Classifications

• • 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
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K15/00—Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
  • H02K15/04—Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of windings prior to their mounting into the machines
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K3/00—Details of windings
  • H02K3/46—Fastening of windings on the stator or rotor structure
  • H02K3/52—Fastening salient pole windings or connections thereto
• • 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
  • H02K37/14—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 with magnets rotating within the armatures

Definitions

• the present invention relates to a numerically controlled stepping motor intended in particular for driving the needles of measuring instruments and indicators, such as automobile on-board instruments.
• Such motors are intended to replace the motor components controlled by analog signals, such as logometers or actuators with crossed coils.
• Such stepping motors must have a negligible torque without current and a torque due to the current represented by a sinusoidal function.
• the object of the invention is to provide such an engine further having a low noise level, a low current consumption and a volume, and above all a reduced thickness.
• Each stator part wound, with the area of the second stator part closing the flow, constitutes a phase of the stator of the two-phase motor.
• the center lines of the two poles are spaced about 1.5 paces apart.
• the second stator part is made of a material of high magnetic permeability having four zones corresponding respectively to the four stator poles, said four zones being connected in pairs so as to ensure the closure of the magnetic flux of each of the stator parts.
• Such a stepping motor has a single plane of symmetry theoretically passing through the axis of rotation.
• the two air gaps corresponding to a phase are located on the same side of this plane of symmetry and the two air gaps corresponding to the other phase are arranged on the other side of said plane.
• This motor therefore has a certain sensitivity to a shift in the plane of symmetry relative to the axis of rotation of the rotor.
• patent US Pat. No. 5,245,233 concerning a motor having a stator comprising four half-coils arranged symmetrically with respect to the axis of the rotor and supported by iron cores parallel to the axis of the rotor.
• the cores are magnetically coupled and supported by this cylinder head.
• the stator of the motor according to this embodiment has four plane of symmetry theoretically passing through the axis of rotation.
• the cores of the coils have armatures added at their ends and forming poles cooperating with the magnet.
• the described method consists in delivering, for a step to be carried out by the armature, a sequence of pulses in which the ratio of the durations of pulse and exposure in one period (T), increases from one pulse to the next.
• the number of current pulses (m) or their durations, in the sequence is (are) determined according to the inertia of a system so that to a large inertia corresponds a small number of long pulses sent to the coils (L1, L2) of the stepping motor while conversely, to a low inertia corresponds a large number of finely stepped pulses at high frequency.
• the stepping motor described in this document comprises a stator having four electric coils and a rotor comprises a pair of magnetic poles.
• the aim of the present invention is to improve the performance of such two-phase motors by proposing a low-noise motor, accepting large manufacturing tolerances, and guaranteeing a torque in the absence of negligible current and a "torque-current" function of sinusoidal type.
• the invention relates more particularly to a two-phase stepping motor of the type comprising a stator part formed by a main cylinder head made of a soft magnetic material connected to four magnetic cores each supporting an electric coil, and a shaped rotor cylindrical with thin wall presenting 2N + 1 pairs of radially magnetized magnetic poles.
• the end of the magnetic cores is separated from the rotor only by a radial air gap, two diametrically opposed radial air gaps being supplied by coils flat in the same phase and exciting the corresponding cores in the opposite direction of magnetization.
• the magnetic flux is closed by an auxiliary yoke disposed on the side of the thin magnets opposite the magnetic cores.
• the number of pairs of magnetic poles is 2N + 1 with N equal to 1 or 2.
• the motor according to the invention does not have any part attached to the ends of the coil cores.
• the absence of such armatures makes it possible to eliminate a part, to facilitate assembly and to reduce the permeance of the magnetic circuit seen by each phase, therefore the section of the coil cores, while keeping very good field modulation due to current as a function of the angular position, which is favorable to the torque due to the current and to the reduction of the odd harmonics of this torque.
• the axes of the ends of the cores of the coils are in radial planes containing the axis of the rotor.
• the axes of the ends of the cores are oriented parallel to the axis of the rotor or perpendicular to the axis of the rotor.
• the cores are arranged radially.
• the auxiliary cylinder head is formed by a cylinder made of a soft magnetic material secured to the rotor.
• the auxiliary cylinder head is formed by a cylinder made of a fixed soft magnetic material placed inside the rotor and defining with the latter an internal radial air gap.
• the auxiliary cylinder head is magnetically connected to the main cylinder head.
• the rotor has on its inner and outer cylindrical surfaces 5 pairs of poles, ie 10 poles magnetized radially in alternating directions.
• the cores of the coils are parallel to the axis of rotation of the rotor.
• the main cylinder head is formed by a base extended by four cores each supporting a wafer type coil, the rotor being articulated around an axis of rotation parallel to the cores passing through the center of said square and being positioned to define the air gaps with the terminal parts of the cores protruding from the electrical coils.
• the main cylinder head is formed by a base extended by four perpendicular branches bent at 90 ° to form four cores of rectangular section each supporting a wafer type coil, the rotor being articulated around an axis of rotation parallel to the nuclei.
• the main cylinder head is formed by a base further extended by a central cylindrical part, with an outside diameter less than the inside diameter of the rotor, and forming the auxiliary cylinder head.
• the main cylinder head is formed by a base made of a soft material on which cores are magnetically coupled.
• two opposite coils are supported by a molded plastic part constituted by two bodies having an inner section complementary to the section of the core, said bodies being connected to one of their ends by a connection zone having a hole for the passage of the axis of the rotor, said connection zone being flexible enough to allow the folding of the bodies so that their central axes are aligned during winding electric wire.
• FIG. 1 shows a view of the motor in cross section
• - Figure 3 shows a top view of the cylinder head; - Figure 4 shows a view of the molded part supporting the coils.
• the stepping motor according to the example described with reference to the appended figures comprises a stator structure and a rotor.
• the stator structure is shown in section view in Figure 1 and in plan view in Figure 2. It comprises a main yoke (1) made of a soft magnetic material.
• This main cylinder head (1) has a base (2) in the form of a cross extended by four cores (3 to 6) extending perpendicular to the base (2) and parallel to the axis of rotation (7) of the rotor.
• Figure 3 shows a top view of the main cylinder head.
• the cores (3 to 6) are arranged at the four corners of the base (2) in the general shape of a cross having four branches (8 to 11) perpendicular and of equal length, extending radially with respect to a central part (12 ) disc-shaped.
• the central part is pierced by a hole (13) to receive an axis (7) of the rotor. This axis is embedded in the cylinder head.
• the cores are produced by deformation of the radial branches in order to straighten them by 90 ° relative to the plane of the base.
• the end (43 to 46) of the cores (3 to 6) facing the thin permanent magnet (29) is in the example described in the extension of the part of the core which supports an electric coil (14 to 17) in the shape of a cake. It is also possible to make a thinner motor, the cores being attached to a base by riveting or welding, the ends (43 to 46) of the cores being folded at 90 ° relative to the part of the core which supports an electric coil (14 to 17). Yet another variant consists in producing a main cylinder head comprising cores arranged radially in the plane perpendicular to the axis of the rotor.
• the rotor comprises a cylindrical magnet (29) equivalent to ten sectors (18 to 28) in the form of radially magnetized tiles, in alternating directions so as to present a SOUTH pole, alternately on the interior surface and on the exterior surface of the rotor.
• Each of the magnetized sectors occupies an angular sector of 36 °.
• the cylindrical magnet can be produced by association of independent magnetic parts, or by magnetization of the various zones of a ring preferably produced by molding, by compression or injection in an alloy with high coercive field of plastic neodymium-iron, for example the magnets sold under the name "NP8L" by the company DAIDO STEEL CORPORATION and made from powder sold by the company GENERAL MOTORS under the name of "MQI".
• the thickness of the magnet is one millimeter for a height of 2 millimeters and a diameter of the order of 10 millimeters.
• the air gap formed between the ends (43 to 46) of the main yoke and the outer surface of the thin permanent magnet (29) is about 0.4 to 0.5 millimeters.
• the magnet (29) is integral, in the example described, with an auxiliary yoke (30) of annular shape, supported by a molded plastic part (31) having a crown extended by a foot (32) of tubular shape.
• the crown has a peripheral groove in which the auxiliary cylinder head (30) is housed by overmolding.
• the tubular leg (32) forms the rotation shaft concentric with the axis (7) embedded in the main cylinder head.
• the coils (3 to 6) are mounted two by two on supports, an enlarged view of which is shown in FIG. 4.
• the supports consist of deformable molded plastic parts, having two tubular parts (34, 35) extended at each end by annular shoulders (36 to 39).
• the upper annular shoulders (37, 38) of the tubular parts respectively (34, 35) are joined by a connecting part (40) flat, pierced by a central hole for the passage of the axis (7) of the rotor.
• the motor has two supports of this type, arranged perpendicularly and slid around the cores (3 to 6).
• the connecting parts (40) of the two supports overlap and in the example described have a central allowance.
• the cores can be produced by deformation of the branches of a part made of a soft material, or by riveting independent cores on a base.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Iron Core Of Rotating Electric Machines (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9478703

Family Applications (1)

Country Status (3)

Family Cites Families (8)

• 1995
  • 1995-05-04 FR FR9505344A patent/FR2733859B1/fr not_active Expired - Lifetime
• 1996
  • 1996-05-03 WO PCT/FR1996/000670 patent/WO1996035255A1/fr not_active Ceased
  • 1996-05-03 EP EP96919858A patent/EP0824780A1/de not_active Withdrawn

Non-Patent Citations (1)

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