US2848633A - Electrical contact brush biasing arrangement - Google Patents

Description

ELECTRICAL CONTACT BRUSH BIASING ARRANGEMENT N m M A T A Z Filed Dec. 51, 1956 INVENTOR, Zoven Aromion,

I I l I 48,633 Patented Aug. 19, 1958 ELECTRICAL CONTACT BRUSH BIASING ARRANGEMENT Zaven Atamian, SliermanOaks, Calif., assignor to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware 1 Application December 31, 1956, Serial No. 632,625

1 Claim. (Cl. 310-245) This invention finds general utility in the field of electrical contact brushes and relates particularly to the type of electrical brushes normally employed in commutators and like structures.

In electrical apparatus employing contact brushes, it is common to employ a spring means for biasing a graphite or like type of brush into contact with a moving member such as a commutator. The usual practice in this regard has been to employ either a leaf or a coil type of spring acting directly upon the brush element. With these prior known structures, constant spring rate was not always available, thus applying varying forces to the brush at various positions of the spring. Changes in biasing forces on the brush necessarily alters the contact efliciency as between the brush and the moving member, this situation being undesirable in many types of contemporary electrical mechanism.

In another instance, prior electrical contact brush arrangements employing coil or leaf springs, due to the presence of even minute quantities of foreign material and/or due to wear on both spring components and supporting structure therefor, it has been a common occurrence that various portions of the spring mechanism and/ or the supporting structure for the electrical contact brush would fail to function, seize or bind, thus preventing adequate contact between the brush and the moving member. In many forms of electrical equipment, a high degree of reliability must be maintained and such failure of the contact arrangement cannot be tolerated.

Accordingly, it is one important object of this invention to provide a novel electrical contact brush supporting and biasing arrangement.

Another object of the invention is to provide a novel contact brush biasing means wherein relatively constant low rate force is applied to the contact.

A further object of the invention is to provide an electrical contact brush arrangement having reliable means for biasing the brush into contact with a moving member and wherein seizing, sticking or binding of the elements is reduced to a minimum.

Still another object of the invention is to provide a novel electrical contact brush arrangement having adjustable spring biasing means operatively associated therewith.

Other and further important objects of the invention will become apparent from the disclosures in the following detailed specification, appended claim and accompanying drawing, wherein:

Figure 1 is a plan view of the present electrical contact brush arrangement; and

Fig. 2 is a transverse sectional view taken substantially as indicated by line 22, Fig. 1.

With reference to the drawing, the device hereof includes generally a supporting body 10, a contact brush 11 and biasing means 12. The supporting body may be of any desired configuration and includes means for supporting both the brush 11 and the biasing means 12. In the present instance, the body 16 includes a generally T-shaped groove 13, legs 14 extending substantially laterally in the body 10.

As shown primarily in Fig. 2, a generally square boss 15 is disposed from the body 10 and projects into the groove 13. An insulating member 16 is carried within the boss 15 and has an elongated opening 17 therein. The brush 11, which may be made from any suitable material such as graphite or the like, is shown as being square in cross section and adapted for longitudinal slidable disposition in the opening 17 in the insulation I member 16. Obviously, the particular shape of the brush 11 is a matter of choice, depending upon particular requirements in various mechanisms.

The end of the brush 11, remote from the insulation member 16, may be plated as at 18 with any suitable precious metal such as silver or the like. Thereafter, a laterally extending rod or wire structure 20 is secured to the brush 11 and has end portions 21 that are bent upwardly for a purpose to be hereinafter more fully described.

As shown primarily in Fig. 1, a pair of arbors 22 and 23 intersect the lateral portions 14 of the groove 13 and extend through aligned openings 25 and into recesses 26 in the body 10. The arbors 22 and 23 have slotted heads and are adapted to be locked in position by means of set screws 27 which threadably engage the body 10. The arbors 22 and 23 are adapted to support inner ends of spiral springs 28 and 30 as by means of pins 31 which extend through openings 32 in the ends of the inner springs. Outer ends of the springs 28 and 30 are adapted for attachment with the wire member 20 carried by the free end of the brush 11. The force of the springs 28 and 30, acting upon the brush 11, may be individually adjusted and varied by rotation of the arbors 22 and 23.

It may thus be seen that a dual spring biasing force is simultaneously applied to the brush 11 to urge this brush into constant contact and normal alignment with a moving surface S. The spring rate of the spiral springs is very low, thus maintaining a constant force in spite of wear of the contacting end 33 of the brush 11. As shovm in Fig. 1, it may be seen that a contact wire W may be secured as by soldering to the silver plated end 18 of the contact member 11. The wire W may extend to any suitable point for connection with other apparatus.

It may further be seen that no tendency for the springs to bind will be experienced due to the fact that a pair of such springs, symmetrically disposed, are employed to bias the contact member toward the moving surface. Any even remote tendency of one spring to cause binding will be overcome by the force of the other spring with the possibility of both springs failing at the same time being extremely remote.

Having thus described the invention and the present embodiment thereof, it is desired to emphasize the fact that many modifications may be resorted to in a manner limited by a just interpretation of the following clan'n.

- I claim:

An electrical contact brush mounting arrangement comprising, in combination: an elongated brush, rectangular in cross section, disposed for sliding contact of one axial end with a moving surface; a body for receiving and longitudinally slidably retaining said brush normal to said moving surface; a pair of identical force spiral tension springs disposed on lateral sides of said brush, axes of said springs being parallel to said lateral sides of said brush and normal to a longitudinal axis of said brush; a pair of individual arbors attached to said springs and disposed in openings in said body for connecting ends of said springs to said body; a plated References Cited in the file of this patent UNITED STATES PATENTS Smith Dec. 26, 1871 Van Depoele Feb. 25, 1890 Berger Jan. 11, 1938 Welch Nov. 30, 1954 FOREIGN PATENTS Germany Apr. 11, 1938

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