Vibration motor, in particular for timepiece movement

Abstract

The invention relates to a vibration motor (1), in particular for a timepiece movement, comprising a rotor (2) equipped with a magnet (32), and a stator (3) equipped with at least one coil (31) capable of actuating the rotor (2) in rotation, the rotor (2) being rotated by the at least one coil (31) when the rotor (2) is actuated by the at least one coil (31). The rotor (2) rotates relative to the stator (3) and oscillates between two limit positions, characterized in that the vibration motor comprises an elastic reset device for resetting the rotor between the two limit positions and an intermediate rest position when the rotor (2) is no longer actuated by the coil (31); the vibration motor (1) generates each step by means of a rotational oscillating movement of the rotor (2).

Description

Technical Field

[0001] This invention relates to the field of stepper motors, particularly for use in the watchmaking industry. More specifically, this invention relates to a vibration motor or oscillating motor. Background Technology

[0002] In most electronic watch movements, the energy required to rotate the hands (such as the second, minute, and hour hands) is provided by a stepper motor (such as a Lavet motor).

[0003] These single-phase motors rotate their rotors in a stepping manner, with each step representing a half-turn relative to the stator, defining one second. Each step of the rotor drives the gear train in the watch movement, which in turn drives the hands. The stepping rate is typically determined by a time base with a quartz resonator.

[0004] When the motor is running, the positioning torque holds the rotor in a set position, and the magnet-coil torque allows the rotor to rotate between these positions. However, since this torque is a sinusoidal function of the rotor position, efficiency losses are observed during partial rotation.

[0005] The rotor is also mounted in bearings to enable its rotation. However, this assembly generates friction between the rotor pivot and the bearings. This friction is caused by the weight of the rotor, the lateral attraction of the rotor magnets, and the contact between the gear train and the rotor pinion when the rotor drives the gear train.

[0006] As a result, these problems lead to energy loss, resulting in increased energy consumption compared to the energy required for efficient motor operation. Summary of the Invention

[0007] The present invention aims to overcome all or some of the above-mentioned disadvantages by providing a motor that consumes less fuel compared to a Lavet motor.

[0008] Therefore, the present invention relates to a vibratory motor, particularly for use in watch movements, comprising a rotor equipped with a magnet and a stator equipped with at least one coil capable of actuating the rotor to rotate in a stepwise manner; when the rotor is actuated by the coil, the rotor rotates relative to the stator and oscillates between two angular extreme positions.

[0009] A significant feature of the present invention is that the motor includes an elastic reset device for resetting the rotor between an extreme position and an intermediate rest position when the rotor is no longer actuated by the coil; the motor generates each step by means of the rotational oscillating motion of the rotor.

[0010] The working principle of an electric motor is that each step is generated by the rotor rotating and oscillating between two extreme positions at its resonant frequency. In this way, the motor reciprocates, thereby achieving incremental forward movement.

[0011] Compared to a single-phase Lavet motor, this motor can reduce the rotor's angular travel, making the electromagnetic torque between the magnet and the coil more efficient because it is located near the maximum value of the torque sine function.

[0012] Furthermore, the rotor is guided to rotate by the aforementioned elastic reset device instead of bearings, thereby avoiding friction between the rotor spindle and the bearings that hold the rotor spindle.

[0013] This invention can reduce energy loss, thereby reducing motor consumption; for example, for some motors, it can reduce consumption by half.

[0014] According to a particular embodiment of the invention, the resilient reset device includes a flexible guide mechanism arranged to suspend the rotor on the stator.

[0015] According to a particular embodiment of the present invention, the flexible guide mechanism includes an upper flexible portion connected to the top of the rotor above the stator, and a lower flexible portion connected to the bottom of the rotor below the stator.

[0016] According to a specific embodiment of the present invention, the upper flexible portion and / or lower flexible portion of the flexible guide mechanism includes at least one pair of non-crossing flexible blades, preferably two pairs of parallel non-crossing flexible blades.

[0017] According to a specific embodiment of the present invention, the upper flexible portion and / or lower flexible portion of the flexible guide mechanism includes at least one single flexible blade, preferably two single flexible blades arranged in parallel.

[0018] According to a specific embodiment of the present invention, the flexible guide mechanism includes a static element attached to the stator and a dynamic element attached to the rotor, the static element and the dynamic element being connected by flexible blades on the flexible guide mechanism.

[0019] According to a particular embodiment of the invention, the flexible guide mechanism includes an intermediate annular portion arranged around a rotating spindle on a rotor, wherein a first pair of flexible blades connects the intermediate annular portion to a dynamic element, and a second pair of flexible blades connects the intermediate annular portion to a static element.

[0020] According to a specific embodiment of the present invention, two pairs of flexible blades are symmetrically arranged on both sides of the central annular portion.

[0021] According to a particular embodiment of the invention, the flexible guide device includes a central annular portion arranged around a rotating spindle on a rotor, wherein a first single flexible blade connects the central annular portion to a dynamic element, and a second single flexible blade connects the central annular portion to a static element.

[0022] According to a particular embodiment of the invention, the motor includes a pinion for engaging with a gear train, particularly a gear train in a watch movement, the pinion being pivotally mounted above the rotor.

[0023] According to a particular embodiment of the present invention, the motor includes a ratchet with a check pawl, a movable pawl mounted on the rotor, and a fixed pawl mounted on the stator.

[0024] According to a particular embodiment of the invention, in a first rotational direction of the rotor, a meshing pinion and a ratchet are attached to the rotor, while in a second rotational direction of the rotor, the meshing pinion and the ratchet are assembled to be freely pivotable about a rotational spindle on the rotor.

[0025] According to a particular embodiment of the invention, during each oscillation cycle of the rotor, when the rotor vibrates between two extreme positions, the movable pawl drives the ratchet to rotate with the rotor relative to the stator in one direction, while when the rotor rotates in the opposite direction, the fixed pawl keeps the ratchet stationary.

[0026] According to a particular embodiment of the invention, the total rotation angle between the two extreme positions is less than half a turn, preferably less than a quarter turn or even less than an eighth turn, so that oscillations occur around the maximum magnet-coil torque.

[0027] According to a specific embodiment of the present invention, when in the rest position, the magnetization vector of the magnet is oriented substantially perpendicular to the principal axis of the magnetic flux Φ generated by the coil, so as to obtain the maximum magnet-coil torque.

[0028] According to a particular embodiment of the invention, the motor is configured to vibrate at its natural frequency to minimize power consumption, wherein the natural frequency is determined in particular by the inertia of the rotor and the resilient reset device.

[0029] The present invention also relates to a watch movement that includes such a vibrating motor. Attached Figure Description

[0030] The objects, advantages, and features of the invention will become apparent from reading several embodiments provided by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0031] - Figure 1 A partial perspective view of a vibrating motor, particularly for a watch movement, according to a first embodiment of the present invention is shown schematically.

[0032] - Figure 2 Schematic illustration Figure 1 A partial top view of the vibratory motor in the image.

[0033] - Figure 3 A schematic cross-sectional view of a vibration motor according to a second embodiment of the present invention is shown.

[0034] - Figure 4 Schematic illustration Figure 3 A top view of the vibrating motor in the image.

[0035] - Figure 5 a) and 5b) show the two steps of the ratchet's operation.

[0036] - Figure 6 This is a timing diagram of the vibration motor according to the present invention.

[0037] - Figure 7 The magnet and coil of the electric motor according to the present invention are schematically shown, as well as

[0038] - Figure 8 It shows a graph of the magnet-coil torque, which varies with the rotor angle on the vibratory motor according to the present invention. Detailed Implementation

[0039] Figure 1 and Figure 2 A schematic illustration of a first embodiment of a vibration motor 1 according to the present invention is shown, wherein flexible blades arranged in a cross shape constitute a flexible guide mechanism. This motor 1 can be used, for example, as an actuator in a watch movement, particularly for driving a gear train that in turn actuates, for example, a display device with hands.

[0040] The motor 1 includes a rotor 2 and a stator 3, with the rotor 2 rotatably mounted inside the fixed stator 3. The rotor 2 is equipped with permanent magnets and includes a cylindrical body, typically a plastic-coated part of the magnets. The stator 3 includes a body with a circular through-hole to allow the rotor 2 to be positioned therein. The stator 3 is equipped with one or more coils for actuating the rotor 2.

[0041] On one hand, the rotor 2 includes an axial spindle 12, which extends from axial disks arranged on the upper and lower sides of the cylinder of the rotor 2 to the top of the cylindrical body.

[0042] The motor 1 also includes a meshing pinion 15 mounted on the rotor 2. The meshing pinion 15 is rotatably attached to the rotor 2, particularly rotatable in a first direction of rotation of the rotor 2, but it can also pivot freely about the axial spindle 12 of the rotor 2 above the cylindrical body, particularly in a second direction of rotation of the rotor 2.

[0043] This meshing pinion 15 can mesh with, for example, a gear train (not shown) in a watch movement.

[0044] When the rotor 2 vibrates between two extreme positions due to being actuated by the coil, the meshing pinion 15 can rotate relative to the stator 3 in a first direction.

[0045] Therefore, the working principle of motor 1 is to generate each step of motor 1 by rotating and oscillating the rotor 2 between two extreme positions.

[0046] Therefore, according to the present invention, the motor 1 includes an elastic device for returning the rotor 2 from the extreme position to the rest position when the rotor 2 is no longer actuated by the coil. Preferably, the rest position is located at an intermediate position between the two extreme positions.

[0047] The reset device includes a flexible guide mechanism 5, which is arranged to suspend the rotor 2 and guide the rotor 2 to rotate, and apply force to return the rotor 2 to its rest position.

[0048] The flexible guide mechanism 5 includes a static element 27 attached to the stator 3 and a dynamic element 28 attached to the rotor 2. The static element 27 and the dynamic element 28 are connected by an elastic reset device.

[0049] In this example, the static element 27 includes two plates 7 and 8, which are assembled to be stacked on the stator 3, with the first plate 7 located above the stator 3 and the second plate 8 located below the stator 3.

[0050] exist Figure 1 and Figure 2 In the first embodiment shown, referred to as "cross-shaped," the dynamic element comprises two disk portions 9 and 11, which are partially open, with one portion 9 stacked above the rotor 2 and the other portion 11 arranged below the rotor 2. Each disk portion 9 and 11 includes two inner flanges 16, which are connected to the rotor 2 and joined together by an arcuate section 17.

[0051] The flexible guide mechanism 5 includes an upper flexible portion 14 connected to the top of the rotor 2 above the stator 3, and a lower flexible portion 19 connected to the bottom of the rotor 2 below the stator 3.

[0052] Preferably, the upper flexible portion 14 and the lower flexible portion 19 are substantially the same.

[0053] The upper flexible section 14 and / or the lower flexible section 19 include at least one pair of non-crossing flexible blades 20, preferably two pairs of non-crossing flexible blades 20, 21, which are arranged above the rotor 2.

[0054] The two pairs of flexible blades 20 and 21 are connected by a central annular portion 13 arranged around the spindle 12 of the rotor 2. The two pairs of flexible blades 20 and 21 are symmetrically arranged on both sides of the central annular portion 13. The first pair of flexible blades 20 connects the central annular portion 13 to the static element (top plate 7 or bottom plate 8 in this example), and the second pair of flexible blades 21 connects the central annular portion 13 to the dynamic element (disc portion 9 in this example).

[0055] Figure 3 and Figure 4 A second embodiment of the motor 1 according to the invention is shown, wherein the flexible blades of the flexible guide mechanism 5 are arranged in a different configuration, referred to as an in-line arrangement. There are no functional differences between these embodiments, as they all enable the rotor 2 to be guided to rotate.

[0056] The upper flexible portion 14 and / or lower flexible portion 19 of the flexible guide mechanism 5 include at least two parallel flexible blades 22 and 23. These two flexible blades 22 and 23 are symmetrically arranged on the rotor 2, and are connected to the central annular portion 24 on one hand and the upper plate 7 or lower plate 8 of the static element 27 on the other hand through the two pairs of flexible blades 19. The central annular portion 24 is concentrically assembled above or below the rotor 2.

[0057] When rotor 2 is in the rest position, the two flexible blades 22 and 23 are basically collinear.

[0058] Therefore, in both embodiments, when the rotor 2 is no longer actuated by the coil, the flexible guide mechanism 5 returns the rotor 2 from the extreme position to the rest position.

[0059] When the rotor 2 is in the rest position of the flexible guide mechanism 5, the flexible blades on the flexible guide mechanism 5 are basically straight. On the other hand, when the rotor 2 is in the actuated position, the blades on the flexible guide mechanism 5 are bent because they are subjected to stress generated by the position of the rotor 2 relative to the stator 3.

[0060] Preferably, the angular stroke of rotor 2 is selected to be less than half a turn, or even less than a quarter turn or an eighth turn, in order to ensure the efficiency of the magnet-coil torque, as described below.

[0061] exist Figure 4 and Figure 5 In this motor 1, a check ratchet 25 is also attached to the engagement pinion 15 to lock the engagement pinion 15 in a second rotational direction of the rotor. Preferably, the ratchet 25 is located only on the upper flexible portion 14 of the motor.

[0062] Two retaining pawls 26f are arranged on the upper flexible part 14 and attached to the stator 3, specifically the upper plate 8 mounted on the stator 3. The check ratchet 25 is locked in one direction by the retaining pawls 26f.

[0063] The movable pawl 26m is assembled onto the rotor 2 and rotates together with the rotor 2.

[0064] In the first rotational direction of rotor 2, the meshing pinion 15 and ratchet 25 are attached to rotor 2 (i.e., can rotate together with rotor 2), while in the second rotational direction of rotor 2, the meshing pinion 15 and ratchet 25 are assembled to be able to pivot freely about the rotational spindle 12 on rotor 2.

[0065] The working principle of motor 1, especially ratchet 25, is as follows: Figure 5 As shown in the diagram, when rotor 2 vibrates, it reciprocates according to a sinusoidal time function.

[0066] During the forward movement A in the first direction, the ratchet 25, and thus the engaging pinion 15, rotates with the rotor 2 relative to the stator 3 under the drive of the movable pawl 26m, while the fixed pawl 26f is reset by the rotation of the ratchet 25. The ratchet 25 has thus moved one step.

[0067] During the return motion B in the second opposite direction, ratchet 25 is locked by its fixed pawl 26f, while the movable pawl 26m is reset due to the locking of ratchet 25. Therefore, ratchet 25 remains stationary during the return motion B. In this way, ratchet 25 completes a step of one tooth in each oscillation cycle of rotor 2.

[0068] The meshing pinion 15 follows the movement of the ratchet 25. Therefore, the meshing pinion 15 rotates in a stepwise manner in the same direction.

[0069] exist Figure 6 In the curve graph, the first function F(2) represents the change of the oscillation angle θ of rotor 2 with time. The second function F(25) represents the change of the rotation angle of ratchet 25 with time. Due to the action of pawl 26, even if rotor 2 returns, ratchet 25 will continue to rotate in the same direction. Therefore, with each oscillation of rotor 2 in one direction, function F(25) increases by one level.

[0070] Figure 7 A more complete view of the motor 1 is shown. The stator 3 is a generally square ring with a groove on one side for receiving the rotor 2, and the stator 3 also includes a coil 31, which is at least partially wound on the other side of the stator 3. The rotor 2 is arranged in the groove and includes a magnet 32.

[0071] When coil 31 is actuated, rotor 2 oscillates around an angle of 0° corresponding to the rest position between two extreme positions with angles of -θ0 and +θ0.

[0072] Figure 8 The torque of motor 1 is shown as a function of rotation angle θ. When rotor 2 is in the rest position (θ=0), the magnetization vector of magnet 2 is substantially perpendicular to the principal axis orientation of the magnetic flux Φ generated by coil 31 in stator 3. When motor 1 is powered by AC voltage, rotor 2 vibrates between two extreme positions -θ0 and +θ0.

[0073] Ideally, the total angle covered by this angular range is less than half a turn, preferably less than a quarter turn or even an eighth turn. This ensures that the two extreme positions are close to the maximum magnet-coil torque, resulting in high electromechanical efficiency for this motor 1.

[0074] Preferably, the motor 1 is configured to vibrate at its natural frequency to minimize power consumption. The natural frequency of the motor 1 is determined by the inertia of the rotor 2 and the elastic reset device.

[0075] Of course, the present invention is not limited to the embodiments of the vibration motor described with reference to the accompanying drawings, and various modifications are conceivable without departing from the scope of the invention.

Claims

1. A vibratory motor (1) specifically for use in watch movements, the vibratory motor (1) comprising a rotor (2) equipped with a magnet (32) and a stator (3) equipped with at least one coil (31) capable of actuating the rotor (2) to rotate, wherein when the rotor (2) is actuated by the coil (31), the rotor (2) rotates relative to the stator (3) and oscillates between two extreme positions, characterized in that, The vibration motor includes an elastic reset device for resetting the rotor (2) between two extreme positions and an intermediate rest position when the rotor (2) is no longer actuated by the coil (31); the vibration motor (1) generates each step by the rotational oscillation motion of the rotor (2).

2. The vibration motor according to claim 1, characterized in that, The elastic reset device includes a flexible guide mechanism (5) arranged to suspend the rotor (2) on the stator (3).

3. The vibration motor according to claim 2, characterized in that, The flexible guide mechanism (5) includes an upper flexible portion (14) connected to the top of the rotor (2) above the stator (3), and a lower flexible portion (19) connected to the bottom of the rotor (2) below the stator (3).

4. The vibration motor according to claim 3, characterized in that, The upper flexible part (14) and / or lower flexible part (19) of the flexible guide mechanism (5) includes at least one pair of non-crossing flexible blades (20), preferably two pairs of non-crossing flexible blades (20, 21) arranged in series.

5. The vibration motor according to claim 2, characterized in that, The upper flexible part (14) and / or lower flexible part (19) of the flexible guide mechanism (5) includes at least one single flexible blade (22), preferably two single flexible blades (22, 23) arranged on both sides of the annular part, and the two single flexible blades are preferably collinear.

6. The vibration motor according to claim 4 or 5, characterized in that, The flexible guide mechanism (5) includes a static element (27) attached to the stator (3) and a dynamic element (28) attached to the rotor (2), the static element (27) and the dynamic element (28) being connected by flexible blades on the flexible guide mechanism (5).

7. The vibration motor according to claims 4 and 6, characterized in that, The flexible guide mechanism (5) includes an intermediate annular portion (13) arranged around a rotating spindle (12) on the rotor (2), wherein in the two pairs of flexible blades (20, 21), the first pair of flexible blades (20) connects the intermediate annular portion (13) to the dynamic element (28), and the other pair of flexible blades (21) connects the intermediate annular portion (13) to the static element (27).

8. The vibration motor according to claim 7, characterized in that, The two pairs of flexible blades (20, 21) are symmetrically arranged on both sides of the middle annular portion (13).

9. The vibration motor according to claims 5 and 6, characterized in that, The flexible guide mechanism (5) includes a central annular portion (24) arranged around a rotating spindle on the rotor (2), wherein in the two single flexible blades, a first single flexible blade (20) connects the central annular portion (24) to the dynamic element, and the other single flexible blade connects the central annular portion (24) to the static element (27).

10. The vibration motor according to any one of the preceding claims, characterized in that, The vibration motor (1) includes a meshing pinion (15) for meshing with a gear train, particularly a gear train in a watch movement, the meshing pinion (15) being pivotally mounted above the rotor (2).

11. The vibration motor according to claim 10, characterized in that, The vibration motor includes a ratchet (25) with a check pawl attached to the engagement pinion (15); the vibration motor also includes a movable pawl (26m) mounted on the rotor (2) and a fixed pawl (26f) mounted on the stator (3).

12. The vibration motor according to claims 10 and 11, characterized in that, In the first rotational direction of the rotor (2), the meshing pinion (15) and the ratchet (25) are attached to the rotor (2), while in the second rotational direction of the rotor (2), the meshing pinion (15) and the ratchet (25) are assembled to pivot freely about the rotational spindle (12) on the rotor (2).

13. The vibration motor according to claim 12, characterized in that, During each oscillation cycle of the rotor (2), when the rotor (2) vibrates between two extreme positions, the movable pawl (26m) drives the ratchet (25) to rotate with the rotor (2) relative to the stator (3) in one direction, while when the rotor (2) rotates in the opposite direction, the fixed pawl (26f) keeps the ratchet (25) stationary.

14. The vibration motor according to any one of the preceding claims, characterized in that, The total rotation angle between the two extreme positions is less than half a turn, preferably less than a quarter turn or even less than an eighth turn, so that oscillations occur around the maximum magnet-coil torque.

15. The vibration motor according to any one of the preceding claims, characterized in that, When in the resting position, the magnetization vector of the magnet (32) is substantially perpendicular to the principal axis orientation of the magnetic flux Φ generated by the coil (31) in order to obtain the maximum magnet-coil torque.

16. The vibration motor according to any one of the preceding claims, characterized in that, The vibration motor is configured to vibrate at its natural frequency in order to minimize power consumption, wherein the natural frequency is determined in particular by the inertia of the rotor (2) and the elastic reset device.

17. A watch movement, characterized in that, The watch movement includes a vibration motor (1) according to any one of the preceding claims.

Images