FR2725853A1 - STEPPER MOTOR HAVING A SIMPLIFIED ASSEMBLY STRUCTURE - Google Patents

Abstract

The stepper motor has two stators (20, 30) which respectively have coils (26, 36) for windings (27, 37). Terminal brackets (26f, 36f) are integrally molded with the coils by resin, and terminals (28a, 38a) are insert molded with their corresponding brackets. The binding ends (27a, 37a) of the windings are wound around exposed intermediate portions of the corresponding terminals, and connected to them. The ends of the terminals are soldered to a wiring plate (50). The motor part is electrically connected to and mounted on the wiring plate.

Description

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  The present invention relates to a step motor

  with steps having a simplified assembly structure.

  It generally relates to a stepping motor, for example of the permanent magnet type, of the variable reluctance type or of a hybrid type, and more particularly, a stepping motor having a simplified electrical wiring between the winding of the stator and

a wiring plate.

  It is known from the prior art, as disclosed in the application made available to the public of Japanese patent N 62- 44678, that the stator winding of a stepping motor of the permanent magnet type (AP ) is electrically connected to an external wiring plate by passing electrical wires through part of a wall

  circumferentially outside of the stator.

  When mounting the stepper motor on the wiring plate, not only the electrical connection between the stator winding and the wiring plate but also a fixing structure for mounting the stepping motor on the wiring plate are required. Consequently, the object of the present invention is to simplify the electrical connection and the mounting structure between a stepping motor and a

external wiring plate.

  Another object of the present invention is to provide a stepping motor which can simultaneously be electrically connected to a wiring board

  exterior and be attached to it.

  In a stepping motor according to the present invention, electrical terminals are fixed to one end of a stator by means of an insulating material and are extended outwards. The stator winding is electrically connected to a part of the terminals extended outwards and exposed. The terminals are attached to a wiring plate at an end portion thereof. So the electrical connection

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  between the stator winding and the wiring plate can be obtained at the same time as the stepper motor

  is fixed on the wiring plate.

  Preferably, the stator winding is supported in a resin coil and the terminals are formed in one piece with the coil by insert molding. The terminals extend radially and are bent in the shape of an L in the direction of the wiring plate to be soldered to it. L-shaped terminal simplifies mounting of stepper motor

on the wiring plate.

  The present invention will be well understood

  during the following description made in connection with

  the accompanying drawings, in which: Figure 1 is a sectional view of a stepper motor, taken along line I-I of Figure 3, according to a first embodiment of the present invention; Figure 2 is a cross-sectional view, on a large scale, of an upper stator of the stepping motor according to the first embodiment; Figure 3 is a plan view of the stepper motor according to the first embodiment; Figure 4 is a schematic view of a variant of an electrical terminal and a terminal support used in the first embodiment; Figure 5 is a schematic view of another variant of an electrical terminal and a terminal support that is used in the first embodiment; FIG. 6 is a schematic view of a new variant of an electrical terminal and of a terminal support that is used in the first embodiment; and FIG. 7 is a plan view of a stepping motor according to a second embodiment of the

present invention.

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  The present invention will be described in detail in connection with the first and second modes of

  realization shown in the accompanying drawings.

  The first embodiment shown in Figures 1 to 6 relates to an AP stepper motor of the type

  bipolar which can be used as a drive motor

  ment for a motor vehicle indicator.

  As shown in FIG. 1, the stepping motor mainly comprises a casing 10 made of non-magnetic metal and has the shape of an inverted U or of a cross-section, and a pair of lower and upper stators 20 and 30 mounted coaxially inside the housing 10. The housing 10 is closed by a lower plate 10a fixed to the lower end of a peripheral wall 11 and mounted on a wiring plate (for example a printed circuit board) 50 on which can be placed circuits of

  electronic controls for controlling the power supply

  electric stepper motor.

  A magnet rotor 40 is mounted in the stators 20 and 30 along their axis. The output shaft 41 of the rotor 40 is rotatably supported by the casing 10 and the lower plate 10a by means of a central support portion 12a of the upper wall 12 of the casing and of a bearing 13 mounted at the center of bottom plate 10a. The magnet rotor 40 is magnetized at its outer periphery to provide multiple

  magnetic poles in the circumferential direction.

  Thrust washers 42 and 43 support the rotor 40.

  As shown in Figures 1 and 2, the stator 20 comprises an annular yoke 20a having the shape of an L in cross section and an annular yoke 20b having the shape of a flat plate in cross section. The cylinder heads 20a and 20b are mounted along the same axis. The upper wall 21 of the cylinder head 20a is held parallel to the lower wall 22 of the cylinder head 20b and the lower end of the outer peripheral wall 23 of the

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  cylinder head 20b is in contact with the peripheral end

  exterior of the bottom wall 22.

  The cylinder head 20a comprises a multitude of magnetic polar teeth 24, each having the shape of a trapezoid and extending downward from the inner peripheral portion of the upper wall

  21 to give the shape of the L in cross section.

  The lower end 24a of each tooth 24 ends above the inner peripheral portion of the lower wall 22 of the cylinder head 20b. Teeth 24 are

  arranged circumferentially in a uniform pitch.

  The yoke 20a has a multitude of magnetic polar teeth 25, each extending from the inner peripheral portion of the lower wall 22 of the yoke 20b in a direction opposite to that of the teeth 24. The circumferential pitch between two adjacent teeth 25 is uniform, as is the pitch between the teeth 24. The teeth 25 are arranged along the inner peripheral wall 26a of a coil 26 as are the teeth 24 but are offset with respect to the teeth 24 along a half not in the circumferential direction. The upper end 25a of each upwardly extending tooth 25 terminates below the inner peripheral portion of the

  upper wall 21 of the cylinder head 20a.

  The coil 26 has the shape of a cross-sectional section and is made of an electrically insulating material such as a resin. The coil 26 generally has the shape of a ring and is arranged coaxially between the yokes 20a and 20b. The upper and lower walls 26b and 26c are arranged between the upper wall 21 of the cylinder head 20a and the wall

lower 22 of cylinder head 20b.

  As will be seen in FIG. 1, the coil 26 forms an air space in a ring between its inner peripheral wall 26a and the rotor 40. Two upper positioning projections 26d are formed in one piece by resin molding on the wall

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  inner device 26a of the coil 26 to be opposite one another. Only a projection 26d is shown in FIG. 2. The positioning projection 26d is disposed between two adjacent magnetic teeth 24 of the yoke 20a and is radially projecting towards the inside of the ring-shaped air space from from the upper portion of the inner peripheral wall 26a at a location just above the upper end 25a of the tooth 25 of the cylinder head 20b which is arranged between the two teeth

magnetic polar 24.

  In addition, the positioning projection 26d is in contact at its circumferential ends or in the form of an arc with the base portions of two magnetic teeth 24. Thus, the projection 26 defines the circumferential position of the yoke 20a relative to the coil. 26 in the air space in the form of a ring. The underside of the projection 26d may or may not be in contact with the upper end 25b of the tooth 25. The other positioning projection, which is not shown in FIG. 2, can be produced in the same way as

  that just described in Figure 2.

  On the inner peripheral wall 26a of

  the coil 26, two lower projections for positioning

  ment 26b which are opposite one another are formed in one piece by resin molding. Only a projection 26e is shown in FIG. 2. The projection 26e has the shape of an arc and is radially projecting inwards into the air space in the form of a ring from the lower portion of the wall. inner peripheral 26a lying just below the upper end 24a of the tooth 24 of the cylinder head a disposed between two adjacent teeth 25 of the

cylinder head 20b.

  In addition, the positioning projection 26e is in contact at its circumferential or arc-shaped ends with the base portions of two magnetic teeth 25. Thus, the projection 26e defines the

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  circumferential position of the cylinder head 20b relative to

  to the coil 26 in the ring-shaped air space.

  The upper face of the projection 26e may or may not be in

  contact with the lower end 24a of tooth 24.

  The other positioning projection 26e, which is not shown in FIG. 2, can be made in the same way

  as shown in figure 2 and described below

  above. Two tubular terminal supports 26f are formed in one piece with the coil 26 on the bottom wall 26c. As shown in Figures 1 and 2, the supports 26f extend radially outwards with an angular interval of 180 degrees between them, passing through cut portions lla in the peripheral wall 11 of the casing 10, the lower portion of the wall peripheral 22 of the cylinder head 20a and the upper portion of the peripheral wall of the cylinder head

stator 30.

  Terminals 28a of electrically conductive metal are fixed in the supports 26f by insert molding and extend radially outwards from the supports 26f. The terminals 28a are bent downwards to take the form of an L in the direction of the wiring plate 50. The lower ends of the terminals 28a are inserted into holes 51 made in the wiring plate 50 and welded with

  so as to be fixed by the weld 51a.

  On the coil 26, a stator winding or driving winding 27 is wound in the form of a solenoid, with its connecting ends extending radially outward and passing through the lower portion of the peripheral wall 23 of the cylinder head 20a and being wound on the terminals 28a for electrical connection with these. Thus, the electrical connection of terminal 28a with the wiring plate 50 and the mounting of the stator 20 on the plate 50

  can be done at the same time.

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  The stator 30 is generally constructed in the same way as the stator 20 and is assembled with the stator 20 coaxially inside the casing 10 by fixing the lower plate 10a to this casing. In addition, as shown in Figure 1, the stator 30 comprises yokes 30a and 30b in a ring, a coil

  36, a winding 37 and terminals 38a, which correspond

  lay respectively on cylinder heads 20a and 20b, on the

  coil 26, at winding 27 and at terminals 28a.

  The coil 36 also comprises a pair of terminal supports 36f, which correspond to the supports 26f of the coil 26, although only one support has been shown in FIG. 1. The supports 26f extend radially towards the exterior with an angular interval between them of 180 degrees, passing through the cut portion 11a in the peripheral wall 11 of the casing 10, the upper portion of the peripheral wall of the cylinder head 30a and the lower portion of the peripheral wall of the cylinder head 20a. As shown in Figure 3, the terminal supports 36f are moved relative to the following terminal supports 26f

  an angular interval of 90 degrees.

  Terminals 38a of electrically conductive metal are fixed in the supports 36f by insert molding and extend radially outwards from the supports 36f. The terminals 38a are bent downwards to take the form of an L in the direction of the wiring plate 50. The lower ends of the terminals 38a are inserted into holes 52 made in the wiring plate 50 and are welded so to be fixedly supported by the weld 52a. The connection ends 37a of the winding 37 extend outwardly passing through the upper portion of the peripheral wall of the yoke 30a and are wound on the terminals 38a for electrical connection with them. Thus, the electrical connection of the winding 37 with the wiring plate

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  and fixing the stator 30 on the plate 50 can

  be performed at the same time by welding 52a.

  The magnetic polar teeth of the stator 30, which correspond to the magnetic polar teeth 24 and 25 of the stator 20, are displaced relative to the teeth 24 and 25 respectively along the inner peripheral wall 26a of the coil 26 by a quarter

to not.

  As described above in connection with the first embodiment, the terminals 28a are molded by insert with the terminal supports 26f which are molded in one piece with the coil 26 of the stator 20, the connection ends 27a of the winding 27 are wound on the intermediate portion of the terminals 28a and electrically connected to them, and the lower ends of the terminals 28a are soldered to the wiring plate 50. In the same way, the terminals 38a are molded by insert with the supports of terminal 36f which are molded in one piece with the coil 36 of the stator 30, the connection ends 37a of the winding 37 are wound on the intermediate portion of the terminals 38a and electrically connected to them, and the lower ends of the terminals 38a are welded to the wiring plate 50. Thus, the stepping motor portion can be electrically connected to the wiring plate 50 and fixed

on this one.

  The electrical insulations of the terminals 28a vis-à-vis the peripheral walls of the casing 10 and the stator 20 and the electrical insulations of the terminals 38a vis-à-vis the peripheral walls of the casing 10 and the stator 30 are provided by the terminal supports 26f and 36f, respectively. Therefore, no additional material or insulation is required to

  ensure the electrical insulation of the terminals.

  The supports 26f with the terminals 28a are angularly offset by 180 degrees with respect to each other and the supports 36f with the terminals 38a are with 180 degrees with respect to each other. In addition,

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  terminal supports 26f and terminals 28a are angularly offset from terminal supports 36f and terminals

38a of 90 degrees.

  Consequently, the fixing positions of the terminals 26f and 36f on the wiring plate 50 are ensured with intervals between them, and as a result, the stepping motor portion can be

  stably supported at a multitude of locations

  elements on the wiring plate 50. The terminals 26f and 36f being arched in the form of L and extending towards the outside of the wiring plate 50, the connection of the terminals 26f and 36f with the wiring plate 50 can be

easily performed.

  Furthermore, as described above, the upper and lower positioning projections 26d and 26e are formed so as to project radially inwards from the inner peripheral wall 20a into the shaped air space. ring, and in the same way, the upper and lower positioning projections are formed so as to project from the stator coil 30 into the air space in the form of a ring. Thus, the air space necessarily formed in dead space between the inner peripheral walls of the stators 20 and 30 and the outer peripheral wall of the rotor 40 is effectively used by extending the projections of

positioning towards its interior.

  In accordance with this arrangement, the position-

  The cylinder heads in the circumferential direction relative to the coils can be made with precision so that no circumferential movement is caused between them. As the positioning is reached inside the dead space, the axial length of the coil 26 can be shortened. As a result, the stepper motor can be built under

  a flatter shape, with reduced dimensions.

  In addition, the terminal supports 26f and the positioning projections 26d and 26e are formed in a

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  piece with the coil 26 by resin and the terminal supports 36f and the positioning projections 36d and 36e are formed in one piece with the coil 36 with resin. Terminals 28e and 38e are insert molded with terminal supports 26f and 36f, respectively.

  Therefore, one can easily perform not alone-

  ment the formation of the terminal supports 26f and 36f, the positioning projections 26d and 26e and the positioning projections 36d and 36e on the respective coils 26 and 36, but also the fixing of the terminals 28a and 38a

  in the respective supports 26f and 36f.

  In the assembly of the stepping motor, the coil 26 is maintained or placed between the yokes 20a and 20b coaxially so as to form the stator 20 and the coil 36 is maintained or placed between the yokes a and 30b coaxially in order to form the stator 30. The stator 20 is inserted coaxially in the casing 10, while there is insertion of the terminal supports 26f in the cut portions lla of the casing 10. Then, the stator 30 is inserted coaxially in the casing 10 so as to be fixed to the stator 20, while inserting the terminal supports 36f in the cut portions lla of the housing 10. The lower plate 10a is fixed to the open end of the housing 10 to complete the assembly of the stepping motor portion. The stepping motor portion is mounted on the wiring plate 50 by inserting the lower ends of the terminals 28a and 38a in the corresponding holes 51 and 52 and by welding

  terminals 28a and 38a with the corresponding conductive patterns-

  which are formed on the wiring plate 50.

  Thanks to the integral resin molding of the terminal supports with the coils 26 and 36 and the insert molding of the terminals with their supports, the assembly of the stepping motor is simplified. The fixing of the stepping motor portion on the wiring plate 50 and the electrical connection of the windings 27 and 38 with the wiring plate 50 are carried out simultaneously.

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  It will be noted that the shape of the terminals can be modified to have that of a plate, a rectangular rod or a circular rod, as shown in FIGS. 4, 5 and 6, respectively. In these variants, the terminals 28b, 28c and 28d are inserted in one end, and fixed to this end, of the respective supports 26g, 26h and 26i which correspond to the

supports 26f.

  In addition, the terminal supports can be extended at irregular angular intervals. In addition, the winding 27 does not need to be mounted around the coil 26 in the form of a solenoid but can be wound beforehand in the form of a

  solenoid, and then be inserted into coil 26.

  The terminals 28a and 38a need not be molded by insert with the terminal supports 26f and 36f, but can be fixed to the coils 26 and 36 in the absence of any support. Alternatively, the terminals can be fitted snugly in their supports. In addition, the terminal supports can be extended downward from the bottom wall of the stator, the terminals extending only in the downward or axial direction so that their radially outward projection is avoided in order to reduce the radial length of the

step-by-step engine.

  The coils do not need to be supplied separately from the windings, and this can be avoided by

  molding the windings and supporting the windings-

  molded inside the stators 20 and 30. In this case, the terminal supports can be inserted into through holes made in the outer peripheral wall of the casing 10 using insulating materials. According to this variant, the casing 10 can be formed by resin molding and integral formation with

  the terminal supports for inserting the terminals.

  Thus, the structure for maintaining the terminals on the

casing 10 is simplified.

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  The present invention can be applied not only to a bipolar drive type AP stepper motor, but also to a drive type unipolar AP stepper motor, which is shown in Fig. 7 as a second embodiment. This unipolar stepping motor, like the motor of the embodiment described above, comprises a pair of upper and lower stators. The upper stator coil has three tubular terminal supports 61 to 63 which project radially outward at an angular interval of 45 degrees. The coil of the lower stator also comprises three tubular terminal supports 71 to 73 which project radially outwards at an angular interval of

  45 degrees, at a portion opposite to supports 61 to 63.

  Electrically conductive terminals 61 to 63a and 71a to 73a are molded by insert at one of their ends with the terminal supports 61 to 63 and 71 to 73, respectively. Terminals 61a to 63a and 71a to 73a are arched down to take the shape of an L in order to be soldered to the wiring plate at their other ends, like terminals 28a in the embodiment described above. . The connection ends 81 to 83 of the upper stator windings and the connection ends 91 to 93 of the stator windings

  are wound around the intermediate portions

  corresponding exhibits, and connected to them,

  terminals 61a to 63a and 71a to 73a, respectively.

  According to this unipolar stepping motor, the electrical connection of the windings to the wiring plate and the mounting of the motor portion on this plate can be carried out at the same time and in a simplified manner. The angular interval to separate terminals 61 to 63 from each other and terminals 71 to 73 from each other can be made formless and equal

at 120 degrees.

  The present invention which has just been described should not be limited to stepping motors of the type

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  AP but can be applied to other types of stepping motors such as stepping motors of the variable reluctance type or stepping motors of the hybrid type. Furthermore, the number of stators of stepping motors is not limited to two, but can be increased to three or reduced to one. Stepper motors can be used as driving sources not only for a vehicle indicator but also for other devices.

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Claims (10)

  1 - Stepping motor characterized in that it comprises: - a wiring plate (50); - a stator (20, 30) having a drive winding (27); a rotor (40) having a shaft (41) and rotated by a magnetic force;   - electrical terminals (28a-28d, 38a, 61a-   63a, 71a-73a) extending from the stator to   the exterior in different angular directions   rents from each other, each terminal being connected to the drive winding, inserted in the wiring plate at one of its ends in the axial direction of the rotor shaft and fixed to the wiring plate; and - electrical insulators (26f-26i, 36f, 61-63, 71-73) now fixedly on the stator   the other end of each of the terminals.   2 - Stepper motor characterized in that it comprises: - a wiring plate (50); - a ring-shaped stator (20, 30) comprising a ring-shaped coil (26, 36) and a driving winding (27, 37) supported in the coil; - a rotor (40) comprising a shaft (41) and rotated by a magnetic force; and   - electrical terminals (28a-28d, 38a, 61a-   63a, 71a-73a) fixed to the coil at one of their ends so as to extend outwards in different angular directions from each other, each terminal being connected to the driving winding, inserted in the wiring plate at one of its ends in the axial direction of the shaft of the   rotor and fixed to the wiring plate.   3 - Stepping motor according to claim 2, characterized in that: 2725853   - the terminals (28a-28d, 38a) are offset angularly 90 degrees.   4 - Stepping motor according to claim 2, characterized in that: the terminals (61a-63a, 71a-73a) are   angularly shifted irregularly.   - Stepper motor according to any one   claims 2 to 4, characterized in that:   - The stator (20, 30) has a peripheral wall (23); and   - terminals (28a-28d, 38a, 61a-63a, 71a-   73a) extend in the form of an L towards the plate   wiring (50) through the peripheral wall.   6 - Stepping motor according to any one   claims 2 to 4, characterized in that:   - The stator (20, 30) has a bottom wall, parallel to the wiring plate (50); and - the terminals extend axially towards the   wiring plate crossing the bottom wall.   7 - Stepping motor according to any one   claims 1 to 6, characterized in that:   - the terminals are soldered to the plate   wiring at one of their ends.   8 - Stepping motor according to any one   claims 1 to 7, characterized in that:   - the stepping motor is of the bipolar drive type. 9 - Stepping motor according to any one   claims 1 to 7, characterized in that:   - the stepping motor is of the unipolar drive type. - Stepper motor according to any one   claims 1 to 9, characterized in that:   - the terminals are made in the form of a plate, a rectangular rod or a circular rod.   11 - Multi-phase stepper motor, charac- terrified in that it includes: 16 2725853   - a wiring plate (50); - a multitude of ring-shaped stators (20, 30) stacked on top of each other, each stator comprising a ring-shaped coil (26, 36) and a driving winding (27, 37) supported in the coil;   - a multitude of electrical terminals (28a-   28d, 38a, 61a-63a, 71a-73a) fixed to the coil at one of their ends to extend outwards in different angular directions from each other, each terminal being connected to the winding d attack, inserted in the wiring plate at one of   their ends and attached to the wiring plate.   12 - Multi-phase stepping motor according to claim 11, characterized in that: - the stators are stacked in pairs; and - the terminals in each of the stators are offset regularly by 180 degrees from each other. 13 - Multi-phase stepping motor according to claim 11, characterized in that: - the stators are stacked in pairs; and - the terminals in each of the stators are   angularly offset by 90 degrees from each other.   14 - Stepper motor characterized in that it comprises: - a wiring plate (50); - a ring-shaped stator (20, 30) having a ring-shaped coil (26, 36) and a drive winding (27, 37) supported in the coil;   - a multitude of terminal supports (26f-   26i, 36f, 61-63, 71-73) formed in one piece with the coil and extending from the stator outwards in different angular directions; and   - a multitude of electrical terminals (28a-   28d, 38a, 61a-63a, 71a-73a) molded by insert with the terminal supports, respectively, to extend therefrom, each terminal being connected to 17 2725853   the attack winding, inserted in the plate   wiring and attached to this plate at one end.   - Stepping motor according to claim 14, characterized in that: - the terminal supports extend only in the radially external direction from the coil; - the electrical terminals are formed in L and include unmolded portions which extend outside the terminal supports; and - the winding is electrically connected to unmolded portions.