JP2013190338A - Rotation angle detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact rotation angle detection device capable of making rotation angle detection accuracy stable by arranging a magnetoelectric transducer at a position capable of reducing a curvature of a magnetic flux close to an end face of a magnet.SOLUTION: A rotation angle detection device includes: a magnet 13 attached to a rotation shaft 2; and a magnetoelectric unit 11 having a magnetoelectric transducer 23 disposed so as to face an end face 13a of the magnet 13, and a synthetic resin package 20 attached to a non-rotational structure 6 and accommodating the magnetoelectric transducer 23 therein. The end face 13a of the magnet 13 includes a spherical concavity 13b having a center C1 on an axis Y of the rotation shaft 2 so that a magnetic flux f of a magnetic field M facing to the end face 13a of the magnet 13 is flattened and drawn to a side of the magnet 13. An aligning bearing mechanism 32 enabling swing of the package 20 around the center C1 is disposed inside the spherical concavity 13b.

Description

  The present invention is a magnet attached to a rotating shaft and magnetized in a fixed direction perpendicular to the axis of the rotating shaft, and opposed to the end face of the magnet. The present invention relates to an improvement in a rotation angle detection device including a magnetoelectric conversion element that is detected in a conversion manner and a magnetoelectric conversion unit that is attached to a non-rotating structure and includes a synthetic resin package in which the magnetoelectric conversion element is installed.

  Such a rotation angle detecting device is already known as disclosed in, for example, Patent Document 1.

JP 2009-19926 A

  As shown in FIG. 3, the solid cylindrical magnet 013 in the conventional rotation angle detecting device has an end face 013 a facing the magnetoelectric conversion element 023 formed on a flat surface perpendicular to the axis Y of the rotary shaft 2. ing. In such a magnetic field M facing the end face 13a of the magnet 013, the curvature of the arcuate magnetic flux f decreases with increasing distance from the end face of the magnet 13, so that the end face of the magnet 013 can be made compact in order to make the rotation angle detector compact. When the magnetoelectric conversion element 023 is sufficiently close to 013a, even if a slight shift occurs in the positional relationship between the magnet and the magnetoelectric conversion element due to a change in environmental temperature or aging, the magnetism perceived by the magnetoelectric conversion element changes. Therefore, the detection accuracy of the rotation angle is affected. Therefore, conventionally, in order to stabilize the detection accuracy of the rotation angle, the magnetic sensing center C02 of the magnetoelectric conversion element 023 is disposed at a location relatively away from the end face 013a of the magnet 013 and where the curvature of the arcuate magnetic flux is relatively small. In this case, it is difficult to make the rotation angle detection device compact.

  The present invention has been made in view of such circumstances, and the curvature of the magnetic flux near the end face of the magnet can be reduced, and a magnetoelectric conversion element is disposed at that position, thereby achieving compact and stable rotation angle detection accuracy. It is an object of the present invention to provide a rotation angle detection device that can be used.

  In order to achieve the above object, the present invention provides a magnet attached to a rotating shaft and magnetized in a fixed direction perpendicular to the axis of the rotating shaft, and opposed to the end face of the magnet, and cooperates with the magnet. And a magnetoelectric conversion element for detecting the rotation angle of the rotary shaft in a magnetoelectric conversion manner, and a magnetoelectric conversion unit that is attached to a non-rotating structure and includes a synthetic resin package in which the magnetoelectric conversion element is installed. In the angle detection device, in order to flatten the magnetic flux of the magnetic field facing the end surface of the magnet and move it toward the magnet, a spherical recess having a center on the axis of the rotation axis is formed on the end surface of the magnet. The first feature is that an aligning bearing mechanism is provided on the inner side, which enables the magnet and the package to swing around the center. The structure corresponds to a bearing boss 6 of the throttle body 1 in an embodiment of the present invention described later.

  According to the present invention, in addition to the first feature, the aligning bearing mechanism includes a spherical concave portion and a spherical convex shaft formed on the package so as to be rotatably fitted in the spherical concave portion in all directions. The configuration is the second feature.

  Furthermore, in addition to the second feature, the present invention has a third feature in that a synthetic resin bearing layer is formed in the spherical recess.

  Furthermore, in addition to the first feature, the present invention has a fourth feature in that the magnet is molded and bonded to a synthetic resin rotor body that is attached by positioning and fitting to the end of the rotating shaft.

  According to the first feature of the present invention, the magnetic flux facing the end face of the magnet is displaced toward the magnet by the amount of the spherical recess formed on the end face of the magnet, and the curvature of the magnetic flux near the end face of the magnet is reduced. Decrease. Therefore, even if a magnetoelectric transducer is placed near the magnet in order to make the rotation angle detector more compact, the magnetoelectric transducer can sense magnetism at the location where the curvature of the magnetic flux is reduced. Even if there is a slight shift in the positional relationship between the magnet and the magnetoelectric transducer, the change in magnetism perceived by the magnetoelectric transducer is extremely small, and the rotational angle detection accuracy of the rotary shaft can be stabilized. It is possible to achieve both compactness and stability of rotation angle detection accuracy.

  In addition, a self-aligning bearing mechanism that enables the magnet and the package to swing around the center of the spherical recess is arranged inside the spherical recess of the magnet, so that the package can be assembled to a non-rotating structure. Then, the magnet and the magnetoelectric conversion element are automatically aligned by the action of the aligning bearing mechanism, the magnetoelectric conversion element can be held at a predetermined position with respect to the magnet, and the detection accuracy of the rotation angle of the rotary shaft can be stabilized. Can contribute to the development.

  According to the second feature of the present invention, the aligning bearing mechanism is constituted by a spherical concave portion of a magnet and a spherical convex shaft formed on the package so as to be fitted in the spherical concave portion so as to be rotatable in all directions. Thus, the aligning bearing mechanism can be configured without adding special members to the magnet and the package, and the number of parts and the number of assembling steps can be reduced, which can contribute to the cost reduction of the rotation angle detecting device.

  According to the third aspect of the present invention, since the synthetic resin bearing layer is formed in the spherical concave portion of the magnet, the friction coefficient between the synthetic resin bearing layer and the synthetic resin spherical convex shaft is small, and the bearing The rotational sliding of the spherical convex shaft with respect to the layer can be made smooth, and an increase in rotational resistance of the rotating shaft due to the sliding portion can be suppressed as much as possible.

  According to the fourth feature of the present invention, the magnet is molded and bonded to the synthetic resin rotor body that is positioned and fitted to the end of the rotating shaft, so that the magnet can be used without using a fixing member such as a screw. Can be coupled to the rotor body, and the number of parts and the number of assembly steps can be reduced, which can further contribute to the cost reduction of the rotation angle detection device.

The longitudinal cross-sectional view of the rotation angle detection apparatus which concerns on embodiment of this invention. The longitudinal cross-sectional view which shows the relationship between the magnetic field around the end surface of the magnet in the said rotation angle detection apparatus, and the position of a magnetoelectric conversion element. The longitudinal cross-sectional view which shows the relationship between the magnetic field around the end surface of the magnet in the conventional rotation angle detection apparatus, and the position of a magnetoelectric conversion element.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, in FIG. 1, reference numeral 1 denotes a throttle body constituting a part of an intake system of an engine, and has an intake passage 1a communicating with an intake port of the engine inside. A rotary shaft 2 disposed so as to cross the intake passage 1a is rotatably supported on the throttle body 1, and a butterfly throttle valve 3 for opening and closing the intake passage 1a is screwed to the rotary shaft 2. The A throttle lever for manually operating the rotary shaft 2 or an electric motor (not shown) for automatic operation is connected to one end of the rotary shaft 2, and the opening of the throttle valve 3 is connected to the other end. The rotation angle detecting device 5 of the present invention for detecting the above is connected.

  A pair of cylindrical bearing bosses 6 (only one of them is shown in the figure) projecting outward in the radial direction of the intake passage 1 a are formed on both side surfaces of the throttle body 1. In addition, a ball bearing 7 with a seal for rotatably supporting the rotary shaft 2 is mounted.

  The rotation angle detection device 5 includes a rotor 10 attached to the rotary shaft 2 in a bearing boss 6 outside the ball bearing 7 and a magnetoelectric conversion unit 11 attached to the bearing boss 6.

  The rotor 10 includes a rotor body 12 made of synthetic resin that is positioned and fitted to a small-diameter connecting short shaft 2a that the rotary shaft 2 has at the tip, and a magnet 13 that is embedded in the rotor body 12 at the time of molding. It consists of. The connecting short shaft 2a and the connecting hole 14 of the rotor main body 12 fitted to the connecting short shaft 2a have an oval cross section, and by fitting them together, the magnetic field of the throttle valve 3 and the magnet 13 is reduced. The rotating shaft 2 and the rotor 10 can be integrally rotated while maintaining a certain positional relationship with the direction.

  The magnet 13 is substantially solid and has a cylindrical shape and is arranged coaxially with the rotary shaft 2 and is magnetized in a certain direction perpendicular to the axis Y of the rotary shaft 2, thereby causing a diametrical line. N and S poles at opposite positions. A spherical recess 13b is formed on the end surface 13a of the magnet 13 facing the magnetoelectric conversion unit 11, an anchor hole 15 penetrating in the axial direction is formed in the center, and an annular anchor groove 16 is formed on the outer periphery. The

  On the other hand, the rotor body 12 made of synthetic resin is integrally connected to the connecting boss portion 12a having the connecting hole 14 and the upper end of the connecting boss portion 12a to fill the anchor hole 15 and the anchor groove 16. A cylindrical magnet support portion 12b that covers and holds the outer peripheral surface of the magnet 13 and a bearing layer 12c that is integrally connected to the upper end of the magnet support portion 12b that fills the anchor hole 15 and covers the spherical recess 13b. A grease reservoir 18 that is recessed toward the anchor hole 15 is formed at the center of the bearing layer 12c. As described above, the rotor body 12 made of synthetic resin fills the anchor hole 15 and the anchor groove 16 of the magnet 13, thereby enhancing the coupling strength with the magnet 13.

  The magnetoelectric conversion unit 11 includes a cylindrical package 20 made of an insulating synthetic resin, a coupler 21 and a mounting rod 22 that are integrally formed on the outer peripheral surface of the package 20 so as to protrude in different directions, and an internal package 20. A magneto-electric conversion element 23 provided, an electronic circuit board 24 that is also provided in the package 20 and linearizes the output voltage of the magneto-electric conversion element 23, and a coupler 21 is provided to extract the output signal of the electronic circuit board 24 to the outside. It comprises a plurality of signal terminals 25 held. As the magnetoelectric conversion element 23, for example, a Hall element is used.

  Thus, the package 20 is fitted at a predetermined position on the inner peripheral surface of the bearing boss 6, and the mounting rod 22 is fastened to the end surface of the bearing boss 6 by the bolt 27. In such a mounted state of the package 20, the magnetoelectric conversion element 23 is arranged such that its magnetic sensitive center C <b> 2 is at or near the center C <b> 1 of the spherical recess 13 b of the magnet 13.

  The package 20 is provided with a cylindrical magnet housing chamber 30 for housing the magnet support portion 12b of the rotor 10, and a spherical convex shaft 31 that is in contact with the bearing layer 12c so as to be rotatable in all directions is provided on the ceiling. It is integrally formed. The spherical concave portion 13b, the bearing layer 12c, and the spherical convex shaft 31 constitute an aligning bearing mechanism 32 that enables the magnet 13 and the package 20 to swing around the center C1 of the spherical concave portion 13b.

  A first seal member 33 that seals the inside of the bearing boss 6 in close contact with the inner peripheral surface of the bearing boss 6 is attached to the outer periphery of the package 20, and the inner peripheral surface of the package 20 is attached to the outer periphery of the rotor body 12. A second seal member 34 that seals the magnet housing chamber 30 closely is attached. The second sheet member 34 is contracted between a flange 35 formed on the outer periphery of the rotor main body 12 and a retaining ring 36 that is locked to the package 20 below the flange 35 so that the bearing layer 12c and the spherical convex shaft are provided. It also plays a role of urging the rotor 10 upward so that the 31 are pressed against each other.

  Next, the operation of this embodiment will be described.

  As shown in FIG. 2, the magnetoelectric conversion element 23 is disposed in a magnetic field M facing the end surface 13 a of the magnet 13 of the rotor 10, and generates a voltage corresponding to the magnetism sensed by the magnetic field M. Thus, when the magnet 13 of the rotor 10 that rotates together with the rotating shaft 2 changes the rotational position in accordance with the change in the opening degree of the throttle valve 3, the magnetoelectric conversion is caused by the change in the direction of the magnetic flux f of the magnet 13 with respect to the magnetoelectric conversion element 23. Since the amount of magnetism sensed by the element 23 changes, the voltage generated by the magnetoelectric conversion element 23 changes, and the voltage signal is output to the electronic control unit connected to the signal terminal 25, where the opening of the throttle valve 3 is determined. The calculated data is used for controlling the fuel injection amount and ignition timing of the engine.

  By the way, the magnet 13 of the rotor 10 is formed with a spherical recess 13b on the end surface 13a facing the magnetoelectric conversion element 23, so that the magnetic field M of the magnet 13 is displaced toward the magnet 13 by the amount of bending of the spherical recess 13b. As a result, the curvature of the arcuate magnetic flux f facing the end surface 13a of the magnet 13 is reduced, and in particular, the central portion of the magnetic flux f is flattened. Therefore, even if the magnetoelectric conversion element 23 is arranged at a position sufficiently close to the magnet 13 rather than the position of the conventional magnetoelectric conversion element 023 in order to make the rotation angle detection device 5 compact, the magnetoelectric conversion element 23 is Since the magnetism is sensed at the flattened portion of f, the magnetism sensed by the magnetoelectric conversion element 23 even if a slight shift occurs in the positional relationship between the magnet 13 and the magnetoelectric conversion element 23 due to a change in environmental temperature or aging. Therefore, the detection accuracy of the rotation angle of the rotary shaft 2 can be stabilized. Thus, both the compactness of the rotation angle detection device 5 and the stability of the rotation angle detection accuracy can be satisfied.

  In addition, an inner side of the spherical recess 13b of the magnet 13 is provided with an aligning bearing mechanism 32 that enables the magnet 13 and the package 20 to swing around the center C1 of the spherical recess 13b. When assembled to the bearing boss 6, the magnet 13 and the magnetoelectric conversion element 23 are automatically aligned by the action of the aligning bearing mechanism 32, and the magnetoelectric conversion element 23 can be held at a predetermined position with respect to the magnet 13. This can contribute to stabilization of the detection accuracy of the rotation angle of the rotating shaft 2.

  Furthermore, since the center C1 of the spherical recess 13b of the magnet 13 and the magnetosensitive center C2 of the magnetoelectric conversion element 23 are arranged so as to coincide with each other or close to each other, the magnet 13 and the magnetoelectric conversion are caused by a change in environmental temperature or aging. Even if a slight inclination occurs between the elements 23, the state of the magnetic field M where the magnetoelectric conversion element 23 is placed hardly changes, and the detection accuracy of the rotation angle of the rotating shaft 2 can be stabilized.

  The aligning bearing mechanism 32 is composed of a spherical concave portion 13b of the magnet 13 and a spherical convex shaft 31 formed on the package 20 so as to be fitted in the spherical concave portion 13b so as to be rotatable in all directions. The aligning bearing mechanism bearing mechanism 32 can be configured without adding a special member to the package 13 and the package 20, and the number of parts and the number of assembly steps can be reduced to reduce the cost of the rotation angle detection device 5. it can.

  Further, since the synthetic resin bearing layer 12c is formed in the spherical recess 13b of the magnet 13, the friction coefficient between the synthetic resin bearing layer 12c and the synthetic resin spherical convex shaft 31 is small, and the spherical convexity with respect to the bearing layer 12c is reduced. The rotational sliding of the shaft 31 can be made smooth, and an increase in rotational resistance of the rotational shaft 2 due to the sliding portion can be suppressed as much as possible. Further, since the grease reservoir 18 is provided in the bearing layer 12c, the friction coefficient is further reduced by the grease retained in the grease reservoir 18, and the rotation of the rotary shaft 2 is made smoother. Durability can be improved.

  Furthermore, since the magnet 13 is mold-coupled to the synthetic resin rotor body 12 attached to the end of the rotary shaft 2 by positioning and fitting, the magnet 13 is attached to the rotor body 12 without using a fixing member such as a screw. Thus, the number of parts and the number of assembly steps can be reduced, and the cost of the rotation angle detector 5 can be further reduced.

  The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, when molding the rotor body 12 made of synthetic resin, if the upper end portion of the magnet support portion 12b is connected to the outer peripheral portion of the bearing layer 12c, the anchor hole 15 can be eliminated and the magnet 10 can be made completely solid. it can. Further, the rotation angle detection device of the present invention is not limited to the detection of the opening degree of the throttle valve 3, but can be applied to rotation angle detection devices of various devices. The magnetoelectric conversion element 23 can also be constituted by an integrated magnetoelectric conversion element having a plurality of magnetoelectric conversion elements whose detection axes intersect each other.

f ... Magnetic flux C1 ... Spherical recess center C2 of magnet ... Sensitive center M of magnetoelectric transducer M ... Magnetic field Y ... Axis 2 of rotation axis ... Rotary shaft 5 ... Rotation angle detection device 12 ... Rotor body 12c ... Bearing layer 13 ... Magnet 13a ... End face 13b of magnet ... Spherical recess 20 of magnet .... Package 23 ... Magnetoelectric transducer 31 ... Spherical convex shaft 32 ... Centering bearing mechanism

Claims (4)

A magnet (13) attached to the rotating shaft (2) and magnetized in a certain direction perpendicular to the axis (Y) of the rotating shaft (2), and disposed opposite to the end surface (13a) of the magnet (13), The magnetoelectric transducer (23) for detecting the rotational angle of the rotary shaft (2) in a magnetoelectric manner in cooperation with the magnet (13) and the non-rotating structure (6) are attached to the magnetoelectric transducer ( 23) a rotation angle detecting device including a magnetoelectric conversion unit (11) made of a synthetic resin package (20),
In order to flatten the magnetic flux (f) of the magnetic field (M) facing the end face (13a) of the magnet (13) and bring it closer to the magnet (13) side, the end face (13a) of the magnet (13) has a rotating shaft ( 2) A spherical recess (13b) having a center (C1) is formed on the axis (Y) of (2), and the magnet (13) and package (about the center (C1) around the center (C1) are formed inside the spherical recess (13b). 20) A rotation angle detecting device characterized in that an aligning bearing mechanism (32) enabling mutual swinging is provided. The rotation angle detection device according to claim 1,
A spherical convex shaft (31) formed on the package (20) so that the aligning bearing mechanism (32) is fitted to the spherical concave portion (13b) and the spherical concave portion (13b) so as to be rotatable in all directions. And a rotation angle detection device. The rotation angle detection device according to claim 2,
A rotation angle detecting device characterized in that a synthetic resin bearing layer (12c) is formed in the spherical recess (13b). The rotation angle detection device according to claim 1,
A rotation angle detecting device characterized in that the magnet (10) is mold-coupled to a synthetic resin rotor main body (12) attached by positioning and fitting to an end of the rotating shaft (2).

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