US 3686616 A
A cam shaped prong on one part locks with a shouldered portion of another part by pressing one against the other. The parts are separated by an angular relative motion causing the prong to pivot and disengage. In one embodiment, the fastener is in the form of a removable cover as a protective device for temporarily blocking the socket of an electrical outlet. The cover is formed of a resilient, flexible material having a tab on one side and a pair of spaced prongs on the other side. The prongs are formed with facing shoulders which latch onto a socket when pressed therein. The prongs also are configured with cam surfaces which work against the edges of the socket to produce a spreading motion of the prongs when the cover is rotated whereby it may be released from the socket.
Claims available in
Description (OCR text may contain errors)
owerman 41 FASTENER  Inventor: William R. Bowerman, 2457 Jasu Dr., Lawrence, Kans. 66044  Filed: Dec. 21, 1970  Appl. No.: 99,994
 US. Cl. ..339/38, 24/208 A, 24/73 P, 24/201 S, 24/221 R  Int. Cl. ..A44b 17/00  Field of Search ..24/208 A, 73 P, 107, 201 S, 24/204, 213, 208, 113, 73 PF, 73 S, 73 AP, 230 TC, 230 F, 230 SL; 339/38, 36; 248/223;
[ 1 Aug. 22, 1972 3,387,252 6/1968 Rothweiler ..339/38 FOREIGN PATENTS OR APPLICATIONS 935,829 9/1963 Great Britain ..339/38 729,314 3/1966 Canada ..339/38 Primary Examiner-Bemard A. Gelak Attorney-Morse, Altman & Oates ABSTRACT A cam shaped prong on one part locks with a shouldered portion of another part by pressing one against the other. The parts are separated by an angular relative motion causing the prong to pivot and disengage. In one embodiment, the fastener is in the form of a removable cover as a protective device for temporarily blocking the socket of an electrical outlet. The cover is formed of a resilient, flexible material having a tab on one side and a pair of spaced prongs on the other side. The prongs are formed with facing shoulders which latch onto a socket when pressed therein. The prongs also are configured with cam surfaces which work against the edges of the socket to produce a spreading motion of the prongs when the cover is rotated whereby it may be released from the socket.
7 Claims, 17 Drawing Figures Patented Aug. 22, 1972 .2 Sheets-Sheet l M/VE/VTOR WILLIAM R. BOWERMAN B) 7%,, Ow, 105E:
ATTORNEYS Patented Aug. 22, 1972 3,686,616
.2 Sheets-Sheet 2 F/G. /Z
62 0 U F/G /3 58 WILLIAM R. BOWERMAN ATTORNEYS FASTENER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to fastening devices including locks and more particularly is directed towards a new and improved fastener of simplified construction, design and operation.
2. Summary of the Prior Art A wide variety of safety devices have been developed heretofore for use with electrical outlets designed to protect children against shocks or electrocution as the result of inserting metal parts into a socket. Since many infants and children have been injured in this fashion, considerable effort has been directed towards protective devices which permit opening of a socket. by an adult but not by a child. Most devices of this nature have been relatively complicated mechanical affairs employing such techniques as spring-loaded rotary or sliding plates which close the socket in one position and open the socket in another position. Devices of this nature are relatively expensive and usually require the services of an electrician to install. Furthermore, the spring components frequently fail with the result that the effectiveness of the device is lost.
Accordingly, it is one object of this invention to provide a new and improved general purpose fastener of simplified construction, particularly adapted for use as a safety cover for electrical outlets or for other locking and fastening applications. A further object of this invention is to provide a low-cost safety cover for electrical outlets which cover is easily installed and removed by an adult but difficult to operate by a child.
SUMMARY OF THE INVENTION This invention features a fastening device comprising a first member having a hook-shaped cam engageable with a shouldered second member by pressing the parts together. The parts are disengaged by a rotary motion of the parts whereby the cam portion cooperates with the shoulder portion to bias the cam out of locking engagement. In one embodiment it is used with an electrical socket having a pair of spaced openings with shoulders formed in the walls of the socket and comprises a body portion of slightly flexible material, the body portion being formed on one side with a pair of spaced prongs dimensioned for insertion in the sockets. The prongs are provided with oppositely facing hooking portions having leading cam portions adapted to spread the prongs apart when the device is inserted straight into a socket until the hooking portions snap onto the shoulders of the socket. The cam portions are extended along the prongs in a manner to cause a spreading motion of the prongs when the body is rotated so as to release the prongs from the socket shoulders.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in perspective of a safety cover made according to the invention,
FIG. 2 is another perspective view showing the opposite side of the device,
FIG. 3 is a view in front elevation of the safety cover,
FIG. 4 is a view in rear elevation thereof,
FIG. 5 is a view in side elevation thereof,
FIG. 6 is a cross-sectional view taken along the line 66 of FIG. 4,
FIG. 7 is a top plan view of the device,
FIG. 8 is a fragmentary perspective view showing an electrical outlet with one cover in position,
FIG. 9 shows a cover being inserted in an electrical socket,
FIG. 10 shows the cover in full locking position,
FIG. 11 shows the cover being removed from the socket by a twisting action,
FIG. 12 is a top plan view of a modification of the invention,
FIG. 13 is a perspective view showing another modification of the invention,
FIG. 14 is a detailed sectional view of the FIG. 13 embodiment,
FIG. 15 is a perspective view of the prong member,
FIG. 16 is a perspective view of a further modification of the invention, and,
FIG. 17 is a perspective view of the FIG. 16 prong member.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings there is illustrated a fastener made according to the invention as embodied in a protective cover plate for an electrical outlet. The device is generally organized about a circular body portion 10 of a slightly resilient, flexible and electrically insulating material such as plastic or the like. The body portion, on its outer face, is provided with an integral semi-circular tab 12 for gripping the device and on its opposite face is provided with a pair of spaced prongs 14 and 16, also integral with the body portion.
The prongs l4 and 16 are spaced apart from one another in parallel opposition. Each of the prongs is formed with a relatively wide, base portion 18 rising smoothly from a flat rear surface 20 defining the back face of the body 10. The base portion of the prongs, as viewed in side elevation, extends to an apex 22 from the face 20 defining inwardly projecting hook or shoulder portion 32. The shoulder portion 32 extends towards a similar shoulder portion on the opposite prong and the edges thereof are faired smoothly into the curved edges 24 and 26 of the prongs. Thus in rear elevation, each shoulder portion 32 defines a smooth protuberance 34 defining a cam surface together with the edges 24 and 26.
Referring now more particularly to FIGS. 8 through 11, there is illustrated the cover in conjunction with a socket 36 of an electrical outlet generally indicated by the reference character 38. In a typical socket for an electrical outlet, a pair of spaced slots 40 and 42 are formed in a face plate 44 in register with electrically conductive contacts 46 and 48 which normally receive the prongs from an electrical plug inserted in the socket. The face plate 44 includes a central web portion 50 having inwardly facing shoulders on either edge thereof adjacent the slot openings 40 and 42.
As shown in FIG. 9, when the device 10 is to be plugged into position, the prongs 14 and 16 are aligned with the slot openings 40 and 42 the device is pushed into the socket. The inward pressure causes the prongs to spread apart, bending the body portion 10 as shown in FIG. 9. The spreading action is caused by the cam protuberances 34 of each prong riding over the outer edges of the central portion 50 until they snap into locking engagement with the inner edges of the portion 50, as best shown in FIG. 10. In this condition, the body portion overlays the outer part of the socket, effectively closing it so that a child would be unable to injure himself by innocently inserting a metal instrument into the socket. In this position the device cannot be pulled away from the socket by virtue of the hook portions locking with the shoulders of the face plate.
The device can be removed only by twisting the device about its axis in the manner shown in FIG. 11. This is done by grasping the tab 12 and turning the device in a clockwise or counterclockwise direction. The twisting of the device causes the curved edges 24 and 26 of the prongs together with the cam portion 34 to produce a spreading action of the prongs. The cam surfaces of the prongs, under the turning action, ride against the socket edges, forcing the prongs apart to an extent sufficiently for the hook portions 32 to clear the central portion 50 of the face plate. Once the hook portions are clear of locking engagement with the face plate and the body portion distorted in the manner shown, the device is easily withdrawn.
While the device is shown in use as a safety cover plate for an electrical outlet, it could be used with equal advantage for other fastening applications in which two parts are to be detachably connected to one another.
Referring now to FIG. 12, there is shown a modification of the invention and in this embodiment a body portion 10 is of rigid material while prongs l4 and 16' are made up of two sections connected by a spring loaded hinge 52. With this construction, the device need not be flexible the hinged prongs pivot on their hinges when the device is twisted in a receptacle.
In this embodiment of FIGS. 13 and 14 a single prong member 54 is used with a striker plate 56 in a lock system such as for an automobile door. The prong member is pivotally mounted to a yoke 58 and normally urged clockwise as viewed in FIG. 14 by springs 60 to lock against the plate when the prong member and plate are pushed together. The yoke 58 is fixed to a shaft 62 pivotally supported in bearing 64, the shaft being operated by a crank arm 66 engaging a shipping rod 68. Handles 70 and 72 pivoted to a fixed frame engage each end of the rod 68 whereby the yoke and its member 54 may be rotated from either point to disengage the member from the plate, the prong member working against the edge of the plate as in the principal embodiment.
Referring now more particularly to FIGS. 16 and 17 there is illustrated a further modification of the invention and, in this embodiment, a prong member 74 is rotatably mounted to an axially movable rod 76 slidably mounted to a fixed yoke 78. The member 74 is restrained against axial displacement with respect to the rod but is rotatably mounted thereto being normally urged in a clockwise direction by springs 80. The springs serve to keep the prong member 74 engaged with a striker plate 82, apply opposing axial pressure to keep the prong member in the center of the striker plate aperture and return the prong member 74 and its rod 76 to a center position after disengagement from the plate. Unlocking action involves an axial displacement of the rod 76 together with the prong member to the right in FIG. 16 which will cause the contoured prong member, working against the striker plate, to
rotate ounter loc 'se and dise a e. nsofar th unlocking motion ifs i n one direci n oniy one side 0 the prong member need be cam contoured as best shown in FIG. 17.
Having thus described the invention what I claim and desire to obtain by Letters Patent of the United States is:
1. A fastener for engaging a member formed with a pair of sockets and shoulders recessed therein, comprising,
a. a body portion formed with at least one surface,
b. a pair of movable prongs extending outwardly from said body portion in a first direction perpendicular to said surface,
c. resilient means normally urging one of said prongs in a second direction perpendicular to said first direction,
. said one prong being formed with a substantially flat shoulder substantially parallel to said surface and being along the portion only of said one prong that faces the other prong and adapted to engage the shoulder of said member,
e. said one prong being formed with an inclined leading face extending from the apex thereof to the outer terminus of said prong shoulder and adapted to ride against said member during a locking motion in said first direction whereby said one prong will be displaced in a direction opposite said second direction and then return in said second direction when said shoulders align,
f. said surface and said prong shoulder being spaced apart by a distance substantially corresponding to the depth of said member shoulder to limit the locking motion therebetween,
g. said one prong being formed with sloping cam edges adjacent said prong shoulder and said face in position to engage the edges of said member shoulder when said body portion is twisted about an axis parallel to said one direction to cause said one prong to move in said opposite direction and disengage said shoulders.
2. A fastener according to claim 1 wherein said body portion includes a pair of spaced oppositely facing matching prongs adapted to engage a pair of similarly spaced sockets.
3. A fastener according to claim 2 wherein said fastener is formed of a resilient material.
4. A fastener according to claim 2 wherein said prongs are hinged to said body portion.
5. A fastener according to claim 2 including a tab extending from said body portion on the side opposite said prongs.
6. A fastener according to claim 2 wherein said body portion is a circular disc and said prongs are in spaced parallel relation on one face thereof.
7. A fastener according to claim 1 wherein said one prong is pivoted to said body portion about a first axis, means mounting said body portion for angular movement about a second axis normal to said first axis, and linkage means connected to said body portion for an gular movement thereof.