US 2239931 A
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April 29, 1.941. R. s. PRESCOTT VIBRATORY MOTOR Filld July 31, 1939 INVENTbR BY f 0f IATTZNQEY Patented Apr. 29, 1941 UNITED STATES PATENT OFFICE VIBBATORY MOTOR mam s. rnesoott, Brookline, Mus, assignor to Gillottmw'oty M (loinpany, Boston, Mass, I, of Delaware .App llea tion July 31, ms, Serial No. 287,494
This invention relates to vibratory motors employing an electro-magnet-arralize to be energized by an alternating current correspondin in cycle substantially to half the uatllral frequency of the armature sothsttheQlatter is maintained in vibration with, theegpenditure of minimum energy. In one aspect .thefpresent invention consists in an improved motor of this type having certain novelcharactel'istics which particularly adapt it for use in dry-shaving implements or other compact installations .where economy of space is an importantconsideration.
My invention is herein shown by way of illustration as embodied in a.dry-.=shave r having a movable cutter at one end. which it isdesired to vibrate transversely and insubstsntially. symmetrical relation to the longitudinal axis uncenter line of the implement. .l'for economyot space and in order to conform tn the general contour of the dry shaver it is desirable tolocate the electro-magnetic core of the.,motor in the longitudinal center line of the implement-and accordingly the armature or armatures must be located in offset relation to such center line.
An important object of, the present invention is to solve the problem of trausmittinghigh speed oscillation of small amplitude from anfarmaturc located in this unsymmetricalmanner to! 87mmetrically located vibrating arm or driven .memher, without the necessity of. pivots or parts which in such relationship areunsvoidably subjected to serious wear so that-the= implement becomes noisy and the accuracy oil'itsshearing action is impaired. Tothis end. an important feature of my invention consists ,in an arm supported for vibration or rocking t upon the frame by means ofsymmetrically disposed springs which accurately locate the arm, hold it normally in a predetermined initial position and by their flexing permit the desired vibration all. of course, without the employment of pivots or bearings. Another important feature of, the invention consists in co-operating members mounted for rocking movement about diflerent axes and having an operative connection which comshown in the accompanying drawing, in which- Fig. l is a view of the implement in front elevation showing the cover of the casing removed and a portion broken out of the head;
1 Fig. 2 is a view of the implement in side elev'ation with portions of the casing and head shown in cross-section; and
Fig. 315 a view in cross-section on the plane l--3 of Fig. 1.
The vibrating motor of my invention is herein shown as mounted within and enclosed by a holnently secured an elongated metal bed piece I? which carries the motor presently to be described. 'lj'he bed piece mergesat, its upper end into a me'tal block l3 conforming in contour to the curvature of the casing and shaped to supply one side of a socket in the end of the implement. The other side of the metal head is formed by a correspondingly shaped block it which is perniahently secured by dowels and screws to the block l3 and forms with the latter an open socket for the reception of the shearing head IS. The latter is'provided at its upper end with inturned flanges which are slotted to provide stationary transverse shearing teeth It. An elongated movable cutter i1 comprising a rectangular bar having two series of teeth formed in its upper face and co-operatively arranged with respect to the stationary teeth It is mounted for longitudinal reciprocation in the shaving head Ill and actua I by a resiliently mounted lever or arm I. which will be described more particularly hereinafter. The construction of the shearing memhers is no part of the present invention but may be conventional.
An electro-magnet 20 is permanently secured by rivets or otherwise to the lower end of the bed piece l2.
7 wound on a bobbin and surrounding a laminated It comprises an insulated coil core which is shaped to provide a central web portion and substantially flat transversely extending flanges above and below the coil of the electro-magnet 20. The parts described are, of course, the stationary parts of the motor.
.An armature bar is arranged. to vibrate on each side oi the electro-magnet 20 in the spaces provided by the overhanging upper and lower flanges of the magnet core. The right-hand armature bar 22 is connected at its upper end by screws to a spring leaf 2! which in turn is connected at its upper end to one end 01' the metallic head I of the casing by means of screws which are threaded into the ends of the head. The left-hand armature bar 24 is similarly connected and carried by a spring leaf 2! fastened to the left-hand end of the head of the casing. The springs 23 and 25 are so shaped and adjusted as to maintain their two armature bars initially or normally in a position slightly outside the contour of the flanges oi the core II. It will be understood that when the electro-magnet is energized by an electric current the magnetic iield thus created tends to vibrate the spring supported armature bars equally and oppositely toward and from each other and at each reversal of the current the armature bars spring apart. By properly shaping and mounting the armature bars these may be tuned for vibration in twice the natural cycle 01' the energizing alternating current. The balanced vibration secured in this manner produces the maximum physical movement of the armature with the expenditure of the least amount 01 energy possible.
The cutter actuating lever I8 is located and use in dry shaving implements which are to be used by those indifferent to the necessity for lubricating the moving parts or unable properly to eflect such lubrication.
Having thus disclosed my invention and described a preferred embodiment thereoi for illustrative purposes, but not in any limiting sense,
mounted for rocking movement upon the under or inner side of the metallic head ll-ll by a pair 0! flat curved springs 21. These supporting springs are bolted to the opposite sides of the lever ll slightly below -midposition -as shown in Fig. 1 and are then curved in opposite directions and attached to the under face oi the block ll. The springs 21 are flexible and well tempered so that the lever arm I! is well supported and accurately located and isii'ee to vibrate transversely about a ilxed axis while requiring only a very slight flexing oi the springs. The lower end of the actuating lever II is directly connected by means oi a transverse spring link 29 with the upper end oi the left-hand armature bar 24 and consequently, movement or the bar 24 is transmitted as a rapid vibration to the lever ll. Here again it will be noted that no rocking or oscillating parts are involved and that flexing oi the spring link II compensates for the movement which would ordinarily be required in a connecting link between the two such oscillating parts as the lever I I and the armature bar 14. Moreover, the construction described eliminates the necessity of immune any moving parts in the motor because itincludes no sliding or rotating parts. This is a very desirable feature of motors designed for oscillatory arm.
I claim as new and desire to secure by Letters Patent:
1. A vibratory motor comprising a frame having at one end a transversely extending head, an electro-magnet carried by the frame, flat springs secured to opposite ends of the head, armature bars disposed adjacent to opposite sides of the magnet, curved springs secured to the under face of the head, an arm supported for rocking movement by said curved springs. and a spring leaf extending transversely between one 0! the armature bars and the arm below its point oi connection with said springs.
2. In a dry shaver motor, the combination of a head and a cutter-actuating arm, with a pair oi oppositely curved leaf springs movably supporting saidarm upon the head, a stationary electro-magnet mounted in the shaver beyond the end of said arm, armaturesarranged to vibrate at either side of the magnet, springs on which said armatures are mounted, and a iiat pivotless spring directly connecting one of said armatures with said cutter-actuating arm.
3. In a dry shaver, a vibratory motor having a frame shaped to provide at one end a transversely extending support, an elongated electro-magnet carried by said frame, springs secured to the support, armature bars carried by said springs and disposed on opposite sides of the magnet, oppositely curved springs secured to the support, an arm mounted between said curved springs for rocking movement about an axis in line with the longitudinal axis of. said magnet, and a transverse spring connecting one armature bar with the spring mounted arm in a location between the magnet and said springs.
4. A dry shaver motor comprising a frame having at one end a support, an electro-magnet carried by the frame, springs secured to the support at separate points, armature bars carried by said springs and disposed upon opposite sides oi! the magnet, an oscillatory am having an independent spring connection with the support intermediate the separate points at which the armature bars springs are secured, and a pivotless link connecting one oi said armatures with said ROBERTS. ransco rr.