US3543221A - Pressure lock terminal - Google Patents

Description

Nov. 24, 1970 J. SCHMIER 3543,22?

PRES SURE LOCK TERMINAL Filed Aug. 27, 1968 f2 Sheets-Sheet 1 INVENTOR. JACOB SCHMIER ATTORNEY.

Nov. 24, 1970 J. SCHMIER 3,543,221

PRESSURE LOCK TERMINAL Filed Aug. 27, 1968 2 SheeLs-Sheet 2 INVENTOR JACOB SCHMIER CKF W Vjf L'wvv ATTORNEY.

United States Patent 3,543,221 PRESSURE LOCK TERMINAL Jacob Schmier, Allentown, Pa., assignor to Rodale Manufacturing Company, Inc., Emmaus, Pa., a corporation of Pennsylvania Filed Aug. 27, 1968, Ser. No. 755,672 Int. Cl. H01r 11/20 US. Cl. 339-95 6 Claims ABSTRACT OF THE DISCLOSURE A single piece of sheet metal stock is formed to provide a pressure-lock terminal strip.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a pressure-lock terminal strip for an electrical wiring device.

Description of the prior art A pressure-lock terminal strip is one in which the pressure-lock terminal does not require screws or the like for connection of the conductor wire to the strip. An example of such a terminal is shown in Ehrlich Pat. No. 2,952,831, dated Sept. 13, 1960.

SUMMARY OF THE INVENTION An object of the invention is to simplify the construction of a pressure-lock terminal strip by provision of wire engaging means that is extremely simple in form, and by provision of fully adequate wire guiding means without any special forming of the strip. In addition, when the strip is provided with a plurality of pressure-lock terminals, each wire engaging element may be operated without affecting the other, either to secure a wire or release the wire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a duplex plug receptacle having a portion of its cover broken away to expose one of the terminal strips, the other terminal strip being removed to expose certain details of the base;

FIG. 2 is a longitudinal section on line IIII in FIG. 1;

FIG. 3 is a transverse section on line III-III in FIG. 1;

FIG. 4 is a side view of the terminal strip alone, as indicated by the line IVIV in FIG. 1;

FIG. 5 is a plan view of a partially formed blank from which the terminal strip is fabricated;

FIG. 6 is a fragmentary view showing engaging element; and

FIG. 7 is a fragmentary view showing another modified wire engaging element.

a modified wire DESCRIPTION OF THE PREFERRED EMBODIMENT The following description is directed to the specific embodiment of the invention disclosed in the drawings. It is not addressed to the scope of the invention, which may be practiced in a variety of forms.

Referring to the drawings, the duplex wiring receptacle, generally designated 10, comprises a hollow base 12, a cover 14 and a supporting strap 16 suitably secured together by means not shown. The vase 12 and cover 14 ice preferably are made of Bakelite, and the strap 16 is made of suitable sheet metal. The base 12 is provided with a partition consisting of a hollow boss 22 and a pair of sections 24 conjointly dividing the interior of the base 12 into laterally spaced compartments 26. Extending laterally respectively from opposite sides of the boss 22 are a pair of walls 28 sub-dividing the compartments 26. Each compartment 26 accommodates a contact and terminal strip 30 formed from a blank of electrically conductive material, such as brass or the like. The blank, generally designated 32, is shown in partially formed condition in FIG. 5.

Referring to FIG. 5, the blank 32 has a main body part 34 at each end of which is suitably formed a set of spring contact elements 36 and 38. Depending from the elements 38 is an arm 40 terminating in a lateral extension thereof designated 42. The extension 42 carries a wire engaging arm or element 44. The part 34 is centrally recessed, as at 46, and is provided with a pair of openings 48 respectively on opposite sides of the recess. The lower marginal portion of the part 34 is provided with a pair of struck out tabs 50 respectively on opposite sides of the recess. The upper marginal area of the part 34 is provided with a tab 52 turned outwardly from the plane of the part 34 and disposed over the recess 46. It is also provided with a pair of upright tabs 54 respectively on opposite sides of the tab 52.

In completing the forming of the blank, the opposite end portions thereof are bent at right angles to the part 34, upon the lines A-A, to form a pair of shoulders 56. Then the contact elements 36 and 38 are suitably formed (as shown) for receiving therebetween the contact blades (not shown) of an attachment plug inserted through the usual openings in the cover 14. In addition, the arms 40 are turned upwardly on lines B-B to position the arms 40, the extensions 42 thereof and the wire engaging elements 44 in coplanar relation.

Each part 34 is provided with a pair of screws 58 respectively threaded into the openings 48 and is disposed in a vertical plane, against the opposed outer wall of the base 12, with the opposite sides of the recess 46 engaged respectively in a pair of grooves 60 formed in the associated wall 28. When the strip 30 is thus positioned, the shoulders 56 respectively are disposed close adjacent a pair of bosses 62 formed on the bottom surface of the compartment 26. In addition, the innermost portions, designated 64, of the contact elements 38 respectively are disposed close adjacent the walls 24. Thus it will be seen that the strip 30 is secured against longitudinal and lateral movement in the compartment 26. When the cover 14 is positioned over the base 12, the tab 52 abuts the undersurface of the cover, and the pair of tabs 54 respectively are received in depressions (not shown) formed in the undersurface of the cover 14, providing further against movement of the strip 30 in the compartment 26.

Initially, the arm 40 and wire engaging element 44 of strip 30 are seated upon the bottom surface of the compartment 26. The lateral extension 42 of the arm 40 overlies a depression 66 in the bottom surface of the compartment, next to the associated wall 28, which depression forms a shoulder 68. The extension 42 overhangs the shoulder 68. Overlying the extension 42 is the associated tab 50.

The lower corner at the free end of the wire engaging element 44 forms a sharp edge which bites into the bared end portion of a conductor Wire C when the same is projected into the receptacle through an opening 70 in the bottom of the base 10. The opening 70 is located so that the wire is projected upwardly into the angle or corner former on the inside of the shoulder 56, along the bend AA, as shown. Thus the wire is pressed into good electrical contact with the surfaces meeting at said corner, which surfaces coact to guide the wire into the desired position. It will be noted that when the wire is inserted through the opening 70, it raises the wire engaging element 44 and turns the lateral extension 42 of the arm 40 down into the depression 66. The wire engaging element 44 and the lateral extension 42 remain coplanar. It will be appreciated, therefore, that the arm 40 bends over the shoulder 68 at the juncture thereof with its lateral extensions 42. The function of the tab 50 is to assure that the arm 40 and its lateral extension 42 are not raised with the wire engaging element 44 by the wire, and to coact with the shoulder 68 in assuring the desired pivoted movement of the wire engaging element 44 and the lateral extension 42 of the arm 40 as a unit about the shoulder 68 relative to the arm 40.

If a pull is applied to the wire to remove it from the receptacle, the sharp corner of the wire engaging member 44 bites into the wire and prevents withdrawal thereof. The downward pull on the wire tends to bend the end of the wire engaging element 44 downwardly, with the result that the wire is held more tightly in the corner in which it nests.

When it is desired to release the wire and to disconnect the same from the receptacle, a suitable tool (not shOWn) is projected through an opening 72 formed in the bottom of the base 10. The end of the tool engages the undersurface of the wire engaging element 44 intermediate the end thereof, at a point spaced from the associated tab 50, and raises it, thus effecting disengagement of the wire engaging element 44 from the wire, whereupon the wire may be removed. When the wire is removed and the wire engaging element released, the inherent resilience of th spring metal out of which the strip 30 is fabricated causes the wire engaging element 44 and the lateral extension 42 of the arm 40 to spring back to their initial positions. The metals usually used for forming contact and terminal strips provide sufiicient spring action for functioning of the wire-engaging members in the manner indicated.

The free end of the wire engaging element 44 is spaced from the opposed portion of the contact element 38 a distance slightly less than the diameter of the smallest conductor wire that is to be connected to the receptacle so that the spring pressure of the wire engaging element will hold the wire firmly thereagainst and in good electrical contact therewith. Within limits, the flexing of the wire engaging element will also allow larger diameter wires to be inserted.

It will be noted that the arm 40 are not interconnected in any way except through the parts 34, and that they branch off respectively from opposite ends of the strip 30 independently of each other. As a consequence, when either wire engaging element 44 is flexed, either when a wire is inserted into the receptacle for connection thereto or when a tool is inserted into the receptacle to release a wire therefrom, the other wire engaging element is unaffected so that there is no danger of loosening the grip of the other wire engaging element on a wire held in place thereby.

While in accordance with the provisions of the patent statutes, I have illustrated and described the best form or embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the device described without departing from the spirit and scope of the invention. For example, referring particularly to FIG. 6, the terminal edge 74 of the free end portion of the wire engaging element 76 is cut at an angle so that when a conuctor wire is projected into the device, it is cammed into the corner formed by the main body part 78, as shown. In addition, referring particularly to FIG. 7, the terminal edge 80 of the free end portion of the wire engaging element 82 is recessed so that when a conductor wire is projected into the device, it is guided by said free end portion and held firmly against the main body part 84.

Having thus described my invention, I claim:

1. Pressure-lock terminal means for an electrical wiring device, said means consisting of a single sheet metal stamping of electrically conductive metal including (A) a main body part having opposite end portions turned in the same direction from a central portion and disposed approximately at right angles thereto,

(B) a pair of J-shaped appendages turned inwardly respectively from said opposite end portions of the main body part and disposed approximately at right angles thereto, each of said appendages including (1) a first arm extending away from the associated end portion of the main body part, (2) a lateral extension of said arm, and (3) a second arm disposed between said first arm and the central portion of said main body part and extending from said lateral extension back toward the associated end portion of the main body part, the terminal edge of the free end portion of said second arm being set back from the associated end portion of said main body part a distance less than the diameter of the conductor wire to be accommodated by said pressure-lock terminal.

2. A pressure-lock terminal means according to claim 1 wherein the terminal edge of the free end portion of each second arm is disposed at an angle, the line thereof extending across the corner formed by juncture of the associated end portion of the main body part with the central portion of the main body part, said terminal edge being operative to cam a conductor wire projected into said terminal means, between said terminal edge and main body part, into said corner for guidance thereof.

3. A pressure-lock terminal means according to claim 1 wherein said means is housed in a casing provided with openings for receiving the conductor wires and guiding the same respectively into the corners at the junctures of the opposite end portions of the main body part with the central portion of the main body part for further guidance thereby.

4. A pressure-lock terminal means according to claim 3 wherein at each end of said means the lateral extension of the first arm overlies an area of the bottom surface of the casing which is depressed whereby to form a shoulder extending across the first and second arms at the juncture of said arms with the lateral extension of said first arm, and the main body part carries means disposed in close overhanging relation to said lateral extension of the first arm overhanging said shoulder, the last mentioned means being operative to secure said first arm and said lateral extension of the first arm against being raised with said second arm when a conductor wire is projected into the terminal.

5. A pressure lock terminal for an electrical wiring device, said pressure lock terminal consisting of a single sheet metal stamping of electrically conductive metal including (A) a main body part, and

(B) a generally J-shaped appendage disposed in a plane approximately at right angles to said main body part including (1) a first arm extending from said main body part in a first direction,

(2) a lateral extension of said arm, and

(3) a second arm extending from said lateral extension back in a direction opposite to said first direction, the terminal edge of the free end portion thereof being set back from the opposed area of said main body part a distance less than the diameter of the conductor wire to be accommodated by said pressure lock terminal, and

(C) means carried by said mean body part and disposed in close overhanging relation to the lateral extension of the first arm, said means being operative to secure the first arm and said lateral extension 5 of the first arm against being raised with said second arm when a conductor wire is projected into the terminal.

6. A pressure-lock terminal according to claim 5 wherein the main body part comprises two portions which meet to form a corner proximate the terminal edge of the free end portion of the second arm, said pressure-lock terminal is house in a casing with an opening therein for receiving the conductor wire and guiding the same into said corner for further guidance thereof, and the lateral extension of the first arm overlies an area of the bottom surface of the casing which is depressed whereby to form a shoulder extending across the first and second arms at the juncture of said arms with the lateral extension of said first arm.

References Cited UNITED STATES PATENTS Benander 339164 Strange 339-95 Ehrlich 33995 Munroe 339-95 US. Cl. X.R.

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