JP7171380B2 - motor - Google Patents

Description

The present invention relates to motors.

Conventionally, various motors have been used. Among these, for example, in Patent Document 1, a first magnet magnetized with one N pole and one S pole, and a magnet provided around the first magnet with a large number of magnetizations (N pole and S a second magnet having a plurality of magnetized poles, a magnet holder rotatable together with both the first magnet and the second magnet, and a first magneto-sensitive magnet facing the first magnet. A motor is disclosed comprising a substrate unit having an element and a second magneto-sensitive element facing the second magnet.

2018-42332 publication

However, in the motor of Patent Document 1, since the first magneto-sensitive element is provided on the substrate and the second magneto-sensitive element is provided on the substrate holder which is a member different from the substrate, the motor consists of the substrate and the substrate holder. Assembling the board unit may be troublesome. Also, since the number of magnetizations of the second magnet is large and the magnetic flux does not reach far, the magnetic detection by the second magneto-sensitive element is highly sensitive when the distance between the second magneto-sensitive element and the second magnet is large. Magnetic detection can be difficult.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a motor that is simple to form and has high sensitivity.

A motor according to the present invention includes a first magnet magnetized with one N pole and one S pole, and a second magnet magnetized with a plurality of N poles and S poles, wherein the first magnet and the second magnet, a magnet holder rotatable together with both magnets, a first magneto-sensitive element provided facing the first magnet in the direction of the rotation axis of the magnet holder, and the first magnet in the direction of the axis of rotation of the magnet holder. a substrate on which two magnets and a second magneto-sensitive element facing each other are mounted, wherein the second magneto-sensitive element protrudes toward the magnet side more than the first magneto-sensitive element. characterized by

According to this aspect, since both the first magneto-sensitive element and the second magneto-sensitive element are mounted on the substrate, it is possible to easily assemble the substrate unit. Moreover, since the second magneto-sensitive element protrudes toward the magnet side more than the first magneto-sensitive element, the distance between the second magneto-sensitive element and the second magnet can be easily narrowed. Therefore, it is possible to provide a motor that can be easily formed and has high magnetic detection sensitivity.

The motor of the present invention includes a substrate holder that covers the substrate on the side of the magnet in the rotation axis direction, and the substrate is a signal ground connected to ground terminals of the first and second magneto-sensitive elements. wherein the substrate holder has an opening at the position of the second magneto-sensitive element when viewed from the direction of the rotation axis, and the opening has a thickness in the direction of the rotation axis that is thinner than that of the substrate holder. It is preferable that the substrate holder and the shield member are both covered with a member, formed of a conductive member, and connected to the signal ground. By shielding the second magneto-sensitive element with a thin shield member, noise (frame ground noise, power supply noise, etc.) from the magnet side can be blocked from the second magneto-sensitive element while keeping the distance between the second magneto-sensitive element and the second magnet narrow. ) can be prevented from invading and affecting the magnetic detection result.

In the motor of the present invention, it is preferable that a position of the first magneto-sensitive element facing the first magnet is covered with the substrate holder. This is because it is possible to prevent noise from entering the first magneto-sensitive element from the magnet side and affecting the magnetism detection result with a simple configuration.

In the motor of the present invention, it is preferable that the second magneto-sensitive element does not protrude beyond the substrate holder toward the second magnet. This is because the second magneto-sensitive element can be prevented from coming into contact with other members. Moreover, when the shield member is attached to the substrate holder, the shield member can be easily attached without being deformed.

In the motor of the present invention, it is preferable that the distance between the second magneto-sensitive element and the second magnet is narrower than the distance between the first magneto-sensitive element and the first magnet. The number of magnetization of the second magnet is greater than that of the first magnet, and the magnetic flux does not reach as far as the first magnet. This is because, by making the distance narrower than the distance between and, both the first magneto-sensitive element and the second magneto-sensitive element can detect magnetism with high sensitivity.

In the motor of the present invention, the second magneto-sensitive element has a magneto-sensitive film, and the position of the magneto-sensitive film on the second magneto-sensitive element in the direction of the rotation axis corresponds to the position of the second magneto-sensitive element in the direction of the axis of rotation. It is preferably closer to the second magnet than the center of the magnetic element. This is because the position of the magnetosensitive film can be brought closer to the magnet, and it is possible to detect magnetism with particularly high sensitivity.

In the motor of the present invention, the second magnet is arranged around the first magnet, and a shield wall is provided along the entire circumference between the first magnet and the second magnet. Preferably, the shield wall does not protrude beyond the second magnet toward the substrate. By providing a shield wall that does not extend beyond the second magnet between the first magnet and the second magnet, the effect of the magnetic flux from the first magnet toward the second magnet is suppressed while the shield wall extends beyond the second magnet. It is possible to suppress the magnetic flux of the second magnet from being directed toward the shield wall and weakening the magnetic flux toward the second magneto-sensitive element as compared with the case where there is.

In the motor of the present invention, it is preferable that the shield wall protrudes toward the substrate beyond the first magnet. This is because the influence of the magnetic flux from the first magnet toward the second magnet can be suppressed by the shield wall projecting beyond the first magnet toward the substrate.

In the motor of the present invention, it is preferable that the second magnet is magnetized while being fixed to the magnet holder. This is because misalignment of the center of the second magnet with respect to the rotation axis can be suppressed.

INDUSTRIAL APPLICABILITY The present invention can provide a motor that can be easily formed and has high magnetic detection sensitivity.

1 is an external perspective view showing an encoder-side end of a motor to which the present invention is applied; FIG. FIG. 4 is an exploded perspective view of the encoder and the bearing holder as seen from the counter-output side; FIG. 4 is an exploded perspective view of the encoder and bearing holder as seen from the output side; FIG. 2 is a cross-sectional view of an encoder and a bearing holder (a cross-sectional view taken along line AA in FIG. 1); FIG. 2 is a cross-sectional view of the encoder and the bearing holder (cross-sectional view taken along line BB in FIG. 1); FIG. 4 is an exploded perspective view of the board unit, magnets, and magnet holders as seen from the anti-output side; 4 is an exploded perspective view of the board unit, magnets, and magnet holders viewed from the output side; FIG. FIG. 4 is a plan view showing a layout of a rotary magnet and a magneto-sensitive element sensor section of an encoder of a motor to which the present invention is applied; FIG. 4 is a perspective view showing a layout of a rotary magnet and a magneto-sensitive element sensor section of an encoder of a motor to which the present invention is applied; FIG. 4 is a phase diagram for explaining the detection principle in an encoder to which the present invention is applied; FIG. 4 is a diagram for explaining a detection principle in an encoder to which the present invention is applied; FIG. 4 is a schematic diagram showing the layout of a rotating magnet and a magneto-sensitive element sensor section of an encoder of a motor to which the present invention is applied;

An embodiment of a motor to which the present invention is applied will be described below with reference to the drawings. FIG. 1 is an external perspective view showing an end portion of a 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 being a cross-sectional view taken along line AA in FIG. 1, and FIG. 5 being a cross-sectional view along line BB in 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 rotation of the rotating shaft 2 . The motor body 3 includes a motor case 4 that accommodates a rotor and a stator (not shown). The rotor rotates integrally with the rotating shaft 2 . One end of the rotating shaft 2 serves as an output shaft (not shown) protruding from the motor case 4 to the outside. In this specification, the central axis (rotational axis) of the rotating shaft 2 is denoted by L. As shown in FIG. Note that the rotation axis L corresponds to the rotation axis of the magnet holder 15 . The direction in which the output shaft protrudes from the motor case 4 is the output side L1, and the opposite side to the output side is the non-output side L2. The encoder 10 is fixed to the end of the motor body 3 opposite to the 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 motor-side rotary shaft 21 on the counter-output side L2. The motor-side rotating shaft 21 and the encoder-side rotating shaft 22 rotate together. 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 rotary shaft 22 is made of a non-magnetic material, magnetic noise that enters from the motor main body 3 side to the encoder 10 side via the encoder-side rotary shaft 22 can be reduced. Note that the encoder-side rotating shaft 22 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 cylindrical case 41 extending in the direction of the rotation axis L, and a bearing holder 42 fixed to the end of the cylindrical case 41 on the counter-output side L2. The tubular case 41 and the bearing holder 42 are substantially rectangular when viewed in the rotation axis L direction. As shown in FIGS. 2 to 5, a bearing 43 is held on the inner peripheral side of the bearing holder 42 . The bearing 43 rotatably supports the output-side L1 end of the encoder-side rotary shaft 22 . As shown in FIG. 2, a circular recess 44 recessed toward the output side L1 is formed on the surface of the bearing holder 42 opposite to the output side L2, and a flange 45 is formed on the outer peripheral side of the circular recess 44. As shown in FIG. An annular wall 46 is formed on the inner peripheral edge of the flange 45 and protrudes 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 anti-output side L2. The encoder-side rotary shaft 22 protrudes toward the counter-output side L2 through a through hole 48 provided in the center of the plate 47 . Plate 47 is secured to the bottom of circular recess 44 by three screws. Three notches 49 are formed at equal angular intervals on the outer peripheral edge of the plate 47 . A leg portion 143 of the encoder holder 14 to 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 a bearing holder 42, an encoder cover 12 arranged inside the outer case 11, and a substrate arranged inside the encoder cover 12. It includes 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 (rotating magnet) held by the magnet holder 15. The magnet holder 15 is fixed to the tip of the encoder-side rotary shaft 22 on the counter-output side L2. Therefore, the magnet 16 rotates integrally with the encoder-side rotating shaft 22 . The substrate unit 13 includes a magneto-sensitive element 17 (magneto-sensitive element sensor section) facing the magnet 16 . In this embodiment, an MR element is used as the magneto-sensitive element 17 .

(outer case)
As shown in FIGS. 2 and 3, the outer case 11 has an end plate portion 111 which is substantially rectangular when viewed in the direction of the rotation axis L, and a side plate portion 112 rising from the outer peripheral edge of the end plate portion 111 toward the output side L1. Prepare. A notch 113 is formed in the side plate portion 112 for passing a wiring connected to the board unit 13 . In the outer case 11 and the bearing holder 42, a seal member 114 is interposed between the end face 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 corner portions. 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 and the encoder cover 12 may be formed integrally from the same material.

(encoder cover)
As shown in FIGS. 2 and 3, the encoder cover 12 has a circular end plate portion 121 when viewed in the direction of the rotation axis L, and a cylindrical portion 122 rising from the outer peripheral edge of the end plate portion 121 toward the output side L1. Prepare. The cylindrical portion 122 has a notch 123 formed at a position overlapping the notch 113 of the outer case 11 in the radial direction for passing the wiring connected to the board unit 13 . As shown in FIGS. 4 and 5, the encoder cover 12 is arranged so that the edge of the cylindrical portion 122 is fitted to 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 attached to the bearing holder 42 . The end surface of the cylindrical portion 122 on the output side L1 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 annular wall 46 is partially cut away in the circumferential direction, but the cutout portion of the annular wall 46 is at a different angular position from the cutout 49 formed in 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. Thus, by covering the substrate unit 13 holding the magneto-sensitive element 17 with the encoder cover 12 made of a magnetic material, the magneto-sensitive element 17 and the encoder circuit can be shielded from magnetic noise such as disturbance magnetic fields. Also, the encoder cover 12 is attached so that there is almost no gap between the bearing holder 42 and the encoder cover 12 . Therefore, it is possible to suppress electromagnetic wave noise from entering the substrate unit 13 side through the gap with the bearing holder 42 .

As another means, the encoder cover 12 may be attached to the substrate holder 50 of the substrate unit 13 so that there is no gap therebetween, thereby suppressing the intrusion of electromagnetic wave noise. Specifically, the tubular portion 122 of the encoder cover 12 extends to the outer peripheral side of the substrate unit 13 , and the tip of the tubular portion 122 protrudes from the outer peripheral edge of the substrate holder 50 toward the output side L1. In other words, the cylindrical portion 122 extends from the magneto-sensitive element 17 mounted on the substrate 60 to the position on the output side L1, and the cylindrical portion 122 surrounds the outer peripheral side of the magneto-sensitive element 17 to prevent electromagnetic noise from entering. can be suppressed. In that case, it is desirable to electrically connect to the signal ground of the encoder circuit on the substrate 60 via the conductive fixing member 70 and the substrate holder 50 .

Since the encoder cover 12 is attached so as to contact 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 conductive metal such as aluminum. Therefore, by fitting the cylindrical portion 122 of the encoder cover 12 inside the annular wall 46 provided on the bearing holder 42 , the encoder cover 12 is electrically connected to the frame ground of the motor body 3 . By connecting the encoder 10 to the frame ground potential in this manner, the effect of shielding electromagnetic noise can be enhanced. Even if the cylindrical portion 122 of the encoder cover 12 is not fitted inside the annular wall 46, if the end face of the cylindrical portion 122 of the encoder cover 12 is fixed so as to contact 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 .
Alternatively, the encoder cover 12 may be fixed to the board unit 13 and electrically connected to the signal ground of the encoder circuit on the board 60 via the conductive fixing member 70 and the board holder 50 .

(encoder holder)
As shown in FIGS. 2 and 3, the encoder holder 14 has a trunk portion 142 in which a circular magnet placement hole 141 is formed, and a leg portion 143 protruding from the output side L1 end of the trunk portion 142 to the outer peripheral side. Prepare. As shown in FIG. 3 , the output-side L1 end surface of the leg portion 143 protrudes further toward the output side L1 than the output-side L1 end surface of the trunk portion 142 . The leg portions 143 are formed at three locations at equal angular intervals in the circumferential direction. The encoder holder 14 is positioned so that the rotation axis L of the encoder side rotary shaft 22 rotatably held at the center of the bearing holder 42 and the magnet arrangement hole 141 are arranged coaxially, and the plate 47 described above is positioned. It is positioned so as to place the legs 143 in notches 49 formed in the outer peripheral edge. As shown in FIG. 5 , the encoder holder 14 abuts on the bearing holder 42 via the legs 143 . The encoder holder 14 is fixed to the bearing holder 42 by screwing the legs 143 to the bottom surface of the circular recess 44 with fixing screws (not shown).

In the encoder holder 14, three fixing holes 144 for fixing the board unit 13 are formed in the end face of the body portion 142 on the counter-output side L2. The board unit 13 is positioned so as to abut against the end surface of the body portion 142 on the counter-output side L2, 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 board unit 13, the magnet 16 and the magnet holder 15. FIG. 6 is a view from the anti-output side L2, and FIG. 7 is a view 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 cylindrical fixing portion 152 projecting from the center of the magnet holding portion 151 toward the output side L1. The end of the encoder-side rotary shaft 22 is press-fitted or fixed to the fixing portion 152 by an adhesive. Alternatively, it is fixed by a set screw from a direction perpendicular to the output side L1. A shield wall 153 is provided between the magnet holding portion 151 and the fixed portion 152 . The magnets 16 include a first circular magnet 161 that fits into a recess formed in the center of the magnet holding portion 151, and a second annular magnet 162 that fits into a stepped portion formed on the outer periphery of the first magnet. Prepare. The first magnet 161 is magnetized with one N pole and one S pole in the circumferential direction. On the other hand, the second magnet 162 is magnetized with a plurality of N poles and S poles alternately arranged in the circumferential direction. The details of the configuration of the rotating body 18 composed of the encoder holder 14, the magnet 16, and the magnet holder 15 will be described later.

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 rotating 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 rotating shaft 22 is arranged in the center of the magnet placement hole 141 . The first magnet 161 and the second magnet 162 are arranged in the magnet arrangement hole 141 so as to face the anti-output side L2, and are coaxially arranged with the rotation axis L of the encoder-side rotation shaft 22 as the center.

(substrate unit)
As shown in FIGS. 6 and 7, the substrate unit 13 includes a substrate holder 50, a substrate 60 attached to the substrate holder 50, a magneto-sensitive element 17 mounted on the substrate 60, and the substrate 60 fixed to the substrate holder 50. and a shield member 80 attached to the substrate holder 50 from the output side L1. The substrate 60 has a substantially circular shape, and is provided with notches 61 obtained by notching two locations on the outer peripheral edge in a straight line. Further, the substrate 60 is formed with two fixing holes 62 for fixing to the substrate holder 50 . The two fixing holes 62 are arranged on opposite sides of the center of the substrate holder 50 . Also, one of the two fixing holes 62 is a ground through hole 621 electrically connected to the signal ground 5 (see FIG. 12) of the encoder circuit mounted on the substrate 60 . Either of the two fixing holes 62 may be used as the ground through hole 621 . Alternatively, three or more fixing holes 62 may be provided to fix the substrate 60 and the substrate holder 50 at three positions.

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 toward the counter-output side L2. The substrate holder 50 has a shape in which the end plate portion 53 is cut linearly at a portion overlapping the notch 61 of the substrate 60 in the direction of the rotation axis L, and the side plate portion 54 extends linearly. Two boss portions 51 corresponding to the fixing holes 62 of the substrate 60 are formed on the end plate portion 53 . 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 a spring pin as the fixing member 70, the substrate 60 is prevented from rattling with respect to the substrate holder 50. FIG. The fixing member 70 is made of a conductive metal such as SUS, and the substrate holder 50 is made of a conductive metal such as 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 5 of the encoder circuit mounted on the substrate 60 via the fixing member 70 and the ground through hole 621 . connected to

The substrate holder 50 is formed with bosses 52 at three locations corresponding to the fixing holes 144 of the encoder holder 14 for passing fixing screws (not shown). The boss portion 52 is connected to the side plate portion 54 . In this embodiment, the tip surface of the boss portion 52 serves as a contact surface that contacts the substrate 60 . Further, the substrate 60 is formed with fixing holes 63 for passing fixing screws at three locations corresponding to the boss portions 52 and the fixing holes 144 . Although not shown in FIG. 2, two positioning pins for positioning the board unit 13 protrude from the end surface of the trunk portion 142 on the counter-output side L2.

The board unit 13 is fixed to the encoder holder 14 by passing three fixing screws through the fixing hole 63 of the board 60 and the boss portion 52 of the board holder 50 and screwing the ends of the fixing screws into the fixing hole 144 . Further, since the leg portions 143 of the encoder holder 14 abut against the bearing holder 42 and are fixed, the board 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 holder 50 is insulated from the bearing holder 42 . However, a wiring pattern for frame grounding is prepared on the substrate 60, and in a state in which a metal member (not shown) is connected to the wiring pattern for frame grounding, one of the legs 143 of the encoder holder 14 and a screw are connected to the frame grounding wiring pattern. They are fastened together and electrically connected to the bearing holder 42 . Therefore, the wiring pattern for the frame ground is wired so as to be electrically connected to the shield of the encoder cable connected to the board unit 13, thereby suppressing noise on the cable.

The substrate 60 has 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. As shown in FIG. 6, on the counter-output side substrate surface 60a, there are mounted circuit elements (not shown) constituting an encoder circuit, a connector 65 for connecting an encoder cable, and the like. As shown in FIG. 7, the magneto-sensitive element 17 includes a first magneto-sensitive element 171 and a second magneto-sensitive element 172 arranged in the center of the output side substrate surface 60b. The first magneto-sensitive element 171 and the second magneto-sensitive element 172 respectively have ground terminals 6 and 7 (see FIG. 12) connected to the signal ground 5 of the encoder circuit constructed on the substrate 60 . Two hall elements 175 are mounted near the first magneto-sensitive element 171 on the output side substrate surface 60b. The two Hall elements 175 are arranged at angular positions separated by 90 degrees. The first magneto-sensitive element 171 , the second magneto-sensitive element 172 and the two hall elements 175 are all mounted on the substrate 60 .

In the substrate holder 50, a substantially rectangular through-hole (opening 58) is formed in the surface of the end plate portion 53 on the output side L1. The second magneto-sensitive element 172 is arranged in the opening 58 when the substrate 60 is fixed to the substrate holder 50 .

When the board unit 13 is fixed to the encoder holder 14, the first magneto-sensitive element 171 and the first magnet 161 face each other (see FIGS. 4 and 5). Also, the second magneto-sensitive element 172 arranged in the opening 58 of the substrate holder 50 faces the second magnet 162 . The encoder 10 has a predetermined gap between the surface of the output side L1 of the first magneto-sensitive element 171 and the first magnet 161 and between the surface of the output side L1 of the second magneto-sensitive element 172 and the second magnet 162. is formed.

The first magneto-sensitive element 171 and the two Hall elements 175 and the first magnet 161 arranged in the vicinity thereof discriminate the period of the output of the first magneto-sensitive element 171 obtained by one rotation by the two Hall elements 175. function as an absolute encoder. On the other hand, the second magneto-sensitive element 172 and the second magnet 162 function as an incremental encoder because they can obtain outputs of multiple cycles in one rotation. The encoder 10 can perform high-resolution and high-precision position detection by processing the outputs of these two sets of encoders.

(Shield member)
The shield member 80 is attached to the shield member attachment position 57 of the substrate holder 50 from the output side L1. The shield member 80 of this embodiment is a flexible sheet material and is sized to completely close the opening 58 . Although the shield member mounting position 57 in this embodiment is not formed, a step for mounting the shield member 80 may be provided at the shield member mounting position 57 . The shield member 80 contacts the shield mounting surface 59 facing the output side L1. The shield member 80, like the substrate holder 50, is made of a conductive non-magnetic metal such as aluminum. 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 5 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 second magneto-sensitive element 172 arranged in the opening 58 . By attaching the shield member 80 to the substrate holder 50, the first magneto-sensitive element 171 and the second magneto-sensitive element 172 are shielded from the motor body 3 by the signal ground potential members (the substrate holder 50 and the shield member 80). . Therefore, it is possible to effectively shield the frame ground noise and the power noise coming around through the gap between the first magnet 161 and the second magnet 162 . The first magneto-sensitive element 171 and the second magneto-sensitive element 172 face the first magnet 161 and the second magnet 162 through the shield member 80, but the shield member 80 and the substrate holder 50 are made of non-magnetic metal. Therefore, the function as a magnetic encoder can be maintained while shielding electromagnetic wave noise satisfactorily.

(Overview of layout of magnets and magneto-sensitive elements)
FIG. 8 shows the layout of the magnets 16 (the first magnet 161 and the second magnet 162), the magneto-sensitive elements 17 (the first magneto-sensitive element 171 and the second magneto-sensitive element 172), etc. in the encoder 10 of the present embodiment. FIG. 4 is a plan view showing a planar layout of magnets 16 and the like. 9 to 11 are explanatory diagrams showing the principle of the encoder 10 of this embodiment. FIG. 9 is an explanatory diagram of a signal processing system for the magneto-sensitive element 17, and FIG. FIG. 11 is an explanatory diagram showing the relationship between such a signal and the angular position θ (electrical angle) of the rotor 18 (magnet holder 15 and magnet 16). 8 and 9 schematically show the configuration of the magnet 16, the magneto-sensitive element 17, etc., and schematically show the magnetic poles of the second magnet 162 with a reduced number. In addition, the positional relationship between the magnetic resistance pattern of the second magneto-sensitive element 172 and the magnetic poles of the second magnet 162 is also shown schematically by shifting the positions of each other. It is formed in an extremely narrow range in the circumferential direction.

As shown in FIGS. 8 and 9, in the encoder 10 of the present embodiment, a magnetized surface 221 magnetized with one N pole and one S pole in the circumferential direction is provided on the rotating body 18 side along the axis of rotation. A first magnet 161 directed to the output side L1 in the direction L, and an annular magnet 161 in which a plurality of N poles and S poles are alternately magnetized in the circumferential direction at positions spaced apart from the first magnet 161 in the radial direction. A second magnet 162 that directs the magnetic surface 231 toward the output side L1 in the rotation axis direction L is held. The first magnet 161 and the second magnet 162 rotate together with the rotor 18 around the rotation axis. Although shown in a simplified manner in FIGS. 8 and 9, the second magnet 162 of the present embodiment has 32 magnetic pole pairs of N and S poles in the circumferential direction. provided in pairs.

In this embodiment, the first magnet 161 is a disk-shaped permanent magnet. The second magnet 162 has a cylindrical shape and is arranged at a position spaced apart from the first magnet 161 in the radial direction. The first magnet 161 and the second magnet 162 are made of bond magnets or the like. In this embodiment, for example, a sintered ferrite magnet is used. In this embodiment, on the magnetized surface 231 of the second magnet 162, a plurality of tracks 310 magnetized in multiple poles alternately having N and S poles in the circumferential direction are arranged in parallel in the radial direction. In this embodiment, two rows of tracks 310 are formed. The positions of the north pole and the south pole are shifted in the circumferential direction between the two tracks 310 , and in this embodiment, the north pole and the south pole are shifted by one pole in the circumferential direction between the two tracks 310 .

The substrate unit 13 includes a first magneto-sensitive element 171 that faces the magnetized surface 221 of the first magnet 161 on the output side L1 in the rotation axis direction L, and a magneto-sensitive element 171 that rotates with respect to the magnetized surface 231 of the second magnet 162 . A second magneto-sensitive element 172 is provided facing the output side L1 in the axial direction L. In this embodiment, both the first magneto-sensitive element 171 and the second magneto-sensitive element 172 are held on the output side substrate surface 60b on the output side L1 of the substrate 60 in the rotational axis direction L, as shown in FIG. It is

Also, on the substrate 60, a first Hall element 175a and a second Hall element 175a are positioned at a position facing the first magnet 161, and a second Hall element 175a is positioned at a position shifted by 90 degrees in the mechanical angle in the circumferential direction with respect to the first Hall element 175a. 175b are provided. In this embodiment, both the first Hall element 175a and the second Hall element 175b are held on the output side substrate surface 60b of the substrate 60, and face the first magnet 161 on the output side L1 in the rotation axis direction L. ing.

As shown in FIGS. 8 and 9, the first magneto-sensitive element 171 has a phase A (SIN) magnetoresistive pattern and a B phase (COS ) magnetoresistive pattern. In the first magneto-sensitive element 171, the A-phase magnetoresistive pattern includes the +a-phase (SIN+) magnetoresistive pattern 243 and the -a-phase (SIN-) magnetoresistive pattern 243 for detecting the movement of the rotating body 18 with a phase difference of 180°. The B-phase magnetoresistive pattern 241 is a +b-phase (COS+) magnetoresistive pattern 244 and a -b-phase (COS-) magnetoresistive pattern 244 for detecting the movement of the rotating body 18 with a phase difference of 180°. A magnetoresistive pattern 242 is provided.

Here, the +a-phase magnetoresistive pattern 243 and the −a-phase magnetoresistive pattern 241 form a bridge circuit, one end of which is connected to the power supply terminal (Vcc) and the other end of which is connected to the ground terminal (GND). It is connected. A terminal (+a) for outputting the +a phase is provided at the midpoint position of the +a phase magnetoresistive pattern 243, and the -a phase is output at the midpoint position of the -a phase magnetoresistive pattern 241. A terminal (-a) is provided. In addition, the +b-phase magnetoresistive pattern 244 and the −b-phase magnetoresistive pattern 242 also form a bridge circuit like the +a-phase magnetoresistive pattern 244 and the −a-phase magnetoresistive pattern 241. It is connected to a power supply terminal (Vcc) and the other end is connected to a ground terminal (GND). A terminal (+b) for outputting the +b phase is provided at the midpoint position of the +b phase magnetoresistive pattern 244, and the -b phase is output at the midpoint position of the -b phase magnetoresistive pattern 242. A terminal (-b) is provided.

The second magneto-sensitive element 172 has an A-phase (SIN) magnetoresistive pattern and a B-phase (COS) magnetoresistive pattern having a phase difference of 90° with respect to the phase of the second magnet 162 . 2 magnetoresistive elements. In the second magneto-sensitive element 172, the A-phase magnetoresistive pattern includes the +a-phase (SIN+) magnetoresistive pattern 264 and the -a-phase (SIN-) magnetoresistive pattern 264 for detecting the movement of the rotating body 18 with a phase difference of 180°. The B-phase magnetoresistive pattern 262 is a +b-phase (COS+) magnetoresistive pattern 263 and a -b-phase (COS-) magnetoresistive pattern 263 for detecting the movement of the rotating body 18 with a phase difference of 180°. A magnetoresistive pattern 261 is provided.

Here, the +a-phase magnetoresistive pattern 264 and the −a-phase magnetoresistive pattern 262 form a bridge circuit like the first magneto-sensitive element 171, one end of which is connected to the power supply terminal (Vcc), The other end is connected to the ground terminal (GND). A terminal (+a) for outputting the +a phase is provided at the midpoint position of the +a phase magnetoresistive pattern 264, and the -a phase is output at the midpoint position of the -a phase magnetoresistive pattern 262. A terminal (-a) is provided. The +b-phase magnetoresistive pattern 263 and the −b-phase magnetoresistive pattern 261 form a bridge circuit, like the +a-phase magnetoresistive pattern 264 and the −a-phase magnetoresistive pattern 262. It is connected to a power supply terminal (Vcc) and the other end is connected to a ground terminal (GND). A terminal (+b) for outputting the +b phase is provided at the midpoint position of the +b phase magnetoresistive pattern 263, and the -b phase is output at the midpoint position of the -b phase magnetoresistive pattern 261. A terminal (-b) is provided.

8 and 9, the second magneto-sensitive element 172 having such a configuration is arranged at a position overlapping the boundary portion of the adjacent tracks 310 in the rotation axis direction L in the second magnet 162. As shown in FIGS. Therefore, the magnetoresistive patterns 261 to 264 of the second magneto-sensitive element 172 rotate in such a manner that the orientation changes in the in-plane direction of the track 310 at a magnetic field intensity higher than the saturation sensitivity region of the resistance value of each of the magnetoresistive patterns 261 to 264. A magnetic field can be detected. That is, since the second magnet 162 has a plurality of tracks 310, the boundary lines between adjacent tracks 310 have a magnetic field intensity higher than the saturated sensitivity region of the resistance values of the magnetoresistive patterns 261-264. A rotating magnetic field is generated in which the orientation of the in-plane direction changes. Here, the saturated sensitivity region generally refers to a region other than the region where the amount of change in the resistance value k can be expressed approximately with the magnetic field strength H by the formula “k∝H2”. Further, the principle for detecting the direction of the rotating magnetic field (rotation of the magnetic vector) at a magnetic field strength above the saturation sensitivity region is that the resistance value is When a magnetic field intensity to saturate is applied, between the angle θ formed by the magnetic field and the current direction and the resistance value R of each of the magnetoresistive patterns 261 to 264, the following formula R=R0−k×sin2θ
R0: Resistance value in no magnetic field
k: Amount of change in resistance value (constant when over the saturation sensitivity region)
It utilizes the fact that there is a relationship shown by If the rotating magnetic field is detected based on such a principle, the resistance value R changes along a sine wave when the angle θ changes, so that A phase and B phase with high waveform quality can be obtained.

In the encoder 10 having such a configuration, the first magneto-sensitive element 171, the first Hall element 175a, the second Hall element 175b, and the second magneto-sensitive element 172 are provided with amplifier circuits 291 to 296, and these amplifier circuits 291 to 296. A CPU 290 (arithmetic circuit) and the like for performing interpolation processing and various arithmetic processing on the sine wave signals sin and cos output from the first magneto-sensitive element 171, the first hall element 175a, the second hall element 175b, and the output from the second magneto-sensitive element 172, the rotational angular position of the rotor 18 with respect to the board unit 13 is obtained.

More specifically, when the rotor 18 rotates once in the encoder 10, the first magneto-sensitive element 171 outputs two cycles of the sine wave signals sin and cos shown in FIG. Therefore, after the sine wave signals sin and cos are amplified by the amplifier circuits 291 and 292, the CPU 290 obtains θ=tan−1 (sin/cos) from the sine wave signals sin and cos as shown in FIG. , the angular position .theta. of the rotation output shaft can be obtained. In addition, in this embodiment, the first Hall element 175a and the second Hall element 175b are arranged at positions shifted by 90° from the center of the first magnet 161 . Therefore, it can be known in which section of the sine wave signal sin or cos the current position is located. Therefore, the encoder 10 provides first absolute angular position information of the rotating body 18 based on the detection result of the first magneto-sensitive element 171, the detection result of the first Hall element 175a, and the detection result of the second Hall element 175b. can be generated and an absolute operation can be performed.

In the encoder 10 of the present embodiment, the second magnet 162 is provided with an annular magnetized surface 231 in which a plurality of N poles and S poles are alternately magnetized in the circumferential direction. A second magneto-sensitive element 172 facing 162 outputs sinusoidal signals sin, cos as shown in FIG. Therefore, if the sine wave signals sin and cos output from the second magneto-sensitive element 172 are amplified by the amplifier circuits 293 and 294 and then converted into pulse signals or the like in the CPU 290, the signals correspond to the magnetic poles of the second magnet 162. A signal is obtained. Therefore, in the CPU 290, the first absolute angle of the rotor 18 is obtained based on the detection result of the first magneto-sensitive element 171, the detection result of the first Hall element 175a, and the detection result of the second Hall element 175b. By using the position information and the detection result of the second magneto-sensitive element 172, the second absolute angular position information of the rotor 18 can be obtained, and the second absolute angular position information is the same as the first absolute angular position information. Higher resolution than . That is, the first absolute angular position information of the rotating body 18 is detected based on the detection result of the first magneto-sensitive element 171, the detection result of the first Hall element 175a, and the detection result of the second Hall element 175b, Using the first absolute angular position information and the detection result of the second magneto-sensitive element 172, the absolute angular position (second absolute angular position information) of the rotating body 18 with higher precision is obtained.

(Arrangement of magnets and magneto-sensitive elements in the direction of the rotation axis)
Next, referring to FIG. 12, which is a schematic view showing the layout of the encoder 10 of the present embodiment from the side, the magnet 16 (first magnet 161 and second magnet 162) and the magneto-sensitive element 17 ( The arrangement of the first magneto-sensitive element 171 and the second magneto-sensitive element 172) will be described. Note that FIG. 12 is a schematic diagram, and most of the constituent members other than the magnet 16 and the magneto-sensitive element 17 are omitted.

As shown in FIG. 12, the length on the output side L1 in the rotational axis direction L from the output-side substrate surface 60b of the second magneto-sensitive element 172 is the length from the output-side substrate surface 60b of the first magneto-sensitive element 171 to It is longer than the length on the output side L1 in the rotation axis direction L. In other words, the second magneto-sensitive element 172 protrudes toward the output side L1, which is closer to the magnet than the first magneto-sensitive element 171, in the direction L of the rotation axis. Therefore, the space between the second magneto-sensitive element 172 and the second magnet 162, which is required to be narrow because the number of magnetizations is large and the magnetic flux does not reach far, can be easily narrowed. Further, since both the first magneto-sensitive element 171 and the second magneto-sensitive element 172 are mounted on the substrate 60, the substrate unit 13 can be easily assembled. Therefore, the motor 1 of this embodiment can be easily formed and has high magnetic detection sensitivity. The first magneto-sensitive element 171 and the second magneto-sensitive element 172 are preferably mounted on the substrate 60 by resin molding or flip-chip mounted on the substrate 60 .

As shown in FIG. 12, the distance between the first magneto-sensitive element 171 and the first magnet 161 is wider than the distance between the second magneto-sensitive element 172 and the second magnet 162 . The second magnet 162 has a greater number of magnetizations than the first magnet 161, and the magnetic flux does not reach as far as the first magnet 161. By making the distance from the magnet 162 narrower than the distance between the first magneto-sensitive element 171 and the first magnet 161, both the first magneto-sensitive element 171 and the second magneto-sensitive element 172 can detect magnetism with high sensitivity. becomes possible.

Further, as described above, the substrate 60 has the signal ground 5 connected to the ground terminals 6 and 7 of the first magneto-sensitive element 171 and the second magneto-sensitive element 172, and the substrate holder 50 is connected to the rotation axis. An opening 58 is provided at the position of the second magneto-sensitive element 172 as seen from the direction L. As shown in FIG. Further, as shown in FIG. 12 , the opening 58 is covered with a shield member 80 that is thinner than the substrate holder 50 in the rotation axis direction L. As shown in FIG. As described above, the substrate holder 50 and the shield member 80 are both made of a conductive member (conductive metal) and connected to the signal ground 5 . By shielding the second magneto-sensitive element 172 with the thin shield member 80 in this manner, the distance between the second magneto-sensitive element 172 and the second magnet 162 is kept narrow, while the second magneto-sensitive element 172 is exposed to the magnet 16 side. Intrusion of noise (frame ground noise, power supply noise, etc.) from the magnetic field can be suppressed from affecting magnetic detection results. Further, by making the shield member 80 a separate member from the substrate holder 50, the shield effect can be easily adjusted.

Further, as shown in FIG. 12, the position of the first magneto-sensitive element 171 facing the first magnet 161 is covered with the substrate holder 50 . With such a configuration, the motor 1 of the present embodiment prevents noise from entering the first magneto-sensitive element 171 from the magnet 16 side and affecting the magnetism detection result.

In this embodiment, no opening is provided at the position of the first magneto-sensitive element 171, and since there is no opening, the position of the first magneto-sensitive element 171 is not covered with the shield member 80. , an opening may be provided at the position of the first magneto-sensitive element 171, and a shield member 80 covering the opening may be provided. In such a configuration, the opening at the position of the first magneto-sensitive element 171 and the opening 58 at the position of the second magneto-sensitive element 172 may be covered with one shield member 80 .

Here, it is preferable that the second magneto-sensitive element 172 does not protrude beyond the substrate holder 50 toward the second magnet 162 . This is because the second magneto-sensitive element 172 can be prevented from coming into contact with other members. Further, when the shield member 80 is attached to the substrate holder 50, the shield member 80 can be easily attached without being deformed. In this embodiment, the surface of the second magneto-sensitive element 172 on the side of the second magnet 162 is substantially flush with the surface of the substrate holder 50 on the side of the second magnet 162 (more precisely, the shield mounting surface 59). .

Further, as shown in FIG. 12, the second magneto-sensitive element 172 of this embodiment has a magneto-sensitive film 172a. The magneto-sensitive film 172a is arranged on the second magneto-sensitive element 172 in the rotational axis direction L on the side of the second magnet 162 (near the output side L1). That is, the position of the magneto-sensitive film 172a on the second magneto-sensitive element 172 in the rotational axis direction L is closer to the second magnet 162 than the center of the second magneto-sensitive element 172 in the rotational axis direction L. In this way, by bringing the position of the magnetosensitive film 172a close to the magnet 16, it is possible to detect magnetism with particularly high sensitivity.

In the motor 1 of the present embodiment, as shown in FIGS. 6 and 8, the second magnet 162 is arranged around the first magnet 161, and the first magnet 161 and the second magnet 162 are arranged. Between them, a shield wall 153 is provided over the entire circumference. The shield wall 153 is integrally formed with the magnet holding portion 151 and the fixing portion 152 and suppresses the influence of magnetic flux directed from the first magnet 161 to the second magnet 162 . Here, it is preferable that the shield wall 153 does not protrude toward the substrate 60 beyond the second magnet 162 as in the motor 1 of the present embodiment shown in FIG. By providing the shield wall 153 not exceeding the second magnet 162 between the first magnet 161 and the second magnet 162, the influence of the magnetic flux directed from the first magnet 161 to the second magnet 162 is suppressed, and the second magnet This is because it is possible to prevent the magnetic flux of 162 from heading toward the shield wall 153 and the magnetic flux toward the second magneto-sensitive element 172 from weakening. In this embodiment, the surface of the shield wall 153 and the surface of the second magnet 162 on the non-output side L2 are flush with each other, but the surface of the second magnet 162 on the non-output side L2 It may protrude from the surface of the side L2 to the counter-output side L2.

Moreover, it is preferable that the shield wall 153 protrude beyond the first magnet 161 toward the counter-output side L2, which is the substrate 60 side, as in the motor 1 of the present embodiment shown in FIG. This is because the influence of the magnetic flux from the first magnet 161 toward the second magnet 162 can be suppressed by the shield wall 153 projecting beyond the first magnet 161 toward the counter-output side L2.

The second magnet 162 may be magnetized in advance and fixed to the magnet holder 15 , but it is more preferable that the second magnet 162 is magnetized while being fixed to the magnet holder 15 . This is because the deviation of the center of the second magnet 162 with respect to the rotating shaft 2 (the encoder-side rotating shaft 22) can be suppressed. Here, in order to improve magnetization, it is preferable that the shield wall 153 does not protrude beyond the second magnet 162 in the rotation axis direction L as in the present embodiment. In addition, although the second magnet 162 is misaligned with respect to the magnet holder 15 , the second magnet 162 is fixed to the magnet holder 15 without any deviation of the center of the second magnet 162 with respect to the rotating shaft 2 . It can be determined that it is magnetized.

The present invention is not limited to the above-described embodiments, and can be implemented in various configurations without departing from the spirit of the present invention. For example, the technical features in the examples corresponding to the technical features in the respective modes described in the Summary of the Invention are used to solve some or all of the above problems, or Substitutions and combinations may be made as appropriate to achieve part or all.
Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 1... Motor, 2... Rotating shaft, 3... Motor body, 4... Motor case, 5... Signal ground, 6... Ground terminal, 7... Ground terminal, 10... Encoder, 11... Outer case, 12... Encoder cover, 13... Substrate unit 14 Encoder holder 15 Magnet holder 16 Magnet 17 Magneto-sensitive element 18 Rotating body 21 Motor-side rotating shaft 22 Encoder-side rotating shaft 41 Cylindrical case 42 Bearing holder 43 Bearing 44 Circular concave portion 45 Flange 46 Annular wall 47 Plate 48 Through hole 49 Notch 50 Substrate holder 51 Boss portion 52 Boss portion 53 End plate portion 54 Side plate portion 57 Shield member mounting position 58 Opening (through hole) 59 Shield mounting surface 60 Substrate 60a Non-output substrate surface 60b Output substrate Surface 61 Notch 62 Fixing hole 63 Fixing hole 65 Connector 70 Fixing member 80 Shield member 111 End plate portion 112 Side plate portion 113 Notch 114 Seal Member 121 End plate 122 Cylindrical part 123 Notch 141 Magnet placement hole 142 Body 143 Leg 144 Fixing hole 151 Magnet holding part 152 Fixing part , 153... Shield wall 161... First magnet 162... Second magnet 171... First magneto-sensitive element 172... Second magneto-sensitive element 172a... Magneto-sensitive film 175... Hall element 175a... First Hall Elements 175b...Second Hall element 221...Magnetized surface 231...Magnetized surface 241...Magnetic resistance pattern 242...Magnetic resistance pattern 243...Magnetic resistance pattern 244...Magnetic resistance pattern 261...Magnetic resistance pattern , 262... Magnetoresistance pattern 263... Magnetoresistance pattern 264... Magnetoresistance pattern 290... CPU 291... Amplifier circuit 292... Amplifier circuit 293... Amplifier circuit 294... Amplifier circuit 295... Amplifier circuit 296... Amplifier circuit 310 Track 621 Ground through hole L Rotational axis L1 Output side L2 Anti-output side

Claims (7)

A first magnet magnetized with one N pole and one S pole, and a second magnet magnetized with a plurality of N poles and S poles, wherein the first magnet and the second magnet a magnet holder rotatable with both magnets;
A first magneto-sensitive element provided facing the first magnet in the rotation axis direction of the magnet holder and a second magneto-sensitive element provided facing the second magnet in the rotation axis direction are mounted. and
with
The second magneto-sensitive element protrudes toward the magnet side more than the first magneto-sensitive element ,
A substrate holder that covers the substrate on the magnet side in the rotation axis direction,
The substrate has a signal ground connected to the ground terminals of the first magneto-sensitive element and the second magneto-sensitive element,
The substrate holder has an opening at a position of the second magneto-sensitive element when viewed from the rotation axis direction,
The opening is covered with a shield member having a thickness in the direction of the rotation axis that is thinner than the thickness of the substrate holder,
The substrate holder and the shield member are both formed of a conductive member and connected to the signal ground,
A motor according to claim 1, wherein a position of said first magneto-sensitive element facing said first magnet is covered with said substrate holder . 2. The motor of claim 1 , wherein
A motor according to claim 1, wherein the second magneto-sensitive element does not protrude beyond the substrate holder toward the second magnet. 3. The motor according to claim 1 or 2 ,
A motor according to claim 1, wherein the distance between said second magneto-sensitive element and said second magnet is narrower than the distance between said first magneto-sensitive element and said first magnet. In the motor according to any one of claims 1 to 3 ,
The second magneto-sensitive element has a magneto-sensitive film,
A motor according to claim 1, wherein a position of said magneto-sensitive film in said second magneto-sensitive element in said rotational axis direction is closer to said second magnet than a center of said second magneto-sensitive element in said rotational axis direction. In the motor according to any one of claims 1 to 4 ,
The second magnet is arranged around the first magnet,
A shield wall is provided along the entire circumference between the first magnet and the second magnet,
The motor according to claim 1, wherein the shield wall does not protrude toward the substrate beyond the second magnet. A motor according to claim 5 , wherein
The motor according to claim 1, wherein the shield wall protrudes toward the substrate beyond the first magnet. In the motor according to any one of claims 1 to 6 ,
A motor, wherein the second magnet is magnetized while being fixed to the magnet holder.

Images