US2772404A - Terminal - Google Patents

Description

S. E. PETERS TERMINAL Filed Oct. 24, 1952 I INVENTORI SAMUEL E. PETERS ATTORNEYS:

United States Patent TERMINAL Samuel E. Peters, Racine, Wis., assignor to The Dumore Company, Racine, Wis., a corporation of Wisconsin Application October 24, 1952, Serial No. 316,621

3 Claims. (Cl. 339-456) This invention relates to a terminal for effecting electrical connection with a brush holder or similar device.

The conventional brush holder includes a cylindrical brass sleeve within which the brush is slidably mounted, suitable electrical connection being provided between the sleeve and the brush proper. Electrical connection between the field circuit of the motor and the brush sleeve is made by providing a terminal which surrounds the brass sleeve, and to which the end of the field lead may be soldered or otherwise secured.

The characteristics that must be possessed by such terminal are first, a very secure mechanical connection must be made; and second, that good electrical contact be provided to avoid over-heating.

The mechanical requirements imposed on such a terminal are quite severe due to the fact that motors embodying this type of construction are frequently incorporated in tools and appliances wherein the motor is subjected to severe vibration. Therefore, insofar as a secure mechanical connection is concerned, such a terminal must be able to withstand such vibration without becoming loosened. quently replaced, it is desirable to provide a terminal which can easily be removed or applied to a brush holder, without the necessity of using special tools.

One type of terminal now in use comprises a metal ring which includes a screw threaded device for drawing up the ring so as to provide good electrical and mechanical contact. The screw threaded device is also used to secure a terminal member to the ring in electrically conducting relationship. The disadvantage of this screw and ring type of terminal is first; the matter of expense; second, removal and application require the use of a screw driver; and third, unless applied with care, the screw may be come loosened, due to vibration.

To overcome the foregoing objections, various resilient or spring types of terminals have been proposed which frictionally embrace the brass sleeve, thus eliminating the screw. For this purpose, the brass sleeve is generally provided with a groove to receive such a terminal. The spring terminals heretofore used have been limited functionally by the fact that only a comparatively small contact area is provided, thereby causing heating and excessive voltage drop, and sometimes annealing of the terminal. Furthermore, in order to obtain a mechanical connection which is comparable with that provided by the screw and ring type, it has been necessary to make such resilient type terminals from a copper alloy wire of fairly heavy gauge with the result that some difficulty is encountered in applying the same to the brush holder, especially when the restricted space requirements are taken into consideration.

It is an object of the present invention to provide an improved spring terminal which overcomes the aforementioned difficulties and objections to the terminals of the prior art.

It is a further object of the present invention to provide a spring terminal which has a double wrap of spring,

Furthermore, since brush holders are frethereby giving greater contact area than that provided by the single wrap spring terminals in the prior art, and also providing an improved mechanical gripping action.

A still further object of the present invention is to provide a double wrap spring contact which is so formed as to prevent the two convolutions or turns from telescoping or overriding, since this would materially reduce the electrical contact area.

Still another object is to provide an improved spring contact which can be easily snapped into or out of place on a brush holder without the use of tools. In this connection, I provide the terminal with a symmetrically disposed loop portion which can serve as a handle for convenient manipulation. Due to the symmetrical disposition of the loop, the frictional grip will be maintained irrespective of the circumferential position of the loop with respect to the brush holder, or of any force applied to the loop. In other words, the frictional grip will be neither tightened or loosened due to any shift in the angular position of the terminal with respect to the brush holder. The conductor is secured to the terminal at this loop portion.

Other objects, features and advantages will become apparent as the description proceeds.

With reference now to the drawings in which like reference numerals designate like parts:

Fig. 1 is a view of a brush holder and terminal according to my invention;

Fig. 2 is an end view of Fig. 1;

Fig. 3 is an enlarged view of the clip itself;

Fig. 4 is a view showing the manner in which the conductor is attached to the terminal;

Fig. 5 is an edge view of Fig. 3;

Fig. 6 is a View showing the manner in which the terminal can be positioned onto the brush holder; and

Figs. 7 and 8 are views, partially in section, showing the terminal as applied to modified types of brush holders.

With reference now to Figs. 1 and 2, the reference numeral 10 designates generally a brush holder which comprises a brass sleeve 11, a portion of which is surrounded by an insulating sleeve 12. The brush, not shown, is disposed within the sleeve 11. The terminal which surrounds the brass sleeve 11 in electrical conducting relationship therewith is designated by the reference numeral 13. The exposed portion of the brass sleeve may be provided with a shallowgroove 14 of a width to receive the terminal.

As shown in Fig. 2, a conductor 15 may be secured to the terminal 13 at a tab or loop portion 16.

As shown in Figs. 3 and 4, the terminal itself comprises a length of wire which is formed into a helix of somewhat less than two turns. The wire is formed from resilient stock, such as a Phosphor bronze or beryllium copper wire, No. 16 B & S gauge. The loop 16 is formed in the terminal at the mid-point of the length of wire from which the clip is: formed. Thus, the loop divides the terminal into two arm portions 17 and 18, each of which is somewhat less than 360 in length. The end portion of each arm is bent up, as indicated by the reference numerals 19 and 20.

There is thus provided a terminal which is easily expansible to the slight extent necessary to enable it to be snapped over the end of the brush holder and into the groove 14.

The bent up ends 19 and 20 prevent the separate convolutions or turns from telescoping upon each other or overriding, thus causing full contact to be maintained with the brush holder. Furthermore, the bent up ends provide easier assembly and dis-assembly with the brush holder. If the bent up ends were not. provided, there would be a sharp edge which would tend to bite into the brush holder, and which would catch on the end asym t pp n .Linstance,.theamount of ofiset can beanywhere between zeroz and substantially 60. degrees,: thereby. providing for each.arm.- alength ofsubstantially three hundred degrees or. more.

.;,snapped .in place.

surface of the brush holder as the terminal is being snapped into place.

Thus, the bending of the ends provides two symmetrit. eallys disposedrounded, portions. 21 and 22 which bear against the sleeve. in. such a manner v that. the angular positionof .theaterminalawith respect-to the sleeve can tIt.-,will be. observed that therounded end. portions 21 and-22 areofi'set from thecenter line of the U-shaped loop portion less than 90 degrees so that a full and action .can :take place. For

.Eig. 4-showshthe manner in which the bared end 24 As shown in The application of the terminal to the brush holder is illustrated in Fig. 6; one side of the terminal is first hooked over the edge of the groove; then finger pres- .sure applied to the opposite side of the terminal will cause the same to expand sufiiciently so that it will be sure is applied to the loop 16, and the terminal-will snap off of the brush holder without any difficulty.

Instead of a single double width groove 14, asshown inlliig. 1, the brush holder may be provided with two separate parallel grooves 27 as shown in Fig. 7, or with a spiral groove 28 as shown in Fig. 8. The parallel .groove-is as effective as the spiral groove due to the natural bridging of the groove land by the loop of the :terminal.

Actually, the terminal herein shown provides good electrical contact even though the brush holder is not grooved; I however, agroove is preferable from the viewpoint of a secure. mechanical connection.

Various modifications-andchanges may be made in that embodiment of my invention which has been shown and-described herein without departing from the spirit of the invention. as pointed out in the following claims.

I claim: 1. In combination, a brush holder having a grooved To remove the terminal, lateral pres- H portion adjacent one end, a spring terminal disposed within said groove, and a conductor secured to said terminal, said terminal comprising a resilient wire helix of slightly less than two turns and having a symmetrically disposed loop dividing said helix into two symmetrically disposed arm portions each providing an independent gripping action, each arm portion being of a length substantially less than 360 so that each arm may be expanded solely by fieXure, whereby said spring terminal may be applied to said brush holder by slipping the same over the end of said brush holder in a lateral direction, said conductor being twisted and soldered to said loop, and said loop providing 'a handle for manipulation of said spring terminal insaid lateral direction.

2. A brush holder terminal comprising a spring Wire helix of from one and one-half to two turns, said helix being provided with a symmetrically disposed loop which dividesthe helix-into-two armportionsof from th'reefourths ofa. turn to one .turn each and eachproviding an independent gripping action, the'end portionsof said arms being bent outwardly to prevent the turns from overriding one upon the. other, and the portions adjacent. said bent endportions constituting symmetrically disposed roundedbearing portions.

3. A spring terminal for cooperation with the brush holder sleevevofa motor comprising a length of resilient wire having a U-shaped loop formed at substantially its mid-point, the two arms of said length of wire each .being curved throughout substantially 300soas toprovide a double wrap and each providing an independent gripping action, the end portions ofeach 0f saidarms being bent upwardly to prevent the free end from passing beneath the. adjacent convolution.

References Cited in the file of this patent UNITED STATES PATENTS 1,557,111 Rutledge Oct. 13, 1925 1,606,506 Bushnell Nov. 9, 1926 1,865,207 Persons June 28, 1932 2,454,230 Stickney Nov. 16, 1948 2,602,105 'W'elch July 1, 1952 FOREIGN PATENTS 10,074/02 Great. Britain May 1, 1902 242,391 Great Britain Mar. 12, 1925 434,825 France Dec. 7, 1911 I 835,164 Germany Mar. 27,. 1952 504,922 Canada Aug; 10,1954

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