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Publication numberUS3296468 A
Publication typeGrant
Publication dateJan 3, 1967
Filing dateJan 28, 1964
Priority dateFeb 2, 1963
Also published asDE1463988A1
Publication numberUS 3296468 A, US 3296468A, US-A-3296468, US3296468 A, US3296468A
InventorsTownshend Rochard Chambrey
Original AssigneeMorphy Richards Cray Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Vibrator motors for electric dry shavers
US 3296468 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

1967 R. c. TOWNSHEND 3,296,463

VIBRA'IOR MOTORS FOR ELECTRIC DRY SHAVERS Filed Jan. 28, 1964 United States Patent 3,296,468 VIBRATOR MOTORS FOR ELECTRIC DRY SHAVERS Roehard Chambrey Townshend, Sevenoaks, Kent, England, assignor to Morphy-Richards (Cray) Limited, St. Mary Cray, Kent, England, a company of Great Britain Filed Jan. 28, 1964, Ser. No. 340,597 Claims priority, application Great Britain, Feb. 2, 1963, 4,350/ 63 8 Claims. (Cl. 310-29) This invention relates to vibrator motors for electric dry shavers and other electro-mechanical devices.

Known forms of electric dry shavers have one or more reciprocating cutters driven by a vibrator motor. The vibrator motor consists of an electro-magnet more or less rigidly fixed to the case and one ortwo oscillating arma tures connected mechanically to the cutters.

A disadvantage of known forms of vibrator motor with one armature is that movement of the armature reacts on the case and sets up a vibration which is transmitted to the hand of the user.

In order to reduce the vibration of the case and make it more comfortable to hold in the hand a known form of vibrator motor has two armatures, the cutter being mechanically connected to one of them. The two armature assemblies have substantially equal polar moments of inertia about their respective pivots and are constrained by a mechanical linkage to move substantially equally in anti phase. The result is that the reactions on the case caused by the oscillations of the twoarmature assemblies substantially balance each other out and only the small residual difference is transmitted to the hand of the user.

According to the present invention there is provided -a vibrator motor comprising an electro-magnet assembly, an armature assembly, pivotal mountings for both said electro-magnet assembly and said armature assembly, .mechanical coupling means from said electro-magnet assembly to said armature assembly to cause said electromagnet assembly and said armature assembly to move in anti-phase about their pivotal mountings the one with respect to the other under the constraint of said mechanical means when said electro-magnet is energized in such a way that the relative angular movements of said armature assembly and said electro-magnet assembly are predetermined by said mechanical means. 7 7

One form of shaver vibrator motor according to the present invention has the electro-magnet and the armature assembly including the cutter pivoted about their respective centres of gravity. Normally the polar moment of inertia of the armature assembly about its pivot is much less than that of the electro-magnet. A mechanical linkage is arranged so that the ratio between the angular movements of the armature assembly and the electromagnet is the "same as the ratio between the moments of polar inertia about their pivotal axes of the electro-magnet and the armature assembly. The result is that the reactions on the case caused by the oscillations of the electro-magnet and the armature assembly substantially balance each other out, and only the small residual dif ference is transmitted to the hand of the user.

For practical reasons it may not be convenient to pivot the armature assembly and the electro-magnet about their respective centres of gravity. However, with their respective pivotal mounting suitably located it is still pos sible to attain a good degree of balance and this system is the one most likely to be required in practice.

In order that the present invention may be clearly understood and readily carried into effect it will now be described with reference to the accompanying drawings, in which:

FIGURES 1 and 2 illustrate vibrator motors for an 'ice electric dry shaver according to two examples of the present invention.

The electro-magnet assembly of the vibrator motor shown in FIGURE 1 has a laminated and U-shaped magnetic core 1, on the limbs of which are mounted two coils 2. The armature assembly has the armature magnetic laminations 3 adjacent to the poles of the electromagnet and is mechanically connected to a cutter represented by the rectangle 4. The cutter operates in conjunction with a shear plate 32.

The armature is pivotally mounted on 'a frame 5 by means of a pin 6 projecting from the frame 5. The electro-magnet is mounted rigidly on the frame 5.

Fixed to the electro-magnet is an Lbeam 7 made of insulating material. A metal pin 8 passes through the I-beam 7, and is fixed to it, being insulated within the web from the electro-magnet coils, and projects beyond the flange faces of the I-beam 7 and beyond the frame 5. The ends of the pin 8 are mounted in bearing fixed to the case 31 of the shaver. Thus the frame 5 and all parts mounted on it can pivot in the case on the pin 8.

The armature is also mechanically connected to the case by the bridge piece 10 which has knife edges that bear in V-grooves. One V-groove is moulded in the case at 11 and the other is formed in the porous sintered metal bush 12. The cantilever spring 13 has a fiat bottomed depression formed in it which allows limited movement of a small ball bearing. The spring 13 forces the ball bearing against the bridge piece 10 so locating the bridge piece knife edges at the bottom of their respective V-grooves.

The springs 14 hear at their outer ends against lugs 15 integral with the frame 5. At their inner ends they bear against the armature so that its static equilibrium position is at approximately the mean of its normal operative travel. Approximately the greatest amplitude of oscillation is normally obtained with the equilibirium position arranged so that the corners of the armature and the electro-magnet laminations are adjacent, as shown in the figure.

Examination of FIGURE 1 shows that for small angles of movement of the armature the right hand knife edge of the bridge piece is virtually stationary relative to the case. This means that relative to the case the armature virtually rotates about the bridge piece right hand knife edge while the electro-magnet rotates on the pin 8. It is also clear that for small angular movements of the armature the angular velocity ratio relative to the case between movements of the electro-magnet and the armature is virtually equal to the ratio between the distance from the bridge piece right hand knife edge to the centre of the pin 6 and the distance between the centres of the pins 6 and 8.

The shaver vibrator motor illustrated in FIGURE 1 has the centres of gravity of the electro-magnet and armature assemblies some distance below their respective pivots, described above, relative to the case. This corresponds to the general conditions referred to in the preamble as being the one most likely to be required to practice.

For the shaver vibrator motor illustrated in FIGURE 1 the conditions for balance within the terms of the present invention may conveniently be calculated as described below for small angles of movement. Some slight adjustments may be desirable in practice to obtain'the best results with the normal angular movement of the armature.

The electro rnagnet is assumed to have unit angular acceleration and moments are taken about the two pivot points described above relative to the case for the inertial reactive torques exerted by the disparate moving parts. Normal use is made of the well known parallel axes theorem. Due account is taken of the condition that the shaver cutter reciprocates without rotation while the other major moving components oscillate about their pivoted axes. Due account is also taken of the velocity ratios existing between the moving components.

It is important to note that for the purposes of these particular calculations neither pivot point is assumed to transmit any force at all.

The two equations obtained may conveniently be manipulated by assuming figures for all the possible variables except the two distances controlling the angular velocity ratio. Then, for each of the two equations, the value of one distance for given values of the other may be plotted an a graph. The point where the two lines cross gives the solution.

FIGURE 2 illustrates a layout which is a modification of that shown in FIGURE 1, but which is similar in principle to that shown therein. It illustratestypical variations which lie within the scope of the present invention.

The electro-magnet assembly of the vibrator motor shown in FIGURE 2 has a laminated and U-shaped magnetic core 16, on the limbs of which are mounted two coils 17. The armature assembly has the armature magnetic laminations 18 adjacent to the poles of the electro-magnet and is mechanically connected to a cutter represented by the chain dotted rectangle 19. The cutter operates in conjunction with a shear plate (not shown).

The armature is pivotally mounted on a frame 20 by means of a pin 21 projecting from the frame 20. The electromagnet is mounted rigidly on the frame 20.

The springs 22 bear at their outer ends against lugs 23 integral with the frame 20. At their inner ends they bear against the armature.

A metal pressing or die casting or plastic moulding 24 is fixed (by means not shown for clarity) to the left hand lug 23 at one end. At the other end it is fixed by a clamping plate 25 to the electro-magnet. Ball or roller bearings 26 and 27 are located between tracks formed in the part 24 and in the case, which is indicated by shading. These tracks are all concentric with a line which is the axis of oscillation of all parts rigidly fixed to the frame 20.

The armature is also mechanically connected to the case by the metal tape 28 which with all operatively possible positions of the armature meets a cylindrical surface provided for it on the armature, tangentially. Both ends of the tape 28 are reinforced and made so that they can swivel at their attachment points allowing the tape to seat evenly on the cylindrical surface. The tape 28 is kept taut by the action of the spring 29 hearing at one end against the plate 25 and at the other end against the case. This spring 29 also forces the tracks in the part 24 against the ball or roller bearings 26 and 27 and the latter against the tracks in the case. The cantilever spring 30 normally holds one end of the tape 28 against the case, indicated by the shaded area, so that the tape connection between the armature and the case is sufiiciently rigid. Undue loads on the tape, however, such as due to impacts between the case and the floor, are relieved by flexing of the cantilever spring 30 away from the adjacent part of the case.

The spring 29 and the two springs 22 are arranged so that the static equilibrium position of the armature is at approximately the mean of its normal operative travel. Approximately the greatest amplitude of oscillation is normally obtained with the equilibriumposition arranged so that the corners of the armature and electro-magnet laminations are adjacent, as shown in the figure.

Examination of FIGURE 2 shows that for normal angles of movement of the armature the parts rigidly fixed to the frame 20 oscillate about the axis with which the tracks for the ball or roller bearings 26 and 27 are concentric. The armature, meanwhile, oscillates in the opposite sense about the pin 21 which is fixed to the frame 20. It is also clear that for normal angular movements of the armature the angular velocity ratio relative to the case between the electro-magnet and the armature is virtually equal to the ratio between the radius of the cylindrical surface on the armature under one end of the tape 28 and the distance between the centre of the pin 21 and the axis with which the tracks for the ball or roller bearings 26 and 27 are concentric.

What I claim is:

1. A vibrator motor comprising an electro-magnet assembly, an armature assembly, pivotal mountings for both said electro-magnet assembly and said armature assembly, mechanical coupling means from said electro-magnet assembly to said armature assembly to cause said electromagnet assembly and said armature assembly to move in anti-phase about their pivotal mountings the one with respect to the other under the constraint of said mechanical means when said electro-magnet is energised in such a way that the relative angular movements of said armature assembly and said electromagnet assembly are predetermined by said mechanical means.

2. A vibrator motor according to claim 1 further comprising a containing case, a frame mounted for small angle oscillatory movement in said case and to which frame said electro-magnet is rigidly secured and said armature is pivoted, and a further yielding pivot for said armature connected to said case, the pivoting of said armature to said frame providing the mechanical coupling from said electromagnet to said armature.

3. A vibrator motor according to claim 2, said yielding pivot comprises a bridge piece having two knife edge bearings, a V seating for one of'said bearings attached to said case, a V seating for the other of said bearings attached to said armature, and spring means urging said knife edge bearings into said V seatings.

4. A vibrator motor according to claim 2, comprising tracks on said frame and said case and bearings'operating on the tracks to permit the small angle oscillatory movement of said frame, and spring loads means bearing on said frame and said case.

5. A vibrator motor according to claim 4 said yielding pivot comprising a tape attached resiliently to said frame and attached to said armature and wrapped round an arcuate surface OIl said armature.

6. A vibrator motor according to claim 1 wherein in operation whereof the amplitude of the movements of said electro-magnet and said armature are inversely proportional to their respective polar moments of inertia.

7. An electric shaver including a vibrator mot-or ac cording to claim 3, a cutter, said case comprising a shear plate in operational juxtaposition with said cutter, said armature being in driving connection with said cutter.

8. An electric shaver including a vibrator motor according to claim 5, a cutter, said case comprising a shear plate in operational juxtaposition with said cutter, said armature being in driving connection with said cutter.

References Cited by the Examiner UNITED STATES PATENTS 2,565,697 8/ 1951 Odstrucil 3 l0-29 2,998,648 9/1961 Barron et al. 3 043.1 X 3,105,163 9/1963 Camp 31 029 3,155,855 11/1964 Fiitterer 31038 MILTON .O. HIRSHFIELD, Primary Examiner. D. F. DUGGAN, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2565697 *Feb 25, 1948Aug 28, 1951Borivoj OdstrcilElectric shaving apparatus
US2998648 *Dec 15, 1959Sep 5, 1961Barron Richard HElectric razor pivotally mounted in an outer casing
US3105163 *Mar 31, 1961Sep 24, 1963Schick IncElectric shaver reciprocating motor-drive unit
US3155855 *Feb 27, 1961Nov 3, 1964Braun AgTuned armature electromagnetic motor
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3906263 *May 23, 1974Sep 16, 1975Sperry Rand CorpVibrator motor in hand-held electric appliance
US4392092 *Dec 22, 1980Jul 5, 1983Braun AktiengesellschaftOscillating-armature motor for electric dryshavers and the like
US5632087 *Mar 28, 1995May 27, 1997Matsushita Electric Works, Ltd.Reciprocatory dry shaver
US7015602Mar 11, 2005Mar 21, 2006Braun GmbhSmall electric appliance with a drive mechanism for generating an oscillatory motion
US7288863 *Jan 9, 2006Oct 30, 2007Bruan GmbhElectric appliances having electric motors for driving oscillatory elements
US7504751Mar 11, 2005Mar 17, 2009Braun GmbhSmall electric appliance with a drive mechanism for generating an oscillatory motion
US7852182Aug 4, 2006Dec 14, 2010Koninklijke Philips Electronics N.V.Pendulum drive system for personal care appliances
US8276279 *Aug 9, 2010Oct 2, 2012Wahl Clipper CorporationHair clipper with a vibrator motor
US8549756Aug 23, 2012Oct 8, 2013Wahl Clipper CorporationHair clipper with a vibrator motor
US20050212365 *Mar 11, 2005Sep 29, 2005Bernhard KrausSmall electric appliance with a drive mechanism for generating an oscillatory motion
US20050212633 *Mar 11, 2005Sep 29, 2005Bernhard KrausSmall electric appliance with a drive mechanism for generating an oscillatory motion
US20060175909 *Jan 9, 2006Aug 10, 2006Bernhard KrausElectric appliances having electric motors for driving oscillatory elements
US20080204177 *Aug 4, 2006Aug 28, 2008Koninklijke Philips Electronics N.V.Pendulum Drive System for Personal Care Appliances
US20080286133 *May 18, 2007Nov 20, 2008Forcecon Technology Co., Ltd.Airflow generator
US20090121567 *Nov 13, 2007May 14, 2009Forcecon Technology Co., Ltd.Airflow generator
US20120030950 *Aug 9, 2010Feb 9, 2012Wahl Clipper CorporationVibrator motor
CN101237832BAug 4, 2006Apr 10, 2013皇家飞利浦电子股份有限公司Pendulum drive system for personal care appliances
WO2004028758A1 *Aug 19, 2003Apr 8, 2004Braun GmbhDrive device for the generation of an oscillating movement for a small electrical appliance
WO2007017823A1Aug 4, 2006Feb 15, 2007Koninklijke Philips Electronics, N.V.Pendulum drive system for personal care appliances
Classifications
U.S. Classification310/29, 30/43.92, 310/38
International ClassificationH02K33/04, H02K33/02, B26B19/28
Cooperative ClassificationH02K33/04, H02K33/02, B26B19/284
European ClassificationB26B19/28A, B26B19/28, H02K33/02, H02K33/04