JP5886269B2 - Rotation detection device and motor - Google Patents

Description

  The present invention relates to a rotation detection device.

  2. Description of the Related Art Conventionally, a rotation detection device has been devised that detects a magnetic position of a magnet fixed to a rotating body using a Hall element, which is a kind of magnetic sensor, and detects the rotational position of the rotating body. For example, an angle sensor is known that outputs an analog signal in a predetermined angle range by using a linear portion of an output corresponding to an angle change by bringing a Hall element close to a side surface of a cylindrical magnet (see Patent Document 1). ). In addition, in the rotation detection device, a configuration in which a magnetic flux guide member that guides the magnetic field lines emitted from the magnet to the Hall element has been devised (see Patent Document 2).

JP 2003-324930 A US 6016055 specification Japanese Patent No. 3152625

  By the way, the rotating body may require some play in the direction of the rotation axis depending on its configuration and usage. In such a case, it is necessary to arrange the rotation detection sensor at a position in consideration of play, and there is room for further improvement from the viewpoint of layout and space saving.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for realizing a rotation detection device in a space-saving manner.

  In order to solve the above-described problem, a rotation detection device according to an aspect of the present invention includes a rotation shaft, a sensor magnet fixed to the rotation shaft, and a periodic variation formed by the sensor magnet when the rotation shaft rotates. A sensor for detecting a magnetic field. The sensor has an element that uses the Hall effect, and is arranged so that the magnetosensitive surface of the element is not perpendicular to the magnetization vector of the sensor magnet.

  Here, the magnetization vector can be defined as the direction from the S pole to the N pole in the magnet. According to this aspect, the Hall element can be arranged at a position where the magnetic sensitive surface of the Hall element is parallel or oblique to the magnetization vector of the sensor magnet. Therefore, the freedom degree of arrangement | positioning of a Hall element increases and it can implement | achieve a rotation detection apparatus in space saving. Here, the magnetosensitive surface is the surface of the semiconductor thin film that generates the Hall effect inside the rotation detection device, and can be defined as a region where a magnetic flux that actually intersects the Hall element can be detected. In general, the surface is often parallel to the outer surface of the case in which the element is accommodated.

  The sensor may be arranged at a position deviating from the extension line of the magnetization vector passing through the magnetization center of the sensor magnet. Thereby, the magnetic flux which a sensor catches increases.

  The sensor may be disposed outside the outer periphery of the sensor magnet when viewed from the axial direction of the rotation shaft. Thereby, a sensor and a sensor magnet can be brought closer in the axial direction of the rotating shaft.

  The sensor may be arranged so that an angle formed by the magnetic sensitive surface of the sensor and the axial direction of the rotation axis is in a range of 90 ° ± 45 °. Thereby, the space efficiency at the time of arrange | positioning a sensor improves, and the diameter of the whole rotation detection apparatus can be reduced.

  You may further provide the magnetic member into which the magnetic force line which came out of the sensor magnet enters. The sensor may be provided in the middle of a path where the magnetic flux goes from the sensor magnet to the magnetic member. Thereby, the magnetic flux is efficiently guided to the sensor, and a stable output can be obtained. In addition, even if a sensor magnet having a high magnetic flux density is not used, an amount of magnetic flux necessary for detection can be guided to the sensor. Therefore, it becomes possible to use a low grade magnet, and material cost is reduced.

  Another embodiment of the present invention is a motor. This motor includes the above-described rotation detection device, a rotor fixed to the rotation shaft, and a cylindrical housing in which the rotor is housed and which has openings at at least one of both ends in the axial direction. The rotation detection device is attached in the vicinity of the opening.

  According to this aspect, it is possible to realize a motor that is provided with a rotation detection device and that is shorter in the axial direction or smaller in diameter.

  You may further provide the holder and end plate which were provided in the opening part. The holder may have a first surface on the housing side that intersects the direction of the rotation axis, and a second surface opposite to the first surface. The second surface may have a recess. The rotation detection device may be disposed in the recess. The end plate includes a magnetic material, abuts on the second surface of the holder, and may be disposed in a region close to the rotation detection device. Thereby, the magnetic field lines are efficiently guided to the sensor, and a stable output can be obtained.

  A stator magnet fixed to the inner peripheral surface of the housing may be further provided. The rotation detection device is configured such that the sensor is on the opposite side of the stator magnet with the sensor magnet interposed therebetween, and the sensor, the sensor magnet, and the stator magnet may be arranged in this order along the rotation axis direction. Thereby, since a sensor magnet is arrange | positioned between a sensor and a stator magnet, the influence which the magnetic force line produced from a stator magnet has on a sensor is suppressed.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, etc. are also effective as an aspect of the present invention.

  According to the present invention, the rotation detection device can be realized in a space-saving manner.

It is a front view of the motor concerning a 1st embodiment. It is sectional drawing of the motor which concerns on 1st Embodiment. FIG. 3A and FIG. 3B are schematic views of a schematic configuration of a rotation detection device according to a reference example. FIG. 4A is a schematic diagram of a schematic configuration of the rotation detection device according to the first embodiment, and FIG. 4B is a schematic configuration of the rotation detection device according to a modification of the first embodiment. It is a schematic diagram. Fig.5 (a)-FIG.5 (c) are schematic diagrams which show schematic structure of the rotation detection apparatus which concerns on 2nd Embodiment. It is a schematic diagram for demonstrating the area | region suitable for arrangement | positioning of a sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. Moreover, the structure described below is an illustration and does not limit the scope of the present invention at all.

(First embodiment)
FIG. 1 is a front view of the motor according to the first embodiment. FIG. 2 is a cross-sectional view of the motor according to the first embodiment.

  A DC brush motor (hereinafter referred to as “motor”) 10 according to the first embodiment mainly includes a housing 12 as a yoke housing, a rotor 14, a brush holder 16 with a connector, and a metal cover. An end plate 18 that is a member and a rotation detection device 100 described later are provided. The housing 12 has an opening 12a at one end in the axial direction X and a closed bottom 12b at the other end. The bottom 12b is formed with a recess, and the bearing 17 is accommodated in the recess. An arcuate stator magnet 19 is disposed on the inner wall of the housing 12. Moreover, the housing 12 and the end plate 18 are comprised with the electromagnetic steel plate which is a ferromagnetic body with low holding power.

  The rotor 14 includes a shaft 20, a core 22, a winding 24, and a commutator (commutator) 26, and is fixed to the shaft 20. The shaft 20 is a rotating shaft that is rotatably supported by the housing 12 and the end plate 18 via the bearing 17 and the bearing 28. The shaft 20 also functions as an output shaft. The bearing 28 is accommodated in a recess formed in the central portion of the end plate 18. The core 22 is formed by laminating a plurality of steel plates, and the shaft 20 is fixed in a state where the shaft 20 passes through the core 22. The winding 24 is wound around the groove 22a of the core 22, and generates a magnetic force when a current flows.

  The commutator 26 is fixed to the shaft 20 similarly to the core 22. The commutator 26 is a contact that allows a current supplied through a brush (not shown) to contact the coil 24 to flow through the winding 24 at an appropriate timing. The brush is, for example, a carbon brush mainly composed of graphite or the like. The brush may be a fork-shaped metal brush mainly composed of a noble metal or the like.

  The brush holder 16 is attached to the opening 12a of the cylindrical housing 12 in which the rotor 14 is accommodated, and a power supply path to the rotor 14 via the brush is provided. In the middle of the power supply path, a noise suppression element such as a choke coil 32, a capacitor, or a varistor is mounted, and a circuit board 34 on which wirings connecting the elements are formed on the surface is provided.

  The brush holder 16 is provided at a position that protrudes in a radial direction from the outer edge of the lid 16a and a circular lid 16a corresponding to the shape of the opening 12a of the housing 12, and current is supplied from an external power source. And a connector portion 16b to which a power feeding terminal is connected. Input terminals (terminals) 35a and 35b are provided inside the connector portion 16b.

  Next, the rotation detection device will be described in detail. FIG. 3A and FIG. 3B are schematic views of a schematic configuration of a rotation detection device according to a reference example.

  3A includes a rotation shaft 202, a sensor magnet 204 fixed to the rotation shaft 202, and a periodically varying magnetic field formed by the sensor magnet 204 when the rotation shaft 202 rotates. A sensor 206 that detects a signal correlated with (magnetic field), and a substrate 208 on which the sensor 206 is mounted. The sensor magnet 204 is configured such that the magnetization vector M is parallel to the rotation axis 202. The sensor magnet 204 is formed with a plurality of pairs of N and S poles alternately in the circumferential direction so that the magnetization vector M is periodically inverted. The sensor 206 has a Hall element.

  The sensor 206 in the rotation detection device 200 is arranged so that the magnetic sensitive surface 206 a is perpendicular to the magnetization vector M of the sensor magnet 204. Since the motor has end play (movement and play in the axial direction of the rotating shaft 202) depending on specifications and applications, it is necessary to set the distance d1 between the sensor 206 and the sensor magnet 204 to be somewhat large. In that case, it is necessary to secure an extra space in the axial direction of the rotation detection device 200, and there is room for improvement from the viewpoint of space saving of the rotation detection device.

  3B includes a rotation shaft 302, a sensor magnet 304 fixed to the rotation shaft 302, and periodic fluctuations formed by the sensor magnet 304 when the rotation shaft 302 rotates. A sensor 306 with a lead for detecting a signal having a correlation with a magnetic field (magnetic field) and a substrate 308 on which the sensor 306 with a lead is mounted. The sensor magnet 304 is configured such that the magnetization vector M is perpendicular to the rotation axis 302.

  The sensor 306 in the rotation detection device 300 is arranged so that the magnetic sensitive surface 306 a is perpendicular to the magnetization vector M of the sensor magnet 304. In this case, the sensor 306 in the rotation detection device 300 needs to be arranged outside the sensor magnet 304, and it is necessary to secure a large space in the radial direction of the rotation detection device 300. From the viewpoint of space saving of the rotation detection device. There is room for improvement.

  Based on such knowledge, the inventors have come up with a new configuration of a space-saving rotation detection device.

  4A is a schematic diagram of a schematic configuration of the rotation detection device 100 according to the first embodiment, and FIG. 4B is a schematic diagram of the rotation detection device 110 according to a modification of the first embodiment. It is a schematic diagram of a structure.

  The rotation detection device 100 shown in FIG. 4A includes a shaft 20, an annular sensor magnet 104 fixed to the shaft 20, and a periodically changing magnetic field formed by the sensor magnet 104 when the shaft 20 rotates. And a sensor 106 for detection. The sensor 106 has a Hall element which is a kind of magnetoelectric conversion element, and is mounted on the circuit board 34. The sensor 106 can be mounted on either side of the circuit board 34. The sensor magnet 104 is configured such that the magnetization vector M is perpendicular to the shaft 20, and a plurality of magnetic poles are arranged in the circumferential direction.

  The sensor 106 in the rotation detection device 100 is arranged so that the magnetic sensitive surface 106 a is not perpendicular to the magnetization vector M of the sensor magnet 104. Thereby, the Hall element can be arranged at a position where the magnetic sensitive surface 106 a of the Hall element is parallel or oblique to the magnetization vector M of the sensor magnet 104. Further, the sensor 106 is disposed at a position deviating from the extension line E of the magnetization vector M passing through the magnetization center of the sensor magnet 104. Thus, in the rotation detection device 100, the degree of freedom of arrangement of the sensor 106 having the Hall element is increased, and the rotation detection device 100 can be realized in a space-saving manner.

  Here, the magnetosensitive surface 106a is a surface of the semiconductor thin film that generates the Hall effect inside the rotation detecting device 100, and can be defined as a region where a magnetic flux that actually intersects the Hall element can be detected. In general, the surface is often parallel to the outer surface 106b of the case in which the Hall element is accommodated. The magnetic sensitive surface can also be regarded as sensing an orthogonal component of the magnetic flux intersecting with the surface. The center of magnetization can be considered as a point where the axial component of the magnet surface magnetic flux becomes minimum in the axial length range of the magnet, for example.

The sensor 106 is arranged at a position where the magnetosensitive surface 106a and the extension line E of the magnetization vector M passing through the magnetization center do not intersect. Further, the sensor 106 is disposed on the outer side in the radial direction with respect to the outer peripheral surface 104 a of the sensor magnet 104 when viewed from the axial direction of the shaft 20. Therefore, even if the shaft 20 moves in the axial direction, the sensor magnet 104 and the sensor 106 do not interfere with each other. Therefore, the sensor 106 and the sensor magnet 104 can be brought closer in the axial direction of the shaft 20. For example, in the case of the rotation detection device 110 shown in FIG. 4B, the circuit board 34 on which the sensor 106 is mounted is brought close to the front vicinity region of the outer peripheral surface 104 a of the sensor magnet 104. That is, when viewed from the radial direction of the shaft 20, the sensor magnet 104 and the sensor 106 can be arranged so as to overlap each other, and the rotation detecting device 100 can be thinned. Further, the diameter and size of the sensor magnet 104 can be reduced, and the material cost can be reduced.

(Second Embodiment)
Fig.5 (a)-FIG.5 (c) are schematic diagrams which show schematic structure of the rotation detection apparatus which concerns on 2nd Embodiment. In the following description, the same components as those of the rotation detection device 100 according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

  The rotation detection device 120 shown in FIG. 5A further includes an end plate 18 as a magnetic member into which the magnetic lines of force L emitted from the sensor magnet 104 enter. The sensor 106 is provided in the middle of a path along which the magnetic lines of force L are directed from the sensor magnet 104 to the end plate 18. Thereby, the magnetic force line L is efficiently guided to the sensor 106, and a stable sensor output is obtained. Further, even if a sensor magnet having a high magnetic flux density is not used, an amount of magnetic force lines necessary for detection can be guided to the sensor 106. Therefore, it becomes possible to use a low grade magnet, and material cost is reduced.

  In the rotation detection device 130 illustrated in FIG. 5B, a magnetic body 112 is provided between the end plate 108 and the sensor 106. The magnetic body 112 is fixed to the sensor side surface of the end plate 108. In this case, the end plate 108 may be a magnetic material or a non-magnetic material. Further, when the distance between the end plate 108 and the sensor 106 is long, by providing the magnetic body 112 separately, many lines of magnetic force L can be guided to the magnetic sensitive surface of the sensor 106.

  The rotation detection device 140 shown in FIG. 5C shows a case where there is no end plate. In this case, the magnetic body 112 is supported on the circuit board 34 via the support member 114 and is disposed above the sensor 106. The rotation detection device 140 configured in this way can also obtain the same operational effects as the rotation detection device 120 and the rotation detection device 130.

  As described above, in the rotation detection device illustrated in FIGS. 5A to 5C, a magnetic path having a high magnetic permeability is formed by disposing a magnetic body, and the magnetic flux of the sensor magnet 104 is efficiently transferred to the sensor 106. It becomes possible to lead to. As a result, even if the sensor magnet 104 fluctuates due to end play, a decrease in detection accuracy by the sensor 106 can be suppressed, and a smaller sensor magnet can be used. Further, the use of the metal housing 12 and the end plate 18 as the magnetic material that becomes the magnetic path eliminates the need for additional parts.

  Next, the range suitable for the sensor arrangement with respect to the sensor magnet will be described. FIG. 6 is a schematic diagram for explaining a region suitable for sensor arrangement. FIG. 6 shows a case where the magnetosensitive surface 106 a of the Hall element of the sensor 106 is provided on a plane including the axis Ax of the shaft 20. In the following, the arrangement of the sensor in a state where one of the magnetic poles is closest to the sensor in the rotating sensor magnet 104 will be described in detail.

  As a result of intensive studies by the inventors on a preferable range in which the sensor 106 is disposed, the inventors have conceived that it is preferable to arrange the sensor 106 within the following range.

  The region R1 preferable for the arrangement of the sensor 106 is a region outside the outer peripheral surface 104a of the sensor magnet 104, and is above (end) the extension line E1 of the magnetization vector M passing through the magnetization center C of the outer peripheral surface 104a of the sensor magnet 104. This is a square region on the plate 18 side. More specifically, the range in the direction parallel to the extension line E1 with respect to the outer peripheral surface 104a of the sensor magnet 104 may be set to a range in which sufficient lines of magnetic force reach the sensor 106. For example, the radial range r1 from the outer peripheral surface 104a of the sensor magnet 104 is 15 mm or less, preferably 12 mm or less, more preferably 6 mm or less. Within this range, the magnetic sensitivity characteristics, space efficiency, and productivity can be satisfied at a high level.

  On the other hand, the range of the region R1 in the direction parallel to the axis Ax is preferably up to a distance of 2t upward from the extension line E1 of the magnetization vector M, where t is the thickness of the sensor magnet 104. Within this range, the magnetic sensitivity characteristics, space efficiency, and productivity can be satisfied at a high level.

  Note that the region R1 does not need to include the entire magnetosensitive surface 106a of the sensor 106, and the sensor 106 may be disposed so as to include the center of the magnetosensitive surface 106a.

  Further, the region R2 that is more preferable for the arrangement of the sensor 106 is a region outside the outer peripheral surface 104a of the sensor magnet 104 and a square region centered on the extension line E2 passing through the upper end surface 104b of the sensor magnet 104. More specifically, the radial range r2 from the outer peripheral surface 104a of the sensor magnet 104 is preferably 3 mm or less.

  On the other hand, the range in the direction parallel to the axis Ax in the region R2 is preferably a range of ± y (total 2y) centering on the upper end surface 104b of the sensor magnet 104, where y is the distance of the end play of the motor. Within these ranges, the magnetic sensitivity characteristics, space efficiency, and productivity can be satisfied at a higher level.

  Next, the orientation of the magnetic sensitive surface 106a of the Hall element when the sensor 106 is disposed will be described. In each of the rotation detection devices described above, the angle α formed by the magnetosensitive surface 106a of the sensor 106 and the Ax of the shaft 20 is disposed in a range of 90 ° ± 45 °, more preferably 90 ° ± 10 °. Good. Thereby, the space efficiency at the time of arrange | positioning the sensor 106 improves, and the rotation detection apparatus whole can be reduced in diameter. In particular, if the sensor 106 is arranged so that the magnetosensitive surface 106a is orthogonal to the rotation axis Ax (α = 90 degrees), the rotation detection device can be thinned in the axial direction.

  And in the motor 10 shown in FIG.1 and FIG.2, the above-mentioned rotation detection apparatus is attached to the vicinity of the opening part 12a. Thereby, the motor 10 that is shorter in the axial direction or smaller in diameter can be realized.

  The sensor magnet 104 is preferably magnetized so that its magnetization vector M is orthogonal to the rotation axis Ax. Further, the magnetic flux density required on the magnetic sensitive surface 106a of the Hall element depends on the sensitivity of the mounted Hall element, but is preferably 1 mT or more. Therefore, the magnetic flux density at the magnetization center of the sensor magnet 104 may be set so as to realize these. The end plate 18 may be made of a ferromagnetic material. In addition to the Hall element, the sensor 106 may include a Hall IC in which a signal processing circuit that performs A / D conversion on the output of the Hall element, an arithmetic circuit, and the like are integrated. The sensor magnet 104 may be magnetized so that its magnetization vector is oblique or parallel to the rotation axis Ax. In this case, the arrangement of the sensor 106 and the direction of the magnetosensitive surface 106a may be set in consideration of the direction of the magnetization vector M.

  The motor 10 further includes a brush holder 16 and an end plate 18 provided in the opening 12a. The brush holder 16 has a first surface 16c on the housing 12 side that intersects the axial direction of the shaft 20, and a second surface 16d opposite to the first surface 16c. The second surface 16d is formed with a recess 16e. And the rotation detection apparatus 100 is arrange | positioned at the recessed part 16e. The end plate 18 includes a magnetic material, contacts the second surface 16 d of the brush holder 16, and is disposed in a region close to the rotation detection device 100. Thereby, the lines of magnetic force are efficiently guided to the sensor 106, and a stable output can be obtained.

  The motor 10 further includes a stator magnet 19 fixed to the inner peripheral surface of the housing 12 as shown in FIG. The rotation detection device 100 is configured such that the sensor 106 is opposite to the stator magnet 19 with the sensor magnet 104 interposed therebetween. Further, the sensor 106, the sensor magnet 104, and the stator magnet 19 are arranged in this order along the axial direction Ax of the shaft 20. Thereby, since the sensor magnet 104 is arranged between the sensor 106 and the stator magnet 19, the influence of the magnetic lines of force generated from the stator magnet 19 on the sensor 106 is suppressed.

  The rotation detection device described above can be used not only for the motor but also for various mechanisms that need to detect rotation. Further, the motor provided with the rotation detection device may be a brushless motor as well as a motor with a brush.

  As described above, the present invention has been described with reference to the above-described embodiment. However, the present invention is not limited to the above-described embodiment, and the present invention can be appropriately combined or replaced with the configuration of the embodiment. It is included in the present invention. In addition, it is possible to appropriately change the combination and processing order in the embodiment based on the knowledge of those skilled in the art and to add various modifications such as various design changes to the embodiment. The described embodiments can also be included in the scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 Motor, 12 Housing, 12a Opening part, 14 Rotor, 16 Brush holder, 16c 1st surface, 16d 2nd surface, 16e Recessed part, 18 End plate, 19 Stator magnet, 20 Shaft, 34 Circuit board, 100 Rotation detection apparatus, 104 sensor magnet, 104a outer peripheral surface, 104b upper end surface, 106 sensor, 106a magnetic sensitive surface, 106b outer surface, 108 end plate, 110 rotation detection device, 112 magnetic body, 114 support member, 120, 130, 140 rotation detection device.

Claims (5)

A rotation axis;
A sensor magnet fixed to the rotating shaft;
A sensor that detects a periodically changing magnetic field formed by the sensor magnet when the rotation shaft rotates,
The sensor is
It has an element that uses the Hall effect,
Arranged so that the magnetosensitive surface of the element is not perpendicular to the magnetization vector of the sensor magnet ,
A rotation detection device, wherein the rotation detection device is disposed outside the outer periphery of the sensor magnet as viewed from the axial direction of the rotation shaft and at a position not overlapping the sensor magnet as viewed from the radial direction .   A rotation detection device according to claim 1;
  A rotor fixed to the rotating shaft;
  A cylindrical housing that houses the rotor and has an opening at at least one of both ends in the axial direction;
  Further comprising a holder and an end plate provided in the opening,
  The holder has a first surface on the housing side that intersects the direction of the rotation axis, and a second surface opposite to the first surface,
  The second surface has a recess,
  The rotation detection device is disposed in the recess,
  The end plate is
  Including magnetic materials,
  Abutting on the second surface of the holder and disposed in a region close to the rotation detection device,
  A motor characterized by that. A stator magnet fixed to the inner peripheral surface of the housing;
  The rotation detection device is configured such that the sensor is on the opposite side of the stator magnet with the sensor magnet in between.
  The motor according to claim 2, wherein the sensor, the sensor magnet, and the stator magnet are arranged in this order along the rotation axis direction. A rotation detection device comprising: a rotation shaft; a sensor magnet fixed to the rotation shaft; and a sensor that detects a periodically changing magnetic field formed by the sensor magnet when the rotation shaft rotates.
A rotor fixed to the rotating shaft;
A cylindrical housing in which the rotor is housed and has openings in at least one of both axial ends;
And a holder and end plate which is provided in the opening,
The sensor has an element that uses the Hall effect, and is arranged so that the magnetosensitive surface of the element is not perpendicular to the magnetization vector of the sensor magnet,
The holder has a first surface on the housing side that intersects the direction of the rotation axis, and a second surface opposite to the first surface,
The second surface has a recess,
The rotation detection device is attached in the vicinity of the opening and is disposed in the recess.
The end plate includes a magnetic material, is in contact with the second surface of the holder, and is disposed in a region close to the rotation detection device.
Features and be makes the chromophore at the distal end over data that. A stator magnet fixed to the inner peripheral surface of the housing;
The rotation detection device is configured such that the sensor is on the opposite side of the stator magnet with the sensor magnet in between.
The motor according to claim 4 , wherein the sensor, the sensor magnet, and the stator magnet are arranged in this order along the rotation axis direction.

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