US 3377611 A
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Description (OCR text may contain errors)
W. S. PAWL April 9, 1968 RIGID PARALLEL SIDED SQUEEZE SLOT CONNECTOR Original Filed March 19, 1965 2 Sheets-Sheet 1 w. s. PAWL 3,377,611
RIGID PARALLEL SIDED SQUEEZE SLOT CONNECTOR April 9, 1968 2 Sheets-Sheet 2 Original Filed March 19, 1965 INVENTOR United States Patent 9 3,377,611 RIGID PARALLEL SIDED SQUEEZE SLOT. CONNECTOR Walter S. Pawl, 2844 .Powde'r Mill Road, Adelphi, Md. 20783 Continuation of application Ser. No. 441,780, Mar. 19, 1965. This application Dec. 12, 1966, Ser. No. 601,209 The'portion of the term f the patent subseq'uent to May 11, 1982;, hasbeen disclaimed 9 Claims. (Cl. 339 97) ABSTRACT OF THE- DISCLOSURE The present invention comprises a solderless, rigid, electrical connector plate of a thickness substantially greater than the diameter of a wire to be received in a parallel sided slot therein, having a width smaller than said diameter, through a flared end portion of said slot sides, so that the wire is compressed as itis forced into said slot to maintain a good pressure contact therein which provides a reliable electrical connection with said plate and therethrough with any other wire connected to said platein the same or another slot in the plate, the plate being either fiat or any other shape, including curved and cylindrical shapes.
This application is a continuation of Ser. No. 441,780, filed Mar. 19, 1965, and now abandoned.
This invention relates to improvements in simple wire connector units of the type illustrated in my copending application Ser. No. 313,282, filed Oct. 2, 1963, now Patent No. 3,183,472, for Unitary Rigid Wire Connectors and Method of Making Wire Connections.
The object of this invention is to make a simple rigid conducting connector element having a smooth-sided slot of constant width, said smooth sides being flared at the open end of the slot for squeezing and receiving a plurality of squeezed wires pushed into said slot through the flared open end while breaking through their insulations (if any) to provide high pressure contacts between the element and each wire.
A further object is to arrange this slot advantageously on various forms of supporting structure to strengthen its rigidity and add to its capacity with minimum dimensional increase while maintaining simplicity, reliability and'ease of operation.
A further object is to provide an insulator block around this connector, of simple form having a recess .for the open ends of the wires and a guide slot for the lead ends thereof.
A further object is to provide a closure cap of insulating material to close said recess and hold said wires in said connector, where protection from the elements or shock proof reliability is desirable.
A further object is to provide a waterproof seal between said block and said closure cap for underwater or field use in wet surroundings.
Other and more specific objects will become apparent in the following detailed description of some forms of connectors made in accordance with the present invention as illustrated in the accompanying drawings, wherein:
FIG. 1 is an enlarged end elevational View of an insulated block form of connector units indicating how additional units may be formed in a continuous block of insulating material to provide a compact multi-terminal connector block, i
FIG. 2 is an elevational sectional view of .this form of connector unit taken axially through the slot,
FIG. 3 is a similar sectional view of a modification having a pocket and a closure at the back of the slot, and showing a sealing cap that may be used to provide a FIG. 6 is a sectional view of a modification of the novel parallel slot connector, taken on the line 6'-6 of FIG. 7, FIG. 7 is a sectional view of'this' modification taken on the line 7-7 of FIG. 6,
FIG. 8 is a similar sectional view of a modified closed back type of insulating block which may be used with this formof connector, showing a snap-on cap of insulating material,
FIG. 9 illustrates a wire inserting of the various forms of slotted connectors,
FIG. 10 is a partial end view of a circular block form of connectors having a plurality of inwardly open slotted connector elements insulated from each other, I
FIG. 11 is a similar circular block form having a cylindrical enclosure at the back of this block with radial com partments back of the slotted connectors to accommodate the loose ends of the wires in each slot,
FIG. 12 is a perspective view of a connector plate element having opposed internally opening slots,
FIG. 13 is a perspective view of another form of connector plate element having a single slot internally open at both ends,
FIG. 14 is a perspective view of an insulated, cylindrical connector having opposed internally open slots in its side,
FIG. 15 is another cylindrical connectoropen at one end and having two slots in its sides extending axially from the open end.
FIG. 16- is another cylindrical connector open at both ends and having a slot in its sides extending axially from each open end, and another circumferentially extending slot in its side, and
FIG. 17 shows a double slotted connector element in perspective and a possible insulator block form that may be used therewith. l
The basic invention comprises a rigid slotted structure with conductive material extending at least along one side of the slot, said structure being of hard material having a higher limit of elasticity in compression than conventional wire materials, the slot having smooth parallel sides flared at the entrance to receive and compress wires of larger diameter than the spacing of said parallel sides, as they are forced through said flared entrance into the slot. The rigidity of the structure, which may simply be a slotted plate of conductive material of suitable thickness, is suflicient to result in insignificant strain when the sides are subjected to the wedging of the wires as they are inserted and held under compression between the sides of the slot which therefore remain substantially parallel. There is thus no tendency for the wires to creep out of the slot as a result of continuous vibrations, or to loosen when moved to ditferent positions in the slot. In conventional slotted connectors, the wires have a tendency to creep along the slot because the sides of the slot are not or do not remain parallel after insertion of the wires. Some lock means have to be used toprevent such creeping or loosening, as e.g. in the Levin et al. Pat'- ent No. 3,012,219.
In other known slotted connectors, means are provided to score or cut into the sides of the wire to reduce it to the size of the slot, as e.g. in the Miller Patent No. 2,333,266. This obviously weakens the wire and relieves any pressure of compression at the contacts.
The present improved rigid connector element, having a smooth-sided slot in which the sides are parallel except at the entrance where they are flared to receive and smoothly compress the wires into the slot without scoring, does not weaken the wires, since the cros s-secof he tool for use with any tional area of the compressed wire is not reduced but merely flattened at the contacts with the smooth sides of the slot, and the wire is held under the high pressure of compression. The maximum pull-out strength of the wires in the connector is thus preserved.
The pressure of compression at these contacts is ob viously of the order or close to the elastic limit of the wire material, if the wire has received any permanent deformation, so that even if it should become necessary to remove it from the slot for any reason, and it is then again reinserted in the same slot where it was before, substantially the same high pressure of compression at the contacts would be regained, and the same creep resistance would be attained, because the structure and strength of the connector material is sufficient to maintain substantial rigidity even under maximum wedging stresses in normal use.
A different size slot is used for different ranges of wire sizes, but it was found that one size slot could be used conveniently for three or four consecutively larger sizes of wires. For example, sizes No. 16 to No. 12 could be used in a standard size slot which, has its parallel sides spaced slightly less than the diameter of the No. 16 wire.
The structure forming this connector slot need not be a flat conductor plate, but the plate may be curved as in the cylindrical connectors shown with externally or internally opened slots extending axially of the cylinder or internally opened slots extending circumferentially of the cylinder.
The structure forming the slots need not be a plate at all, but may include a pair of pins of hard conductive material held rigidily in spaced-apart parallel relation to form the smooth sides of the slot and having roundly tapering outer points to form the flaring entrance to the slot. These pins may be firmly set into the bottom and along the opposite sides of a guide groove formed in the guide slot of an insulator block which provides suitable rigidity to the connector structure to prevent spreading of the pins under extreme wire wedging stresses. Obviously, only one of the pins or sides of the connector slot need be of conductive material to provide the electrical flow of current between 'all the wires in the connector slot.
Referring to the illustrated forms of connector elements and insulator blocks, FIG. 1 shows a rectangular insulator block 20 having a guide slot 27 fonthe wires 31 to each side of a standard connector element 23 inserted into a corresponding dimensioned slot 29 in the block 20 and firmly fixed therein. The connector element 23 has a smooth parallel-sided slot 22 aligned with the guide slot 27; however, the sides of slot 22 apart a distance slightly less than the diameter of the smallest size wire in the range of sizes which this connector is adapted to accommodate. Any suitable hard conductive material, such as hard Phosphor bronze, may be used, and the smooth sides of the slot may be suitably flared at the open end of the slot and be narrowed to a point at to provide a means for breaking into the insulation 24 (if any) to facilitate its separation at the contacts as the wire is pushed down into the slot. The pushing may be done by an instrument of the type shown having a guide knob '50 or 60 at the outer end of a vertical blade 52 or 62 with a common V groove in their lower edge 54 or 64 respectively for placing axially over the wire to be pushed into the slots. These blades 52 and 62 may be made for use with two different sizes of connectors used for different size ranges of Wires. These blades are formed as jaws in a plier type tool as shown in FIG. 9, having handles 56 of any suitable length and shape as may be desired. To use this tool the groove of the proper size blade is placed over the wire to be pushed into the connector slot as shown in dotted lines in section in FIG. 10, the other jaw being placed under the connector, the knobs being positioned approximately in line with the plane of the slot and just beyond its far end, as indicated in dotted lines in FIG. 2. In this posiare spaced tion the handles 56 'are pressed together to push the wires into place in the connector slot, the smooth sides of which shear a strip of the insulation off the adjacent surfaces of the wire which brings the bare wire into a squeezing contact with the smooth sides of the slot as it slides through their flared portions intothe slot. The sheared portion of the insulation which tends to cling to the remaining insulation and is packed down or remains loose around the joint, serves to retard corrosion and oxidation around and at the joint along with the seal already formed by the sheared off edges of the insulation all around the contact points.
It is to be noted that the contactareas between the sides of the slot and the surface on opposite sides of a wire will vary in width depending on the difference be tween the size of the slot and the wire, but even if this is a minimum, approaching a mere line contact, the unit pressure of compression is just as high if any permane'nt flattening of the wire occurs,
which effects its resistance is substantially zero.
The knobs and are made of a size to correspond with the size of guide slots 27 inthe corresponding size insulation blocks, so that they will serve to guide the blade 52 and 62 respectively over the center of the wire.
Feet 26 may be provided at the base corners of the block 20 for mounting in any forms of slide mounting strips or brackets on a wall or panel. The blocks may be extended as shown 'at ,21 in FIG. 1 to form a plurality of connectors in one block.
The blocks may be open at both ends of the guide slot 27, as shown in FIGS. 1 and 2, so that wires may come in from either side of the block, or they may be closed at the back as shown in FIG. '3, so that all .wires come in from the front end. In either type of block, a simple cap 32 of insulating material may top of the block by providing a series of bumps 36 and 38, and corresponding depressions 37 and 42 as shown inside the front and rear flaps and at corresponding int tervals on the front and back of the block. These caps 32 could be extruded channelstrips cut in any lengths in accordance with the number of connectors in a block. Where water tight sealing is required, sealing strips 34 of soft rubber or similar resilient material could be fixed inside the cap around the lower edge of the front flap, the end edges, and the upper or lower edge of the rear flap, depending on whether the block is closed or open at the back respectively. Where the block is open, the soft sealing strip has to be at the lower edge to provide a good seal over the top of the wires extending from the guide slot.
In the form of block 28 which has a closed back 30, no guide slot 27 is needed for the loose ends of the wires,
and this slot back of the connector element 23 may be widened and deepened into a pocket as shown in FIGS.
3 and 4 to provide ample room for longer loose ends,
which may be bent within the pocket 33 to further increase their pull-out strength. A multiple connector block of this form is shownin FIG. 4 having large pockets33 for the loose ends of the wires.
Another form of multiple connectormay have a disc.
type of insulator block as shown partially in FIG. 10,
where the standard flat plate connector elements may be radially spaced to open internally into a central openir'rg in the block. This provides maximum rigidity against high bending moments on the sides of the slots due to.
high loading stresses, thus permitting the use of thinner plate material for the connector elements without danger of distorting the slot sides from their parallel spacing.
because the elastic limit of compression will have been surpassed before the peri be fitted to snap over the i The-connector 88 shown in FIG.- comprises an insulator disc 98'open at the-center and having four radially extending guide slots 106 opening inwardly and being spaced'90" apart. The four connector elements 90 are firmly embedded in radial pockets in the disc with the connector slots 92 aligned with the guided slots106. Two wires 94 and 96 are shown inserted in the lower connector.
A further modification of a'similar radial arrangement of'eight standard connector elements 102 is shown in FIG.'11,' in the insulatordisc 100 which'in this case, however, is formed integrally with a cylindrical enclosure 138 extending from the back of the disc. This enclosure is compartmentized by radial partitions 140 to provide separate pockets for the loose ends of wires mounted in each connector element, in order to keep the wires from accidentally shorting between connectors.
The connector element instead of having a slot open at the edge of a flat plate, may have internally opening slots, open at one'end only as slots 116 in FIG. 12 or open at both ends as slot 122 inFIG; 13 .The openings 120 and 114 in the plates 118 and 112 respectively, at the entrances to the internally openingslots are large enough to pass the knobs of the corresponding tool jaws for use with these connectors. The flared open ends of the slots are shown at-124 and 113. For insulation these plates with the joined wires extending from one side of the plate may be capped by an insulator over the loose ends of the wires and having a skirt extending over the other side of the plate.
The connector element may further be curved as in the cylindrical forms shown in FIGS. 14 to 16, and here again, the slots may open externally at an outer edge as slots 136 in FIG. 15, and slots 144 and 146 in the cylinder 142 of FIG. 16, or they may open internally as slots 128 into the large opening 130 in FIG. 14, and peripherally extending slot 147 into the large opening 148 in FIG. 16.
An insulator cylinder 126 with closed ends 132 may be used for the connector as shown in FIG. 14. A cap 134 closed at one end only to insulate the cylindrical connector element as shown in FIG. 15, or an open ended insulator sleeve may be used on a cylindrical connector element as shown in FIG. 16. The open ends of the cylindrical insulator sleeve or caps may extend beyond the ends of the respective connector elements to serve as a protective skirt to prevent accidental shorts or contact with unshielded or grounded conductors in junction boxes or the like.
FIG. 17 illustrates a U-shaped plate connector element 80 having a pair of aligned connector slots in the legs of the U. The element 80 is mounted in a rectangular insulator block 86 with its guide slots 84 lined up with the connector slots and having a pocket back of the connector element .for the loose ends of the wires as in the block shown in FIG. 4.
The connector element need not be of plate form at all. It may comprise a pair of smooth cylindrical pins mounted rigidly in spaced parallel relation to form the connector slot as shown in FIGS. 6 to 8. The pins 68 are mounted rigidly in bores 70 in the bottom of the guide slot of an insulator block 66, on opposite sides of the slot, the bore extending partially into the sides of the slot to form grooves 72 therein against which the pins are firmly braced, to provide them with the necessary rigidity and strength against deformation of the parallel slot sides formed by the pins when placed under stress by insertion of the wires.
The pins 68 are roundly tapered to a point at the top to provide the flared entrance for receiving and squeezing the wires into the connector slot between them, and the points at their tops provide a means for initiating the breaks in some of the tougher insulations to facilitate the shearing thereof at the points of squeezing so as to bring the slot sides into direct surface contact with the bare wire at these points.
6 FIG. 8 shows a modification of the insulator block 74 by adding a closure wall 76 at the back of the guide slot, and the same type of cover.32 may beused on this block as on block 28 of FIG. 3, with the hollows36 and 38 on the inside of the front andrear flaps adaptedto snap over the bumps 40-and 42 respectively on-theoutsideof the block 74. The sealing strip 34 may be used for water tight closure overtwowires in each connector element, as .in FIG. 3.
Obviously, only one side of the connector elementmeed beof conductive material to provide the necessary, connection between the Wires. Thus one pin 68.,may be conductive, the other. may be replaced by'an integralridge of the insulator material of the ,blockextending [from the side of the guide slot opposite the singlepin 68..
Generally, for best results,.the sidesof the..slot should be substantially flat for a.width at. least equal,.to.their spacing, so that the flattening'of. the wire as;v it isv compressed by the sides will cause aminimumof lengthwise distortion of the Wire. and will not materially reduce its cross-sectionalarea, thus preserving substantially its. original tensile or pull-out. strength at the connection,
A hard Phosphor. bronze has been found to beasatisfactory conductive material for the; connector element, but any other. suitable-conductors may be used.
Many other obviousmodificationsmay be. made in the arrangement and details of the several parts without departing from the spirit and scope of the present invention as defined in the appended claims.
What is claimed is:
1. A solderless, rigid, electrical connector element for connecting a plurality of wires together without requiring prestripping, twisting or cutting the wires, comprising a slotted structure of hard material having a smoothly parallel-sided slot with sides spread apart a distance which is less than the diameter of the bare wires to be connected,
said sides being smoothly flared out at least at one open end of the slot and adapted to receive and smoothly compress a wire pushed therethrough while squeezing any insulation on the wire from its bare contact surface with said sides,
at least one of said sides being conductive so as to provide an electrical connection between the wires in said slot,
said sides being flat and preferably at least as wide as their spacing to minimize weakening of the wire by reduction of its cross-sectional area due to any flattening in the axial direction caused by its compression between said sides, and
said slotted structure being a conductor plate of suitable thickness to provide sutficiently wide slot sides, and being curved in cross-section in a plane normal to said slot.
2. A connector element as defined in claim 1, said curved cross-section being a circular annulus.
3. A connector element as defined in claim 1,
said slot opening at an internal edge of an opening in said plate at one end of the slot.
4. A connector element as defined in claim 1,
said slot opening at an internal edge of an opening in said plate at each end of said slot to provide an entrance to either end of the slot so that either of two Wires in the slot may be quickly replaced without disturbing the other.
5. A connector element as defined in claim 3,
said slotted plate structure having a second slot opening at the internal edge of the same opening in the plate, so that wires in either slot may be quickly replaced without disturbing those in the other slot.
6. A solderless, rigid, electrical connector element for connecting a plurality of wires together without requiring prestripping, twisting or cutting the wires, comprising a slotted structure of hard material having a smoothlv parallel-sided slot with sides spaced a distance which is less than the diameter of the bare wires to be connected,
- said sides being smoothly flared out at least at one open end of the slot and adapted to receive and smoothly compress a wire pushed therethrough While squeezing any insulation on the wire from its bare contact surface with said sides,
at least one of said sides being conductive so as to provide an electrical connection between the wires in the slot,
said sides being flat and preferably at least as wide as their spacing to minimize weakening of the wire by reduction of its cross-sectional area due to any fiattening in ,the axial direction caused by its compression between said sides, and
said slotted structure having the slot opening at an external edge of said structure, and
an insulator block in which said element is embedded,
said block having a guide slot alined with the slot in said element extending forwardly thereof adapted to receive and guide the lead-in ends of terminal wires to be connected together, and having a pocket at the rear of said element adapted to receive the loose ends of said wires.
7. A connector element as defined in claim 6, and
a closure cap of insulator material adapted to snap 8 a over the top of the block to protect it from the elements and to hold down the lead-in ends of the wires against possible loosening by extraneous vibrations.
8. A connector element as defined in claim6, and
additional connector elements embedded ina lateral extension of said block to provide amulti-connector block.
9. A connector block combination as defined in claim 8,
said lateral extension being cylindrical, and radial partitions between the connector elements, providing sectorially formed pockets for the loose ends of the wires back of the connector elements opening in wardly.
References Cited 1 UNITED STATES PATENTS 2,333,266 11/1943 Miller 339-95 3,183,472 5/1965 Pawl 339-97 FOREIGN PATENTS 542,852 12/1955 Belgium.
MARVIN A. CHAMPION, Primary Examiner.
EDWARD C. ALLEN, Examiner.
JOSEPH H. MCGLYNN, AssistantExam-iner.