US1935818A

US1935818A - Electrical terminal

Info

Publication number: US1935818A
Application number: US611801A
Authority: US
Inventors: Henry G Richter
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-05-17
Filing date: 1932-05-17
Publication date: 1933-11-21
Anticipated expiration: 1950-11-21

Description

NOV. 21, 1933. 1 RlCHTER 1,935,818 I ELECTRICAL TERMINAL Filed May 17, 1932 lNVENTOR Patented Nov. 21, 1933 UNITED STATES PATENT OFF ICE Application May 17, 1932.

3 Claims.

My invention relates generally to terminals for circuit elements and, as herein embodied, is specially designed for use with high resistance units. In order to meet trade requirements, the efforts 5 of manufacturers of high resistance units, particularly of the wire-wound type, have been directed towards increasing the resistance value of the unit to the highest possible point while, at the same time, decreasing its overall dimensions.

This has led to the use of extremely fine, closely wound resistance wire, which has so little body,

it will not withstand the heat of a soldering iron and, in consequence, connection between ends of the resistance wire and the terminals of the unit usually have to be made by some form of clamp.

In a well known resistance unit or resistor, which has been extensively used in the art, the clamp employed is formed of a single length of a binding wire, a number of turns of which are first wound on the body or insulation covering of the unit, as an anchorage winding, then an additional number of turns are wound on the exposed end of the coiled resistance wire, as a contact winding and beyond that, a short length of the binding wire is extended outward to serve as the terminal proper.

This wire clamp terminal, while generally satisfactory, has a serious mechanical structural defect, which the present invention is designed to remedy. It has been found that when the wire clamp terminal is subjected to longitudinal strain or a pull, as frequently happens, the contact winding will loosen and unwind, badly or destroying the contact and rendering the unit unfit for further use.

In order to prevent such strain on the wire clamp tending to cause it to loosen and lmwind, as above described, I form the winding and the terminal proper of separate lengths of wire and so relatively arrange them that any longitudinal strain or pull to which the terminal proper may be subjected, will have no eflect in creating an unwinding tendency of either the contact or the anchorage winding and such windings will be maintained tight and secure, thereby incurring good contact with the resistance wire.

A construction suitable for carrying my invention into efiect is illustrated in the accompanying drawing, in which- Fig. 1 is a view in elevation showing my improved terminal applied to a resistor;

Fig. 2 is a longitudinal section through one of the terminals of the resistor, before it is completed by being solder-dipped;

Serial No. 611,801

Fig. 3 shows the efiect of solder-dipping the terminal to complete it, and

Fig. 4 illustrates a modification.

Referring now to the drawing, 1 represents a well known form of resistance unit in which a very fine resistance wire 2, is spirally and closely wound on a core of asbestos or any other suitable material 3, and enclosed, excepting the

ends

4, 4, in a covering of insulation 5.

At each end of the resistance unit a terminal is formed by arranging a short, straight length of comparatively heavy gauge wire 6, in overlapping relation with the end of the unit and securely clamping it in position by a winding of binding wire 7. The overlap of the terminal wire 6, extends beyond the exposed end 4 of' the resistance unit and on to the insulation covering 5, so that the first six or eight turns of the binding wire serve as an anchorage winding, in clamping the terminal wire to the body of the unit, while the remaining turns, over the exposed end of the unit, form a contact in clamping the terminal wire in close relation with the resistance wire.

Thus constructed and arranged, strain or pull onthe terminal wire will have no tendency to unwind either the anchorage or the contact winding, so that unless the terminal wire is pulled completely out of the grip of both windings, which is practically an impossibility, good con- 85 tact between the terminal and the resistance unit will be assured.

To further strengthen the terminal and give it a more finished appearance, I solder-dip it to a depth, including the binding wire and so securely unite the turns against loosening or In showing my improved terminal applied to the particular resistance unit above described, I do not wish to be understood as intending to limit myself to the same, as it will be apparent that the terminal may be applied with equal advantage to other and different units without material, if any modification.

As will be apparent, the gauge of the wire and the number of turns in both the contact winding and the anchorage winding, may be varied to meet the requirements of the,particular form or type of unit to which the terminal is applied, the showing in the drawing being illustrative only and not intended as an accurate guide for practical construction.

Among the most important advantages of the invention may be mentioned the exceptional strengthof theterminal inwithstandingexcessive longitudinal strain, without disturbing, weakening or otherwise impairing contact with the very fine resistance wire and the arrangement for imparting to the terminal this effective contact protection, that is to say, the location of the contact winding between a strong anchorage winding on the body of the unit and the terminal proper, to which the strain is applied.

As a further means of strengthening the terminal, I may modify the construction, as shown, in Fig. 4, in which a stranded wire 6 is employed instead 'of a single wire and the overlapoing ends spread apart under the clamping action of the anchorage winding.

Having thus described my invention, what I claim is:

l. A resistor consisting of a resistance wire spirally wound on a suitable core and enclosed, excepting the ends, in a covering of insulation, a terminal reinforcement in the form of a straight length of wire having one end exteriorly arranged in overlapping contact relation, with the exposed end of the coiled resistance wire, and a winding of binding wire securing the overlapping members together in close contact and forming an enclosing sheath for the same and the adjoining portion of the insulation covering.

2. A resistor consisting of a resistance wire spirally wound on a suitable core and enclosed, excepting the ends, in a covering of insulation, a terminal reinforcement in the form of a straight length of wire having one end exteriorly arranged in overlapping contact relation with both the exposed end of the coiled resistance wire .and a portion of the insulation covering, and a winding of binding wire securing the overlapping members together in close contact and forming an enclosing sheath for the same.

3. A resistor consisting of a resistance wire spirally wound on a suitable core and enclosed, excepting the ends, in a covering of insulation, 2. terminal reinforcement in the form of a straight length of wire having one end exteriorly arranged in overlapping contact relation with both the exposed end of the coiled resistance wire and a portion of the insulation covering, and a winding of binding wire securing the overlapping members together in close contact and forming an enclosing sheath for the same, the said sheath being solder-dipped to unite the turns of the winding.

HENRY G. RICHTER.

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