US 2911614 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Nov. 3, 1959 w. w. DAVIS 2,911,614
POLARIZED OUTLET AND PLUG l Filed oct. 22, 1957 77 79 3o `E J 56" If *Q n: 9? 9 m" INVENTOK. o 3 ,6, Zygfieffl@ 76 WWMWMT'W United ,States Parent IO j 2,911,614 lPoLRIzED OUTLETAND PLUG 'j Walter W. Davis, Campton, N.H. n Application october zz, I1951, serial isa-691,711
This invention relates to electrical connector. devices, and more particularly to a polarized receptacle and plug arrangement for use in conjunction with domestic' power systems of the type having a grounded conductor.
A main object of the invention is to provide a novel and improved polarized receptacle and plug for. use therewith, thereceptacle and plug being especially suitable for use ini conjunction' with conventional electric wiring includinga grounded conductor, the receptacle and plug being simple in construction, being easy to install, and providing a means whereby appliances of the polarized type may be properly connected to the line conductors for energizing same.
A further object of the invention is to provide an improved polarized plug and receptacle for use therewith;
the plug and receptacle being inexpensive to manufacture, beingl durable in construction, being arranged so that correct polarity is positively maintained, the receptacle being neat in appearance, and the plug and receptacle being easily connected together.
A still further object ofthe invention is to provide an improved plug receptacle of the polarized type.es.
pecially suitable for use in conjunction with domestic wiring systems, the receptacle being compact in size, b'eing arranged to firmly hold a plug inserted therein, and being provided with spacing between the contacts thereof of suicient magnitude to insure that no short circuits will occur in the receptacle.
Further objects and advantages of the invention will become .apparent from the following description and claims, and from the accompanying drawings, wherein:
Figure l is a vertical cross sectional view taken through an improved polarized receptacle according tothe present invention, shown withfa polarized plug engaged therein.
Figure 2 is anV enlarged longitudinal vertical cross sectional view taken through the plug employed in Figure 1.
Figure 3 is a transverse vertical cross sectional view taken on the line 3-3 of Figure 2.
Figure 4 is a top VView of the main body portion of the plug of Figures 2V and 3, the outer cover thereof being removed.
Figure 5 is a transverse vertical cross sectional view taken on the line 5-5 of Figure 2. i
Figure 6 is a horizontal cross sectional view taken on the line 6-6 of Figure 1.
Figure 7 is a horizontal cross sectional view taken on the line 7-7 of Figure l.
Figure 8 is a cross vsectional view taken on the line 8 8 of Figure 6.
Figure 9 isv a cross sectional view taken on the line 9-9 of Figure 6. v Y i Figure l0 is a fragmentary horizontal cross sectional View taken on the line 10`10 of Figure 2.
, Figure l1 is a fragmentary vertical cross sectional viewA taken through the upperportion of a modified form of polarized plug receptacleaccording to the` pres# Patented Nov. 3, 1959 ICC 2 ent invention adapted for a three-wire circuit and shown with a three-contact plug engaged in the receptacle.
Figure 12 is a top plan view of the main body portion of the threecontact plug employed in Figure l1.
vFigure 13 is a transverse vertical cross sectional view taken on the line 13-13 of Figure l2.
Referring to the drawings, and more particularly to Figures/1 to 10, 14 designates a conventional outlet box provided with a suitab-le receptacle-supporting strap 15 in which is secured a polarized plug receptacle according to the present invention, and designated generally at 16.
The receptacle 16 comprises a pair of opposed, hollow, mating, generally rectangular housing segments 17 and 18 .of rigid insulating material, such as rigid plastic material, the-hollow segments 17 and 18 being secured together in opposing relationship to dene a rectangular housing by an internally threaded sleeve member 21 having head portions 22 and 22 4at its opposite ends. The` sleeve member 21 extends through a central aperture in the'bight portion of the receptacle bracket member 15=fand acts as a hollow rivet to fasten members 15, 17 and 18 together. A machine screw 19 extends through the center portion of a rectangular face plate l20 and is threadedly engaged in the internally threaded sleeve member 21.
The sleeve 21 passes through a central, generally rectangular spacing block 25 of rigid insulating material whichfits snugly in the intermediate portion of the cavity l:defined between the opposing housing segments 17andV 18. Clamped between block Z5 and the major wall of housing segment 17 is a rear contact plate Z6, clearly shown in Figure 9, said contact plate being genrally V-shaped and being formed at its opposite ends with apertures 27, 27 adapted to receive the ball end of a connecting plug, presently to be described. The end portions of the terminal plate 26 are fonned with inwardly extending spring contact ngers 28 which are spaced around the apertures 27, as shown in Figures l and 9,Y said contact fingers 2S being adap-ted to receive the ball end 30 of a plug therebetween and to exert a locking action on said ball end to retain the plug in the receptacle, as will be presently explained.
'The intermediate portion of the terminal plate 26 is formed with a terminal flange 31 exposed through a notch inthe adjacent side wall of housing segment 17, as shown in Figure 6, said flange 31 being provided with terminal screws 33 which provide a means for electrically connecting terminal conductor 34 to the terminal plate 26.
Clamped between the block 25 and the inside surface of the major wall of housing segment 18 is a generally V-shaped terminal plate 35, said terminal plate being formed at its end portions with ring-like members 36, 36, defining apertures similar to the apertures 27, said ringlike members 36,Y 36 being formed with inwardly projecting, spaced spring contact fingers 37 adapted to conductively and grippingly engage with the conductive sleeve portion 56 of a plug 39 when the contact plug is inserted in the receptacle in the manner illustrated in Figure 1. The terminal platemember 35 is provided at its intermediate portion with a terminal Flange 40 rwhich is exposed through a notch in the side wall of housing segment 18, as shown in Figure 6, said ange 40 being provided with terminal screws 42. The terminal screws 42 are vadapted -to be connected to the grounded conductor 44 of a house wiring system.
As shown in Figures 8 and 9, the fastening sleeve 21 extends vthrough the aligned contact plates 26 and 35, being;I located substantially midway between and in the same' plane as the axes of the ring-like members at thek ends'of said plates. i
As shown inFigure 1, the housing segment 18 is formed with conical, inwardly convergent apertures 45' 3 aligned with the spaced apertured end portions of the respective terminal plates 26 and 35.
The plug 39, above mentioned, comprises a main body 46, of suitable insulating material, said main body having integrally moulded therein the shank member' 47 whose outer end is formed with the ball contact element 30. A terminal screw 48 is engaged through the inner end of the shank 47 and is adapted to electrically conlnect a conductor 49 to said shank member 47, the conductor 49 forming part of `an appliance cord 50, as shown in Figure 2.
The body 45 is formed with a reduced for-ward portion 51 and with a conical shoulder 54 adapted to it the conical apertures 45 in the front wall of housing section 18. A grooove 52 is formed between the forward end of the reduced portion 51 and the conical shoulder 54, and positioned in this groove is a contact sleeve member 56 having a stem portion 57 moulded in the body 54 andv extending a substantial distance inwardly thereof. A terminal screw 58 extends through the inner end of the stem 57 and is threadedly engaged in the body 46, the shank 47 being bowed at its intermediate portion, as shown at 59 in Figure 10, to provide clearance between said shank portion and the terminal screw 58. The remaining conductor 60 of the line cord 50 is adapted to be connected to the terminal screw 58, and hence to the contact sleeve 56. As shown in Figure 4, the contact sleeve 56 is substantially ilush with the forward portion 51 of main body 46, and is coaxially arranged with re-v spect to the shank 47.
Designated at 62 is a cover member which is securedy over the rear portion of the plug body 46, as by means of a fastening screw 63 which extends through and is suitably insulated from the rear end portion of shank 47 and which is threadedly engaged inthe rear portion vofy body 46. The cover member 62 houses the terminal screws 4S and 58 and is preferably made ofinsulating material. Line cord 50 extends through an aperture 65 formed in the rear end wall of the generally cylindrical cover 62. v
As shown in Figure l, the plug 39 is easily inserted in the receptacle 16 through one of the conical apertures 45, the ball-shaped end 30 of the shank 47 being grippingly received betweenthe spring-like contact fingers `28 and being locked thereby, whereas the sleeve element 56 is conductively engaged by the resilient fingers 37 ofthe grounded terminal plate 35. Thus, positive assurance is4 provided that the line conductor 60 ofvcord 50 will always be connected to the grounded conductor of the wiring system, so that the appliance, if it -be of the polarized type wherein one conductor must be connected to the ground wire of the electric supply system, will lways be connected to the supply circuit' with the proper polarity.
In the form of the invention shown in Figures 1.1, "12' and 13, the receptacle, designated generally at 1'6 is provided with a third terminal plate 70 spaced between the inner terminal plate 26 and the outer terminal plate 35 by respective insulating spacer blocks 71 and 7'2'*V through which the main fastening sleeve 21 passes.Y The intermediate terminal plate 70 is provided with apertures, around which are resilient contact lingers 74 adapted to;
gaged in the inner end of the shank element of the plug, designated at 83. The respective Wires of a conventional three-wire line cord may be clampingly secured by the terminal screws 79, 81 and 82, and may be thus electrically connected respectively to sleeve member 75, sleeve member 56', and shank member 83 in the manner illustrated in Figure 12.
A generally cylindrical coverrg receives the rear end portion of the plug body 78 and is detachably secured thereto by a fastening screw 63 in the same manner as previously described in connection with the two-wire plug 39. A A
Thepolarized outlets and plugs above described are especially useful power tools and other electrical appliances requiring a special or second ground wire to provide safety against shock.
By the use of the present invention, the second ground or safety wire is eliminated, since the safety wire may be connected to the body of the tool or appliance itself, and thepolan'zed plug insures proper grounding of said body. rlfhis safety feature may be employed with all appliances.
` In wiring installations where Romex cable is used, the Outlet boxes are not grounded (unless special grounded Romex cable is used) thereby making the safety ground wire of thepower tool or appliance useless. By employing polarized outlets and plugs, according to this invention, in such installations, maximum protection against shock is provided at all times, using one line wire and one ground wire. v
While certain specic embodiments of an improved polarized receptacle and.' plug have been disclosed in the foregoing description, it will be understood that various Y- modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intendedthat no limitations be placed` on the'invention except as defined by the scope of the appended claims.
What is claimed is:
l. A plug receptacle for use with a plug of the type comprising a contact shank having a contact ball at its end and a contact sleeve surrounding said shank and insulated therefrom comprising a housing having parallel front and rear walls and opposite side walls, a first substantially V-shaped terminal plate secured to the inside surface of said front wall, a second substantially V-shaped terminal plate secured to the inside surface of said rear wall opposite said first V-shaped plate and parallel thereto, said front wall being formed with apertures to receive said plug, said terminalplates being formed with ringlike membersl at their ends defining apertures aligned with said first-named apertures, 'a transverse fastener extending through said front and rear walls and between the side arms of said V-shaped terminal plates in substantially the same'plane as the axes of said apertures, spring` conengage a terminal sleeve 75 on a threelwire plug 76, the
terminal sleeve 75 being spaced between and insulated from the ball end 30of the shank of the plug and the ground sleeve 56 of the plug. l i y As shown in Figure 13, the ground sleeve 56 is formed with a contact arm 77 which is moulded in and extends longitudinally of the main body of the plug, shown'af; 78, the arm 77 being threadedly engagedV by a` terminal screw 79, shown in Figure l2. The contact sleeve l75' is similarly formed with an arm 80 which is embedded.
in and extends longitudinally of the body 78, a terminalv f screw 81 being threadedlyengaged in the inner`l end of the afm` 89- A third tamirlslrserew Slis thtssdely sa' tact fingers on the first terminal plate extending inwardly and rearwardly from the apertures therein and being engageable with the contact sleeve of the plug, and springl contact lingers on the second terminal plate extending inwardly and-'forwardly from theapertures therein and being engageable with the contact ball of the plug.
Z. A plug receptacle for use with a plug of the type comprising a contact shank having a contact ball at its end-and a Contact sleeve surrounding said shank and insulated therefrom comprising a housing having parallel front andrear walls and opposite side walls, a rst substantially V-shaped terminal plate secured to the inside surface ofsaid front wall, asecond substantially V-haped terminal plate secured to the inside surface of said rear wall oppositetsaid first V-shaped plate .and parallel thereto, said front wall being formed with aperturestto receive said plug, said terminal plates being formed with ringlike members at theirends defining, apertures aligned with saidrst-named apertures, a transverse fastener extending through said front and rear walls and between the Side arms Of SaiSlV-Shsrsterminelplats ,iasubstsntally the same plane as the axes of said apertures, spring contact ngers on the terminal plate spaced around the apertures therein and extending inwardly and rearwardly, said contact ngers being engageable with the contact sleeve of the plug, and spring contact ngers on the second terminal plate extending inwardly and forwardly from the apertures therein, said last-named contact ngers being spaced around the apertures in the second terminal plate and being formed and arranged to receive and lockingly engage with the contact ball of the plug.
3. A plug receptacle for use with a plug of the type comprising a contact shank having a contact ball at its end and a contact sleeve surrounding said shank and insulated therefrom comprising a housing having parallel front and rear walls and opposite side walls, a trst substantially V-shaped terminal plate secured to the inside surface of said front wall, a second substantially V-shaped terminal plate secured to the inside surface of said rear wall opposite said rst V-shaped plate and parallel thereto, said front wall being formed with apertures to receive said plug, said terminal plates being formed with ringlike members at their ends defining apertures aligned with said first-named apertures, a transverse fastener extending through said front and rear walls and between the side arms of said V-shaped terminal plate in substantially the same plane as the axes of said apertures, spring contact fingers on the iirst terminal plate spaced around the apertures therein and extending inwardiy and rearwardly, said Contact lingers being engageable with the contact sleeve of the plug, spring contact'ngers on the second terminal plate extending inwardly Aand forwardly from the apertures therein, said last-named Contact ngers being spaced around the apertures in the second terminal plate and being formed and arranged to receive and lock- References Cited in the le of this patent UNITED STATES PATENTS 2,221,280 Woodside Nov. 12, 1940 2,228,683 Barrelle Jan. 14, 1941 Walton et al May 10, 1949