US3533054A - Electrical terminal structure - Google Patents

Description

Oct.6,19 70 ags E-rAL 3,533,054

ELECTRICAL TERMINAL s'rnuc'runn Filed 001:. a, 1968 42. r 40 26 FIG 8 1 "INVENTORS ALBERT SPRIGGS BY THOMAS 5 MANCINI ATTORNEY United States Patent 3,533,054 ELECTRICAL TERMINAL STRUCTURE Albert Spriggs and Thomas Mancini, Hamilton, Ontario,

Canada, assignors to United-Carr Incorporated, Boston, Mass., a corporation of Delaware Filed Oct. 8, 1968, Ser. No. 765,767 Claims priority, application Canada, Jan. 11, 1968, 59

Int. Cl. H01r 9/08, 11/08 US. Cl. 339-221 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an electrical terminal structure of the serrated bayonet type of improved capability of fabrication assembly and resistance to breakage.

Serrated bayonet type electrical terminal devices are well known. They are usually characterized by a tubular or fiat copper, bronze or brass terminal member having thereon barb means such as serrated teeth projecting therefrom to engage surfaces of an accommodating recess or socket in an electrical insulating carrier member. Heretofore the carrier member has been formed from plastic materials of essential insulating properties and mechanical strength. Phenol resins have been a popular and natural choice for such applications. The moulding properties of phenol resins are particularly satisfactory and being especially inexpensive are widely used for electrical terminal mountings especially in connectors, switch gear, relay components, coil supports and the like.

'It has been observed according to this invention that phenolic plastic materials such as may be well known by the trademark Bakelite, exhibit a low internal viscosity and relatively high rigidity or low order of elasticity to the extent that the same are ordinarily regarded as somewhat brittle. Brittleness is controlled by the inclusion of substantial filler material which reduces cost and increases resistance to mechanical shock. Nevertheless the characteristics of such material under continuous stress will lead to cracking, warping and failure of insulating properties. Thus the proper electrical use of a low internal viscosity, low order of elasticity of material such as derived for electrical applications from phenolic glass resins should avoid stress or deformation of any kind in connecting a terminal to an insulate body of such material. In spite of the fact that such information is known to many skilled persons serrated bayonet type terminal devices have been inserted into sockets within phenolic class supports for probably more than fifty years. The immediate failure of the brittle support has been avoided by substantial use of filler material. However, the basic characteristics of such a support material do not provide any resistance to grip the terminal other than that available from the filler material used. Thus such terminal assemblies have a propensity for shaking loose in use. Of the bayonet type of terminals the split hollow tube providing outward elastic pressure against the walls of the receiving socket is the more satisfactory in its endurance under vibration or disturbing force.

It is, the main object of this invention to provide a bayonet type electrical terminal device of fiat strip form adapted to endure heavy vibration or disturbing forces 3,533,054 Patented Oct. 6, 1970 p ice by support under elastic tension in an elastomer insulating material of high internal viscosity such as may be derived for example, from vinyl classes of resins, such as polyvinyl chloride and other forms having a strain memory or ability to recover a moulded form when distorted therefrom such as materials known by the trade names nylon, Dacron and Orlon.

It is a further object of the invention to provide an electrical terminal structure especially for coil end supports which is adapted to be moulded in a two part mould without necessitating socket withdrawal inserts thus to take advantage of elastic properties of the elastomer material used.

Other objects of the invention will be apparent from a study of the following specification taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a coil wound upon a core form or spool having coil form ends carrying the terminal structure of the invention;

FIG. 2 is an enlarged exploded view of right hand fragment of FIG. 1;

FIG. 3 is an elevation of the assembled components of FIG. 2;

FIG. 4 is a section of the line 4-4 of FIG. 3;

FIG. 5 is a perspective elevation of prior art structure;

FIG. 6 is a view similar to FIG. 5 but of structure of the invention sectioned as at line 6-6 of FIG. 4;

FIG. 7 illustrates a two-piece die technique for moulding the terminal support of the invention; and

FIG. 8 is section on the line 8 8 of FIG. 2.

In FIG. 1 an ordinary but not exclusive use of the invention is shown. Coil winding 10 wound upon core 11 extends between core ends (sometimes referred to in the art as spool ends, core end plates, end supports or flanges) 12 and 13. It is convenient to form such spool ends of an insulating material not only to assist in protecting coil 10 but also to provide a suitable insulate support for making electrical connection of coil wires 14 and 15 to suitable terminals 16 which may be mounted on the one or both spool ends. In many other electrical applications a coil associated with spool ends requires terminal connections which are proof against shock vibration and aging.

As described above and referring in more detail to FIG. 5, a fiat strip serrated bayonet type connector 17 of the prior art presents rearwardly flaring spur elements 18 adapted by their sharp pointed spur tips 19 to physically scrape rigid surfaces 20 of a hexahedral socket 21 which usually is in the form of a closed. socket having one entrance opening only but which in the present instance is shown in a mouldable form with an open face 22. Such prior art connection is not generally used except in short life connections where no vibration or shock is expected. The form is exceptionally inexpensive to manufacture especially where socket 21 is open-faced as shown permitting a two piece forming die within retractable inserts.

The present invention is addressed to the problem of such prior art class of connector and realises its modification and application to long life connections adapted to endure heavy vibrations and shock. Thus in FIGS. 2 to 4 and 6 and 8 the connector of the invention embodies a serrated bayonet type rigid metal strip 23 having rearwardly flaring spur elements 24 with slightly radiused spur tips or retaining shoulders 25 to press into the material of the terminal support 26 in the region of the dovetail surfaces 27 of open sided dovetail socket 28. Outer free portions 29 of outwardly converging dovetail surfaces 27 substantially overlie the outer or exposed surfaces 30 of the connector. Thus the connector 23 cannot be moved laterally out of the retaining dovetail socket. The connector support 26 is made according to this invention from an insulate elastomer of high internal viscosity and relatively high rigidity characterized by strain memory such as a polyvinyl chloride and similar thermosetting materials having a strain memory.

A two piece moulding techniques may be employed as shown in FIG. 7 by providing cavities 31, 32 and 33, 34 in mould plates 35, 36 embodying male dovetail portions 37 adapted upon separation of mould plates 35, 36 by arrows 38, 39 to separate from the moulded part by flexing of the latter thereabout due to sliding of surfaces 30 thereover. The part section formed is shown in FIG. 8 and demonstrates a slot opening 40 formed at a transverse angle of 45 degrees about a right angular mould parting line 41. In addition a spur retaining boss 42 is simultaneously formed with a ramp surface 43 adapted to accommodate the insertion of a terminal strip thereover to a socket seated position as shown in FIGS. 3 and 4 at which boss 42 projects into backing aperture 44 of the electrode 23 As indicated in FIG. 6, the material of the support gradually flows toward and about the retaining shoulder 25 rendering the terminal mounting eifectively permanent after a period of days, weeks or months depending upon the rigidity of the material. This action however is not essential during the early life of the connector mounting but is required only to the extent that the socket effectively increases its support over a period of time by virtue of the memory characteristic of the material as contrasted with the prior art form of support socket opening up due to shrinkage and cracking.

The invention provides a successful connector and support for a large variety of applications in which strip bayonet connectors could not be used heretofore.

We claim:

1. In an electrical terminal structure of the flat-bayonet type: a terminal bayonet strip having rearwardly flared spurs thereon each terminating in an outward gripping shoulder of small radius; an insulate elastomer supporting body of high internal viscosity having physical properties under strain adapted for cold flow to recover an unstrained shape; and an open-faced terminal socket in said body having surfaces in strain engagement accommodating said shoulders at least of said strip inserted therein, and said socket is of dovetail form in section presenting outwardly converging surfaces overlying a substantial portion of said terminal inserted therein.

2. The structure of claim 1 and a ramped backing boss in said socket and corresponding backing means in said strip engageable thereby to retain said strip in said socket.

References Cited UNITED STATES PATENTS 1,997,198 4/1935 Ogg. 2,015,421 9/1935 Eckstein et al 173-361 2,318,485 5/1943 Herman 33959 2,734,177 2/1956 Gilbert 339-97 MARVIN A. CHAMPION, Primary Examiner R. A. HAFER, Assistant Examiner

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