the structure shown in FIG, 2 so as to particularly illustrate the relationship of the surfaces in the terminal groove which receives the retaining ring and in the terminal-receiving bore, in a presently-preferred form of the invention;

FIG. 6 is a detail axial section similar to FIG. 2, but illustrating an alternative form of the invention embodying a molded-in contact retention sleeve; and

FIG. 7 is an axial section generally similar to FIG. 3, but illustrating an application of the present invention wherein the connector body includes a plurality of insulation block members.

Referring to the drawings, and at first particularly to FIG. 1 thereof, the present invention has been illustrated in connection with a connector 10 of generally conventional overall design. The connector 10 includes a receptacle connector member 12 and a plug connector mem' ber 14 which is receivable in the receptacle member 12. , The receptacle connector member 12 includes an openended tubular shell 16 having an outer flange 18 for mounting purposes, and having a forward skirt portion 20 /adapted to receive the plug connector member 14. The receptacle shell 16 is provided with an inside flange 22 disposed to the rear of the forward skirt portion 20, and •is also provided with an inside groove 24 disposed rearwardly of the flange 22. An insulation body 26 is mounted within shell 16, the body 26 having a forwardlyfacing shoulder 28 which engages against inside flange 22 so as to limit the insulation body 26 against forward .movement in the shell 16. The periphery of rear face 30 of insulation body 26 is engaged by a snap ring 32 which seats in groove 24 so as to hold the insulation body 26 against rearward movement in the shell 16.

A plurality of pin contact elements or terminals 34 are operatively positioned in respective axial bores 36 through insulation body 26, these pin contact elements or terminals 34 being removably-engaged in the respective axial bores 36 in the manner hereinafter described in detail. Although the connector 10 illustrated in the drawings has the pin contact terminals mounted in the receptacle member 12 and the socket contact terminals mounted in the plug connector member 14, it will be obvious to those skilled in the art that the socket terminals could be supported in the receptacle connector member and the pin terminals could be supported in the plug connector member, without in any way departing from the present invention.

A plurality of conductor wires 38 are both mechanically and electrically connected to the pin contact terminals 34 by engagement of the ends of conductors 38 in solder or crimping cups 40 at the rear ends of the contact terminals 34.

The receptacle shell 16 may be provided with an ex5 ternally-threaded rear portion 42 which is adapted to receive a conventional internal sealing grommet and an end bell, these parts being of conventional construction and therefore not being shown in the drawings.

The plug connector member 14 includes an open10 ended tubular shell 44 having an outer mounting flange 46, and having a forward skirt portion 48 adapted to fit within the skirt portion 20 of the receptacle connector member 12. A key 50 projects outwardly from the plug skirt portion 48 and is receivable in an axial slot 52 15 within the receptacle skirt portion 20 so as to provide correct alignment between the plug and receptacle connector members.

The plug shell 44 is provided with a rearwardly-facing inside surface 54 to the rear of the forward skirt portion 20 48, and is provided with an inside groove 56, spaced rearwardly from the surface 54. Insulation body 58 is disposed within the plug shell 44, and is positioned therein by engagement of the rearwardly-facing shell surface 54 against a forwardly-directed shoulder 60 on the insula25 tion body 58, and by engagement of the periphery of rear face 62 of the body 58 against a snap ring 64 which seats within the shell groove 56.

A plurality of socket contact elements or terminals 66 are removably-mounted within a plurality of respective 30 axial bores 68 through insulation body 58 in the manner hereinafter described in detail. A plurality of electrical conductors 70 are connected to solder or crimping cups 72 comprising the rear end portions of the respective socket terminals 66. The plug shell 44 is provided with 35 an externally-threaded rear portion 74 for receiving sealing grommet and bell members of conventional construction (not shown).

Referring now to FIGS. 2, 4 and 5, which illustrate in detail the principal features of the present invention, each 40 terminal 34 includes a generally-cylindrical body portion 75, with a pin contact portion 76 of reduced diameter extending forwardly thereof. The reduced pin portion 76 extends forwardly beyond the front face 77 of insulation body 26 so as to be exposed for engagement ₄₅ in a respective socket terminal 66.

Each terminal 34 is provided with an annular groove 78 in the cylindrical body portion 75 thereof for receiving a resilient retaining ring 80. The presently-preferred retaining ring 80 comprises a split metal ring having a sub50 stantial gap between the ends of the ring at the split, and may be composed of stainless steel, beryllium copper or other spring metal. It is to be understood, however, that the ring 80 may be composed of other resilient or spring materials having adequate structural strength, and in the 55 case of some plastic materials having the desired qualities of toughness, resiliency and memory, it may be desirable to employ a closed annular ring rather than a split ring.

In its relaxed or unstressed condition, the retaining ring ₆₀ 80 is of such a size that it will extend partly inside of and partly outside of the annular groove 78; i.e., the inside diameter of the ring will be substantially less than the diameter of the cylindrical body portion 75 of terminal 34, and the outer diameter of the ring 80 will be sub55 stantially greater than the diameter of the cylindrical body portion 75. Prior to engagement of the terminal 34 in the body of the connector, the ring 80 is mounted on the terminal in the groove 78 by merely sliding the ring 80 over the pin portion 76 of terminal 34 and then expandγθ ing the ring over the forward part of the cylindrical body portion 75 and in to the groove 78.

The rear side of groove 78 is defined by forwardlydirected face 82 which is preferably planar and disposed at right angles to the axis of the terminal so as to provide 75 a positive abutting face against which the ring 80 will moral force, the relationship between the angles efinciine $W,S21 'g

Seat as the terminal is pushed into bore 36 from the rear of insulation body 26. Some rearwardly and outwardlydirected taper could be employed in the forwardly-directed groove face 82, if desired, but insertion of the terminal in the terminal-receiving bore is facilitated by having this 5 face 82 steep relative to the axis of the terminal, and preferably at substantially right angles thereto.

The front side of the groove 78 is defined by rearwardlydirected face 84 which inclines forwardly and radiallyoutwardly from the bottom of groove 78 so as to face in io a rearward, radially-outward direction, the purpose of this incline of the face 84 being explained in detail hereinafter.

The terminal 34 is also provided with an external flange 86 which is positioned substantially to the rear of groove 78 and which serves to limit the forward travel of the terminal in the bore 36.

The bore 36 is provided with a forwardly and radiallyinwardly directed face or shoulder 88 which inclines forwardly and radially-outwardly from the most constricted portion 89 of bore 36 to a forward counterbore 90 extending forwardly to the front face 77 of insulation body 26.

By inclining the forwardly-directed bore face or shoulder 88 so that it extends forwardly and radially-outwardly from the most constricted portion 89 of the bore, tliis forwardly-directed face 88 provides a cam surface against which the retaining ring 80 is compressed radially-inwardly within the terminal groove 78 when the terminal is pulled or pushed rearwardly, so that the ring 80 will be reduced in diameter to a size permitting the ring to pass rearwardly through the constricted portion 89 of the bore 36, allowing complete rearward extraction of the terminal 34 from the body of the connector. If the forwardlydirected bore face 88 were at right angles to the axis, it would permanently lock the terminal in its seated position within the body, and attempts to remove the terminal by merely pushing or pulling it rearwardly would tend to shear and damage the ring, and also would damage the holding face in the bore, and the opposed portion of the terminal.

Although the amount of incline of the bore face 88 relative to the axis of the bore is not in any way critical, it has been found in one example of the invention that an angle of incline of approximately 45 degrees relative to the axis provides excellent results.

The forwardly and radially-outwardly directed incline of the rearwardly-facing face 84 in the terminal groove 78 serves several important functions. First, by controlling the steepness of the incline of groove face 84 relative to the incline of bore face 88, the amount of force required to withdraw the terminal from the body may be accurately controlled. This is for the reason that while the forwardly-directed bore face 88 tends to cam the ring 80 radially-inwardly, the rearwardly-directed opposing face 84 of the terminal tends to cam the ring radially-outwardly. By having the angle of incline of the terminal face 84 greater relative to the axis than the angle of the bore face 88, the cam atcion of the bore face 88 will be greater than the cam action of the terminal face 84, with the net result that the ring §0 will be cammed inwardly to permit removal of the terminal from the connector body. The amount of removal force required will depend upon just how much steeper the angle of incline of the terminal face 84 is as compared with the angle of incline of the bore face 88, relative to the axis. Thus, it is the difference between the angles of incline relative to the axis of the terminal face 84 and the bore face 88 which controls the amount of removal force required. In the embodiment of the invention shown in FIGS. 2 and 5, the angle of incline of the groove face 84 relative to the axis is about 60 degrees, which provides a differential angle of about 15 degrees between the grooved surface 84 and the bore surface 88.

1.. For a particular pre-selected amount of terminal reof the terminal groove face 84 and the bore face 88 will be controlled in part according to the size and composition of the ring 80. The amount of removal force for which the surfaces 84 and 88 are set will depend upon the size and usage of the connector, and also upon the number of terminals in the connector. Thus, where the pin and socket contacts of the connector members are coupled together with a relatively heavy frictional connection, it is desirable to have the surfaces 84 and 88 set at a relatively small differential angle so as to require a relatively heavy force for removing each individual terminal. In this manner, the terminals are not likely to become accidentally dislodged upon interengagement of the con15 nector portions. However, where the pin and socket terminals are coupled together with a relatively light frictional engaging force, which is usually the case where a large number of terminals are employed in the connector, then a larger differential angle may be provided be20 tween the surfaces 84.and 88 to permit easier removal of the individual terminals when desired, without possibility of accidental dislodging of the terminals when the connector portions are engaged.

Rearwardly of the annular entrance ramp 92, the 25 bore 36 is provided with a rearwardly-facing annular surface 94, a rear counterbore 96 extending rearwardly from surface 94 to the rear face 36 of the insulation body 26. The flange 86 on terminal 34 abutts against this rearwardly-facing surface 94 of the insulation body 26 30 so as to limit forward travel of the terminal in the bore beyond the position shown in FIGS. 2 and 5, wherein the terminal groove 73 is proximate the surface 88 in the body.

The contacts 34 may be removed from bore 36 by 35 impact on a mating contact, or by a straight push or pull on the contact. It will be apparent that no special tools are required, and that therefore, no undesirable, space-consuming excessive clearances are required in the forward part of the insulation body around the terminal 40 to permit insertion of such a tool for collapsing the retaining ring. Accordingly, all portions of the bores 36 may be relatively small in diameter, and a maximum number of terminals may be provided in a connector of a given cross-sectional size.

FIG. 3 of the drawings illustrates the present invention as applied to one of the socket terminals 66 in the insulation body 58 of plug connector member 14. The socket terminal may have a forward socket portion of any desired type, the socket portion 98 of the illustrated 50 terminal 66 being of the type which has an external portion of reduced diameter about which is disposed a spring-gripping member 162, a portion of which extends through the wall of the socket terminal so as to resfliently engage a respective pin contact element. Socket ter55 rninals of this general type are shown and described in co-pending application, Serial No. 744,947, “Socket Terminals for Electrical Connectors,” filed June 27, 1958. The forward end of socket terminal 66 is preferably recessed slightly inside of, or to the rear of the forward face

104 of insulation body 58.

It will be apparent from FIG. 3 of the drawings that the application of the present invention to a socket terminal is identical to the application to a pin terminal. Thus, the retaining ring 86α is disposed within annular 65 terminal groove 78α which is defined between a forwardlydirected face 92a preferably disposed at approximately right angles to the axis of the terminal, and a rearwardly and radially-outwardly facing face 84α which extends from the bottom of the groove forwardly and radially70 outwardly at an incline relative to the axis of the terminal, this annular groove 78α being disposed in a generally cylindrical body portion 75α of the terminal.

As the socket terminal 66 is inserted into the insulation body 58 through the rear face 62 thereof, the ring

80α is cammed radially-inwardly by the gradually slop2,000,221 groove 144. The groove faces 146 and 148 correspond; respectively, to the faces 82 and 84 of the embodiment shown in FIGS. 2 and 5.

Contact retaining ring 150 is disposed in the groove 144, 5 and in its unstressed condition, a portion of the ring 150 lies within the groove 144, while a portion of the ring 150 extends radially-outwardly beyond the cylindrical surface of the terminal.

The rear insulation block 134 is provided with axial 10 bore 152 which has a gradual flare in its rear end to provide annular entrance ramp 154, and is provided with a short, relatively steep, front flare 156 which terminates at the interface 136. The flare 156 corresponds in incline, and in function, with the forwardly and inwardly-directed 15 surface 88 in the insulation body 26, as best shown in FIGS. 2 and 5 of the drawings.

The front insulation block 132 is provided with an axial bore 158 which is aligned with the bore 152 of rear insulation block 134. The bore 158 extends rearwardly to the 20 interface 136 at a diameter which is preferably approximately the same as the diameter of the outermost portion of the front flare 156 in the bore 152 of the rear block 134'. The front insulation block 132 is provided adjacent its front face with a radially-inwardly directed flange 160 25 which serves as an abutment limiting the extent of forward travel of the terminal 138 in the insulation body» It is preferred to provide a forward flare 162 in flange 160 as a guide for a pin contact element which is being moved into coupling engagement with the socket contact terminal 30 138.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of 35 the invention, which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims.