US2826082A - Variable cam and tracking mechanism - Google Patents

Description

March 11, 1958 J. VON RANSON VARIABLE CAM AND TRACKING MECHANISM Filed March 17, 1953 2 Sheets-Sheet l INVENTOR. 10 ra/v Kan/501v v M v M March 11, 1958 J. VON RANSON VARIABLE CAM AND TRACKING MECHANISM 2 Sheets-Sheet 2 Filed March 17, 1953 9M ill Josefvon Ranson, New Milford, onn., assignor to Kollsman Instrument Corporation,;Elmhurst, N. Y., a cor poration of New York.

Application March :17, 1953, Serial No.-342*,9351

4" Claims. (CL. 74-63) The presentinvention relates tocamming devices-having adjustable track surfacespresettable to providea desired lay-out or configuration andparticularly to' tracking mechanisms embodying such variable cams and arranged to adjust relative angular motionbetween two=rotating members.

In a wide'variety of automatic machines and electrical devices, it is necessary to coordinate relative motion between two rotating mechanisms, such as a drive shaft and a driven shaft. Coordinating devices for this purpose broadly embody variable cams to obtain thedesired flexibility in interrelating the motion between'the rotary mechanisms;

Accordingly, it is an object of the present invention to provide a novel cam track and follower arrangement arranged to facilitate adjustment-f the contour or configuration of the cam track.

In accordance with this aspect of the present invention, aflhigh. degreeof flexibility can be obtained byemploying elongated supporting members each independently movable and including extremities adjustable" to preset positions lying generally along a desired cam track contour or configuration. Heretofore it has been commonplace. to support relatively flexible tapes or bands on-the extremities of: the adjusted.v supporting members todefine the. cam track. The disadvantages of employing'a flexible tape or band are manifest, and often incompatible with the provision. of relatively simple, trouble-free mechanisms.

It is, therefore, another objectof the present invention toprovi-de a novel variable cam. highly flexible with respect to the track contours obtainable therewith,.yet relatively simple, sturdy and reliable.

A further object of the present invention is incorporation of a novelvariable cam of the-aforesaid character into a tracking mechanism forcoordinatingzvariation's in relative angular positions between" two rotating members inzaccordance with the cam contour. or configuration. As to this aspect of the present invention, it is 'a further aim to accomplish the desired coordination bypositive acting mechanisms which may be readily incorporated into portable instruments and the like where weight, size, and compactness are often prime considerations;

Many other objects, features and. advantages of the present invention will occur to those skilled' in the art as the description proceeds. In order to render understanding complete and lucid and further to comply with the statutes relating to the same and point outwhere: I have made a patentable advance in the arts and sciences, there-is shown and described the invention in all its detail inconnection with a specific embodiment thereof shown in the accompanying drawings wherein:

Figure 1 is an exploded perspective view showing; the novel variable cam of the present invention incorporated into a tracking mechanism embodying. features of the present invention.

Figure 2 is a top plan view of the variable cam when the various components ofFi'gure 1;

United States Patent 0 2,826,082 Patented Mar. 11, 1958 2. Figurei is a top plan view similiar to Figure *2 with parts omitted' for the 'sake' of clarity and showing the'details of thevariabl'e cam and the operative connections to drive and-driven members. VARIABLE CAM'AND TRACKING MECHANISM 5' Figured is a sectional-view taken substantiallyalong the line 4-4 of Figure 2 and looking "in the direction of the arrows;

Referring now to the drawings, there is shown a variable cam constructed in accordance with the'principlesofthe present invention as incorporated into a tracking device for producing variations in relative angular motion between two" rotarymechanisms, commonly a drive shaft and a driven shaft. Specifically, an upstanding base. or pedestal 10'carriesa horizontal supporting pl'ate 12.which is connected to the'base 10 by'clamp mechanismsl14disclosed and claimed in co-pending' application SerialN'o. 342,934; now Patent No. 2,766,502, filed concurrently herewith. Fixed to the supporting plate 12'isan upstandingcircularframe 16 terminating in an enlargedannular shoulder 18-.

Arranged along the generally circular path defined. by the'shoulder'18 of the frame 16 are a series of radially extending cam members 20 each in the form of an adjustment screw or bolt including a slotted. head 21" and a threaded body 22 projecting from the head and terminating in a flat end face or' extremity 24; Appropriately tapped holesare provided in the shoulder 18 for the respective adjustment screws 20 permitting independent adjustmentof the screws' relative to each other.

Asis apparent to those skilled inthe art, the inner extremities'24' of the screw membersZDI can be.arranged to define acam track of a desired contour'orv configuration. Thisarrangementis highly flexible but exhibits the shortcoming thata large number of screws 20. have. to be provided so that the gaps or interruptions between adjacent track-defining faces 24 are relatively small.

In accordance with the present invention, the spacing betweenadjacent adjustable screws 20 is not. critical and it is not necessary to provide a' flexible tape or the like interconnected between the respective screws. Specifically, a composite cam'follower 26, seen best in Figure l, is'adapted to ride along the cam track defined by the end faces 24 in a smooth and continuous manner even though the cam track itself isinterrupted at spacedintervals between adjacent screws. Specifically, the composite follower 26 inc1udes a'cam'roller 28 formed with a circumferential guideway 30 in the peripheral bearing, surface which normally would ride against the cam. track.v Surrounding the cam roller' 28 is a cam ring 32 which. is interposed between the cam roller 28 and the cam track. The ring 32 acts as' a floating slip member or tire and presents a' continuous and uninterrupted cam surfaceto the cam roller 28. The bearing portion of the, ring 32 which is interposed between thecam roller 28 and'tliercam track always remains substantiallytangential to the. roller and the track as the roller moves therearound.

The cam ring 32 includes an angul'arbody part 34 serving as a tire and commensurate in height with. the. cam roller 30 and an inwardly projecting flange or ledge 36 substantially normal to the angular or ring-like body 34. This flange is adapted to be conformably received. within the guideway 30 of the cam roller 28 torprecl'ude. lateral displacement. of the cam ring 32 relative to the'roller. 28. It is to be noted that the ledge or flange. 36 and the bounding walls' of the guideway 30 provide interengaging guide means, yet permit the requisite floating action. be.- tween the cam roller and the cam ring.

The composite follower 26 forms a partof a mechanical linkage system. which interconnects two rotary mechanisms arranged to translate motion of" the follower. along the cam contour defined by the adjustable screws 20 into shaft.

asaaosa changes in relative angular position of the two rotary mechanisms.

In the illustrative embodiment, a drive shaft 40 projects above the base and terminates at a level adjacent the adjustable screws 20. Journaled on the drive shaft is a driven rotary mechanism, designated by the reference numeral 42, which will be subsequently described in detail and is to be coordinated to the movement of the Overlying the driven rotary mechanism 42 is a segmental drive plate 44 provided with a suitable bore 46 for the extension therethrough of the drive shaft 49 which is keyed to the plate 44.

In the illustrative embodiment, and as best seen in.

Figure l, the plate 44 is provided with a slot 48 communicating with the bore 46 and defining a clamping part 50. Traversing the clamping part 50 is a tapped hole 52 adapted to receive a lock bolt 54, the bolt being extensible into the threaded opening 52 and thereupon into the plate proper to key the shaft 40 to the drive plate 44. Integral with the segmental drive plate is a bifurcated extension 56 including superposed legs 58, 60.

The driven mechanism 42 includes a circular disc or body 62 and a superposed member or arm 64 fixed over the disc 62 by screws 66. The discs 62 and the arm 64 are provided with a suitable opening 68 for the extension therethrough of the drive shaft 40, a bushing or sleeve 70 being interposed therebetween to permit free rotation of the driven rotary assembly 42 relative to the drive assembly of the shaft 40 and the segmental plate 44.

The cam follower 26 is supported by an arm 72 which is normally disposed above the disc or plate 62 and is bifurcated contiguous to the opposite ends thereof. Intermediate its ends the supporting arm 72 carries an upwardly projecting stub shaft 74 which supports the cam roller 28, the latter being fixed in position by means of a screw 76 received within a suitably tapped opening in the shaft 74. One end of the supporting arm 72 is connected to the drive assembly by a linkage 78 having one end pivoted by pin 80 to the supporting arm 72 and having the other end receivable between the legs 58, 60 of the bifurcated extension 56 and pivoted therebetween by a pin 82. The other end of the supporting arm 72 has an integral bifurcated extension 84 including superposed legs 86, 88 spaced apart to accommodate an enlarged head 90 formed adjacent one end of the driven arm 64 and the follower supporting arm 72 by a pin 92 receivable within openings within the superposed legs 86, 88 of the bifurcated extension 34 and in an aligned bore 94 in the head 9t) of the driven arm 64.

In order to bias the cam follower 26 into engagement with the properly adjusted track defined by the cam members 20, a spring 96 is interconnected between an integral ear 98 on the driven arm 64 and a depending pin 100 on the drive plate 44. As best seen in Figure 2, the spring 96 tends to urge the drive plate 44 in a counterclockwise direction carrying one end of the follower supporting arm 72 toward the cam track, the spring further tending to urge the driven arm in the clockwise direction carrying the other end of the follower supporting arm 72 to the desired position wherein the cam follower rides along the cam track.

In actual use, if the cam track defining members or screws are adjusted so that their inner extremities 24 are all equidistant from their common center, namely the axis of the drive shaft 40, the track for the cam follower 32 will be circular. This will result in the elements of the mechanical linkages provided by the plate 44, the connecting linkage 78, the supporting arm 72 and the driven arm 64 remaining in the same relative position with respect to each other, and there will be no variations in the angular displacement of the driven and driving units.

If adjustment of the cam members is selected so that the inner extremities 24 are not equidistant from the axis of the drive shaft 40, the extremities 24 will define a configuration deviating from a perfect circle and prescribing the desired motion for the cam roller 28 which follows the track via the cushioning ring or tire 32.

It is to be expressly understood that even though the shaft 40 has been described as the drive mechanism, while the disc 62 and the member 64 supported thereby as the driven mechanism, the drive could be applied to the disc 62 and the shaft 40 serve as the driven member.

In the foregoing I have described my invention solely in conne tion with specific illustrative embodiments thereof. Since many variations and modifications of my invention will now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosures herein contained but only by the appended claims.

I claim:

1. A device for producing variations in the relative angular motion between two rotary mechanisms comprising a generally circular frame, a series of co-planar cam members arranged at spaced locations along and radially of said circular frame, said cam members being independently mounted for radial movement into adjusted positions and including end faces cooperating in said adjusted positions to define a periodically interrupted cam track of predetermined contour, mechanical linkages interconnected between said two rotary mechanisms including a cam roller adapted to move along said cam track for translating said predetermined contour into changes in the relative angular positions of said two rotary mechanisms, and a rigid cam ring larger in diameter than said cam roller and interposed between said cam roller and said cam track, said cam ring being successively arranged tangentially of said cam roller and said cam track and presenting a continuous cam surface to said cam roller.

2. A tracking mechanism comprising a drive member movable about an axis, a driven member movable about said axis, and means coordinating relative angular motion between said drive and driven members, said means including a series of co-planar cam members arranged radially of said axis and cooperating to define a periodically interrupted cam track of predetermined contour, a supporting arm, a cam roller pivoted on said supporting arm co-planar with said cam track and adapted to move therealong, a rigid cam ring surrounding said cam roller and interposed between said cam roller and said cam track to present a continuous and uninterrupted camming surface to said cam roller, linkage means pivotally interconnecting one end of said supporting arm and said drive member, linkage means pivotally interconnecting the other end of said supporting arm and said driven member, and resilient means operatively connected to said drive and driven members and urging the assembly of said cam roller and ring into engagement with said cam track.

3. A tracking mechanism comprising a drive member movable about an axis, a driven member movable about said axis, and means coordinating relative angular motion between said drive and driven members, said means including a series of cam members arranged radially of said axis and cooperating to define a cam track of predetermined contour, a supporting arm, a cam roller pivoted on said supporting arm co-planar with said cam track and adapted to move therealong, a rigid cam ring surrounding said cam roller and interposed between said cam roller and said cam track to present a continuous and uninterrupted eamming surface to said cam roller, linkage means pivotally interconnecting the opposite ends of said supporting arm with said drive and driven members, resilient means operatively connected to said drive and driven members and urging the assembly of said cam roller and ring into engagement with said cam track, and inter-engaging means on said cam roller and said cam ring for guiding said cam ring against lateral displacement from the interposed position.

4. A variable cam comprising a plurality of radially extending cam members supported in eo-p'lanar relation to References Cited in the file of this patent define a cam track of predetermined configuration, a cam UNITED STATES PATENTS roller adapted to move along said cam track, and a rigid cam ring surrounding said cam roller and interposed g g between said roller and said cam track; said cam ring 5 2414134 I 1947 having a diameter greater than the cam roller and less 2514420 g 3 1950 than the smallest transverse diametric dimension of said 2589852 figg 1952 cam track; sa1d cam nng rolling freely between Said 2,590,287 Brellsford Mar 25, 1952 cam roller and said cam track, and providing an increased diameter bearing surface between said cam roller and 10 said cam track.

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