US 2209814 A
Description (OCR text may contain errors)
July 30,1940. l C H, HNGER 2;2o9,s14
' kELEQTRICM. CONNECTOR Filed Feb. e, 1940 QM, HIV
i ...f. "IIIIllnmmnulnluul HIIIIIIIIII Clinton H. Finger, by fa/ffMM/M Patented `luly 30, 1940 Unirse stares 2,209,814 l aLEo'rmoAL coNNEo'roa Clinton H. Finger, Milford, Conn., assignor to General Electric Company, a corporation of New York Application February 6, 1940, Serial No. 317,515
My invention relates to electric ,cord ,sets provided with detachable plug connectors of the type commonly used with electric household appliances.
An object of my invention is the provision of improved means for protecting the connection of the conductors of the cord set to the plug connector.
In the accompanying drawing, Fig, 1 is a view of the interior of a plug connector showing a strain relief means for securing an electric cord to the body of the connector; Fig. 2 is a perspec-v tive view, partly in section', of the strain relief means; Fig. 3 is a perspective View of the plug connector; and Fig. 4 is a perspective view of a portion of the strain relief means. V
Referring to the drawing, my plug connector Ill includes a housing II of insulating material, such as a phenolic condensation product and ller. .The housing is formed'in two parts of identical size and shape. The interior of 'onehalf of the housing is shown in Fig. 1 and is formed with spaced recesses I2 merging with an opening I3 at oneend for receiving an electric cord and associated strain relief means, the other 'end'tbeing provided with slots I4 for receiving the connector prongs of an electric appliance.
. A contact structure I5 is seated in each of the recesses I2 for making electrical contact with the appliance prongs, each contact being formed of opposed spring blades secured together at one. end and provided with a terminal screw I6. The contacts iioat freely within the recesses I2 to compensate for slight variations in the spacings of the appliance connector prongs. The 4two parts of the housing are held together in assembled relationship by any suitable fastening means, such as the screws I'l, which extend through the housing at points between the contacts.
An electric cord I8 extends through the opening I3 and is electrically connected to the plug connector; the cord comprises two insulated conductors I9 `protected by lan overall sheath 20 of `iibrous insulating material, such as acotton or rayon braid. The ends of the individual conductors are stripped, as shownat 2|, and are fastened to the contacts by the terminal screws IB.
In cord sets of the typedescribed it is important that the electric cord be secured to the connector in a manner such that strains or pulls on the cord will not be transferred to the elec; x trical connection between the conductors and the connector which result might seriously impair (ci. 11s-e322) or destroy the usefulness of the cord set. Moreover, the conductors of the cord should be pro-l tected in such a manner that they cannot become twisted or damaged within the body of the connector or at the point where they enter the 5 connector, in such a manner as to cause short circuits. To this end, I provide an insulating rubber sleeve 22 around the end of the electric cord at the point where it enters the housing Il. In l0 manufacture, the 'sleeve may be molded directly around the cord, or otherwise secured thereto, and is formed of flexible or resilient rubber. The sleeve 22 is provided with a perimetrical flange 23, which rests within a corresponding groove 24 l5 formed in the wall of the opening I3, so that 4longitudinal movement between the sleeve and insulating housing is prevented. This means that any pulls on the cord will be transmitted by the rubber sleeve to the housing of the con- 20 n ector and will not be transferred to'the connection of the conductors with the contacts I2.
, A flexible portion of the sleeve extends in tapered formation along the length of the cord and protects the cord from kinks orsharp bends at the 25 pointA where it enters the bodyv of the connector.
Relative movement between the rubber sleeve and the electric cord is prevented by placing a tie member 25 within the rubber. sleeve 22 and by winding the individual conductors I9 around the 30 member. This is of particular advantage'in those cases where the outer sheath ofthe electric cord is of brous material which does not bond easily to the rubber sleeve during lvulcanization of the latter. However, by this. construction an effec- 35 tive bond is secured between the conductors and the sleeve inasmuch as the tie member is embedded immovably within the rubber sleeve. By utilizing this construction, cord sets will withstand a pull of approximately fifty pounds be- 40 tween the cord and the body of the plug.
The member 25 disposed transversely of the rubber sleeve,` as shown most clearly by Figs. 1A andV 2, andl is located at a point substantially in i alignment Awith the flange 23, so that any stress 45 placed on this member is transferred to the sleeve and from the latter, through the medium of the flange 23, to the connector. The member 25 may be prvided with spaced pairs of grooves 26 for receiving the individual conductors Ato keep them 50 separate from one another.- In those cases where the bared ends of the conductors are wound, around the member, the latter may be formed of any suitable insulating material, such as wood or sheet ber. 55
In some existing constructions, transverse tie members have been disposed within connector housings sand. insulated conductors' wrapped around them to absorb pulls on the electric cord;
however, as far as I know, the use of a tie memassembly. Moreover, they cannot become unwrapped from the tie member being held in place by the rubber sleeve. This is of advantage if the plug is taken apart for repair since the strain relief is not disassembled. There isno danger of the bared wires 2l becoming twisted or dislocatedv ina manner to cause a lshort circuit of the connector. made of insulating materiaL-such as sheet ilber, the surrounding rubber` sheath protects it from heat incident to the use of thev connector on an electric' appliance; such as an iron or toaster. By; placing'the tie member within the rubber.
-sleeve a more compact jstructure is to be 'had inasmuch as space is not taken up by this member.
Withinthe' bodyof'the housing. The rubber sleeve -and tie member 25 are assembled as a unit ,by molding the rubber sleeve around dthe member at the same time that it is molded to the cord I8; this means that these elements may be mounted as a unit within the housing thereby effecting a considerablesaving in the cost of assembling the device.
Since the tie member 25 is preferablyA My invention is particularly applicable to those cord sets in which an electric cord having a iibrous jacket is applied to the plugsince it is diilicult to attain a good frictional bond'between the,f rubber sleeve and the jacket ofthe cord. However, it should be manifest that the invention is applicable equally as well to cord sets utilizing cords having other forms of insulating jackets such as all rubber jackets, although in such instances a good bond Vcan be secured between the rubber jacket and sleeve during vulcanizati'on oi' the latter to 'supplement the action oi the tie member 25.
What I claim as new and desire to secure by Letters Patentot the UnitedStates is: A
In a plug connector, a housing of insulating material having an opening at one end,` contact means within said housing for receiving the connectorf prongs of an electric device, an electric cord extending through said opening, the individual conductorsof said cord ,being connected tol corresponding contact means, a flexible resilient rubber sleeve surrounding and engaging said electric cord and being disposed in the opening in said housing, said sleeve having'a'fiexible por-vl tion extending outwardly from said housing along said electric cord, cooperatingmeans on said sleeve and housing to prevent relative longitudinal movement therebetween, and a tie member embedded in' and extending transversely of said rubber sleeve, the'individual conductors of said electric cord being wrapped around said tie' mem- A,r to prevent relative, sliding movement between said sleeve and said electric cord.'
., CLINTON H. FINGER..