US3663924A

US3663924A - Safety outlet

Info

Publication number: US3663924A
Application number: US111043A
Authority: US
Inventors: Matthew E Gerlat
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-01-29
Filing date: 1971-01-29
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16

Abstract

The device disclosed is an outlet which may be connected to a standard rubber insulated lamp cord without stripping the insulation and may be positioned at any point along the length of the cord. The cord piercing contacts are arranged to move with a clamp member which provides strain relief and which is so formed as to block the use of the outlet before the strain relief and the contacts are engaged and is further shaped to prevent the strain relief and the cord piercing contacts from being disengaged while a plug occupies the outlet.

Description

Patented May 16, 1972 3,663,924

2 Sheets-Sheet 1 SAFETY OUTLET There are a number of other devices for attaching outlets along electrical conductors but in the known examples of such devices special electrical conductors are required in specific shapes to accommodate the clamping mechanism. I know of the following:

Abramson 3, l 48,009 9/8/64 Messing 2,942,224 6/21/60 Platz et al. 2,946,037 7/19/60 Smith 2,682,647 6/29/54 Carlson 2,856,592 /14/58 De Mask 1,805,572 5/19/31 SUMMARY OF THE INVENTION So far asl am'aware, none of the previous devices are capable of connections anywhere along a standard electrical cord using piercing contacts which do not require stripping of the cord and in which the openings for the prongs of a plug are so covered that they are open only when the contacts are fully engaged with the conductors of the cord and the strain relief is also in position, the structure being such that the safety features cannot be defeated. These objects are accomplished by providing an outlet body with a cord channel extending through it at one side. A strain relief shaft is rotatable in the body and is provided with helical thread or cam members engagable with the body to cause it to move axially when it is rotated. The end of the shaft is so formed as to engage a cord in the channel with great force but without damage to the insulation of the cord. Preferably, it has a round conical point. An optional recess may be provided in the cord channel opposite the point so that the cord is bent as it is clamped. This optional feature provides extremely secure strain relief but has been found not essential because the clamping force is very great without such a recess. A pair of slidable contacts may enter the strain relief shaft and are provided with sharpened points. In the embodiment shown in which the cord is a two conductor cord, these points are disposed at opposite sides of the cord channel to engage the respective conductors of the conventional flat lamp cord. Each contact is provided with a flange struck from the material of the contact which is received in an annular channel or groove in the strain relief shaft so that the contact is carried along with the shaft and is bent to extend along the side of the channel for the prongs. The head of the strain relief shaft is enlarged to cover the openings for the prongs of a plug and relieved to provide openings when turned to strain relief position. Because the cover for the prong openings is an integral part of the strain relief clamp and of the mechanism which advances the contacts to pierce the conductors of an electrical cord, no connection can be made to the outlet until it is secured in a safe position on the electrical cord with the prongs engaged with the conductors. By the same token, the prongs of a plug when inserted into the openings provided in order to make electrical contact, become a lock which prevents movement of the strain relief shaft and thereby prevent accidental loosening of the strain relief or disengagement of the outlet contacts from the electrical cord. Thus, a number of safety features are present. Engagement of the electrical contacts of the outlet with a cord is simultaneous with the provision of strain relief preventing damage to the contacts and to the cord, and the outlet is unusable except when strain relief and electrical Contact cannot be broken. Also the parts required are few and simple.

Preferably the outlet may be loose on a cord having a fixed plug and fixed outlet at the ends, to prevent overloading the cord.

DRAWINGS ln the drawings,

FIG. l is a perspective view of a cord set having the safety outlet of my invention applied as a second outlet between the ends ofthe cord set.

FIG. 2 is a view showing the body of the safety outlet of my invention opened at its midline.

FIG. 3 i s` an exploded view showing the clamping shaft and the electrical contacts of-my safety outlet.

FIG. 4 is a top view of the safety outlet of my invention showing the plug prong openings exposed.

FIG. 5 is a top view of the safety outlet of my invention showing the plug prong openings covered.

FIG. 6 is aview like that of FIG. 2 showing the optional recess in the cord channel to enhance the effectiveness of the strain relief.

FIG. 7 is like FIG. 6 except that it shows the strain relief shaft rotated 90 to withdraw the contact from the electrical cord and block the plug prong openings so that the outlet is free to move to a new position along the electric cord. FIG. 8 is a cross-sectional view on line 8 8 of FIG. 2.

DESCRIPTION It will be noted that the structure shown has only three kinds of major parts. The two body shells required are identical; the two contacts required are identical; and a single strain relief shaft is required. The parts are also exceedingly easy to manufacture and to assemble. The body halves may advantageously be molded from plastic, as may the strain relief shaft. The contacts are readily constructed on standard machinery from a single piece of metal each. There is little waste if a strip of metal the width of the contact is used. All that is required for assembly is to place two of the contacts on either side of the strain relief shaft in half of the body shell. The other half ofthe body shell is placed on top and a pair of rivets are placed in the two holes at the sides. This exceptionally simple and economical structure is in marked contrast to other devices of the kind shown in the prior art of which I am aware. In addition, it presents a combination of safety features not present in prior art of which I am aware.

The description and drawings herein are illustrative of the specific embodiments shown and are not intended to limit the invention, which is defined by the appended claims.

As shown in the drawings, my safety outlet consists of a pair of identical body parts 10, a pair of identical contacts 30, and a strain relief member 40.

The body parts 10 are preferably provided with a pair of openings l1, one on each side, to receive a pair of suitable fastenings such as rivets 12. A channel 13 is provided to receive an insulated electrical conduct 14, shown here as a standard, twoconductor lamp cord.

In the embodiments shown in FIG. 2, cord channel 13 is straight, while in the embodiments shown in FIGS. 6 and 7 channel 13 has a depression 15 into which the strain relief member 40 presses cord 14. Body 10 is also provided with channel 16 to receive strain relief member 40 and contacts 30 for axial movement into and out of channel l5. Channel 16 is interrupted to provide an opening through which contacts 30 extend from strain relief member channel 16 into plug prong channels 17. The upper part of body 10 is relieved sufficiently at 18, at the upper end of the respective plug prong channels 17 to make clearance to receive the circular head 4l of the strain member 40. Finally, each body member l0 is provided with a protuberence 19 (seen only in FIG. 8) which serves as a fixed reaction member against which strain relief member 40 pushes while it is moving axially or applying pressure to cord 14.

Electrical contacts 30 are generally U-shaped, having a shorter end 31 which serves to make contact with another electrical device such as the prong of a plug similar to plug 14C. As shown in the drawings, end 3l of contact 30 extends into channel 17 of body 10 at a slight angle so that upon insertion of the prong 14e of a plug similar to plug 14C, Contact end 31 will make electrical contact with it. End 3l is connected by a bend 32 with a longer leg 33. Bend 32 is located near head 4l of strain relief member 40 within channel 16 of body 10. Leg 33 is provided with a flange 34 which is preferably struck a plurality of contacts each having a pointed end adapted to move axially to and from engagement with a respective conductor with said clamp means as said clamp means is rotated, openings in said body adapted to receive the prongs of an electrical plug, and means attached to said clamp means to block said prong openings until said clamp means and said points are moved axially into said cord channel. 9. The device of claim 8 in which said body is provided with an integral protuberance,

said clamp means comprising a shaft provided with a helical screw thread engaging said protuberance, said openings for said plug contacts comprising a pair of parallel channels extending at right angles to said cord channel, said outlet contacts being U-shaped and having a short end portion of the U extending along the side of the respective plug openings and a long leg portion of the U extending alongside the shaft of the clamp means, said shaft being provided with a circumferential groove and said outlet contact being provided with flanges entering said groove. 10. For making strain relieved contacts with an insulated electrical conductor, a body having a channel to receive said insulated conductor, an electrical contact having a point adapted for axial movement toward and into the channel and through the insulation to make electrical contact with said conductor,

a strain relief member adapted to move axially into contact with the insulation of said conductor to apply pressure thereto against the wall of said channel,

an opening in said body providing access to said contact member for making an electrical connection thereto, and

means operated by said strain relief member preventing access to said last mentioned opening when said strain relief member is not in a position in which pressure is applied to said electrical insulation, and having an opening permitting such access when said member is in pressure applying position.

ll. The device of claim 10 in which the contact and the strain relief member are connected for simultaneous axial movement into said channel.

12. The device of claim 10 in which the means preventing access to said opening for making electrical contacts is also adapted to lock said strain relief member in its pressure applying position when an electrical conductor extends through said opening for connection to said contact.

* it lk nited vStates Patent Proctor [451 May 16, 1972 [54] ELECTRICAL CONNECTOR FOREIGN PATENTS 0R APPLICATIONS [72] Inventor; Richard D J. Proctor, Portsmouth, R 1 1,232,014 4/ 1960 France ..339/17 LC [73] Assignee: The United States of America as represented by the Secretary of the Navy Primary Examiner-Joseph H. McGlynn Attorney-R. S. Sciascia and Henry Hansen l 5 7 l ABSTRACT An* electrical connector for interfacing a PC (printed circuit) board with external circuits. A nonconductive core, formed to engage the edgeof the PC board adjacent to the printed circuit terminals, receives two rows of opposed contact springs, each Spring having a bifurcated portion in the core for receiving a contact pin of an external circuit and a base portion extending outwardly for engaging either side of the circuit board at selected terminals. The bifurcated portions of each spring are inwardly inclined from their respective ends to form pin contact points developed from each other along their length. A nonconductive cover removably fitted over the core and springs provides accessibility for spring replacement and protection against contact pin damage.

9 Claims, 2 Drawing Figures

Claims

1. In an electrical outlet for connection to an electrical cord without stripping the insulation from the cord, a body, a cord channel for said cord through said body adapted to hold an insulated conductor in a predetermined position, a contact channel in said body and extending toward said cord channel, said contact channel being adapted to receive the projecting prong of an electrical connector, a contact within said body, said contact having a portion in said contact channel adapted to make electrical connection with a prong upon insertion of the prong into the channel, said contact being provided with a pointed end, said pointed end being directed toward said predetermined position of the conductor in said cord channel, and means to reciprocate said contact into and out of said cord channel, said means including means separate from said sharpened end of said contact to secure said conductor in said channel, said means for reciprocating said contact further including means to prevent reception of prongs into said contact channel when said contact is withdrawn from said cord channel.

2. The device of claim 1 in which said means for moving said contact comprises a generally cylindrical shaft adjacent said contact, a helix on said shaft, fixed means on said body extending into engagement with said helix adapted to cause said shaft to move axially with respect to said body upon rotation of said shaft, and a rotatable connection between said shaft and said contact adapted to move said contact axially upon axial movement of said shaft.

3. The device of claim 2 in which the rotatable connection between said shaft and said contact comprises a groove in said shaft and a protuberance on said contact extending into said groove.

4. The device of claim 3 in which said protuberance on said contact consists of a flange extending into said channel, said flange being struck up from the material of which the contact is made.

5. The device of claim 2 in which said shaft is provided with a generally circular head extending radially from said shaft at the top of said body sufficiently to cover the contact channel for reception of the prong of an electrical plug, and a recess in the margin of said head of sufficient depth to expose said channel for the reception of the said prong of an electrical plug, said recess being so positioned with respect to said helical means as to expose said channel for reception of a plug prong only when said shaft is at its positioN axially furthest into said body.

6. The device of claim 2 in which said shaft is provided with a generally conical protuberance at its inward end adapted to enter said cord channel when said shaft is in its axially inward position and bear against a conductor in said cord channel whereby it prevents movement of said cord with respect to said body.

7. The device of claim 6 in which the cord channel is relieved axially away from said shaft at the point where said shaft enters said cord channel whereby pressure of said shaft against a cord in said channel forces the cord into the relief.

8. In an electric cord set, a multiple conductor cord having a plug at one end and a single outlet at the other end, a movable outlet intermediate the ends of said cord, said movable outlet comprising a body having a cord channel through which said cord extends, cord clamping means movable axially into and out of said channel, means to cause said axial motion of said clamp means upon rotation of said clamp means, a plurality of contacts each having a pointed end adapted to move axially to and from engagement with a respective conductor with said clamp means as said clamp means is rotated, openings in said body adapted to receive the prongs of an electrical plug, and means attached to said clamp means to block said prong openings until said clamp means and said points are moved axially into said cord channel.

9. The device of claim 8 in which said body is provided with an integral protuberance, said clamp means comprising a shaft provided with a helical screw thread engaging said protuberance, said openings for said plug contacts comprising a pair of parallel channels extending at right angles to said cord channel, said outlet contacts being U-shaped and having a short end portion of the U extending along the side of the respective plug openings and a long leg portion of the U extending alongside the shaft of the clamp means, said shaft being provided with a circumferential groove and said outlet contact being provided with flanges entering said groove.

10. For making strain relieved contacts with an insulated electrical conductor, a body having a channel to receive said insulated conductor, an electrical contact having a point adapted for axial movement toward and into the channel and through the insulation to make electrical contact with said conductor, a strain relief member adapted to move axially into contact with the insulation of said conductor to apply pressure thereto against the wall of said channel, an opening in said body providing access to said contact member for making an electrical connection thereto, and means operated by said strain relief member preventing access to said last mentioned opening when said strain relief member is not in a position in which pressure is applied to said electrical insulation, and having an opening permitting such access when said member is in pressure applying position.

11. The device of claim 10 in which the contact and the strain relief member are connected for simultaneous axial movement into said channel.