Classifications

• • G—PHYSICS
  • G04—HOROLOGY
  • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
  • G04C13/00—Driving mechanisms for clocks by master-clocks
  • G04C13/08—Slave-clocks actuated intermittently
  • G04C13/10—Slave-clocks actuated intermittently by electromechanical step advancing mechanisms
  • G04C13/11—Slave-clocks actuated intermittently by electromechanical step advancing mechanisms with rotating armature
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
  • H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
  • H02K21/24—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets axially facing the armatures, e.g. hub-type cycle dynamos
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K37/00—Motors with rotor rotating step by step and without interrupter or commutator driven by the rotor, e.g. stepping motors
  • H02K37/10—Motors with rotor rotating step by step and without interrupter or commutator driven by the rotor, e.g. stepping motors of permanent magnet type
  • H02K37/12—Motors with rotor rotating step by step and without interrupter or commutator driven by the rotor, e.g. stepping motors of permanent magnet type with stationary armatures and rotating magnets
  • H02K37/125—Magnet axially facing armature

Definitions

• Stepper motor especially for electronic watch.
• the present invention relates to a stepping motor, in particular for an electronic watch, comprising a permanent magnet rotor having several pairs of poles with magnetization axes parallel to the axis of rotation and distributed around the latter, a stator provided an upper pole piece and a lower pole piece, each of these pieces being magnetically connected to one end of a core carrying a coil periodically traversed by current pulses, and each of them having polar sectors which extend radially opposite an axial face of the rotor.
• stepper motors whose stator is formed by two pairs of pole pieces which extend one above the rotor and the others below.
• the pole pieces located face to face on the same side of the rotor are separated by a diametrical air gap and the two air gaps are oriented differently.
• the pulses which excite the coil are of alternating polarity and the rotor advances at an angle equal to that which separates two axes of magnetization during each pulse.
• the object of the present invention is to produce an engine of this kind comprising the targeted improvement.
• the stepping motor according to the invention is characterized in that the pulses are of alternating polarity, the number of sectors of each pole piece is equal to half the number magnetization axes of the rotor, and the pole plates are shaped so that the positions corresponding to the balance of forces between the rotor and the pole pieces, in the case where the coil is energized and in that where it is not excited, are rotated relative to each other.
• FIG. 1 is a top plan view of the pole pieces and of the rotor
• FIG. 2 a view in longitudinal section passing through the axis of the rotor
• FIG. 3 a partial plan view, on a light scale greatly enlarged, showing the opening of the pole pieces in an alternative embodiment
• FIGS. 4, 5 and 6 are partial plan views similar to that of FIG. 3 showing other execution variants
• FIG. 7 is a sectional view along line VII-VII of the, fig. 6, on a still enlarged scale, illustrating a detail of this figure
• FIG. 8 is a view similar to FIG. 3 showing another embodiment of the engine
• FIG. 9 also a plan view similar to FIG. 3, showing a final embodiment.
• the general arrangement of the motor is shown in Figs. 1 and 2.
• the motor frame comprises an upper element 1, for example a brass bridge and a lower element 2 which may be constituted by a second bridge or by a frame element of the movement in which the motor is incorporated.
• the frame elements 1 and 2 each comprise a bearing 3 which supports one of the ends of the shaft of a rotor 4.
• This rotor comprises for example a shaft 5, the upper part of which forms a pinion and the lower part passes through two washers 6 and the disc 7 constituting the cylindrical magnet of the rotor.
• the shaft 5 has the usual pivots which are engaged in the bearings 3.
• the frame elements 1 and 2 are connected to each other by two pillars 8, one of which is visible in FIG. 2. These pillars are also used to position a lower stator part 9 and an upper stator part 10, as well as a spacer 11 made of a non-magnetic material, for example brass.
• the spacer 11 and the pole pieces 9 and 10 are also fixed and centered by two pins 12, one of which is visible in FIG. 2 and by corresponding screws 13.
• the pillars 9 also serve to fix the upper deck 1 by means of screws 14 and spacing sockets 15.
• the two stator parts 9 and 10 are elongated flat plates made of a ferromagnetic material with high permeability and low remanence, one of which extends above the upper face of the magnet 7 and 1. other below its underside.
• the bent ends of these pole pieces located opposite the rotor, are shaped so that they can be connected to the ends of a magnetic core (not shown) which supports the excitation coil of the motor. It is an elongated coil, the same kind as that used in many types of stepper motors.
• This coil will be connected to the circuit of the timepiece so as to be periodically excited by pulses of current of alternating polarity, so that the pole pieces 9 and 10 each constitute alternately a north pole and a south pole during the passage of the pulses whereas between the pulses, they constitute masses of ferromagnetic material playing the role of an armature with respect to the permanent magnet of the rotor.
• Each pole piece has, opposite a circular axial face of the magnet 7, a profiled opening of generally circular shape, the opening of the pole piece 10 being designated by 16 in the drawing.
• This opening delimits three interior sectors 17, of the same dimensions which are distributed at 120o from each other and which each cover approximately an angle of 60o, so that they provide between them three empty zones also of 60o of angular opening.
• the rotor assumes a position of equilibrium due to the forces of attraction between its different polar zones and the parts of the pole pieces 10 or 9 which are in the vicinity. Thanks to the cutting or to the particular conformation of the sectors 17, this equilibrium position is different from that which is obtained if the pole pieces 9 and 10 are magnetized by the wise step of a direct current in the coil.
• the rotor undergoes a torque which puts it in rotation and by its inertia, it moves to the next neutral equilibrium position.
• FIGS. 3 to 9 give examples.
• the opening 18 of the pole piece 10 has a circular shape coaxial with the magnet 7 and extends over a diameter very slightly greater than that of the magnet 7.
• This profiled opening has three sectors 19 which are arranged like sectors 17 but one of the edges 20 of which, instead of being radial, is cut obliquely at an angle ⁇ of a few degrees relative to the radial direction.
• fig. 4 shows a variant in which the pole piece 10 is seen with an opening 21 also centered on the axis of the rotor 7.
• This opening 21 has parts in the form of narrow slots which delimit three sectors 22 which are asymmetrical with respect to a radius passing through their center of gravity. As seen in the drawing, these sectors each extend over more than 60o.
• the rotor 7 is shown with apparent N and S poles in the face facing the pole piece 10 and the pole areas are delimited by dotted lines.
• the position which the rotor takes in the absence of current and which it occupies between the steps of the motor becomes a position of imbalance at the time of the pulse in the coil when the pole pieces 9 and 10 are transformed into poles , magnetic respectively N and S or S and N depending on the polarity of the pulse.
• the rotor 7 then turns one step in the direction of the strongest attraction caused by this asymmetry.
• the S poles of the rotor came in place of the N poles and vice versa.
• the opening 26 presented by the plate 10 in this variant comprises' sectors 27, one of the edges 28 of which is folded in the direction of the rotor.
• the homologous edges of the sectors of the pole piece 9 are also folded in the direction of the cylindrical magnet 7.
• FIG. 8 shows embodiments which include new improvements compared to the embodiments envisaged until now.
• the general arrangement of the engine has the same structure and it can be seen in particular in FIG. 8 the periphery of the rotor 7 which is arranged between an upper pole piece 10 and a lower pole piece 9.
• Polar zones N and S designated by 31 are formed on the rotor 7 .. These polar zones determine six axes of magnetization parallel to the 'axis of the rotor, distributed 60 from each other and oriented alternately, the North and South poles succeeding each other on the upper face of the rotor, while poles of opposite names follow one another in the same way on its underside.
• the pole pieces are pla ques planes and their extreme edges extend in an arc coaxially with the rotor 7 a little beyond the periphery of the latter.
• the pole piece 10 has a profiled opening which firstly comprises a circular central part 30 ⁇ oaxial to the rotor and whose diameter is slightly less than the internal diameter of the pole areas 31.
• the profiled opening of the stator piece 10 has at in addition to three notches with parallel edges 32 which are distributed at 120o from one another and which extend obliquely outwards. Each of these notches 32 has an end with a curved edge which extends beyond the periphery of the rotor.
• the three notches 32 are of the same dimensions and all three open into the opening 30 in regions which are located 120o from one another. Their width is such that the polar sectors 33, of slightly asymmetrical shape, delimited by the notches 32 and by the central zone 30, extend over arcs which are slightly less than the arcs covered by two adjacent polar zones 31.
• the pole piece 9 has a profiled opening (30 '. 32') which has exactly the same shape and the same dimensions as the opening (30, 32) of the piece 10. It therefore also has a central zone 30 'circular and three notches with parallel sides 32'. As seen in fig. 8, the orientation of the notches 32 'is slightly different from that of the notches 32. Thus, the central opening . of the part 9 can be considered to be offset by a certain angle around the axis of the rotor with respect to the opening 30, 32. This offset is 30 in the embodiment described here.
• each step of the motor can correspond to a rotation of an angle of 30o.
• steps of 60o in which case, at the end of each step, the polar zones S of the rotor come to occupy the location q occupied the N polar zones at the start of the step.
• the opening 30, 32 should include a circular central zone similar to zone 30 and two diametrically opposite notches similar to the notches 32, 32 '.
• Fig. 9 represents yet another form of execution.
• the pole piece 10 again has a profiled opening 30, 32 which has exactly the same shape and the same arrangement as in FIG. 8.
• the rotor 7 has six pairs of poles for its part and we see in FIG. 9 the polar zones 31 alternately N and S of the upper face of this rotor.
• the profiled opening here has a central zone 30 'and two oblique notches 32' which are diametrically opposite but which, moreover, have the same shape and the same dimensions as the three notches 32 provided in the pole piece 10.
• the rotor spontaneously places itself in a stable equilibrium position in which two polar zones 31 are arranged symmetrically with respect to a polar sector limited by two adjacent notches 32 and 32 '.
• one of the notches 32 'of the lower stator part 9 plays the role of. brake and stops the rotor in this locking position.
• the rest position shown in fig. 9 it can be seen that two pole areas of the underside of the rotor which are respectively opposite the pole areas S3 and N3 are partially opposite the notches 32 '. This circumstance causes a strengthening of the stable and static balance already existing by the effect of the three notches 32 of the pole piece 10.
• the current pulses in the coil are of alternating polarity.
• the polar zones opposite to the zones N1, S1 and N3 are zones SN and respectively S which are located opposite a polar zone S and like the polar zone S which is opposite to N3 is partially discovered by one of the notches 32 ', the effect of the crown sector which extends between the two notches 32' on the rotor is a torque which also acts counterclockwise.
• the rotor is rotated. It takes a step of 60o until reaching a new position of stable equilibrium. This rotational movement comprises a first unlocking part followed by a fall into the new stable position.
• FIG. 9 the functional conditions of FIG. 9 can also be produced if the pole piece 9 has a profiled opening which has a central zone 30 ′ and a single notch 32 ′.
• the pole piece 9 has a profiled opening which has a central zone 30 ′ and a single notch 32 ′.
• the arrangement and shape of the openings of the pole pieces are possible for the arrangement and shape of the openings of the pole pieces. So, for example, instead of the circular magnet having a slightly smaller diameter than that of the openings 16, 18, 21, 24, 26 and 30, 32, it could also have a slightly larger diameter and the relative dimensions of the polar sectors and notches could be different from what is shown in the drawing.
• the rotor rotates 60o, which corresponds to the angular spacing between two axes of magnetization.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Electromechanical Clocks (AREA)

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Family Cites Families (11)

• 1981
  • 1981-04-08 EP EP19810900817 patent/EP0059183A1/de not_active Withdrawn
  • 1981-04-08 WO PCT/CH1981/000039 patent/WO1982000929A1/en unknown

Non-Patent Citations (1)

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