US3812449A

US3812449A - Terminal strip

Info

Publication number: US3812449A
Application number: US00355455A
Authority: US
Inventors: R Elm
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1973-04-30
Filing date: 1973-04-30
Publication date: 1974-05-21
Anticipated expiration: 1991-05-21
Also published as: SE7405290L; FR2227654B3; CH578264A5; BR7403467D0; FR2227654A1; DE2421054A1; ES425522A1; CA995326A; IT1004299B; NL7405380A; AR198596A1; BE814339A; ZA742684B; GB1452639A; JPS5015087A

Abstract

A terminal strip including an elongate block of electrically insulating material divided lengthwise into a plurality of terminal strip sections. Each terminal strip section has a plurality of wire receiving bores and a plurality of contact elements having spaced wire engaging fingers slidably mounted in the block to engage and interconnect wires in adjacent bores of that section. The sections may be supported in an elevated position to afford use of a tool, such as a pliers, to seat a contact element, and the contact element and the block include means which afford disengaging a contact element with a pointed tool such as a screwdriver.

Description

United States Patent [1 1 Elm [111 3,812,449 1 May 21, 1974 1 TERMINAL STRIP {75] Inventor: Robert A. Elm, St. Paul, Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul,

Minn.

221 Filed: Apr. 30, 1973 [21] Appl. No.: 355,455

521 user. 339/98, 339/125R [51 Int.Cl ..H0lr9/08 [58] Field of Search 339/97-99, 339/125 [56] References Cited UNITED STATES PATENTS 3,605,072 9/1971 Driscoll 339/98 3,656,088

4/1972 Seim 339/98 Primary Examiner-Joseph H. McGlynn Attorney, Agent, or Firm-Alexander, Sell, Steldt &

DeLaHunt [5 7] ABSTRACT A terminal strip including an elongate block of electrically insulating material divided lengthwise into a plurality of terminal strip sections. Each terminal strip section has a plurality of wire receiving bores and a plurality of contact elements having spaced wire engaging fingers slidably mounted in the block to engage and interconnect wires in adjacent bores of that section. The sections may be supported in an elevated position to afford use of a tool, such as a pliers, to seat a contact element, and the contact element and the block include means which afford disengaging a contact element with a pointed tool suchas a screwdriver. a

6 Claims, 9 Drawing Figures 7 TERMINAL STRIP BACKGROUND OF THE INVENTION This invention relates to terminal strips for interconnecting separate sets of wires.

Terminal strips are commonly used to electrically interconnect sets of wires. A terminal strip typically includes an elongate block of electrically insulating material adapted to be mounted to a structure and having a plurality of screws in threaded sockets spaced along the block, some of which may be electrically connected. A set of wires is interconnected by connecting one end of each wire to a common screw or to one of a series of electrically connected screws. To make such a connection, insulation must be stripped from the end of the wire. If the wire is solid, the stripped end may then be bent in a U-shape and hooked around a screw, whereas if the wire is stranded a special tip in the form of an eyelet or fork should be engaged with the stripped end and the tip then inserted under the head of the screw. The screw is tightened with a screwdriver to complete the connection. This connection process is tedious and re quires an inordinant amount of time particularly where a large number. of connections must be made and broken as during experimental work or the rewiring of equipment.

While connectors are known which utilize contact elements having spaced resilient fingers defining wire accepting slots to interconnect two or more small gauge wires such as are disclosed in U.S. Pat. Nos. 3,0l2,2l9, 3,388,370, 3,656,088 and 3,609,644, there has heretofore been no known terminal strip which utilizes such contact elements to interconnect separate sets of wires and which is adapted to afford ease of connecting or disconnecting individual wires in a set.

SUMMARY OF THE INVENTION A terminal strip according to the present invention affords efficient interconnection of sets of solid and/or stranded power wires of up to No. AWG by the simple process of positioning the wire in a bore in the terminal strip and pressing a contact element into engagement therewith with a conventional pliers. Additionally, the connection to any one wire can be easily broken by prying the contact element out of engagement with a screwdriver.

According to the present invention there is provided a terminal strip for electrically interconnecting separate sets of wires. The strip includes an elongate block of electrically insulating material divided along its length into a plurality of terminal strip sections. Each terminal strip section has opposite first and second surfaces and a plurality of parallel spaced wire receiving bores through the block between the surfaces. The block has a plurality of sockets, each extending from the first surface transverse of at least two adjacent bores. Each of the sockets slidably receives one of a plurality of contact elements for movement between a disengaged position with wire engaging fingers of the contact element spaced from the bores to afford positioning wires therein, and an engaged position with the fingers across the adjacent bores to engage and interconnect wires therein. Each pair of adjacent bores in each terminal strip section has one of the interconnecting contact elements to afford interconnection between wires in all the bores of onesection.

The terminal strip includes means for mounting the 1 block with the second surface spaced from the mounting structure to afford engagement of the jaws of a pliers on the second surface and one of the contact elements so that the contact element may be pressed toward the second surface to the engaged position. For each socket the connector has a notch along the first surface which intersects the socket and affords access for the tip of a bladed tool such as a screwdriver with a contact element in the engaged position so that the contact element may be pried to the disengaged position to break the electrical interconnection between adjacent wires.

Also, a contact element may be included in the terminal strip which includes a screw or the male tab of a quick connect terminal on the end of the contact element which is exposed along the first surface of the terminal strip when the element is engaged as may be desirable under certain circumstances to afford a more conventional connection to a wire.

BRIEF DESCRIPTION OF THE DRAWING The invention will be further described with reference to the accompanying drawing wherein like numbers refer to like parts in the several views, and wherein:

FIG. I is a perspective view of a terminal strip according to the present invention interconnecting a set of wires in one terminal strip section;

FIG. 2 is an enlarged section taken approximately along the lines 22 of FIG. land illustrating a contact element of the terminal strip being pressed into engagement with a wire via a pliers;

FIG. 3 is an enlarged section taken approximately along the lines 22 of FIG. 1 illustrating the contact element being disengaged from the wire via a screwdriver;

FIG. 4 is an enlarged section taken approximately along the lines 4-4 of FIG. 1;

FIG. 5 is an enlarged section taken approximately along the lines 5-5 of FIG. 1;

FIG. 6 is an enlarged perspective view of a first embodiment of the contact element used in the terminal strip of FIG. 1; I

FIG. 7 is a perspective view of a second embodiment of a contact element for use in the terminal strip of FIG. 1;

FIG. 8 is a perspective view of a third embodiment of a contact element for use in the terminal strip of FIG. I; and

FIG. 9 is a perspective view of a fourth embodiment of a contact element for use in the terminal strip of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 of the drawing there is illustrated a terminal strip according to the present invention generally designated by the numeral 10. The terminal strip 10 includes an elongate block of electrically insulating material such as polypropylene, divided along its length into a plurality of terminal strip sections 12 (illustrated as three). Each terminal strip section 12 has a plurality of sockets l3 shaped to slidably receive conductive contact elements 14 adapted to interconnec't wires 16 inserted into parallel bores 18 therein.

The terminal strip sections 12 are rectangular, each having a first surface through which the contact elements 14 are mounted, an opposite second surface 22, and opposed end surfaces 24. The sections 12 are sepa rated by projecting flanges 26 to restrict arcing or accidental shorting between the exposed contact elements 14. Each section 12 has four wire receiving bores 18 in communication between the end surfaces 24 which are equally spaced and axially parallel, and are positioned midway between the first and

second surfaces

20 and 22.

. Each terminal strip section 12 also has three of the sockets 13 spaced axially along the bores 18, with each socket 13 intersecting two separate adjacent bores 18 at a right angle to the axis thereof, and communicating between the first surface 20 and the two bores 18 which it intersects. Each socket l3 slidably receives one of the contact elements 14 for movement between a disengaged position projecting above the first surface 20 (see the contact elements 14 in the central terminal strip section 12 of FIG. 1 as illustrated) with wire engaging fingers 30 on the contact element 14 spaced from the two intersected bores 18 to afford the insertion of wires therein; and an inserted engaged position -(see the contact elements 14 in the left end terminal 16 in any two adjacent bores 18 can be interconnected by one of the contact elements 14, and up to four wires 16 may be interconnected in each terminal strip section 12 so long as a bore 18 between wires 16 to be interconnected is not left empty. Alternatively, interconnections between two separate sets of two wires can be made in each terminal strip section 12 by leaving the central contact element 14 in the disengaged position.

The elongate block has end mounting brackets 32 with feet 34 each having a central notch 36 adapted for receiving a screw to attach the terminal strip 10 to a mounting structure. The mounting brackets 32 space the terminal sections 12 away from a structure on which they are mounted and position the first and

second surfaces

20 and 22 at about a 30 angle thereto. This allows a craftsman to conveniently use a pliers 38 to press one of the contact elements 14 from the disengaged to the engaged position by engaging one jaw of the pliers with the second surface'22 and the opposite jaw with the upper edge of the contact element 14 exposed along the first surface 20 (FIG. 2).

Each contact element 14(FIG. 6) is a conductive f silient metal plate-like member having the spaced fingers 30. The fingers 30 define two wire accepting slots 40 therebetween adapted for forceful entry of a wire segment under a force sufficient to resiliently separate the fingers 30, thereby forming a positive electrical connection with the wire. The ends of the fingers 30 are radiused to aidin spreading the fingers 30 and guiding a wire into the slots 40, and the contact element has a relief slot 42 between the inner two fingers 30 to afford proper flexure thereof. As pressure is applied to force wires into the slots 40, the ends of the fingers first penetrate any insulative covering on the wires, and eventually partially deform the engaged wire segment. At the same time, the resilient fingers 30 are forced apart and thus apply a continual pressure against the conductor to maintain a positive electrical connection.

As is best seen in FIG. 5, the block includes a pair of transversely extending thin bars 43 in each socket 13 aligned with the bores 18 intersected by the socket 13 and each having anupper edge aligned with the wall of the adjacent bore 18 on the side opposite the first surface 20. The bars 43 in each socket 13 are positioned and are sufficiently thin to enter the wire accepting slots 40 of a contact element 14 moved to the engaged position in that socket 13 without deflecting its fingers 30. The upper edge of each bar 43 provides means for supporting the segment of a wire in the adjacent bore 18 which will be forced between the fingers 30 as the contact element 14 is moved to the engaged position.

The terminal strip 10 also includes means for affording movement of the contact elements 14 from the engaged to the disengaged position via the use of a screwdriver 44as is illustrated in H0. 3. The-contact element 14 (illustrated most clearly in FIG. 6) has an elongated opening 45 extending parallel to and adjacent its end opposite the fingers 30. When the contact element 14 is in the engaged position, the opening 45 is aligned with the bottom of a notch 46 along the first surface 20 of the terminal strip section 12, which notch 46 is tapered in depth and intersects the socket 13. The tip of the screwdriver 44 may be inserted through the notch 46 and into the opening 45, and pivoted against the first surface 20 to pry the contact element 14 from the engaged to the disengaged position.

Although this invention is subject to considerable variation without departure from the spirit thereof it is believed that the following specific example, adapted to interconnect wires of from No. l8 AWG to No. 14 AWG, will facilitate understanding: Each terminal strip section 12 is about 1 inch deep between the end surfaces 24, 0.4 inch thick between the first and

second surfaces

20 and 22, and 0.7 inch wide between the flanges 26. The four bores 18 are about 0.14 inch in diameter and spaced on 0.18 inch centers. The end brackets 32 support the first and

second surfaces

20 and 22 at an angle of about 30 with a surface on which the terminal strip is mounted, with the edge of the secend surface 22 furthest from the mounting surface being spaced about 0.85 inch therefrom. The contact element 14 is 0.036 inch thick and made of tin plated spring tempered cartridge brass. The fingers 30 are about 0.17 inch long, 0.06 inch wide, and the width of the wire accepting slots 40 is about 0.025 inch.

FIG. 7 illustrates a second embodiment of a contact element adapted for use in the terminal strip and generally designated by the numeral 48. The contact element 48 has fingers 50,.two wire accepting slots 52 and a central relief slot 54 which are essentially identical to the same portions of the contact element 14, the only significant difference being that instead of the elongate opening 45, the contact element 48 has a tab 56 projecting at right angles from its edge opposite the fingers 50. The contact element 48 is positioned in its receiving socket 13 so that the tab 56 projects over the notch 46. When the contact element 48 is in the engaged position, the tip of a screwdriver may be inserted in the notch 46 between the firstsurface 20 and the tab 56 to pry the contact element 48 to the disengaged position.

FIG. 8 illustrates a third embodiment of a contact element adapted for use in the terminal strip and generally designated by the numeral 60. The contact element 60 has fingers 61, two wire accepting slots 62, a central relief slot 63 and an elongate opening 64 adapted to receive the tip of a screwdriver which are essentially identical to the corresponding portions of the contact element 14. The contact element 60 has a protrusion 65 projecting at right angles from its end opposite the fingers 61 and having a generally central tapped hole adapted to receive a conventional screw 66. The contact element 60 is positioned in its receiving socket 13 so that tab 56 projects over the first surface away from the notch 46 with the screw 66 projecting at a right angle away from the first surface 20. A wire may be interconnected with wires engaged by the contact element 60 in the bores 18 by attaching an end of the wire under the screw 66 in the conventional manner.

FIG. 9 illustrates a fourth embodiment of a contact element adapted for use in the terminal strip and generally designated by the numeral 70. The contact element 70 has a tab 71 which is the male tab portion of a quick connect terminal according to N.E.M.A. Standard 7-15-1970. When the contact element 70 is in the engaged position the tab 71 is positioned to project from the first surface 20 of the terminal strip to afford engagement with the female. connector of the quick connect terminal to interconnect a wire with wires in the bores 18.

A first planar portion of the contact element 70 has fingers 72, two wire accepting slots 73, a central relief slot 74 and an elongate opening 75 transverse of its end opposite the fingers 72 adapted to receive the tip of a screwdriver which are essentially identical to the corresponding portions of the contact element 14. The contact element 70 also has a generally L-shaped extension from the end of the planar portion opposite the fingers 72 including a normally extending portion 76, and the tab 71 which extends parallel to and in an opposite direction than the planar portion from the end of the portion 76 opposite the planar portion. The contact element is positioned in its receiving socket 13 so that the portion projects over the first surface away from the notch 46. Thus the portion 76 is positioned for engagement by the jaw of a pliers to press the contact element 70 to the engaged position, and the tab 71 projects from the first surface 20 to afford an electrical connection therewith.

I claim:

1. A terminal for electrically interconnecting sets of wires, comprising:

a plurality of resilient conductive contact elements each having spaced fingers defining at least two wire accepting slots therebetween adapted for forceful entry of a wire segment under a force sufficient to resiliently separate said fingers to form a positive electrical connection with the wire;

a block of insulating material defining a plurality of terminal sections each having opposite first and second surfaces, a plurality of spaced bores in the block between said surfaces each adapted to receive a said wire, and a plurality of sockets extending from said first surface transverse of at least two azaacnt boresfeach of said sock et s slidably ieceiving one of said contact elements for movement from a first position with said fingers spaced from the adjacent bores to afford positioning wires therein, to an engaged position with the fingers across said adjacent bores and said slots aligned therewith to engage wires therein, each pair of adjacent bores in each terminal strip section having one of the interconnecting contact elements; and

means for mounting said block to a structure with said second surface spaced therefrom to afford engagement of the jaws of a pliers like tool on said second surface and one of said contact elements in the disengaged position to afford pressing the contact element to the engaged position.

2. A terminal strip according to claim 1, further including extraction means for affording movement of said contact elements from the engaged to the disen' gaged position via the use of a pointed tool such as a screwdriver.

3. A terminal strip according to claim 2, wherein said block has notches along said first surface, with each notch being tapered in depth toward and communicating with a different one of said sockets, and each of said contact elements has an opening adapted to receive the tip of said pointed tool and being positioned at the bottom of said notch when said contact element is in the engaged position, said notch affording insertion of a pointed tool along said first surface and into said opening to provide said extraction means.

4. A terminal strip according to claim 2, wherein said block has notches along said first surface, with each notch being tapered in depth toward and communicating with a different one of said sockets, and each of said contact elements has a tab projecting normally from its end opposite the fingers, said tab being positioned to.

project over one of said notches when said contact element is.in the engaged position, said notches and tabs affording the insertion of a pointed tool therebetween to provide said extraction means.

5. A terminal strip according to claim 1, wherein at least one of said contact elements includes a protrusion generally at a right angle from its end opposite said fingers, said protrusion having a generally centrally located tapped hole, and a screw threadably engaged in said tapped hole and projecting generally normally from said first surface.

6. A terminal strip according to claim 1, wherein at least one of said contact elements includes a rectangular tab at its end opposite said fingers, said tab having sufficient length to project above said first surface when the contact element is in the engaged position and being the male tab of a quick connect terminal.

Claims

1. A terminal for electrically interconnecting sets of wires, comprising: a plurality of resilient conductive contact elements each having spaced fingers defining at least two wire accepting slots therebetween adapted for forceful entry of a wire segment under a force sufficient to resiliently separate said fingers to form a positive electrical connection with the wire; a block of insulating material defining a plurality of terminal sections each having opposite first and second surfaces, a plurality of spaced bores in the block between said surfaces each adapted to receive a said wire, and a plurality of sockets extending from said first surface transverse of at least two adjacent cavities, each of said sockets slidably receiving one of said contact elements for movement from a first position with said fingers spaced from the adjacent bores to afford positioning wires therein, to an engaged position with the fingers across said adjacent bores and said slots aligned therewith to engage wires therein, each pair of adjacent bores in each terminal strip section having one of the interconnecting contact elements; and means for mounting said block to a structure with said second surface spaced therefrom to afford engagement of the jaws of a pliers like tool on said second surface and one of said contact elements in the disengaged position to afford pressing the contact element to the engaged position.

2. A terminal strip according to claim 1, further including extraction means for affording movement of said contact elements from the engaged to the disengaged position via the use of a pointed tool such as a screwdriver.

4. A terminal strip according to claim 2, wherein said block has notches along said first surface, with each notch being tapered in depth toward and communicating with a different one of said sockets, and each of said contact elements has a tab projecting normally from its end opposite the fingers, said tab being positioned to project over one of said notches when said contact element is in the engaged position, said notches and tabs affording the insertion of a pointed tool therebetween to provide said extraction means.