CN215120517U - Stepping motor - Google Patents

Abstract

The utility model provides a step motor. An improvement in the stop position accuracy of the rotor is achieved by controlling the braking torque in the stepping motor. The stepping motor has: a rotor (10) rotatably supported; a permanent magnet (14) provided on the rotor (10) and having a plurality of N poles and S poles alternately arranged at equal intervals in the rotational direction of the rotor (10); a 1 st stator having a 1 st winding surrounding a part of the permanent magnet (14) and a 1 st yoke housing the 1 st winding; a 2 nd stator having a 2 nd winding surrounding the other part of the permanent magnet (14) and a 2 nd yoke housing the 2 nd winding; and a magnetic plate (40) that surrounds the other part of the permanent magnet (14). Further, protrusions (41, 42) protruding toward the permanent magnet (14) are integrally formed on the magnetic plate (40).

Description

Stepping motor

Technical Field

The present invention relates to a stepping motor that can be used as a drive source of a constant displacement pump or a lens mechanism.

Background

The stepping motor has a stator and a rotor. The stator is provided with a plurality of windings divided into 2 or more phases, and the rotor is provided with a plurality of magnets. When the current (excitation current) supplied to the windings of each phase is switched in a predetermined pattern, the rotor rotates by a predetermined rotation angle (basic pitch angle) each time.

The stepping motor having the basic structure and the basic operation as described above can realize accurate speed control and position control without performing feedback control using a speed sensor, a position sensor, or the like. Therefore, the stepping motor is suitable for a drive source of a constant displacement pump such as a liquid pump and a drive source of a lens mechanism of a camera, which require high-precision speed control and position control, in addition to being small and lightweight.

Patent document 1: japanese patent laid-open publication No. 2015-61351

In a stepping motor of PM (Permanent Magnet) type or HB (Hybrid) type using a Permanent Magnet for a rotor, the following properties are exhibited: the rotor is intended to be always held at the stop position by the attraction force of the permanent magnet provided on the rotor. Such a force (torque) intended to hold the rotor at the stop position is sometimes referred to as "braking torque". Therefore, in the present specification, the torque caused by the attraction force of the permanent magnet provided to the rotor, that is, the torque intended to hold the rotor at the stop position is also referred to as "braking torque".

As described above, the braking torque is a force intended to hold the rotor at the stop position. Therefore, if the same braking torque is always generated for each basic pitch angle, the stop position accuracy of the rotor is improved. For example, in a stepping motor with a basic pitch angle of 18 degrees, 1 rotation (360 degrees) of the rotor is divided into 20 parts (360/18). I.e. the rotor is rotated 18 degrees with respect to 1 pulse of the excitation current. Therefore, if the same or substantially the same braking torque can be always generated at 18 degrees, the stop position accuracy of the rotor can be improved. In other words, if the same or substantially the same braking torque can be generated 20 times during 1 rotation of the rotor, the stop position accuracy of the rotor can be improved. However, due to manufacturing errors and the like, the same or substantially the same braking torque is not always easily generated.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to, realize the improvement of the stop position precision of rotor through the braking moment of torsion among the control step motor.

The utility model discloses a mode 1 provides a step motor, its characterized in that, this step motor has: a rotor supported to be rotatable; a permanent magnet provided on the rotor and having a plurality of N poles and S poles alternately arranged at equal intervals in a rotation direction of the rotor; a 1 st stator having a 1 st winding surrounding a part of the permanent magnet and a 1 st yoke housing the 1 st winding; a 2 nd stator having a 2 nd winding surrounding the other part of the permanent magnets and a 2 nd yoke housing the 2 nd winding; and a magnetic plate surrounding the other part of the permanent magnet. Further, a protrusion protruding toward the permanent magnet is integrally formed on the magnetic plate.

In one aspect of the present invention, the 1 st stator and the 2 nd stator are aligned in a line along the rotation axis of the rotor, and the magnetic material plate is disposed between the 1 st stator and the 2 nd stator.

In another aspect of the present invention, the 1 st yoke includes: an inner member interposed between the 1 st winding and the permanent magnet, and having a plurality of 1 st magnetic pole teeth arranged at regular intervals in a rotation direction of the rotor; and an outer member interposed between the 1 st winding and the permanent magnet, and having a plurality of 2 nd magnetic pole teeth arranged at the same intervals as the 1 st magnetic pole teeth in a rotation direction of the rotor. Further, the 2 nd yoke includes: an inner member interposed between the 2 nd winding and the permanent magnet, and having a plurality of 1 st magnetic pole teeth arranged at regular intervals in a rotation direction of the rotor; and an outer member interposed between the 2 nd winding and the permanent magnet, and having a plurality of 2 nd magnetic pole teeth arranged at the same intervals as the 1 st magnetic pole teeth in a rotation direction of the rotor. Also, the magnetic plate is sandwiched between the inner member of the 1 st yoke and the inner member of the 2 nd yoke.

In another aspect of the present invention, the magnetic plate has a ring shape, and the protrusion protrudes from an inner peripheral edge of the magnetic plate toward an outer peripheral surface of the permanent magnet.

In another aspect of the present invention, the projection of the magnetic plate is opposed to an arbitrary position of a set of adjacent N-pole and S-pole of the permanent magnet at an arbitrary stop position of the rotor.

In another aspect of the present invention, the magnetic plate is integrally formed with two of the projections separated in a rotation direction of the rotor. Also, the separation angle θ of the two protrusions is a multiple of the basic pitch angle of the rotor (where 0 < θ < 360).

In another aspect of the present invention, the basic step angle is 18 degrees, and the separation angle θ is 90 degrees.

According to the utility model discloses, realized the step motor that the stop position precision of rotor is high.

Drawings

Fig. 1 is a perspective view showing an appearance of a stepping motor to which the present invention is applied.

Fig. 2 is a sectional view showing the overall configuration of the stepping motor shown in fig. 1.

Fig. 3 is a perspective view, partially in section, showing the configuration of the front stator and the rear stator shown in fig. 2.

Fig. 4 is a perspective view illustrating the configuration of the front and rear yokes illustrated in fig. 3.

Fig. 5A is a perspective view showing the magnetic plate, and fig. 5B is a plan view showing the magnetic plate.

Fig. 6A to 6D are explanatory diagrams showing a positional relationship between the pair of magnetic poles of the permanent magnet and the projection of the magnetic plate at different stop positions of the rotor.

Description of the reference symbols

1: a stepping motor; 2: a connection terminal; 10: a rotor; 11: a shaft; 12a, 12 b: a side plate; 13a, 13 b: a bearing; 14: a permanent magnet; 20: 1 st stator (front stator); 21: winding No. 1 (front winding); 22: 1 st coil bobbin (front coil bobbin); 23: the 1 st yoke (front yoke); 23a, 33 a: an inner part; 23b, 33 b: an outer member; 24. 34: 1 st magnetic pole tooth; 25. 35: a 2 nd magnetic pole tooth; 30: a 2 nd stator (rear stator); 31: 2 nd winding (rear winding); 32: 2 nd coil bobbin (rear coil bobbin); 33: a 2 nd yoke (rear yoke); 40: a magnetic plate; 41. 42: a protrusion; x: a rotation axis; θ: the angle of separation.

Detailed Description

Hereinafter, an example of an embodiment of a stepping motor according to the present invention will be described in detail with reference to the drawings. As shown in fig. 1 and 2, the stepping motor 1 of the present embodiment has a substantially cylindrical outer appearance as a whole. When power is supplied to the illustrated connection terminals 2 and 3, the rotor 10 including the shaft 11 rotates about the rotation axis X. One end side of the shaft 11 is rotatably supported by a bearing 13a fixed to a disc-shaped side plate 12 a. On the other hand, the other end side of the shaft 11 is rotatably supported by a bearing 13b fixed to a disc-shaped side plate 12 b.

In the following description, the longitudinal direction of the shaft 11 shown in fig. 1 and 2 is referred to as the front-rear direction or the axial direction. One end side of the shaft 11 supported by the bearing 13a is referred to as "front", and the other end side of the shaft 11 supported by the bearing 13b is referred to as "rear".

As shown in fig. 2, the rotor 10 includes a permanent magnet 14 in addition to the shaft 11. The permanent magnet 14 has a cylindrical shape, and the shaft 11 penetrates the center of the permanent magnet 14 in the front-rear direction. The shaft 11 and the permanent magnet 14 are fixed so as not to be rotatable relative to each other. The permanent magnet 14 has a plurality of N poles and S poles alternately arranged at equal intervals in the rotation direction of the rotor 10. In other words, the permanent magnets 14 are alternately magnetized into N-poles and S-poles at equal intervals along the rotation direction of the rotor 10. More specifically, the permanent magnet 14 of the present embodiment is provided with 5N poles and 5S poles, respectively. That is, the number of poles of the permanent magnet 14 in the present embodiment is 10.

As shown in fig. 1 and 2, a 1 st stator 20 and a 2 nd stator 30 are provided around the rotor 10 so as to surround the permanent magnets 14. The 1 st stator 20 and the 2 nd stator 30 are aligned in a row along the rotation axis X of the rotor 10. In other words, the 1 st stator 20 and the 2 nd stator 30 are arranged in a row in tandem.

As shown in fig. 2, the 1 st stator 20 surrounds a portion of the permanent magnet 14, and the 2 nd stator 30 surrounds another portion of the permanent magnet 14. Specifically, the 1 st stator 20 surrounds substantially the front half of the permanent magnet 14, and the 2 nd stator 30 surrounds substantially the rear half of the permanent magnet 14. Therefore, in the following description, the 1 st stator 20 may be referred to as a "front stator 20", and the 2 nd stator 30 may be referred to as a "rear stator 30". In addition, a part of the permanent magnet 14 surrounded by the front stator 20 may be referred to as a "front part", another part of the permanent magnet 14 surrounded by the rear stator 30 may be referred to as a "rear part", and another part of the permanent magnet 14 not surrounded by either the front stator 20 or the rear stator 30 may be referred to as an "intermediate part". However, this distinction is merely a distinction for convenience of explanation.

As shown in fig. 2, the front stator 20 includes: a 1 st coil bobbin 22 around which a 1 st winding 21 to which an excitation current is supplied is wound; and a 1 st yoke 23 that houses the 1 st coil bobbin 22. The 1 st yoke 23 is composed of an inner member 23a and an outer member 23 b. In the following description, the "1 st winding 21", the "1 st coil bobbin 22", and the "1 st yoke 23" are referred to as a "front winding 21", a "front coil bobbin 22", and a "front yoke 23", respectively. The front coil bobbin 22 is formed of an insulator such as resin, and the front yoke 23 (inner member 23a and outer member 23b) is formed of a magnetic body.

As shown in fig. 2 and 3, the inner member 23a of the front yoke 23 is interposed between the front winding 21 and the permanent magnet 14, and has a plurality of (5) 1 st magnetic pole teeth 24 arranged at regular intervals in the rotation direction of the rotor 10 (i.e., the circumferential direction of the permanent magnet 14). On the other hand, the outer member 23b of the front yoke 23 is interposed between the front winding 21 and the permanent magnet 14, and has a plurality of (5) 2 nd magnetic pole teeth 25 arranged at the same intervals as the 1 st magnetic pole teeth 24 in the rotation direction of the rotor 10.

More specifically, the 1 st magnetic pole tooth 24 and the 2 nd magnetic pole tooth 25 are interposed between the front coil bobbin 22 around which the front winding 21 is wound and the front portion of the permanent magnet 14. That is, 10 1 st magnetic pole teeth 24 and 2 nd magnetic pole teeth 25 are alternately arranged at equal intervals along the rotation direction of the rotor 10 in the annular space between the front coil bobbin 22 and the front portions of the permanent magnets 14. The 1 st magnetic pole tooth 24 extends forward from the inner member 23a, and the 2 nd magnetic pole tooth 25 extends rearward from the outer member 23 b.

Refer to fig. 4. The interval (P1a) between the adjacent 21 st magnetic pole teeth 24 is 72 degrees. The interval (P1b) between the 2 nd adjacent magnetic pole teeth 25 is also 72 degrees. Therefore, the interval (P2) between the 1 st magnetic pole tooth 24 and the 2 nd magnetic pole tooth 25 which are alternately arranged is 36 degrees.

As shown in fig. 2, the rear stator 30 includes: a 2 nd coil bobbin 32 around which a 2 nd winding 31 to which an excitation current is supplied is wound; and a 2 nd yoke 33 that receives the 2 nd coil bobbin 32. The 2 nd yoke 33 is composed of an inner member 33a and an outer member 33 b. In the following description, the "2 nd winding 31", the "2 nd coil bobbin 32", and the "2 nd yoke 33" are referred to as "the rear winding 31", the "rear coil bobbin 32", and the "rear yoke 33", respectively. The rear coil bobbin 32 is formed of an insulator such as resin, and the rear yoke 33 (the inner member 33a and the outer member 33b) is formed of a magnetic body.

As shown in fig. 2 and 3, the inner member 33a of the rear yoke 33 is interposed between the rear winding 31 and the permanent magnet 14, and has a plurality of (5) 1 st magnetic pole teeth 34 arranged at regular intervals in the rotation direction of the rotor 10. On the other hand, the outer member 33b of the rear yoke 33 is interposed between the rear winding 31 and the permanent magnet 14, and has a plurality of (5) 2 nd magnetic pole teeth 35 arranged at the same intervals as the 1 st magnetic pole teeth 34 in the rotational direction of the rotor 10.

More specifically, the 1 st and 2 nd magnetic pole teeth 34 and 35 are interposed between the rear coil bobbin 32 around which the rear winding 31 is wound and the rear portion of the permanent magnet 14. That is, 10 1 st magnetic pole teeth 34 and 2 nd magnetic pole teeth 35 are alternately arranged at equal intervals in the rotation direction of the rotor 10 in the annular space between the rear coil bobbin 32 and the rear portion of the permanent magnet 14. The 1 st magnetic pole tooth 34 extends rearward from the inner member 33a, and the 2 nd magnetic pole tooth 35 extends forward from the outer member 33 b.

Reference is again made to fig. 4. The interval (P1a) between the adjacent 21 st magnetic pole teeth 34 is 72 degrees. The interval (P1b) between the 2 nd adjacent magnetic pole teeth 35 is also 72 degrees. Therefore, the interval (P2) between the 1 st magnetic pole tooth 34 and the 2 nd magnetic pole tooth 35 which are alternately arranged is 36 degrees.

As described above, 10 magnetic pole teeth are provided on the front yoke 23 and the rear yoke 33, respectively. That is, the number N of magnetic pole teeth of the stepping motor 1 of the present embodiment is 20. The 1 st magnetic pole tooth 24 of the front yoke 23 and the 1 st magnetic pole tooth 34 of the rear yoke 33 are shifted by 360 degrees/N (360 degrees/20 degrees or 18 degrees) in the rotational direction of the rotor 10. The 2 nd magnetic pole tooth 25 of the front yoke 23 and the 2 nd magnetic pole tooth 35 of the rear yoke 33 are shifted by 360 degrees/N (360 degrees/20 degrees or 18 degrees) in the rotational direction of the rotor 10. The offset angle (18 degrees) between the respective pole teeth corresponds to the basic pitch angle of the rotor 10. That is, the basic pitch angle of the rotor 10 in the stepping motor 1 of the present embodiment is 18 degrees. The basic pitch angle (18 degrees) of the rotor 10 is also an angle corresponding to P2/2.

As shown in fig. 1, a magnetic plate 40 is disposed between the front stator 20 and the rear stator 30. As shown in fig. 2 to 4, the magnetic plate 40 is disposed between the front yoke 23 and the rear yoke 33. More specifically, the magnetic plate 40 is disposed between the inner member 23a of the front yoke 23 and the inner member 33a of the rear yoke 33. In other words, the inner member 23a of the front yoke 23 and the inner member 33a of the rear yoke 33 sandwich the magnetic plate 40.

As shown in fig. 4, 5A, and 5B, the magnetic plate 40 has a ring shape. As shown in fig. 2 and 5A, the magnetic plate 40 surrounds the middle portion of the permanent magnet 14. As shown in fig. 5A and 5B, 2 projections 41 and 42 projecting toward the permanent magnet 14 are integrally formed on the magnetic plate 40. The protrusions 41 and 42 protrude from the inner peripheral edge of the magnetic plate 40 toward the outer peripheral surface of the permanent magnet 14. However, a slight gap (air gap) is provided between the end surfaces of the protrusions 41 and 42 and the outer peripheral surface of the permanent magnet 14.

As shown in fig. 5B, the 2 protrusions 41, 42 provided on the magnetic plate 40 are separated in the rotation direction of the rotor 10. Specifically, the separation angle θ of the 2 protrusions 41 and 42 in the rotation direction of the rotor 10 is a multiple of the basic pitch angle of the rotor 10 (where 0 < θ < 360), and is 90 degrees in the present embodiment. In other words, when the end face of the rotor 10 shown in fig. 5B is regarded as the dial of the timepiece, the projection 41 is located at 12 o 'clock, and the projection 42 is located at 3 o' clock.

In the stepping motor 1 of the present embodiment in which the arrangement of the 2 projections 41 and 42 satisfies the above-described condition, at an arbitrary stop position of the rotor 10, the projection 41 or the projection 42 faces an arbitrary position of a set of adjacent N-pole and S-pole of the permanent magnet 14. Hereinafter, the description will be more specifically made with reference to fig. 6A to 6D. In the following description, the position of the rotor 10 (permanent magnet 14) shown in fig. 6A is set as a reference position (rotation angle 0 degrees). Further, the rotor 10 (permanent magnet 14) shown in fig. 6A rotates clockwise from the reference position shown in the figure.

As described above, the basic pitch angle of the rotor 10 in the stepping motor 1 of the present embodiment is 18 degrees. Therefore, the rotor 10 (permanent magnet 14) shown in fig. 6A rotates 1 rotation at 18 degrees clockwise from the illustrated reference position.

As shown in fig. 6A, when the rotor 10 (permanent magnet 14) is located at the reference position, the projection 41 faces the N-pole and S-pole of the adjacent pair of permanent magnets 14. More strictly, the protrusion 41 is opposed to the boundary of an adjacent set of N pole and S pole.

Then, when the rotor 10 (permanent magnet 14) shown in fig. 6A rotates by 18 degrees and reaches the stop position shown in fig. 6B, the projection 42 faces the other adjacent group of N poles and S poles of the permanent magnet 14. Next, when the rotor 10 (permanent magnet 14) shown in fig. 6B is further rotated by 18 degrees (accumulated by 36 degrees) and reaches the stop position shown in fig. 6C, the projection 41 faces another adjacent group of N poles and S poles of the permanent magnet 14. Then, when the rotor 10 (permanent magnet 14) shown in fig. 6C is further rotated by 18 degrees (accumulated by 54 degrees) to reach the stop position shown in fig. 6D, the projection 42 is opposed to the adjacent other group of N poles and S poles of the permanent magnet 14. Thereafter, one of the projections 41 or 42 faces any position of the adjacent pair of N-pole and S-pole at 18-degree intervals until the rotation angle of the rotor 10 (permanent magnet 14) reaches 360 degrees.

Here, the projections 41 and 42 provided on the magnetic plate 40 are integrally formed with the magnetic plate 40. That is, at each stop position of the rotor 10, a magnetic substance that does not exist in the vicinity of any one set of the magnetic pole pairs of the permanent magnets 14 exists in the vicinity of the other magnetic pole pairs. As a result, the magnetic field strength between the pair of magnetic poles facing the projection 41 or the projection 42 is increased compared to the magnetic field strength between the other pair of magnetic poles. The degree of enhancement of the magnetic field strength of the protrusions 41, 42 can be controlled by the size of the protrusions 41, 42, the size of the air gap between the protrusions 41, 42 and the permanent magnet 14, and the like. Thus, the same or substantially the same braking torque can always be generated at the basic pitch angle (18 degrees) of the rotor 10. In other words, the same or substantially the same braking torque can be generated a predetermined number of times during 1 rotation of the rotor 10. Therefore, the rotor 10 is reliably stopped at the basic pitch angle, and the stop position accuracy of the rotor 10 is improved. Further, by always generating the same or substantially the same braking torque, it is also possible to expect an increase in output torque and a reduction in vibration and noise.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, the number and arrangement of the protrusions provided on the magnetic plate can be changed as appropriate according to the basic pitch angle of the rotor. The size of the projection provided on the magnetic plate and the size of the air gap between the projection and the permanent magnet can be appropriately changed according to the desired braking torque. The front yoke, the rear yoke, and the magnetic plate may be formed of the same magnetic material or different magnetic materials.

The position of the magnetic plate in the front-rear direction is not limited to the position (between the front yoke and the rear yoke) in the above embodiment. For example, the magnetic plate may be disposed in front of the front yoke so as to surround the permanent magnet, may be disposed behind the rear yoke, or may be disposed in another position.

Claims (7)

1. A stepping motor is characterized in that a motor body,

the stepping motor has:

a rotor supported to be rotatable;

a permanent magnet provided on the rotor and having a plurality of N poles and S poles alternately arranged at equal intervals in a rotation direction of the rotor;

a 1 st stator having a 1 st winding surrounding a part of the permanent magnet and a 1 st yoke housing the 1 st winding;

a 2 nd stator having a 2 nd winding surrounding the other part of the permanent magnets and a 2 nd yoke housing the 2 nd winding; and

a magnetic plate surrounding the other part of the permanent magnet,

a protrusion protruding toward the permanent magnet is integrally formed on the magnetic plate.

2. The stepping motor according to claim 1,

the 1 st stator and the 2 nd stator are arranged in a line along the rotational axis of the rotor,

the magnetic material plate is disposed between the 1 st stator and the 2 nd stator.

3. The stepping motor according to claim 2,

the 1 st yoke includes: an inner member interposed between the 1 st winding and the permanent magnet, and having a plurality of 1 st magnetic pole teeth arranged at regular intervals in a rotation direction of the rotor; and an outer member interposed between the 1 st winding and the permanent magnet, and having a plurality of 2 nd magnetic pole teeth arranged at the same intervals as the 1 st magnetic pole teeth in a rotation direction of the rotor,

the 2 nd yoke includes: an inner member interposed between the 2 nd winding and the permanent magnet, and having a plurality of 1 st magnetic pole teeth arranged at regular intervals in a rotation direction of the rotor; and an outer member interposed between the 2 nd winding and the permanent magnet, and having a plurality of 2 nd magnetic pole teeth arranged at the same intervals as the 1 st magnetic pole teeth in a rotation direction of the rotor,

the magnetic plate is sandwiched between the inner member of the 1 st yoke and the inner member of the 2 nd yoke.

4. The stepping motor according to any one of claims 1 to 3,

the magnetic plate is in a ring shape,

the protrusion protrudes from an inner peripheral edge of the magnetic plate toward an outer peripheral surface of the permanent magnet.

5. The stepping motor according to any one of claims 1 to 3,

the projection of the magnetic plate is opposed to an arbitrary position in an adjacent set of N-pole and S-pole of the permanent magnet at an arbitrary stop position of the rotor.

6. The stepping motor according to claim 5,

two protrusions separated in the rotation direction of the rotor are integrally formed on the magnetic plate,

the separation angle theta of the two protrusions is a multiple of the basic step angle of the rotor, wherein 0 < theta < 360.

7. The stepping motor according to claim 6,

the base step angle is 18 degrees and the separation angle θ is 90 degrees.

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