JP2004239799A - Rotation angle detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle detecting device which is small in friction torque, excellent in capability of layout, and low in cost. <P>SOLUTION: A shaft 2 is provided with an actuating section 21 made of a magnetic substance, and to the actuating section 21 magnets 23a, 23b are attached with a spacing. Outside the magnets 23a, 23b, stator members 25a, 25b made of the magnetic substances and having opposed faces 26a, 26b being opposed to the magnets 23a, 23b with gaps are arranged. Between the stator members 25a, 25b a supporting block 27 of a nonmagnetic substance is arranged, and inside the supporting block 27 a Hall IC 28 and a pole piece 29 of a magnetic substance is attached. With the rotation of the shaft 2, each facing area S between the opposed faces 26a, 26b and the external perimeters 24a, 24b of the magnets 23a, 23b changes, and the density of magnetic flux passing the Hall IC 28 also changes in portion to the rotation angle of the shaft 2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation angle detection device that detects a rotation angle of an object to be detected, and more particularly to a technique that is effective when applied to a detection device for a throttle valve opening of an engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a non-contact type rotation angle detecting device, there is known a device in which a magnet is attached to an object to be detected and a change in magnetic flux is detected to detect the rotation angle of the object as disclosed in Japanese Patent No. 2,842,482. Have been.
[0003]
In the rotation angle detection device of FIG. 12, a rotor core 52 made of a magnetic material is attached to a shaft 51 for which rotation angle detection is required. A two-pole ring magnet 53 is fixed to the inner periphery of the rotor core 52. Outside the ring magnet 53, a stator core 54 is arranged coaxially with the shaft 51. The stator core 54 is formed of a magnetic material and includes two core pieces 54a and 54b having a semicircular cross section. A hall IC 56 is disposed in a gap 55 between the core pieces 54a and 54b.
[0004]
As shown in FIG. 12, the stator core 54 is a magnetic path of the magnetic flux of the ring magnet 53, and the Hall IC 56 outputs a voltage signal corresponding to the magnetic flux density linked. When the ring magnet 53 rotates together with the shaft 51, the amount of magnetic flux passing through the Hall IC 56 changes, and accordingly, the output signal from the Hall IC 56 also changes. This signal change corresponds to the rotation angle of the shaft 51, and changes almost linearly with the rotation. Thus, the rotation angle of the shaft 51 can be detected based on the signal from the Hall IC 56.
[0005]
On the other hand, in recent years, so-called electronically controlled throttle devices that drive a throttle valve of an engine by a motor have been widely used with the digitization of automobile parts. Here, the throttle valve is controlled by an electric signal instead of the mechanical operation by the conventional accelerator wire. The accelerator depression amount is electrically detected by a potentiometer or the like, and a motor is driven according to the value to open and close the throttle valve.
[0006]
In such an electronic control throttle device, the opening of the throttle valve is detected by a rotation angle detection device as shown in FIG. 12, but in addition to this, an outer rotor type detection device in which a magnet is arranged outside the stator core is also used. Many are used. For example, JP-A-2001-208510 and JP-A-2001-289610 disclose such an outer rotor type device. Here, when the shaft to which the throttle valve is fixed is driven by a motor, the rotation angle of the shaft, that is, the opening of the throttle valve is detected by the output signal of the Hall IC. Then, the operation of the motor is controlled based on the detected valve opening, and the valve opening is set according to the accelerator pedal depression amount, the engine load, and the like.
[0007]
[Patent Document 1] Japanese Patent No. 2842282
[Patent Document 2] JP-A-8-35809
[Patent Document 3] JP-A-2001-4315
[Patent Document 4] JP-A-2001-59702
[Patent Document 5] JP-A-2001-188003
[Patent Document 6] JP-A-2001-208510
[Patent Document 7] JP-A-2001-289609
[Patent Document 8] JP-A-2001-289610
[Patent Document 9] JP-A-2001-303979
[Patent Document 10] JP-A-2001-317909
[Patent Document 11] Japanese Patent Application No. 2002-21201
[Patent Document 12] Japanese Patent Application No. 2002-257723
[Patent Document 13] Japanese Patent Application No. 2002-258901
[0008]
[Problems to be solved by the invention]
However, in the rotation angle detecting device as shown in FIG. 12, as shown in FIG. 12, since the entire circumference of the stator core 54 forms a magnetic path, there is a problem that the rotational resistance (friction torque) of the shaft 51 increases. That is, since magnetic attraction is generated over the entire circumference between the stator core 54 and the ring magnet 53, the rotation angle detecting device of FIG. 12 increases the friction torque of the shaft 51 accordingly. When the friction torque increases, the output of the motor for driving the shaft must also be increased, which undesirably increases the size, price, and current consumption of the motor.
[0009]
Further, in the rotation angle detection device of FIG. 12, since the ring magnet 53 which is long in the axial direction is used, there is a problem that the amount of the magnet used is large and the cost is high. Furthermore, since the ring magnet 53 and the stator core 54 are arranged concentrically with the shaft 51 in the radial direction, the outer diameter of the entire device tends to be large, and there is a problem that the layout is restricted.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost rotation angle detection device that has a small friction torque and is excellent in layout.
[0011]
[Means for Solving the Problems]
The rotation angle detection device according to the present invention includes an operation unit formed of a magnetic material provided on a detection target whose rotation angle is required to be detected, a first magnet attached to the operation unit, and the first magnet. A second magnet having a polarity different from that of the first magnet, attached to the operating portion with an interval in the axial direction, and a second magnet arranged outside the first magnet and having a gap with the first magnet. A first stator member formed of a magnetic material and having an opposing surface that is spaced apart from the first magnet; and a first stator member that is axially spaced apart from the first stator member and that is spaced apart from the second magnet. A second stator member formed of a magnetic material and having a facing surface that is spaced apart from the first magnet, and extending from the first magnet to the second magnet via the first and second stator members; In the magnetic path And having a arranged magnetic sensor.
[0012]
According to the present invention, since the magnetic path is formed by the first and second magnets and the stator member having the opposing surface facing the magnet, the magnetic path around the operating portion can be reduced, and the magnetic path facing the magnet can be reduced. It is possible to reduce the magnetic attraction force acting on the surface. Therefore, the rotational resistance of the detected object can be reduced. In addition, since the rotation angle detection device can be configured with only one side region of the detection target, the amount of magnets can be reduced and the layout can be improved.
[0013]
In the rotation angle detecting device, the first and second magnets each have an outer peripheral surface having an arc-shaped cross section, and the opposed surfaces of the first and second stator members are respectively substantially equal to the respective outer peripheral surfaces. They may be opposed at regular intervals.
[0014]
Further, in the rotation angle detecting device, the first and second magnets each have an outer peripheral surface having an arc-shaped cross section, and the opposed surfaces of the first and second stator members respectively have the respective shapes. An arc portion facing the outer peripheral surface at a substantially constant interval may be provided, and an expanding portion formed at an end of the arc portion and increasing the distance between the outer peripheral surfaces toward the end may be provided. As a result, it is difficult to form a magnetic path from the magnet to the opposing surface via the operating portion, the output signal curve portion is reduced, and it is possible to obtain a signal output with a wider linear region from the magnetic detection element.
[0015]
Another rotation angle detection device of the present invention includes an operation unit made of a magnetic material provided on a detection target whose rotation angle is required to be detected, a magnet attached to the operation unit, and a magnet disposed outside the magnet. A first stator member formed of a magnetic material and having a facing surface facing the magnet at an interval; and a first stator member axially spaced from the first stator member; A second stator member formed of a magnetic material, comprising a facing surface facing the portion at an interval, and the magnet from the magnet via the first and second stator members and the operating portion. And a magnetic sensing element arranged in a magnetic path leading to
[0016]
According to the present invention, since the magnetic path is formed by the magnet and the stator member having the opposing surface facing the magnet and the operating portion, the magnetic path around the operating portion can be reduced, and the distance between the magnet and the opposing surface can be reduced. The magnetic attraction force acting on the surface can be reduced. Therefore, the rotational resistance of the detected object can be reduced. In addition, since the rotation angle detection device can be configured with only one side region of the detection target, layout characteristics are also improved. Further, since the magnetic path is formed by one magnet, the amount of magnet used can be further reduced.
[0017]
In the rotation angle detection device, an outer peripheral surface having an arc-shaped cross section is formed on the magnet, and the opposed surface of the first stator member is opposed to the outer peripheral surface at a substantially constant interval, and The opposed surface of the second stator member may be opposed to the operating portion at a substantially constant interval.
[0018]
In the rotation angle detecting device, the magnet may have an outer peripheral surface having an arc-shaped cross section, and may be opposed to the opposed surface of the first stator member at a substantially constant interval from the outer peripheral surface. An arcuate portion and an expanding portion formed at an end of the arcuate portion and increasing the distance between the outer peripheral surfaces toward the end may be provided. As a result, it is difficult to form a magnetic path from the magnet to the opposing surface via the operating portion, the output signal curve portion is reduced, and it is possible to obtain a signal output with a wider linear region from the magnetic detection element.
[0019]
Further, in the rotation angle detecting device, the magnet may be formed in a semi-cylindrical shape in which a center angle of the outer peripheral surface is formed to be approximately 180 °. As described above, by using a magnet having an outer peripheral surface with a partial arc cross section such as a semi-cylindrical shape, the amount of magnet used can be reduced by half with respect to a ring magnet having a circular cross section.
[0020]
On the other hand, another rotation angle detecting device according to the present invention includes an operating portion made of a magnetic material provided on a detection target whose rotation angle is required to be detected, And a magnet on which a second pole layer is formed, and a facing member disposed outside the first pole layer and facing the first pole layer at an interval. A first stator member, and a magnetic body comprising an opposing surface disposed at an axial distance from the first stator member and opposed to the second magnetic pole layer at an interval. A second stator member formed; and a magnetic sensing element disposed in a magnetic path from the first pole layer to the second pole layer via the first and second stator members. It is characterized by the following.
[0021]
According to the present invention, since the magnetic path is formed by the first and second magnetic pole layers and the stator member having the opposing surface facing each magnetic pole layer, the magnetic path around the operating portion can be reduced. Magnetic attraction acting between the magnet and the facing surface can be reduced. Therefore, the rotational resistance of the detected object can be reduced. Further, the rotation angle detecting device can be constituted only by one side region of the object to be detected, and since a plurality of magnetic pole layers are provided for one magnet, the dimension in the axial direction can be shortened and the layout property can be improved.
[0022]
In the rotation angle detecting device, an outer peripheral surface having a circular cross section is formed on the magnet, and the opposed surfaces of the first and second stator members are respectively opposed to the outer peripheral surfaces at substantially constant intervals. May be.
[0023]
In the rotation angle detection device, the magnet may have an outer peripheral surface having an arc-shaped cross section, and the opposing surfaces of the first and second stator members may have a substantially constant distance from the outer peripheral surface. An arcuate portion opposing at an interval and an expanding portion formed at an end of the arcuate portion and increasing the distance from the outer peripheral surface toward the end may be provided. As a result, it is difficult to form a magnetic path from the magnet to the opposing surface via the operating portion, the output signal curve portion is reduced, and it is possible to obtain a signal output with a wider linear region from the magnetic detection element.
[0024]
Further, in the rotation angle detecting device, the first and second magnetic pole layers may have one or two magnetic poles having different polarities of magnetic poles adjacent to each other.
[0025]
In addition, in the rotation angle detection device, the magnetic detection element may be disposed between the first and second stator members, and is formed of a non-magnetic material between the first and second stator members. A support member may be provided.
[0026]
Further, in the rotation angle detecting device, a pole member formed of a magnetic material and extending in at least one of the first and second stator members along an axial direction and having a front end portion facing the magnetic detection element. May be provided. Thereby, the magnetic flux of the magnet can be efficiently guided to the magnetic detection element, and the detection accuracy of the change in the magnetic flux can be improved. Further, by adjusting the gap between the tip of the pole member and the magnetic sensing element, the amount of magnetic flux flowing into the magnetic sensing element can be adjusted, and the sensitivity of the magnetic sensing element can be adjusted.
[0027]
On the other hand, in the rotation angle detection device, a rotation shaft to which an engine throttle valve is fixed may be used as the detection target.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a configuration of an electronically controlled throttle valve using a rotation angle detecting device according to Embodiment 1 of the present invention. The electronically controlled throttle valve of FIG. 1 is arranged in the intake passage of the engine, and controls the intake air amount of the engine by the opening degree of the throttle valve 1. The throttle valve 1 is fixed to a shaft 2 and is driven by a brushless motor 3 (hereinafter abbreviated as motor 3) via a speed reduction mechanism 15 including gears 11 to 14.
[0029]
The shaft 2 is rotatably supported by bearings 16a and 16b fixed to a metal housing 4. A cover 5 made of a synthetic resin is attached to an upper portion of the housing 4 in FIG. The substrate 30 is fixed inside the cover 5. A torsion coil spring 17 is attached to the gear 11 fixed to the shaft 2. The shaft 2 is urged in a predetermined rotational direction by the torsion coil spring 17, and the urging force causes the throttle valve 1 to automatically return to the fully closed position.
[0030]
At an end of the shaft 2, a rotation angle detection device 6 that detects an opening of the throttle valve 1 is provided. 2 is a plan view showing the configuration of the rotation angle detection device 6, and FIG. 3 is a side view of the rotation angle detection device of FIG. 2 when viewed from the X direction in FIG. In the rotation angle detection device 6, the shaft 2 to which the throttle valve 1 is attached is a detection target, and the rotation angle is detected. The shaft 2 is formed of a magnetic material, and a small-diameter portion 22 is provided as an operating portion 21 at an end thereof.
[0031]
Roof-shaped magnets 23a and 23b are fixed to the small-diameter portion 22 by bonding or the like at intervals in the axial direction. The magnets 23a and 23b are formed in a semi-cylindrical shape, and have outer peripheral surfaces 24a and 24b having a circular cross section. The outer peripheral surfaces 24a and 24b have a circumference with a central angle of 180 °. The magnets 23a and 23b are radially magnetized, and have different magnetic poles on the front side. The magnet 23a has an N pole on the surface, and the magnet 23b has an S pole on the surface. The magnets 23a and 23b only need to have arcuate outer peripheral surfaces 24a and 24b, and the inner peripheral surface does not necessarily have to be arcuate.
[0032]
Stator plates 25a, 25b (first and second stator members, hereinafter abbreviated as plates 25a, 25b) are arranged adjacent to the small diameter portion 22. The plates 25a and 25b are formed of a magnetic material, and are arranged at intervals in the axial direction in accordance with the magnets 23a and 23b. Opposite surfaces 26a, 26b facing the outer peripheral surfaces 24a, 24b of the magnets 23a, 23b are provided at the ends of the plates 25a, 25b. The opposing surfaces 26a and 26b are arranged outside the magnets 23a and 23b, and include an arc portion 48a and enlarged portions 48b formed at both ends of the arc portion 48a. The arc portion 48a has an air gap G substantially at a constant interval from the outer peripheral surfaces 24a and 24b of the magnets 23a and 23b. ₁ To face each other. On the other hand, the expanding portion 48b extends tangentially from the arc portion 48a, and the gap between the outer peripheral surfaces 24a and 24b increases toward the end.
[0033]
A support block (support member) 27 made of a non-magnetic material such as a synthetic resin is attached between the plates 25a and 25b. In the support block 27, a Hall IC (magnetic detection element) 28 is mounted on the plate 25b side. The Hall IC 28 is an IC in which a Hall element and a signal amplification circuit are integrated, and a linear output Hall IC is used. On the other hand, a pole piece (pole member) 29 formed of a magnetic material is attached to the plate 25a side of the support block 27. The pole piece 29 is formed in a cylindrical shape, and the tip thereof extends in the axial direction from the plate 25a and faces the end face of the Hall IC 28.
[0034]
The Hall IC 28 is disposed in a magnetic path M from the magnet 23a to the magnet 23b via the plates 25a and 25b. Here, as shown in FIG. 2, a magnetic path M is formed along the path of the magnet 23a → the opposing surface 26a → the plate 25a → the pole piece 29 → the Hall IC 28 → the plate 25b → the opposing surface 26b → the magnet 23b. The magnetic flux reaching the plate 25a from the magnet 23a is converged on the pole piece 29 and passes through the Hall IC 28 as shown in FIG. For this reason, the magnetic flux of the magnets 23a and 23b can be efficiently guided to the Hall IC 28, and the detection accuracy of the magnetic flux change is improved. Also, a gap G between the tip of the pole piece 29 and the Hall IC 28 ₂ Is adjusted, the amount of magnetic flux flowing into the Hall IC 28 can be adjusted, and the sensitivity of the Hall IC 28 can also be adjusted.
[0035]
As shown in FIG. 1, the motor 3 is a so-called inner rotor type brushless motor in which a rotor 32 is rotatably arranged inside a stator 31. The stator 31 includes a drive coil 33 and a stator core 34 around which the coil 33 is wound, and is fixed to the substrate 30. The stator core 34 is formed by laminating metal plates, and a winding is formed by winding a drive coil 33 around salient poles projecting from the inner peripheral side. The substrate 30 is provided with a Hall IC (not shown) for detecting the rotational position of the rotor 32. The Hall IC outputs a rotor position detection signal as the rotor 32 rotates.
[0036]
The rotor 32 includes a rotor shaft 35, a rotor core 36 fixed to the rotor shaft 35, and a rotor magnet 37 fixed to the outer periphery of the rotor core 36. The rotor magnet 37 is formed in a cylindrical shape, and N and S poles are arranged at equal intervals. The rotor shaft 35 is rotatably supported by bearings 38a and 38b. The bearing 38a is attached to the cover 5 and the bearing 38b is attached to a bracket 39 attached to the housing 4.
[0037]
On the rotor core 36, a columnar magnet mounting portion 36a and the gear 14 are formed. The gear 14 meshes with the gear 13 of the idle gear 18. The idle gear 18 is rotatably supported on a gear shaft 19 fixed to a bracket 39. The idle gear 18 has a gear 12 formed integrally with the gear 13, and the gear 12 is engaged with the gear 11 fixed to the shaft 2. Thereby, the rotation of the rotor 32 in the motor 3 is reduced and transmitted to the shaft 2.
[0038]
Next, the operation of the rotation angle detecting device 6 in such an electronically controlled throttle valve will be described. In the electronically controlled throttle valve, the rotation angle detecting device 6 is set to be in the state shown in FIG. 3 (θ = 0 °) when the throttle valve 1 is in the fully closed state. The shaft 2 operates between θ = 0 ° and 90 ° in accordance with the full closing and full opening of the throttle valve 1, and the magnetic flux density of the magnetic path M changes with the rotation of the shaft 2. Based on the change in the output voltage of the Hall IC 28 due to the change in the magnetic flux density, the rotation angle of the shaft 2, that is, the opening of the throttle valve 1 is detected. The rotation angle detection device 6 has a specification capable of sensing the rotation angle of the shaft 2 by 180 °, and detects the opening of the throttle valve 1 using a part of the sensing area.
[0039]
In the rotation angle detection device 6, the facing area S between the facing surfaces 26a, 26b and the outer peripheral surfaces 24a, 24b of the magnets 23a, 23b changes with the rotation of the shaft 2. FIG. 4 shows that the shaft 2 is shifted from the state shown in FIG. ₁ It is an explanatory view showing the state rotated only. As shown in FIG. 4, when the shaft 2 rotates, the portion below the outer peripheral surface 24a is separated from the opposing surface 26a, and a portion that does not oppose the outer peripheral surface 24a is formed on the opposing surface 26a. That is, the facing area S decreases due to the rotation of the shaft 2. Similarly, on the magnet 23b side, the facing area between the facing surface 26b and the outer peripheral surface 24b of the magnet 23b decreases.
[0040]
In the magnetic path M, magnetic flux flows from the magnet 23a to the plate 25a via the facing surface 26a. Therefore, when the opposing area S between the opposing surface 26a and the outer peripheral surface 24a decreases, the magnetic flux flowing from the magnet 23a to the plate 25a also decreases. At this time, the rate of decrease in magnetic flux is proportional to the decrease in the facing area S. That is, as the shaft 2 rotates, the density of the magnetic flux passing through the Hall IC 28 located in the magnetic path M also changes linearly in proportion to the rotation angle. Then, based on the change in the magnetic flux, the Hall IC 28 outputs a linear voltage signal proportional to the rotation angle of the shaft 2.
[0041]
In the magnets 23a and 23b, a magnetic path is formed between the magnetic poles on the shaft 21 side and the opposing surfaces 26a and 26b via the shaft 21, and a signal from the Hall IC 28 is slightly curved near θ = 0 °. Tend to be. Therefore, in the rotation angle detecting device 6, an enlarged portion 48b is provided at an end of the facing surfaces 26a, 26b, and the distance (air gap) between the facing surfaces 26a, 26b and the shaft 21 is further increased. For this reason, the above-mentioned magnetic path via the shaft 21 is hardly formed, and the curved portion of the output signal can be reduced, and a signal output with a wider linear area can be obtained from the Hall IC 28.
[0042]
The output signal from the Hall IC 28 thus obtained is sent to the control device (CPU). The output of the Hall IC 28 is stored in the control device in the form of a table or the like in association with the rotation angle of the shaft 2. The control device calculates the rotation angle of the shaft 2, that is, the opening of the throttle valve 1, based on the output change of the Hall IC 28 with reference to a table or the like.
[0043]
As described above, in the rotation angle detecting device 6, since the magnetic path M is formed by the plates 25a and 25b provided with the semi-cylindrical magnets 23a and 23b and the semi-circular opposed surfaces 26a and 26b, the related art has been described with reference to FIG. As described above, the magnetic path formed over the entire circumference of the shaft 2 is reduced to only a half circumference of the shaft 2. For this reason, the magnetic attraction force acting between the magnets 23a and 23b and the opposing surfaces 26a and 26b is also equivalent to a half turn, and the friction torque of the shaft 2 can be reduced. In addition, since the rotation angle detecting device 6 can be constituted only by one side region of the shaft 2 using the semi-cylindrical magnets 23a and 23b, the amount of magnet used can be reduced and the device is arranged over the entire circumference. The layout property is also improved as compared with the rotation angle detecting device.
[0044]
Further, since the plates 25a and 25b can be made of magnetic thin plates, the axial lengths of the magnets 23a and 23b facing them can also be shortened. Therefore, also in this respect, the amount of magnets used can be reduced, and the cost and weight of parts can be reduced.
[0045]
In the rotation angle detecting device 6, the magnet 23b can be omitted. FIG. 5 is a plan view showing a configuration of a modification in which the magnet 23b is omitted in the rotation angle detection device 6. Here, the magnetic path M is formed between the N pole and the S pole on the front and back of the magnet 23a. That is, a magnetic path M is formed in a path of the magnet 23a (front N pole) → opposed surface 26a → plate 25a → pole piece 29 → hall IC 28 → plate 25b → opposed surface 26b → small diameter portion 22 → magnet 23a (back surface S pole). Is done. Thus, in the apparatus of FIG. 5, the magnet 23b is omitted, and the amount of magnet used can be further reduced. However, the configuration of FIG. 2 is more advantageous in securing the amount of magnetic flux.
[0046]
(Embodiment 2)
FIG. 6 is a plan view showing a configuration of a rotation angle detection device 41 according to a second embodiment of the present invention, and FIG. 7 is a side view of the rotation angle detection device of FIG. 6 as viewed in FIG. In the following embodiments, parts other than the rotation angle detecting device are the same as those of the electronically controlled throttle valve of the first embodiment, and therefore, the description thereof will be omitted. Further, the same reference numerals are used for the same parts and members as in the first embodiment.
[0047]
In the rotation angle detecting device 41, a cylindrical magnet 42 is attached to the small-diameter portion 22 of the operating portion 21. The magnet 42 has two pole layers 43a and 43b (first and second pole layers) in the axial direction. Each of the magnetic pole layers 43a and 43b has two magnetic poles having adjacent magnetic poles having different polarities. That is, each of the magnetic pole layers 43a and 43b is magnetized to two poles in the circumferential direction, and the magnetic poles are arranged between the magnetic pole layers 43a and 43b such that the polarities of the adjacent magnetic pole layers are different. .
[0048]
Plates 25a and 25b are provided outside the magnet 42. An outer peripheral surface 44a of the pole layer 43a is provided on the opposing surface 26a of the plate 25a with an air gap G having substantially constant intervals. ₁ To face each other. On the other hand, the outer peripheral surface 44b of the pole layer 43b is formed on the opposing surface 26b of the plate 25b with the air gap G having a substantially constant interval. ₁ To face each other. A magnetic path M is formed between the magnetic pole layers 43a and 43b in a path of the magnetic pole layer 43a → the opposing surface 26a → the plate 25a → the pole piece 29 → the Hall IC 28 → the plate 25b → the opposing surface 26b → the magnetic pole layer 43b.
[0049]
In the rotation angle detecting device 41, the polarity of the magnet 42 facing the facing surfaces 26a, 26b changes with the rotation of the shaft 2. FIG. 8 shows that the shaft 2 is shifted from the state of FIG. ₁ It is an explanatory view showing the state rotated only. As shown in FIG. 8, when the shaft 2 rotates, the lower part of the N pole of the magnetic pole layer 43a is separated from the opposing surface 26a, and the S pole of the magnetic pole layer 43a faces the upper part of the opposing surface 26a. Then, a part of the magnetic flux from the N pole of the pole layer 43a toward the plate 25b via the plate 25a goes to the S pole of the pole layer 43a itself in the plate 25a. That is, magnetic fluxes from magnetic poles of different polarities having the same area facing the facing surface 26a form a closed loop in the plate 25a, and become a balanced component. Then, an unbalanced component other than the balanced component flows through the magnetic path M, and the amount of magnetic flux flowing through the magnetic path M is reduced by that amount.
[0050]
Also in the rotation angle detection device 41, the density of the magnetic flux passing through the Hall IC 28 changes linearly in proportion to the rotation angle of the shaft 2. A linear voltage signal proportional to the rotation angle of the shaft 2 is output from the Hall IC 28, and the rotation angle of the shaft 2 is calculated based on this signal. At this time, since the rotation angle detecting device 41 actively forms the unbalanced component, the change in the amount of magnetic flux of the magnetic path M according to the rotation angle is larger than that of the rotation angle detecting device 6 described above. Therefore, the sensitivity to the rotation angle can be further increased, and the angle detection accuracy is improved. Since the rotation angle detection device 41 uses the cylindrical magnet 42, the rotation angle of the shaft 2 can be detected by 360 °.
[0051]
In the rotation angle detecting device 41, each of the magnetic pole layers 43a and 43b of the magnet 42 may have a single pole configuration. FIG. 9 is a plan view showing a configuration of a modification in which the magnetic pole layers 43a and 43b have a single pole configuration in the rotation angle detection device 41. Here, the magnet 42 is formed in a semi-cylindrical shape, and the magnetic pole layer 43a has only the N pole on the outer peripheral surface 44a, and the magnetic pole layer 43b has only the S pole on the outer peripheral surface 44b. That is, in the rotation angle detection device 6 in FIG. 2, the magnets 23a and 23b are integrated, and the rotation angle detection device 45 in FIG. 9 is a combined form of the first and second embodiments.
[0052]
(Embodiment 3)
FIG. 10 is a side view showing a configuration of a rotation angle detection device 46 according to the third embodiment of the present invention. In the above-described embodiment, the configuration is shown in which the magnet 23a and the like are directly attached to the shaft 2 in the operating portion 21, but a core 47 made of a magnetic material may be attached to the operating portion 21 and the magnet may be attached outside the core 47. . In this case, since the magnetic path can be formed by the core 47, the rotation angle detecting device can be used even when the shaft 2 is not formed of a magnetic material. Although FIG. 10 shows a configuration in which the core 47 is attached to the shaft 2 in the rotation angle detection device 6 of FIGS. 2 and 3, the rotation angle detection devices 41 and 45 may have the same configuration. is there.
[0053]
The present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention.
For example, in the first embodiment described above, a configuration using a semi-cylindrical magnet having a center angle of the outer peripheral surface of 180 ° has been described. However, the center angle is not limited to 180 °, and may be determined according to the detection angle range. It can be changed as appropriate. Also, the angle of the facing surface can be appropriately changed according to the angle.
[0054]
In addition, in the above-described embodiment, an example in which the rotation angle detection device according to the present invention is used for detecting the opening degree of the electronically controlled throttle valve has been described. It is widely applicable to rotation angle detection of a rotating body.
[0055]
【The invention's effect】
According to the rotation angle detecting device of the present invention, the first and second magnets are attached to the operating portion made of the magnetic material provided on the detected object, and the opposing surface that faces each magnet at an interval in the axial direction. First and second stator members made of a magnetic material provided with a magnetic member are disposed in a magnetic path from the first magnet to the second magnet via the first and second stator members. Therefore, the magnetic path around the operating portion can be reduced, and the magnetic attraction acting between the magnet and the facing surface can be reduced. Therefore, the rotational resistance of the detected object can be reduced. In addition, the rotation angle detection device can be configured with only one side region of the detection target, and it is possible to reduce the amount of magnets and improve the layout.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a configuration of an electronically controlled throttle valve using a rotation angle detection device according to a first embodiment of the present invention.
FIG. 2 is a plan view showing a configuration of a rotation angle detection device according to the first embodiment of the present invention.
FIG. 3 is a side view of the rotation angle detection device of FIG. 2 when viewed from the X direction of FIG. 2;
FIG. 4 is an explanatory view showing a state in which the shaft has been rotated by an angle θ1 from the state in FIG. 3;
FIG. 5 is a plan view showing a configuration of a modification in which one magnet is omitted in the rotation angle detecting device of FIG. 2;
FIG. 6 is a plan view illustrating a configuration of a rotation angle detection device according to a second embodiment of the present invention.
FIG. 7 is a side view of the rotation angle detection device of FIG. 6 viewed in the same manner as FIG. 3;
FIG. 8 shows a state in which the shaft is shifted from the state shown in FIG. ₁ It is an explanatory view showing the state rotated only.
FIG. 9 is a plan view showing a configuration of a modification in which each magnetic pole layer has a single pole configuration in the rotation angle detection device of FIG. 6;
FIG. 10 is a side view illustrating a configuration of a rotation angle detection device according to a third embodiment of the present invention.
FIG. 11 is an explanatory diagram showing a configuration of a conventional rotation angle detection device.
[Explanation of symbols]
1 Throttle valve
2 shaft
3 brushless motor
4 Housing
5 Cover
6 Rotation angle detector
11-14 gears
15 Reduction mechanism
16a, 16b bearing
17 Torsion coil spring
18 Idle gear
19 Gear shaft
21 Working part
22 Small diameter part
23a, 23b magnet
24a, 24b outer peripheral surface
25a, 25a Stator plate (stator member)
26a, 26b Opposing surface
27 Support block (support member)
28 Hall IC (magnetic detection element)
29 Pole piece (pole member)
30 substrates
31 Stator
32 rotor
33 drive coil
34 Stator core
35 Rotor shaft
36 rotor core
36a Magnet mounting part
37 Rotor magnet
38a, 38b bearing
39 bracket
41 Rotation angle detector
42 magnet
43a, 43b magnetic pole layer
44a, 44b Outer peripheral surface
45 Rotation angle detector
46 Rotation angle detector
47 core
48a Arc section
48b Expanding part
51 shaft
52 rotor core
53 ring magnet
54 Stator core
54a core piece
55 gap
56 Hall IC
G ₁ Air gap
G ₂ gap
M magnetic path
S Opposing area

Claims (15)

An actuating unit made of a magnetic material provided on the object to be detected for which detection of the rotation angle is required,
A first magnet attached to the operating portion;
A second magnet that is attached to the operating unit at an axial distance from the first magnet and has a polarity different from that of the first magnet;
A first stator member formed of a magnetic material, having a facing surface disposed outside the first magnet and facing the first magnet at an interval;
A second stator member formed of a magnetic material, comprising: a second stator member that is disposed at an axial distance from the first stator member and has an opposing surface that faces the second magnet at an interval;
A rotation angle detection device, comprising: a magnetic detection element disposed in a magnetic path from the first magnet to the second magnet via the first and second stator members. 2. The rotation angle detecting device according to claim 1, wherein the first and second magnets have an outer peripheral surface having an arc-shaped cross section, and the opposing surfaces of the first and second stator members each have the outer peripheral surface. A rotation angle detection device characterized by being opposed to a surface at a substantially constant interval. 2. The rotation angle detecting device according to claim 1, wherein the first and second magnets have an outer peripheral surface having an arc-shaped cross section, and the opposing surfaces of the first and second stator members are respectively formed by the respective magnets. 3. A rotating portion having an arc portion facing the outer peripheral surface at a substantially constant interval, and an expanding portion formed at an end of the arc portion and increasing the interval between the outer peripheral surfaces toward the end; Angle detector. An actuating unit made of a magnetic material provided on the object to be detected for which detection of the rotation angle is required,
A magnet attached to the operating portion,
A first stator member formed of a magnetic material, comprising a facing surface disposed outside the magnet and facing the magnet at an interval;
A second stator member formed of a magnetic material, comprising a facing surface that is disposed at an axial distance from the first stator member and faces the operating portion at a distance;
A rotation angle detection device comprising: a first and a second stator member from the magnet; and a magnetic detection element disposed in a magnetic path from the magnet to the magnet via the operating portion. 5. The rotation angle detecting device according to claim 4, wherein the magnet has an outer peripheral surface having an arc-shaped cross section, and the opposed surface of the first stator member faces the outer peripheral surface at a substantially constant interval. A rotation angle detecting device, wherein the opposed surface of the second stator member faces the operating portion at a substantially constant interval. 5. The rotation angle detecting device according to claim 4, wherein the magnet has an outer peripheral surface having an arc-shaped cross section, and the facing surface of the first stator member faces the outer peripheral surface at a substantially constant interval. A rotation angle detecting device, comprising: a circular arc portion; The rotation angle detecting device according to any one of claims 2, 3, 5, and 6, wherein the magnet has a semi-cylindrical shape in which a center angle of the outer peripheral surface is formed at approximately 180 °. Rotation angle detector. An actuating unit made of a magnetic material provided on the object to be detected for which detection of the rotation angle is required,
A magnet attached to the operating portion and having first and second pole layers formed adjacent to each other in the axial direction;
A first stator member formed of a magnetic material, comprising a facing surface disposed outside the first pole layer and facing the first pole layer at an interval;
A second stator member formed of a magnetic material, comprising a facing surface that is arranged at an axial distance from the first stator member and faces the second magnetic pole layer at an interval; ,
A rotation angle detection device, comprising: a magnetic detection element disposed in a magnetic path from the first pole layer to the second pole layer via the first and second stator members. 9. The rotation angle detecting device according to claim 8, wherein the magnet has an outer peripheral surface having a circular cross section, and the opposing surfaces of the first and second stator members are respectively spaced apart from the outer peripheral surface at a substantially constant interval. A rotation angle detection device characterized by being opposed to each other. 9. The rotation angle detecting device according to claim 8, wherein the magnet has an outer peripheral surface having an arc-shaped cross section, and the opposing surfaces of the first and second stator members each have a substantially constant interval with the outer peripheral surface. A rotation angle detecting device, comprising: an arc portion facing away from the arc portion; and an expanding portion formed at an end of the arc portion and increasing a distance from the outer peripheral surface toward an end. The rotation angle detecting device according to any one of claims 8 to 10, wherein the first and second magnetic pole layers each have one or two magnetic poles having adjacent magnetic poles having different polarities. A rotation angle detection device characterized by the above-mentioned. The rotation angle detection device according to any one of claims 1 to 11, wherein the magnetic detection element is disposed between the first and second stator members. The rotation angle detecting device according to claim 1, wherein a support member made of a non-magnetic material is provided between the first and second stator members. . The rotation angle detecting device according to any one of claims 1 to 13, wherein at least one of the first and second stator members extends in an axial direction, and a tip portion thereof faces the magnetic detection element. And a pole member formed of a magnetic material. The rotation angle detection device according to any one of claims 1 to 14, wherein the object to be detected is a rotation shaft to which a throttle valve of an engine is fixed.

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