US3474270A - Vibrators - Google Patents

Description

Oct. 21, 1969 J. J. G. DIETSCH 3,474,270

' VIBRA'I'ORS Filed June 12, 1967 3 Sheets-Sheet 1 Oct. 21, 1969 I J. J. G. bjETscH v3,474,270

VIBRATORS Filed June 12, 1967 5 Sheets-Sheet 2 FIG.5

Oct. 21, 1969 J. J- G. DIETSCH VIBRATORS 3 Sheets-Sheet 5 Filed June 12, 1967 Bob E; II I2 Bob? United States Patent M 3,474,270 VIBRATORS Jacques Jean Gustave Dietsch, Paris, France, assignor to Societe anonyme des Etablissements Leon Hatot, Paris, Ifi'ance, a company of France Filed June 12, 1967, Ser. No. 645,247 Claims priority, application France, June 28, 1966,

Int. Cl. H021; 33/18, 35/06 US. Cl. 310-25 4 Claims ABSTRACT OF THE DISCLOSURE A flexion vibrator includes at least one cruciform assembly comprising four equal flexible branches radiating in a single plane perpendicular to an axis from a central fixed support along two mutually perpendicular diameters, and magnetic energising means including a pick-up coil and a motor coil respectively connected to the input and-output of an amplifier, for maintaining the branches in vibration by applying to the ends of each pair of branches lying on the same diameter oscillating forces of the same magnitude and direction, the forces exerted on half the pairs of branches being of opposite phase to those exerted on the remaining pairs of branches. Amotor may be formed by providing a rotor cooperating magnetically with the branches of such a vibrator so as to rotate in synchronism with their vibration.

This invention relates to vibrators, and is particularly, though not exclusively, concerned with electromechanical oscillators including a fiexion vibrator and means for converting the vibratory movement of the vibrator into unidirectional, preferably uniform, circular movement, or

vice versa. Such oscillators find application in the field 'of time measurement, particularly as driving apparatus for measuring time. They may also be used in a conventional manner as rhythmic signal generators.

A classic example of a vibrator of this type is the tuning fork, and, on the basis of this device, numerous alternatives have been proposed which in general aim at fulfilling the following two requirements:

An object of the present invention is to provide an improved form of vibrator which fulfills these requirements.

According to the present invention a fiexion vibrator includes at least one cruciform assembly comprising four equal flexible branches radiating in a single plane perpendicular to an axis from a central fixed support along two mutually perpendicular diameters, and magnetic energising means for maintaining the branches in vibration by applying to the ends of each pair of branches lying on the same diameter oscillating forces of the same magnitude and direction, the forces exerted on half the pairs of branches being of opposite phase to those exerted on the remaining pairs of branches. In such a structure the resultant of the reaction forces applied to the support is at all times zero.

The vibrator may comprise a single four-branch assembly or it may comprise a number of sets of four branches uniformly distributed about the axis; for example the vibrator may have eight branches separated by angles of 45 twelve branches separated by angles of 30 and so forth.

3,474,270 Patented Oct. 21, 1969 The branches may be made of metal, preferably a flexible alloy having a very low co-efiicient of expansion and elasticity such as Elinvar, so that the effect of fluctuations in temperature is virtually eliminated. Alternatively the branches may be formed of quartz. Each pair of branches may be formed integrally with one another by a blade which crosses at least one other blade at the centre. Alternatively the branches may be integral with the central support.

Conveniently the energising means include armatures of magnetic material carried by the ends of the blades, fixed coils co-operating with the armatures, and means for electrically energising the coils. The armatures may comprise permanent magnets, Each armature may cooperate with a motor coil energised to maintain the vibration of the branch, and with a pick-up coil responding to the movement of the branch to provide an induced signal to control the energisation of the motor coil, an amplifier having its input connected to the pick-up coil and its output connected to the motor coil. For example each motor coil may be supplied with direct current from a supply, such as a battery, through a transistor which is tripped by the current induced in the pick-up coil, for example as described in the applicants French patent specification No. 1,090,564.

In one form of the invention each armature is magnetised in a direction parallel to the associated branch, inwards towards the centre for one pair of branches and outwards away from the centre for another pair, and each fixed coil comprises a single coil cooperating with all the branches and co-axial with the assembly. Thus each armature may be of straight elongated form extending in a direction parallel to the associated branch, each coil being of square form. Alternatively each armature may be of arcuate form co-axial with the vibrator, each coil being of circular form.

In another form of the invention each armature is magnetised in a direction parallel to the axis, in one direction for one pair of branches and in the opposite direction for another pair, and each armature co-operates with one of a corresponding number of coils having their axes substantially parallel to the axis of the vibrator.

The invention may also be embodied in an electric timing motor including a vibrator as set forth, and a rotor mounted co-axially with it and having round its periphery a number of polar projections of magnetic material co-operating magnetically with the branches to cause the rotor to rotate in synchronism with their vibration. The rotor may comprise a wheel of ferromagnetic material having radial poles distributed uniformly around its periphery and separated by notches, while each armature carries a number of poles of substantially the same circumferential extent and spacing as the poles of the rotor. Preferably the number of poles of the rotor is a multiple of an odd number.

The poles of the stator and/or the poles of the rotor may be so asymmetrical so as to favour self-starting and unidirectional rotation.

The invention may be put into practice in various ways but certain specific embodiments will be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a perspective view of an elementary type of four-branch vibrator according to the invention;

FIGURE 2 is an axial section through an oscillator comprising a vibrator of the aforesaid type and means of maintaining vibrations;

FIGURE 3 is a diagrammatic plan view of the oscillator assembly of FIGURE 2;

FIGURE 4 is a view, similar to FIGURE 3, of an alternative form of oscillator;

FIGURES 5 and 6 are partial views of two modifications of the oscillator of FIGURE 2;

FIGURE 7 is a view similar to FIGURE 2, of a further form of oscillator;

FIGURES 8, 9 and are diagrammatic axial sectional views of a motor system comprising an oscillator according to the invention and a rotor driven without contact by the oscillator, FIGURE 8 showing the system at rest and FIGURES 9 and 10 showing the system in two extreme phases of operation;

FIGURE 80: is a diagrammatic view of the system of FIGURES 8 to 10, seen from below;

FIGURES 11 and 12 are diagrammatic views from underneath and in axial section respectively, of a complete motor system according to the invention, for driving the hands of a clock.

The vibrator shown in FIGURE 1 consists of two flexible blades L and L of equal length, disposed in the form of a cross so as to afford four branches radiating in a single plane, from a central support S, about a central axis aa, perpendicular to the common plane of the two blades L and L As a basis for description, it will hereinafter be assumed that the plane of the two blades is a horizontal plane, the axis aa being a vertical axis, but it must be appreciated that one of the advantages of the vibrator is that it can work satisfactorily in any attitude.

The blades L and L defining a coplanar four-branch assembly, may be separate from each other, being secured to the support S by any appropriate means, particularly by welding, riveting, or bolting. Alternatively the blades L and L may be cut from one and the same surface or the support S may be an integral part of one blade or of both.

The blades L and L are made from flexible resilient material, for example a metal such as steel, and preferably a metal having a low co-eflicient of expansion, and above all an elasticity modulus which remains constant over a wide range of temperatures, a particularly suitable metal being Elinvar.

In order to excite such a vibrator and maintain it in a state of vibration, oscillating forces F and F are applied to the ends of the blades L and L respectviely, parallel with the axis aa. The said forces always have the same value and at a given moment those on opposite ends of the same blade are in the same direction, but the opposite direction to those on the ends of the other blade. Thus the resultant of the forces of reaction withstood by the support by reason of the vibration of the blades L and L is constantly nil, which represents one of the great advantages of the vibrator according to the invention.

It must be noted that the same would apply to all vibrators which comprise a plurality of cruciform assemblies of the type shown in FIGURE 1 evenly distributed about a central axis and a central support. These vibrators, with eight, twelve, sixteen or more branches, of course, fall within the present invention.

FIGURES 2 and 3 show an oscillator comprising a vibrator of the type described in FIGURE 1 and electromagnetic means for maintaining its oscillations without physical contact.

At the ends of the blades L and L of the vibrator of this oscillator are disposed permanent magnet armatures A and A In the embodiment shown in FIGURES 2 and 3, these armatures take the form of small elongated straight parallelepipeds, consisting for example of ferrite, each situated at right-angles to the associated blade, and horizontally magnetised parallel to it, the directions of magnetisation of the armatures A being radially outwards, the directions of magnetisation of the masses A being radially inwards.

A coil Bob of square form is disposed horizontally beneath the blades L and L level with the armatures A and A so as to be opposite the vertical faces of the latter, from whtich they are separated by only a small peripheral gap. In a manner known per se, the Bob consists of two superimposed or juxtaposed windings, that is to say a pick-up winding and a motor winding connected respectively to the input and output of an amplifier. Thus the motor winding is fed from an electric battery P through a transistor TR which is itself controlled by electrical signals emitted by the pick-up winding, such an assembly being already known per se, particularly from French Patent No. 1,090,564 in the name of the applicants. In the assembly illustrated, a capacitor is connected be tween the base and the emitter of the transistor TR for separating the two windings.

The operation of such an oscillator is easy to understand: the direction of magnetisation of each of the armatures A and A is perpendicular to the adjacent portion of the turns of the coil Bob; these armatures being caused to vibrate in a direction which is itself perpendicular to the general direction of the turns in the diiferent zones of the coil facing the armatures A and A Under these circumstances, the vibrations of the armatures produce in the pick-up winding an induced current which trips the transistor which then allows a pulse of current to pass into the motor winding and apply a remote action to the armatures to ensure maintenance of the vibrations of the blades L and L This takes place at each vibration (oscillatory cycle) of the ends of the blades L and L As the armatures A are in the high position while the armatures A are in a low position and vice versa, and because moreover, the respective directions of magnetisation of the armatures A and A are directed oppositely in relation to the centre of the coil Bob, the interaction between the armatures and the conductors of the two coil windings, at the level of each blade end have a cumulative effect; the currents induced into the pick-up winding are added together and the same motor current passing through the motor winding produces at opposite forces on the armatures A A respectively, so that the vibrator assembly is maintained under the conditions of maintained vibration as previously defined.

In a view similar to that of FIGURE 3, FIGURE 4 shows an alternative embodiment of the oscillator according to the invention, in which the coil Bob, having two windings, is circular in form, and the armatures A and A have the form of circular segments bounded by cylindrical surfaces of revolution about the axis aa of the vibrator and of the coil, and by horizontal planes. The functioning of such an oscillator is as described above.

FIGURES 5 and 6 illustrate alternative embodiments in which the influence of the armatures A (that is to say A; or A on the coil Bob is reinforced by particular arrangements.

In the embodiment shown in FIGURE 5, at the end of each blade L (either L or L the magnetised armature A is secured by means of a yoke M of U-section soft iron, the armature A and the coil Bob being situated in the same horizontal plane between the limbs of the U; the yoke M constitutes a magnetic circuit channelling the field of the armature A in a closed circuit cutting the active conductors of the coil Bob (see the arrows).

FIGURE 6 shows another embodiment comprising the same elements, save that the permanent magnet armature A is divided into two portions mounted on the yoke M and framing the active conductors of the coil Bob.

In a view similar to that of FIGURE 2, FIGURE 7 shows an oscillator comprising a vibrator of the aforesaid type, in which the armatures, at the ends of the blades L and L are in the form of vertically magnetised bars which serve as insertable cores co-operating with cylindrical coils B012 and Bob (in FIGURE 7, only the two coils Bob co-operating with bars B of the blade L are shown). With such a system, it is possible to use coils Bob and Bob, each having one pick-up winding and one motor winding, the motor and pick-up windings respectively of the four coils being preferably connected in series, maintenance of the vibrator oscillations being for example and preferably achieved by a transistorised assembly similar to that described and illustrated in FIG- URE 2. l

FIGURES 8, 8a and 9 and illustrate diagrammatically a motor system comprising an oscillator according to the invention, in which the vibrator oscillations are converted into a movement of uniform rotation with out physical contact. FIGURE 8a being as has been stated a view of the motor system from underneath, FIGURES 8, 9 and 10 are axial sections along the sectional line xoy. Thus it should be emphasised that in each of these figures the right hand half and the left hand half represent sections in different planes. For example in FIGURE 9 the blade L on the left has moved down, and the opposite blade L will also have moved down, but the blade seen on the right is one will have moved up.

Carried by the ends of the blades L and L vibrating as described above, are magnetic poles P P respectively, such poles being for example afforded by flared out parts of yokes similar to the previously described yokes M. Mounted coaxially with the axis aa of the system is a rotor R. This rotor consists for example of a plane wheel made from ferromagnetic material and of small thickness, comprising poles p distributed at regular distances round its periphery and separated by notches e. Hereinafter, the angular distance separating two poles p measured at the axis, will be termed the polar step. Generally speaking, the number of poles p is equal to twice an odd number.

FIGURE 8 shows the motor system when the vibrator is at rest; FIGURES 9 and 10 showing the state of the system when the vibrator is vibrating, in two different directions. When, as shown in FIGURE 9, the poles p of the blade L move away from the poles p of the rotor R, the poles p of the blade L come closer to the rotor poles. The result is that the action of the poles p becomes predominant over that of the poles p so that a motor couple is transmitted to the wheel R. From an initial position in which it offered recesses e to the poles p (FIG- URE 8a), the wheel rotates through one half a polar step, coming into a position in which it presents to the poles p its immediately subsequent poles p instead of the notches e which were previously presented. During the following semi-vibration of the vibrator (FIGURE 10), the poles p move towards the wheel while the poles p move away from it. In the same way as previously, the result is that the wheel R again turns through half a polar step in the same direction. At each complete vibration of the vibrator, there is therefore a definite rotation throughout one polar step.

FIGURES 11 and 12 shown as assembly for driving the hands of a clock or the like fitted with a motor system according to the invention. This assembly comprises an oscillator of the type in accordance with FIGURES 4 and 5, a wheel R mounted integrally with a rotary spindle r coinciding with the axis aa of the oscillator, and of the type shown in FIGURE 8a. The poles p and p take the form of widened out parts of a yoke M made from soft iron, asociated with the yoke M similar to that shown in FIGURE 6. The poles p take the form of radial projections of the wheel R, separated by notches e, and, in the same way, the poles p and p have the same shapes 'and sizes as the poles p, as radial projections directed inwards towards the axis. The various elements of the assembly are housed in a casing B, within which fixed members such as s and s serve as supports for various fixed or movable elements; it can be seen that the support S of the vibrator is mounted in the centre of the piece s the spindle r passing without contact through a central bore in the support S.

The motor system of such an assembly functions in the manner described in relation to FIGURES 8, 9' and of the blades both of which 10, the spindle r of the motor system being finally. driven with a uniform movement of rotation, at the speed of one polar step per period of oscillation. of .the vibrator. As illustrated, movement of the spindle I, through the intermediary of gear trains such as E, E E causes movement of the various hands I 1;, 1 of the time indicating assembly. 1

The advantages of the vibrator according to the invention have already been stated above: elimination ofreactions on the support, and the possibility of operation in any position. The frequency of vibration of such a vibrator may be for example be between 10 and 1,000 c.p.s. Oscillators comprising such a vibrator, being fed from a source of direct current, with a very low rate of consumption, exhibit considerable autonomy of operation. Motor sys tems according to the invention, as. compared with conventional systems, show a considerable increase in the motor torque produced for equal consumption of electric power. Moreover, they offer the advantage of functioning without mechanical contact and therefore without wear and tear and without noise, althoughmotor systems other than those which have been described may be constructed by associating with an oscillator according to the invention, mechanical means adapted to convert the oscillations from the ends of the branchesof the vibrator of the oscillator into a uniform movement, particularly a movement of uniform rotation.

Moreover, means known per se may be employed in order to improve the operation of motor systems according to the invention. In particular, the frequency of the vibrator may be regulated by a system of masses which are disposed in more or less eccentric positions in relation to the vibrator, or by magnetic action. Means facilitating self-starting and unidirectional rotation of the rotor of the motor systems may be employed: for example, the poles p, p and p2, or the notches separating them, may be given an asymmetrical form; also, a mechanical element of the ratchet type may be employed in order to allow the rotor to rotate in one direction only.

Finally, the rotor R may comprise magnetised peripheral zones, particularly to constitute its poles p.

It goes without saying that the present invention is not confined to the embodiments described but extends to all the alternatives whichare in keeping with its spirit.

What I claim as my invention and desire to secure by Letters Patent is:

1. Electromechanical oscillator comprising, a flexion vibrator including at least one crusiform assembly comprising four angularly spaced, flexible branches of equal length in a single plane perpendicular to an axis from a central fixed support point extending outwardly from said point along two mutually perpendicular diameters; magnetic systems mounted at the free ends of said branches, symmetrically relative to said axis; at least one common pick up ooil parallel to said plane, coaxial with said axis and cooperating electromagnetically with said systems; at least one common motor coil, parallel to said plane, coaxial with said axis and cooperating electromagnetically with said systems for driving said branches in oscillations relative to said plane; an electric circuit to energize said motor coil in response to electric signals induced in said pick up coil trough said systems whereby the vibrator is sustained in vibration, the motor coil being disposed for applying to the ends of each pair of said branches on a same diameter oscillating forces of the same magnitude and direction, and the forces exerted on half the pairs of branches being of opposite phase to those exerted on the remaining pairs of branches.

2. An electromechanical oscillator as in claim 1 in which each of said systems comprise an armature magnetized in a direction parallel to an asociated branch applying magnetic force inwards towards the center for one pair of branches and outwards away from the center for another pair.

3. An electric motor comprising, a flexion vibrator including at least one cruciform assembly comprising four angularly spaced flexible branches of equal length in a single plane perpendicular to an axis passing through a central fixed point and along two mutually perpendicular diameters; magnetic systems mounted at the free ends of said branches, symmetrically relative to said axis; at least one common pick up coil parallel to said plane, coaxial with said axis and cooperating electromagnetically with said systems; at least one common motor coil, parallel to said plane, coaxial with said axis and cooperating electromagnetically with said systems for driving said branches in oscillations relative to said plane; an electric circuit to energize said motor coil in response to electric signals induced in said pick-up coil through said systems; a rotor mounted coaxially with said axis and said coils and having around its periphery a number of first magnetic polar projections; second magnetic polar projections associated with said branches, said first and second projections cooperating to cause the rotor to rotate in synchronis-m with the vibration of said branches.

4. An electric motor as in claim 3, in which said second polar projections are parts of said magnetic systems.

References Cited UNITED STATES PATENTS 3,150,337 9/1964 Allison 331-116 XR 1,781,513 11/1930 Holweck 84-409 1,763,853 6/1930 Karolus 84-409 XR 3,349,305 10/1967 Dietsch 331-116 XR 3,149,274 9/1964 Hetzel 318-128 2,690,646 10/1954 Clifford 58-116 2,986,686 5/1961 Clifford 318-254 3,212,252 10/1965 Nakai 58-23 2,606,222 8/ 1952 Clifford et 172-126 3,207,965 9/1965 Lavet 318-128 2,939,971 6/1960 Holt 318-128 XR MILTON o. HIRSHFIELD, Primary Examiner B. A. REYNOLDS, Assistant Examiner U.S. Cl. 'X.R. 58-23, 116; 74-15; 172-126; 310-29, 33; 331-116; 318-128

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