US3504146A - Wear limiting adjustable brush means for a rotary drum encoder - Google Patents

Description

March 31, 1970 p, 1 WAZNYS ET AL 3,504,146

WEAR LIMITING ADJUSTABLE BRUSH MEANS FOR A ROTARY DRUM ENCODER Filed May 28, 1968 2 Sheets-Sheet 1 fr 77 fz /f /05 7 :1r-:1111: /o Uf?, f ma n3 v n 4 /X/ Fwd Marh 31,`197`o v R'JMAVZNYS mL 3,504,146

WEAR LIMITIG ADJUSTABLE BRUSH MEANS FOR A ROTARY DRUM ENCODER v Filed May 2a, 1968 2 sheets-sheet 2 United States Patent O 3,504,146 WEAR LIMITING ADJUSTABLE BRUSH MEANS FOR A ROTARY DRUM ENCODER Peter J. Waznys, Richmond Hill, N.Y., and John A.

Garrido, Englishtown, NJ., assignors to Collectron Corporation, New York, N.Y., a corporation of New York Filed May 28, 1968, Ser. No. 732,581 Int. Cl. H01h 9/08 U.S. Cl. 200--166 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to the eld of rotary drum type encoders of the class disclosed in our co-pending application, Ser. No. 660,252; filed Aug. 14, 1967, entitled Multi-Speed Encoder, and assigned to the same assignee as the instant application.

An object of the invention lies in the provision of an improved brush structure in which the variation from an initial adjustment due to Wear of the contacting surfaces thereof is maintained at a minimum.

Yet another object of the invention lies in the provision of an improved encoder of the class described, in which the individual brush elements may be conveniently replaced as required.

A further object of the invention lies in the provision of improved encoder construction of the class described in which initial adjustment of the component parts thereof, during assembly is materially facilitated, as contrasted with prior art constructions.

A further object of the invention lies in the provision of an improved encoder construction possessed of the above enumerated advantages, in which the cost ofl fabrication may be of a reasonable order, directly comparable with existing prior art devices, thereby permitting consequent wide sale, distribution and use.

These objects, as Well as other incidental ends and advantages, will more fully appear during the progress of the following disclosure, and be pointed out in the appended claims.

In the drawings, to which reference will be made in the specification, similar reference characters have been employed to designate corresponding parts throughout the several views.

FIGURE 1 is a central longitudinal sectional view of an embodiment of the invention.

FIGURE 2 is a fragmentary plan view shown, one of the brush holding tab members comprising a part of the embodiment.

FIGURE 3 is a side elevational view of a tab element.

FIGURE 4 is a fragmentary end elevational view thereof, as seen from the plane 4 4 in FIGURE 3.

FIGURE 5 is a transverse sectional view as seen from the plane 5 5 in FIGURE 1.

FIGURE 6 is a fragmentary sectional View as seen from the plane 6 6 in FIGURE 1.

FIGURE 7 is a view in elevation as seen from the plane 7 7 in FIGURE 6, with an outer cover element removed for purposes of clarity.

In accordance with the invention, the device, gener- 3,504,146 Patented Mar. 31, 1970 lCC ally indicated by reference character 10 (FIGURE 1), comprises broadly: An outer casing element 11, a motion input shaft element 12, a reduction element 13, a drum element 14, and a brush element 15.

The outer casing 11 includes a primary shell 20 preferably formed as a machined casting, and including an end wall 21, a cylindrical wall 22, and a second end wall 23. Overlying the outer surface of the cylindrical wall 22 is a cover 24.

The end wall 21 is bounded by an outer surface 25, and an inner surface 26, between which extend a pair of radially disposed bores 27 and 28 which support pins 29 and 30, respectively for mounting in fixed relation a part of the reduction element 13. A centrally disposed bore 31 includes a counter bore portion 32 which forms a seat for a bearing 33.

The cylindrical wall 22 includes an inner surface 35, and an outer surface 36 which supports a plurality of brush support elements 37 (see FIGURES 6 and 7) between rst and second flange portions 39 and 40` which support the cover 24, as is Well known in the art.

The end wall 23 is preferably formed as a separate piece, and includes an outer surface 43 and an inner surface 44. A recess 45 supports a bearing 46 aligned with the bearing 33. An annular rabbet 47 permits engagement with the free end of the cylindrical wall 22. A cylindrical projection 48 supports lead wires 49 on an outer surface thereof, and provides a threaded bore (not shown) by which the cover element 24 is attached by screw means.

The cover 24 may be formed as a metallic drawing, and includes an end wall member 54 and an integral cylindrical Wall member 55. The end wall member includes an outer surface 56 and an inner surface 57, and includes a plurality of openings 58 for passage of lead wires 49. A central opening 59 passes the screw 50 which engages in the above mentioned threaded bore in the cylindrical projection 48. The cylindrical wall member 55 includes surface 61, and an inner surface 63 which engages the flanges 39 and 40.

The 4motion input shaft element 12 includes a shaft member 66 supported in bearings 33 and 46 and mounting a radially extending wave generator member 67 having first and second lobes 68 and `69, each mounting a bearing member as at 70l and 71. Inner bearing members 72 and 73 support the drum element 14 upon the shaft element 12 for relative rotation therebetween.

The reduction element 13 eliminates the use of conventional gear trains, and includes a flexible spline -member 76 cooperating with a iixed spline member 77. The flexible spline members 76 is formed of resilient synthetic resinous material, and is bounded by a smooth inner surface 79 and a toothed outer surface 80 adapted to engage the toothed inner surface 81 of the fixed Spline member 77 Openings 83l and -84 engage the pins 29 and 30 to x the spline member 77 with respect to the casing element 11.

The operation of the reduction element will be best understood from the consideration of FIGURE 5, wherein with rotation ofthe shaft element 12, the wave generating lobes v68 and 69 will progressively deform the flexible spline member 76 as it engages the fixed spline member 77, and with each revolution of the shaft member 66, the drum element 14 which mounts the flexible spline member 76 will rotate an angular distance equivalent to the difference in the number of teeth on the members 77 and 76 as compared with the number of teeth on the fixed spline member.

The drum element 14 is generally similar to that disclosed in the above mentioned co-pending application, Ser. No. 660,252; and includes a core member 87 forming a central bore 88 for the engagement of the shaft member 66, and locking means 89 for fixing the core 87 upon the shaft, which structure is both disclosed and claimed in said application. The outer surface 96 of the core member 87 is cylindrical in configuration, and mounts an insulative sleeve 91 which in turn mounts electrically conductive rings 92.

The brus'h element 15 includes a plurality of arcuately shaped generally rectangular support Imembers 94 which are mounted on the outer surface of the cylindrical wall 22. As best seen in FIGURES 1 and 6, the inner surface 96 thereof is provided with an arcuately shaped tongue 97 engaging a correspondingly shaped slot 98- in the wall 22,

whereby the former is adjustable through an arcuate path v of motion with respect to the latter. Cementitious means 99 engages a slot 100, preferably extending over an arcuate distance of approximately degrees. An opening 101 provides for the projection of a conductive brush structure, which bears upon the conductive rings 92. A

plurality of channel forming members 103 define a plurality of interstices 104, each one accommodating a wiper tab assembly 105 (FIGURES 2 and 3). The assemblies 105 are substantially Similar, each including a thin metal interface 106 bounded by an upper surface |107, a lower .f

The wiper blades 116, are identical in construction,

and as will more fully appear, are adapted to maintain an initial adjustment within Very close limits, irrespective of the amount of wear occurring upon the surface in direct ,contact with the drum element 14. As best seen in the above figures, each wiper blade is formed from a single length of wire, and includes a iirst member 117, a first end segment 118 thereof being Welded to the interface 106. The segment 118 is interconnected by a bent portion to an angularly disposed portion 120, in turn connected by a right angle bend to an upwardly facing loop portion 121 which lies in a plane substantially perpendicular to the surface of the drum element 14 which it contacts, which plane is perpendicular to the direction of surface movement at that point. The opposite end of the loop -121 is connected by a right angle bend 122 to an angularly disposed portion 123 parallel to the portion 120, in turn connected through a bend portion 124 and welded segment 124a. The segment 124a connects with a small 180 degree loop 125 to a member 126 which is substantially identical to the rst member 117, and which terminates in a second end 127. The member 126 includes a second upwardly facing loop 128 lying in a plane coplanar with that of the loop 121.

With continued use, wear will occur on the loops 121 and 128. This wear will occur on the lower surfaces of the loops which are in tangential contact with the drum element, but from a consideration of FIGURES 4 and 6, it will be apparent that at no point can the total wear cause a contact width greater than the dia-meter of the wire from which the wiper blade is made, and with increased wear, `as the theoretical point contact enlarges to an ovoid surface, the pressure is distributed over a greater area, so that continued use results in ever lessening wear.

We wish it to be understood that We do not consider the invention limited to the precise details of structure shown and set forth in. this specification, for obvious modifications will occur to those skilled in the art to which the invention pertains,

We claim; i

1. Improved brush block construction for use with a shaft-driven encoder having an outer housing and an electrically conductive drum arranged for rotation therein, said housing having openings therein for the penetration of bnush means therethrough to contact said drum, said construction comprising: an arcuately-shaped support member of generally rectangular conguration and having a first surface including an arcuately-shaped tongue extending .outwardly thereof, there being an arcuatelyshaped slot disposed in an outer surface of said housing, whereby said support member is rectilinearly adjustable along an arcuate path with respect to said housing; said support memer including a plurality of channel-,forming members defining a plurality of interstices therebetween, and a plurality of wiper tab assemblies slidably positioned within said interstices; whereby said support member may be slidably adjustable with respect to said housing, and said wiper tab assemblies may be individually adjustable with respect to each other upon said support member.

2. Structure in accordance with claim 1, in which the wiper tab assemblies are retained in position by frictional means.

3. Structure in accordance with claim 1, including Cementitious means for retaining said tab assemblies in given adjustment.

4. In a combination current-conducting brush and a contacting conductive surface in relatively movable relation thereto along a principal axis of movement, said brush being formed of resiliently deformable round wire, and having means for supporting said wire substantially at one end thereof, the improvement comprising: said wire including a flexible segment having a first relatively fixed end, and a second relatively free end: said flexible segment having a principal axis substantially parallel to said principal axis of movement, said free end forming a looped segment lying in a plane, said plane interconnecting said principal axis of movement substantially at a right angle, whereby when said looped segment executes relative movement with respect to said conductive surface, the elfect of maximum possible wear on said looped segment is limited to the shifting of the contactl point along said principal axis of movement to a degree equal to the radius of a cross-section of said wire.

5. Structure in accordance with claim 4, said brush construction including a pair of flexible segments, each fixed at one end thereof, and each interconnecting one end of said loop segment.

6. Structure in accordance with claim 5, including a plurality of pairs of flexible segments, each pair interconnecting a looped segment.

7. Structure in accordance with claim 6, in which said looped segments lie in a common plane.

References Cited UNITED STATES PATENTS 1,399,492 12/ 1921 Krantz.

2,401,419 6/1946 Ford.

2,454,788 11/1948 Frese.

2,723,319 11/1955 Sebring et al. 20G-25 2,853,563 9/1958 Bole et al. 200-8 3,243,529 3/ 1966 Behringer.

FOREIGN PATENTS 1,261,331 12/1961 France.

ROBERT K. SCHAEFER, `Primary Examiner ROBERT A. VANDERHYE, Assistant Examiner Us. 01. XR.

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