JP2019132808A - Rotation angle detection device - Google Patents

Abstract

To provide a rotation angle detection device capable of suppressing an increase in size of a circuit board for mounting a magnetic sensor and electronic components.SOLUTION: A rotation angle detection device comprises a rotation shaft 2, a housing 31 rotatably supporting the rotation shaft 2, a magnetic encoder 5 fixed on the rotation shaft 2, and a circuit board 7 provided oppositely to one end face 2c of the rotation shaft 2 and supported by the housing 31. The magnetic encoder 5 includes a magnetic track 5b in which an N-pole and an S-pole are alternately magnetized in a ring shape along a plane orthogonal to the rotation shaft 2. A surface 5c, on a circuit board 7 side, of the magnetic track 5b projects further to the circuit board 7 side than the one end face 2c. A magnetic sensor 6 detecting a magnetic field of the magnetic track 5b and electronic components 20 that are opposite to the one end face 2c and process a detection signal of the magnetic sensor 6 are mounted on the circuit board 7.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rotation angle detection device capable of detecting a rotation angle in various devices.

  Japanese Patent Laying-Open No. 2009-080058 (Patent Document 1) includes two magnetic encoders provided in concentric rings and having different numbers of magnetic poles, and two magnetic sensors that respectively detect the magnetic fields of the magnetic encoders. A rotation detection device is disclosed. Each magnetic sensor detects position information in the magnetic pole of the magnetic encoder. The phase difference of the magnetic field signal detected by each magnetic sensor is obtained, and the absolute angle of the magnetic encoder is calculated based on the phase difference.

JP 2009-080058 A

  In the rotation detection device disclosed in Japanese Patent Laying-Open No. 2009-080058, the gap between the magnetic encoder and the magnetic sensor is set small in order to detect the absolute angle with high accuracy. Therefore, the distance between the area near the magnetic sensor on the circuit board on which the magnetic sensor is mounted and the magnetic encoder is small, and a tall electronic component cannot be mounted in the area. Therefore, it is necessary to increase the size of the circuit board in order to secure a mounting area for tall electronic components.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotation angle detection device capable of suppressing an increase in size of a circuit board for mounting a magnetic sensor and an electronic component. is there.

  A rotation angle detection device according to an aspect of the present disclosure is provided to face a rotating shaft, a housing that rotatably supports the rotating shaft, a magnetic encoder fixed to the rotating shaft, and one end surface of the rotating shaft, And a circuit board supported by the housing. The magnetic encoder includes at least one magnetic track in which N and S poles are alternately magnetized in a ring shape along a plane perpendicular to the rotation axis. The surface on the circuit board side of the at least one magnetic track protrudes to the circuit board side from one end face of the rotating shaft. Mounted on the circuit board are a magnetic sensor that faces at least one magnetic track and detects a magnetic field of at least one magnetic track, and an electronic component that faces one end surface of the rotating shaft and processes a detection signal of the magnetic sensor Is done.

  Preferably, a concave portion is formed on one end surface of the rotation shaft. The electronic component is mounted on the circuit board so as to face the recess.

  Preferably, the at least one magnetic track includes a first magnetic track and a second magnetic track. The difference between the number of magnetic pole pairs of the first magnetic track and the number of magnetic pole pairs of the second magnetic track is one pole pair.

  Preferably, the electronic component performs a process of converting the detection signal into a signal having a specification different from the specification of the detection signal and outputting the signal.

  According to the rotation angle detection device of the present disclosure, an increase in size of a circuit board for mounting a magnetic sensor and an electronic component can be suppressed.

It is sectional drawing which shows an example of the rotation angle detection apparatus which concerns on embodiment. It is an expanded sectional view of the magnetic encoder vicinity with which the rotation angle detection apparatus shown in FIG. 1 is provided. It is sectional drawing which shows a magnetic encoder. It is a top view which shows a magnetic encoder. It is a figure which shows an example of the functional block comprised by the electronic component mounted in a circuit board.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a cross-sectional view illustrating an example of a rotation angle detection device according to an embodiment. FIG. 2 is an enlarged cross-sectional view of the vicinity of the magnetic encoder provided in the rotation angle detection device shown in FIG. As shown in FIG. 1, the rotation angle detection device 1 includes a rotation shaft 2, a bearing 9, a housing 31, a magnetic encoder 5, and a circuit board 7.

  The rotating shaft 2 is a stepped shaft. The large-diameter portion 2 a of the rotating shaft is rotatably supported by a pair of bearings 9. An annular protrusion 2b is provided in the middle of the outer peripheral surface of the large diameter portion 2a. The protrusion 2b is sandwiched between the inner rings of the pair of bearings 9 in a state where a preload is applied to the pair of bearings 9. A thin outer ring spacer 10 is sandwiched between the outer rings of the pair of bearings 9. Each of the pair of bearings 9 is constituted by, for example, a deep groove ball bearing with a seal.

  The housing 31 accommodates a part of the rotating shaft 2 and fixes the outer rings of the pair of bearings 9. The housing 31 includes a housing body 3 and a housing lid 4.

  The housing body 3 is cylindrical. The diameter of one opening 3a of the housing body 3 is smaller than the diameter of the other opening 3b. The inner surface of the housing body 3 includes an annular flat surface 3 c orthogonal to the rotation shaft 2 and an inner peripheral surface 3 d coaxial with the rotation shaft 2. The plane 3c is adjacent to the opening 3a. The inner peripheral surface 3d is adjacent to the flat surface 3c, and is located closer to the opening 3b than the flat surface 3c. The inner diameter of the inner peripheral surface 3d is smaller than the diameter of the opening 3b and slightly larger than the outer diameter of the outer ring of the bearing 9. A pair of bearing 9 is inserted from the opening part 3b, and is accommodated inside 3d of internal peripheral surfaces.

  The housing lid 4 is attached to the housing body 3 with bolts 14 so as to close the opening 3b of the housing body 3 in a state where the bearing 9 is accommodated inside the inner peripheral surface 3d of the housing body 3. At this time, the housing lid 4 covers the one end surface 2 c in the axial direction of the rotating shaft 2. An O-ring 13 is disposed between the housing lid 4 and the housing body 3. Further, a spacer 11 having an L-shaped cross section is disposed between the housing lid 4 and the outer ring of the bearing 9 on the housing lid 4 side of the pair of bearings 9. When the housing lid 4 is attached to the housing by the bolts 14, the pair of bearings 9 are pressed against the flat surface 3 c of the housing body 3 by the housing lid 4 and the spacer 11. As a result, the pair of bearings 9 are fixed in the housing body 3. As a result, the housing 31 rotatably supports the rotary shaft 2 via the pair of bearings 9. The spacer 11 may be omitted and the housing lid 4 may be in direct contact with the outer ring of the bearing 9.

  When the pair of bearings 9 are fixed in the housing 31, the small diameter portion 2 d of the rotating shaft 2 supported by the pair of bearings 9 protrudes from the opening 3 a of the housing body 3. An oil seal 16a is provided in the opening 3a, and a slinger 16b is disposed outside the opening 3a.

  The circuit board 7 is, for example, a glass epoxy flat disk-shaped printed board, is provided to face the one end surface 2 c of the rotating shaft 2, and is supported by the housing lid 4. The surface of the circuit board 7 includes a main plane 7a and a flat back surface 7b on the back side of the main plane 7a. The main plane 7a and the back surface 7b are parallel. A concave portion 4a having a circular shape in plan view is formed on the surface of the housing lid 4 on the rotating shaft 2 side, and the circuit board 7 is disposed in the concave portion 4a. At this time, the main plane 7a of the circuit board 7 faces the one end face 2c of the rotating shaft 2, and the back surface 7b of the circuit board 7 is in contact with the bottom surface of the recess 4a. The concave portion 4 a having a circular shape in plan view is processed so as to be coaxial with the rotation shaft 2. The diameter of the circuit board 7 is slightly smaller than the diameter of the recess 4a. Therefore, the circuit board 7 is accommodated in the recess 4a through a minute gap. The circuit board 7 is supported on the housing lid 4 by screws 8.

  The magnetic encoder 5 is fixed to the rotating shaft 2. Specifically, the magnetic encoder 5 is fixed to the outer peripheral surface of one end portion 2 f (see FIG. 1) of the rotating shaft 2 on the circuit board 7 side via the ring member 12. Note that the ring member 12 may be omitted, and the magnetic encoder 5 may be directly fixed to the outer peripheral surface of the one end 2f of the rotating shaft 2 by press-fitting or the like. Since the rotating shaft 2 is supported by the pair of bearings 9, the magnetic encoder 5 rotates stably without being affected by the disturbance acting on the rotating shaft 2.

  FIG. 3 is a cross-sectional view showing the magnetic encoder. FIG. 4 is a plan view showing the magnetic encoder. As shown in FIGS. 3 and 4, the magnetic encoder 5 includes a cored bar 5a and two rows of magnetic tracks 5b1 and 5b2. Hereinafter, when the magnetic tracks 5b1 and 5b2 are not particularly distinguished, each of the magnetic tracks 5b1 and 5b2 is referred to as a “magnetic track 5b”.

  The metal core 5a is obtained by press-molding an annular thin plate into an L-shaped cross section. The inner peripheral surface of the cored bar 5 a is fixed to the rotary shaft 2 via the ring member 12. The flange portion of the core metal 5 a protrudes outward in the radial direction of the rotating shaft 2.

  The magnetic track 5b has N poles and S poles alternately magnetized in a ring shape along a plane perpendicular to the rotation axis 2 of the metal core 5a. The ring-shaped magnetic track 5 b is coaxial with the rotating shaft 2 and protrudes outward in the radial direction of the rotating shaft 2. The magnetic track 5b is a rubber magnetic body obtained by vulcanizing and bonding an unvulcanized rubber material kneaded with a magnetic material, and is formed on the surface of the flange portion of the cored bar 5a on the circuit board 7 side. The magnetic track 5b2 is located inside the magnetic track 5b1. The difference between the number of magnetic pole pairs of the magnetic track 5b1 and the number of magnetic pole pairs of the magnetic track 5b2 is one pole pair. For example, the magnetic track 5b1 has 64 pole pairs, and the magnetic track 5b2 has 63 pole pairs. The magnetic track 5b1 is a main track serving as a reference for calculating the angle, and the magnetic track 5b2 is a subtrack for detecting the phase position.

  As shown in FIG. 2, the surface 5 c on the circuit board 7 side of the magnetic track 5 b projects from the one end face 2 c of the rotating shaft 2 toward the circuit board 7.

  A magnetic sensor 6 and a plurality of electronic components 20 are mounted on the circuit board 7. The magnetic sensor 6 and the plurality of electronic components 20 are mounted only on the main plane 7a on the rotating shaft 2 side of the circuit board 7, and are not mounted on the back surface 7b. Thereby, the enlargement of the rotation angle detection apparatus 1 is suppressed.

  Furthermore, a cable 15 that is electrically connected to the magnetic sensor 6 and the plurality of electronic components 20 is connected to the circuit board 7. The tip of the cable 15 penetrates from the back surface 7b toward the main plane 7a in a region facing the one end surface 2c of the rotating shaft 2 in the circuit board 7. The tip of the cable 15 is connected to the magnetic sensor 6 and the plurality of electronic components 20 via the wiring circuit on the main plane 7a. The cable 15 is drawn out through a through hole 4b formed in the bottom surface of the recess 4a of the housing lid 4. The through hole 4b is filled with a resin material.

  A liquid repellent having oil and water repellency may be applied to the surface of the circuit board 7 and the electronic component 20 so that condensation or grease on the bearing 9 does not pose a problem on the surface of the circuit board 7. . Alternatively, the surface of the electronic component 20 mounted on the circuit board 7 may be molded with a synthetic resin or the like. As the synthetic resin, urethane resin, epoxy resin, or the like can be used.

  The magnetic sensor 6 is mounted on the circuit board 7 at a position facing the magnetic track 5b, and detects the magnetic fluxes of the magnetic track 5b1 and the magnetic track 5b2. As described above, since the concave portion 4a in which the circuit board 7 is accommodated and the rotary shaft 2 are coaxial, and the ring-shaped magnetic track 5b and the rotary shaft 2 are coaxial, the magnetic track 5b and the magnetic sensor 6 are connected to each other. Easy alignment. The surface of the magnetic sensor 6 is separated from the surface of the magnetic track 5b with a minute gap (for example, about 0.4 mm). Thereby, the detection accuracy of the magnetic flux of the magnetic track 5b by the magnetic sensor 6 is increased. Further, as described above, since the rotary shaft 2 is supported by the pair of bearings 9, the magnetic encoder 5 is stably affected by the disturbance acting on the rotary shaft 2 and is stably rotated. For this reason, a minute gap between the magnetic track 5b and the magnetic sensor 6 can be kept constant, and the magnetic flux detection accuracy of the magnetic track 5b is further increased.

  The magnetic sensor 6 detects the absolute angle of the magnetic encoder 5 (the absolute angle of the rotating shaft 2) by utilizing the fact that the difference between the number of magnetic pole pairs of the magnetic track 5b1 and the number of magnetic pole pairs of the magnetic track 5b2 is one pole pair. The detection signal indicating the detection result is output. When the magnetic track 5b1 is a 64 pole pair and the magnetic track 5b2 is a 63 pole pair, the angle can be detected with a resolution (0.0014 degrees) of about 18 bits per rotation of the rotating shaft 2. Thereby, even if an assembly error is taken into consideration, measurement with an angular accuracy of ± 0.1 degrees or less is possible.

  The electronic component 20 processes the detection signal of the magnetic sensor 6. The electronic component 20 is mounted at a position facing the one end surface 2 c of the rotating shaft 2 on the main plane 7 a of the circuit board 7. As shown in FIG. 2, since the surface 5c on the housing lid 4 side of the magnetic track 5b protrudes toward the housing lid 4 side from the one end surface 2c of the rotating shaft 2, the circuit board in the inner diameter side region 17 of the magnetic track 5b. 7 and the one end face 2c are longer than the distance between the circuit board 7 and the surface 5c of the magnetic track 5b. Therefore, the electronic component 20 that is taller than the magnetic sensor 6 can be mounted on the circuit board 7.

  Further, a concave portion 2 e is formed on the one end surface 2 c of the rotating shaft 2. Thereby, the distance between the circuit board 7 and the bottom surface of the recess 2e is longer than the distance between the circuit board 7 and the one end face 2c. Therefore, a taller electronic component 20 can be mounted at a position facing the recess 2e in the circuit board 7.

  FIG. 5 is a diagram illustrating an example of a functional block configured by the electronic component 20 mounted on the circuit board 7. In the example illustrated in FIG. 5, the circuit board 7 includes an arithmetic processing unit 18 that performs arithmetic processing on the detection signal output from the magnetic sensor 6, and an output unit 19 that outputs a signal having a specification different from the specification of the detection signal. Are mounted on the electronic components. The arithmetic processing unit 18 performs processing for converting the detection signal of the serial communication specification into a signal of another specification (for example, a CAN (Controller Area Network) signal, a PWM (Pulse Width Modulation) signal, an analog signal). The output unit 19 outputs a signal (for example, CAN signal, PWM signal, analog signal) converted by the arithmetic processing unit 18. If the detection signal output from the magnetic sensor 6 is output to the outside, the number of electronic components 20 mounted on the circuit board 7 is small, but the number of electronic components 20 constituting the arithmetic processing unit 18 and the output unit 19 is small. Will be more. Furthermore, the arithmetic processing unit 18 and the output unit 19 are configured by tall electronic components 20 such as a one-chip microcomputer, an electrolytic capacitor, and a protection circuit element. With the rotation angle detection device 1 shown in FIGS. 1 and 2, such a plurality of tall electronic components 20 can be mounted on the circuit board 7.

  In the above description, the difference between the number of magnetic pole pairs of the magnetic track 5b1 and the number of magnetic pole pairs of the magnetic track 5b2 is one pole pair, but two or more pole pairs may be used. When the relative position of the magnetic encoder 5 is detected, the magnetic encoder 5 may include only one row of magnetic tracks 5b, and a magnetic sensor 6 that can be multiplied is used.

  Further, the number of electronic components 20 mounted on the circuit board 7 is not particularly limited, and may be one or two or more.

  As described above, the rotation angle detection device 1 according to the embodiment includes the housing 31 that rotatably supports the rotating shaft 2, the magnetic encoder 5 that is fixed to the rotating shaft 2, and the one end surface 2 c of the rotating shaft 2. And a circuit board 7 supported by the housing 31 so as to cover. The magnetic encoder 5 includes at least one magnetic track 5b in which N and S poles are alternately magnetized in a ring shape along a plane orthogonal to the rotation axis 2. A surface 5c on the housing lid 4 side of the magnetic track 5b protrudes toward the housing lid 4 from the one end face 2c. On the circuit board 7, a magnetic sensor 6 that faces the magnetic track 5b and detects the magnetic field of the magnetic track 5b, and an electronic component 20 that faces the one end face 2c and processes the detection signal of the magnetic sensor 6 are mounted. .

  According to said structure, the distance of the circuit board 7 and the one end surface 2c is longer than the distance of the circuit board 7 and the surface 5c of the magnetic track 5b. Therefore, an electronic component 20 that is taller than the magnetic sensor 6 can be mounted at a position facing the one end surface 2 c of the circuit board 7. The position facing the one end surface 2 c in the circuit board 7 is the inner diameter side of the position facing the magnetic track 5 b in the circuit board 7. As a result, an increase in size of the circuit board 7 for mounting the magnetic sensor 6 and the electronic component 20 can be suppressed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  DESCRIPTION OF SYMBOLS 1 Rotation angle detection apparatus, 2 Rotating shaft, 2a Large diameter part, 2b Projection part, 2c One end surface, 2d Small diameter part, 2e Recessed part, 2f One end part, 3 Housing body, 3a, 3b Opening part, 3c Plane, 3d Peripheral surface, 4 housing lid, 4a recess, 4b through hole, 5 magnetic encoder, 5a cored bar, 5b1, 5b2, 5b magnetic track, 5c surface, 6 magnetic sensor, 7 circuit board, 7a main plane, 7b back surface, 8 screw , 9 Bearing, 10 Outer ring spacer, 11 Spacer, 12 Ring member, 13 Ring, 14 Bolt, 15 Cable, 16a Oil seal, 16b Slinger, 17 Inner diameter side region, 18 Arithmetic processing unit, 19 Output unit, 20 Electronic component, 31 Housing.

Claims (4)

A rotation axis;
A housing that rotatably supports the rotating shaft;
A magnetic encoder fixed to the rotating shaft;
A circuit board provided opposite to one end surface of the rotating shaft and supported by the housing;
The magnetic encoder includes at least one magnetic track in which N and S poles are alternately magnetized in a ring shape along a plane orthogonal to the rotation axis,
The surface on the circuit board side of the at least one magnetic track protrudes to the circuit board side from one end face of the rotating shaft,
The circuit board is opposed to the at least one magnetic track, detects a magnetic field of the at least one magnetic track, and faces one end surface of the rotating shaft, and processes a detection signal of the magnetic sensor. A rotation angle detection device on which electronic components are mounted. A concave portion is formed on one end surface of the rotating shaft,
The rotation angle detection device according to claim 1, wherein the electronic component is mounted on the circuit board so as to face the recess. The at least one magnetic track includes a first magnetic track and a second magnetic track;
The rotation angle detection device according to claim 1 or 2, wherein a difference between the number of magnetic pole pairs of the first magnetic track and the number of magnetic pole pairs of the second magnetic track is one pole pair.   4. The rotation angle detection device according to claim 1, wherein the electronic component performs a process of converting the detection signal into a signal having a specification different from the specification of the detection signal and outputting the converted signal. 5.

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