US2986666A

US2986666A - Brush assembly units

Info

Publication number: US2986666A
Application number: US814120A
Authority: US
Inventors: Tsutsumi Kentaro
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-05-18
Filing date: 1959-05-18
Publication date: 1961-05-30
Anticipated expiration: 1978-05-30

Description

May 30, 1961 KENTARO TSUTSUMI 2,936,666

BRUSH ASSEMBLY UNITS Filed May 18, 1959 2 Sheets-Sheet 1 wa A ATTORNEYS May 30, 1961 KENTARO TSUTSUMI BRUSH ASSEMBLY UNITS Filed May 18, 1959 I Fab.

2 Sheets-Sheet 2 INVENTOR.

Kflv TARU 7 1/7 ATTORNEYS.

United States Patent BRUSH ASSEMBLY UNITS Kentaro Tsutsumi, Auburndale, Mass., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed May 18, 1959, Set. No. 814,120

9 Claims. (Cl. 310-247) This invention relates to brush assembly units by which an electrically conducting brush is mounted to yieldingly and resiliently press against a slip ring, commutator or other conductor surface with which it is relatively movable.

Objects of the invention are to provide a brush mounting which can be of a small size to match precision slip ring assemblies, which will have high current-carrying capacity, low friction, low contact resistance, long life, simple connections to electrical leads, ease of manufacture, assembly and installation, and which will be relatively simple, compact, practical, durable and inexpensive.

Other objects and advantages will be apparent from the following description of an embodiment of the in vention and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawing:

Fig. 1 is a longitudinal, sectional elevation of a unit constructed in accordance with this invention, but with the brush holder unsectioned;

Fig. 2 is an end elevation of the same;

Fig. 3 is an end elevation of the same with the brush holder removed, as viewed along the line 33 of Fig. 1;

Fig. 4 is a side elevation of the complete unit;

Figs. 5 and 6 are side elevation and plan respectively of one step in the manufacture of the volute spring and the attachment of its small end to the brush holder;

Fig. 7 is a side elevation of the volute spring at a later step in its manufacture; and

Fig. 8 is a plan of the complete volute spring as attached to the brush holder.

In the illustrated embodiment of the invention, the unit includes a tubular or hollow housing or casing 1 of metal, having its main part of a deep cup-shape that is closed at the open end of the cup by a metallic member 2. The end of the casing which is closed by member 2 has an external peripheral flange 3 encircling the open end and within which member 2 is received and fixed, such as by welding or soldering. The end wall 4 of the casing that corresponds to the bottom of the cup, has a slot 5 extending diametrically across its exterior face for a depth at least equal to the thickness of the end wall, which provides an aperture through that end wall from face to face.

A brush holder 6 extends endwise of itself through such aperture, and within the casing it has a head or flange 7 that slides in the casing and is guided thereby for endwise reciprocation of holder 6 in the slot 5. The inner end 8 of the holder 6 beyound the flange 7 is a stem which extends nearly to but terminates short of the opposite end of the casing. The end closure 2 on its inner face has a projecting tongue 9 with a deep recess 10 in its end face in which recess the inner free end of the stem 8 slides and is guided thereby. There is ample clearance between the free end of the stem 8 and the bottom of the recess 10 to enable substantial reciprocation of the stem 8 in recess 10 without the stem leaving that recess. The flange 7 limits reciprocation of the holder 6 in a direction out of the casing, and the inner end or bottom of recess 10 limits reciprocation of the holder 6 in the opposite direction.

A brush 11 of any suitable material, such as of silvergraphite for example, is secured in the outer free end of the holder 6, so as to form an endwise extension thereof for contact with a slip ring or commutation whose relative position is shown by the dash line 12 in Fig. l. Silver-graphite brushes are disclosed, for example, in US. Patent #2,418,812.

Within the casing 1 and surrounding the stem 8 is a compression spring 13 which is attached, such as by soldering, at one end to the stem 8 near the flange 7, and at its other end to the casing 1 near the closure 2. This spring 13 is under compression as installed, so as to always urge the holder 6 in an outward direction until flange 7 abuts the end of the casing. This spring is preferably a volute spring surrounding the stem 8 and with its smaller diameter end soldered or otherwise fixed to the stem 8 near the flange 7. The larger diameter end of the spring is soldered or otherwise fixed to the inner Wall of the casing as at 14, near the closure 2.

The closure 2 has a lug 15 extending from its outer face axially of the casing, to which lug a suitable circuit conductor such as a spring loaded socket wire terminal may be detachably connected. The closure 2 is attached to the casing and soldered in closed position around its periphery after the brush holder and spring have been inserted into the casing and the larger diameter end of the spring soldered to the casing.

The holder 6, where it passes through the slot 5 in the end wall of the casing, may be formed of a cylindrical rod, but with parallel, opposite flat faces 16 formed thereon to fit slidingly the opposite side Walls of the slot 5. This prevents rotation of the brush holder in the casing without limiting its sliding action in the slot. The slot is easily formed by merely milling it across the end face of the casing for a depth at least equal to the thickness of that end wall of the casing. The sliding engagement of the cylindrical flange 7 with the interior wall of the casing guides the holder in its reciprocations.

The volute spring 13 is formed of a flat metal ribbon 17 to give maximum current carrying capacity. Its manufacture is illustrated in Figs. 5-8 wherein a flat metal ribbon 17 of flexible resilient metal, such as shim stock brass, has one end soldered to the stem 8 near flange 7 as shown in Figs. 5 and 6. Then the ribbon 17 is wound spirally on the stem as shown in Fig. 7, and stretched endwise, as shown in Fig. 8.

The flange 3 of the casing has a flat area 18 (Fig. 2) which serves as a guide in aligning the brush holder unit with its mating ring, not shown, so that the unit may be easily and quickly mounted in or detached from its holder assembly (not shown), with the brush 11 always properly positioned with respect to a slip ring or commutator against which it abuts in use. This design permits easy and quick installation and removal of each individual cartridge assembly. The brush is preferably of silvergraphite because such material has a low constant contact resistance, high current carrying capacity, long life and low friction. The support of the brush holder 6 at both of its ends, provides accuracy of alignment of the brush.

The volute spring serves both as a spring loading member and a current carrying member, and with its fiat load deflection curve, when used in this unit, tends to maintain a constant pressure of the brush tip against an eccentric or other mating slip ring, or against a commutator. The constant spring pressure is obtained with the use of a large cross section of the spring, which in turn has a high current-carrying capacity. This model of unit has carried a current of ten amperes satisfactorily and its maximum current-carrying capacity appears to be much greater, The spring pressure of the volute spring 13 can be adjusted by varying the free length of thespring.

It willbe understood. that various changes in the details, materials and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. A brush assembly unit comprising a hollow housing having an aperture in one end wall thereof, a brush holder extending through and sliding in said aperture into said housing and there having a head which by engagement with said one end wall limits endwise movement of the holder in a direction out of the casing, and beyond said head a stern, a brush carried by the outer end of said holder, the interior of said housing having means for guiding said stem during reciprocation of said holder in saidaperture, and a volute spring in said housing surrounding said stem, with its small end fixed to said stem adjacent to said head, and its larger end fixed to the inner wall of said housing, and under compression to hold said head against said apertured end wall.

2.. The unit according to claim 1, wherein the end of said housing, opposite from said end with the aperture, has an exterior endwise extension formed to fit a spring loaded socket wire terminal.

3. The unit according to claim 1, wherein said aperture is a slot with opposite sides thereof fiat and parallel to oneanother, extending entirely across and from face to face through that apertured end wall, and the part of said holder which slides in said aperture is non-circular with opposite sides parallel to one another and conforming to and slidingly guided and held against rotation by the part of said apertured end wall which defines the sides of said slot, whereby said brush holder and brush will be held against angular rotation while slidable in said aperture.

4. The unit according to claim 1, wherein said stem guiding means is a tongue on the inner face of the end wall of said housing opposite from said apertured end, with a recess therein and extending in a direction length- Wise of the housing and open at the free end of the tongue in which recess the inner end of the stem is slidingly received through said open end, and guided for reciprocation as the brush holder moves in directions into and out of the housing.

5. The unit according to claim 1, wherein the end wall of said housing which is opposite from said apertured endwall has a stem exteriorv of the housing and extending;' approximately normal from thetouter face of that end wall for connection to a conductor.

6. A brush assembly unit comprising a cup-shaped, cylindrical, hollow casing having an aperture in its end wall forming the cup bottom, a brush holder within the aperture, slidingly guided by the casing end wall defining the aperture, and extending in both directions from that end wall, and with its inner end extending in a direction parallel to the axis of the hollow casing, a brush secured to and forming an extension of the outer end of said holder, said holder having a lateral flange within the casing and engaging with the apertured end wall for limiting removal of the holder from the casing, 21 voluteshaped spring of ribbon-like metal disposed within the casing and surrounding the inner end of said holder, with the smaller diameter end of the spring fixed to said holder near said lateral flange, and its larger diameter end fixed to the inner peripheral wall of said casing adjacent to the casing end opposite from said apertured end, said spring being continuously under compression. when within the casing, and a member fixed to the open end of said casing and closing it, and having on its inner face, and solely P within the casing, means slidingly guiding the inner end of said holder, and on its outer face means for connection to a conductor.

7. The brush assembly unit accordingv to claim 6, wherein said means slidingly guiding the inner end of said holder is a partof said member with a recess aligned with the inner end of said holder in which the said inner end is received and slides endwise of itself as the guidance.

8. The unit according to claim 6, wherein said casing has an external, peripheral, non-circular flange adjacent the end which is closed by said member, for aligning the casing in a position in which said brush on said holder will be aligned with its mating ring.

9. A brush assembly unit comprising a hollow, generally cylindrical casing having a slot with opposite, flat parallel side walls extending transversely across and through one end wall thereof, a brush holder extending through said slot into said casing and having opposite, parallel, flat side walls fitting and guided by said opposite slot side walls to prevent rotation of the holder while the holder is free to reciprocate endwise of itself in said slot, in directions into and out of the casing, the portion of said holder within said casing having a flange engageable with the inner face of said one end wall to limit movement of said holder in a direction outwardly of the casing, the other end wall of said casing having a tongue projecting from its inner face toward said one end wall and having therein a recess extending longitudinally of the tongue and open at the free end of the tongue, said holder having a stem, inwardly of the casing beyond said flange, slidingly received in said recess in said tongue and guided thereby in its reciprocations, a volute spring in said casing surrounding said stern and secured at its smaller end to said stern adjacent to said flange, and at its other and larger end secured to said casing adjacent said other end wall, and a brush held in the outer, free end of said holder, entirely exteriorly of said casing.

References'Cited in the file of this patent UNITED STATES PATENTS 738,747 Acly Sept. 15', 1903 1,318,713 Aalborg Oct. 14, 1919 FOREIGN PATENTS 118,520 Great Britain Sept. 5, 1918 447,417 Germany July 26, 1927