US2368548A - Electrical terminal - Google Patents

Description

A. G. KALSTEIN ELECTRICAL TERMINAL Filed Sept. 19, 1941 I \NVENTOR Abrakam fl 'ads'iein ATTORNEYS Jan. 30, 1945.

Patented Jan. 30, 1945 ELECTRICAL TERMINAL Abraham G. 'Kalstein, New Bedford, Mass., 23-

signor to Aerovox Corporation, New Bedford,

Mass, a corporation of New York Application September 19, 1941, Serial No. 411,446

' 4 claims. ('01. 174-153) While the invention has particular application to encased electrical condensers incorporating oil dielectric, it is of broader application to other apparatus that includes oil or other ingredients which might seep therefrom in the absence of a. thoroughly liquid tight terminal.

As conducive to a clear understanding of the invention, it is noted that where such terminals are equipped with rigid washers of Bakelite" or the like, that are faced with rubber to impart some elasticity to the compressed composite washer structure intervening between the terminal and the case, difliculty is apt to arise in that such washers are not strictly uniform in thickness, so that in the usual riveting operation, the terminal will be loose where the washer is slightly under the desired thickness and such washer will crack, split or break, where it is in excess of desired thickness, the resultant unit in either case being unsatisfactory both from the standpoint of electrical insulation and liquid tightness. Moreover, the composite rubberfaced Bakelite disk is not only expensive in construction, but 'also for all'practical purposes precludes a direct bonding of the rubber facing to the metal of the stud, so that in assembly, the stud and washer must be separately handled which further adds to the cost.

It is among the objects of this invention to provide an electrical terminal unit of reduced cost, and uniformly well-insulated and liquidtight, that may be riveted in place with thorough dependability, regardless of variations incurred in the normal course of manufacture and in which the terminal structure together with its oil sealing element may be prefabricated as a single unit.

In the accompanying drawing in which is shown one of various possibleembodiments of the several features of the invention,

Fig. 1 is a plan view partly in section, of a condenser structure incorporating the new terminal,

Fig. 2 is a perspective view of the terminal element as a separate article of manufacture,

Fig. 3 is a view in longitudinal cross-section through the terminal element showing its relation to the can aperture, and

Fig. 4 is a transverse sectional view taken on line 4-4 of Fig. 1.

Referring now to the drawing, there is shown I a generally conventional type of oil impregnated terminals T1 and T2. Each terminal involves desirably a hollow shankhaving a unitary circular flange l2 between the ends thereof. The outer length I3 of the shank at one side of the flange is threaded for application of a conventional terminal nut (not shown) and the shank length N at the opposite side of flange I2 is unthreaded. An insulating fiber plate I5 is desirably disposed against the inner face of the case l0 through which the shank l5 extends and the hollow inner end of the shank is rolled over at l6 against a metal washer H which may, if desired, be backed by a locking spring Washer 18 engaging the fiber back. I

Intervening between the flange l2and the outer face of the case I0 is a soft rubber washer can.

Thus in rolling over the inner end of the shank as at 16 to install the preassembled terminal to the case, the rubber washer l9 willbe subjected to compression between the flange l2 and the case l0. Desirably the washer is sufflciently thick, so that regardless of minor variations therein in the course of normal manufacture, it will be substantially compressed in heading over the inner end of the shank in the usual riveting machine. Of each 1,000 terminals thus applied, 1,000 will therefore be liquid tight and satisfactorily insulated with respect to the easing. The rubber in each case will be under compression and will securely seal the gap intervening between the terminal shank l4 and the casing aperture 20. The danger, on'the one hand, of loose terminals or on the other of cracked washers due to the use of a rubber coated Bakelite" disk that depart from desired thickness is completely obviated, the cost of the terminal is reduced and the ease of assembly is enhanced.

The seal effected atthe terminal is thoroughly moisture proof. Any liquid within the unit that might otherwise tend to'seep past the fiber plate I5 will be confined to the interior of the casing. Even in extremely humid atmospheres the seal at the terminal is effective also to prevent entry of moisture from the exterior to the interior of the unit. The most severe present-day requirements for moisture proofing are met by the terminal of the present invention. The need for the makeshift of painting less satisfactory terminals in an effort to enhance the rigidity and moisture proof properties thereof are obviated.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Electrical equipment comprising a metal case, an insulating backing for said case, a terminal stud through corresponding apertures in said backing and said case and having a unitary flange at the exterior of and spaced from said case wall, a substantially flat soft rubber disk wholly at one side of and directly engaging the race of said flange and bonded thereto to form a.

unitary structure therewith, the inner end of said stud being headed over and by pressure transmitted through said flange maintaining said soft rubber washer under compression against said aaeaue flange, the periphery of said flange being exposed.

2. The combination recited in claim 1 in which the soft rubber disk has a unitary hub extendini into the aperture in said case for accurate centering of the terminal stud with respect to said aperture.

3. As an article of manufacture, a terminal stud for electrical equipment, comprising a shank having a unitary median circular flange said shank being threaded at one end thereof and being hollow at the opposite end thereof and a substantially flat molded soft rubber disk at the face of said flange which is nearest to said hollow shank 'end and in permanent bonding engagement with said flange, the periphery of said flange being exposed.

4. As an article of manufacture, a terminal stud for electrical equipment, com-prising a shank having a unitary median circular flange said shank being threaded at one end thereof and being hollow at the opposite end thereof and a substantially flat molded soft rubber disk molded into flrm unitary engagement about said shank and against the face of said flange which is nearest to said hollow shank end, the periphery of said flange being exposed.

ABRAHAM G. KAISTEIN.

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