Magnetic sensor, design method therefor, and assembly

Abstract

To provide a magnetic sensor in which detection errors due to the positional misalignment between a magnet and a magnetic field detection element is suppressed to apply a large magnetic field to the magnetic field detection element.SOLUTION: First to fourth magnets M1-M4 include first to fourth element facing surfaces S1-S4 each of which faces a magnetic field detection element 3, and first to fourth element facing surfaces S1-S4 respectively have a slender shape having first to fourth long axis A1-A4. When lines parallel to the first to fourth long axes A1-A4 and passing respectively through first to fourth quadrants I-IV, with origin 0 taken as an end, are taken as first to fourth virtual lines B1-B4, and angles formed counterclockwise by the first to fourth virtual lines B1-B4 with respect to a boundary line BX between the first quadrant I and the fourth quadrant IV are taken as θ1 to θ4, θ1 is in the range 0 degrees to 90 degrees, θ2 is in the range 90 degrees to 180 degrees, θ3 is in the range 180 degrees to 270 degrees, and θ4 is in the range 270 degrees to 360 degrees.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a magnetic sensor, a method for designing the same, and an assembly thereof. [Background technology]

[0002] Magnetic sensors that measure the rotation angle of a rotating body are known. Patent Document 1 discloses a magnetic sensor having four magnets arranged along the periphery of a rotor attached to a rotating shaft and a magnetoresistance effect element arranged away from the magnets. The four magnets are divided into two groups, and the two groups are arranged to sandwich a magnetic field detection element when viewed from a direction parallel to the central axis of rotation. Each of the two groups has two magnets adjacent to each other, and the surface of the magnet in one group facing the magnetic field detection element is a north pole, and the surface of the magnet in the other group facing the magnetic field detection element is a south pole. Patent Document 1 describes that the magnetic sensor configured in this way suppresses detection errors even if the magnet and the magnetic field detection element are misaligned in a direction perpendicular to the central axis of rotation due to an installation error. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-361119 A Summary of the Invention [Problem to be solved by the invention]

[0004] Although the magnetic sensor described in Patent Document 1 has the above-mentioned effects, the magnetic flux density applied to the magnetic field detection element is small. The object of the present invention is to provide a magnetic sensor that can suppress detection errors caused by misalignment between the magnet and the magnetic field detection element and can apply a large magnetic field to the magnetic field detection element. [Means for solving the problem]

[0005] The magnetic sensor has first to fourth magnets that are rotatable around a central axis of rotation and have a fixed positional relationship with each other, and a magnetic field detection element. In an XY coordinate system that is perpendicular to the central axis of rotation and passes through the origin, the first to fourth magnets are located in first to fourth quadrants, respectively, and the first to fourth magnets have first to fourth element facing surfaces that face the magnetic field detection element, respectively, and the first to fourth element facing surfaces have elongated shapes with first to fourth major axes. The first element facing surface and the second element facing surface have the same polarity, and the third element facing surface and the fourth element facing surface have a polarity different from that of the first and second element facing surfaces. The first to fourth virtual lines are straight lines that are parallel to the first to fourth major axes, have the origin as their end points, and pass through the first to fourth quadrants, and θ1 to θ4 are the angles that the first to fourth virtual lines make counterclockwise with respect to the boundary line between the first and fourth quadrants. θ1 is between 0 degrees and 90 degrees, θ2 is between 90 degrees and 180 degrees, θ3 is between 180 degrees and 270 degrees, and θ4 is between 270 degrees and 360 degrees. Effect of the Invention

[0006] According to the present invention, it is possible to provide a magnetic sensor in which detection errors due to misalignment between a magnet and a magnetic field detection element are suppressed and a large magnetic field can be applied to the magnetic field detection element. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a magnetic sensor according to an embodiment of the present invention; [Diagram 2] 2 is a plan view of first to fourth magnets of the magnetic sensor shown in FIG. 1. [Diagram 3] 3A to 3C are plan views showing examples of the arrangement of the first to fourth magnets. [Figure 4] FIG. 1 is a schematic diagram showing a comparison of a magnet according to an embodiment with other types of magnets. [Diagram 5] 5 is a graph showing the relationship between the Z direction distance H between the magnet and the element shown in FIG. 4 and the angle measurement error. [Figure 6] 13 is a graph showing the relationship between angle θ1, distance H in the Z direction, and angle measurement error. [Figure 7]13 is a graph showing the relationship between the aspect ratio, the Z direction distance H, and the angle measurement error. [Figure 8] 1 is a graph showing the relationship between angle θ1 and magnetic field strength. [Figure 9] 1 is a conceptual diagram showing the reason why the magnetic field strength increases in the range of θ1=0 to 90 degrees. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of the magnetic sensor of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are schematic diagrams of a magnetic sensor 1 according to an embodiment of the present invention. FIG. 1(a) is a perspective view of a rotating body 2 and a magnetic sensor 1, FIG. 1(b) is a side view of the rotating body 2, first to fourth magnets M1 to M4, and a magnetic field detection element 3, and FIG. 2 is a plan view of an end face 21 of the rotating body 2 and the first to fourth magnets M1 to M4 as viewed from the direction A in FIG. 1(b). The rotating body 2 is not particularly limited, but in this embodiment, it is a rotating shaft 2 of a motor 41 or an engine 42. The motor 41 or the engine 42 is connected to the rotating shaft 2 and drives the rotating shaft 2 to rotate. The magnetic sensor 1 and the motor 41, or the magnetic sensor 1 and the motor 41, constitute an assembly 100.

[0009] (Configuration of magnetic sensor 1) The magnetic sensor 1 includes first to fourth magnets M1 to M4, a magnetic field detection element 3, and a yoke 5. The first to fourth magnets M1 to M4 are supported by the yoke 5 and can rotate around the central axis C of rotation of the rotating shaft 2. The magnetic field detection element 3 is provided away from the rotating shaft 2 and the first to fourth magnets M1 to M4. The first to fourth magnets M1 to M4 are preferably made of the same material and preferably have the same shape and size. The yoke 5 is a plate-shaped member made of a single soft magnetic body and is fixed to the end surface 21 of the rotating shaft 2. The yoke 5 increases the strength of the magnetic field generated by the first to fourth magnets M1 to M4. Another structure (not shown) may be interposed between the yoke 5 and the end surface 21 of the rotating shaft 2. The first to fourth magnets M1 to M4 are sealed with a resin sealing material 6. The first to fourth magnets M1 to M4 are attracted to the yoke 5 by magnetic force and are further held by the sealing material 6, so that their relative positions are fixed. Instead of using the sealing material 6, the first to fourth magnets M1 to M4 may be fixed to the yoke 5 with an adhesive.

[0010] End face 21 of the rotating shaft 2, i.e., the mounting surface for the first to fourth magnets M1 to M4, is parallel to the XY coordinate system. The XY plane of the XY coordinate system is perpendicular to the central axis of rotation C, which passes through the origin 0 of the XY coordinate system. The X-axis and Y-axis are parallel to end face 21 of the rotating shaft 2 and perpendicular to each other. The Z-axis coincides with the central axis of rotation C of the rotating shaft 2 and is perpendicular to the X-axis and Y-axis. The directions parallel to the X-axis, Y-axis, and Z-axis may be referred to as the X-direction, Y-direction, and Z-direction, respectively.

[0011] The magnetic field detection section 31 of the magnetic field detection element 3 is composed of a magnetoresistance effect element (e.g., AMR element, TMR element, GMR element) or a Hall element. The magnetic field detection section 31 passes through the central axis of rotation C (Z-axis), but may be slightly offset from the Z-axis. The magnetic field detection element 3 is provided on a substrate 32, and the drive voltage and output signal of the magnetic field detection element 3 are input and output through the substrate 32. The magnetic field detection element 3 measures the magnetic field strength in two orthogonal directions (e.g., X direction and Y direction) in the XY coordinate system, but may also measure the magnetic field strength in one direction (e.g., X direction).

[0012] The magnetic sensor 1 generally operates as follows. The direction of the magnetic field applied to the magnetic field detection element 3 changes as the first to fourth magnets M1 to M4 rotate. That is, the strength of the magnetic field applied in the magnetic sensing direction of the magnetic field detection element 3 changes as the first to fourth magnets M1 to M4 rotate. By detecting this change in magnetic field strength, the magnetic sensor 1 can detect the rotation angle of the rotating shaft 2.

[0013] (Arrangement of first to fourth magnets M1 to M4) As shown in FIG. 2, the first to fourth magnets M1 to M4 are located in the first to fourth quadrants I to IV, respectively, in the XY coordinate system. The first to fourth magnets M1 to M4 have first to fourth element facing surfaces S1 to S4 facing the magnetic field detection element 3, respectively. The first to fourth element facing surfaces S1 to S4 have a long rectangular shape having a long side SA and a short side SB. The first to fourth element facing surfaces S1 to S4 have first to fourth long axes A1 to A4 parallel to the long side SA, respectively. The first element facing surface S1 and the second element facing surface S2 are N poles, and the third element facing surface S3 and the fourth element facing surface S4 are S poles. The first element facing surface S1 and the second element facing surface S2 may be S poles, and the third element facing surface S3 and the fourth element facing surface S4 may be N poles. That is, the first element facing surface S1 and the second element facing surface S2 have the same polarity, and the third element facing surface S3 and the fourth element facing surface S4 have a polarity different from that of the first and second element facing surfaces S1, S2. The yoke 5 contacts the back surfaces S5 (see FIG. 1(b)) of the first to fourth element facing surfaces S1 to S4 of the first to fourth magnets M1 to M4.

[0014] 1(b) is a parameter indicating the position of the magnetic field detection element 3 in the Z direction (the direction parallel to the central axis of rotation C), and is the Z direction distance between the first to fourth element opposing surfaces S1 to S4 and the magnetic field detection portion 31 of the magnetic field detection element 3. Note that in this embodiment, the Z direction positions of the first to fourth element opposing surfaces S1 to S4 are the same, but may be different.

[0015] Referring to FIG. 2, the first to fourth virtual lines B1 to B4 are parallel to the first to fourth long axes A1 to A4, have the origin 0 as an end, and pass through the first to fourth quadrants I to IV, respectively. In other words, the first to fourth virtual lines B1 to B4 are lines that are translated parallel to the first to fourth long axes A1 to A4, have the origin 0 as an end, and pass through the first to fourth quadrants I to IV, respectively. The angles that the first to fourth virtual lines B1 to B4 make counterclockwise with respect to the boundary line BX (the part of the X-axis where X≧0) between the first quadrant I and the fourth quadrant IV are θ1 to θ4. In this embodiment, the angle θ1 is 0 degrees or more and 90 degrees or less, the angle θ2 is 90 degrees or more and 180 degrees or less, the angle θ3 is 180 degrees or more and 270 degrees or less, and the angle θ4 is 270 degrees or more and 360 degrees or less.

[0016] The first long axis A1 and the second long axis A2 are line-symmetrical with respect to the Y axis, and the third long axis A3 and the fourth long axis A4 are line-symmetrical with respect to the Y axis. The first long axis A1 and the fourth long axis A4 are line-symmetrical with respect to the X axis, and the second long axis A2 and the third long axis A3 are line-symmetrical with respect to the X axis. In other words, if α2=180°-θ2, α3=θ3-180°, and α4=360°-θ4, then θ1=α2=α3=α4. In addition, the centers C1-C4 of the first to fourth element facing surfaces S1-S4 of the first to fourth magnets M1-M4 are preferably on a circle CC centered on the origin 0 in the XY coordinate system. With the above configuration, the magnetic flux is line-symmetrical with respect to the X axis and the Y axis, and the Z-direction component of the magnetic flux in the magnetic field detection element 3 is almost zero.

[0017] As described above, in this embodiment, once angle θ1 is determined, angles θ2 to θ4 are also determined. Therefore, the following description will focus on angle θ1. However, angles θ1 to θ4 may be different from one another within the above range. In addition, centers C1 to C4 of the first to fourth element facing surfaces S1 to S4 of the first to fourth magnets M1 to M4 do not have to be on a circle centered on the origin 0.

[0018] (Effects of this embodiment) FIG. 3 is a diagram similar to FIG. 2 showing the arrangement of the first to fourth magnets M1 to M4 for various angles θ1. FIG. 3(a) shows the case where θ1=0 degrees, FIG. 3(b) shows the case where θ1=30 degrees, FIG. 3(c) shows the case where θ1=60 degrees, and FIG. 3(d) shows the case where θ1=90 degrees. FIG. 3(e) is a comparative example showing the case where θ1=120 degrees. As shown in FIGS. 3(b) and (c), the angle θ1 may be greater than 0 degrees and less than 90 degrees, the angle θ2 may be greater than 90 degrees and less than 180 degrees, the angle θ3 may be greater than 180 degrees and less than 270 degrees, and the angle θ4 may be greater than 270 degrees and less than 360 degrees. For example, in the configuration shown in FIGS. 3(b) and (c), the short sides SB of the first to fourth element facing surfaces S1 to S4 face the rotation center axis C (origin 0).

[0019] FIG. 4 shows a comparison between this embodiment having four magnets M1 to M4 and other configurations. The magnet of Comparative Example 1 is disk-shaped, magnetized in the radial direction as a whole, with two semicircular parts each having a north pole and a south pole. The magnet of Comparative Example 2 is disk-shaped, with two semicircular parts each magnetized in the thickness direction, with the element-facing surface of one semicircular part being the north pole and the element-facing surface of the other semicircular part being the south pole. Comparative Example 3 has two rectangular magnets, with the element-facing surface of one magnet being the north pole and the element-facing surface of the other magnet being the south pole. Example 1 corresponds to the case where θ1=0 degrees in the above configuration.

[0020] In Comparative Example 1, the magnetic flux mainly enters and exits from the side of the magnet, so it tends to have a flat shape along the magnet. Therefore, when the Z-direction distance H between the magnetic field detection element 3 and the magnet is large, it is difficult to apply a sufficient magnetic field to the magnetic field detection element 3. In Comparative Example 2, the magnetic flux mainly enters and exits from the element-facing surface of the magnet, but the path of the magnetic flux is short, so it tends to have a low shape in the Z direction. Therefore, when the Z-direction distance H between the magnetic field detection element 3 and the magnet is large, it is difficult to apply a sufficient magnetic field to the magnetic field detection element 3. In Comparative Example 3, the magnetic flux mainly enters and exits from the element-facing surface of the magnet. Since the two magnets are separated, the magnetic flux is dispersed in the Z direction. Therefore, it is possible to apply a sufficient magnetic field to the magnetic field detection element 3 regardless of the Z-direction distance H between the magnetic field detection element 3 and the magnet. Example 1 shows the same tendency as Comparative Example 3.

[0021] Next, the angle measurement error will be described. Since the magnetic field detection element 3 and the first to fourth magnets M1 to M4 are attached to different structures, there is a possibility that mutual positional deviation may occur during assembly. Here, the positional deviation in the XY coordinate system is considered. Since the first to fourth magnets M1 to M4 rotate around the Z axis, the positional deviation may be considered as the radial deviation of the magnetic field detection element 3 from the Z axis. Therefore, for Comparative Examples 1 to 3 and Example 1, the magnetic field detection element 3 was shifted 1 mm in the radial direction from the Z axis, and the rotation angle detected by the magnetic sensor 1 was obtained while changing the rotation angle of the first to fourth magnets M1 to M4. Then, the maximum value of the difference between the calculated rotation angle and the actual rotation angle was obtained as the angle measurement error. The above calculation was performed for H = 3, 4, 5, 6, 7, 8 (mm). The dimensions and volumes of the magnets used in the calculation are shown in FIG. 4.

[0022] FIG. 5 shows the angle measurement errors thus obtained for Comparative Examples 1 to 3 and Example 1. In Comparative Examples 1 and 2, the angle measurement error increased as the Z direction distance H increased. In particular, the absolute value of the angle measurement error was large in Comparative Example 2. In Comparative Example 3, the angle measurement error was almost constant regardless of the Z direction distance H. In Example 1, the angle measurement error decreased as the Z direction distance H increased, and the angle measurement error was almost zero at H = 8 mm. This confirmed that Example 1 is effective when the Z direction distance H is relatively large.

[0023] (magnet aspect ratio) Next, the preferred range of the angle θ1 and the aspect ratio of the first to fourth element facing surfaces S1 to S4 (the ratio of the length of the long side SA to the length of the short side SB of the first to fourth element facing surfaces S1 to S4) will be described. FIG. 6 shows the relationship between the angle measurement error due to the positional deviation of the magnetic field detection element 3, the angles θ1 to θ4, and the Z-direction distance H. FIG. 6(a) shows the case of aspect ratio=1, FIG. 6(b) shows the case of aspect ratio=1.6, and FIG. 6(c) shows the case of aspect ratio=2.4. In each figure, the angle θ1 is changed in increments of 15 degrees from 0 degrees to 180 degrees. In the case of aspect ratio=1, the angle θ1 is not shown, but the angle measurement error hardly changes even when the angle θ1 is changed. In the case of aspect ratio=1.6, the angle measurement error also changes when the angle θ1 is changed, and in the case of aspect ratio=2.4, the angle measurement error changes even more when the angle θ1 is changed. This shows that it is easier to adjust angle measurement errors when the first to fourth element facing surfaces S1 to S4 are rectangular (with an aspect ratio exceeding 1) having a long side SA and a short side SB than when they are square.

[0024] FIG. 7 shows an example of a calculation of the relationship between the aspect ratio, the Z direction distance H, and the angle measurement error when θ1 = 30 degrees. The larger the aspect ratio, the easier it is to suppress the angle measurement error. However, as the aspect ratio becomes larger, not only does it increase the possibility that the first to fourth magnets M1 to M4 will be damaged, but it may also deteriorate the handling when fixing the first to fourth magnets M1 to M4 to the yoke 5. FIG. 7 shows examples with aspect ratios of 1.6 and 2.4, but it is preferable that the aspect ratio be between 1.2 and 2.5.

[0025] (Magnetic angle) Referring to Fig. 6(b) and Fig. 6(c), the graph of the angle measurement error shows a tendency to rise to the right as the Z-direction distance H increases. The graph is at the top when θ1 is around 0 to 15 degrees, and at the bottom when θ1 is around 90 to 105 degrees, and the graph of θ1 = 180 degrees coincides with the graph of θ1 = 0. The range of θ1 = 0 to 90 degrees and the range of θ1 = 90 to 180 degrees show roughly the same tendency, so there is not much difference between selecting the range of θ1 = 0 to 90 degrees or the range of θ1 = 90 to 180 degrees as the adjustment range of angle θ1 to suppress the angle measurement error. Comparing Fig. 6(b) and Fig. 6(c), the larger the aspect ratio is, the more widely the points where the angle measurement error becomes zero tend to vary in the horizontal axis direction (Z-direction distance H). This shows that the larger the aspect ratio is, the easier it is to adjust the Z-direction distance H to suppress the angle measurement error.

[0026] FIG. 8 shows the relationship between the Z-direction distance H and the magnetic field strength at the installation position of the magnetic field detection element 3. FIG. 8(a) shows the case of aspect ratio=1, FIG. 8(b) shows the case of aspect ratio=1.6, and FIG. 8(c) shows the case of aspect ratio=2.4. In each figure, the angle θ1 was changed in increments of 15 degrees from 0 degrees to 180 degrees. When the aspect ratio=1, the magnetic field strength was almost constant. When the aspect ratio=1.6, the magnetic field strength was maximum when θ1 was in the vicinity of 30 to 40 degrees and minimum when θ1 was in the vicinity of 120 to 130 degrees. When the aspect ratio=2.4 showed the same tendency as when the aspect ratio=1.6, and the maximum value of the magnetic field strength was larger than when the aspect ratio=1.6. From this, it was found that in order to suppress the angle measurement error and increase the magnetic field strength, it is preferable to select the range of θ1=0 to 90 degrees as the adjustment range of the angle θ1, and it is more preferable to set θ1 to be between 20 degrees and 50 degrees.

[0027] FIG. 9 conceptually shows the reason why the magnetic field strength increases in the range of θ1=0 to 90 degrees. FIG. 9(a) shows a plan view of a magnet arrangement (comparative example) where θ1 is more than 90 degrees and less than 180 degrees, and FIG. 9(b) shows a side view of the magnet arrangement. FIG. 9(c) shows a plan view of a magnet arrangement (present embodiment) where θ1 is 0 degrees or more and 90 degrees or less, and FIG. 9(d) shows a side view of the magnet arrangement. Since the amount of magnetic flux is considered to be proportional to the side length of the element facing surface, the magnetic flux entering and exiting the long side SA is shown with a thick line, and the magnetic flux entering and exiting the short side SB is shown with a thin chain line. These figures show only the magnetic flux passing near the magnetic field detection element 3. In the comparative example, the magnetic flux coming out of the long side SA of the two N poles repels each other and proceeds toward the S pole, and is absorbed by the long side SA of the two S poles. Since the path of the magnetic flux is relatively short, it does not rise much upward in the Z direction, and when the Z direction distance H is large, the magnetic field strength at the magnetic field detection element 3 becomes small.

[0028] The magnetic fluxes emitted from the short sides SB of the two N poles repel each other while first moving away from the magnetic field detection element 3, then reversing direction at point A and moving toward the S pole, passing the S pole and then reversing direction at point B and being absorbed by the short sides SB of the two S poles. Since the path of this magnetic flux is relatively long, it rises upward in the Z direction, and the magnetic field strength at the magnetic field detection element 3 becomes large. The magnetic field strength at the magnetic field detection element 3 is the sum of these two, but since there is little magnetic flux emitted from the short sides SB, the sum is small. In contrast, in the embodiment, the path of the magnetic flux is the same as in the comparative example, but since there is more magnetic flux emitted from the long sides SA, the magnetic field strength at the magnetic field detection element 3 also becomes large.

[0029] (Design method of magnetic sensor 1) As described above, the angle measurement error depends on the Z-direction distance H, but the Z-direction distance H is restricted by the configuration of the rotating body 2 to which the magnetic sensor 1 is attached and the surrounding arrangement. It may be difficult to adjust the Z-direction distance H, and the Z-direction distance H is often a given condition. On the other hand, as shown in Figs. 6(b) and 6(c), it is possible to make the angle measurement error zero by adjusting the angles θ1 to θ4. Specifically, the relationship between the angle measurement error, the angles θ1 to θ4, and the Z-direction distance H can be found as shown in Figs. 6 and 7, and the angles θ1 to θ4 can be determined according to the position (Z-direction distance H) of the magnetic field detection element 3 so that the angle measurement error is zero. It goes without saying that the magnetic sensor 1 manufactured according to this design method falls within the scope of the present invention.

[0030] (Additional Note) This specification includes the following disclosure. [Configuration 1] The magnetic field detecting element includes first to fourth magnets that are rotatable around a central axis of rotation and have a fixed positional relationship with each other, and a magnetic field detecting element. In an XY coordinate system that is perpendicular to the rotation axis and passes through the origin, the first to fourth magnets are located in first to fourth quadrants, respectively; the first to fourth magnets have first to fourth element facing surfaces facing the magnetic field detection elements, respectively, and the first to fourth element facing surfaces have elongated shapes having first to fourth major axes, respectively; the first element facing surface and the second element facing surface have the same polarity, and the third element facing surface and the fourth element facing surface have a polarity different from that of the first and second element facing surfaces; A magnetic sensor in which first to fourth virtual lines are straight lines that are parallel to the first to fourth major axes, have the origin as their end points, and pass through the first to fourth quadrants, and θ1 to θ4 are angles that the first to fourth virtual lines make counterclockwise with respect to the boundary line between the first quadrant and the fourth quadrant, where θ1 is between 0 degrees and 90 degrees, θ2 is between 90 degrees and 180 degrees, θ3 is between 180 degrees and 270 degrees, and θ4 is between 270 degrees and 360 degrees. [Configuration 2] The magnetic sensor of configuration 1, wherein θ1 is greater than 0 degrees and less than 90 degrees, θ2 is greater than 90 degrees and less than 180 degrees, θ3 is greater than 180 degrees and less than 270 degrees, and θ4 is greater than 270 degrees and less than 360 degrees. [Configuration 3] 3. The magnetic sensor of claim 2, wherein θ1=180 degrees-θ2=θ3-180 degrees=360 degrees-θ4. [Configuration 4] 4. The magnetic sensor according to configuration 3, wherein θ1 is equal to or greater than 20 degrees and equal to or less than 50 degrees. [Configuration 5] 5. The magnetic sensor according to any one of configurations 1 to 4, wherein short sides of the first to fourth element facing surfaces face the origin. [Configuration 6] 6. The magnetic sensor according to any one of configurations 1 to 5, wherein in the XY coordinate system, the centers of the first to fourth element facing surfaces are on a circle centered on the origin. [Configuration 7] The magnetic sensor according to any one of configurations 1 to 6, wherein the magnetic field detection element passes through the central axis of rotation. [Configuration 8] The magnetic sensor according to any one of configurations 1 to 7, wherein the first to fourth element facing surfaces are rectangular having long sides and short sides, and the ratio of the length of the long sides to the length of the short sides is 1.2 or more and 2.5 or less. [Configuration 9] 9. The magnetic sensor according to any one of configurations 1 to 8, further comprising one soft magnetic body in contact with a rear surface of each of the first to fourth element facing surfaces of the first to fourth magnets. [Configuration 10] 10. The magnetic sensor according to any one of configurations 1 to 9, further comprising a sealant that seals the first to fourth magnets. [Configuration 11] The magnetic sensor according to any one of configurations 1 to 10, a rotating shaft to which the first to fourth magnets of the magnetic sensor are fixed; a motor or engine connected to the rotatable shaft for driving the same in rotation. [Method 1] A method for designing a magnetic sensor comprising: first to fourth magnets rotatable around a central axis of rotation and having a fixed positional relationship with each other; and a magnetic field detection element, wherein in an XY coordinate system perpendicular to the central axis of rotation and passing through an origin, the first to fourth magnets are located in first to fourth quadrants, respectively, the first to fourth magnets have first to fourth element facing surfaces facing the magnetic field detection element, the first to fourth element facing surfaces have elongated shapes having first to fourth major axes, respectively, the first element facing surface and the second element facing surface have the same polarity, and the third element facing surface and the fourth element facing surface have a polarity different from that of the first and second element facing surfaces, determining a relationship between an angle measurement error due to a positional deviation of the magnetic field detection element in the XY coordinate system, θ1 to θ4, and a position of the magnetic field detection element in a direction parallel to the central axis of rotation, when first to fourth virtual lines are defined as straight lines that are parallel to the first to fourth major axes and have ends at the origin and pass through the first to fourth quadrants, and angles that the first to fourth virtual lines make in a counterclockwise direction with respect to a boundary line between the first quadrant and the fourth quadrant are defined as θ1 to θ4; determining θ1 to θ4 based on the positions of the magnetic field detection elements and the relationship so that the angle measurement error becomes zero. [Configuration 12] A magnetic sensor manufactured according to the magnetic sensor design method described in Method 1. [Explanation of symbols]

[0031] 1 Magnetic sensor 2 Rotating body (rotating shaft) 3 Magnetic field detection element 5. York 6. Encapsulating materials 100 assemblies A1~A4 1st to 4th major axes B1~B4 1st to 4th virtual lines C Rotational axis M1~M4 1st~4th magnets S1 to S4: First to fourth element facing surfaces θ1~θ4 angle

Claims

1. The magnetic field detecting element includes first to fourth magnets that are rotatable around a central axis of rotation and have a fixed positional relationship with each other, and a magnetic field detecting element; In an XY coordinate system that is perpendicular to the central axis of rotation and passes through the origin, the first to fourth magnets are located in first to fourth quadrants, respectively; the first to fourth magnets have first to fourth element facing surfaces facing the magnetic field detection element, respectively, and the first to fourth element facing surfaces have elongated shapes having first to fourth major axes, respectively; the first element facing surface and the second element facing surface have the same polarity, and the third element facing surface and the fourth element facing surface have a polarity different from that of the first and second element facing surfaces; A magnetic sensor in which first to fourth virtual lines are straight lines that are parallel to the first to fourth major axes, have the origin as their end points, and pass through the first to fourth quadrants, and angles that the first to fourth virtual lines make counterclockwise with respect to the boundary line between the first quadrant and the fourth quadrant are θ1 to θ4, where θ1 is between 0 degrees and 90 degrees, θ2 is between 90 degrees and 180 degrees, θ3 is between 180 degrees and 270 degrees, and θ4 is between 270 degrees and 360 degrees.

2. 2. The magnetic sensor according to claim 1, wherein θ1 is greater than 0 degrees and less than 90 degrees, θ2 is greater than 90 degrees and less than 180 degrees, θ3 is greater than 180 degrees and less than 270 degrees, and θ4 is greater than 270 degrees and less than 360 degrees.

3. 3. The magnetic sensor according to claim 2, wherein θ1=180 degrees-θ2=θ3-180 degrees=360 degrees-θ4.

4. 4. The magnetic sensor according to claim 3, wherein θ1 is equal to or greater than 20 degrees and equal to or less than 50 degrees.

5. 2. The magnetic sensor according to claim 1, wherein short sides of the first to fourth element facing surfaces face the origin.

6. 2. The magnetic sensor according to claim 1, wherein in the XY coordinate system, centers of the first to fourth element facing surfaces are on a circle having the origin as its center.

7. The magnetic sensor of claim 1 , wherein the magnetic field sensing element passes through the central axis of rotation.

8. 2. The magnetic sensor according to claim 1, wherein the first to fourth element facing surfaces are rectangular having long sides and short sides, and a ratio of the length of the long sides to the length of the short sides is 1.2 or more and 2.5 or less.

9. 2. The magnetic sensor according to claim 1, further comprising one soft magnetic body in contact with a rear surface of each of the first to fourth element facing surfaces of the first to fourth magnets.

10. 2. The magnetic sensor according to claim 1, further comprising a sealant that seals the first to fourth magnets.

11. A magnetic sensor according to any one of claims 1 to 10, a rotating shaft to which the first to fourth magnets of the magnetic sensor are fixed; a motor or engine connected to the rotatable shaft for driving the same in rotation.

12. A method for designing a magnetic sensor comprising: first to fourth magnets rotatable around a central axis of rotation and having a fixed positional relationship with each other; and a magnetic field detection element, wherein in an X-Y coordinate system perpendicular to the central axis of rotation and passing through an origin, the first to fourth magnets are located in first to fourth quadrants, respectively, the first to fourth magnets have first to fourth element facing surfaces facing the magnetic field detection element, the first to fourth element facing surfaces have elongated shapes each having first to fourth major axes, respectively, the first element facing surface and the second element facing surface have the same polarity, and the third element facing surface and the fourth element facing surface have a polarity different from that of the first and second element facing surfaces, determining a relationship between an angle measurement error due to a positional deviation of the magnetic field detection element in the X-Y coordinate system, θ1 to θ4, and a position of the magnetic field detection element in a direction parallel to the central axis of rotation, when first to fourth virtual lines are defined as straight lines that are parallel to the first to fourth major axes and have ends at the origin and pass through the first to fourth quadrants, and angles that the first to fourth virtual lines make in a counterclockwise direction with respect to a boundary line between the first quadrant and the fourth quadrant are defined as θ1 to θ4; determining θ1 to θ4 based on the positions and the relationship of the magnetic field detection elements so that the angle measurement error becomes zero.

13. A magnetic sensor manufactured according to the method for designing a magnetic sensor according to claim 12.

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