JP4197258B2 - Stepper motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a claw pole type stepper motor used for OA equipment, computer peripheral equipment, industrial equipment, amusement equipment, and the like, and more specifically, a simple modification is made to a pole tooth constituting a comb-like magnetic pole. Thus, the present invention relates to a stepper motor that realizes a configuration in which noise is hardly applied to the magnetic pole sensor.
[0002]
[Prior art]
The stepper motor is an electric motor that is driven to rotate in proportion to the number of input pulses, and a low-cost system based on open loop control can be constructed. As shown in FIG. 1, the conventional claw-pole type stepper motor includes an A-phase stator 11, a B-phase stator 12, and a permanent magnet rotor R that are configured in two stages.
[0003]
The A-phase stator 11 includes a comb-shaped magnetic pole MT and a coil (A-phase coil) C that are attached to the A-phase yoke 11a, and the comb-shaped magnetic pole MT is disposed in a direction in which the rows of pole teeth face each other. Has been configured. Similarly, the B-phase stator 12 includes a comb-shaped magnetic pole MT and a coil (B-phase coil) C attached to the B-phase yoke 12a. The comb-shaped magnetic pole MT also meshes with a row of pole teeth facing each other. It is arranged in the direction. In the stepper motor 1 of FIG. 1, all the pole teeth have the same shape.
[0004]
Further, although not shown, the permanent magnet rotor R is multipolarized with N poles and S poles (rotor magnetic poles RM) alternately in the circumferential direction. The stepper motor 1 generates a force between the pole teeth excited by the A-phase and B-phase coils C and the rotor magnetic poles formed on the permanent magnet rotor R. The permanent magnet rotor R is rotated by sequentially switching the energization of the A phase and the B phase to generate torque.
[0005]
By the way, with the improvement in the performance of the equipment itself on which the stepper motor is mounted, high angular accuracy is required. As shown in FIGS. 2 (a) and 2 (b), the stepper on which the encoder is mounted is provided. Motors are also being used.
[0006]
In the encoder 21 of FIG. 2A, a rotating magnetic pole plate 21a in which a permanent magnet having NS poles in the axial direction is formed, and a magnetic sensor MS is attached to the plate surface side near the outer periphery of the rotating magnetic pole plate 21a. It consists of a sensor substrate 21b. Also. The encoder 22 in FIG. 2B is a sensor substrate in which a rotating magnetic pole plate 22a in which a permanent magnet having NS poles in the circumferential direction is formed, and a magnetic sensor MS is attached to the outer peripheral end face side of the rotating magnetic pole plate 22a. 22b.
[0007]
In the encoders of FIGS. 2A and 2B, the rotating magnetic pole plates 21a and 22a are used, so that the size of the motor increases and the manufacturing cost also increases. From this, a magnetic pole position detection technique as shown in Patent Document 1 is also known.
[0008]
[Patent Document 1]
JP-A-2001-078392
[0009]
[Problems to be solved by the invention]
In this magnetic pole position detection technique, as shown in FIG. 3, the magnetic sensor MS is provided on the B-phase stator 12 side, and detects the leakage magnetic flux of the magnetic pole magnetized on the permanent magnet rotor. However, the magnetic sensor MS of FIG. 3 is affected by the magnetic flux passing through the pole teeth MT, which results in detection noise and causes malfunction. Moreover, in order to reduce the influence of this noise, highly accurate positioning is required when the sensor is attached.
[0010]
The present invention has been made in view of the above-described background, and an object of the present invention is to provide a stepper motor including a magnetic sensor for detecting a leakage magnetic flux of a rotor magnet. It is an object of the present invention to provide a stepper motor that is not subject to this and does not require positioning accuracy of a magnetic sensor.
[0011]
[Means for Solving the Problems]
The stepper motor of the present invention has a stator in which two or more pairs of yokes and coils each formed with opposed comb-shaped magnetic poles are stacked, and is opposed to the pole-tooth surface of the comb-shaped magnetic poles. In addition, a claw pole type including a permanent magnet rotor in which N pole and S pole rotor magnetic poles are alternately magnetized and a magnetic sensor for detecting the position of the rotor magnetic pole is assumed.
Under this premise, in order to make the passing magnetic flux of the predetermined pole tooth close to the magnetic sensor among the pole teeth constituting the comb-shaped magnetic pole smaller than the passing magnetic flux of the other pole teeth , Various structures shown below were adopted.
First, among the pole teeth constituting the comb-shaped magnetic pole, a gap between a predetermined pole tooth located near the magnetic sensor and the permanent magnet rotor is larger than a gap between other pole teeth and the permanent magnet rotor. It can be formed to be large.
Moreover, you may comprise so that the magnitude | size of the predetermined pole tooth located in the vicinity of the said magnetic sensor may be smaller than the magnitude | size of another pole tooth among the pole teeth which comprise the said comb-tooth shaped magnetic pole.
Furthermore, among the pole teeth constituting the comb-shaped magnetic pole, a predetermined pole tooth located in the vicinity of the magnetic sensor may be removed from the yoke.
[0012]
According to the present invention, the magnetic flux passing through the predetermined pole tooth, a that less than the magnetic flux passing through the other pole teeth. Hereinafter, the pole teeth configured such that the passing magnetic flux is smaller than the passing fluxes of the other pole teeth are referred to as “small flux pole teeth”.
[0013]
In the present invention, the number of stages of the stator can be three or more, but usually it is two. In the present invention, the number of the magnetic sensors as described above is usually two, period of the magnetic sensors Ru can be an electrical angle of for example 90 °.
[0015]
In the present invention, the detent torque can be reduced by using the predetermined pole teeth formed on the comb-shaped magnetic poles as small magnetic flux pole teeth. The number of small magnetic flux pole teeth of the stator on the side where no magnetic sensor is provided is preferably the same as the number of small magnetic flux pole teeth of the stator on the side where no magnetic sensor is provided.
[0016]
Further, in the stepper motor of the present invention, since the number of pole teeth for reducing the magnetic flux is small (usually the same as the number of magnetic sensors) for one stator, the torque is reduced only slightly in the low speed region. The torque in the high speed region is equal to or higher than that of a normal stepper motor.
[0017]
In the present invention, in the above stepper motor in which the sensor substrate is attached to one end surface of the yoke with screws or bolts, the screw holes or bolt holes provided in the sensor substrate are arc-shaped (provided that The center of the arc-shaped hole can be formed to be equal to the center axis of the sensor substrate. Thereby, the advance angle control by adjusting the mounting angle of the magnetic sensor becomes possible.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
4 to 5 are explanatory views showing a first embodiment of a stepper motor according to the present invention. Specifically, FIG. 4A is an explanatory diagram viewed from the B phase side of the stepper motor 31, and FIG. 4B is a side view of the stepper motor 31. 5A is a cutaway explanatory view showing the inside of the stepper motor 31, and FIG. 5B is a partial explanatory view showing the inside of the stepper motor 31.
[0019]
The stator of the stepper motor 31 includes an A-phase stator 31a and a B-phase stator 31b. The A-phase stator 31a includes a set of an A-phase yoke and a coil C. The B-phase stator 31b includes a B-phase yoke and a coil C. It consists of a pair. Comb-like magnetic poles arranged opposite to each other are formed on the A-phase yoke and the B-phase yoke, respectively, and N-pole and S-pole rotor magnetic poles RM are alternately attached in multiple poles so as to face the pole tooth surfaces of the comb-like magnetic poles. A magnetized permanent magnet rotor R is provided.
[0020]
An encoder 40 that detects the position of the rotor magnetic pole RM is provided on the end surface of the B-phase stator 31b opposite to the A-phase stator 31a side. The encoder 40 includes a sensor substrate 41 to which a magnetic sensor MS is attached. The sensor board 41 is provided with two bolt holes BLTH, and is attached to two screw grooves BLTS formed in the B-phase stator 31b by bolts BLT.
[0021]
The comb-like magnetic poles of the A-phase yoke and the B-phase yoke have pole teeth that face each other. Of the pole teeth of the B-phase yoke, the pole tooth (MT1 ') located in the vicinity of the magnetic sensor MS has a gap between the permanent magnet rotor R and the gap between the other pole teeth (MT1, MT2) and the permanent magnet rotor R. It is formed so as to be larger. Although not shown in FIGS. 4 (a) and 4 (b) and FIGS. 5 (a) and 5 (b), the magnetic poles of the B-phase yoke are similar to the magnetic poles of the A-phase yoke. The gap with the permanent magnet rotor R is formed to be larger than the gap between the other pole teeth and the permanent magnet rotor R. Thereby, the rotation balance of the rotor is achieved.
[0022]
In the first embodiment, the magnetic sensor MS is not affected or reduced by the influence of leakage magnetic flux from nearby pole teeth. Therefore, no noise is applied to the magnetic sensor MS, and therefore no malfunction of the motor occurs.
[0023]
6 to 8 are explanatory views showing a second embodiment of the stepper motor of the present invention. FIG. 6A is an explanatory view seen from the B-phase side of the stepper motor 32, and FIG. 6B shows a side view of the stepper motor 32. FIG. 7 is a notch explanatory view showing the inside of the stepper motor 32. FIGS. 8A and 8B are partial explanatory views showing the inside of the stepper motor 32.
[0024]
The stator of the stepper motor 32 includes an A-phase stator 32a and a B-phase stator 32b. The A-phase stator 32a includes a combination of an A-phase yoke and a coil C. The B-phase stator 32b includes a B-phase yoke and a coil C. It consists of a pair. The A-phase yoke and the B-phase yoke have comb-shaped magnetic poles arranged opposite to each other, and the N-pole and S-pole rotor magnetic poles RM are alternately arranged in multiple poles so as to face the pole-tooth surfaces of the comb-shaped magnetic poles. A magnetized permanent magnet rotor R is provided.
[0025]
An encoder 40 that detects the position of the rotor magnetic pole RM is provided on the end surface of the B-phase stator 32b opposite to the A-phase stator 32a side. The encoder 40 includes a sensor substrate 41 to which a magnetic sensor MS is attached. The sensor board 41 is provided with two bolt holes BLTH, and is attached to two screw grooves BLTS formed in the B-phase stator 31b by bolts BLT.
[0026]
In the stepper motor 32 of this embodiment, as shown in FIGS. 6A and 8A, one of the two magnetic sensors MS is located immediately above the pole tooth position, and the magnetic tooth The magnetic teeth at the position have been removed. Further, as shown in FIGS. 6A and 8B, the other of the two magnetic sensors MS is located between the two magnetic teeth, and one of the two magnetic teeth is removed. At the same time, the other has a smaller pole tooth size. FIG. 7 shows a portion where the pole teeth are removed.
[0027]
6 (a), 7 and 8 (a), (b), the removed magnetic tooth portion is indicated by E, and in FIGS. 6 (a), 8 (b), the size is small. The magnetic tooth is indicated by MT2 '. In each figure, normal magnetic teeth are indicated by MT1 and MT2.
[0028]
In the present embodiment, even if one or both of the two sensor positions MS straddle two pole tooth positions, the magnetic sensor MS is affected by leakage magnetic flux from nearby pole teeth. Is eliminated or reduced, noise is not applied to the magnetic sensor MS, and therefore, the motor does not malfunction. Since other configurations and operational effects are the same as those in the first embodiment, detailed description thereof is omitted.
[0029]
FIG. 9 is an explanatory diagram of a sensor substrate 41 that can be used in the first embodiment and the second embodiment. The sensor substrate 41 is attached to one end face of the B-phase yoke by a bolt BLT, and the bolt hole BLTH is formed in an arc shape within a range of a ½ step length centering on the central axis of the sensor substrate 41. Has been. The advance angle control can be performed by adjusting the mounting angle of the magnetic sensor MS to the B-phase stator 31b or 32b. When the advance angle control is performed, the torque and the rotation speed vary greatly depending on the rotation direction. For example, if the advance angle control during the forward rotation, the speed can be increased during the forward rotation, and the rotation is slow during the reverse rotation of the return. It can be applied to applications where there is no problem in control.
[0030]
Further, when the sensor substrate 41 is mounted, there may be individual variations, but when the speed control is performed, good control can be performed to such an extent that a slight difference occurs in the drive current. Furthermore, although there is a limit depending on how it is used, even if the time is rough, for example, it is suitable for use as a power motor that can achieve the object if the motor performs a simple reciprocating motion.
[0031]
【The invention's effect】
In the present invention, the magnetic sensor is not affected by noise from the pole teeth, thereby providing a stepper motor that does not require the positioning accuracy of the magnetic sensor. In addition, the detent torque can be reduced as a result of the pole teeth being the predetermined pole teeth as the small magnetic flux pole teeth, thereby reducing vibration and noise caused by the detent torque. Furthermore, basically, since only a few pole teeth are processed per phase, manufacturing is facilitated without a large-scale change of the yoke forming mold.
[0032]
In the present invention, when the sensor substrate is attached to one end surface of the yoke by screws or bolts, the screw holes or bolt holes provided in the sensor substrate are arc-shaped with a predetermined length (however, the center of the hole on the arc is In this case, the lead angle can be controlled by adjusting the mounting angle of the magnetic sensor.
[Brief description of the drawings]
FIG. 1 is an external view showing a conventional stepper motor.
FIG. 2A shows a rotating magnetic pole plate in which a permanent magnet having NS poles in the axial direction is formed, and a sensor substrate on which a magnetic sensor MS is attached on the plate surface side close to the outer periphery of the rotating magnetic pole plate. It is a figure which shows the conventional stepper motor by which the encoder which consists of is mounted.
(B) is a conventional stepper motor comprising a rotating magnetic pole plate in which a permanent magnet having NS poles in the circumferential direction is formed, and a sensor substrate to which a magnetic sensor MS is attached on the outer peripheral end face side of the rotating magnetic pole plate. FIG.
FIG. 3 is an explanatory diagram of a conventional stepper motor equipped with a magnetic sensor that detects a leakage magnetic flux of a magnetic pole magnetized on a permanent magnet rotor.
FIG. 4A is a diagram of the stepper motor according to the first embodiment of the present invention viewed from the B-phase side.
(B) is the side view.
FIG. 5A is a cutaway view showing the inside of the stepper motor according to the first embodiment of the present invention.
(B) is a partial explanatory view showing the inside.
FIG. 6A is an explanatory diagram viewed from the B-phase side of the stepper motor according to the second embodiment of the present invention.
(B) is the side view.
FIG. 7 is a cutaway explanatory view showing the inside of a stepper motor according to a second embodiment of the present invention.
FIG. 8 is a partial explanatory view showing the inside of an explanatory view of a stepper motor according to a second embodiment of the present invention.
FIG. 9 is an explanatory diagram of a sensor substrate that can be used in the first embodiment and the second embodiment.
[Explanation of symbols]
31, 32 Stepper motor 40 Encoder 41 Sensor board 31a, 32a A phase stator 31b, 32b B phase stator BLT Bolt BLTH Bolt hole BLTS Screw groove C Coil MS Magnetic sensors MT1, MT2, MT1 ', MT2' Polar teeth R Permanent magnet rotor RM rotor magnetic pole

Claims (4)

A stator formed by stacking two or more pairs of yokes and coils each formed with opposing comb-shaped magnetic poles;
A permanent magnet rotor in which N-pole and S-pole rotor magnetic poles are alternately magnetized so as to be opposed to the pole tooth surfaces of the comb-shaped magnetic poles;
In a claw pole type stepper motor provided with a magnetic sensor for detecting the position of the rotor magnetic pole,
Among the pole teeth constituting the comb-shaped magnetic poles, the gap between the predetermined pole teeth located near the magnetic sensor and the permanent magnet rotor is larger than the gap between the other pole teeth and the permanent magnet rotor. this, features and be away Teppamota formed to. A stator formed by stacking two or more pairs of yokes and coils each formed with opposing comb-shaped magnetic poles;
A permanent magnet rotor in which N-pole and S-pole rotor magnetic poles are alternately magnetized so as to be opposed to the pole tooth surfaces of the comb-shaped magnetic poles;
In a claw pole type stepper motor provided with a magnetic sensor for detecting the position of the rotor magnetic pole,
The comb of the pole teeth constituting the teeth-shaped magnetic poles, the magnitude of the predetermined pole tooth positioned near the magnetic sensor, features and be away Teppamota is smaller than the size of the other pole teeth. A stator formed by stacking two or more pairs of yokes and coils each formed with opposing comb-shaped magnetic poles;
A permanent magnet rotor in which N-pole and S-pole rotor magnetic poles are alternately magnetized so as to be opposed to the pole tooth surfaces of the comb-shaped magnetic poles;
In a claw pole type stepper motor provided with a magnetic sensor for detecting the position of the rotor magnetic pole,
The comb of the pole teeth constituting the teeth-shaped magnetic poles, the features and to Luz Teppamota that a predetermined pole tooth located in the vicinity of the magnetic sensor is removed from said yoke. In a stepper motor in which a sensor substrate including a magnetic sensor is attached to one end face of the yoke with a screw or a bolt,
2. The screw hole or bolt hole provided in the sensor substrate is formed in an arc shape within a range of 1/2 step length centering on the central axis of the sensor substrate. 4. The stepper motor according to any one of 3.

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