US 3325775 A
Description (OCR text may contain errors)
June 13, 1967 A. M. ZAK 3,325,775
ELECTRICAL TERMINAL Filed NOV. 8, 1965 I VENTOR. ALFRED M ZAK ATTOQNEYS United States Patent 3,325,775 ELECTRTQQJL TERll IINAL Alfred M. Zak, 611d Casrnere, Detroit, Mich. 4-8212 Filed Nov. 8, 1965, Ser. No. 566,67 3 Claims. (Cl. 339256) This invention relates to electrical connectors, and more particularly to electrical terminal blocks and terminal contacts used therewith.
In many industrial fields, for example, automotive, aircraft and appliance, the use of a great number of disconnectible electrical conductors has become very prevalent. Usually the disconnect feature takes the form of a pair of terminal blocks in which many male and female terminal contacts are arranged such that they can be telescopically engaged and disengaged. Because of space limitations in many instances, the sizes of such terminals have by necessity become progressively smaller, and the problems encountered have become correspondingly greater. As the size (the diameter) of the terminal is reduced, the sheet metal from which the terminal is fabricated is likewise reduced in thickness and with extremely thin sheet metal portions of the terminal become quite flimsy.
Even with such small diameter terminals there remains the necessity of providing a terminal construction which insures good contact between the telescoping terminal members and which at the same time enables the terminals to be solidly anchored within a terminal block, so they will not collapse or distort upon connecting or separating the terminal blocks.
it is accordingly an object of this invention to provide a terminal construction which is admirably suited for fabrication in small sizes and which at the same time is designed so that it can be solidly anchored within a terminal block.
A further object of the invention resides in the provision of a terminal which is designed such that it can be economically produced in progressive dies and after forming, a plurality of such terminals, connected to a carrier strip, can be easily handled and fed to and from a reel.
In the drawings:
FIG. 1 is a fragmentary sectional view of a pair of terminal blocks provided with male and female terminals of the present invention, the terminals being shown partly broken away.
FIG. 2 is a perspective view of the male terminal.
FIG. 3 is a sectional view taken along the line 33 of FIG. 2.
FIG. 4 is a perspective view of the female terminal.
FIG. 5 is a fragmentary sectional view showing the manner in which the terminal of the present invention can be released from within its terminal block.
FIG. 6 is a fragmentary end view of one terminal lock as viewed along the line 6-6 of FIG. 5 with the terminal removed.
In FIG. 1 a pair of terminal blocks 16 and 12 are illustrated. As is conventional, these terminal blocks are formed of an electrical insulating material such as Bakelite. Within block 10 there is arranged a female terminal contact 14, and within block 12 there is arranged a male terminal contact member 16. These two contacts are shown in perspective in FIGS. 4 and 2, respectively. As illustrated, both terminals are of generally cylindrical shape and are adapted to be formed from flat sheet metal in progressive dies. At their outer ends each terminal is formed with a pair of tabs 18 which are adapted to be crimped around the insulating coating 20 of a stranded wire conductor 22. Each terminal is also formed with a second pair of tabs 24 spaced axially from tabs 18, tabs 24 being adapted to be crimped over the bared end of the stranded conductor 22 to provide good electrical contact between the terminal and the conductor.
Terminal 14 is formed with a cylindrical body portion 26 and terminal 16 is formed with a cylindrical body portion 28. The inner diameter of the body portion 26 of terminal 14 is dimensioned relative to the outer diameter of the body portion 28 of terminal 16 such that they have a slight interference fit. For example, in a terminal construction wherein the outer diameter of body portion 28 is about .093 inch, the nominal inner diameter of body portion 26 may be about .003 inch less, so that the insertion of body portion 28 into body portion 26 requires a slight circumferential expansion of body portion 26. The sheet metal from which such terminals are formed has at least a slight degree of resilience, so that the interference fit will provide good electrical contact between the two terminals. The axially extending parting line between the contacting or near contacting longitudinal edges of terminal 14 is indicated at 30-and the corresponding parting line on terminal 16 is indicated at 32.
Terminal block 10 is fashioned with a bore 34 dimensioned to receive the cylindrical body portion 26 of terminal 14 and a counterbore 36 dimensioned to receive the enlarged outer end of terminal 14 at the tabs 18. These two bores are separated by a shoulder 38. The body portion 26 of terminal 14 is fashioned with a pair of radially outwardly extending lugs 44 that are adapted to abut against shoulder 38 and thus limit movement of terminal 38 in a direction inwardly of block 10, that is, in a direction toward the right in FIG. 1.
Terminal block 12 is fashioned with a cylindrical socket 42 adapted to receive the cylindrical body portion 28 of terminal 16 with a rather close fit and a counterbore 44 adapted to receive the enlarged outer end of terminal 16 at tabs 18. The junction between these two bores defines a shoulder 46 which is adapted to be engaged by lugs 48 on terminal 16 to limit the extent to which terminal 16 can move in a direction inwardly of terminal block 12, that is, in a direction to the left as viewed in FIG. 1.
Bore 34 is formed at One side thereof with an axially extending recess or slot 50, and bore 46 is likewise formed with a longitudinally extending recess or slot 52. These slots extend to the inner end faces of the terminal blocks, as indicated at 54, which faces are adapted to be brought into abutting relation when the terminals are telescopically engaged. Slot 50 accommodates a tab 56, and slot 52 accommodates a tab 58. The construction and function of each of these tabs is the same, and for this'reason only tab 56 will be described in detail. Tab 56 is struck inwardly from the wall of body portion 26 about bend line 57, and extends across the hollow interior of body portion 26 at an acute angle to the longitudinal axis of the terminal. At its free end tab 56 extends through an opening 60 in body portion 26 which is diametrically opposite the opening 62 which results from striking tab 56 inwardly. It will be noted that tab 56 engages the edge 64 of opening 60 so that the extent to which it can be flexed outwardly of opening 60 is effectively limited by the edge 64. Edge 64 is located so as to accurately control the extent to which the free end portion 66 of tab 56 projects radially outwardly beyond the outer periphery of cylindrical body portion 26. As is clearly evident from FIG. 1, When terminal 14 is inserted in block with lugs 40 engaging shoulder 38, the end portion 66 of tab 56 is spaced slightly from the end 67 of slot 50.
Tab 58 on terminal 16 is likewise struck inwardly from the cylindrical body portion 28 about bend line 69 and extends across the hollow interior of body portion 28 at an acute angle to the longitudinal axis of the terminal With its free end portion 68 projecting outwardly through an opening 70 in body portion 28. Tab 58 bears against the edge 72 of opening 70 to limit the extent to which tab 58 can flex in a direction outwardly of body portion 28. With terminal 16 fully inserted in block 12, that is, with lug 48 engaging shoulder 46, the free end portion 68 of tab 58 is spaced slightly from the end 69 of slot 52. In actual manufacture, tabs 56, 58 are overbent slightly so that they are preloaded, that is, they are in pressure contact with the backing edges of the respective holes 60, 70 through which they project. This eliminates entirely any problem of maintaining close tolerances in the bending of these tabs.
The leading end of terminal 16 is preferably formed with a tapered nose 74 to facilitate its insertion in the open end 76 of terminal 14. In addition, tapered nose 74 is fashioned with a radially extending lug 78 which is aligned with the parting line 32 on the cylindrical body portion 28. Lug 78 is preferably bent up from one edge of the body portion and the adjacent edge is notched slightly as at 80, so that the lug will be disposed on the center line of the terminal. The leading edges of terminal 14 are notched or tapered as at 82, to facilitate entry of lug 78 between the contacting edges which form the parting line 30 on terminal 14. Terminal 14 is also formed with an aperture 84 positioned to receive lug 78 when terminal 16 is fully inserted in terminal 14. To facilitate withdrawal of terminal 16 from terminal 14, the leading edges of aperture 84 are tapered as at 86.
Each terminal is engaged within its respective terminal block by inserting the terminal through the block from the outer end thereof. In the case of terminal 16 and block 12, for example, terminal 16 is inserted leading end foremost through the open end 87 of bore 44. The portion of the block aligned centrally of tab slot 52 and adjacent shoulder 46 is fashioned with a radial slot 88 to accommodate lug 78. As the end of tab 58 engages shoulder 46 it is deflected inwardly in the manner of a leaf spring through opening 70 so that the tab can pass into the smaller bore portion 42. When tab 58 is aligned with slot 52, the tab snaps radially outwardly into slot 52 to the extent permitted by the edge 72 of the opening 70 in the terminal. The terminal is thus effectively locked in the terminal block. Terminal 14 is engaged within its terminal block 10 in substantially the same manner. It will be understood that normally each terminal block retains a plurality of laterally spaced terminals.
When it is desired to interconnect the terminals, terminal block 12 is manipulated relative to the terminal block 10 to align each of the nose portions 74 of terminals 16 with the open end 76 of a corresponding terminal 14 in block 10. Insertion of the body portions 28 into the terminal block 10 is facilitated by a slight chamfer 90 at the open end of the bore 34 of terminal block 10. As the leading ends of terminals 16 are advanced into terminals 14, the lug 78 on each terminal 16 enters between the tapered edges 82 on the corresponding body portion 26 to facilitate the circumferential expansion of each terminal 14 and thus separate the contacting edges forming the parting line 30.
When the juxtaposed faces 54 of the two terminal blocks come into abutting relation, each lug 78 snaps into a corresponding aperture 84 and thus causes each body portion 26 to contract into tight engagement with the associated body portion 28 of terminals 16. To disconnect the terminals the operation is reversed, and the force required to pull them apart is lessened by the provision of lug 78 in conjunction with the tapered edges 86 of aperture 84.
It will be appreciated that where each terminal block contains many terminals, a rather substantial force may be required to telescopically engage the terminals. However, in view of the fact that the tabs 56, 58 are rigidly backed adjacent their outer ends against edges 64, 72, respectively, there is no tendency for these tabs to collapse, even though they are of rather substantial length. Their rigidity can be increased if desired by forming them with a slight crown in cross section, as illustrated. The fact that the tabs 56, 58 are of substantial length is, however, a definitely advantageous feature of my terminal construction. Being of substantial length, they deflect rather easily and have near perfect recovery as compared to a relatively short tab which would have to bend to a substantially greater extent in order to insert the terminal in the terminal block. Even though the tabs themselves are of substantial length, nevertheless they project radially outwardly from the terminal only a slight extent. For example, on a .093 inch terminal the tab is designed to project radially beyond the cylindrical body portion only .020 inch. This contributes to their rigidity.
Likewise, by forming the tabs 56, 58 so that they extend across the hollow interior of their respective terminal, each of the terminals can be readily removed from the terminal blocks by inserting a removal tool, such as indicated at 92, through the open end of the terminal to deflect the tab inwardly to a position where it will clear the end of the slot in which it is disposed. As pointed out previously, each tab has sufiicient clearance with the inner end 67, 69 of the corresponding slot in the terminal block to enable the tab to flex radially inwardly through the opening 70 or 60, as the case may be. In the drawing the inclination of tabs 56, 58 to the axis of the terminals is illustrated as about 45. This inclination can be increased or decreased within limits but it is imortant that in any event the tab be inclined to the axis of the terminal at an angle substantially less than 90 in order to obtain the above-described advantages of my invention.
Another important feature of the present invention lies in the fact that even though the terminal may be formed of a lightweight sheet metal, for example, sheet metal having a thickness of .0126 inch in the case of a terminal having a diameter of .093 inch, the terminal itself is relatively rigid and does not have any long, flimsy radial projections on its outer surface. This is important because terminals of this type when formed on progressive dies are advantageously interconencted by lugs 94 with carrier strips 96 to enable handling of the terminals as reels. For example, until the individual terminals are crimped onto a wire, they are connected to the carrier strips or runners 96 so that they can be reeled. The die which crimps the tabs 18 and 24 is preferably fashioned so that it simultaneously shears the lugs 94 from the opposite ends of the treminals. Since these terminals are handled as reels for purposes of convenience, it is important that the terminals have no flimsy exterior projections which would readily entangle with similar projections or the like on the terminals on the next successive convolution of the reel.
1. An electrical connecting means comprising a pair of male and female terminal members dimensioned for snug telescopic engagement, said female member having a hollow portion provided with a pair of juxtaposed separable edges which extend axially of the terminal member, said male member having a radially extending projection adjacent one end thereof adapted to engage between said juxtaposed edges to separate them and there by circumferentially expand the hollow portion of the female member when telescopically engaged therewith, said female member having an opening in the Wall thereof contiguous to and in alignment with said juxtaposed edges -to receive said projection when the members are fully telescoped to allow said edges to return toward their free condition and thereby circumferentially close on the male member.
2. The combination set forth in claim 1, wherein said edges are spaced apart slightly at the leading end of the female member to provide a tapered lead-in slot for the projection.
3. The combination set forth in claim 2, wherein the end of said aperture toward the leading end of the female member is generally V-shaped to facilitate Withdrawal of the male member from the female member.
References Cited UNITED STATES PATENTS 1,425,153 8/1922 Vigneault. 2,944,241 7/ 1960 Londell 3 39-91 2,974,302 3/1961' Ellis 339278 10 MARVIN A. CHAMPION, Primary Examiner.
EDWARD C. ALLEN, Examiner. P. A. CLIFFORD Assistant Examiner,