US3173740A

US3173740A - Self-locking electrical plug connector

Info

Publication number: US3173740A
Application number: US322746A
Authority: US
Inventors: Robert E Barnes
Original assignee: AUTO SWAGE PRODUCTS Inc
Current assignee: AUTO SWAGE PRODUCTS Inc
Priority date: 1963-11-12
Filing date: 1963-11-12
Publication date: 1965-03-16
Anticipated expiration: 1982-03-16

Description

March 16, 1965 R. E. BARNES SELF-LOCKING ELECTRICAL PLUG CONNECTOR Filed Nov. 12 1963 m r 2 I I m a M I I I 0 1 I m E M I n I m u 5.0" Ill 1/ Wm C w a P HII'ORNEYS.

United States Patent Ofiice 3,173,74t) SELF-LOCKING ELECTRICAL PLUG CONNECTGR Robert E. Barnes, Trumbull, Comm, assignor to Auto- Swage Products, Inc, Shelton, COHIL, a corporation of Connecticut Filed Nov. 12, 1963, Ser. No. 322,746 8 Claims. (Cl. 339-4217) This invention relates generally to self-locking electrical plug connectors, and more particularly, to selflocking electrical plug connectors which are adapted for use in the plugboard of a circuit connecting panel of an electrical calculating or accounting machine or the like.

Prior art connectors of the foregoing type are usually of complex design, generally including multiple intricate parts which are dillicult and expensive to manufacture and assemble into the connector, or if made of a less expensive construction, are unreliable or defective in operation.

It is an object of the invention to provide an improved, reliable, inexpensive self-locking electrical plug connector of the type which may be withdrawn from a plugboard by pulling the electrical connector or the electrical conductor wire to which the connector is attached, but which may not normally be pushed from the plugboard by pressure on the nose of the connector.

It is a further object of this invention to provide a connector as set forth in the preceding paragraph having an improved spring detent locking system, particularly one that requires greater force to pull out the connector than it does to push it into the plugboard.

It is a still further object of the invention to provide a self-locking electrical plug connector which is simple and economical in construction and assembly, not subject to malfunction or accidental disassembly during use or handling, rugged and foolproof in Operation, and has a long life expectancy.

Other objects and advantages of the present invention will become apparent to those skilled in the art upon a consideration of the following detailed description taken in conjunction with the drawings, wherein:

FIG. 1 is a perspective view of a self-locking electrical plug connector embodying my invention, with a con ductor wire attached;

FIG, 2 is a perspective view of the elements of the spring detent locking system of the FIG. 1 embodiment;

FIG. 3 is a vertical sectional view taken through the FIG. l'connector shown in fully mounted position in a plugboard, with some associated parts;

FIG. 4 is a view similar to H6. 3, but showing the connector partially withdrawn from the plugboard, and

FIG. 5 is a sectional view taken substantially on line 55 of FIG. 4.

With reference to the drawings, and particularly FIGS. 1 and 2, my improved self-locking electrical plug connector is indicated generally by reference character C, and it comprises three elements: connector body 10, cam pin 22, and ball detent spring member 28.

Connector body 19 is elongated, generally cylindrical and hollow, and includes a tapered annular wall por tion ll, a forward reduced diameter sleeve portion 12 having a passage 13, an intermediate raised annular rib 14, and a rear portion 16 adapted to be secured about an end of a conductor wire W which is attached to the connector C. Rear body portion 16 may be rigidly secured to the conductor wire W in any convenient manner, as by crimping, so as to effect both good elec trical and mechanical connection, and if desired piercing members 18, as can be seen in FIG. 3, may be provided on the portion 16 to pierce the conductor wire W to efiect good electrical connection. At one peripheral portion of the body 19 adjacent tapered wall portion 11, a circular detent opening 20 is formed through the Wall of the body. The connector body ill may be formed in any convenient manner; however, in practice it has been ettectively and economically formed by swaging flat stock into its completed form illustrated. Whenformed in this manner, an axial slit seam exists which is of no operational significance. Alternatively, the connector body could be formed of tubular stock to desired shape. In the latter event, if desired, a slit 17 may be provided to facilitate crimping of rear portion 15 about the wire W; however, this is an optional feature and of no operational significance.

Cam pin 22 comprises an elongated rod-like pin portion 24 having at one of its ends an enlarged cam head 26 in the form of a truncated conical enlargement with a narrow cylindrical surface 27. Cam pin 22 may conveniently be formed on a screw machine.

Ball detent spring member 28 comprises an integral elongated rod-like round wire member which, as may be conveniently done on a wire forming machine, is bent into a U-shaped spring portion 30, and has an enlarged spherical ball detent portion 32 formed, as by swaging, at one of its ends. The other end 33 of the spring portion 36 is formed to include a fiat side 34, the opposite side of which is rounded, as can be seen in FIG. 5, to generally conform to the inner surface of body 16. The ball detent spring member 28 when in its free state has the legs of the U-shaped spring portion 39 diverged substantially more than when they are in their fully mounted position shown in FIGS. 3 and 4, and therefore, it must be stressed to be mounted in the connector body N.

T o assemble the spring de-tent system comprising the cam pin 22 and ball detent spring member 28 within the connector body 10, with reference to FIG. 3 for purposes of convenience, the cam pin is first inserted into the connector body, formed as illustrated, axially from the right hand side, pin portion 24 first, until it slides into the passage 13 formed in the reduced portion 12 of the connector body. The dimensional relationship between the cam pin 22 and the passage 13 is such as to permit a nice sliding fit of the pin portion 24, but retention of the cam pin within the connector body as a result of cam head 26-tapered wall portion 11 engagement. The ball detent spring member 28 is then inserted into the connector body axially from the right by being preliminarily stressed so as to be able to clear the internal walls of the connector body, the manipulation being somewhat in the nature of squeezing the open ends of a hairpin. The open end of the member 28 is inserted first with the ball detent portion 32 oriented to be aligned with detent opening 20 and the member 28 moved axially into the body 10 until the ball detent portion is disposed with in the detent opening 20, as shown FIGS. 3 and 4. On reaching this position, the ball detent portion snaps into the detent opening, as a result of the release of the stored energy in member 28, and is firmly biased radially outwardly in the opening. With reference to FIG. 3 it will be observed that at this time the end 33 of member 28 contacts tapered wall portion 11, a substantial part of cam head 26 of the cam pin 22 is disposed between the ball detent portion 32 and the flat side 34 of the member 28, and that the narrow cylindrical surface 27 of the cam head is in contact with the fiat side. The contact of end 33 with tapered wall portion 11 restrains the member 28 axially in the forward direction (toward the left in FIG. 3). However, the end 33 of member 28 is axial- 1y unrestrained in the rearward direction (toward the right in FIG. 3), and therefore, the member 28 is float- Patented Mar. 16, 1965 'this is operationally desirable.

I ingly mounted. This dispositional arrangement effects a certain amount of stability of the parts, as by preventing jamming of the cam pin 22 in passage 13 in operation, and juxtaposes the cam head 26 relative to the ball detent portion 32 and the flat side 34 so as to be poised for subsequent operation in a desired manner. It should be noted that in the FIG. 3 condition of the connector, the cam head 26 is spaced to the right of the tapered wall portion 11 of the connector body 19, and therefore, the cam pin 22, under certain operational circumstances, is free to move axially to the left relative to the body 10.

Assuming the connector C is fully assembled as shown in FIG. 3, if it is desired to insert it into an aperture of a movable plugboard P, it is inserted therein nose first. During the step of insertion, the ball detent portion 32, which normally extends beyond the periphery of the connector body 10, will be engaged by the adjacent wall portion of the plugboard surrounding the aperture 0 and be forced to retract radially inwardly to permit it to clear through the aperture. This retraction is allowed by combined operation of the cam pin 22 and the ball detent spring member 28. The cam pin 22 is carnmed axially forwardly relatively to the connector body during this operation to its dotted line position of FIG. 3 and its solid line position of FIG. 4 as a reaction to the radial retraction of ball detent portion 32 interacting with cam head 26. The member 28 is floatingly mounted and slides axially to the right relative to the connector body 10 in reaction to force exerted on the ball detent portion 32 by the edge of aperture 0 during insertion. During this movement of member 28, an edge of opening in the connector body (the right edge with reference to FIG. 3) engages the ball detent portion 32 and exerts a retracting force on it. The combined effect of the retracting forces produced by the aperture 0 and opening 20 on ball detent portion 32 is to permit the connector C to be inserted relatively easily, which is operationally desirable. After the connector is inserted sufliciently into aperture 0, it will reach the position shown in FIG. 3 wherein the ball detent portion 32 will spring radially outwardly through the detent opening 20 beyond the periphery of the connector body 10 into a locking position and engage the adjacent edge of the plugboard aperture 0. In this position, the free end of the pin portion 24 of the cam pin 22 will have engaged the stationary contact C, which may take any convenient known form,.and this will cause the cam pin 22 to axially retract into the connector body 10 to the solid line position of FIG. 3. In this condition, the end 33 contacts tapered wall portion 11 and the connector is mounted and locked in the plugboard P in electrical engagement with the stationary contact. Any force or pressure exerted on the head of the connector, that is, the portion thereof in the vicinity of the free end of the pin portion 24 of the cam pin or reduced portion 12 of the connector body, is incapable of pushing the connector out of the plugboard aperture 0.

The effect of such a force, if exerted, on the cam pin 22 is to cam the ball detent portion 32 radially outwardly, asa result of the interrelation of the conical portion of cam head 26 with the spherical ball detent portion. This urges the ball detent portion radially outwardly into tighter engagement with the adjacent edge of the plugboard aperture 0. Therefore, it is not possible to remove the connector from the plugboard P by a force exerted on the head of the connector, short of a destructive blow.

If it is desired to remove the connector C from the plugboard aperture 0, a pull on the conducter wire W or the rear portion 16 of the connector body 10 will effect such removal; however, it requires a substantial pull to do so. My improved connector is designed to require greater force to remove it than is required to insert it, and

With the connector elements disposed as in FIG. 3, a pull toward the right on the wire W will result in the ball detent portion 32 being forced radially inwardly, ultimately to its position shown in FIG. 4, as a result of its engagement with the adjacent edge of the plugboard aperture 0. However, there is no axial movement of the member 28 relative to the connector body because end 33 of the member is in contact with tapered wall portion 11 and prevents the member from sliding to the left relative to the connector body. Therefore, the connector body does not exert a retracting force on the ball detent portion 32 when the connector is pulled out of the panelboard. Such radial retraction of the ball detent portion 32 is permitted when the wire W is pulled because the cam pin 22 is cammed axially toward the left as viewed in FIG. 3 during such operation to its dotted line position. The axial displacement of cam pin 22 to the left relative to connector body It) creates space for the ball detent portion 32 to retract radially inwardly of the body. FIG. 4 illustrates the condition of the elements as a connector is being pulled out of the plugboard aperture 0. It requires greater force to pull the connector out of the aperture 0 than is re quired to insert it, because on insertion, due to the mounting of ball detent spring member 28, there are greater retractive forces acting on the ball detent portion 32 than on withdrawal.

It should be observed that my improved connector comprises essentially three elements: a connector body 16, a cam pin 22 and a ball detent spring member 28, all of which may be readily and economically formed. These elements lend themselvesto economical mass production and assembly of the connector is easy and inexpensive. After assembly, my economical connector functions better than any known connectors of the type involved which even approach the simplicity of my connector. It is extremely important to note that reliable operation and long life is produced by my connector largely because of the spherical operating surfaces of the ball detent portion of the ball detent spring member. Low cost connectors are known Where detent spring members are formed by stamping them out of sheet stock. These spring members have sharp edges and burrs on their detent portions, and these dig into the plugboard around the mounting apertures and stick in and/ or damage the plugboard. My spherical ball detent portion slides smoothly over the plugboard. I am aware of some connectors that employ ball detents; however, they are very expensive and require complex intricate elements, such as ball supports. By combining the spherical ball detent portion and the spring portion into single member 28, I have provided an economical and effective spring detent system.

As will be evident from the foregoing descriptions, certain aspects of my invention are not limited to the particular details of construction of the example illustrated, and I contemplate that various and other modifications and applications will occur to those skilled in the art. It is, therefore, my intention that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A self-locking electrical plug connector for selective insertion into and removal from an aperture in a plugboard comprising: an elongated hollow body adapted to be secured at one of its ends to a conductor wire and to be selectively disposed to have its other end extend through the plugboard aperture; means for retaining said body in the plugboard aperture comprising an opening in a side of said body, a retractably mounted detent arranged in said body to extend partially through said opening to the exterior thereof to a locking position, and biasing means arranged to bias said detent partially through said opening to its locking position; said detent and said biasing means being formed by an integral U-shaped spring member having said detent formed at one of its ends and its other end in contact with an inner surface of said body, said member mounted so as normally to be longitudinally unrestrained in one direction so as to be movable relative to said body toward said one end of said body on insertion and restrained in the other longitudinal direction so as not to be movable relative to said body toward said other end of said body on removal, whereby insertion of the connector is more readily effected than its removal; said detent being retractable in response to insertion of said connector into or pulling of said connector out of the plugboard aperture; and means for preventing removal of said connector out of the plugboard aperture by a force applied to said other end of said body comprising a cam pin movably mounted in said body and having a pin portion extending through and projecting beyond said other end and an enlarged cam head portion disposed within said body adjacent said detent and arranged to engage and force said detent in a direction out through said opening to the locking position in response to a force applied to said pin portion, said detent being spherical over all operating surfaces thereof which engage the rim of said opening or the edges of the plugboard aperture at any time in operation.

2. A connector as defined in claim 1 wherein a substantial part of said cam head portion is disposed between the ends of said spring member.

3. A connector as defined in claim 2 wherein the end of said spring member that contacts said body has a side in contact with said cam head portion which functions to position and guide said cam pin.

4. A connector as defined in claim 1 wherein said member is formed of bent Wire and said detent is an enlargement formed at one end of the wire.

5. A connector as defined in claim 1 wherein said other end of said body is of reduced size relative to the remainder of said body and includes a passage; said cam pin portion is slidably mounted in said passage; and said cam head portion is larger than said passage.

6. A self-locking electrical plug connector for selective insertion into and removal from an aperture in a plugboard comprising: an elongated hollow cylindrical body adapted to have one of its axial ends secured to a condoctor Wire; the other axial end of said body being reduced, cylindrical, and having a passage connecting the exterior with the interior of said body; a cam pin comprising a cam head disposed within the interior of said body and a pin portion extending through said passage to project to the exterior of said body; an integral detent spring wire member comprising a bent generally U-shaped spring wire portion having a spherical enlargement detent portion formed at one end; a radial opening formed in a side of said body; said member disposed Within said body with said detent portion normally disposed within and partially extending through said opening to the exterior of said body to a locking position, and the other spring portion end disposed within and arranged to contact said body and place said spring portion under compression to bias said detent radially outwardly; said other spring portion end being axially unrestrained in one direction so as normally to be axially movable relative to said body toward said one end of said body on insertion and restrained in the other axial direction so as not to be axially movable relative to said body toward said other end of said body on removal; and said cam head disposed contiguous with raven said detent portion, whereby said detent portion may retract radially inwardly only if said cam pin is free to slide axially out said reduced end and insertion of the connector is more readily effected than its removal.

7. A connector as defined in claim 6 wherein a substantial part of said cam head is disposed between the ends of said spring portion; and said other spring portion end has a fiat side in contact with said cam head to position and guide it.

8. A self-locking electrical plug connector for selective insertion into and removal from an aperture in a plugboard comprising: an elongated hollow body adapted to be secured at one of its ends to a conductor wire and to be selectively disposed to have its other end extend through the plugboard aperture; means for retaining said body in the plugboard aperture comprising an opening in a side of said body, a retractably mounted detent arranged in said body to extend partially through said opening to the exterior thereof to a locking position, and biasing means arranged to bias said detent partially through said opening to its locking position; said detent being retractable in response to insertion of said connector into or pulling of said connector out of the plugboard aperture; means for preventing removal of said connector out of the plugboard aperture by a force applied to said other end of said body comprising a cam pin movably mounted in said body and having a pin portion extending through and projecting beyond said other end and an enlarged cam head portion disposed within said body adjacent said detent and arranged to engage and force said detent in a direction out through said opening to the locking position in response to a force applied to said pin portion; said detent being spherical over all operating surfaces thereof which engage the rim of said opening or the edges of the plugboard aperture at any time in operation; and means permitting said detent to move in said opening relatively toward said one end of said body on insertion and preventing said detent from moving in said opening relatively toward said other end of said body on removal, whereby insertion of the connector is more readily effective than its removal.

References tilted by the Examiner UNITED STATES PATENTS 1,010,432 12/11 Jones 292l7 1,025,157 5/12 Prahar 292-17 2,256,243 9/41 Edwards -5 2,331,851 10/43 Spooncr 855 2,779,929 1/57 Sesny et a1 339217 2,787,771 4/57 Francis 339-217 X 2,903,670 9/59 Sitz 339217 X 2,983,978 5/61 Wilgus 85-5 X 3,088,118 10/61 Mavity 339-217 3,085,222 4/63 Watts 339-217 3,134,633 5/64 Hatfield 339-217 OTHER REFERENCES Twin Detent Patchcords by AMP, Arnp Incorporated, Harrisburg, Pa, copyright 1962.

JOSE-PH D. SEERS, Primary Examiner. ALBERT H. KAMPE, Examiner.

Claims

6. A SELF-LOCKING ELECTRICAL PLUG CONNECTOR FOR SELECTIVE INSERTION INTO AND REMOVAL FROM AN APERTURE IN A PLUGBOARD COMPRISING: AN ELONGATED HOLLOW CYLINDRICAL BODY ADAPTED TO HAVE ONE OF ITS AXIAL ENDS SECURED TO A CONDUCTOR WIRE; THE OTHER AXIAL END OF SAID BODY BEING REDUCED, CYLINDRICAL, AND HAVING A PASSAGE CONNECTING THE EXTERIOR WITH THE INTERIOR OF SAID BODY; A CAM PIN COMPRISING A CAM HEAD DISPOSED WITHIN THE INTERIOR OF SAID BODY AND A PIN PORTION EXTENDING THROUGH SAID PASSAGE TO PROJECT TO THE EXTERIOR OF SAID BODY; AN INTEGRAL DETENT SPRING WIRE MEMBER COMPRISING A BENT GENERALLY U-SHAPED SPRING WIRE PORTION HAVING A SPHERICAL ENLARGEMENT DETENT PORTION FORMED AT ONE END; A RADIAL OPENING FORMED IN A SIDE OF SAID BODY; SAID MEMBER DISPOSED WITHIN SAID BODY WITH SAID DETENT PORTION NORMALLY DISPOSED WITHIN AND PARTIALLY EXTENDING THROUGH SAID OPENING TO THE EXTERIOR OF SAID BODY TO A LOCKING POSITION, AND THE OTHER SPRING PORTION END DISPOSED WITHIN AND ARRANGED TO CONTACT SAID BODY AND PLACE SAID SPRING PORTION UNDER COMPRESSION TO BIAS SAID DETENT RADIALLY OUTWARDLY; SAID OTHER SPRING PORTION END BEING AXIALLY UNRESTRAINED IN ONE DIRECTION SO AS NORMALLY TO BE AXIALLY MOVABLE RELATIVE TO SAID BODY TOWARD SAID ONE END OF SAID BODY ON INSERTION AND RESTRAINED IN THE OTHER AXIAL DIRECTION SO AS NOT TO BE AXIALLY MOVABLE RELATIVE TO SAID BODY TOWARD SAID OTHER END OF SAID BODY ON REMOVAL; AND SAID CAM HEAD DISPOSED CONTIGUOUS WITH SAID DETENT PORTION, WHEREBY SAID DETENT PORTION MAY RETRACT RADIALLY INWARDLY ONLY IF SAID CAM PIN IS FREE TO SLIDE AXIALLY OUT SAID REDUCED END AND INSERTION OF THE CONNECTOR IS MORE READILY EFFECTED THAN ITS REMOVAL.