JP2021122171A - Stepping motor - Google Patents

Abstract

To provide a stepping motor capable of simultaneously grinding outer peripheral surfaces of a rotor core and a sensor rotor.SOLUTION: The present invention relates to a stepping motor comprising a stator 130 and a rotor 140 in a front flange 110 and a rear flange 120 and comprising a sensor cover 210 including a rotation angle sensor which detects a rotation angle of the rotor 140, in the rear flange 120. The rotation angle sensor includes a sensor stator 230, and a sensor rotor 220 which is disposed inside of the sensor stator 230, and the rotor 140 includes a rotary shaft 142 and a rotor core 141 which is fixed to the rotary shaft 142. A first bearing 112 supporting the rotary shaft 142 is disposed in the front flange 110, a second bearing 213 supporting the rotary shaft 142 and the sensor stator 230 are provided in the sensor cover 210. The sensor rotor 220 is fixed to the rotary shaft 142 between the rotor core 141 and the second bearing 213.SELECTED DRAWING: Figure 2

Description

The present invention relates to a stepping motor, and more particularly to a stepping motor provided with a rotation angle sensor that detects the position and speed of the rotor of the stepping motor.

Conventionally, a stepping motor including a sensor for detecting the position and speed of a rotor has been proposed (see, for example, Patent Document 1). FIG. 6 is a stepping motor disclosed in Patent Document 1, and is a diagram showing a configuration of a two-phase hybrid type stepping motor. In FIG. 6, the stepping motor 1 includes a stator 2 and a rotor 3 rotatably arranged on an axial center in the stator 2. The stator 2 has a plurality of magnetic poles radially arranged inward on the stator core 4, and a plurality of stator pole teeth in the circumferential direction on the inner peripheral surface of each magnetic pole. 4a are formed at equal pitches. Then, in order to form a rotating magnetic field, the stator 2 has a winding 5 wound around each magnetic pole of the stator core 4, surrounds the winding 5, and is inside the stator core 4. The motor frames 10 and 11 fitted to the peripheral surface are fastened and supported by screws or the like (not shown). The stepping motor 1 includes a stator 2 and a rotor 3 rotatably arranged on an axial center in the stator 2. A plurality of magnetic poles extending radially inward are arranged on the stator core 4 of the stator 2, and a plurality of stator pole teeth 4a are arranged in the circumferential direction on the inner peripheral surface of each magnetic pole. It is formed at an equal pitch. Then, in order to form a rotating magnetic field, the stator 2 has a winding 5 wound around each magnetic pole of the stator core 4, surrounds the winding 5, and fits into the inner peripheral surface of the stator core 4. The matching motor frames 10 and 11 are fastened and supported by screws or the like (not shown).

The rotor 3 includes rotor cores 6a and 6b, and is rotatably supported by a bearing 9. A space 22 is formed in the right outer frame 11 of the bearing 9 by a step portion 11a whose diameter is gradually reduced toward the bearing 9, and the space 22 corresponds to an end surface of the winding 5 of the stator 2. Has been formed by. A sensor 23 for detecting the position or rotation speed of the rotor 3 is arranged in the space 22.

The sensor 23 is a variable reluctance type resolver, and includes a fixing portion 23a and a rotating portion 23b. The fixing portion 23a is fixed to the inner peripheral surface of the step portion 11a of the frame 11, and the rotating portion 23b is fixed to the end portion 7a of the rotating shaft 7 so as to interact with the fixing portion 23a without contact. .. The fixed portion 23a is provided with a printed circuit board 24 on which an electronic circuit connected to the sensor 23 is formed.

In the stepping motor having the above configuration, the fixing portion 23a and the rotating portion 23b constituting the sensor 23 are housed in the space 22 formed up to the portion corresponding to the end surface of the winding 5 of the stator 2. The total length can be almost the same as the total length of the motor without incorporating.

Japanese Unexamined Patent Publication No. 11-55902

In the hybrid type stepping motor of Patent Document 1, a bearing 9 that rotatably supports the rotor 3 is arranged between the rotor core (corresponding to the rotor core) 6b of the rotor 3 and the rotating portion 23b of the sensor 23. Therefore, after the rotor 3 is assembled to the bearing 9, the rotating portion 23b of the sensor 23 is fixed to the end portion 7a of the rotating shaft 7. Therefore, the outer peripheral surfaces of the rotor core 6b and the rotating portion 23b of the sensor 23 cannot be ground at the same time, and the concentric accuracy of the rotating shaft 7 and the rotating portion 23b of the sensor 23 cannot be improved. As a result, there is a problem that the accuracy of the gap (air gap) between the fixed portion 23a and the rotating portion 23b of the sensor 23 cannot be improved, and the detection accuracy cannot be improved.

Therefore, an object of the present invention is to provide a stepping motor capable of simultaneously grinding the outer peripheral surface of the rotor core and the rotating portion of the sensor and increasing the concentric accuracy of the shaft and the rotating portion of the sensor. There is.

The present invention is a stepping motor provided on a frame with a stator, a rotor rotatably arranged inside the stator, and a sensor cover having a rotation angle sensor for detecting the rotation angle of the rotor. The rotor includes a rotation shaft and a rotor core fixed to the rotation shaft, and has a sensor stator and a sensor rotor rotatably arranged inside the sensor stator. A first bearing that rotatably supports the rotating shaft is arranged, the sensor cover is provided with a second bearing that rotatably supports the rotating shaft and a sensor stator, and the sensor rotor is a rotor core and a second. It is a stepping motor fixed to the rotating shaft between the bearing and the rotating shaft.

In the present invention, since the sensor rotor is fixed to the rotating shaft between the rotor core and the second bearing, the outer peripheral surface of the rotor core and the sensor rotor with the rotor core and the sensor rotor fixed to the rotating shaft. The rotating shaft can be inserted into the second bearing after simultaneously grinding. Therefore, the accuracy of the gap between the sensor stator of the rotation angle sensor and the sensor rotor can be improved, and the detection accuracy of the rotation angle sensor can be improved.

Here, the sensor cover is provided with a cylindrical boss portion that protrudes in the axial direction, a second bearing is fixed to the inner peripheral surface of the boss portion, and a sensor stator is fixed to the outer peripheral surface of the boss portion. Is a preferred embodiment. In such an embodiment, the rotation shaft → the second bearing → the boss portion → the sensor stator are aligned in this order to improve the concentricity accuracy between the rotation center of the rotation shaft (sensor rotor) and the center of the sensor stator. Can be done.

The present invention is suitable when applied to a hybrid type stepping motor.

According to the present invention, the accuracy of the gap between the sensor stator of the rotation angle sensor and the sensor rotor can be increased, and the detection accuracy of the rotation angle sensor can be increased.

It is sectional drawing which shows the stepping motor of embodiment of this invention. FIG. 1 is a cross-sectional view showing a state in which the sensor portion is separated from the motor main body portion. It is an arrow III direction arrow view of FIG. 2 (A). It is sectional drawing which excluded the bearing from FIG. 2 (B). It is a V-direction arrow view of FIG. 2 (B). It is sectional drawing which shows the conventional stepping motor.

The stepping motor according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5. The stepping motor shown in FIG. 1 is a two-phase hybrid type stepping motor of an inner rotor, and is composed of a motor unit 100 and a sensor unit 200. Hereinafter, the configurations of the motor unit 100 and the sensor unit 200 will be described in order.

(1) Configuration of Motor Unit In FIG. 1, reference numeral 110 is a front flange (frame). The front flange 110 is made of, for example, an aluminum alloy and has a square shape when viewed from the front. A cylindrical boss portion 111 projecting in the axial direction is formed in the central portion of the back surface of the front flange 110, and the first bearing 112 is fixed to the inner peripheral surface of the boss portion 111. The inner peripheral surface and the outer peripheral surface of the boss portion 111 are processed so as to have high concentric accuracy by lathe processing.

The rear flange (frame) 120 is arranged at a position separated from the front flange 110 in the axial direction. The rear flange 120 is made of, for example, an aluminum alloy and has a square shape when viewed from the back surface. A cylindrical boss portion 121 projecting in the axial direction is formed in the central portion of the rear flange 120, and a space 123 is formed in the center of the boss portion 121. A stator 130 is sandwiched between the front flange 110 and the rear flange 120.

FIG. 3 is a view of FIG. 2A viewed from the direction of arrow III. As shown in FIG. 3, through holes 125 for inserting fasteners such as screws are formed at the four corners of the rear flange 120. The fastener material inserted into the sensor cover 210, which will be described later, is passed through the through hole 125 and the stator core 131 and screwed into the screw hole formed in the front flange 110, whereby the front flange 110, the stator core 131, the rear flange 120, and the rear flange 120 are screwed. The sensor covers 210 are coupled to each other.

The stator 130 includes a stator core 131. The stator core 131 is formed by laminating a predetermined number of cores made of a soft magnetic material (for example, an electromagnetic steel plate) in the axial direction. The stator core 131 has a quadrangular shape, and a plurality of (for example, eight) stator poles are radially radially spaced at equal intervals in the circumferential direction, and a plurality of stator poles (for example, eight) are projected inward at equal pitches at the tips of the respective stator poles. It has small teeth (not shown). A coil 133 is wound around the stator core 131 via an insulator 132. The coil 133 is composed of an A-phase coil and a B-phase coil, and constitutes a stator 130 of a two-phase hybrid type stepping motor.

A rotor 140 is rotatably arranged inside the stator 130. The rotor 140 includes a rotor core 141, a rotating shaft 142 fixed to the center of the rotor core 141, and a magnet (permanent magnet) 143. The rotor core 141 has a substantially circular shape, and has a plurality of small teeth (not shown) on the outer peripheral surface thereof at equal pitches in the circumferential direction. The small teeth and the small teeth formed at the tip of the stator pole of the stator core 131 are arranged to face each other with a predetermined air gap. One end side of the rotating shaft 142 is rotatably supported by a first bearing 112.

The magnet 143 has a ring shape, and two poles (N pole and S pole) are magnetized in the axial direction. Two rotor cores 141 are arranged with a magnet 143 in between, one of which generates an N-pole magnetic field toward the outer periphery and the other of which generates an S-pole magnetic field. The rotor core 141 is configured by laminating a predetermined number of cores made of a soft magnetic material (for example, an electromagnetic steel plate) in the axial direction.

As shown in FIGS. 1 and 2, a notch is formed in a part of the outer peripheral wall of the rear flange 120, and a receptacle 150 projecting outward is attached to the notch. The coil 133 (A-phase coil and B-phase coil) wound around the stator core 131 is connected to a wiring pattern formed on the circuit board 151 arranged at the end of the insulator 132, and the terminal pin 152 is included in the wiring pattern. It is connected. In this way, the terminal pin 152 and the coil 133 are electrically conductive via the wiring pattern. A rectangular opening is formed by the receptacle 150 and the circuit board 152, and a plug connected to an external power source is inserted into the opening to supply a current to the coil 133.

(2) Configuration of Sensor Unit Next, the configuration of the sensor unit 200 will be described. In FIGS. 1 and 2, reference numeral 210 is a sensor cover. The sensor cover 210 is made of, for example, an aluminum alloy and has a square shape when viewed from the back side. An annular recess 211 is formed in the sensor cover 210, and an annular protrusion 122 formed in the rear flange 120 is fitted in the annular recess 211. A cylindrical boss portion 212 protruding in the axial direction is formed in the center of the bottom of the annular recess 211, and a second bearing 213 is fixed to the inner peripheral surface of the boss portion 212. The other end side of the rotating shaft 142 is rotatably supported by the second bearing 213. As a result, the rotor 140 is rotatably supported by the first bearing 112 and the second bearing 213. The inner peripheral surface and the outer peripheral surface of the boss portion 212 are processed so as to have high concentric accuracy by lathe processing.

FIG. 5 is a back view of the sensor cover 210. As shown in FIG. 5, counterbore holes 214 are formed at the four corners of the sensor cover 210. As described above, the fastening material is inserted from the counterbore hole 214 to connect the sensor cover 210 to the front flange 110.

A sensor rotor 220 is fixed to a rotating shaft 142 inside the second bearing 213. The sensor rotor 220 has a circular shape whose outer diameter is smaller than the inner diameter of the space 123 of the rear flange 120, and a plurality of small teeth 221 (see FIG. 3, FIG. 3 shows only a part). The sensor rotor 220 is configured by laminating a predetermined number of cores made of a soft magnetic material (for example, an electromagnetic steel plate) made of the same material as the rotor core 141 in the axial direction. A hollow cylindrical sleeve 124 made of a non-magnetic material (for example, an aluminum alloy) is interposed between the rotor core 141 and the sensor rotor 220.

A sensor stator 230 is fixed to the outer peripheral surface of the boss portion 212 of the sensor cover 210. The sensor stator 230 is configured by laminating a predetermined number of cores made of a soft magnetic material (for example, an electromagnetic steel plate) in the axial direction. In the sensor stator 230, as shown in FIG. 4, a plurality of teeth 231 extend inward in diameter from the annulus portion. The teeth 231 have the same shape and are arranged at equal intervals in the circumferential direction. A plurality of small teeth 232 are formed at the tip of the teeth 231. A detection winding 233 is wound around the teeth 231 via an insulator 232.

As shown in FIGS. 1 and 2, a notch is formed in a part of the outer peripheral wall of the sensor cover 210, and a receptacle 250 projecting outward is attached to the notch. The detection winding 233 wound around the sensor stator 230 is connected to a wiring pattern formed on the circuit board 251 arranged at the end of the insulator 232, and the terminal pin 252 is connected to the wiring pattern. In this way, the terminal pin 252 and the detection winding 233 are electrically conductive via the wiring pattern. A rectangular opening is formed by the receptacle 250 and the circuit board 252, a plug connected to the external control device is inserted into the opening, and a signal output from the detection winding 233 is sent to the external control device.

(3) Manufacturing Method of Stepping Motor Next, a manufacturing method of the stepping motor having the above configuration will be described.
1. 1. Manufacture of a stator The stator 130 includes a stator core 131, a coil 133 (A-phase coil and a B-phase coil) wound around a stator pole of the stator core 131 via an insulator 132, and a circuit board 150 arranged on the lower end surface of the insulator 132. And have.

In order to manufacture such a stator 130, first, the inner peripheral surface (the surface facing the rotor core 141) of the tip of the stator pole of the stator core 131 formed by laminating a predetermined number of cores in the axial direction is ground. Next, insulators 132 are mounted from both sides of the stator core 130 in the axial direction, and coils 133 (A-phase coil and B-phase coil) are wound around each stator pole. Next, the terminal of the coil 133 is connected to the wiring pattern formed on the circuit board 151 arranged on the lower end surface of the insulator 132.

2. Manufacture of Rotor and Sensor Rotor The rotor 140 includes a rotor core 141, a magnet (permanent magnet) 143 arranged between the rotor cores 141, and a rotating shaft 142. In order to manufacture such a rotor 140, first, the rotating shaft 142 is inserted into the through hole formed in the center of the rotor core 141 and the magnet 143, the rotating shaft 142 is inserted into the sleeve 124, and the center of the sensor rotor 220 is inserted. After inserting the rotating shaft 142 into the through hole formed in the above, an adhesive is applied to bond the rotor core 141 and the sensor rotor 220 to a predetermined position. Next, both ends of the rotating shaft 142 are supported, and the outer peripheral surfaces of the rotor core 141 and the sensor rotor 220 are ground to concentric with the outer peripheral surface of the rotor core 141, the outer peripheral surface of the sensor rotor 220, and the rotating shaft 142. Get accuracy.

3. 3. Fabrication of Internal Configuration of Sensor Cover First, a predetermined number of cores constituting the sensor stator 230 are laminated in the axial direction, and the inner peripheral surface (the surface facing the sensor rotor 220) at the tip of the teeth 231 is ground. Next, insulators 232 are mounted from both sides in the axial direction of the stacked cores, and the detection winding 233 is wound around each tooth 231 via the insulator 232. Next, the terminal of the detection winding 233 is connected to the wiring pattern formed on the circuit board 251 arranged at the lower end of the insulator 232. Next, the outer peripheral surface of the boss portion 212 to which the second bearing 213 of the sensor cover 210 is fixed is fitted to the inner peripheral surface of the teeth 231 of the sensor stator 230 (the surface facing the sensor rotor 220). The sensor stator 230 is attached to the sensor cover 210.

4. Manufacture of motor part The outer peripheral surface of the boss part 111 of the front flange 110 to which the first bearing 112 is mounted is the inner peripheral surface of the stator pole (the surface facing the rotor core 141) from one end side of the stator core 131 around which the coil 133 is wound. The end surface of the outer peripheral wall of the front flange 110 is brought into contact with the end surface of the stator core 131 to be coupled.

Next, one end of the rotating shaft 142 of the rotor 140 is inserted into the inner ring of the first bearing 112 mounted on the front flange 110, and the rotor 140 is housed in the stator 130. Next, the outer peripheral surface of the boss portion 121 of the rear flange 120 is fitted to the inner peripheral surface of the stator pole (the surface facing the rotor core 141) from the other end side of the stator core 131 around which the coil 133 is wound, and the rear flange 120 The outer peripheral wall of the stator core 131 is brought into contact with the end face of the stator core 131 to be connected. In this state, the sensor rotor 220 mounted on the rotating shaft 142 is arranged outside the rear flange 120 (see FIG. 2A).

5. Attachment of the sensor cover to the motor unit When the sensor cover 210 is attached to the rear flange 120, an annular protrusion formed on the end face of the rear flange 120 is formed in an annular recess 211 formed inside the outer wall portion 210a of the sensor cover 210. The portion 122 is fitted, and the end surface of the outer wall portion 210a of the sensor cover 210 is brought into contact with the rear flange 120. As a result, the other end side of the rotating shaft 142 is inserted into the inner ring of the second bearing 213. Then, a fastening material such as a screw is inserted through the counterbore hole 214 into the sensor cover 210, the rear flange 120, and the stator core 131, and screwed into the screw hole formed in the front flange 110 for fastening.

As described above, in the stepping motor having the above configuration, since the sensor rotor 220 is fixed to the rotating shaft 142 between the rotor core 141 and the second bearing 213, the rotor core 141 and the sensor rotor are fixed to the rotating shaft 142. After simultaneously grinding the outer peripheral surfaces of the rotor core 141 and the sensor rotor 220 with the 220 fixed, the rotating shaft 142 can be inserted into the second second bearing 213. Therefore, the accuracy of the gap between the sensor stator 230 and the sensor rotor 220 of the sensor unit 200 can be improved, and the detection accuracy of the sensor unit 200 can be improved.

In particular, in the above embodiment, the sensor cover 210 includes a hollow cylindrical boss portion 212 protruding in the axial direction, a second bearing 213 is fixed to the inner peripheral surface of the boss portion 212, and the outer peripheral surface of the boss portion 212 is fixed. Since the sensor stator 230 is fixed, the rotation shaft 142 (sensor rotor 220) → the second bearing 213 → the boss portion 212 → the sensor stator 230 are aligned in this order with the rotation center of the sensor rotor 220. The concentric accuracy of the center of the sensor stator can be improved.

(4) Change example 1. In the above embodiment, the stator core 131 is sandwiched between the front flange 110 and the rear flange 120, but for example, a circular stator core may be accommodated in one frame.
2. Although the above embodiment applies the present invention to a two-phase hybrid type stepping motor, it can also be applied to a PM type (Permanent Magnet type) or VR type (Variable Reluctance type) stepping motor.

The present invention can be used for a stepping motor such as a two-phase hybrid type having a rotation angle sensor.

100 ... motor part, 110 ... front flange (frame), 111 ... boss part, 112 ... first bearing, 120 ... rear flange (frame), 121 ... boss part, 122 ... annular convex part, 123 ... space, 124 ... sleeve, 125 ... through hole, 130 ... stator, 131 ... stator core, 132 ... insulator, 133 ... coil, 140 ... rotor, 141 ... rotor core, 142 ... rotating shaft, 143 ... magnet (permanent magnet), 150 ... receptacle, 151 ... ... circuit board, 152 ... terminal pin, 200 ... sensor part, 210 ... sensor cover, 210a ... outer wall part, 211 ... annular recess, 212 ... boss part, 213 ... second bearing, 214 ... counterbore hole, 220 ... Sensor rotor, 221 ... small teeth, 230 ... sensor stator, 231 ... teeth, 232 ... insulators, 233 ... detection windings, 250 ... receptacles, 251 ... circuit boards, 252 ... terminal pins.

Claims (3)

A stepping motor provided on a frame with a stator, a rotor rotatably arranged inside the stator, and a sensor cover having a rotation angle sensor for detecting the rotation angle of the rotor.
The rotation angle sensor includes a sensor stator and a sensor rotor rotatably arranged inside the sensor stator.
The rotor includes a rotating shaft and a rotor core fixed to the rotating shaft.
A first bearing that rotatably supports the rotating shaft is arranged on one side of the frame.
The sensor cover is provided with a second bearing that rotatably supports the rotating shaft and the sensor stator.
The sensor rotor is a stepping motor fixed to the rotating shaft between the rotor core and the second bearing. The sensor cover includes a cylindrical boss portion that projects in the axial direction, the second bearing is fixed to the inner peripheral surface of the boss portion, and the sensor stator is fixed to the outer peripheral surface of the boss portion. The stepping motor according to claim 1. The stepping motor according to claim 1 or 2, wherein the stepping motor is a hybrid type stepping motor.

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