JP5623219B2 - motor - Google Patents

Description

  The present invention relates to a motor such as a stepping motor that detects a magnetic pole position of a rotor and controls switching of energization timing.

  In a motor such as a stepping motor, a technique is known in which a magnet rotor and a detection rotor are coaxially disposed on a motor shaft, and a magnetic pole position of the detection rotor is detected by a magnetic conversion element such as a Hall element (Patent Document 1). ).

JP 2002-62162 A

  However, in Patent Document 1, since it is necessary to dispose the detection rotor on the motor shaft separately from the magnet rotor, the motor is increased in size and cost. In addition, in order to avoid an increase in the size and cost of the motor, even if an attempt is made to directly detect the magnetic pole position of the magnet rotor with the magnetic detection element, the so-called claw pole type stepping motor is arranged with the magnetic detection elements sufficiently close to each other. It is difficult to do this, and there is a problem that detection accuracy decreases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a motor that can easily increase the detection accuracy of the magnetic pole position of a rotor while reducing the size and cost.

To achieve the above object, motors of the present invention includes a rotor in which a plurality of magnetic poles in a circumferential direction are formed, is formed of a non-magnetic material, a lid member for covering the axial end face of the front SL rotor When the magnetic detection element, one end opposite to the axial end face of said rotor such that said magnetic sensor is disposed at the other end, magnetic properties shaft member supported on said lid member And a plurality of the magnetic shaft members are arranged at equal intervals in the circumferential direction around the rotor shaft, and among the plurality of magnetic shaft members, the other end of a part of the magnetic shaft members the magnetic sensor is characterized that you have arranged parts.

  ADVANTAGE OF THE INVENTION According to this invention, the detection accuracy of the magnetic pole position of a rotor can be raised easily, aiming at size reduction and cost reduction of a motor.

It is principal part sectional drawing of the claw pole type stepping motor which is an example of embodiment of this invention. It is the principal part side view which looked at FIG. 1 from the B phase cover member side. It is a typical sectional view for explaining phase relation of a B phase yoke, an A phase yoke, a magnetic detection element, and a magnet rotor. (A) is a graph which shows the relationship between the rotation angle of a magnet rotor, and a motor torque, (b) is a graph which shows the relationship between the rotation angle of a magnet rotor, and the sensor output of a magnetic detection element. It is a schematic sectional drawing for demonstrating operation | movement of feedback energization switching mode. It is principal part sectional drawing of the claw pole type stepping motor which is other embodiment of this invention.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a main part of a claw pole type stepping motor which is an example of an embodiment of the present invention.

  As shown in FIG. 1, in the stepping motor of this embodiment, an A-phase lid member 10 and a B-phase lid member 12 are fitted and held at both axial ends of an outer casing 9 made of a magnetic material. Yes. The B-phase lid member 12 is made of a nonmagnetic material such as polycarbonate resin, and corresponds to an example of the support member of the present invention. The A-phase lid member 10 and the B-phase lid member 12 are respectively provided with an A-phase bearing 11 and a B-phase bearing 13 substantially concentrically with the outer cylinder case 9, and the A-phase bearing 11 and the B-phase bearing 13 have A rotor shaft 2 of a magnet rotor 1 magnetized in the circumferential direction with 8 poles is rotatably supported.

  In the inner peripheral part of the outer cylinder case 9, the exciting coil 3 is supported on the B-phase lid member 12 side, and the exciting coil 4 is supported on the A-phase lid member 10 side. A pair of yokes 5 and 6 forming magnetic pole teeth are fixed to the exciting coil 3 so as to form a predetermined phase angle, and a pair of yokes 7 and 8 forming magnetic pole teeth are fixed to the exciting coil 4 with a predetermined phase. It is fixed to make an angle.

  The excitation coil 3, the pair of yokes 5, 6 and the outer cylinder case 9 form an excitation phase by a B-phase closed magnetic path, and the excitation coil 4, the pair of yokes 7, 8 and the outer cylinder case 9 form an A-phase closed magnetism. An excitation phase is formed by the path.

  Around the B-phase bearing 13 of the B-phase lid member 12, a plurality of magnetic shaft members 14 (an integer multiple of the number of magnetic poles of the magnet rotor 1: 16 in this embodiment) penetrate at substantially equal intervals in the circumferential direction. In this state, it is fixed by press-fitting or bonding.

  One end of the magnetic shaft member 14 faces the end surface 1a in the axial direction of the magnet rotor 1 through a certain air gap, and the other end faces the outer end surface 12a of the B-phase lid member 12. It is considered as one and is exposed to the outside. Magnetic detection elements 15 and 17 (see FIG. 2) mounted on the flexible circuit board 16 are fixed to the outer end surface 12a of the B-phase lid member 12. The magnetic detection elements 15 and 17 will be described later.

  Thus, by arranging the plurality of magnetic shaft members 14 at substantially equal intervals in the circumferential direction, the force (the left direction in FIG. 1) that the magnetic shaft member 14 attracts the magnet rotor 1 in the axial direction is the rotor shaft 2. It occurs periodically and evenly around. For this reason, the rotational resistance of the magnet rotor 1 becomes uniform with no deviation due to the rotational phase, and the occurrence of rotational fluctuations, vibrations, and the like can be eliminated.

  Further, since the magnet rotor 1 is rattled to the left in FIG. 1 by the attractive force with the magnetic shaft member 14, the air gap fluctuation between the magnet rotor 1 and the magnetic shaft member 14 due to vibration and backlash fluctuation caused by the backlash. Therefore, stable magnetic pole position detection can be performed.

  FIG. 2 is a side view of the main part when FIG. 1 is viewed from the B-phase lid member 12 side. In FIG. 2, the B-phase yoke 5 is schematically shown by a solid line, and the A-phase yoke 7 is schematically shown by a broken line.

  The magnet rotor 1 is stopped at the position shown in FIG. 2, and at this time, the center phase of the B-phase yoke 5 coincides with the N-pole magnetization peak position of the magnet rotor 1. In this state, the plurality of magnetic shaft members 14 are arranged at positions that coincide with the polarization position of the magnet rotor 1 and the magnetization peak position of the N or S pole.

  A magnetic detection element 15 and a magnetic detection element 17 are disposed on the end surfaces of the two magnetic shaft members 14a and 14b on the side exposed to the outer end surface 12a of the B-phase lid member 12, respectively. . The stepping motor is driven in a feedback energization switching mode in which energization is switched based on signals output from the magnetic detection element 15 and the magnetic detection element 17.

  Next, the energization switching control in the stepping motor of this embodiment will be described with reference to FIGS.

  FIG. 3 is a schematic cross-sectional view for explaining the phase relationship among the B-phase yoke 5, the A-phase yoke 7, the magnetic detection elements 15 and 17, and the magnet rotor 1. 3 and 5, the clockwise direction is a positive direction, and for convenience of explanation, the magnetic detection elements 15 and 17 are arranged on the outer peripheral side of the magnet rotor 1 for easy viewing. In the present embodiment, since the number of magnetic poles of the magnet rotor 1 is eight, the magnetization angle P is assumed to be 45 °.

  With reference to the B-phase yoke 5, the phase P / 2 of the A-phase yoke 7 is −22.5 °, the phase β1 of the magnetic detection element 15 is + 22.5 °, and the phase β2 of the magnetic detection element 17 is −45. °.

  Here, in the following description, it demonstrates using an electrical angle. The electrical angle is expressed by assuming that one period of the magnet magnetic force is 360 °. When the number of poles of the rotor is M and the actual angle is θ0, the electrical angle is expressed as θ = θ0 × M / 2.

  Therefore, the phase difference between the B phase yoke 5 and the A phase yoke 7, the phase difference between the magnetic detection element 15 and the magnetic detection element 17, and the phase difference between the B phase yoke 5 and the magnetic detection element 15 are all 90 in electrical angle. °. In FIG. 3, the magnetic pole tooth center of the B-phase yoke 5 and the N-pole center of the magnet rotor 1 are opposed to each other in the radial direction. This state is the initial state of the magnet rotor 1 and the electrical angle is 0 °.

  FIG. 4A is a graph showing the relationship between the rotation angle of the magnet rotor 1 and the motor torque, where the horizontal axis represents the electrical angle and the vertical axis represents the motor torque. The motor torque is positive when the magnet rotor 1 is rotated clockwise.

  When a positive current is passed through the exciting coil 3, the B-phase yoke 5 is magnetized to the N pole, and an electromagnetic force is generated between the magnet rotor 1 and the magnetic poles. In addition, when a positive current is passed through the exciting coil 4, the A-phase yoke 7 is magnetized to the N pole, and an electromagnetic force is generated between the magnetic poles of the magnet rotor 1. When these two electromagnetic forces are combined, a substantially sinusoidal torque is obtained as the magnet rotor 1 rotates (torque curve A + B +).

  Similarly, a substantially sinusoidal torque can be obtained in other energized states (torque curves A + B−, AB−, and AB−). Further, since the B-phase yoke 5 is arranged with a phase of 90 ° in electrical angle with respect to the A-phase yoke 7, the four torques have a phase difference of 90 ° in electrical angle.

  FIG. 4B is a graph showing the relationship between the rotation angle of the magnet rotor 1 and the sensor outputs of the magnetic detection elements 15 and 17, where the horizontal axis represents the electrical angle and the vertical axis represents the sensor output.

  The end surface 1a in the axial direction of the magnet rotor 1 is magnetized such that the strength of the magnetic force with respect to the electrical angle is substantially sinusoidal. Therefore, a substantially sinusoidal signal is obtained from the magnetic detection element 15 (sensor signal A).

  In the present embodiment, the magnetic detection element 15 outputs a positive value when facing the N pole of the magnet rotor 1 in the axial direction.

  Further, since the magnetic detection element 17 is arranged with a phase of 90 ° in electrical angle with respect to the magnetic detection element 15, a substantially cosine wave signal is obtained from the magnetic detection element 17 (sensor signal B).

  In the present embodiment, since the polarity of the magnetic detection element 17 is inverted with respect to the magnetic detection element 15, a positive value is output when facing the south pole of the magnet rotor 1 in the axial direction.

  Signals obtained by binarizing the sensor signal A and the sensor signal B are the binarized signal A and the binarized signal B. In the feedback energization switching mode, energization of the exciting coil 4 is switched based on the binarized signal A, and energization of the exciting coil 3 is switched based on the binarized signal B.

  That is, when the binarized signal A indicates a positive value, a current in the positive direction is supplied to the exciting coil 4, and when the binary signal A indicates a negative value, a current in the reverse direction is supplied to the exciting coil 4. Further, when the binarized signal B shows a positive value, a current in the positive direction is passed through the exciting coil 3, and when the binary signal B shows a negative value, a current in the reverse direction is sent through the exciting coil 3.

  FIG. 5 is a schematic cross-sectional view for explaining the operation in the feedback energization switching mode.

  FIG. 5A shows a state in which the magnet rotor 1 is rotated by 135 degrees in electrical angle. In this state, the sensor outputs of the magnetic detection elements 15 and 17 are the values indicated by X1 in FIG. 4B, and the binary signal A is positive and the binary signal B is negative.

  Accordingly, a forward current flows through the exciting coil 4 and the A-phase yoke 7 is magnetized to the N pole, and a reverse current flows through the exciting coil 3 and the B-phase yoke 5 is magnetized to the S pole. At this time, the clockwise torque corresponding to the torque curve A + B− in FIG. 4A acts, and the magnet rotor 1 rotates in response to the rotational force in the θ direction.

  FIG. 5B shows a state in which the magnet rotor 1 is rotated by 180 ° in electrical angle, and the magnetic detection element 15 is located at the boundary between the N pole and the S pole of the magnet rotor 1. For this reason, the binarized signal A is switched from a positive value to a negative value at an electrical angle of 180 °, and the energizing direction of the exciting coil 4 is switched from the positive direction to the reverse direction. This electrical angle coincides with the electrical angle at the intersection of the torque curve A + B− and the torque curve A−B− in FIG.

  FIG. 5B ′ shows a state in which the magnet rotor 1 is rotated by 180 ° in electrical angle and the energizing direction of the exciting coil 4 is switched. In this state, a reverse current flows through the excitation coil 4 and the A-phase yoke 7 is magnetized to the S pole, and a reverse current flows through the excitation coil 3 and the B-phase yoke 5 is magnetized to the S pole. To do. At this time, a clockwise torque corresponding to the torque curve AB in FIG. 4A acts, and the magnet rotor 1 rotates in response to the rotational force in the θ direction.

  FIG. 5C shows a state in which the magnet rotor 1 is rotated by 225 ° in electrical angle. In this state, the sensor outputs of the magnetic detection elements 15 and 17 indicate the value indicated by X3 in FIG. 4B, and the binary signal A is negative and the binary signal B is negative. .

  Therefore, a negative current flows through the exciting coil 4 and the A-phase yoke 7 is magnetized to the S pole, and a reverse current flows through the exciting coil 3 and the B-phase yoke 5 is magnetized to the S pole. At this time, a clockwise torque corresponding to the torque curve AB in FIG. 4A acts, and the magnet rotor 1 rotates in response to the rotational force in the θ direction.

  FIG. 5D shows a state where the magnet rotor 1 is rotated by 270 ° in electrical angle, and the magnetic detection element 17 is located at the boundary between the N pole and the S pole of the magnet rotor 1. For this reason, the binarized signal B is switched from a negative value to a positive value at the electrical angle of 270 °, and the energization direction of the exciting coil 3 is switched from the reverse direction to the positive direction. This electrical angle coincides with the electrical angle at the intersection of the torque curve AB- and the torque curve AB + in FIG.

  FIG. 5D ′ shows a state in which the magnet rotor 1 is rotated by 270 ° in electrical angle and the energizing direction of the exciting coil 3 is switched. A forward current flows through the exciting coil 3 and the B-phase yoke 5 is magnetized to the N pole, and a reverse current flows through the exciting coil 4 and the A-phase yoke 7 is magnetized to the S pole. At this time, clockwise torque corresponding to the torque curve AB in FIG. 4A acts, and the magnet rotor 1 rotates in response to the rotational force in the θ direction.

  By repeating the above operation, the magnet rotor 1 can be continuously rotated. Note that reverse rotation is also possible by reversing the sign of the binarized signal A or the binarized signal B.

  In the feedback energization switching mode, the magnet rotor 1 can be rotated by a desired angle by inputting the number of drive pulses and the rotation direction. Further, by controlling the current flowing through the exciting coils 3 and 4, the magnetic rotor 1 is rotated at a desired speed by changing the magnetic force between the magnetic pole teeth of the yokes 5 and 7 and the magnetic pole of the magnet rotor 1. Can do.

  In the feedback energization switching mode, energization is switched at an electrical angle that coincides with the intersection of each torque curve, so that the torque obtained from the motor can be maximized (torque curve T in FIG. 4A). Further, in the feedback energization switching mode, the energization is switched while detecting the position of the magnet rotor 1, so that the step-out does not occur unlike the non-feedback energization switching mode, and it can be driven at high speed and high efficiency. Become.

  As described above, in the present embodiment, a plurality of magnetic shaft members 14 are arranged on the B-phase lid member 12 at substantially equal intervals in the circumferential direction, and one end of the plurality of magnetic shaft members 14 is connected to the magnet rotor 1. The other end is exposed to the outside of the B-phase lid member 12 so as to face the end surface 1a. And the magnetic detection element 15 and the magnetic detection element 17 are arrange | positioned at the end surface of the side exposed to the exterior of the B phase cover member 12 of some magnetic shaft members 14a and 14b among the some magnetic members 14, respectively. .

  As a result, it is not necessary to dispose a detection rotor different from the magnet rotor 1 on the motor shaft as in the prior art. As a result, the stepping motor can be reduced in size and cost.

  Further, by arranging the end surfaces of the magnetic shaft members 14a and 14b facing the magnet rotor 1 close to the end surface 1a of the magnet rotor 1, the magnetic pole position of the magnet rotor 1 can be easily detected even with a claw pole type stepping motor. Accuracy can be increased.

  The configuration of the present invention is not limited to that exemplified in the above embodiment, and the material, shape, dimensions, form, number, arrangement location, and the like can be changed as appropriate without departing from the scope of the present invention. It is.

  For example, as shown in FIG. 6, a back yoke 18 made of a magnetic material may be disposed on the opposite surface of the magnetic shaft member 14 of the magnetic detection element 15.

  In this way, the permeance of the magnetic detection circuit is improved by the action of the back yoke 18, and the magnetic pole position of the magnet rotor 1 can be detected with higher accuracy.

DESCRIPTION OF SYMBOLS 1 Magnet rotor 3, 4 Excitation coil 5, 6, 7, 8 Yoke 14 Magnetic shaft member 15, 17 Magnetic detection element 18 Back yoke

Claims (5)

A rotor having a plurality of magnetic poles formed in a circumferential direction;
Formed of a non-magnetic material, and a lid member for covering the axial end face of the front SL rotor,
A magnetic sensing element;
One end faces the axial end face of the rotor, so that the other end portion in the magnetic detection element is arranged, and a magnetic property shaft member supported on said lid member,
A plurality of the magnetic shaft members are arranged at equal intervals in the circumferential direction around the rotor shaft,
Among the plurality of magnetic shaft member, a motor, wherein that you have the magnetic detection element to the other end of the part of the magnetic shaft member is disposed. The rotor has a rotor shaft;
Attached to said cover member, a motor according to claim 1, characterized that you have a support member for rotatably supporting the rotor shaft. It said magnetic axis member, the motor according to claim 1 or 2, characterized in Tei Rukoto respectively arranged to face the matched positions the boundary position or peak position location of magnetic poles formed on the rotor.   4. The motor according to claim 1, wherein a back yoke made of a magnetic material is disposed on a surface opposite to the magnetic shaft member of the magnetic detection element. 5.   5. The motor according to claim 1, wherein the number of the magnetic shaft members is an integral multiple of the number of magnetic poles of the rotor.

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