JP6795356B2 - motor - Google Patents

Description

The present invention relates to a motor including an encoder that detects rotation of a rotor by a magnetic sensitive element.

Patent Document 1 discloses a motor including an encoder that detects rotation of the rotor. In the motor of Patent Document 1, the encoder includes a magnetizing element mounted on a substrate and a magnet that rotates integrally with the output shaft of the motor. The substrate is supported by a holder fixed to the motor case. The substrate and magnet on which the magnetic sensing element is mounted are covered with a cover member. The cover member is fixed to the inner surface of the encoder case which is fixed to the motor case.

Japanese Unexamined Patent Publication No. 2016-3888

Since the encoder mounted on the motor is affected by electromagnetic noise, the output may change depending on the usage environment of the product, and the occurrence status of the angle error may change. For example, the output of the magnetizing element changes due to the influence of the disturbance magnetic field. Further, the output of the magnetically sensitive element and the amplified value of the output of the magnetically sensitive element by the encoder circuit mounted on the substrate may be affected by the frame ground noise of the motor body to which the encoder is fixed and the power supply noise.

As a countermeasure against such electromagnetic noise, Patent Document 1 uses a cover member made of a magnetic material such as iron as a cover member for covering the substrate, and the cover member functions as a magnetic shield. However, if there is a gap between the cover member and the motor case, the electromagnetic noise that wraps around the gap cannot be blocked. Further, the magnetic sensing element mounted on the substrate is not shielded from the motor case. Therefore, the influence of frame ground noise and power supply noise is large.

In view of the above problems, an object of the present invention is to reduce the influence of electromagnetic noise on the encoder in the motor provided with the encoder.

In order to solve the above problems, the motor of the present invention includes a motor body provided with a rotating shaft and a motor case, a magnet that rotates integrally with the rotating shaft, a magnetic sensing element facing the magnet, and the magnetic sensing. A substrate on which the element is mounted and having a signal ground connected to the ground terminal of the magnetically sensitive element, a substrate holder for holding the substrate, and a shield member attached to the substrate holder and covering the magnetically sensitive element. The shield member and the substrate holder are conductive members and are electrically connected to the signal ground.

In the present invention, in the motor provided with the encoder that detects the rotation of the rotating shaft, the encoder is provided with a magnetically sensitive element facing the magnet, and the magnetically sensitive element is mounted on the substrate and serves as a signal ground of the substrate. It is covered by electrically connected conductive members (board holder and shield member). By covering the magnetically sensitive element with the conductive member of the signal ground potential in this way, the influence of electromagnetic noise on the output of the magnetically sensitive element and its amplified value can be reduced. In particular, since a shield member that covers the magnetically sensitive element is provided between the magnet and the magnetically sensitive element, the influence of frame ground noise and power supply noise that wrap around from the magnet side can be effectively reduced. Therefore, the angle error of the encoder can be reduced.

In the present invention, the substrate and the conductive encoder cover for accommodating the magnet are provided, and the encoder cover and the frame ground of the motor body (for example, the flange of the bearing holder provided at the end of the motor case) are electrically connected. It is preferable to be connected. In this way, the encoder cover can be used as the frame ground potential of the motor body, so that electromagnetic noise can be effectively reduced.

In the present invention, the encoder cover is made of a magnetic material, and it is preferable that the opening edge of the encoder cover comes into contact with the motor case. In this way, since the encoder cover functions as a magnetic shield, magnetic noise such as a disturbance magnetic field can be reduced. In addition, it is possible to block the intrusion of electromagnetic noise from the gap between the motor case and the encoder cover. Therefore, the influence of electromagnetic noise can be effectively reduced.

In the present invention, it is preferable to have an insulating encoder holder that surrounds the outer peripheral side of the magnet, and the substrate holder is fixed to the motor case via the encoder holder. In this way, the member of the frame ground potential (motor case) and the member of the signal ground potential (board holder) can be insulated. Therefore, the shielding effect of each of the two grounds can be maintained.

In the present invention, it is preferable that the substrate is fixed to the substrate holder via a conductive fixing member, and the signal ground and the substrate holder are electrically connected via the fixing member. In this way, the substrate holder and the signal ground on the substrate can be electrically connected with a simple structure.

In the present invention, the fixing member is preferably a spring pin, and the substrate preferably includes a fixing hole into which the spring pin is inserted. In this way, the elasticity of the spring pin can suppress the rattling of the substrate with respect to the substrate holder. Therefore, the displacement of the substrate can be suppressed.

In the present invention, it is preferable that two or more fixing members are arranged with the center of the substrate holder interposed therebetween. In this way, the substrate can be positioned by the fixing member.

In the present invention, the substrate holder includes a substrate contact surface on which the substrate abuts in the axial direction of the rotating shaft, and a shield mounting surface on which the shield member abuts in the axial direction. It is preferable that the distance in the axial direction from the shield mounting surface is substantially the same as the distance between the substrate contact surface and the surface of the magnetizing element on the side facing the magnet . In this way, the shield mounting surface and the surface of the magnetic sensing element are located on substantially the same surface, so that the shield member can be easily mounted. For example, when the shield member is a conductive sheet material, the sheet material can be attached so as not to bend.

In the present invention, the substrate holder preferably includes a smoothed surface with which the substrate abuts. In this way, since the flatness of the surface with which the substrate abuts is high, there is little possibility that stress is applied to the substrate when the substrate is fixed. Therefore, a stable output can be obtained from the magnetic sensing element.

In the present invention, the magnet includes a first magnet in which one north pole and one south pole are magnetized in the circumferential direction, and a second magnet in which a plurality of north poles and south poles are alternately magnetized in the circumferential direction. The magnetic sensitive element includes a first magnetic sensitive element facing the first magnet and a second magnetic sensitive element facing the second magnet, and the shield member includes the first magnetic sensitive element and the said shield member. It is preferable to cover the second magnetic sensitive element. In this way, two sets of encoders, an absolute type and an incremental type, can be configured, and by processing the output, high-resolution and high-precision position detection can be performed. Further, since all the magnetic sensing elements can be covered with one shield member, the work of shielding the two sets of magnetic sensing elements is easy.

According to the present invention, in a motor provided with an encoder that detects rotation of a rotating shaft, a conductive member (board holder and shield member) in which a substrate on which the magnetizing element of the encoder is mounted is electrically connected to a signal ground of the substrate. ) Is covered. As described above, if the magnetically sensitive element is covered with the conductive member of the signal ground potential, the influence of electromagnetic noise on the output of the magnetically sensitive element and its amplified value can be reduced. In particular, since a shield member that covers the magnetically sensitive element is provided between the magnet and the magnetically sensitive element, the influence of frame ground noise and power supply noise that wrap around from the magnet side can be effectively reduced. Therefore, the angle error of the encoder can be reduced.

It is an external perspective view which shows the end part on the encoder side of the motor to which this invention was applied. It is an exploded perspective view which looked at the encoder and the bearing holder from the non-output side. It is an exploded perspective view which saw the encoder and the bearing holder from the output side. It is sectional drawing (AA sectional view of FIG. 1) of an encoder and a bearing holder. It is sectional drawing (BB sectional view of FIG. 1) of an encoder and a bearing holder. It is an exploded perspective view which looked at the substrate unit, the magnet, and the magnet holder from the non-output side. It is an exploded perspective view of a substrate unit, a magnet, and a magnet holder seen from the output side. It is sectional drawing of the substrate unit (CC sectional view of FIG. 3).

Hereinafter, embodiments of a motor to which the present invention is applied will be described with reference to the drawings. FIG. 1 is an external perspective view showing an end portion of the motor 1 to which the present invention is applied on the encoder 10 side. 2 and 3 are exploded perspective views of the encoder 10 and the bearing holder 42, FIG. 2 is an exploded perspective view seen from the non-output side, and FIG. 3 is an exploded perspective view seen from the output side. 4 and 5 are cross-sectional views of the encoder 10 and the bearing holder 42, FIG. 4 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 5 is a cross-sectional view taken along the line BB of FIG.

(overall structure)
The motor 1 includes a motor body 3 having a rotating shaft 2 (see FIGS. 4 and 5) and an encoder 10 for detecting the rotation of the rotating shaft 2. The motor body 3 includes a motor case 4 that houses a rotor and a stator (not shown). The rotor rotates integrally with the rotating shaft 2. One end of the rotating shaft 2 is an output shaft (not shown) protruding outward from the motor case 4. In the present specification, the central axis of the rotation axis 2 is indicated by reference numeral L. Further, the direction in which the output shaft protrudes from the motor case 4 is the output side L1, and the opposite side of the output side is the non-output side L2. The encoder 10 is fixed to the end of the motor body 3 on the opposite output side L2.

(Axis of rotation)
As shown in FIGS. 4 and 5, the rotary shaft 2 includes a motor-side rotary shaft 21 and an encoder-side rotary shaft 22 fixed to the end of the counter-output side L2 of the motor-side rotary shaft 21. The motor-side rotary shaft 21 and the encoder-side rotary shaft 22 rotate integrally. In this embodiment, the motor-side rotating shaft 21 is made of a magnetic material, and the encoder-side rotating shaft 22 is made of a non-magnetic material. If the encoder-side rotating shaft 22 is made of a non-magnetic material, it is possible to reduce magnetic noise that penetrates from the motor body 3 side to the encoder 10 side via the encoder-side rotating shaft 22. The rotary shaft 22 on the encoder side may be made of a magnetic material. In this case, the encoder-side rotary shaft 22 and the motor-side rotary shaft 21 may be integrated. That is, the rotating shaft 2 may be formed by one member.

(Motor case)
As shown in FIG. 1, the motor case 4 includes a tubular case 41 extending in the central axis L direction and a bearing holder 42 fixed to the end of the non-output side L2 of the tubular case 41. The tubular case 41 and the bearing holder 42 are substantially rectangular when viewed in the central axis L direction. As shown in FIGS. 2 to 5, the bearing 43 is held on the inner peripheral side of the bearing holder 42. The bearing 43 rotatably supports the end of the output side L1 of the encoder side rotary shaft 22. As shown in FIG. 2, a circular recess 44 recessed in the output side L1 is formed on the surface of the bearing holder 42 on the opposite output side L2, and a flange 45 is formed on the outer peripheral side of the circular recess 44. An annular wall 46 is formed on the inner peripheral edge of the flange 45 so as to project toward the counter-output side L2 along the edge of the circular recess 44.

An annular plate 47 is attached to the bottom of the circular recess 44 so as to press the outer peripheral portion of the bearing 43 from the counter-output side L2. The encoder-side rotating shaft 22 projects to the counter-output side L2 through the through hole 48 provided in the center of the plate 47. The plate 47 is fixed to the bottom of the circular recess 44 by three screws. Notches 49 are formed on the outer peripheral edge of the plate 47 at three equiangular intervals. The leg portion 143 of the encoder holder 14, which will be described later, is arranged in the notch 49.

(Encoder)
As shown in FIGS. 2 to 5, the encoder 10 includes an outer case 11 fixed to the bearing holder 42, an encoder cover 12 arranged inside the outer case 11, and a substrate arranged inside the encoder cover 12. A unit 13, an encoder holder 14 that supports the substrate unit 13, a magnet holder 15 arranged on the inner peripheral side of the encoder holder 14, and a magnet 16 held by the magnet holder 15 are provided. The magnet holder 15 is fixed to the tip of the counter-output side L2 of the encoder-side rotating shaft 22. Therefore, the magnet 16 rotates integrally with the encoder-side rotating shaft 22. The substrate unit 13 includes a magnetic sensing element 17 (see FIG. 7) facing the magnet 16. In this embodiment, an MR element is used as the magnetic sensing element 17.

(Outer case)
As shown in FIGS. 2 and 3, the outer case 11 has a substantially rectangular end plate portion 111 when viewed in the central axis L direction, and a side plate portion 112 rising from the outer peripheral edge of the end plate portion 111 to the output side L1. Be prepared. The side plate portion 112 is formed with a notch 113 for passing the wiring connected to the substrate unit 13. In the outer case 11 and the bearing holder 42, a sealing member 114 is interposed between the end surface of the output side L1 of the side plate portion 112 and the flange 45, and fixing members such as screws (not shown) are tightened at four corners. Fixed by. In this embodiment, the outer case 11 and the motor case 4 are made of a non-magnetic material such as aluminum. In this embodiment, the outer case 11 is a separate member from the encoder cover 12 described below, but the outer case 11 may be integrally formed of the same material as the encoder cover 12.

(Encoder cover)
As shown in FIGS. 2 and 3, the encoder cover 12 has a circular end plate portion 121 when viewed in the central axis L direction, and a tubular portion 122 that rises from the outer peripheral edge of the end plate portion 121 to the output side L1. Be prepared. The tubular portion 122 is formed with a notch 123 for passing the wiring connected to the substrate unit 13 at a position overlapping the notch 113 of the outer case 11 in the radial direction. As shown in FIGS. 4 and 5, the encoder cover 12 fits the edge of the tubular portion 122 on the inner peripheral side of the annular wall 46 formed along the edge of the circular recess 44 of the bearing holder 42. It is assembled to the bearing holder 42. The end surface of the output side L1 of the tubular portion 122 abuts on the plate 47 arranged at the bottom of the circular recess 44, except for the portion where the notch 123 is formed. Here, the ring road 46
Is partially cut out in the circumferential direction, but the portion where the annular wall 46 is cut out is at an angle position different from that of the cutout 49 formed on the outer peripheral edge of the plate 47. Therefore, the gap between the encoder cover 12 and the bearing holder 42 is closed except for the notch 123.

The encoder cover 12 is made of a conductive magnetic material. For example, the encoder cover 12 is made of iron, permalloy, or the like. More specifically, the encoder cover 12 is formed by pressing a magnetic metal plate such as SPCC or SPCE. By covering the substrate unit 13 that holds the magnetic sensitive element 17 with the encoder cover 12 made of the magnetic material in this way, the magnetic sensitive element 17 and the encoder circuit can be shielded from magnetic noise such as a disturbance magnetic field. Further, the encoder cover 12 is attached so that there is almost no gap between the encoder cover 12 and the bearing holder 42. Therefore, it is possible to prevent electromagnetic noise from entering the substrate unit 13 side through the gap with the bearing holder 42.

Since the encoder cover 12 is attached so as to come into contact with the bearing holder 42, it is electrically connected to the frame ground of the motor body 3. That is, the bearing holder 42 constitutes a part of the motor case 4 made of a conductive metal such as aluminum. Therefore, the encoder cover 12 is electrically connected to the frame ground of the motor body 3 by fitting the tubular portion 122 of the encoder cover 12 inside the annular wall 46 provided in the bearing holder 42. By connecting the encoder to the frame ground potential in this way, the shielding effect of electromagnetic noise can be enhanced. Even if the tubular portion 122 of the encoder cover 12 is not fitted inside the annular wall 46, if the end surface of the tubular portion 122 of the encoder cover 12 is fixed so as to come into contact with the bottom of the circular recess 44, It can be connected to the frame ground potential of the encoder cover 12 and the motor body 3.

(Encoder holder)
As shown in FIGS. 2 and 3, the encoder holder 14 includes a body portion 142 in which a circular magnet arrangement hole 141 is formed, and a leg portion 143 that protrudes from the end of the output side L1 of the body portion 142 to the outer peripheral side. Be prepared. As shown in FIG. 3, the end surface of the output side L1 of the leg portion 143 projects toward the output side L1 from the end surface of the output side L1 of the body portion 142. The leg portions 143 are formed at three positions at equal angular intervals in the circumferential direction. The encoder holder 14 is positioned so that the central axis L of the encoder-side rotary shaft 22 rotatably held in the center of the bearing holder 42 and the magnet arrangement hole 141 are arranged coaxially, and the above-mentioned plate 47 The leg portion 143 is positioned so as to be arranged in the notch 49 formed on the outer peripheral edge. As shown in FIG. 5, the encoder holder 14 comes into contact with the bearing holder 42 via the leg portion 143. The encoder holder 14 is fixed to the bearing holder 42 by screwing the leg portion 143 to the bottom surface of the circular recess 44 by a fixing screw (not shown).

In the encoder holder 14, fixing holes 144 for fixing the substrate unit 13 are formed at three places on the end surface of the counter-output side L2 of the body portion 142. The substrate unit 13 is positioned so as to abut on the end surface of the counter-output side L2 of the body portion 142, and is fixed to the encoder holder 14 via a fixing member such as a screw (not shown).

(magnet)
6 and 7 are exploded perspective views of the substrate unit 13, the magnet 16, and the magnet holder 15, FIG. 6 is a view seen from the non-output side, and FIG. 7 is a view seen from the output side. As shown in FIGS. 6 and 7, the magnet holder 15 includes a substantially disk-shaped magnet holding portion 151 and a tubular fixing portion 152 projecting from the center of the magnet holding portion 151 to the output side L1. The tip of the encoder-side rotating shaft 22 is press-fitted or fixed to the fixing portion 152 by press fitting or an adhesive. The magnet 16 includes a circular first magnet 161 that fits in a recess formed in the center of the magnet holding portion 151, and an annular second magnet 162 that fits in a step portion formed on the outer peripheral edge of the first magnet. To be equipped with. The first magnet 161 is magnetized with one north pole and one south pole in the circumferential direction. On the other hand, in the second magnet 162, the north pole and the south pole are alternately magnetized in the circumferential direction by a plurality of poles.

As shown in FIGS. 4 and 5, when the encoder holder 14 is fixed to the bearing holder 42, the tip of the encoder-side rotary shaft 22 is arranged in the center of the magnet arrangement hole 141 of the encoder holder 14. Therefore, the magnet holder 15 fixed to the tip of the encoder-side rotation shaft 22 is arranged at the center of the magnet arrangement hole 141. The first magnet 161 and the second magnet 162 are arranged in the magnet arrangement hole 141 so as to face the counter-output side L2, and are arranged coaxially with the central axis L of the encoder side rotation shaft 22 as the center.

(Board unit)
FIG. 8 is a cross-sectional view of the substrate unit 13 (CC cross-sectional view of FIG. 3). As shown in FIGS. 6 and 7, the substrate unit 13 fixes the substrate 60 to the substrate holder 50, the substrate 60 attached to the substrate holder 50, the magnetic sensitive element 17 mounted on the substrate 60, and the substrate holder 50. A fixing member 70 to be attached and a shield member 80 attached to the substrate holder 50 from the counter-output side L2 are provided. The substrate 60 is substantially circular and includes a notch 61 in which one portion of the outer peripheral edge is linearly cut out. Further, the substrate 60 is formed with fixing holes 62 for fixing to the substrate holder 50 at two locations. The two fixing holes 62 are arranged on opposite sides of the center of the substrate holder 50. Further, one of the two fixing holes 62 is a ground through hole 621 electrically connected to the signal ground of the encoder circuit mounted on the substrate 60. Either of the two fixing holes may be the ground through hole 621. Further, the substrate 60 and the substrate holder 50 may be fixed at three or more fixing holes 62.

The substrate holder 50 is formed with boss portions 51 corresponding to the fixing holes 62 at two locations. The substrate 60 is fixed to the substrate holder 50 by inserting the fixing member 70 into the fixing hole 62 and the boss portion 51. The fixing member 70 is a spring pin. By using the spring pin as the fixing member 70, rattling of the substrate 60 with respect to the substrate holder 50 is prevented. Further, the fixing member 70 is made of a conductive metal, and the substrate holder 50 is made of a conductive metal, for example, aluminum. Therefore, when the substrate 60 is attached to the substrate holder 50 via the fixing member 70, the substrate holder 50 is electrically connected to the signal ground of the encoder circuit mounted on the substrate 60 via the fixing member 70 and the ground through hole 621. Be connected.

The substrate holder 50 is formed with fixing holes 52 at three locations corresponding to the fixing holes 144 of the encoder holder 14 described above. Further, the substrate 60 is formed with fixing holes 63 at three locations corresponding to the fixing holes 52 and 144. The substrate unit 13 is fixed to the encoder holder 14 by screwing a fixing member such as a screw inserted into the fixing holes 52 and 63 into the fixing hole 144. As described above, since the encoder holder 14 abuts and is fixed to the bearing holder 42, the substrate unit 13 is fixed to the bearing holder 42 via the encoder holder 14. In this embodiment, the encoder holder 14 is made of an insulating material such as resin. Therefore, when the substrate unit 13 is fixed to the bearing holder 42 via the encoder holder 14, the substrate unit 13 is insulated from the bearing holder 42. As a result, the substrate unit 13 is insulated from the motor case 4 and from the frame ground of the motor body 3. By insulating the substrate unit 13 from the frame ground of the motor body 3 in this way, the influence of frame ground noise and power supply noise can be suppressed.

The substrate 60 includes an anti-output side substrate surface 60a facing the anti-output side L2 and an output side substrate surface 60b facing the output side L1. A circuit element 64 such as an operational amplifier constituting an encoder circuit, a connector 65 for wiring connection, and the like are mounted on the non-output side substrate surface 60a. On the other hand, the magnetic sensing element 17 is mounted on the output side substrate surface 60b. The magnetic sensing element 17 is via a first magnetic sensing element 171 arranged in the center of the output side substrate surface 60b, a connection terminal 173 provided at a position near the outer periphery of the output side substrate surface 60b, and a flexible wiring board 174. The second magnetic sensitive element 172 to be connected is provided. Each of the first magnetic sensing element 171 and the second magnetic sensing element 172 includes a ground terminal (not shown) connected to a signal ground of an encoder circuit configured on the substrate 60. Further, on the output side substrate surface 60b, two Hall elements 175 are mounted in the vicinity of the first magnetic sensing element 171. The two Hall elements 175 are arranged at an angle position 90 degrees apart.

As shown in FIGS. 6 and 8, the substrate holder 50 includes an end plate portion 53 facing the substrate 60 and a side plate portion 54 rising from the outer peripheral edge of the end plate portion 53 to the counter-output side L2. In the end plate portion 53 and the side plate portion 54, a portion overlapping the notch 61 of the substrate 60 is formed in a straight line. The end surface of the counter-output side L2 of the side plate portion 54 is a substrate contact surface 55 with which the substrate 60 abuts. In this embodiment, the substrate contact surface 55 is a surface (that is, a smoothed surface) that has been processed to increase the flatness. Specifically, the flatness of the substrate contact surface 55 is increased by lace processing. Alternatively, the flatness may be increased by grinding or polishing. The outer peripheral edge of the substrate 60 comes into contact with the substrate contact surface 55 over the entire circumference. By increasing the flatness of the substrate contact surface 55, it is possible to suppress the stress applied to the substrate 60 when the substrate 60 is fixed to the substrate holder 50.

As shown in FIGS. 6 and 7, a circular first through hole 56 is formed in the center of the substrate holder 50. Further, as shown in FIG. 7, in the substrate holder 50, a step portion 57 projecting to the output side L1 is formed on the surface of the output side L1 of the end plate portion 53. The step portion 57 includes a portion formed in an annular shape around the first through hole 56 and a portion extending in a strip shape with a constant width to the outer peripheral edge of the end plate portion 53. A substantially rectangular second through hole 58 is formed in a portion of the step portion 57 near the outer circumference. When the substrate 60 is fixed to the substrate holder 50, the first magnetic sensing element 171 and the Hall element 175 are arranged in the first through hole 56. Further, the second magnetic sensing element 172 is arranged in the second through hole 58 (see FIG. 8).

When the substrate unit 13 is fixed to the encoder holder 14, the first magnetic sensing element 171 arranged in the first through hole 56 of the substrate holder 50 and the first magnet 161 face each other (see FIGS. 4 and 5). Further, the second magnetic sensing element 172 arranged in the second through hole 58 of the substrate holder 50 and the second magnet 162 face each other. The encoder 10 is predetermined between the surface 171a of the output side L1 of the first magnetic sensing element and the first magnet 161 and between the surface 172a of the output side L1 of the second magnetic sensing element 172 and the second magnet 162. It is configured to form a gap.

The first magnetizing element 171 and the two Hall elements 175 and the first magnet 161 arranged in the vicinity thereof determine the output cycle of the first magnetic sensing element 171 obtained by one rotation by the two Hall elements 175. By doing so, it functions as an absolute encoder. On the other hand, the second magnetic sensing element 172 and the second magnet 162 function as incremental encoders because outputs of a plurality of cycles can be obtained in one rotation. By processing the outputs of these two sets of encoders, the encoder 10 can perform position detection with high resolution and high accuracy.

(Shield member)
The shield member 80 is attached to the stepped portion 57 of the substrate holder 50 from the counter-output side L2. The shield member 80 of the present embodiment is a flexible sheet material, and has a size that completely closes the first through hole 56 and the second through hole 58 formed in the step portion 57. The step portion 57 includes a shield mounting surface 59 facing the counter-output side L2, and the shield member 80 comes into contact with the shield mounting surface 59. Like the substrate holder 50, the shield member 80 is made of a conductive non-magnetic metal, for example, aluminum. Then, the shield member 80 is adhered to the shield mounting surface 59 via a conductive adhesive. Therefore, the shield member 80 is electrically connected to the signal ground of the encoder circuit mounted on the substrate 60 via the substrate holder 50.

The shield member 80 is attached to the substrate holder 50 so as to cover the first magnetic sensing element 171 arranged in the first through hole 56 and the second magnetic sensing element 172 arranged in the second through hole 58. By attaching the shield member 80 to the substrate holder 50, the first magnetic sensing element 171 and the second magnetic sensing element 172 are shielded from the motor body 3 by the signal ground potential members (board holder 50 and shield member 80). .. Therefore, it is possible to effectively shield the frame ground noise and the power supply noise that wrap around from the gap between the first magnet 161 and the second magnet 162. The first magnetic sensing element 171 and the second magnetic sensing element 172 face the first magnet 161 and the second magnet via the shield member 80, but since the shield member 80 is a non-magnetic metal, electromagnetic noise Can shield well and not impair its function as a magnetic encoder.

As shown in FIG. 8, in the substrate unit 13, the distance t between the substrate contact surface 55 in contact with the output side substrate surface 60b of the substrate 60 and the shield mounting surface 59 to which the shield member 80 is attached is the substrate contact surface. The distance between 55 and the surface 171a of the output side L1 of the first magnetic sensing element is the same. Here, the substrate 60 abuts on the substrate contact surface 55 in the central axis L direction (axis direction). Further, the shield member 80 comes into contact with the shield mounting surface 59 in the L direction of the central axis. The above-mentioned distance t is a distance in the central axis L direction. Therefore, the substrate holder 50 is configured so that the surface 171a of the output side L1 of the first magnetic sensing element 171 is located on the same surface as the shield mounting surface 59. Further, the surface 172a of the output side L1 of the second magnetic sensitive element 172 is located on the same surface as the surface 171a of the output side L1 of the first magnetic sensitive element and the shield mounting surface 59, and is located on the same surface as the substrate contact surface 55 and the output. The distance of the side L1 from the surface 172a is configured to be the same as the distance t between the substrate contact surface 55 and the shield mounting surface 59 in the central axis L direction. In such a configuration, when the shield member 80 is attached to the shield attachment surface 59, the shield member 80 can be attached so as not to bend. Therefore, the work of attaching the shield member 80 is easy. Further, there is little possibility that a gap is formed between the shield member 80 and the shield mounting surface 59.

(Main action and effect of this form)
As described above, in the present embodiment, in the motor 1 including the encoder 10 for detecting the rotation of the rotating shaft 2, the encoder 10 is magnetized by the magnets 16 (first magnet 161 and second magnet 162) and facing the magnet 16. The element 17 (first magnetic sensing element 171 and second magnetic sensing element 172) is provided. The magnetic sensing element 17 is mounted on the substrate 60 and is covered from the motor body 3 side by conductive members (board holder 50 and shield member 80) electrically connected to the signal ground of the substrate 60. By covering the magnetic sensing element 17 with the member of the signal ground potential in this way, the influence of electromagnetic noise on the output of the magnetic sensing element 17 and its amplification value can be reduced. In particular, since the shield member 80 that covers the magnetic sensing element 17 is provided between the magnet 16 and the magnetic sensing element 17, the influence of frame ground noise and power supply noise that wraps around from the magnet 16 side can be effectively reduced. .. Therefore, the angle error of the encoder 10 can be reduced.

The encoder 10 of this embodiment has a substrate unit 13 on which a magnetic sensing element 17 is mounted and a conductive encoder cover 12 that houses a magnet 16, and the encoder cover 12 is a bearing provided at an end of a motor case 4. It is electrically connected to the holder 42. As a result, the encoder cover 12 can be used as the frame ground potential of the motor body 3, so that electromagnetic noise can be effectively reduced.

In this embodiment, the encoder cover 12 is made of a magnetic material such as iron or permalloy, and the opening edge of the encoder cover 12 comes into contact with the flange 45 of the bearing holder 42. Therefore, since the encoder cover 12 functions as a magnetic shield, magnetic noise such as a disturbance magnetic field can be reduced. Further, it is possible to block the intrusion of electromagnetic noise from the gap between the flange 45 and the encoder cover 12. Therefore, the influence of electromagnetic noise can be effectively reduced.

The encoder 10 of this embodiment has an insulating encoder holder 14 that surrounds the magnet 16 and the outer peripheral side of the magnet holder 15, and the substrate holder 50 is fixed to the bearing holder 42 via the encoder holder 14. As a result, the member of the frame ground potential (bearing holder 42) and the member of the signal ground potential (board holder 50) can be insulated, so that the shielding effect of each of the two grounds can be maintained.

In the present embodiment, the substrate 60 on which the magnetic sensing element 17 is mounted is fixed to the substrate holder 50 via the conductive fixing member 70, and is fixed to the substrate holder 50 via the ground through hole 621 and the fixing member 70 provided in the substrate 60. The signal ground and the substrate holder 50 are electrically connected. Therefore, the substrate holder 50 and the signal ground on the substrate 60 can be electrically connected with a simple structure.

In this embodiment, since the fixing member 70 is a spring pin, the elasticity of the spring pin can suppress the rattling of the substrate 60 with respect to the substrate holder 50. Therefore, the displacement of the substrate can be suppressed. Further, two fixing members 70 are arranged so as to sandwich the center of the substrate holder 50. Therefore, the fixing member 70 can position the substrate.

In the present embodiment, the substrate holder 50 includes a substrate contact surface 55 with which the substrate 60 abuts and a shield mounting surface 59 with which the shield member 80 abuts, and the central axis L of the substrate contact surface 55 and the shield mounting surface 59. The distance t in the direction is substantially the same as the distance between the substrate contact surface 55 and the surface 171a of the output side L1 of the first magnetic sensing element 171 and the distance 172a of the output side L1 of the second magnetic sensing element 172. is there. As described above, when the shield mounting surface 59 and the surfaces 171a and 172a of the output side L1 are located on substantially the same surface, the shield member 80 can be easily mounted. For example, when the shield member is a conductive sheet material, it can be attached so as not to bend, so that it is easy to attach.

In this embodiment, the substrate contact surface 55 of the substrate holder 50 is a smoothed surface, and is, for example, lace-processed. If the flatness of the substrate contact surface 55 is increased in this way, there is little possibility that stress will be applied to the substrate 60 when the substrate 60 is brought into contact with and fixed. Therefore, a stable output can be obtained from the magnetic sensing element 17. The substrate 60 may be provided with a slit for stress relief. For example, a slit can be provided between the area where the magnetic sensing element 17 is attached and the fixing hole for fixing the substrate 60.

In this embodiment, two sets of magnetic sensing elements 17 and magnets 16 (first magnetic sensing element 171 and first magnet 161 and second magnetic sensing elements 172 and first) for forming two sets of absolute type and incremental type encoders. Since it is equipped with two magnets 162), it is possible to perform position detection with high resolution and high accuracy. Further, since all the magnetic sensing elements 17 can be covered with one shield member 80, the work of shielding the magnetic sensing elements 17 is easy.

1 ... motor, 2 ... rotating shaft, 3 ... motor body, 4 ... motor case, 10 ... encoder, 11 ... outer case, 12 ... encoder cover, 13 ... board unit, 14 ... encoder holder, 15 ... magnet holder, 16 ... Magnet, 17 ... Magnetic element, 21 ... Motor side rotating shaft, 22 ... Encoder side rotating shaft, 41 ... Cylindrical case, 42 ... Bearing holder, 43 ... Bearing, 44 ... Circular recess, 45 ... Flange, 46 ... Annular wall , 47 ... Plate, 48 ... Through hole, 49 ... Notch, 50 ... Board holder, 51 ... Boss part, 52 ... Fixed hole, 53 ... End plate part, 54 ... Side plate part, 55 ... Board contact surface, 56 ... 1st through hole, 57 ... stepped portion, 58 ... 2nd through hole, 59 ... shield mounting surface,
60 ... Board, 60a ... Non-output side board surface, 60b ... Output side board surface, 61 ... Notch, 62 ... Fixed hole, 63 ... Fixed hole, 64 ... Circuit element, 65 ... Connector, 70 ... Fixed member, 80 ... Shield member, 111 ... end plate part, 112 ... side plate part, 113 ... notch, 114 ... seal member, 121 ... end plate part, 122 ... tubular part, 123 ... notch, 141 ... magnet placement hole, 142 ... body Part, 143 ... Leg part, 144 ... Fixed hole, 151 ... Magnet holding part, 152 ... Fixed part, 161 ... First magnet, 162 ... Second magnet, 171 ... First magnetic sensing element, 171a ... Output side surface, 172 ... 2nd magnetic sensitive element, 172a ... Output side surface, 173 ... Connection terminal, 174 ... Flexible wiring board, 175 ... Hall element, 621 ... Ground through hole, L ... Central axis, L1 ... Output side, L2 ... Anti Output side, t ... distance

Claims (10)

A motor body with a rotating shaft and a motor case,
A magnet that rotates integrally with the rotating shaft,
The magnetoreceptive element facing the magnet and
A substrate on which the magnetically sensitive element is mounted and having a signal ground connected to the ground terminal of the magnetically sensitive element.
A board holder that holds the board and
It has a shield member that is attached to the substrate holder and covers the magnetic sensing element.
A motor in which the shield member and the substrate holder are conductive members and are electrically connected to the signal ground. It has a conductive encoder cover that houses the substrate and the magnet.
The motor according to claim 1, wherein the encoder cover and the frame ground of the motor body are electrically connected. The encoder cover is made of a magnetic material.
The motor according to claim 2, wherein the opening edge of the encoder cover comes into contact with the motor case. It has an insulating encoder holder that surrounds the outer peripheral side of the magnet.
The motor according to any one of claims 1 to 3, wherein the substrate holder is fixed to the motor case via the encoder holder. The substrate is fixed to the substrate holder via a conductive fixing member.
The motor according to any one of claims 1 to 4, wherein the signal ground and the substrate holder are electrically connected via the fixing member. The fixing member is a spring pin.
The motor according to claim 5, wherein the substrate includes a fixing hole into which the spring pin is inserted. The motor according to claim 5 or 6, wherein two or more fixing members are arranged with the center of the substrate holder interposed therebetween. The substrate holder includes a substrate contact surface with which the substrate abuts in the axial direction of the rotation axis, and a shield mounting surface with which the shield member abuts in the axial direction.
The distance between the substrate contact surface and the shield mounting surface in the axial direction is substantially the same as the distance between the substrate contact surface and the surface of the magnetizing element on the side facing the magnet. The motor according to any one of claims 1 to 7.
The motor according to any one of claims 1 to 8, wherein the substrate holder includes a smoothed surface with which the substrate abuts. The magnet includes a first magnet in which one north pole and one south pole are magnetized in the circumferential direction, and a second magnet in which a plurality of north poles and south poles are alternately magnetized in the circumferential direction.
The magnetic sensing element includes a first magnetic sensing element facing the first magnet and a second magnetic sensing element facing the second magnet.
The motor according to any one of claims 1 to 8, wherein the shield member covers the first magnetically sensitive element and the second magnetically sensitive element.

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