Rotation angle sensor and parking lock sensor using it

Abstract

This invention provides a rotation angle sensor with sufficient magnetic field detection performance using a small magnet. The rotation angle sensor (1A) has a central magnetic body (3) that rotates around a rotation center (C) and is magnetized in a predetermined direction, a pair of side magnetic bodies (4A, 4B), and a magnetic field detection element (5) that detects the magnetic field formed by the central magnetic body and the pair of side magnetic bodies. Regarding each of the pair of side magnetic bodies, when the vector representing the magnetization direction of the side magnetic body and pointing away from the rotation center from the center of the side magnetic body is taken as the magnetization direction vector (V2) of the side magnetic body; when the vector on the extension of the line connecting the rotation center and the center of the side magnetic body and pointing away from the rotation center from the center of the side magnetic body is taken as the reference vector (V1), the magnetization direction vector (V2) rotates relative to the reference vector (V1) toward the central magnetic body (3).

Description

Technical Field

[0001] This application is based on Japanese Patent Application No. 2021-188772, filed on November 19, 2021, and claims priority based on that application. That application is incorporated herein by reference in its entirety.

[0002] This invention relates to a rotation angle sensor and a parking lock sensor using the same. Background Technology

[0003] Rotation angle sensors for detecting the rotation angle of a rotating body are known. Japanese Patent Application Publication No. 2017-90105 discloses a rotation angle sensor comprising three magnets disposed around the rotation center of a rotating support, and a magnetic field detection element for detecting the magnetic field formed by the three magnets. The shapes of the three magnets are linearly symmetrical about a line passing through the rotation center of the support and the center of each magnet. Furthermore, the magnetization directions of the three magnets are parallel to lines passing through the rotation center of the support and the center of each magnet. Summary of the Invention

[0004] In the rotation angle sensor disclosed in Japanese Patent Application Publication No. 2017-90105, the magnetic flux lines (magnetic lines of force) emanating from a magnet follow a path that, once leaving an adjacent magnet, heads towards the next adjacent magnet. Therefore, the magnetic flux lines tend to diffuse, potentially making it difficult to ensure sufficient magnetic field strength at the location of the magnetic field detection element. Consequently, the magnets need to be larger, which may limit cost reduction or miniaturization of the rotation angle sensor.

[0005] The purpose of this invention is to provide a rotation angle sensor that has sufficient magnetic field detection performance with a small magnet.

[0006] The rotation angle sensor of the present invention includes: a central magnetic body and a pair of lateral magnetic bodies that are magnetized in a predetermined direction and rotate around a rotation center; and a magnetic field detection element that detects the magnetic field formed by the central magnetic body and the pair of lateral magnetic bodies. The central magnetic body is disposed between the pair of lateral magnetic bodies in the rotation direction of the central magnetic body and the pair of lateral magnetic bodies, and the radially outer magnetic poles of the central magnetic body and the pair of lateral magnetic bodies are opposite to each other. Regarding each of the pair of lateral magnetic bodies, when a vector representing the magnetization direction of a lateral magnetic body, originating from the center of the lateral magnetic body and moving away from the rotation center, is taken as the magnetization direction vector of the lateral magnetic body; and when a vector located on the extension of the line connecting the rotation center and the center of the lateral magnetic body, originating from the center of the lateral magnetic body and moving away from the rotation center, is taken as the reference vector of the lateral magnetic body, the magnetization direction vector rotates relative to the reference vector towards the central magnetic body.

[0007] According to the present invention, a rotation angle sensor with sufficient magnetic field detection performance using a small magnet can be provided.

[0008] The above and other objects, features and advantages of this application will become apparent from the detailed description which follows, with reference to the accompanying drawings illustrating this application. Attached Figure Description

[0009] Figure 1A , 1B This is a conceptual diagram of the rotation angle sensor (φ≠θ) involved in the first embodiment.

[0010] Figure 2A , 2B yes Figure 1A , 1B A magnified view of a portion of the image.

[0011] Figure 3 This is a conceptual diagram of a comparative example of a rotation angle sensor.

[0012] Figure 4 This is a conceptual diagram of the rotation angle sensor (φ=θ) involved in the first embodiment.

[0013] Figures 5A-5C This is a conceptual diagram of the rotation angle sensor involved in the second embodiment.

[0014] Figure 6A , 6B This is a conceptual diagram of the rotation angle sensor involved in the third embodiment.

[0015] Figures 7A-7C This is a conceptual diagram of the rotation angle sensor involved in the fourth embodiment.

[0016] Figures 8A-8C This is a conceptual diagram of the rotation angle sensor involved in the fifth embodiment.

[0017] Figure 9A , 9B This is a conceptual diagram of the rotation angle sensor involved in the sixth embodiment.

[0018] Figure 10 This is a conceptual diagram of a parking lock sensor with a rotation angle sensor.

[0019] Figure 11 This is a diagram showing a comparison of the rotation angle sensors of the embodiment and the comparative example.

[0020] Figure 12 This is a calculation example representing the preferred range of angle θ. Detailed Implementation

[0021] Several embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, "circumferential" refers to the direction of rotation with respect to the rotation center C of the support body 2, that is, the direction along the tangent of the circle centered at the rotation center C of the support body 2. "Radial" refers to the direction with respect to the rotation center C of the support body 2, that is, the direction of the straight line passing through the rotation center C of the support body 2. "Angular position" refers to the angle with respect to the rotation center C of the support body 2, that is, the angle in polar coordinates with the rotation center C of the support body 2 as the origin. Furthermore, in the figures, the dashed lines connecting the central magnetic body 3 and the side magnetic bodies 4A and 4B conceptually represent magnetic flux lines (magnetic lines of force).

[0022] (First Implementation)

[0023] Figures 1A-2B This diagram illustrates a schematic structure of the rotation angle sensor 1A according to the first embodiment of the present invention. The rotation angle sensor 1A includes a support body 2, a central magnetic body 3 supported by the support body 2, a pair of lateral magnetic bodies 4A and 4B, and a magnetic field detection element 5. The support body 2 is formed of a non-magnetic metal or resin, and a hole 21 for fixing the support body 2 to a rotating shaft (not shown) is provided at the center of the support body 2. The support body 2 shares a rotation center C with the rotating shaft (not shown) and rotates together with the rotating shaft around the rotation center C. Therefore, the rotation angle of the rotating shaft can be detected by detecting the rotation angle of the support body 2. Furthermore, the support body 2 can be formed using a magnetic material such as a magnetic metal, giving the support body 2 a magnetic focusing function as a yoke, thereby enhancing the magnetic flux density at the location where the magnetic field detection element 5 is installed.

[0024] The support 2 supports a central magnetic body 3 and a pair of lateral magnetic bodies 4A and 4B (hereinafter sometimes referred to as the first lateral magnetic body 4A and the second lateral magnetic body 4B). The support 2 is a circular plate, and the central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are supported by any one plane of the support 2. The central magnetic body 3 is circumferentially positioned between the pair of lateral magnetic bodies 4A and 4B. The difference between the angular position of the center of the central magnetic body 3 and the angular position of the center of the first lateral magnetic body 4A, and the difference between the angular position of the center of the central magnetic body 3 and the center of the second lateral magnetic body 4B are equal. That is, the central magnetic body 3 is located between the first lateral magnetic body 4A and the second lateral magnetic body 4B. However, the difference between the angular position of the center of the central magnetic body 3 and the angular position of the center of the first lateral magnetic body 4A, and the difference between the angular position of the center of the central magnetic body 3 and the center of the second lateral magnetic body 4B, is less than 90°. The first lateral magnetic body 4A and the second lateral magnetic body 4B have the same shape and size. Furthermore, the radial positions of the centers of the first lateral magnetic body 4A and the second lateral magnetic body 4B, i.e., the distances from the rotation center C, are equal. In contrast, the radial (magnetization direction) length of the central magnetic body 3 is greater than the radial length of the pair of lateral magnetic bodies 4A and 4B, and the radial position of the center of the central magnetic body 3 is on the inside compared to the radial positions of the centers of the pair of lateral magnetic bodies 4A and 4B.

[0025] The central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are all magnets, formed of magnetic materials such as neodymium. The central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are magnetized in a predetermined direction. The radially outer magnetic poles of the central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are opposite to each other. In this embodiment, the radially outer magnetic pole of the central magnetic body 3 is the S pole, and the radially outer magnetic poles of the pair of lateral magnetic bodies 4A and 4B are the N poles. However, it is also possible that the radially outer magnetic pole of the central magnetic body 3 is the N pole, and the radially outer magnetic poles of the pair of lateral magnetic bodies 4A and 4B are the S poles. The central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are cuboids. Therefore, the magnetization direction of the central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B is parallel to any side of the cuboid.

[0026] The magnetic field detection element 5 is mounted on a predetermined fixed part (not shown) such that the support body 2 can rotate relative to the magnetic field detection element 5. The magnetic field detection element 5 detects the magnetic field formed by the central magnetic body 3 and a pair of lateral magnetic bodies 4A and 4B. The magnetic field detection element 5 is preferably positioned at the center of the angle detection range α of the rotation angle sensor 1A. The angle detection range α is clamped by the straight line connecting the center of the first lateral magnetic body 4A and the rotation center C, and the straight line connecting the center of the second lateral magnetic body 4B and the rotation center C, and is an angle range of 180° or less where the magnetic field detection element 5 is mounted. The magnetic field detection element 5 has elements for detecting the radial magnetic field strength and elements for detecting the circumferential magnetic field strength. The type of element is not limited; in addition to Hall elements, magnetoresistive elements such as AMR elements and TMR elements can be used. The arithmetic unit (not shown) of the rotation angle sensor 1A calculates the angle of the composite magnetic field from the magnetic field strength detected by these elements. Because the distribution of the magnetic field formed by the central magnetic body 3 and a pair of lateral magnetic bodies 4A and 4B is predetermined, the rotation angle of the support body 2 can be detected by the angle of the combined magnetic field.

[0027] As explained above, the first lateral magnetic body 4A and the second lateral magnetic body 4B are mirror-symmetric about the straight line connecting the center of the central magnetic body 3 and the rotation center C (hereinafter referred to as the first straight line L1). Therefore, the magnetic field distribution is mirror-symmetric about the first straight line L1, which improves measurement accuracy. Furthermore, since the explanation of the first lateral magnetic body 4A is applicable to each of the pair of lateral magnetic bodies 4A and 4B, the first lateral magnetic body 4A will be described in the following explanation. However, it should be noted that structures in which the first lateral magnetic body 4A and the second lateral magnetic body 4B are not mirror-symmetric about the first straight line L1 are also included in this invention.

[0028] Here, the terminology used in the following description will be explained.

[0029] - First straight line L1: The straight line connecting the center P of the central magnetic body 3 and the rotation center C.

[0030] - Second straight line L2: The straight line connecting the center Q of the lateral magnetic bodies 4A and 4B with the rotation center C.

[0031] - Reference vector V1: A vector located on the extension of the second straight line L2, originating from the center Q of the lateral magnetic bodies 4A and 4B and moving away from the rotation center C.

[0032] - Magnetization direction vector V2: A vector representing the magnetization direction of lateral magnetic bodies 4A and 4B, originating from the center Q of the lateral magnetic bodies 4A and 4B and pointing away from the rotation center C.

[0033] -θ: The angle formed by the magnetization direction vector V2 and the reference vector V1 (unit: °)

[0034] -φ: The angle formed by the first line L1 and the reference vector V1 (or, the angle formed by the first line L1 and the second line L2 (unit: °)).

[0035] Because the magnetization direction of the central magnetic body 3 is parallel to the first straight line L1, the first straight line L1 is parallel to the magnetization direction of the central magnetic body 3.

[0036] Figure 2A , 2B They are Figure 1A , 1B A partially enlarged view shows the central magnetic body 3, the first lateral magnetic body 4A, the first straight line L1, the second straight line L2, the reference vector V1, the magnetization direction vector V2, and the angles θ and φ. For ease of explanation, in... Figure 2A , 2B The diagram also shows a straight line L3 that is orthogonal to the reference vector V1. Figure 3 The diagram shows a schematic structure of the rotation angle sensor 101 in the comparative example, where θ = 0°. In contrast, in this embodiment, the magnetization direction vector V2 faces a direction different from the reference vector V1 (θ ≠ 0°). More specifically, the magnetization direction vector V2 rotates relative to the reference vector V1 towards the central magnetic body 3 (or toward the central magnetic body 3, or in a direction closer to the central magnetic body 3). Figure 1A In the context of magnetization, the angular difference between the magnetization direction vector V2 and the reference vector V1 is small, θ < φ. Figure 1B In this context, the angle difference between the magnetization direction vector V2 and the reference vector V1 is large, θ > φ. However, as described later, if the angle θ is too large, the rotation angle detection performance of the sensor will decrease; therefore, it is preferable that the maximum value of θ is less than 90°. That is, the angle θ can be within the range θ between the reference vector V1 and the straight line L3 orthogonal to it. A (However, exceptions apply to θ=0° and θ=90°.) Due to limitations such as less than 90°, the angle range θ... A The upper limit can vary depending on the structure of the rotation angle sensor, so it can also be other values. Angle range θ A The upper limit can be appropriately set as 40°, 50°, 60°, 70°, 80°, etc.

[0037] Reference Figure 2A , 2BBecause the magnetization direction vector V2 rotates towards the central magnetic body 3, the magnetic flux lines are short, making it easier to enhance the magnetic field strength at the magnetic field detection position. In the comparative example, since the magnetization direction vector V2 overlaps with the reference vector V1, the magnetic flux lines are long. Therefore, to ensure the magnetic field strength at the magnetic field detection position, it is necessary to increase the size of the magnet, etc. In contrast, in this embodiment, compared with existing rotation angle sensors, it is easier to reduce the size of the magnet, thereby reducing the cost or miniaturizing the rotation angle sensor 1A.

[0038] As mentioned above, the angle θ can be derived from the angle range θ A Choice. When the angle θ is small, the diffusion range of the magnetic flux lines expands, thus increasing the angle detection range α. Therefore, for applications requiring a large angle detection range α, it is preferable to decrease the angle θ. On the other hand, when the angle θ is large, the diffusion range of the magnetic flux lines is limited, thus decreasing the angle detection range α while improving detection accuracy. Therefore, although a small angle detection range α is also acceptable, for applications requiring high detection accuracy, it is preferable to increase the angle θ within a specified range.

[0039] exist Figure 4 In the example shown, the magnetization direction vector V2 is parallel to the first straight line L1 (φ=θ). The central magnetic body 3 and the pair of side magnetic bodies 4A and 4B are magnetized in the same direction. In other words, in the central magnetic body 3 and the pair of side magnetic bodies 4A and 4B, one of the three axes of the cuboid is parallel to each other. This configuration is particularly advantageous from a manufacturing process perspective. To configure the central magnetic body 3 and the pair of side magnetic bodies 4A and 4B with different orientations, fixtures for positioning (control of angle θ) and a measuring device for angle θ are required. In contrast, when the central magnetic body 3 and the pair of side magnetic bodies 4A and 4B are configured with the same orientation, the manufacturing equipment or process is simplified, and positioning accuracy is easily ensured.

[0040] The angle detection range α can also be adjusted by adjusting the angular positions of the pair of lateral magnetic bodies 4A and 4B. Although the illustration is omitted, the angle detection range α can be increased by increasing the angle φ to move the lateral magnetic bodies 4A and 4B away from the central magnetic body 3. On the other hand, the angle detection range α can be decreased by decreasing the angle φ to move the lateral magnetic bodies 4A and 4B closer to the central magnetic body 3. However, the angle φ is preferably in the range of 0° < φ ≤ 90°.

[0041] Hereinafter, another embodiment of the present invention will be described. The structure of the support body 2, the central magnetic body 3, and the structure of the pair of side magnetic bodies 4A and 4B in the other embodiment are different from those in the first embodiment. The structures and effects described herein are the same as those in the first embodiment.

[0042] (Second Implementation)

[0043] Figures 5A-5C This is a conceptual diagram of the rotation angle sensor 1B according to the second embodiment. Figure 5A This is a front view of the rotation angle sensor 1B. Figure 5B This shows a side view of the rotation angle sensor 1B. Figure 5C This is a perspective view of the rotation angle sensor 1B. The support body 2 is a shape obtained by cutting the circular plate of the first embodiment with a straight line that does not pass through the rotation center C, or a circular shape with a D-shaped cut. The side of the support body 2 has an arc-shaped curved surface 22 and a flat surface 23 connecting the two ends of the curved surface 22. The central magnetic body 3 and a pair of lateral magnetic bodies 4A, 4B are supported by the flat surface 23. The central magnetic body 3 and the pair of lateral magnetic bodies 4A, 4B are fixed to the flat surface 23, for example, by an adhesive. The central magnetic body 3 has a longer length in the magnetization direction compared to the pair of lateral magnetic bodies 4A, 4B. The rotation angle sensor 1B of this embodiment has a simple structure because it does not require a structure to support the central magnetic body 3 and the pair of lateral magnetic bodies 4A, 4B. Furthermore, in the first embodiment, the central magnetic body 3 and a pair of lateral magnetic bodies 4A and 4B are mounted on a circular plate-shaped support 2. Therefore, the center of gravity of the structure consisting of the support 2, the central magnetic body 3, and the pair of lateral magnetic bodies 4A and 4B deviates from the rotation center C. Thus, depending on the application, there is a possibility that the effect of this eccentricity may affect the rotation axis on which the support 2 is mounted. Eccentricity can also be achieved by changing some or all of the materials of the central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B (e.g., replacing materials with a specific gravity of approximately 7.4 g / cm³). 3 Neodymium, with a specific gravity of approximately 4.8 g / cm³. 3 In this embodiment, the eccentricity can be further suppressed by adjusting the material of the support 2, the position of the flat part 23 from the rotation center C, etc.

[0044] (Third implementation method)

[0045] Figure 6A This is a conceptual diagram of the rotation angle sensor 1C according to the third embodiment, and... Figure 1A , 1BThe diagram shows a front view of the rotation angle sensor 1C. The structure of the support 2 is the same as in the second embodiment. That is, the support 2 is a flat plate, and the side of the flat plate has an arc-shaped curved surface 22 and a flat surface 23 connecting the two ends of the curved surface 22. For details of the structure of the support 2, please refer to the second embodiment. The rotation angle sensor 1C further includes a soft magnetic body 6 supported by the flat surface 23. A central magnetic body 3 and a pair of lateral magnetic bodies 4A and 4B are supported by the soft magnetic body 6. The soft magnetic body 6 is a flat plate and can be made of materials such as NiFe. The central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are fixed at a predetermined position on the soft magnetic body 6. Compared with the pair of lateral magnetic bodies 4A and 4B, the central magnetic body 3 has a longer length in the magnetization direction. The central magnet 3 and the pair of lateral magnets 4A and 4B can also be fixed magnetically. In this case, the central magnet 3 and the pair of lateral magnets 4A and 4B can be sealed with a non-magnetic resin, or they can be fixed with an adhesive. In this embodiment, the central magnet 3, the pair of lateral magnets 4A and 4B, and the soft magnetic body 6 can be prepared as an assembly in advance. Therefore, even if the central magnet 3 and the pair of lateral magnets 4A and 4B need to be installed on the support 2 at the manufacturing plant where the rotation angle sensor 1C is installed, the installation work can be easily performed. Since the soft magnetic body 6 acts as a magnetic yoke, a circulating magnetic flux is formed through the central magnet 3, the pair of lateral magnets 4A and 4B, and the soft magnetic body 6, which can enhance the magnetic flux intensity.

[0046] Figure 6B This is a conceptual diagram of the rotation angle sensor 1C involved in a variation of the third embodiment, and... Figure 1A , 1B Similarly, this is a front view of the rotation angle sensor 1C. In this modified example, the soft magnetic body 6 has a flat plate portion 61 and a protrusion 62 that protrudes radially outward at approximately a right angle from the flat plate portion 61. That is, the soft magnetic body 6 as a whole has a T-shaped shape. The central magnetic body 3 is supported by the protrusion 62, and a pair of lateral magnetic bodies 4A and 4B are supported by the flat plate portion 61. In this modified example, compared with the third embodiment, the length of the magnetization direction of the central magnetic body 3 can be shortened, thus reducing the volume of expensive magnets and achieving cost reduction. In particular, in this modified example, the central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B have the same shape and size. Because the same magnet can be used for the central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B, the manufacturing process is simplified.

[0047] (Fourth Implementation)

[0048] Figures 7A-7C This is a conceptual diagram of the rotation angle sensor 1D according to the fourth embodiment. Figure 7AThis is a front view of the rotation angle sensor 1D. Figure 7B This shows a side view of the rotation angle sensor 1D. Figure 7C This is a perspective view of the rotation angle sensor 1D. The structure of the support body 2 is the same as in the second embodiment. That is, the support body 2 is a flat plate, and the side of the flat plate has an arc-shaped curved surface 22 and a flat surface 23 connecting the two ends of the curved surface 22. For details of the structure of the support body 2, please refer to the second embodiment. The rotation angle sensor 1D of this embodiment further includes a support member 7 supported by the support body 2. The support member 7 has a first flat plate portion 71 supported by the flat surface 23, a second flat plate portion 72 protruding radially outward from the first flat plate portion 71, and a third flat plate portion 73 protruding radially inward from the first flat plate portion 71. The central magnetic body 3 and a pair of lateral magnetic bodies 4A, 4B are supported by the second flat plate portion 72, and the third flat plate portion 73 is supported by any one of the planes of the support body 2. The central magnetic body 3 and the pair of lateral magnetic bodies 4A, 4B can also be supported by the first flat plate portion 71. The first flat plate portion 71 and the second flat plate portion 72, and the second flat plate portion 72 and the third flat plate portion 73 are orthogonal to each other. A hole 74 is provided in the third plate portion 73, and a threaded hole 24 is cut into the support body 2 at a position opposite to the hole 74. The support member 7 is fixed to the support body 2 by means of a screw 8 that engages with the threaded hole 24 through the hole 74. The first plate portion 71 is aligned with the back of the support body 2 and can also extend from the support body 2. The support member 7 can be made of resin and can be formed as thin as possible while ensuring strength, thus achieving cost reduction.

[0049] (Fifth Implementation)

[0050] Figures 8A-8C This is a conceptual diagram of the rotation angle sensor 1E according to the fifth embodiment. Figure 8A This is a front view of the rotation angle sensor 1E. Figure 8B This shows a side view of the rotation angle sensor 1E. Figure 8CThis is a perspective view of the rotation angle sensor 1E. The support body 2 has a flat plate portion 25 and three support plates 26-28 protruding from the flat plate portion 25. The structure of the flat plate portion 25 is the same as in the second embodiment. That is, the flat plate portion 25 is a flat plate, and the side of the flat plate has an arc-shaped curved surface 22 and a flat surface portion 23 connecting the two ends of the curved surface 22. The three support plates 26-28 are L-shaped, strip-shaped members that protrude from the flat plate portion 25. The central magnetic body 3 and a pair of lateral magnetic bodies 4A and 4B are supported by the three support plates 26-28 respectively. The central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are supported near the front end of the support plates 26-28 by surfaces 29 of the support plates facing the opposite side to the rotation center C. The support plates 26-28 have the same thickness as the flat plate portion 25 and are integrally formed with the flat plate portion 25. Since the support plates 26-28 can be formed as thin as possible while ensuring strength, the flat plate portion 25 can also be formed relatively thin. The support plates 26-28 can also be straight components without bending. In this case, the central magnetic body 3 and the pair of lateral magnetic bodies 4A, 4B are not on the magnetic pole faces, but are mounted on the sides of the support plates 26-28 orthogonal to the two magnetic pole faces. Since the support plates 26-28 can be manufactured by bending, it is preferable that the support body 2 containing the support plates 26-28 is formed of metal, but it can also be formed of resin. The support body 2 containing the support plates 26-28 can be formed of non-magnetic metal or magnetic materials such as magnetic metal, giving the support body 2 a magnetic focusing function as a yoke, thereby increasing the magnetic flux density at the location where the magnetic field detection element 5 is installed.

[0051] (Sixth Implementation Method)

[0052] Figure 9A This is a conceptual diagram of the rotation angle sensor 1F according to the sixth embodiment, and... Figure 1A , 1B Similarly, this is a front view of the rotation angle sensor 1F. The central magnetic body 3 is a magnet, as in the embodiment described above, while the pair of lateral magnetic bodies 4A and 4B are soft magnetic bodies. The soft magnetic bodies are magnetized by the central magnetic body 3 and function as magnets. The soft magnetic bodies are formed of materials such as NiFe. Since magnets are not required as a pair of lateral magnetic bodies 4A and 4B in this embodiment, the size of expensive magnets can be reduced, thus lowering costs. In this embodiment, the support 2 is a circular plate, but the structure of the support 2 is not limited and can be combined with the second to fifth embodiments.

[0053] Figure 9B This is a conceptual diagram of the rotation angle sensor 1F involved in a variation of the sixth embodiment, and... Figure 1A , 1BSimilarly, this is a front view of the rotation angle sensor 1F. In this modified example, the pair of lateral magnetic bodies 4A and 4B are magnets, and the central magnetic body 3 is a soft magnetic body magnetized by the pair of lateral magnetic bodies 4A and 4B. This modified example can also achieve the same effect as the sixth embodiment.

[0054] (Seventh Implementation)

[0055] Figure 10 This is a conceptual diagram of a parking lock sensor 9 having the aforementioned rotation angle sensor 1A. The parking lock sensor 9 is used in the parking lock device 12 of an automatic transmission 11 of an automobile. When the gear lever is operated to the parking position, the parking lock device 12 locks the output shaft 13 of the automatic transmission 11 to prevent wheel rotation. A first gear 14 is integrally formed on the output shaft 13. A parking lever 15, capable of rocking about a fulcrum 15A, is provided near the first gear 14. A second gear 16 is formed on the parking lever 15, opposite to and capable of engaging with the first gear 14. The parking lever 15 can be moved by a drive device 17 to a position where the second gear 16 engages with the first gear 14 and a position where the second gear 16 disengages from the first gear 14. When the gear lever is operated to the parking position, a rotating shaft 19 is rotated by the engine 18. The drive device 17 is connected to the rotating shaft 19, converting the rotation of the rotating shaft 19 into the rocking motion of the parking lever 15. In such a parking lock device 12, it is necessary to detect the rotation angle of the rotating shaft 19 in order to control the parking lock device 12. For this purpose, a parking lock sensor 9 is provided on the rotating shaft 19. In this embodiment, the rotating shaft is the rotating shaft 19 between the engine 18 and the drive unit 17.

[0056] (Example)

[0057] First, for both the embodiment and the comparative example, the relationship between the rotation angle of the support 2 and the magnetic flux density at the location of the magnetic field detection element 5, and the relationship between the rotation angle of the support 2 and the angular error of the rotation angle sensor, were obtained. The results are as follows: Figure 11 As shown. Angular error is the difference between the detected rotation angle and the actual rotation angle at each angular position. The rotation angle sensor in the comparative example is... Figure 3 The comparative example shown is largely the same, with a central magnetic body 3 and a pair of lateral magnetic bodies 4A and 4B arranged along the outer periphery of the circular support 2. More specifically, the central magnetic body 3 and the pair of lateral magnetic bodies 4A and 4B are mounted on a yoke of a soft magnetic body, which is fixed to the support 2 by bolts 8. Embodiment and Figure 6A The fourth embodiment shown is largely the same. Compared to the comparative example, this embodiment has a higher minimum magnetic flux density and a smaller angular error. Furthermore, the total volume of the magnet is reduced by approximately 40% compared to the comparative example.

[0058] Next, the adjustable range of angle θ is determined. Specifically, by varying the angle (2φ) between the straight line connecting the centers of a pair of lateral magnetic bodies 4A and 4B and the rotation center C, the adjustable range is determined, thus detecting the upper limit of the rotation angle θ. The results are as follows: Figure 12 As shown. When the angle θ exceeds the upper limit, the magnetic flux vector angle will rotate more than 360°, making the rotation angle undetectable. When the angle φ is small, the adjustable range of angle θ is small, for example, about 30° when φ = 20°. As the angle φ increases, the adjustable range of angle θ also increases. However, when the angle φ increases further, the adjustable range of angle θ decreases. Thus, the maximum upper limit of the detectable rotation angle θ is 82.5° (2φ = 70°). However, since the upper limit of θ also depends on the dimensions of the central magnetic body 3 and the side magnetic bodies 4A and 4B, the above value is only an example. For a large adjustable range, it is preferable that 2φ is around 60–80° (φ is 30–40°).

[0059] While several preferred embodiments of the invention have been shown and described in detail, it should be understood that various changes and modifications can be made without departing from the spirit or scope of the appended claims.

[0060] Explanation of reference numerals in the attached figures

[0061] 1A~1F……Rotation Angle Sensor

[0062] 2... Support body

[0063] 3... Central magnetic body

[0064] 4A, 4B... Lateral magnetic bodies

[0065] 5...Magnetic field detection element

[0066] 6... Soft magnetic materials

[0067] 7……Supporting components

[0068] 9... Parking lock sensor

[0069] 26~28……Support plate

[0070] C……Center of Rotation

Claims

1. A rotation angle sensor, wherein: have: A central magnetic body and a pair of lateral magnetic bodies rotate around a center of rotation and are magnetized in a prescribed direction; and A magnetic field detection element detects the magnetic field formed by the central magnetic body and the pair of lateral magnetic bodies. The central magnetic body is positioned between the pair of side magnetic bodies in the direction of rotation of the central magnetic body and the pair of side magnetic bodies, and the radially outer magnetic poles of the central magnetic body and the pair of side magnetic bodies are opposite to each other. Regarding each of the pair of lateral magnetic bodies Let represent the magnetization direction of the lateral magnetic body, and let the vector originating from the center of the lateral magnetic body and pointing away from the center of rotation be the magnetization direction vector of the lateral magnetic body; and Let the vector located on the extension of the line connecting the center of rotation and the center of the lateral magnetic body, and originating from the center of the lateral magnetic body and pointing in a direction away from the center of rotation, be the reference vector of the lateral magnetic body. The magnetization direction vector is rotated relative to the reference vector toward the central magnetic body. The angle between the magnetization direction vector and the reference vector is less than 90°.

2. The rotation angle sensor as described in claim 1, wherein: Regarding each of the pair of lateral magnetic bodies, when the angle formed by the magnetization direction vector and the reference vector is θ, and the angle formed by the straight line connecting the center of the central magnetic body and the rotation center and the reference vector is φ, then θ = φ.

3. The rotation angle sensor as described in claim 1, wherein: Regarding each of the pair of lateral magnetic bodies, when the angle formed by the magnetization direction vector and the reference vector is θ, and the angle formed by the straight line connecting the center of the central magnetic body and the rotation center and the reference vector is φ, then θ < φ.

4. The rotation angle sensor as described in claim 1, wherein: Regarding each of the pair of lateral magnetic bodies, when the angle formed by the magnetization direction vector and the reference vector is θ, and the angle formed by the straight line connecting the center of the central magnetic body and the rotation center and the reference vector is φ, then θ > φ.

5. The rotation angle sensor according to any one of claims 1 to 4, wherein: The pair of lateral magnetic bodies are mirror-symmetric about the line connecting the center of the central magnetic body and the center of rotation.

6. The rotation angle sensor according to any one of claims 1 to 4, wherein: The central magnetic body and the pair of lateral magnetic bodies are magnets.

7. The rotation angle sensor according to any one of claims 1 to 4, wherein: The central magnetic body is a magnet, and the pair of lateral magnetic bodies are soft magnetic bodies magnetized by the central magnetic body.

8. The rotation angle sensor according to any one of claims 1 to 4, wherein: The pair of lateral magnetic bodies are magnets, and the central magnetic body is a soft magnetic body magnetized by the pair of lateral magnetic bodies.

9. The rotation angle sensor according to any one of claims 1 to 4, wherein: It has: a support body that rotates about the rotation center and supports the central magnetic body and the pair of lateral magnetic bodies.

10. The rotation angle sensor as claimed in claim 9, wherein: The support body is a circular plate, and the central magnetic body and the pair of lateral magnetic bodies are supported by any plane of the support body.

11. The rotation angle sensor as claimed in claim 9, wherein: The support is a flat plate, and the side of the support has an arc-shaped curved surface and a flat surface connecting the two ends of the curved surface. The central magnet and the pair of lateral magnets are supported by the flat surface.

12. The rotation angle sensor as claimed in claim 9, wherein: The support is a flat plate, and the side of the support has: an arc-shaped curved surface and a flat surface connecting the two ends of the curved surface. The rotation angle sensor has a soft magnetic body supported by the planar portion, and the central magnetic body and the pair of lateral magnetic bodies are supported by the soft magnetic body.

13. The rotation angle sensor as claimed in claim 12, wherein: The soft magnetic body is a flat plate, and the central magnetic body has a longer magnetization direction compared to the pair of lateral magnetic bodies.

14. The rotation angle sensor as claimed in claim 12, wherein: The soft magnetic body has: a flat plate portion and a protrusion extending radially outward from the flat plate portion, the central magnetic body being supported by the protrusion, and the pair of lateral magnetic bodies being supported by the flat plate portion.

15. The rotation angle sensor as claimed in claim 14, wherein: The central magnet has the same shape and size as the pair of lateral magnets.

16. The rotation angle sensor as claimed in claim 9, wherein: The support is a flat plate, and the side of the support has: an arc-shaped curved surface and a flat surface connecting the two ends of the curved surface. The rotation angle sensor has a support member supported by the support body. The support member has: a first plate portion supported by the planar portion, a second plate portion protruding radially outward from the first plate portion, and a third plate portion protruding radially inward from the first plate portion and supported by any plane of the support body. The central magnet and the pair of lateral magnets are supported by the first plate portion or the second plate portion.

17. The rotation angle sensor as claimed in claim 9, wherein: The support body is a flat plate and three support plates protruding from the flat plate. The side of the support body has an arc-shaped curved surface and a flat surface connecting the two ends of the curved surface. The three support plates protrude from the flat surface. The central magnet and the pair of lateral magnets are respectively supported by the three support plates.

18. The rotation angle sensor as claimed in claim 17, wherein: The support plate is a strip-shaped component bent into an L-shape. The central magnet and the pair of lateral magnets are located near the front end of the support plate and are supported by the surface of the support plate facing the opposite side to the rotation center.

19. The rotation angle sensor as claimed in claim 18, wherein: The support plate has the same thickness as the flat plate and is integrally formed with the flat plate.

20. The rotation angle sensor according to any one of claims 1 to 4, wherein: The central magnetic body and the pair of lateral magnetic bodies are cuboids.

21. A parking lock sensor, wherein: It has a rotation angle sensor as described in any one of claims 1 to 4.

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