US2924800A - Miniaturized slip ring device - Google Patents

Description

Feb. 9, 1960 Filed April 25, 1957 W. M. SCARBOROUGH MINIATURIZED SLIP RING DEVICE 2 Sheets-Sheet l INVENTOR. WILLIAM M. SCARBOROUGH ATTORNEY Feb. 9, 1960 w. M. SCARBOROUGH 2,924,800

I MINIATURIZED SLIP RING DEVICE Filed April 25, 1957 2 Sheets-Sheet 2 SWAGED 380 II n u n Lnnnnnnnnnn II II II H |l\ fl| II II II II II II H II ll INVENTOR. WILLIAM M. SCARBOROUGH BY ciwi MW ATTORNEY United States Patent MINIATURIZED SLIP RING DEVICE William M. Scarborough, Whittier, Calif., assignor to North American Aviation, Inc.

7 Application April 25, 1957, Serial No. 655,128

Claims. (Cl. 339-5) This invention relates to electrical slip ring devices, and particularly to slip ring devices adapted to make continuous electrical connections for rotating apparatus.

Slip ring devices heretofore have tended to be bulky devices unadapted to miniaturization. A particularly difficult problem encountered is that of mounting a plurality of brushes in a confined area. A related problem is that'of providing a suitable brush member adapted to provide a good electrical connection but also being of a sizeand shape so as to cooperate with an improved brush mounting means.

Ease of serviceability is another feature in which prior art slip ring devices have been lacking. In a miniaturized slip ring device it is especially important that the brush and brush mounting members be easily removable for cleaning and replacement.

It is, therefore, an object of this invention to provide an electrical slip ring device adapted for miniaturiza tion.

It is another object of this invention to provide a slip ring device having improved brush and brush mounting members.

It is still another object of this invention to provide an electrical slip ring device having a low friction and low noise level.

A further object of this invention is to provide a slip ring device adapted for easy removability of the individual brush members.

It is another object of this invention to provide a slip ring device adapted for easy removability of a plurality of brush members simultaneously.

Briefly, in accordance with the present invention in a preferred form thereof an electrical slip ring device is provided having a plurality of slip rings and connecting brushes. A unique brush mounting means is employed wherein a plurality of brushes are mounted in a very small area. The brushes are adapted for mounting on individual terminal strips and these terminal strips in turn are mounted on the brush mounting means. The brushes and brush mounting means are designed so that both the individual brushes and also a plurality of brushes may be easily removed for cleaning or replacement.

A more thorough understanding of the invention may be obtained by a study of the following detailed description. In the drawings:

Fig. 1 illustrates a half sectioned view of a slip ring device constructed in accordance with this invention;

Fig. 2 illustrates a front view of a brush mounting means constructed in'accordance with this invention;

Fig. 3 illustrates a bottom view of the brush mounting means shown in Fig. 2;

Fig. 4 illustrates the brush and slip ring connection embodied in this invention, the brush mounting means being shown in a cross-sectional view taken on line 3-3 of Fig. 2;

Fig. 5 illustrates an individual brush member cons'tructedin accordance with this invention;

2,924,800 Patented Feb. 9, 1960 Fig. 6 illustrates a brush member mounted in its associated terminal strip as utilized in this invention; and

Fig. 7 is a sectional view of the slip ring device.

In the sectioned view of Fig. 1 is shown a slip ring device 10 having a base 11 and a vertically disposed shaft 12 mounted thereon by a plurality of screws 13. The inner race of a ball bearing 14 is mounted to the base of shaft 12 by a retaining ring 15. A substantially cylindrical insulator 16 is mounted on shaft 12 and retained by a threaded retaining nut 18 mating with threads 17 on the end of shaft 12. A plurality of insulating spacers 19 and interleaved slip rings 20a and 20b are mounted on the insulator 16, the insulating spacers 19 serving to insulate the slip rings from each other.

Shaft 12 is of hollow construction thereby permitting a plurality of conductive wires 21 to be mounted therein. Wires 21 have one end connected to a terminal board (not shown) and the other end attached to one of the slip rings 20a or 20b. Suitable holes 29 and 30 are respectively provided in both the shaft 12 and the insulator 16 for permitting the passage of the wires 21 therethrough.

A mounting frame 31, of substantially rectangular con-- struction, has opening 32 on all four of its longitudinal sides. End members 33a and 33b at the opposite ends of the mounting frame 31 are adapted for mounting the frame 31 on the base 11 and shaft 12. As shown in the sectional view of Fig. 1, end member 33a has formed therein a circular opening corresponding to the size of the outer race of ball bearing 14. A second ball bearing 34 has its outer race attached to the mounting frame 31 and its inner race attached to the shaft 11. Retaining ring 35 mounted on the opposite face 33b by a plurality of screws 36 retains the outer race of ball bearing 34 while threaded screw 37 engages corresponding threads of shaft 12 and retains the inner race of ball bearing 34. Thus the mounting frame 31 surrounds shaft 12 and is rotatably mounted on base 11 by means of ball bearings 14 and 34.

Brush blocks 38a and 38b are mounted upon opposite longitudinal faces of the mounting frame 31 by screws 39. Brush block 38a is shown in side and bottom views in Figs. 2 and 3 respectively and in cross-sectional view in Fig. 4. The block is preferably molded of an insulating material such as nylon and is provided with a plurality of T-shaped grooves 41 and hole pairs 42 as shown in Figs. 3 and 4. A plurality of corresponding T-shaped terminal strips 43 are mountable in grooves 41. As is shown in Figs. 1 and 3, the T-shaped terminal strips 43 have the same outside dimensions as the T-shaped grooves 41. The terminal strips 43 may therefore be retained in the brush blocks by friction between the strips and the grooves. Of course if deemed desirable a cover plate (not shown) made from a non-conductive material may be aflixed to each brush block so as to cover the several strips and further retain them in position. One end of the terminal strip 43 may be provided with a connecting terminal 44. Although the T-shaped slots and terminal strips permit an efficient utilization of space on the brush block any convenient shape may be used instead.

Fig. 5 illustrates an individual Wiper brush 40a. The brushes 40a and 40b shown in Fig. 1 may be of identical construction and are preferably formed from a resilient wire stock. A generally U-shaped Wiper brush has been found to give a good electrical connection between the brush and the slip ring and is also easily mounted on a terminal strip.

An individual brush assembly is illustrated in Fig. 6. This brush assembly comprises a brush 4011 (or 40b) and a terminal strip 43. The terminal strip 43 is preferably provided with a groove 50 into which the central portion of the U-shaped wiper brush 40a may be posiof the wiper brushes.

interleave brushes 40a and 40b when the brush blocks are attached to the mounting'frame 31 (as shown in Fig.

1). Brushes 40a and 40b are thereby positioned so as to contact respectively slip rings 20a and 20b. in a, direction generally tangential to the ring periphery. Thus, it Will be seen that each brush block need carry'only half of the total brushes necessary. This technique of staggering the brushes between the two brush blocks results in a maximum spacing of each individual wiper brush. As shown in Figs. 1 and 4, the wiper brushes 40a and 40b ride in grooves formed in the periphery of the slip. rings 20a and 2%. For minimum friction and low noise levels these grooves are preferably formedwith surfaces complementary to that of the arcuate surfaces The two arms of, the U-shaped,

brush engage substantially opposite portions of the; slip rings thereby insuring maximum electrical, conductivity regardless of the direction in which the mounting frame rotates on the base.

An indication of the miniaturization achievedby this invention is seen by the fact that the slip, ring shown in Fig. 1 is four times scale size. Thus, 44 slip ringv connections are possible in a slip ring device having a length in the order of 2 /2 inches. Although the brush mounting means illustrated in Fig. 1 is limited to brush blocks on two sides of the, mounting frame, it would-beentirely possible to locate brush blocks on all four sides of the mounting frame. Further miniaturization would be possible by using a frame having a shape which permits the mounting of additional blocks, e.g; a frame having a hexagonal cross section. Of course the brush assemblies must be mounted so that each is vertically displaced from the other in order to obtain interleaved wiper brushes. Otherwise, the physical size of the slip ring would be primarily dependent on the thickness of the slip rings and insulating spacers.

A further advantage of the brush mounting means disclosed in this invention is that individual brush assemblies or a plurality of brush assemblies may be easily and quickly removed from the slip ring device thereby facilitating routine maintenance and replacement of the wiper brushes when necessary. For this purpose bent portions 52 may be formed in the end portionsof the brushes 40a and 40b.

Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the appended claims.

I claim:

1. In a miniaturized electrical slip ring device a base assembly including a vertically disposed shaft, a plurality of conducting rings mounted coaxially on said shaft and insulated one from the other, a mounting frame surrounding said rings and rotatably mounted on said base assembly, said frame having a plurality of substantially open sides parallel to the axis of said shaft, a plurality of brush blocks removably mounted on said open sides of said frame, and a plurality of spaced conducting brush assemblies having portions contacting said slip rings and being removably mounted on each of said brush blocks whereby each of said brush assemblies is vertically displaced from every other brush assembly.

2. In an electrical slip ring device a base member, a

ing frame surrounding said ring and mounted on said base, a brush block of insulating material having front and back faces and being removably mounted on said frame, said brush block having a pair of holes formed therein passing completely through said block from said front to back face, a terminal strip removably mounted to the front face of said brush block, and a generally U-shaped Wiper brush having a central. portion andtwo arm portions, the central portion of said wiper brush being afi'ixed to said terminal strip, and said two arm portions positioned through, said pair of. holes in, said. brush block and contactingtwo portions of said conducting ring.

3. In combination in a miniaturized electrical slip ring device, a brush block. of insulatingmaterial having a plurality of interleaved T-shaped grooves therein, and a plurality of brush assemblies comprising T-shaped terminal strips fitting in each of said T-shaped grooves, said terminal strips having a groove therein, and a, plurality of resilient wiper brushes of, substantially U-form having a base portion secured'in each of said terminal.

strip grooves, whereby brush, mounting compactness is achieved together with easy removability of brush as:- semblies andbrushv blocks for-replacement.

'4. In a miniaturized electrical slip ring device av base assembly including a vertically disposed shaft, a plurality of conducting rings mounted, coaxially on said shaft'and insulated one from the other, a mounting. framesurrounding said rings and rotatably mounted on said base assembly, said frame havingia plurality of substantially open sides parallel to the axis of, said shaft, a. plurality of brush blocks of insulating material having. front and.

back faces and being removably. mounted on said. open sides of said frame, each of said brush blocks having.

a plurality of vertically spaced hole pairs therein'passing completely throughsaid block from said front to. back face, a plurality of terminal strips removably mounted upon the front face of said. brush block wherebyeach of said terminal strips is vertically displaced from every other terminal strip, and a plurality of generally U-shaped one of said terminal strips, and each of said two arm conducting ring mounted on said base member, a mount-.

portions positioned through, one of said hole pairsin said brush blocks and contacting two portions of one of said conducting rings.

5. In a miniaturized electrical slip ring' device a base assembly including a vertically disposed shaft, a plurality of conducting rings mounted coaxiallyon said shaft and insulated one from the other, a mounting frame rotatably mounted on said base assembly, a plurality of brush blocks formed from a non-conductive material and removably mounted on said mounting frame, each of said brush blocks having a front face molded so as to accept and retain a plurality of brush assemblies each comprising a terminal strip and a wiper brush,- said wiper brush extending completely through said brush block from the front face thereof to said conducting rings.-

References Cited in the file of this patent UNITEDSTATES PATENTS.

1,586,713 Sjolin .Iune 1, 1926 1,900,206 Silberstein ,Mar.,7, 1933 2,242,273 Taylerson May 20,1941 2,307,216 Graham Jan. 5, 1943 2,414,897 Rickrneyer Jan. 28, 1947 2,473,526 Hood et al June 21,1949 2,509,931 Krantz May 30,1950 2,550,578 McBerty Apr. 24,, 1951 2,572,956 Servis Oct. 30, 195.1.

FOREIGN PATENTS.

566,985 Great Britain Ianr23; 1945.

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