US2727220A

US2727220A - Electric connector with set screw

Info

Publication number: US2727220A
Application number: US256432A
Authority: US
Inventors: Stephen N Buchanan; William F Mcguinness
Original assignee: Buchanan Electrical Products Corp
Current assignee: Buchanan Electrical Products Corp
Priority date: 1951-11-15
Filing date: 1951-11-15
Publication date: 1955-12-13
Anticipated expiration: 1972-12-13

Description

Dec. 13, 1955' s. N. BUCHANAN ETAL 2,727,220

ELECTRIC CONNECTOR WITH SET SCREW Filed Nov. 15, 1953 2 Sheets-Sheet IN V ENTOR. v

If 6 STEPHEN N BUCHANAN j W/LLMM F MCGU/NNESS ATTORNEK 1955 s. N. BUCHANAN EE'AL 2,727,220

ELECTRIC CONNECTOR WITH SET SCREW Filed Nov. 15, 1951 2 Sheets-Sheet 2 I N V EN TOR. STEPHEN N BUCHANAN WILLIAM F MCGU/NNESS A TTORNEK United States Patent ELECTRIC CONNECTOR WITH SET SCREW Stephen N. Buchanan, Westmoreland Hills, Md., and William F. McGninness, Union, N. J., assignors to Buchanan Electrical Products Corporation, Hillside, N. 1., a corporation of New Jersey Application November 15, 1951, Serial No. 256,432

4 Claims. (Cl. 339-272) This invention relates generally to electrical equipment and more specifically to an improved connector for electric current carrying conductors.

It is common practice in electrical wiring arrangements to afix a terminal lug on the bared end of an electrical conductor, connect the lug to a block that contains a plurality of spaced terminals, afiix a second terminal lug on the bared end of a second electrical conductor and connect the second lug to the terminal on the block in order to provide a continuous flow of current from the first conductor to the second. An object of this invention is to provide an improved connector that will eliminate this type of connection involving three different connecting points by causing the bared ends of the conductors to be mechanically and electrically joined directly together in the connector.

A further object of this invention is to utilize the advantage in lower electrical resistance that is afforded by a connection resulting from direct engagement of the conductors, as opposed to a connection involving an intermediary element between the conductors, as illustrated above.

A still further object of this invention is to provide an electrical connector that includes a movable clamping element permanently attached to the conductor re ceiving member of the connector.

An additional object of this invention is the provision of an improved connector that will mechanically unite two or more electrical conductors of the same or different commercial sizes.

The illustrated example of the invention includes an open-sided frame held upright on an anchor through an aperture in the top of the frame. A cap encloses the frame and the screw also passes through an aperture in the cap, so that the cap and the screw are movable as a unit relative to the frame. A shoe having a conductor-engaging portion immediately below the end of the screw has end portions engaging and held by the cap. Preferably the shoe can rock relative to the cap.

Other objects and advantages will be apparent from the description and the drawings, in which Fig. l is a perspective view of the screw;

Fig. 2 is a perspective view of an insulation jacket which may be used to cover the connector;

Pig. 3 is a perspective view of the frame member;

Fig. 4 is a perspective view of the cap member;

Fig. 5 is a view in perspective of the anchor block;

Fig. 6 is a view in perspective of the shoe member before it is assembled with the cap;

Fig. 7 is a perspective view of the locking member;

Fig. 8 is a View in perspective of the screw, frame, cap and shoe members in assembled form;

Fig. 9 is a side view in section of the assembled conneetor uniting two conductors;

Fig. 10 is a side view, partly in section, of the assembled connector with the insulation jacket inserted there over;

Fig. 11 is a perspective view of the cap member showing the relationship of the tongues after the clamp screw initially contacts them; and

Fig. 12 is an end view, partly in section, of the connector showing filler inserted in the bottom of the connector.

Referring to the drawings, reference numeral 10 indicates a frame member which may be formed by bending a metallic strip, of oblong form, into a rectangular configuration and joining the ends, short of their extremities, adjacent the mid-point of one of the sides of the rectangle as shown in Fig. 3. Those portions 12 of the strip between the extremities and the juncture point are provided with notches 14 in the edges thereof. Each notch has a horizontal edge 16, a vertical edge 18 extending downward from one end of the horizontal edge, and a third edge 29 extending at the other end of the vertical edge and disposed at an angle of approximately with the vertical edge so that the three-sided notch is irregular in shape. The outer edges of the sides 22 of the frame, adjacent to the side 24 containing the juncture point of the two end portions, are flared for the more convenient reception of electrical conductors. The other or top side 26 of the frame is provided with an aperture 28 for the reception of a clamp screw 62 to be described later. The inner or confronting surfaces of the sides 22 are provided with threads 29 that cooperate with the clamp screw. The primary function of the frame member in the connector is to receive the various electrical conductors therein and to form a support against which they may be compressed mechanically by the clamp screw so as to afford efiicient and complete current flow.

The frame member is supported in upright position, that is preferably with the longer sides 22 of the frame vertical, on an anchor member 30 composed of an insulating material such as laminated Bakelite or the like in the form of an elongated strip. Spaced at equal distances longitudinally on the under side of the anchor member 30 are circular bores 32 extending about one-half the thickness of the anchor member. These bores or openings receive the locking member to be described in detail later. Located on the upper surface of the anchor member in axial alignment with the circular bores are rectangular slots 36, the long dimension of which is equal to the diameter of the circular bore. The slots 36 in combination with the bores 32 insure that an unobstructed passageway is formed in the anchor member. The frame member and the anchor member are assembled by placing the notched extremities of the frame member into the rectangular slot so that the under surface of side 24 is in contact with the upper surface 38 of the anchor member. The notches 14 in the extended portions of the frame member then at least partially project into the region defined by the circular bore. To maintain the frame member in the anchor member a circular locking member 4% is provided. The locking member is preferably metallic with a diameter slightly less than the circular bore 32 in the underside of the anchor member, insuring a snug fit when the lock member is placed in the bore. The lock member has an upright annular flange 42 around the periphery thereof. Diametrically opposed recesses 44 are provided in the flange for the reception of a tool capable of providing rotary movement to the locking member. Disposed centrally of the locking member is a rectangular slot 46 of the same dimensions of the slot in the upper surface of the anchor member. The

sides

48 and 56 of the rectangular iocking member slot 46 contain oppositely disposed cut-out segments 52 therein. Each segment has an arcuate edge 54 terminating in a shoulder 56. After the frame member has been inserted in the anchor member, the locking member is placed in the circular bore 32 with the rectangular slot 46 in alignment with the rectangular slot 36 in the anchor member so that the extended portion of the frame member projects alsobeyond the locking member. The looking member is then rotatedf90 causing the edges of the cut-outsegments to. cam upwardly. on theuangular edges therein separating the various frame members from .one

another. The end portion of the anchor block may have acircular opening 60 extending through the block for the reception of a rivet orbolt'in. order to fasten the anchor block to a support or panel. A counterhore 61 isprovided to accommodate the head of the rivet or bolt.

Inorder to insure amechanical and electrical connection between conductors placedi-n the frame, a clamp screw62 is provided. The clamp screwispreferably equipped with aconv-entional Phillips head, the under side of which contains serrations 64 in the form of-radial slots, a threaded portion .63, and aportion 65 of reduced diameter. The clamp screw engagesthe threads on the inner confronting su aces of the frame'member as above mentioned. To maintain the clamp screw-62 in engagement with the frame at all times, a Ll-shaped capmember 66 is provided. The cap member contains in-the'two parallel legs 63, 7t), and near the extremities thereof, openings 72 for the reception of a shoe member to be later described. in the side 74 of the U-shaped cap member an aperture 76 is disposed. Also located in the ide 7d are two parallel slots 78, tangential to the aperture 76 and terminating in the legs 68 and 70. The parallel slots and aperture define two oppositely disposed locking tongues 80 upstrucl: from the remainder of cap member 66 as shown in Fig. 4. The tongues have at their unattached extremities a curvature as determined by the curvature of the aperture 76, and are longitudinally twisted in opposite directions and upstruck from the surface of the cap member-so that each makes an angle with the side 7 4 of the cap member that is supplementary to the angle made by the other. In effect the'tongues form a continuation of a helix which is complementary to that on the thread of the clamp screw.

To attain a firm bond between the conductors and the frame member it is necessary toapply, over as great an area of conductors as possible, a constant pressure. Therefore a shoe member 82 of particular configuration is provided across the open end of the U-shaped cap member and extending through the frame. The shoe is formed from a metallic strip and may be considered as composed of two different portions. The first or conductor-engaging portion 84 is bowed so that the under surface thereof acquires a concave or arcuate configuration. The specific type of configuration may be varied depending upon the type and numbers of conductors to be accommodated in the connector. The particular part of the shoe member that lies within the frame member, and this may be considered the approximate middle third part of the shoe member 32, has a length approximately equal to the width of the frame. The other portions of member 32 that overhang the frame are considerably wider so. that not only the bared ends of the conductors are engaged by the shoe but also that part of the conductors that is protected by the insulation is also engaged. These latter portions contain grooves 85 in the conductor- .engat'ing surface so that :1 firm bond between conductor and shoe is il T his arrangement insures a greater resistance to te .sendi forces that act on the conductor as it is flexed when disposed in the connector. This greater resistance to bending enables the connector to be utilized in applications where space is a prime consideration and the conductors of necessity are required to be flexed. ln effect it allows the conductors to be bent around the corners of the connector more readily than in ihe where the current bearing portionof the conductor alone is engaged by aclamping element. This greatcrresistance to the bending forcesdue to flexing offers a further advantage in the prolonged expected use of the conductor before mechanical failure is encountered. At each end of shoe member 82 is a portion 86 adapted to be bent back to overlie portion 84, and each portion 36 has a lug 88, lugs 88 being adapted to enter openings 72 in the cap member asshown for example in Fig. 9.

in assembling the clamp screw, cap member and shoe member, the clamp-screw -is first introduced into the cap member byinserting itin the aperture between the upstruck locking-tongues until the serrations "on the under side of the screw head engage/thelocking tongues. After the serrations move-overxthe inclinedtonguethey will, upon reverse, rotationalmovement, engage or. abut against the elevated side of-the inclined locking tongue and resist such reverse rotational movement. Thereafter the clamp scren and cap member move as a unit with the former extending about .632 inch below the cap member legs 68,

The clamp screw isthen. threaded through the aperture 28 in the frame so, that movement of. the-screw causes the legs 68, 7b of the cap member totbe moved downwardly over the openings inthe .framemember. Before the cap and screw members reach the limit .of their downward travel, the shoe member is inserted through the opening in the frame member. The portions 36 are then bent back over portion 84 and lugs 88 are inserted into openings 72 in the legs-63, 79 as previouslydescribed so that the clamp. screw-directly engagesthe shoe member. The shoe member, however, engages the cap member only in the openings 72, clearing the lowerextremities of legs and if; by about .032 inch, as pointed out-above. This feature is very importantin that it allows the shoe memher to be rockably mounted in the capmember and therefore free to accommodate conductors. of difierent sizes placed inthe :connector from opposite directions. For illustration, assume a #l4wire is inserted in the frame member and a-ir12 wire is'inscrted in the oppositedirection. Formerly when the conductor engaging element was rigidly attached'to the clamp screw, the:larger wire only would receive a firm clamping action and the possibility always existedthat thc smaller wire-would come free. Under the proposed arrangement as outlined above where the conductor-engagingelementuis capable of a rocking action, constant clamping pressure may be applied on different size conductors accommodated in the frame. in practice, it has been found that when two-or more condoctors are insertedin the frame, the overhanging portions of the shoe member initially engage the insulation on the conductors. In responseto additional movement of the screw member, the middle portion of the;shoe.memher tends to flex and contact. the bared ends of the conductors located inthe frame, insuring a firm mechanical bond between the wires and the conductors. As the screw member, cap member and shoe member ,are moved further downwardly on the framemember, by rotation of the screw member, into firm engagement with the electrical conductors previously-inserted in the frame, additional rotational force applied to the screw is transmitted through the head of the screw to the locking tongues'in thecap member. This additional force applied after the shoe member has engaged the conductors tends to movethe upstruck locking tongues, fulcrumed int-he parallel legs of the U-shaped cap member, inwardly into firm engagement with the reduced shank portion of ,the screw,'insuring a positive lock between the cap member and screw member.

An insulation jacket 96 containing three openings 92, 94 and 9-5 is provided for use with the connector. The. circular opening 92- in the top of the jacketallows access to the clamp screw while. the'other openings 94 and .96 are aligned so that the conductors may be placed in the connector. The. jacket is ofuniforrn width but varies as to length so as to afford greaterprotection against shock hazard. Assuming thevertical dimension of the jacket is divided into three equal parts, the uppermost third is about as long as the width of the jacket and embraces the upper part of the connector, the lowermost third is considerably longer, extending out from the connector in two opposite directions so that any bared conductor wires that might possibly extend out of the frame in the connector will be enclosed by the jacket. The middle third varies in length from the length of the uppermost third to the length of the lowermost third. Extending across the of the openings 94 and 96 is a lip 98 adapted to abut against the vertical side of the anchor block when the sides of the jacket are inserted in the indentations 58. Each indentation may accommodate the two adjoining sides of ad acent jackets. After the conductors have been inserted into the insulated connector and clamped therein, lip 98 prevents removal of the insulating jacket from the connector. The insulating jacket is preferably molded from a thermoplastic material but may be composed of any of the conventional insulation materials used in field installations of this type. In some applications of th" mproved connector the insulating jacket may not he required. in such cases a barrier comprising a rectangular shaped strip Bakelite may be inserted in the indentations 58. Additional insulation in the form of a resin idler ion or the like is placed in the bore 32 and allowed to form around the locking member and that portion of the frame member protruding into the bore. This filler serves to protect these parts of the connector from dirt and foreign matter as well as insuring against shock hazard. The filler also prevents rotation of the locking member in the bore.

When it is desired to use the assembled connector in practice, the clamp screw is moved upward in the frame, moving in unison the cap member and shoe member therewith a distance sufiicient to insert two or more conductors from a. plurality of different directions. This multi-directional approach for the conductors is made possible because the conductors may enter the frame member of the connector at an angle due to the flared sides on the frame and the wide portion of the shoe member located outside of the frame, as pointed out above.

Since numerous changes may be made in the abovedescribed constructions, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description as shown in the accompanying drawing shall be interpreted as illustrative and not in a limited sense.

What is claimed:

1. An electric connector comprising a frame having side walls and end portions, one of said end portions having an aperture therein; a screw movably mounted in said aperture; a conductor engaging shoe, defining with said side walls and one of the end portions of said frame a conductor accommodating opening, said shoe having enlarged end portions and a central portion assembled with said frame so that the end portions protrude beyond the frame opening, lugs at the extremities of said enlarged end portions, said lugs being bent back so as to partially overlie said enlarged sections; and a U-shaped cap movably mounted on said frame with the parallel legs thereof having aligned openings therein for the reception of said lugs, said cap including an opening in the portion connecting the parallel legs for the reception of said screw, means for preventing disassembly of said cap and said screw whereby relative movement of said screw and said shoe is prevented.

2. In an electric connector the combination comprising a frame formed from a strip resilient metallic material shaped so as to define a generally rectangular opening having opposed side walls and end portions, the ends of said strip extending normal to the midpoint of one of said end portions in a confronting relation so as to form a flange, said flange having notches in the opposed edges thereof, means for clamping conductors in said opening against an end portion of said frame, a frame support having a passageway therein to accommodate said flange and a circular recess forming an extension of said passageway, and a lock washer within said circular recess, said lock washer having a generally rectangular opening, the longer sides of which include diametrically opposed cut out portions terminating in shoulders, said lock washer being so positioned Within said recess so that the frame may be inserted through both the passageway and the opening in said lock washer with the notches in the edges of said frame flange in engagement with the washer opening whereby the frame may be locked to said support upon rotation of said washer.

3. An electric connector comprising a frame member having opposed side walls and end portions, a conductor engaging shoe movably mounted within said frame, said shoe defining with the side walls and one of the end portions of said frame a conductor accommodating opening, said shoe including enlarged portions protruding from said frame and lugs at the extremities of the projecting portions, a screw movably mounted in said frame and a U-shaped cap mounted on said frame so that the parallel sides thereof enclose said frame opening, said cap including an aperture in one side thereof for the reception of said screw and oppositely disposed openings in the parallel sides thereof for the reception of said lugs, said last mentioned openings being greater in area than the cross sectional area of said lugs so that limited rotational movement of the shoe relative to the cap is permissible.

4. An electric connector comprising a screw having a threaded portion defining a helix and an unthreaded portion of smaller diameter than said threaded portion, an open-sided frame adapted to receive a plurality of electric conductors therein and containing an opening in one end thereof, means for mounting said frame on a supporting block, a U-shaped cap having first and second parallel legs and a central portion connecting said legs and containing a central aperture, first and second locking tongues struck from said frame adjacent to said aperture, the free ends of said tongues at least partially forming the periphery of said aperture, the free ends being twisted relative to the surface of said central portion to define a helix complementary to the helix defined by the threads of said screw, and a shoe including a central conductor-engaging portion and first and second capengaging portions at the extremities of said conductor-engaging portion, the unthreaded portion of said screw being located in said aperture and said threaded portion passing through said opening, so that said legs overlie the open sides of said frame and the conductor-engaging portion of said shoe is positioned to be engaged by the end of said screw and the cap-engaging portions of said shoe engage said legs.

References Cited in the file of this patent UNITED STATES PATENTS 582,464 Dusenbury May 11, 1897 1,437,209 Wenderhold Nov. 28, 1922 1,514,928 Rabezzana Nov. 11, 1924 2,205,322 Thomas, Jr. et al June 18, 1940 2,239,100 Jackson Apr. 22, 1941 2,263,319 Treanor Nov. 18, 1941 2,287,762 Rogoff June 23, 1942 2,364,846 Hartman Dec. 12, 1944 2,371,446 Jensen Mar. 13, 1945 2,401,130 Ayres May 28, 1946 2,542,084 Hrach Feb. 20, 1951 2,636,065 Fiske Apr. 12, 1953 2,693,587 Davidson Nov. 2, 1954 FOREIGN PATENTS 678,912 Germany July 25, 1939 888,909 France Dec. 27, 1943 893,118 France Ian. 17, 1944 905,493 France Dec. 5, 1945