US2745075A - Insulated terminal - Google Patents

Description

May 8, 1956 R. L. SIMPKINS ET AL 2,745,075

INSULATED TERMINAL Filed Jan. 3l, 1951 INVENTORS.

BY #ou/ARD A. ELL/arr United States Patent O INSULATED TERMINAL Robert L. Simpkins, Royal Oak, John S. Materka, Dearborn, and Howard A. Elliott, Detroit, Mich., assignors t0 Essex Wire Corporation, Detroit, Mich., a corporation of Michigan Application January 31, 1951, Serial No. 208,768

2 Claims. (Cl. 339-26) The present application relates to an insulated terminal and the novel method of forming the same, and more particularly to an insulated terminal particularly adapted for use with spark plug electrodes.

There has been a considerable amount of work done in the eld of spark plug insulators in an attempt to provide eiiicient insulation for the unit comprising the terminal, the portion of the attached cable adjacent the terminal, and the spark plugs. The purpose is to protect the terminal and spark plug from dirt, oil, and moisture.

It is this problem of providing an eiiicient, practical seal which applicant is primarily concerned with, and therefore, it is a principal object of the present invention to provide an insulated terminal which is simple and efficient in construction and which is extremely easy to handle in use.

It is another object of the present invention to provide a method for manufacturing an insulated terminal which is simple, involves a minimum number of steps, and which is suited for rapid production at low cost.

It is a further object of the present invention to provide an insulated terminal construction including a cable, a terminal, and an insulating cap, wherein the insulating cap iits tightly about the terminal and wherein the joint between the terminal and the cable is, eiciently sealed against moisture, oil, dirt and the like.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

in the drawings:

Fig. l is a side elevation of an insulated terminal construction embodying one modification of the present invention, the free end of the cable being broken off for convenience.

Fig. 2 is an enlarged side View similar to Fig. l, but with the near half of the construction being broken away to reveal the interior construction of the device.

Fig. 3 is a section taken along the line 3 3 in the direction of the arrows, Fig. 2 and revealing the internal construction of the electrode-receiving leg of the insulated terminal of the present invention.

Fig. 4 is a side view of another modification showing the use of the present invention with a straight terminal rather than an elbow terminal, a portion of the construction being broken away for clarity.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

A preferred embodiment of the invention is disclosed in Figs. 1 3 of the drawings wherein a cable 10 comprises the wire 12 and the surrounding insulating material 14. An elbow terminal is indicated at 16 and is generally of the type disclosed in U. S. Patent No. 2,553,083, and includes the conductor-receiving leg 18 and the electrodereceiving leg 20. Proper electrical contact is maintained between the cable 10 and the conductor-receiving leg 18 by the inwardly extending nib 22 which pierces the insulation 14 and contacts the wire 12. The elongated holes 24 in the electrode-receiving leg 20 are provided to give the said electrode-receiving leg more exibility. A shield 26 is litted over the electrode-receiving leg 20 to prevent molding material from entering the interior of the terminal 16 through the holes 24 when the protective cap 28 is molded into place as hereinafter described.

The cap 23 is molded onto the terminal 16 and the adjacent portions of the attached cable 10 by the method disclosed in U. S. Patent 2,578,492, assigned to the assignee of the present invention. The terminal with the cable attached is placed in the mold, and the insulating material 29 which comprises the cap 28 is injected into the mold. Although any suitable protective substance such as rubber or the like, may be used, it has been found that particularly desirable results are obtained when neoprene is used for both the insulating material 14 on the cable 10 and the insulating material 29 which forms the cap 28. After the cap 28 is molded over the terminal 16 and cable 10, the unit is cured, forming a homogeneous bond at the points indicated at X of neoprene to neoprene.

The seal at X is under no tension as in previous constructions, and the seal will last the life of the cable and cap.

In a 15,000 volt corona test with the parts in place over a spark plug, the conventional construction developed severe corona cutting action in l0 to l5 minutes. This cutting is a series of longitudinal cracks occurring wherever the insulating material is stressed even slightly. The construction of the present invention was subjected to the same test for l5 hours without evidence of cutting. This is believed to be primarily due to the fact that the molded cap in the device of the present invention is not under stress, since the curing relieves the internal molding stresses, and there is no stress developed due to deformation of the cap as in most conventional construeA tions. Another factor which contributes to the desirable qualities of the present device is the system of injection molding of the cap wherein the uncured stock is subjected to 5 or 6 times as great a iinal pressure as developed by compression moldings. This results in a higher density in the cap which adds to its strength. The vulcanized seal at X is effective against water, dirt, oil, and chlorides encountered by engines, and keeps the porcelain on the spark plugs clean and dry. This prevents electrical charges from tracking down the porcelain to render starting in wet and humid weather very diiicult.

The modication of the present invention shown in Fig. 4 of the drawings utilizes a straight terminal 16a rather than an elbow terminal. Otherwise the construction is identical to that shown in Figs. 1 3 of the drawings. The corresponding portions are numbered the same as in the rst modification and have the letter 1'1" appended thereto to designate the modification. The insulating material 29a of the cap 28a is bonded to the insulating material 14n of the cable lila to form the seal at X in the same manner as described in connection with the construction disclosed in the rst mcdication of the present invention.

Having thus described our invention, we claim:

l. An insulated sleeve type terminal particularly adapted for use with a spark plug comprising an inner metal shell having a conductor-receiving portion and an electrode-receiving portion, a conductor having insulating material thereon extending into said conductor-receiving portion and in electrical contact with said conductor receiving portion, and a cap of protective dense material combining a neoprene compound molded over said terminal and the adjacent portion of said conductor and bonded to the insulating material on said conductor, said cap extending beyond the free end of the electrode-receiving portion to provide a protective cover.

2. An insulated sleeve type terminal particularly adapted for use with a spark plug, comprising an inner metal shell having a conductor-receiving portion and an electrode-receiving portion, a conductor having insulating material comprised of a neoprene compound thereon extending into said conductor-receiving portion and in electrical contact with said conductor-receiving portion, and a cap of protective dense material comprising a neoprene compound molded over said terminal and the adjacent portion of said conductor and bonded to the insulating material on said conductor, said cap extending beyond the free end of the electrode-receiving portion to provide a protective cover.

References Cited in the le of this patent UNITED STATES PATENTS 1,139,973 Herz May 18, 1915 1,376,844 Weber May 3, 1921 1,763,115 Wermine June 10, 1930 1,970,767 Rabezzana Aug. 21, 1934 1,997,074 Novotny Apr. 9, 1935 2,015,590 Cavanagh Sept. 24, 1935 2,396,872 Miller et al Mar. 19, 1946 2,421,155 Miller et al. May 27, 1947 2,428,608 Bass Oct. 7, 1947 2,436,712 Burrell et al Feb. 24, 1948 2,452,847 Frei Nov. 2, 1948 2,550,358 Le Grand Apr. 24, 1951 2,553,083 Elliot May 15, 1951

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