Rotation angle detection device

Abstract

The rotation angle detection device comprises: a shaft (15) connected to a valve body; a gear (14) connected to the shaft and causing the valve body to rotate by the rotation of the shaft; a magnetic field generating unit (21) arranged on the gear side and generating a magnetic field; a magnetic fixing metal component (25) arranged at a position covering at least a portion of the magnetic field generating unit and used to fix the gear to the shaft; and a magnetic detection element (24) arranged on an extension line of the shaft and detecting the magnetic flux density of the magnetic field rotating with the rotation of the gear.

Description

[0001] Cross-references of related applications

[0002] This application claims priority based on Japanese Patent Application No. 2019-120743 filed on June 28, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a rotation angle detection device. Background Art

[0004] Japanese Patent Publication No. 2014-151643 discloses a rotation angle detection device that detects the rotation angle of a valve gear driven by an electric actuator. The rotation angle detection device includes: a magnetic circuit portion that rotates together with the valve gear; and a magnetic detection element such as a Hall element that detects the change in magnetic flux caused by the rotation of the magnetic circuit portion. When the valve gear is rotated, the magnetic flux circuit portion also rotates, and the angle between the magnetic flux formed by the magnetic flux circuit portion and the magnetic detection element changes. As a result, the magnetic detection element can detect the change in the rotation angle as a change in the magnetic field strength. Summary of the invention

[0005] However, for such a rotation angle detection device, the magnetic detection element may be affected by the change of the external magnetic field, in which case the detection accuracy of the rotation angle of the valve gear may be reduced. For example, if a component that generates a magnetic field, such as a motor, or a component that generates a magnetic field by energizing a wire or coil is arranged near the rotation angle detection device, the detection accuracy of the rotation angle detection device may be affected by the magnetic field generated by such an external device.

[0006] According to one technical solution of the present invention, a rotation angle detection device for detecting the rotation angle of a valve body is provided. The rotation angle detection device comprises: a shaft connected to the valve body; a gear connected to the shaft, and the valve body is rotated by the rotation of the shaft; a magnetic field generating part arranged on the gear side to generate a magnetic field; a magnetic fixing metal part arranged at a position covering at least a part of the magnetic field generating part, and used to fix the gear on the shaft; and a magnetic detection element arranged on the extension line of the shaft, and detecting the magnetic flux density of the magnetic field rotating with the rotation of the gear. According to the technical solution, since the fixing metal part is a magnetic body, it is possible to shield at least a part of the magnetic field from the outside. As a result, even if a part such as a motor, wiring, coil, etc. that generates a magnetic field that becomes interference to the rotation angle detection device is arranged near the rotation angle detection device, since the fixing metal part shields at least a part of the interference magnetic field, the influence of the interference magnetic field on the magnetic detection element can be suppressed, and the detection accuracy can be suppressed from being deteriorated. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is an explanatory diagram showing a schematic structure of an electronically controlled throttle valve equipped with a rotation angle detection device.

[0008] Figure 2 This is an explanatory diagram showing a schematic structure of an electronically controlled throttle valve equipped with a rotation angle detection device.

[0009] Figure 3 It is an explanatory diagram showing the structure of a gear.

[0010] Figure 4 It is an explanatory diagram showing the structure of a magnetic circuit.

[0011] Figure 5 It is an explanatory diagram showing the fixing metal parts.

[0012] Figure 6 It is a graph showing the magnitude of the influence of disturbance in the comparative example and the present embodiment.

[0013] Figure 7 It is an explanatory diagram showing other fixing metal parts.

[0014] Figure 8 It is an explanatory diagram showing other fixing metal parts.

[0015] Fig. 9 It is an explanatory diagram showing other fixing metal parts.

[0016] Fig.10 It is an explanatory diagram showing other fixing metal parts.

[0017] Fig.11 It is an explanatory diagram showing other fixing metal parts.

[0018] Fig.12 It is an explanatory diagram showing other fixing metal parts.

[0019] Fig.13 It means use Fig.12 A graph showing the output error when fixing with metal parts is shown.

[0020] Fig.14 It is an explanatory diagram showing caulking and fixing.

[0021] Fig.15 It is an explanatory diagram showing the structure of a magnetic circuit according to the second embodiment.

[0022] Fig.16 It is an explanatory diagram showing an example of the shape of a magnet. DETAILED DESCRIPTION

[0023] ·First embodiment:

[0024] Figure 1 , Figure 2 The electronically controlled throttle valve 10 is shown, which is provided with a rotation angle detection device for detecting the rotation angle of a valve body 16. The electronically controlled throttle valve 10 controls the amount of intake air to the engine of a vehicle by rotating the valve body 16 provided in an intake passage 17. The electronically controlled throttle valve 10 includes a motor 11, gears 12, 13, 14, a shaft 15, a valve body 16, an intake passage 17, a housing 18, a housing cover 19, a spring 20, a magnetic field generating unit 21, a magnetic detection element 24, and a fixing metal member 25.

[0025] An intake passage 17 is provided inside the housing 18. A valve body 16 for controlling the flow of air in the intake passage 17 is provided in the intake passage 17. The valve body 16 is, for example, a butterfly valve and is rotatably supported by a shaft 15. The shaft 15 is formed of metal, and a resin gear 14 is fixed to one end thereof. The shaft 15 and the gear 14 are fixed using a magnetic fixing metal member 25, and the magnetic fixing metal member 25 is insert-molded on the gear 14. The gear 14 is connected to the motor 11 via the gears 13 and 12. The motor 11 is controlled by an ECU (not shown) that controls the operation of the engine (not shown). When the accelerator pedal (not shown) is stepped on, the ECU drives the motor 11 according to the amount of stepping, and rotates the gears 12, 13, 14 and the shaft 15 in sequence to rotate the valve body 16, thereby adjusting the amount of air intake to the engine and increasing or decreasing the output of the engine. The spring 20 is a torsion spring, and generates a force for the valve body to bias the valve body 16 in the direction of opening or closing the valve. The spring 20 may be a spring of another type such as a coil spring, or may have a structure that includes a coil spring that urges the valve body 16 in the valve closing direction or a coil spring that urges the valve body 16 in the valve opening direction.

[0026] The ECU uses a magnetic field generating unit 21 and a magnetic detection element 24 to detect to what extent the valve body 16 rotates and opens. A magnetic field generating unit 21 that generates a magnetic field is integrally formed on the gear 14. A magnetic detection element 24 is arranged on the housing cover 19. The magnetic detection element 24 is arranged to be located on the inner side of the magnetic field generating unit 21 and on the extension line of the shaft 15, and to detect the magnetic flux density of the magnetic field in a predetermined detection direction in the magnetic field generated by the magnetic field generating unit 21. In addition, the magnetic detection element 24 is preferably arranged at the rotation center of the gear 14. The magnetic detection element 24 is composed of a Hall element, for example. An MR element can also be used instead of a Hall element. In addition, the magnetic detection element 24 can also be a structure that detects magnetic flux density in two directions. For example, it can also be configured in a manner that the detection directions of the magnetic flux densities of the two magnetic detection elements intersect. In this case, the two magnetic detection elements can be housed in one package or in separate packages. The fixing metal component 25 is integrally formed with the gear 14 to fix the shaft 15 and the gear. In addition, the fixing metal part 25 is formed of a magnetic body such as a cold-rolled steel sheet (SPCC), shielding the magnetic field from the outside to prevent the magnetic field from affecting the magnetic field generating part 21. In addition to being formed of a ferromagnetic material such as a cold-rolled steel sheet, the fixing metal part 25 can also be formed of a soft magnetic material such as a silicon steel sheet or a ferrite core. Forming the fixing metal part 25 from a cold-rolled steel sheet has the advantages of being easier to obtain the material, good processability in punching and press processing, and being able to reduce costs.

[0027] The gear 14 rotates around the rotation center O. A fixing metal member 25 for fixing the shaft 15 is integrally formed around the rotation center O. When the gear 14 is viewed from the axial direction of the rotation center O, the magnetic field generating portion 21 is arranged so as to overlap with the outer periphery of the fixing metal member 25. In addition, when the gear 14 is viewed from the axial direction of the rotation center O, the magnetic field generating portion 21 may not overlap with the outer periphery of the fixing metal member 25. The magnetic field generating portion 21 is also integrally formed on the gear 14.

[0028] like Figure 3 , Figure 4 As shown, the magnetic field generating unit 21 includes a pair of magnets 22 and a pair of yokes 23. The xyz direction is defined for the purpose of explaining the shape and arrangement direction of each part of the magnetic field generating unit 21 and the shape and arrangement direction of the fixing metal member 25 described later. Figure 4As shown, the arrangement direction of a pair of magnets 22 is assumed to be the x direction, the direction in which a pair of yokes 23 face each other is assumed to be the y direction, and the direction perpendicular to the x and y directions is assumed to be the z direction. The y direction is consistent with the direction By of the magnetic field lines at the center of the magnetic field generating part 21. In addition, the z direction is consistent with the direction along the axial direction of the shaft 15. Each yoke 23 has a roughly arc shape, and by clamping the magnet 22 with the ends of two yokes 23 arranged facing each other, the magnetic field generating part 21 becomes a roughly cylindrical shape consisting of a pair of magnets 22 and a pair of yokes 23. At this time, the N poles of the two magnets are respectively connected to the ends of one yoke 23, and the S poles of the two magnets are respectively connected to the ends of the other yoke 23. Therefore, as in Figure 4 As indicated by the dotted lines in the figure, the magnetic lines of force generated by the two magnets 22 pass through the inside of each yoke 23 and are directed toward the center of the opposing yoke from the center of the arc direction of each yoke 23. The magnetic lines of force generated by the pair of magnets are plane-symmetrical with the yz plane passing through the axis 15 as the symmetry plane. In addition, the x direction and the y direction are defined by the magnetic field generating unit 21. Figure 4 The upper part of the figure shows the reference position when the direction By of the magnetic field lines from one yoke 23 toward the other yoke 23 coincides with the detection direction (maximum sensitivity direction) of the magnetic detection element 24. Figure 4 The lower part in FIG. 2 shows the case where the magnetic field generating unit 21 rotates. When the magnetic field generating unit 21 rotates, as shown in FIG. Figure 4 As shown in the lower section of the figure, the x direction and the y direction also rotate. The magnetic field formed by the magnetic field generating unit 21 is a closed magnetic field, so it is not easily affected by the external magnetic field. In addition, since the leakage of the magnetic field can be reduced, the size of the magnet 22 required to obtain a magnetic field of the same strength can be reduced.

[0029] Since the magnetic field generating unit 21 is integrally formed on the gear 14, when the gear 14 rotates, the magnetic field generating unit 21 also rotates, and the direction of the magnetic field lines also rotates. On the other hand, the magnetic detection element 24 is set on the housing cover 19 and does not rotate. Therefore, when the magnetic field generating unit 21 rotates with the rotation of the gear 14, the direction By of the magnetic field lines formed by the magnetic field generating unit 21 near its center is no longer consistent with the direction detected by the magnetic detection element 24, and the detection value of the magnetic detection element 24 changes. Therefore, the ECU can know the change in the direction of the magnetic field lines based on the change in the detection value of the magnetic detection element 24, and can know the rotation angle of the gear 14, and then know the rotation angle of the valve body 16.

[0030] like Figures 1 to 3 As shown in FIG. 1 , the fixing metal member 25 is arranged to overlap the magnetic field generating unit 21 described above in the z direction. The arrangement of the magnetic field generating unit 21 and the fixing metal member 25, as well as the shape and function of the fixing metal member 25 are described in detail below. Figure 5As shown, when viewed from the z direction, the outer edge of the fixing metal component 25 made of a magnetic body is roughly circular in size and roughly overlaps with the magnet 22 and the yoke 23 of the magnetic field generating unit 21, so it acts to shield the external magnetic field. Therefore, even if components such as a motor, wiring, or coils are arranged near the magnetic field generating unit 21 and the magnetic field from these components reaches the magnetic field generating unit 21, it is possible to suppress the magnetic lines of force brought by such external equipment from passing through the magnetic detection element 24 and affecting its detection value. As a result, Figure 6 As shown, even if a magnetic field (hereinafter, also referred to as an interfering magnetic field) from the outside invades, the influence on the detection value of the magnetic detection element 24 can be suppressed, so the rotation angle detection accuracy of the valve body 16 can be suppressed from being deteriorated. In addition, when viewed from the z direction, the fixing metal member 25 does not need to be of a size that its outer edge roughly overlaps with the magnet 22 and the yoke 23 of the magnetic field generating unit 21. The existence of the fixing metal member 25 of the magnetic body can shield the interfering magnetic field passing through the magnetic detection element 24.

[0031] The fixing metal member 25 is formed of a magnetic body, and thus forms a magnetic circuit with the magnet 22 and the yoke 23 and is magnetized, so that even if the spring 20 or the like is worn and wear powder is generated in the metal, the wear powder can be adsorbed by the fixing metal member 25. As a result, the wear powder can be prevented from being adsorbed to the magnet 22, and the influence on the magnetic detection element 24 can also be suppressed in this regard.

[0032] When viewed from the z direction, the fixing metal component 25 has an opening 25o at the rotation center O, and the shaft 15 is inserted into the opening 25o. The fixing metal component 25 and the shaft 15 are fixed by caulking. In the opening 25o, a fitting portion 27 is formed that is connected to the shaft 15 toward the rotation center O. The fitting portion 27 has a shape in which six concave and convex shapes appear repeatedly in the circumferential direction in the x-y plane, and one of the concave portions is a shape different from the others. Therefore, when its overall shape is viewed from the z direction, the fitting portion 27 is an asymmetric shape. The fixing metal component 25 is formed, for example, by press working. In the case where the fixing metal component 25 is formed by press working, there is a case where burrs 25b occur in the cut surface. In the present embodiment, since the fitting portion 27 has an asymmetric shape, when the fixing metal component 25 is formed by punching, the punching direction is known, and the formation direction of the burr 25b is known. If the formation direction of the burr 25b is known, the direction of the burr 25b can be aligned when the fixing metal component 25 is placed in the metal mold for forming the gear 14 and formed integrally with resin, and the influence of the burr 25b on the dimensional accuracy between the gear 14 and the fixing metal component 25 due to the interference between the burr 25b and the metal mold can be suppressed.

[0033] like Figure 6As shown, the fixing metal member is formed into the same shape as that of the present embodiment, and the influence of the disturbance magnetic field is reduced in the present embodiment formed of a magnetic body compared to the comparative example formed of a non-magnetic body.

[0034] Figures 7 to 11 Indicates other shapes of fixing metal parts. Figure 5 The fixing metal member 25 shown is substantially disc-shaped. In contrast, when viewed from the z direction, Figures 7 to 11 The fixing metal parts 25A to 25E shown in the figure have a shape with protrusions 26A to 26E on the outer periphery. In this case, as in the above-mentioned embodiment, the existence of the fixing metal parts 25A to 25E can obtain the effect of shielding the interfering magnetic field. These configuration examples are described in turn below. Figure 5 Compared with the fixing metal member 25 shown, Figure 7 The fixing metal component 25A shown is a shape in which a cutout is made at a position overlapping with the magnet 22. That is, the fixing metal component 25A is shaped to have a plurality of protrusions 26A, and the plurality of protrusions 26A protrude in a manner overlapping with the yoke 23 of the magnetic field generating portion 21. Since the gear 14 is insert-molded to be buried with the fixing metal component 25A, the presence of two protrusions 26A makes it possible to more reliably transmit the rotational force from the shaft 15 to the gear 14 via the fixing metal component 25A. The same is true when stopping the rotation. Due to the locking effect brought about by the protrusions 26A, even if a large rotational load acts on the gear 14, it is easy to suppress the occurrence of a situation where only the gear 14 rotates. Figures 7 to 11 This effect can be achieved in any of the embodiments including the protrusions 26A to 26E shown.

[0035] for Figure 7 As for the fixing metal component 25A shown in the figure, the two protrusions 26A have a shape that is symmetrical with respect to the yz plane passing through the rotation center O. Therefore, the protrusions 26A approach the two magnets 22 of the magnetic field generating unit 21 in the same shape, respectively, and have roughly the same influence on the magnetic flux density generated by each magnet 22, and do not distort the magnetic field generated by the magnetic field generating unit 21. As a result, it is possible to maintain the detection accuracy without affecting the detection of the magnetic flux density of the magnetic detection element 24, and it is possible to suppress the influence of the shape of the fixing metal component 25 when the magnetic detection element 24 detects the magnetic flux density. In addition, in Figure 7 In FIG. 1 , the fitting portion 27 also has an asymmetric shape. As described above, whether the shape of the fitting portion 27 is asymmetric or symmetric, there is no significant difference in the effect on the magnetic flux density detected by the magnetic detection element 24.

[0036] exist Figure 7In the embodiment, the two protrusions 26A of the fixing metal component 25A are shaped to overlap with the yoke 23 but not with the magnet 22. In this case, since the magnet 22, which is the source of the magnetic flux, does not overlap with the fixing metal component 25A, it is not easy to cause a situation in which the magnetic field formed by the magnetic field generating part 21 is affected by the fixing metal component 25A and the magnetic flux density detected by the magnetic detection element 24 is reduced. However, it is also possible to have a shape in which the two protrusions 26A are rotated 90 degrees relative to the installation position of the magnetic field generating part 21, and the protrusions 26A overlap with the magnet 22 but do not overlap with the center of the yoke 23. In this case, since the protrusions 26A are close to the two magnets arranged in the magnetic field generating part 21 in the same shape, the influence on the magnetic flux density generated by each magnet 22 is roughly the same, and the magnetic field detected by the magnetic detection element 24 is not distorted.

[0037] Figure 7 In the embodiment, when the fitting portion 27 is observed from the z direction, the fitting portion 27 has an asymmetric shape, so that the direction of the burr can be determined. Even if the fitting portion 27 does not have an asymmetric shape, the shape of the protrusion 26A and the shape of the fitting portion 27 can be used to distinguish the shape of the fixing metal component 25A when observed from the +z direction and the shape of the fixing metal component 25A when observed from the -z direction. For example, as long as the fitting portion 27 is made to have a shape having a plurality of concave and convex shapes and having a symmetry plane parallel to the z direction passing through the rotation center O of the gear 14, any symmetry plane parallel to the z direction passing through the rotation center O of the gear 14 with respect to the protrusion 26A is inconsistent with the symmetry plane with respect to the fitting portion 27. For example, in Figure 7 In the example shown, even if the fitting portion 27 is symmetrical, its symmetry plane does not coincide with any symmetry plane of 26A, so the front and back sides of the fixing metal member 25A can be easily distinguished. In this way, it is possible to determine on which side the burr is formed in the fixing metal member 25A based on the shape of the protrusion 26A and the shape of the fitting portion 27.

[0038] Figure 8 The illustrated fixing metal component 25B has three protrusions 26B1, 26B2, and 26B3. When the three protrusions are not distinguished, they are simply referred to as protrusions 26B. The three protrusions 26B are plane-symmetrical with respect to the yz plane. If the protrusions 26B are plane-symmetrical with respect to the yz plane, then the protrusions 26B1 and 26B3 are respectively arranged in the same shape close to the two magnets 22 arranged in the magnetic field generating part 21, so the influence of the protrusions 26B on the magnetic lines of force is also plane-symmetrical with respect to the yz plane. The influence of the protrusions 26B on each magnet 22 is roughly the same, and the distortion of the shape of the magnetic lines of force passing through the magnetic detection element 24 due to the presence of the protrusions 26B is suppressed. As a result, the influence of the shape of the fixing metal component 25 when the magnetic detection element 24 detects the magnetic flux density can be suppressed. In addition, Figure 8 , Fig. 9 In the embodiment, the three protrusions 26B1, 26B2, and 26B3 can be connected to form one protrusion 26B. In this case, since the protrusion 26B is symmetrical with the yz plane, the influence of the protrusion 26B on the magnetic force lines is also symmetrical with the yz plane. Therefore, the influence of the protrusion 26B on each magnet 22 is roughly the same, and the shape of the magnetic force lines passing through the magnetic detection element 24 caused by the presence of the protrusion 26B is suppressed. Therefore, the influence on the detection accuracy of the magnetic detection element 24 can be suppressed.

[0039] Fig. 9 The fixing metal part 25C illustrated in the figure has three protrusions 26C. The three protrusions 26C are plane-symmetrical with the yz plane as the symmetry plane, and the three protrusions 26C are evenly arranged on the circumference of the rotation center O of the gear 14 as the center. If the protrusions 26C are plane-symmetrical and evenly arranged with the yz plane as the symmetry plane, since the shapes of the protrusions 26C arranged close to the two magnets 22 of the magnetic field generating part 21 are respectively the same, they are plane-symmetrical with the yz plane as the symmetry plane. As a result, the influence of the protrusions 26C on each magnet 22 is roughly the same, and the distortion of the shape of the magnetic field lines passing through the magnetic detection element 24 caused by the presence of the protrusions 26C is suppressed. Therefore, the influence on the detection accuracy of the magnetic detection element 24 can be suppressed.

[0040] exist Figure 8 , Fig. 9 In the embodiment, when viewed from the z direction, the fitting portion 27 has an asymmetrical shape, but may also have a symmetrical shape. For example, the fitting portion 27 may be plane-symmetrical, with the plane passing through the rotation center O and outside the yz plane being the symmetric plane. In this case, it is possible to determine on which side the burr occurs the fixing metal member 25B or 25C based on the shape of the protrusion 26B or the protrusion 26C and the shape of the fitting portion 27. In addition, the same is true when the number of protrusions 26B or 26C is an odd number of 4 or more.

[0041] Fig.10 In the example shown, the fixing metal member 25D has four protrusions 26D. The four protrusions 26D are plane-symmetrical with the yz plane as the symmetry plane, and the four protrusions 26 are evenly arranged on the circumference of the circle centered on the rotation center O of the gear 14. Fig.10In the example shown, since the shapes of the protrusions 26D arranged close to the magnets 22 of the magnetic field generating part 21 are substantially the same, the influence of the protrusions 26D on the magnetic field lines is also plane-symmetrical with the yz plane as the symmetry plane. As a result, the influence of the protrusions 26D on the respective magnets 22 becomes substantially the same, so that the distortion of the detection magnetic flux of the magnetic detection element 24 is less likely to occur, and the influence of the shape of the fixing metal member 25 can be suppressed. In addition, as long as the four protrusions 26D are plane-symmetrical with the yz plane as the symmetry plane, the four protrusions 26D may not be uniformly arranged on the circumference with the rotation center O of the gear 14 as the center. In addition, it is also possible to make any symmetry plane parallel to the z direction about the protrusions 26D passing through the rotation center O of the gear 14 and any symmetry plane parallel to the z direction about the fitting part 27 passing through the rotation center O of the gear 14 not coincide with each other.

[0042] exist Fig.11 In the example shown, the fixing metal member 25E has five protrusions 26E, the five protrusions 26E are plane-symmetrical with the yz plane as the symmetry plane, and the five protrusions 26E are evenly arranged on the circumference of the circle centered on the rotation center O of the gear 14. Fig.11 In the example shown, since the shapes of the protrusions 26E arranged close to the magnets 22 of the magnetic field generating unit 21 are substantially the same, the influence of the protrusions 26E on the detection magnetic flux is also plane-symmetrical with the yz plane as the symmetry plane. As a result, the influence of the protrusions 26E on each magnet 22 is substantially the same, so that the distortion of the detection magnetic flux of the magnetic detection element 24 is less likely to occur, and the influence of the shape of the fixing metal member 25 can be suppressed.

[0043] The protrusion 26 may also be arranged to be plane-symmetrical without taking the yz plane as the symmetry plane. Fig.12 The example shown is to make Figure 8 The fixing metal member 25B used in the embodiment is mounted on the shaft 15 after being rotated 135° clockwise around the rotation center O of the shaft 15 . Fig.12 The fixing metal member 25B shown is Figure 8 The example shown also has three protrusions 26B, but Figure 8 Unlike the example shown, the protrusion 26B is not arranged at a plane-symmetrical position with the yz plane as the symmetry plane. However, in this case, the presence of the fixing metal member 25B can also achieve the effect of shielding the interfering magnetic field. In addition, the presence of three protrusions 26B can also achieve the effect of more reliably transmitting the rotational force from the shaft 15 to the gear 14 via the fixing metal member 25B.

[0044] like Fig.13 As shown, it means using Fig.12The output error curve of the case where the fixing metal component 25B is . As shown in the figure, in this case, gain error and offset error occur in the output error. On the other hand, if the fixing metal component 25B is Figure 8 By comparing the two, it can be seen that no matter which of the protrusions 26A to 26E is used, as long as the protrusions are arranged in the same shape and close to the two magnets 22 that generate the magnetic field, the gain error and offset error when the magnetic detection element 24 performs detection can be suppressed, which is more preferable.

[0045] use Fig.14 The fixing by caulking is described below. The end 15e of the shaft 15 is formed to be thinner than the shaft 15. First, the fixing metal component 25 is installed by inserting the end 15e into the opening 25o of the fixing metal component 25. Next, the end 15e is flattened and expanded little by little using a caulking forming jig 50. Then, the fixing metal component 25 is fixed by clamping the main body of the shaft 15 and the flattened end 15e. In addition, the shape of the end 15e of the shaft 15 can also be made into a hollow tube shape. In addition, the installation of the shaft 15 and the fixing metal component 25 can also be done by other methods such as high-frequency welding, laser welding, etc. instead of caulking.

[0046] · Second embodiment:

[0047] like Fig.15 As shown in the second embodiment, the magnetic field generating unit does not include a yoke but includes a magnet 22b. The magnet 22b is disposed between the fixing metal component 25 and the magnetic detection element 24, and the direction of the magnetic pole is perpendicular to the direction along the axis 15. The magnet 22b is cast with a magnet casting component 28 and is integrally molded on the gear 14 with the fixing metal component 25 by resin. Fig.15 As shown, the magnetic flux density of the magnet 22b comes out from the N pole, passes through the magnetic detection element 24, and enters the S pole. The magnetic detection element 24 detects the passing magnetic flux density.

[0048] As the magnet 22b, Fig.16 As shown, a circular magnet magnetized in the diameter direction, a quadrilateral magnet, a magnet with a pole side made into an arc, or other magnets may be used. In addition, an elliptical magnet magnetized in the long diameter or short diameter direction may also be used. The number of magnets does not need to be limited to one, and two or more magnets may be used.

[0049] In the second embodiment, since the fixing metal component 25 suppresses the application of the interfering magnetic field to the magnetic field lines generated by the magnet 22, it is possible to suppress the deterioration of the detection accuracy of the detection angle calculated based on the magnetic flux density, as in the first embodiment. In addition, the shapes of the protrusion 26 and the fitting portion 27 of the fixing metal component 25 are the same as those described in the first embodiment, and are plane-symmetrical with respect to the symmetry plane of the magnetic field lines generated by the magnet. Therefore, the same effect as described in the first embodiment is achieved.

[0050] In the above description, the electronically controlled throttle valve 10 for controlling the intake air amount to the engine of the vehicle is used as an example, but it can also be an EGR valve for controlling the exhaust gas recirculation amount of the EGR device, various valves for superchargers, or valves for controlling water flow, etc., for detecting the opening of a rotating valve body. It can also be used in mobile bodies other than vehicles or equipment installed in factories, etc., for detecting the rotation angle of various rotating bodies. The rotation angle range to be detected can also be less than 360 degrees, and the rotation angle of more than 360 degrees can be detected by gear reduction.

[0051] The present invention is not limited to the above-mentioned embodiments, and can be implemented in various structures within the scope of the main purpose. For example, in order to solve part or all of the above-mentioned problems, or to achieve part or all of the above-mentioned effects, the technical features of the embodiments corresponding to the technical features in each form recorded in the invention content column can be appropriately replaced or combined. In addition, as long as the technical features are not described as necessary in this specification, they can be appropriately deleted.

Claims

1. A rotation angle detection device for detecting the rotation angle of a valve body (16). The above-mentioned rotation angle detection device comprises: A shaft (15) connected to the valve body; a gear (14) connected to the shaft, and causing the valve body to rotate by the rotation of the shaft; A magnetic field generating unit (21), arranged on the gear side, generates a magnetic field; A magnetic fixing metal component (25) is provided at a position covering at least a portion of the magnetic field generating portion and is used to fix the gear to the shaft; and A magnetic detection element (24) is arranged on an extension line of the shaft and detects the magnetic flux density of the magnetic field rotating with the rotation of the gear. The fixing metal part has an odd number of protrusions (26) of three or more protruding in the radial direction of a circle centered on the axis. The protrusions are arranged in a manner that the shapes of the protrusions arranged close to the pair of magnets of the magnetic field generating part are the same as each other, and are plane-symmetrical with respect to the symmetry plane of the magnetic field lines formed by the magnetic field generating part. The protrusions are unevenly arranged on a circumference centered on the rotation center of the gear.

2. The rotation angle detection device according to claim 1, The magnetic field generating unit has: a pair of magnets (22); and A pair of yokes (23) for connecting the N poles and the S poles of the pair of magnets, respectively, and forming a shape along a plane perpendicular to the direction along the axis together with the pair of magnets; The magnetic field generating unit generates a closed magnetic field.

3. The rotation angle detection device according to claim 1, The magnetic field generating unit includes a magnet disposed between the fixing metal member and the magnetic detection element, wherein a magnetic pole of the magnet is oriented in a direction perpendicular to a direction along the axis.

4. The rotation angle detection device according to any one of claims 1 to 3, The portion where the gear is fixed to the shaft is made of resin; The fixing metal member is molded integrally with the resin of the gear.

5. The rotation angle detection device according to any one of claims 1 to 3, The fixing metal component has a fitting portion (27) that penetrates and fixes the protrusion provided at the front end of the shaft. The fitting portion has an asymmetrical shape when viewed from a direction along the axis.

6. The rotation angle detection device according to any one of claims 1 to 3, The above-mentioned fixing metal member is a cold-rolled steel plate.

7. The rotation angle detection device according to any one of claims 1 to 3, The fixing of the fixing metal member and the shaft is performed by caulking.

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