Encoder and motor with encoder

Abstract

To suppress component cost without lowering the performance of an encoder and suppress the effect of heat generation from a motor.SOLUTION: A motor 1 with an encoder comprises an encoder 10 and a motor 3 provided with a revolving shaft 2. The encoder 10 includes a magnet 14 that rotates integrally with the revolving shaft 2 and a circuit board 13 on which a magnet-sensitive element 17 is located facing the magnet 14. The encoder 10 also includes a cover 12 that covers the circuit board 13 from the side opposite the magnet 14 and an encoder case 11 for accommodating the magnet 14 and the circuit board 13, to the inner surface of which the cover 12 is secured. The encoder case 11 includes a seat surface 50 to which the cover 12 is secured, and a circuit board fixing part 52 which projects from an opening 61 of the cover 12 to the inside of the cover 12, with the circuit board 13 secured to the circuit board fixing part 52.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to an encoder and a motor with an encoder.

Background Art

[0002] Patent Document 1 discloses a motor with an encoder in which an encoder is disposed at an end of the motor. The encoder of Patent Document 1 includes a magnet that rotates integrally with a rotating shaft protruding from a bearing holder disposed at an end of a motor case, and a substrate facing the magnet. A magnetic sensing element for detecting the rotation of the magnet is disposed on the substrate. The magnet and the substrate are housed in an encoder case fixed to an end of the motor case. An encoder holder surrounding the periphery of the magnet is disposed inside the encoder case, and the substrate is fixed to the encoder holder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, in order to ensure encoder performance, it has been required to improve the positional accuracy of the substrate with respect to the magnet. In a configuration where the substrate is fixed to the encoder holder as in Patent Document 1, in order to improve the positional accuracy of the substrate, high dimensional accuracy is required for the encoder holder. Further, in order to improve the positional accuracy of the encoder holder, high dimensional accuracy is also required for motor side components (bearing holder in Patent Document 1) to which the encoder holder is fixed. Therefore, there is a problem that cost reduction is difficult.

[0005] Further, in a structure in which the substrate is fixed to the encoder holder, heat generated by the motor is transmitted to the substrate through the encoder holder. Therefore, there is a problem that it is easily affected by heat generated by the motor.

[0006] In view of the above problems, an object of the present invention is to suppress component costs without degrading the performance of the encoder and to suppress the influence of the heat generation of the motor.

Means for Solving the Problems

[0007] In order to solve the above problems, the encoder of the present invention includes a magnet that rotates integrally with a rotating shaft, a substrate on which a magnetosensitive element facing the magnet is disposed, a cover that covers the substrate from the side opposite to the magnet, and an encoder case that houses the magnet and the substrate and has the cover fixed to an inner surface thereof. The encoder case includes a substrate fixing portion disposed inside the cover, and the substrate is fixed to the substrate fixing portion.

[0008] According to the present invention, the substrate of the encoder is fixed to a substrate fixing portion provided in the encoder case. Therefore, since an encoder holder fixed to a component on the motor side is not required, the number of components can be reduced. In addition, in order to ensure the encoder accuracy, instead of increasing the positional accuracy between the substrate and the magnet, the output of the encoder may be measured after the encoder is assembled and the output may be corrected so as to obtain the required encoder accuracy. Therefore, since an encoder holder is not required and the dimensional accuracy of other components does not need to be increased, component costs can be suppressed without degrading the performance of the encoder. Furthermore, since an encoder holder that serves as a heat transfer path between the substrate and the motor is not interposed, and the encoder case to which the substrate is fixed is in contact with the outside air, heat transmitted from the motor is easily dissipated. Therefore, the influence of the heat generation of the motor on the encoder can be suppressed.

[0009] In the present invention, the encoder case includes a case end plate portion provided with a seating surface against which the cover abuts, and a case side plate portion extending from the outer peripheral edge of the case end plate portion toward the magnet side. The seating surface is provided with a recess recessed toward the side opposite to the cover. The substrate fixing portion is provided inside the recess. The tip of the substrate fixing portion is located closer to the magnet side than the seating surface. The cover includes an opening in which the substrate fixing portion is disposed, and the opening is preferably located inside the recess. In this way, when assembling the encoder, the cover and the substrate can be assembled to the encoder case from the same direction, so the assembly work is easy. Further, since the edge of the opening of the cover does not abut against the seating surface, it is possible to avoid the burrs formed on the edge of the opening during the manufacture of the cover from hitting the seating surface and reducing the position accuracy of the cover.

[0010] In the present invention, the cover is made of a magnetic member having conductivity. The cover includes a cover end plate portion that abuts against the seating surface, and a cover side plate portion that extends from the outer peripheral edge of the cover end plate portion toward the magnet side and surrounds the outer peripheral side of the substrate. The cover end plate portion preferably includes a fixing hole into which a conductive fixing member protruding from the substrate is fitted. In this way, the cover can function as a shield against magnetic noise such as external magnetic fields and electrical noise. Further, since the substrate and the cover are electrically connected by the conductive fixing member, the signal ground of the encoder circuit on the substrate and the cover can be electrically connected. Therefore, since the cover functions as a shield of the signal ground potential, the influence of frame ground noise and power supply noise on the substrate can be reduced.

[0011] In the present invention, the substrate fixing portions are provided at a plurality of positions spaced apart in the circumferential direction with respect to the central axis of the rotating shaft in the encoder case, and each of the plurality of substrate fixing portions preferably abuts against the outer peripheral portion of the substrate. In this way, the outer peripheral portion of the substrate can be supported at a plurality of positions, so that the inclination of the substrate can be suppressed.

[0012] In the present invention, at least one of the plurality of substrate fixing portions is provided with a positioning convex portion, and the substrate preferably includes a positioning hole into which the positioning convex portion fits. By doing so, the substrate can be directly positioned with respect to the encoder case, so that the positional accuracy of the substrate can be improved.

[0013] Next, the motor with an encoder according to the present invention is characterized by having the above-described encoder and a motor having the rotation shaft.

[0014] In the present invention, the motor preferably includes a motor case to which the encoder case is fixed and a sealing material interposed between the encoder case and the motor case. By assembling with the sealing material interposed between the encoder case and the motor case in this way, it becomes difficult for the heat of the motor to be transmitted to the encoder case. Therefore, the influence of the heat generation of the motor on the encoder can be reduced.

[0015] Alternatively, the motor with an encoder according to the present invention has a motor having a rotation shaft and an encoder that detects the rotation of the rotation shaft. The encoder includes a magnet that rotates integrally with the rotation shaft, a substrate on which a magnetic sensing element facing the magnet is disposed, and an encoder case that houses the magnet and the substrate. The substrate is fixed to a substrate fixing portion provided on the inner surface of the encoder case, and the motor includes a motor case to which the encoder case is fixed and a sealing material interposed between the encoder case and the motor case.

[0016] In the present invention, one of the encoder case and the motor case is where the sealing material is It is preferable to include a sealing material placement surface to be configured, and a butting portion that protrudes to the other side of the encoder case and the motor case from the sealing material placement surface and abuts against the other side. By doing so, for example, the encoder case can be positioned in the height direction (central axis direction) by the butting portion that manages the height dimension in the central axis direction with respect to the substrate fixing portion. Therefore, the positional accuracy of the substrate fixed to the encoder case in the height direction (central axis direction) can be improved. Further, since only the butting portion abuts between the encoder case and the motor case and a sealing material is interposed in other portions, heat of the motor is less likely to be transmitted to the encoder case.

[0017] In the present invention, it is preferable that the encoder case includes a sealing material placement surface on which the sealing material is arranged, and a portion excluding the sealing material placement surface is separated from the motor case. By doing so, since the encoder case and the motor case are not in direct contact, heat of the motor is less likely to be transmitted to the encoder case.

[0018] In the present invention, it has an encoder cable connected to a connector arranged on the substrate, the encoder cable includes a signal line connected to a wiring pattern provided on the substrate, and a frame ground line insulated from the signal line, and it is preferable that the frame ground line is fixed to the motor case via a conductive screw. By doing so, since the encoder cable can be connected to the motor case at the frame ground potential, electrical noise generated from the encoder cable can be reduced. Therefore, the influence of electrical noise generated from the encoder cable on the substrate can be suppressed.

Effects of the Invention

[0019] According to the present invention, the substrate of the encoder is fixed to a substrate fixing portion provided in the encoder case. Therefore, since an encoder holder fixed to the motor side parts is not required, the number of parts can be reduced. Further, in order to ensure the encoder accuracy, instead of increasing the positional accuracy between the substrate and the magnet, after assembling the encoder, the output of the encoder may be measured and the output may be corrected so that the required encoder accuracy can be obtained. Therefore, since an encoder holder is not required and it is not necessary to increase the dimensional accuracy of other parts, the component cost can be suppressed without degrading the performance of the encoder. Furthermore, since there is no encoder holder serving as a heat transfer path between the substrate and the motor, and the encoder case to which the substrate is fixed is in contact with the outside air, it is easy to dissipate the heat transmitted from the motor. Therefore, the influence of the heat generation of the motor on the encoder can be suppressed.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0021] Hereinafter, with reference to the drawings, embodiments of an encoder and a motor with an encoder to which the present invention is applied will be described. FIG. 1 is an external perspective view of a motor 1 with an encoder 10 to which the present invention is applied. FIG. 2 is a cross-sectional view of the motor 1 with an encoder in FIG. 1. FIG. 3 is an exploded perspective view of the encoder 10 as viewed from the L2 side. FIG. 4 is an exploded perspective view of the encoder case 11, the cover 12, and the substrate 13 as viewed from the L1 side. FIG. 5 is a plan view of the encoder case 11 as viewed from the inside (L1 side). FIGS. 6 and 7 are explanatory views showing a method of assembling the encoder case 11, the cover 12, and the substrate 13. FIG. 6 is a plan view of the assembled encoder case 11 and cover 12 as viewed from the L1 side, and FIG. 7 is a plan view of the assembled encoder case 11, cover 12, and substrate 13 as viewed from the L1 side. FIG. 8 is a cross-sectional view (a cross-sectional view taken at the A-A position in FIG. 5) of the encoder case 11, the cover 12, and the substrate 13 cut at the positions of the substrate fixing portion 52 and the seating surface 50.

[0022] The motor 1 with an encoder includes a motor 3 having a rotating shaft 2 and an encoder 10 for detecting the rotation of the rotating shaft 2. In this specification, the three directions of X, Y, and Z are directions perpendicular to each other. One side of these three directions is respectively X1, Y1, Z1, and the other side is respectively X2, Y2, Z2. The Z direction is parallel to the central axis L of the rotating shaft 2, and the X direction and the Y direction are perpendicular to the central axis L.

[0023] (Motor) The motor 3 includes a motor case 4 that houses a rotor and a stator (not shown). The rotor rotates integrally with the rotating shaft 2, and the stator is fixed to the motor case 4. A driven member is connected to the end of the rotating shaft 2 that protrudes from the motor case 4 to the outside. In this specification, the direction in which the rotating shaft 2 protrudes from the motor case 4 is defined as the output side L1, and the opposite side of the output side L1 is defined as the anti-output side L2. The encoder 10 is fixed to the end of the motor 3 on the anti-output side L2.

[0024] As shown in Fig. 1, the motor case 4 includes a cylindrical case 41 extending in the direction of the central axis L, and a bearing holder 42 fixed to the end of the cylindrical case 41 on the opposite output side L2. The encoder 10 is fixed to the bearing holder 42 from the opposite output side L2. As shown in Figs. 2 and 3, the bearing holder 42 includes a circular recess 44 recessed on the output side L1, a flange 45 extending to the outer peripheral side of the circular recess 44, and an annular wall 46 protruding toward the opposite output side L2 along the edge of the circular recess 44. As shown in Fig. 3, a plurality of fixing holes 451 are provided on the flange 45 on the outer peripheral side of the annular wall 46.

[0025] As shown in Fig. 2, a bearing 43 is held at the center of the bottom of the circular recess 44. The bearing 43 rotatably supports the end of the rotating shaft 2 on the opposite output side L2. Also, 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 opposite output side L2. The rotating shaft 2 is passed through a through hole provided at the center of the plate 47 and supported by the bearing 43. As shown in Fig. 3, protruding portions 471 protruding toward the outer peripheral side are formed at three equiangular intervals on the outer peripheral edge of the plate 47. The protruding portions 471 are arranged in notch portions 461 provided in the annular wall 46 of the bearing holder 42. The plate 47 is fixed to the bearing holder 42 by screws (not shown) for each protruding portion 471.

[0026] (Encoder) As shown in Figs. 2 and 3, the encoder 10 includes an encoder case 11 fixed to the bearing holder 42, a cover 12 disposed inside the encoder case 11, and a substrate 13 disposed inside the cover 12. The encoder 10 also includes a magnet 14 facing the substrate 13 and a magnet holder 15 holding the magnet 14.

[0027] The magnet holder 15 is fixed to the tip of the rotating shaft 2 on the opposite output side L2. The magnet holder 15 is made of a magnetic material. As shown in Fig. 2, the magnet holder 15 includes a substantially disc-shaped magnet holding portion 151 and a cylindrical shaft portion 152 protruding from the center of the magnet holding portion 151 toward the output side L1. The shaft portion 15 At 2, the tip of the rotating shaft 2 is fixed by any one of press fitting, an adhesive, and a set screw, or a combination thereof. In this embodiment, a set screw 154 is screwed into a screw hole penetrating the shaft portion 152 in the radial direction.

[0028] The magnet 14 is fixed to the surface of the magnet holding portion 151 on the opposite output side L2, and is surrounded by a shield portion 153 protruding from the outer peripheral edge of the magnet holding portion 151 to the opposite output side L2. The magnet 14 is magnetized with N poles and S poles one by one in the circumferential direction and rotates integrally with the rotating shaft 2. The substrate 13 includes a magnetosensitive element 17 facing the magnet 14. The signal of the magnetosensitive element 17 is input to an encoder circuit on the substrate 13. As the magnetosensitive element 17, for example, an MR element is used.

[0029] (Encoder case) As shown in FIGS. 1 and 3, the encoder case 11 includes a case end plate portion 111 that is substantially rectangular when viewed in the direction of the central axis L, and a cylindrical case side plate portion 112 that extends from the outer peripheral edge of the case end plate portion 111 to the output side L1. A wiring extraction portion 113 for passing the encoder cable 5 is provided on the side surface of the case side plate portion 112 facing the X1 side.

[0030] As shown in FIG. 2, the encoder case 11 and the bearing holder 42 are fixed by interposing a sealing material 48 between the end face of the output side L1 of the case side plate portion 112 and the outer peripheral edge of the flange 45 of the bearing holder 42 and tightening fixing screws (not shown) at four corners. The encoder case 11 and the motor case 4 are made of a resin molded member or a non-magnetic material such as aluminum.

[0031] In this embodiment, the encoder case 11 includes an abutting portion 114 that abuts against the motor case 4 on the outer peripheral side of the sealing material 48. As shown in FIG. 4, the end surface of the output side L1 of the case side plate portion 112 includes a flat sealing material placement surface 115 that surrounds the internal space of the encoder case 11 on all sides, and an abutting portion 114 that protrudes toward the output side L1 from the sealing material placement surface 115. The abutting portion 114 is provided on the outer peripheral side of the sealing material placement surface 115 and is arranged at four locations near the corners of the encoder case 11. Further, the sealing material placement surface 115 is provided with positioning convex portions 116 that protrude toward the output side L1. The positioning convex portions 116 are arranged at two locations spaced apart in the circumferential direction.

[0032] As shown in FIG. 3, the flange 45 of the bearing holder 42 facing the encoder case 11 has a flat surface 452 with no irregularities over the entire range of the region on the outer peripheral side of the annular wall 46. The sealing material 48 is interposed between the sealing material placement surface 115 of the encoder case 11 and the flat surface 452 of the motor case 4. Further, on the outer peripheral side of the sealing material 48, the abutting portion 114 of the encoder case 11 abuts against the flat surface 452. Thereby, the encoder case 11 is positioned in the direction of the central axis L with respect to the motor case 4. At this time, when the positioning convex portion 116 provided on the encoder case 11 is fitted into the positioning concave portion 453 provided on the flat surface 452 of the motor case 4, the fixing holes 117 that open to each abutting portion 114 overlap with the screw holes 454 provided on the flat surface 452 of the motor case 4. Therefore, screwing with a fixing screw (not shown) becomes possible.

[0033] (Cover) As shown in FIGS. 2 and 3, the cover 12 includes a cover end plate portion 121 that faces the substrate 13 from the side opposite to the magnet 14 (the anti-output side L2), and a cover side plate portion 122 that extends from the outer peripheral edge of the cover end plate portion 121 to the output side L1. The cover end plate portion 121 covers the substrate 13 from the side opposite to the magnet 14 (the anti-output side L2). The cover side plate portion 122 surrounds the outer peripheral side of the substrate 13. The cover side plate portion 122 extends to the output side L1 beyond the magnetosensitive element 17 disposed on the surface of the substrate 13 on the output side L1. The cover 12 is positioned in the direction of the central axis L by being fixed to the encoder case 11.

[0034] The cover 12 has an opening 123 facing the side opposite to the wiring extraction portion 113 (the X2 side). The opening 123 is a notch formed by linearly cutting a part of the circumferential direction of the cover end plate portion 121 and the cover side plate portion 122 in a plane orthogonal to the radial direction. As shown in FIG. 2, the end portion of the substrate 13 on the X2 side is disposed outside the opening 123. A connector 18 that linearly extends in the Y direction along the opening 123 is disposed between the edge on the X2 side of the substrate 13 and the opening 123. The connector 18 is disposed outside the opening 123.

[0035] The encoder cable 5 is connected to the connector 18 from the side opposite to the wiring extraction portion 113. As shown in FIG. 2, the encoder cable 5 is drawn out from the cable-side connector 6 that fits into the connector 18 to the X2 side, bent into a shape that folds back to the X1 side, and routed to the wiring extraction portion 113 through the gap between the cover end plate portion 121 and the encoder case 11.

[0036] The encoder cable 5 includes signal lines connected to the encoder circuit and a frame ground line insulated from the signal lines. At the cable-side connector 6 (see Figure 2) provided at the end of the encoder cable 5, terminals connected to the signal lines are provided. Further, the encoder cable 5 includes a branch line (not shown) branched from the cable-side connector 6. The round terminal attached to the end of the branch line is connected to the frame ground line of the encoder cable 5. The round terminal is screwed with a conductive screw into one of a plurality of fixing holes 451 provided in the flange 45 of the bearing holder 42. Thereby, the frame ground line is electrically connected to the motor case 4.

[0037] The cover 12 is fixed to the substrate 13 by a conductive fixing member 16. As shown in FIGS. 3 and 4, the cover 12 is provided with fixing holes 124 penetrating the cover end plate portion 121 at two positions spaced apart in the circumferential direction. Further, the substrate 13 is provided with fixing holes 131 at two positions facing the fixing holes 124 of the cover 12. By fitting one end of the two fixing members 16 into the fixing hole 131 and the other end into the fixing hole 124 of the cover 12, the cover 12 is fixed to the substrate 13.

[0038] As shown in FIG. 3, one of the two fixing holes 124 is a circular reference hole, and the other is an elongated hole 125 that is long in the circumferential direction. The fixing member 16 is a spring pin, and the end of the fixing member 16 is press-fitted into the fixing holes 124 and 131. By using a spring pin as the fixing member 16, rattling of the cover 12 in the circumferential direction is prevented. Therefore, the fixing member 16 can position the cover 12 in the circumferential direction. Note that the fixing member 16 may be fixed to the fixing hole 131 by soldering.

[0039] The fixing member 16 is made of a conductive metal (e.g., SUS). One of the two fixing holes 131 provided in the substrate 13 is a ground through hole 132 provided with a land that is electrically connected to the signal ground of the encoder circuit on the substrate 13. Therefore, the cover 12 is electrically connected to the signal ground of the encoder circuit provided on the substrate 13 via one of the two fixing members 16.

[0040] The cover 12 is made of a magnetic material having conductivity. For example, the cover 12 is made of a magnetic metal such as iron or permalloy. Therefore, the cover 12 absorbs magnetic noise such as external magnetic fields and electromagnetic wave noise, and shields the magnetosensitive element 17 and the encoder circuit from magnetic noise and electromagnetic wave noise. Also, as described above, the cover 12 is electrically connected to the signal ground of the encoder circuit. Therefore, since the substrate 13 is covered by the member at the signal ground potential, the magnetosensitive element 17 and the encoder circuit can be shielded from electrical noise such as frame ground noise from the motor case 4.

[0041] (Dust-proof member) As shown in FIG. 2, a dust-proof member 19 is disposed between the cover 12 and the substrate 13. The dust-proof member 19 is disposed in a linear arrangement region 20 (see FIG. 3) along the edge of the opening 123 of the cover 12. The dust-proof member 19 is an insulating porous body, and is, for example, a foam made of an insulating material such as rubber or urethane. In a state where the cover 12 is fixed to the substrate 13, the dust-proof member 19 is compressed between the cover end plate portion 121 and the substrate 13 to block the opening 123. Therefore, it is possible to suppress the intrusion of conductive foreign matter onto the substrate 13.

[0042] (Substrate) The substrate 13 is substantially circular when viewed in the direction of the central axis L, and the edge on the X2 side is linearly notched. On the substrate surface facing the reverse output side L2, circuit elements (not shown) constituting the encoder circuit and the connector 18 are arranged. Further, on the substrate surface facing the output side L1, the magnetosensing element 17 and two Hall elements (not shown) are arranged. The two Hall elements are arranged at angular positions separated by 90 degrees with reference to the position of the magnetosensing element 17.

[0043] The substrate 13 is fixed to the encoder case 11 together with the cover 12. When the encoder case 11 fixing the substrate 13 and the cover 12 is fixed to the motor case 4, as shown in FIG. 2, the magnetosensing element 17 and the magnet 14 face each other. The encoder 10 is assembled such that a predetermined gap is formed between the surface of the output side L1 of the magnetosensing element 17 and the magnet 14. The encoder 10 discriminates the period of the output of the magnetosensing element 17 obtained by one rotation of the magnet 14 by the two Hall elements.

[0044] (Fixing structure of the cover and the substrate) As shown in FIG. 8, on the inner surface of the encoder case 11, a seating surface 50 against which the cover 12 abuts from the output side L1 is provided. As shown in FIGS. 4 and 5, the seating surface 50 extends in an arc shape along the corner where the case end plate portion 111 and the case side plate portion 112 are connected. The seating surface 50 is the front end surface of the stepped portion protruding from the case end plate portion 111 to the output side L1, and is provided at two positions on the radially opposite side with respect to the central axis L. Each of the two seating surfaces 50 is provided with a recess 51 recessed toward the reverse output side L2. The recess 51 extends to the inner peripheral edge of the seating surface 50, and the seating surface 50 surrounds both circumferential sides and the outer peripheral side of the recess 51.

[0045] The encoder case 11 includes a board fixing portion 52 disposed inside the recess 51. The board fixing portion 52 is a convex portion that protrudes from the bottom surface of the recess 51 toward the output side L1. The recess 51 surrounds both sides in the circumferential direction and the outer peripheral side of the board fixing portion 52. The tip surface of the board fixing portion 52 is located on the output side L1 with respect to the seat surface 50. The board fixing portion 52 is provided at one location in each recess 51. Therefore, the encoder case 11 includes two board fixing portions 52 disposed on opposite sides in the radial direction with respect to the central axis L. Each board fixing portion 52 is provided with a fixing hole 53 for screwing the board 13. Further, a positioning convex portion 54 protruding from the tip surface of the board fixing portion 52 is provided on one of the two board fixing portions 52. Further, on the bottom surface of the recess 51, a relief portion 55 recessed toward the counter-output side L2 is provided at a position adjacent to the board fixing portion 52 in the circumferential direction.

[0046] As shown in FIGS. 3 and 4, the cover 12 includes an opening 61 that penetrates the cover end plate portion 121. The opening 61 has a shape into which the board fixing portion 52 fits and is provided at two locations on opposite sides in the radial direction with reference to the central axis L. Fixing holes 124 for attaching the above-described fixing member 16 are provided at positions adjacent to each other in the circumferential direction in each opening 61.

[0047] The board 13 includes fixing holes 62 for fixing to the encoder case 11. The fixing holes 62 are provided at two locations on opposite sides sandwiching the magneto-sensitive element 17. A positioning hole 64 is provided at a position adjacent to one of the fixing holes 62 in the circumferential direction. A positioning hole 64 is provided at a position adjacent to one of the fixing holes 62 in the circumferential direction.

[0048] (Assembly of the Encoder) When assembling the encoder case 11, the cover 12, and the substrate 13, follow the steps below. First, apply an adhesive to the seating surface 50 of the encoder case 11, and extend and arrange the encoder cable 5 in the X direction in the space between the two seating surfaces 50. Then, abut the cover 12 against the seating surface 50 from the output side L1 and fix it with an adhesive material. At this time, insert the substrate fixing portions 52 into the two openings 61 respectively, and project the substrate fixing portions 52 inside the cover 12. At this time, at positions adjacent in the circumferential direction with respect to the substrate fixing portion 52, the fixing hole 124 provided in the cover 12 and the relief portion 55 provided on the bottom surface of the recess 51 face each other.

[0049] Next, fit the cable-side connector 6 of the encoder cable 5 drawn out from the gap in the X2 direction between the encoder case 11 and the cover 12 to the connector 18 of the substrate 13 to which the two fixing members 16 are attached. Then, by abutting the substrate 13 against the substrate fixing portion 52 protruding inside the cover 12 from the output side L1, position the substrate 13 in the direction of the central axis L. Also, at this time, fit the positioning convex portion 54 into the positioning hole 64 of the substrate 13, and fit the ends of the two fixing members 16 into the fixing holes 124 of the cover 12 to position the substrate 13 in the circumferential direction. As a result, the fixing hole 62 of the substrate 13 and the fixing hole 53 of the encoder case 11 overlap. Therefore, pass the fixing screw 63 for fixing the substrate through the fixing hole 62, and screw the tip of the fixing screw 63 into the fixing hole 53 to fix the substrate 13 to the encoder case 11. At this time, since the tip of the fixing member 16 fitted into the fixing hole 24 of the cover 12 from the substrate 13 side faces the relief portion 55 provided in the encoder case 11, even if the tip of the fixing member 16 protrudes from the fixing hole 24, interference with the encoder case 11 can be avoided.

[0050] Subsequently, the encoder case 11 to which the substrate 13 and the cover 12 are fixed is screwed to the bearing holder 42 of the motor 3 to which the magnet holder 15 and the magnet 14 are fixed on the rotating shaft 2. As a result, the magnet 14 and the magnetosensitive element 17 face each other with a predetermined gap. For the motor 1 with an encoder after assembly, the output of the encoder 10 is corrected so that the rotation position of the rotating shaft 2 coincides with the position information output from the encoder 10.

[0051] (Main operational effects of this embodiment) As described above, the motor 1 with an encoder according to this embodiment includes an encoder 10 and a motor 3 having a rotating shaft 2. The encoder 10 includes a magnet 14 that rotates integrally with the rotating shaft 2, and a substrate 13 on which a magnetosensitive element 17 facing the magnet 14 is disposed. Further, the encoder 10 has a cover 12 that covers the substrate 13 from the side opposite to the magnet 14 (the anti-output side L2), and an encoder case 11 that houses the magnet 14 and the substrate 13 and has the cover 12 fixed to its inner surface. The encoder case 11 includes a substrate fixing portion 52 disposed inside the cover 12, and the substrate 13 is fixed to the substrate fixing portion 52.

[0052] In this embodiment, the substrate 13 of the encoder 10 is fixed to the substrate fixing portion 52 provided in the encoder case 11. Therefore, since an encoder holder fixed to the parts on the motor 3 side is not required, the number of parts can be reduced. In addition, in order to ensure the encoder accuracy, instead of increasing the positional accuracy between the substrate 13 and the magnet 14, the output of the encoder may be measured after the encoder 10 is assembled, and the output may be corrected so as to obtain the required encoder accuracy. Therefore, since an encoder holder is not required and the dimensional accuracy of other parts does not need to be increased, the component cost can be suppressed without degrading the performance of the encoder. Further, since there is no encoder holder serving as a heat transfer path between the substrate 13 and the motor 3, and the encoder case 11 to which the substrate 13 is fixed is in contact with the outside air, it is easy to dissipate the heat transmitted from the motor 3. Therefore the influence of the heat generation of the motor 3 on the encoder 10 can be suppressed.

[0053] In this embodiment, the encoder case 11 includes a case end plate portion 111 provided with a seating surface 50 against which the cover 12 abuts, and a case side plate portion 112 extending from the outer peripheral edge of the case end plate portion 111 toward the side of the magnet 14 (output side L1). The seating surface 50 is provided with a recess 51 that recesses toward the side opposite to the cover 12. The board fixing portion 52 is provided inside the recess 51, and the tip of the board fixing portion 52 is located on the magnet 14 side (output side L1) with respect to the seating surface 50. The cover 12 includes an opening 61 in which the board fixing portion 52 is disposed, and the opening 61 is located inside the recess 51. Therefore, when assembling the encoder 10, the cover 12 is abutted against and fixed to the seating surface 50 of the encoder case 11, and then the board 13 may be fixed to the board fixing portion 52 protruding inside the cover 12 from the opening 61 of the cover 12. Thus, the cover 12 and the board 13 can be assembled to the encoder case 11 from the same direction. Therefore, the assembly work is easy. Further, it is possible to avoid a situation where burrs formed at the edge of the opening 61 during the manufacture of the cover 12 hit the seating surface 50 and the positional accuracy of the cover 12 decreases.

[0054] In this embodiment, the cover 12 is made of a conductive magnetic member, and includes a cover end plate portion 121 that abuts against the seating surface 50, and a cover side plate portion 122 that extends from the outer peripheral edge of the cover end plate portion 121 toward the side of the magnet 14 (output side L1) and surrounds the outer peripheral side of the board 13. Therefore, the outer peripheral side of the board 13 and the side opposite to the magnet 14 can be surrounded by the conductive magnetic member, so that the magnetosensitive element 17 and the encoder circuit on the board 13 can be shielded from magnetic noise such as external magnetic fields and electrical noise. Further, the cover end plate portion 121 is provided with a fixing hole 124 into which a conductive fixing member 16 protruding from the board 13 is fitted, and the conductive fixing member 16 electrically connects the signal ground of the encoder circuit on the board 13 and the cover 12. Therefore, since the cover 12 functions as a shield for the signal ground potential, it is possible to reduce the influence of frame ground noise and power supply noise from the motor 3 side on the magnetosensitive element 17 and the encoder circuit of the board 13.

[0055] In this embodiment, on the encoder case 11, substrate fixing portions 52 are provided at two locations on the diametrically opposite sides with respect to the central axis L of the rotation shaft 2. Therefore, since the outer peripheral portion of the substrate 13 can be supported at two locations, the inclination of the substrate 13 can be suppressed. Note that the substrate fixing portions 52 may be provided at a plurality of positions spaced apart in the circumferential direction, and may be three or more.

[0056] In this embodiment, a positioning convex portion is provided at one of the two substrate fixing portions 52, and the substrate 13 is provided with a positioning hole into which the positioning convex portion fits. Therefore, since the substrate 13 can be directly positioned with respect to the encoder case 11, the positioning accuracy of the substrate 13 can be improved.

[0057] In the motor 1 with encoder of this embodiment, the motor 3 includes a motor case 4 to which the encoder case 11 is fixed, and a sealing material 48 interposed between the encoder case 11 and the motor case 4. In this way, by assembling with the sealing material 48 interposed between the encoder case 11 and the motor case 4, the heat of the motor 3 is less likely to be transmitted to the encoder case 11. Therefore, since the heat of the motor is less likely to be transmitted to the substrate 13 supported by the encoder case 11, the influence of the heat generation of the motor 3 on the encoder 10 can be reduced.

[0058] The motor 1 with encoder of this embodiment has an encoder cable 5 connected to a connector 18 disposed on the substrate 13 of the encoder 10. The encoder cable 5 includes a signal line connected to a wiring pattern provided on the substrate 13 and a frame ground line insulated from the signal line, and the frame ground line is fixed to the motor case 4 via a conductive screw. Therefore, since the encoder cable 5 can be connected to the motor case 4 at the frame ground potential the electrical noise generated from the encoder cable 5 can be reduced.

[0059] (Modification example) (1) In the above-described embodiment, the encoder case 11 is provided with an abutting portion 114 that abuts against the motor case 4 on the end face thereof, and a seal member placement surface 115 on which the seal member 48 is disposed. The encoder case 11 and the motor case 4 are configured to directly abut against each other at the abutting portion 114. However, a configuration in which the encoder case 11 and the motor case 4 do not directly abut against each other may be adopted. That is, the encoder case 11 may adopt a configuration in which a portion excluding the seal member placement surface 115 is separated from the motor case 4.

[0060] (2) In the above-described embodiment, the encoder case 11 is provided with an abutting portion 114 that protrudes toward the motor case 4 side from the seal member placement surface 115 on the end face thereof. However, the entire end face of the output side L1 of the encoder case 11 may be a flat surface, and a seal member placement surface on which the seal member 48 is disposed on the end face (flat surface 452) of the motor case 4, and an abutting portion that protrudes toward the encoder case 11 side from the seal member placement surface may be provided.

[0061] (Other Embodiment) (1) In the above-described embodiment, the cover 12 has a shape that covers the anti-output side L2 and the outer peripheral side of the substrate 13, and the output side L1 of the substrate 13 is not covered. However, a structure including a shield member that covers the substrate 13 from the output side L1 may be adopted. For example, a disk-shaped cover plate made of the same material as the cover 12 is attached so as to close the end portion of the output side L1 of the cover 12, a plate opening that faces the magneto-sensitive element 17 is provided at the center of the cover plate, and the plate opening is covered with a film-shaped shield member made of a conductive metal (for example, aluminum). By doing so, the magneto-sensitive element 17 and the encoder circuit can be shielded from magnetic noise and electrical noise that enter from the magnet 14 side. In addition, since the cover plate and the shield member are connected to the signal ground of the encoder circuit via the cover 12, the influence of frame ground noise and power supply noise that enter from the magnet 14 side can be reduced.

[0062] (2) In the above-described embodiment, a cover 12 made of a conductive magnetic material is disposed inside the encoder case 11 to shield the substrate 13 from magnetic noise and electromagnetic wave noise. However, if the encoder case 11 is made of a conductive magnetic material (for example, iron, permalloy, etc.), the cover 12 can be omitted. As a result, the number of components can be reduced, and cost reduction can be achieved. It is also advantageous for miniaturization of the encoder. That is, the present invention has a motor 3 provided with a rotating shaft 2 and an encoder for detecting the rotation of the rotating shaft 2. The encoder includes a magnet 14 that rotates integrally with the rotating shaft 2, a substrate 13 on which a magnetic sensing element 17 facing the magnet 14 is disposed, and an encoder case 11 that houses the magnet 14 and the substrate 13. The substrate 13 is fixed to a substrate fixing portion 52 provided on the inner surface of the encoder case 11 made of a conductive magnetic material. The motor 3 can be applied to a configuration including a motor case 4 to which the encoder case 11 is fixed and a sealing material 48 interposed between the encoder case 11 and the motor case 4.

[0063] (3) In each of the above-described embodiments, a heat dissipation structure such as fins may be provided on the encoder case 11. Thereby, the heat transmitted from the encoder case 11 to the substrate 13 can be further reduced. Therefore, the influence of the heat generation of the motor 3 can be further reduced.

Explanation of Reference Numerals

[0064] 1... motor with encoder, 2... rotating shaft, 3... motor, 4... motor case, 5... encoder cable, 6... cable-side connector, 10... encoder, 11... encoder case, 12... cover, 13... substrate, 14... magnet, 15... magnet holder, 16... fixing member, 17... magnetic sensing element, 18... connector, 19... dust-proof member, 20... arrangement region, 41... cylindrical case, 42... shaft Holder, 43... Bearing, 44... Circular recess, 45... Flange, 46... Annular wall, 47... Plate, 48... Sealing material, 50... Seating surface, 51... Recess, 52... Substrate fixing part, 53... Fixing hole, 54... Positioning projection, 55... Relief part, 61... Opening, 62... Fixing hole, 64... Positioning hole, 111... Case end plate part, 112... Case side plate part, 113... Wiring extraction part, 114... Contact part, 115... Sealing material placement surface, 116... Positioning projection, 117... Fixing hole, 121... Cover end plate part, 122... Cover side plate part, 123... Opening, 124... Fixing hole, 125... Long hole, 131... Fixing hole, 132... Ground through hole, 151... Magnet holding part, 152... Shaft part, 153... Shield part, 154... Set screw, 451... Fixing hole, 452... Flat surface, 453... Positioning recess, 454... Threaded hole, 461... Notch part, 471... Protrusion, L... Central axis, L1... Output side, L2... Reverse output side

Claims

1. A magnet that rotates integrally with a rotating shaft, a substrate on which a magnetosensitive element facing the magnet is disposed, a cover that covers the substrate from the side opposite to the magnet, an encoder case that houses the magnet and the substrate, and has the cover fixed to an inner surface thereof, the encoder case includes a substrate fixing portion disposed inside the cover, the substrate is fixed to the substrate fixing portion, the encoder case is provided with the substrate fixing portions at a plurality of positions spaced in the circumferential direction with respect to the central axis of the rotating shaft, each of the plurality of substrate fixing portions abuts on an outer peripheral portion of the substrate. An encoder characterized by this.

2. The encoder case includes a case end plate portion provided with a seating surface on which the cover abuts, and a case side plate portion extending from an outer peripheral edge of the case end plate portion toward the magnet side, a recess that recesses toward the side opposite to the cover is provided on the seating surface, the substrate fixing portion is provided inside the recess, and a tip of the substrate fixing portion is located on the magnet side with respect to the seating surface, the cover includes an opening in which the substrate fixing portion is disposed, and the opening is located inside the recess. The encoder according to claim 1, characterized by this.

3. the cover is made of a magnetic member having conductivity, the cover includes a cover end plate portion that abuts on the seating surface, and a cover side plate portion that extends from an outer peripheral edge of the cover end plate portion toward the magnet side and surrounds an outer peripheral side of the substrate, the cover end plate portion includes a fixing hole into which a conductive fixing member protruding from the substrate is fitted. The encoder according to claim 2, characterized by this.

4. At least one of the plurality of substrate fixing portions is provided with a positioning convex portion, the substrate includes a positioning hole into which the positioning convex portion is fitted. The encoder according to claim 1, characterized by this.

5. An encoder according to any one of claims 1 to 4, and a motor including the rotating shaft. A motor with an encoder, characterized by this.

6. The motor includes a motor case to which the encoder case is fixed, and a sealing material interposed between the encoder case and the motor case. The motor with an encoder according to claim 5, characterized by this.

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