Rotation angle detection device

Abstract

The present invention relates to a rotation angle detection device (1), comprising: a correction target driven gear (32), which is a driven gear meshing with a main drive gear (31); a first sensor (37) configured to generate an electrical signal based on the rotation of the correction target driven gear (32); and an electronic control unit (100) that calculates the driven-side rotation angle based on the electrical signal. The electronic control unit (100) is configured to store a correction angle, which is used to correct the driven-side rotation angle when calculating the driven-side rotation angle. The correction is a predetermined deviation in a predetermined angle range, which is an average value obtained by averaging deviations of an integer quantity corresponding to the same relative rotation angle, thereby serving as a deviation in the angle range of 0 degrees to 360 degrees.

Description

Technical Field

[0001] This invention relates to a rotation angle detection device. Background Technology

[0002] Japanese Unexamined Patent Application Publication No. 2006-29937 (JP 2006-29937 A) discloses a rotation angle detection device for detecting the rotation angle of a rotating shaft. The rotation angle detection device described in JP 2006-29937 A includes a first gear, a second gear, and a third gear. The first gear serves as a main drive gear that rotates integrally with the rotating shaft, the second gear serves as a driven gear meshing with the first gear, and the third gear serves as a driven gear meshing with the second gear. The number of teeth on the two driven gears is set to be less than the number of teeth on the main drive gear. The number of teeth on the two driven gears is also different from each other, and the two driven gears are arranged such that when the main drive gear rotates, the rotation angles of the two driven gears are different from each other. A calculation unit detects the rotation angle of the driven gears using sensors corresponding to each of the two driven gears, and calculates the rotation angle of the main drive gear, i.e., the rotation angle of the rotating shaft, based on these detected rotation angles.

[0003] The accuracy of calculating the rotation angle of the main drive gear is reduced due to electrical errors in the sensor output and mechanical errors in the gear. In the rotation angle detection device described in JP 2006-29937 A, the deviation between the actual rotation angle of the main drive gear caused by such errors and the calculated rotation angle of the main drive gear is stored as a correction angle, and this correction angle is used to correct the rotation angle of the main drive gear when calculating the rotation angle of the main drive gear. Summary of the Invention

[0004] Some calculation units that calculate the rotation angle of the driven gear have a function to correct the detected rotation angle of the driven gear in an angle range of 0 to 360 degrees. These calculation units acquire the deviation in the angle range of 0 to 360 degrees and store the deviation as a correction angle. However, in an angle range of more than 360 degrees where the driven gear rotates more than one revolution, it is difficult to improve the detection accuracy of the driven gear rotation angle by correcting the rotation angle of the driven gear using the stored correction angle. For example, for a certain rotation angle of 180 degrees and a certain rotation angle of 540 degrees of the driven gear, the calculation unit uses the same correction angle to perform the correction of the rotation angle of the driven gear, where the rotation angle of 540 degrees of the driven gear is the rotation angle of the driven gear after rotating one more revolution from the rotation angle of 180 degrees, and the rotation angle of 540 degrees is also 180 degrees. However, even if the relative rotation angle of the driven gear between the first and second revolutions is the same 180 degrees, the meshing positions of the main drive gear and the driven gear are different. Therefore, sometimes the rotation angle of the driven gear should be corrected with different correction angles for the first and second revolutions. In this case, using a stored correction angle to correct the rotation angle of the driven gear may result in a greater difference between the corrected rotation angle and the actual rotation angle of the driven gear than the difference between the uncorrected rotation angle and the actual rotation angle, and the detection accuracy of the driven gear's rotation angle will decrease. Therefore, a rotation angle detection device is needed that can properly correct the detected rotation angle of the driven gear and improve the detection accuracy of the driven gear's rotation angle.

[0005] One aspect of the present invention is a rotation angle detection device. The rotation angle detection device includes: a correction target driven gear, which is a driven gear meshing with a main drive gear, the main drive gear being disposed on a rotating shaft for integral rotation with the rotating shaft; a first sensor configured to generate an electrical signal based on the rotation of the correction target driven gear; and an electronic control unit configured to calculate a driven-side rotation angle based on the electrical signal generated by the first sensor, the driven-side rotation angle being the rotation angle of the correction target driven gear. The number of teeth of the correction target driven gear is obtained by dividing the number of teeth of the main drive gear by an integer. The electronic control unit is configured to store a correction angle, which is used to correct the driven-side rotation angle when calculating the driven-side rotation angle. The correction angle is a predetermined deviation in a predetermined angle range, obtained by averaging deviations equal to the integer value and corresponding to the same relative rotation angle, thereby serving as a deviation in an angle range of 0 degrees to 360 degrees. The predetermined deviation is the deviation obtained within a predetermined angular range and is the deviation between the driven-side rotation angle and the actual rotation angle of the driven gear of the correction object. The driven-side rotation angle is obtained over the entire angular range when the driven gear of the correction object has rotated a number of revolutions equal to the integer value.

[0006] The correction angle stored in the electronic control unit is an average value obtained by averaging the deviations corresponding to the same relative rotation angle, with the number equal to the integer value. When obtaining the correction angle, deviations in the 0 to 360 degree angle range are considered, as well as deviations in the angle range exceeding 360 degrees. This driven-side rotation angle is corrected based on the correction angle obtained by also considering deviations in the angle range exceeding 360 degrees, and therefore, the driven-side rotation angle can be corrected more appropriately as a whole compared to when the driven-side rotation angle is corrected based solely on the correction angle obtained based on deviations in the 0 to 360 degree angle range. For example, the correction angle when the driven gear's rotation angle is 540 degrees is usually set based on the deviation when the driven gear's rotation angle is 180 degrees, without considering the deviation when the driven gear's rotation angle is 540 degrees. On the other hand, according to the above configuration, the correction angle when the driven gear's rotation angle is 540 degrees considers both the deviation when the driven gear's rotation angle is 180 degrees and the deviation when the driven gear's rotation angle is 540 degrees. Therefore, it is possible to suppress the difference between the corrected driven-side rotation angle and the actual rotation angle of the driven gear to be greater than the difference between the original driven-side rotation angle and the actual rotation angle of the driven gear. Thus, the driven-side rotation angle can be corrected more appropriately.

[0007] The rotation angle detection device may further include: a self-calibrating driven gear, which is a different driven gear from the calibration target driven gear and meshes with the main drive gear; and a second sensor configured to generate an electrical signal based on the rotation of the self-calibrating driven gear. The number of teeth of the calibration target driven gear and the number of teeth of the self-calibrating driven gear may be different from each other. The electronic control unit may be configured to calculate the rotation angle of the self-calibrating driven gear based on the electrical signal generated by the second sensor, and may be configured not to perform calibration on the rotation angle of the self-calibrating driven gear based on the calibration angle.

[0008] Based on the above configuration, providing a driveless gear with a different number of teeth than the driven gear being calibrated allows information to be provided when obtaining the rotation angle and number of rotations of the main drive gear. This information allows the rotation angle of the main drive gear to be obtained as an absolute angle.

[0009] The rotation angle detection device may further include a biasing member configured to bias the driven gear to be corrected toward the main drive gear. According to this configuration, by biasing the driven gear toward the main drive gear, meshing between the main drive gear and the driven gear can be adequately ensured. However, in the rotation angle detection device with the biasing member, by biasing the driven gear toward the main drive gear, hysteresis at the driven gear is suppressed, and therefore the state of the teeth of the main drive gear has a greater influence on the calculation of the driven-side rotation angle. For example, compared to not biasing the driven gear toward the main drive gear, when the driven gear is biased toward the main drive gear, there may be a difference where the driven-side rotation angle before correction is larger than the actual rotation angle of the driven gear to be corrected within the angle range of 0 to 360 degrees, and on the other hand, there may be a difference where the driven-side rotation angle before correction is smaller than the actual rotation angle of the driven gear to be corrected within the angle range exceeding 360 degrees. In this case, conventionally, the driven-side rotation angle is corrected based solely on a correction angle obtained from the deviation within the 0-360 degree angular range. Therefore, the driven-side rotation angle is corrected to suppress any discrepancies where the driven-side rotation angle before correction within the 0-360 degree angular range is larger than the actual rotation angle of the driven gear being corrected. However, when the same correction angle is used to correct the driven-side rotation angle in an angular range exceeding 360 degrees, and thus any discrepancies where the driven-side rotation angle before correction is smaller than the actual rotation angle of the gear being corrected are corrected, this correction makes the small discrepancy larger. Rotation angle detection devices equipped with biasing members exhibit this characteristic, and therefore, using a correction angle that also considers deviations within the angular range exceeding 360 degrees can appropriately produce the advantageous effect of more properly correcting the driven-side rotation angle.

[0010] The rotation angle detection device may also include a torque sensor configured to detect the torque acting on the rotation shaft. According to this configuration, information related not only to the rotation angle of the driven side but also to the torque acting on the rotation shaft can be provided.

[0011] Based on the above configuration, the rotation angle of the driven gear to be tested can be corrected more appropriately, and the detection accuracy of the rotation angle of the driven gear can be improved. Attached Figure Description

[0012] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals denote the same elements, and in the drawings:

[0013] Figure 1 It is a cross-sectional view of the detection device taken along a plane that includes a line orthogonal to the axis of the pinion shaft and is located between the support member and the cover;

[0014] Figure 2 It is a cross-sectional view of the detection device taken along the plane described below, which includes the axis of the pinion shaft and includes a line at the midpoint between the axis of the first driven gear and the axis of the second driven gear;

[0015] Figure 3 This is a schematic 3D diagram of a torque sensor;

[0016] Figure 4 It is a block diagram illustrating the schematic configuration of the sensor, microcomputer, and control device;

[0017] Figure 5 It is a graph illustrating the relationship between the first driven side rotation angle, the second driven side rotation angle, and the absolute angle of the pinion shaft;

[0018] Figure 6 It is a graph illustrating the relationship between the first driven side rotation angle before correction and the correction angle in the angular range of 0 degrees to 360 degrees;

[0019] Figure 7 It is a graph illustrating the relationship between the rotation angle of the first driven side before correction and the actual rotation angle of the first driven gear in the full angular range;

[0020] Figure 8 It is a graph showing the deviation between the first driven side rotation angle before correction and the actual rotation angle of the first driven gear over the entire angular range; and

[0021] Figure 9It is a graph of the deviation between the corrected first driven side rotation angle and the actual rotation angle of the first driven gear in the full angular range, wherein the solid line represents the embodiment of the present invention, and the dashed line represents the conventional arrangement for correcting the first driven side rotation angle based on the correction angle obtained by using only the deviation in the angular range of 0 degrees to 360 degrees. Detailed Implementation

[0022] Embodiments of the detection device will be described with reference to the accompanying drawings. For example, such as... Figure 1 and Figure 2 As shown, the detection device 1 is installed in the vehicle's steering system. The pinion shaft 2, serving as the rotation shaft, constitutes the steering shaft connected to the steering wheel. The detection device 1 is a torque angle sensor device, a combination of a torque sensor and a rotation angle sensor. The torque sensor detects the torque applied to the pinion shaft 2 by the steering operation of the steering wheel as the steering torque, and the rotation angle sensor detects the absolute angle θpa, which is the rotation angle of the pinion shaft 2 during multiple rotations exceeding 360 degrees.

[0023] The detection device 1 has a sensor housing 10. The sensor housing 10 is attached to a gear housing 3 that houses a pinion shaft 2. The sensor housing 10 has an insertion portion 11 and a receiving portion 12 that are in communication with each other. The insertion portion 11 has a cylindrical shape, and the axis of the insertion portion 11 extends in the axial direction X of the pinion shaft 2. The pinion shaft 2 is inserted through the insertion portion 11. The pinion shaft 2 has an input shaft on the steering wheel side, an output shaft on the steering wheel side, and a torsion bar connecting the input shaft and the output shaft, with the steering wheel side being the opposite side of the steering wheel. The receiving portion 12 has a box shape and protrudes from the side of the insertion portion 11 in a direction intersecting the axial direction X. The receiving portion 12 is open in the direction intersecting the axial direction X. The opening 12a of the receiving portion 12 is closed by a cover 13.

[0024] A torque sensor 20 and a rotation angle sensor 30 are disposed inside the sensor housing 10, such as Figure 2 As shown. The torque sensor 20 has a first magnetic yoke 21, a second magnetic yoke 22, a first magnetic ring 23, a second magnetic ring 24, a first torque detection magnetic sensor 25, a second torque detection magnetic sensor 26, and a multipole magnet 27, as shown. Figure 3 As shown.

[0025] A multipole magnet 27 is fixed to the input shaft of the pinion shaft 2, allowing it to rotate integrally with the input shaft. The multipole magnet 27 has a cylindrical shape, with S and N poles arranged alternately along its circumferential direction. The output shaft of the pinion shaft 2 has a cylindrical portion extending toward the input shaft side, thereby covering the input shaft. A first yoke 21 and a second yoke 22 are fixed to the cylindrical portion of the output shaft of the pinion shaft 2. The multipole magnet 27 is located inside the first yoke 21 and the second yoke 22 in the radial direction. The first yoke 21 and the second yoke 22 form a magnetic circuit based on the magnetic field of the multipole magnet 27.

[0026] The first magnetic yoke 21 has an annular disk-shaped portion 21a and a plurality of plate-shaped teeth 21b. The teeth 21b are arranged at equal intervals along the inner peripheral edge of the annular portion 21a. The teeth 21b extend along the axial direction X of the pinion shaft 2. Similar to the first magnetic yoke 21, the second magnetic yoke 22 has an annular disk-shaped portion 22a and a plurality of teeth 22b. The teeth 22b are arranged at equal intervals along the inner peripheral edge of the annular portion 22a. The teeth 22b extend along the axial direction X of the pinion shaft 2. The teeth 21b of the first magnetic yoke 21 and the teeth 22b of the second magnetic yoke 22 extend in opposite directions to each other in the axial direction X of the pinion shaft 2, and are also arranged alternately in the circumferential direction.

[0027] The first magnetic ring 23 and the second magnetic ring 24 are arranged side by side in the axial direction X of the pinion shaft 2. The first magnetic ring 23 and the second magnetic ring 24 are attached to the inside of the sensor housing 10. The first magnetic ring 23 is arranged around the first magnetic yoke 21. The second magnetic ring 24 is arranged around the second magnetic yoke 22. The first magnetic ring 23 senses the magnetic flux from the first magnetic yoke 21. The second magnetic ring 24 senses the magnetic flux from the second magnetic yoke 22.

[0028] The first magnetic ring 23 includes a first ring portion 23a and a first magnetic collecting portion 23b. The first ring portion 23a is configured in a C-shape, curved along the outer peripheral surface of the first magnetic yoke 21. The first magnetic collecting portion 23b has two fixing portions 23c and 23d, a connecting portion 23e, and two first magnetic collecting protrusions 23f and 23g. The two fixing portions 23c and 23d are attached to the outer peripheral surface of the first ring portion 23a. The two fixing portions 23c and 23d are curved along the outer peripheral surface of the first ring portion 23a. The connecting portion 23e connects the two fixing portions 23c and 23d. A gap is provided between the surface of the connecting portion 23e facing the first ring portion 23a and the outer peripheral surface of the first ring portion 23a. The two first magnetic collecting protrusions 23f and 23g are provided at the end portions of the connecting portion 23e facing the second magnetic ring 24. The two first magnetic protrusions 23f and 23g extend outward in the radial direction toward the first ring portion 23a.

[0029] The second magnetic ring 24 has a second ring portion 24a and two second magnetic protrusions 24b and 24c. The second ring portion 24a is configured in a letter-C shape, curved along the outer peripheral surface of the second magnetic yoke 22. The two second magnetic protrusions 24b and 24c extend outward in the radial direction toward the second ring portion 24a. The two second magnetic protrusions 24b and 24c face the two first magnetic protrusions 23f and 23g of the first magnetic ring 23 in the axial direction X of the pinion shaft 2. A first torque detection magnetic sensor 25 is placed between the first magnetic protrusion 23f and the second magnetic protrusion 24b. A second torque detection magnetic sensor 26 is placed between the first magnetic protrusion 23g and the second magnetic protrusion 24c. The first torque detection magnetic sensor 25 and the second torque detection magnetic sensor 26 are arranged on a plate 35, which will be described later. The first torque detection magnetic sensor 25 and the second torque detection magnetic sensor 26 are magnetic sensors for detecting the magnetic flux sensed in the first magnetic ring 23 and the second magnetic ring 24. For example, Hall effect sensors are used as the first torque detection magnetic sensor 25 and the second torque detection magnetic sensor 26.

[0030] When the torsion bar of the pinion shaft 2 undergoes torsional deformation due to the operation of the steering wheel, the relative positions of the multipole magnet 27 and the first yoke 21 in the rotational direction, as well as the relative positions of the multipole magnet 27 and the second yoke 22 in the rotational direction, change. This alters the magnetic flux density guided from the multipole magnet 27 to the first magnetic ring 23 via the first yoke 21. The magnetic flux density guided from the multipole magnet 27 to the second magnetic ring 24 via the second yoke 22 also changes.

[0031] like Figure 4 As shown, a first torque detection magnetic sensor 25 is connected to a first torque detection calculation unit 25a. A second torque detection magnetic sensor 26 is connected to a second torque detection calculation unit 26a. The first torque detection magnetic sensor 25 generates an electrical signal St1 based on the magnetic flux density. Based on the electrical signal St1 generated by the first torque detection magnetic sensor 25, the first torque detection calculation unit 25a calculates the torque acting on the torsion bar as a first steering torque Th1. Furthermore, the second torque detection magnetic sensor 26 generates an electrical signal St2 based on the magnetic flux density. Based on the electrical signal St2 generated by the second torque detection magnetic sensor 26, the second torque detection calculation unit 26a calculates the torque acting on the torsion bar as a second steering torque Th2.

[0032] The rotation angle sensor 30 includes a main drive gear 31, a first driven gear 32, a second driven gear 33, a support member 34, a plate 35, an offset member 36, a first rotation angle detection magnetic sensor 37, and a second rotation angle detection magnetic sensor 38, as shown below. Figure 1 and Figure 2 As shown.

[0033] The main drive gear 31 is mounted on the input shaft of the pinion shaft 2 so that it can rotate integrally with the input shaft of the pinion shaft 2. The main drive gear 31 has a cylindrical shape and has a plurality of teeth 31a provided on its outer circumferential surface, and the input shaft of the pinion shaft 2 is fitted onto the inner circumferential surface of the main drive gear 31. The number of teeth 31a provided on the outer circumferential surface of the main drive gear 31 is, for example, set to 48 teeth.

[0034] Plate 35 is attached to the inner bottom surface of the receiving portion 12 of the sensor housing 10. Support member 34 rotatably supports the first driven gear 32 and the second driven gear 33. Support member 34 is attached to the inner bottom surface of the receiving portion 12 of the sensor housing 10. A gap is provided between the middle portion of support member 34 and the inner bottom surface of the receiving portion 12, and plate 35 is fitted between support member 34 and the inner bottom surface of the receiving portion 12. Support member 34 is in the form of a rectangular plate. The long side 34a of support member 34 faces the main drive gear 31. A first support hole 50 and a second support hole 51 are provided in support member 34. The first support hole 50 and the second support hole 51 are holes in support member 34 extending in the axial direction X of the pinion shaft 2. The first support hole 50 is located near a first corner on one side of support member 34, where a first short side 34b intersects with the long side 34a located on the side of the main drive gear 31. The second support hole 51 is located near the second corner on the other side of the support member 34, where the second short side 34c intersects the long side 34a located on the main drive gear 31 side. When viewed in the axial direction X of the pinion shaft 2, the first support hole 50 and the second support hole 51 are shaped as grooves extending radially along the main drive gear 31. The separation distance between the first support hole 50 and the second support hole 51 is the shortest on the main drive gear 31 side, and the further away from the main drive gear 31, the longer the separation distance between the first support hole 50 and the second support hole 51.

[0035] The first driven gear 32 has a disc-shaped gear portion 61 and a cylindrical shaft portion 62. A plurality of teeth 61a are provided on the outer peripheral surface of the gear portion 61. The teeth 61a of the gear portion 61 mesh with the teeth 31a of the main drive gear 31. The number of teeth 61a provided on the outer peripheral surface of the gear portion 61 is, for example, set to 24 teeth. In other words, the number of teeth 61a of the first driven gear 32 is half (1 / 2) of the number of teeth 31a of the main drive gear 31. One end face of the shaft portion 62 is connected to the center of the face of the gear portion 61 facing the plate 35. The outer diameter of the shaft portion 62 is set to be smaller than the outer diameter of the gear portion 61. A recessed portion 62a is provided on the other end face of the shaft portion 62 facing the plate 35. The recessed portion 62a has a circular cross-sectional shape at a cross-section taken from the shaft portion 62 in a direction orthogonal to the axial direction X. A disc-shaped first permanent magnet 62b is arranged in the recessed portion 62a. The first permanent magnet 62b is magnetized such that magnetic poles of different polarities are alternately arranged in the circumferential direction of the first permanent magnet 62b. When the main drive gear 31 rotates, the first permanent magnet 62b, which is disposed on the first driven gear 32 meshing with the main drive gear 31, rotates. The first driven gear 32 is an example of the "correction object driven gear" in the claim.

[0036] The second driven gear 33 has a disc-shaped gear portion 63 and a columnar shaft portion 64. The teeth 63a of the gear portion 63 mesh with the teeth 31a of the main drive gear 31. The number of teeth 63a on the outer circumferential surface of the gear portion 63 is different from the number of teeth 61a of the gear portion 61 of the first driven gear 32, and is, for example, set to 26 teeth. A recessed portion 64a is provided on the other end face of the shaft portion 64 facing the plate 35. The recessed portion 64a has a circular cross-sectional shape at a cross-section taken along a direction orthogonal to the axial direction X of the shaft portion 64. A disc-shaped second permanent magnet 64b is arranged in this recessed portion 64a. Except that the number of teeth 63a of the gear portion 63 of the second driven gear 33 is different from the number of teeth 61a of the gear portion 61 of the first driven gear 32, the first driven gear 32 and the second driven gear 33 have the same shape. When the main drive gear 31 rotates, the second permanent magnet 64b, which is mounted on the second driven gear 33 that meshes with the main drive gear 31, rotates. The second driven gear 33 is an example of the "correction-free driven gear" in the claims.

[0037] A plate-shaped stop 53 is mounted on the support member 34. The stop 53 covers the surface of the support member 34 that is opposite to the plate 35. The movement of the first driven gear 32 and the second driven gear 33 toward the opposite side of the plate 35 is restricted by the gear portion 61 and the gear portion 63 abutting against the stop 53.

[0038] A columnar support portion 52 is provided on the surface of the supporting member 34 opposite to that of the plate 35, such as... Figure 1 As shown. The support portion 52 is positioned between the first support hole 50 and the second support hole 51 in the longitudinal direction of the support member 34, and is positioned further from the main drive gear 31 in the transverse direction of the support member 34 than from the first support hole 50 and the second support hole 51. The biasing member 36 is supported by the support member 34 by being mounted to the support portion 52. A metal torsion coil spring is used as the biasing member 36.

[0039] The biasing member 36 has a generally V-shaped overall shape. The biasing member 36 has a coil portion 36a disposed in its middle portion by multiple windings, and also has a first arm portion 36b and a second arm portion 36c extending linearly at both ends. The annular coil portion 36a is mounted by inserting a support portion 52 into the annular coil portion 36a. The first arm portion 36b is connected to one end of the coil portion 36a, and the second arm portion 36c is connected to the other end of the coil portion 36a. The first arm portion 36b abuts against the side of the shaft portion 62 located opposite to the main drive gear 31. The second arm portion 36c abuts against the side of the shaft portion 64 located opposite to the main drive gear 31. The first arm portion 36b and the second arm portion 36c elastically deform to reduce the angle between the first arm portion 36b and the second arm portion 36c centered on the coil portion 36a. Shaft portions 62 and 64 are typically biased toward the main drive gear 31 by the elastic force of the biasing member 36.

[0040] The first rotation angle detection magnetic sensor 37 is mounted on the surface of the plate 35 facing the first driven gear 32, such as... Figure 2 As shown. A first rotation angle detection magnetic sensor 37 faces the first permanent magnet 62b in the axial direction X. A second rotation angle detection magnetic sensor 38 is mounted on the surface of the plate 35 facing the second driven gear 33. The second rotation angle detection magnetic sensor 38 faces the second permanent magnet 64b in the axial direction X. The first rotation angle detection magnetic sensor 37 and the second rotation angle detection magnetic sensor 38 are magnetic sensors for detecting the magnetic flux from the first permanent magnet 62b and the second permanent magnet 64b. For example, a Hall sensor is used as the first rotation angle detection magnetic sensor 37 and the second rotation angle detection magnetic sensor 38. The first rotation angle detection magnetic sensor 37 is an example of the "first sensor" in the claim. The second rotation angle detection magnetic sensor 38 is an example of the "second sensor" in the claim.

[0041] The first rotation angle detection magnetic sensor 37 is connected to the first rotation angle detection calculation unit 37a, such as... Figure 4As shown. A first rotation angle detection magnetic sensor 37 generates an electrical signal Sg1 based on the magnetic flux density input from the first permanent magnet 62b. A first rotation angle detection calculation unit 37a calculates a first driven-side rotation angle θg1 based on the electrical signal Sg1 generated by the first rotation angle detection magnetic sensor 37, where the first driven-side rotation angle θg1 is the rotation angle of the first driven gear 32. A second rotation angle detection magnetic sensor 38 is connected to a second rotation angle detection calculation unit 38a. The second rotation angle detection magnetic sensor 38 generates an electrical signal Sg2 based on the magnetic flux density input from the second permanent magnet 64b. The second rotation angle detection calculation unit 38a calculates a second driven-side rotation angle θg2 based on the electrical signal Sg2 generated by the second rotation angle detection magnetic sensor 38, where the first driven-side rotation angle θg1 is the rotation angle of the second driven gear 33. A first torque detection calculation unit 25a, a second torque detection calculation unit 26a, a first rotation angle detection calculation unit 37a, and a second rotation angle detection calculation unit 38a constitute a microcomputer 100. The detection device 1 is an example of the "rotation angle detection device" in the claims. When calculating the first driven-side rotation angle θg1, the detection device 1 corrects the first driven-side rotation angle θg1, and is equipped with a first driven gear 32, a first rotation angle detection magnetic sensor 37, and a microcomputer 100. Furthermore, the microcomputer 100 is an example of the "electronic control unit" in the claims.

[0042] Microcomputer 100 is connected to control device 110. Microcomputer 100 provides control device 110 with a calculated first driven-side rotation angle θg1 and a second driven-side rotation angle θg2. Control device 110 acquires the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2 calculated by microcomputer 100. Control device 110 calculates the rotation angle of the main drive gear 31, i.e., the rotation angle of the pinion shaft 2, based on the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2, as the absolute angle θpa. More specifically, control device 110 uses the arctangent value obtained according to the first driven-side rotation angle θg1 and the arctangent value obtained according to the second driven-side rotation angle θg2 to calculate the absolute angle θpa of the pinion shaft 2. (Refer to...) Figure 5 The calculation of the absolute angle θpa performed by the control device 110 is described.

[0043] Figure 5The vertical axis of the graph represents the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2, while the horizontal axis represents the absolute angle θpa of the pinion shaft 2. The solid line represents the change in the first driven-side rotation angle θg1, and the dashed line represents the change in the second driven-side rotation angle θg2. Note that the first rotation angle detection magnetic sensor 37 and the second rotation angle detection magnetic sensor 38 each have the same 1x shaft angle multiplier. As the pinion shaft 2 rotates, the phase of the waveform of the first driven-side rotation angle θg1 (represented by the solid line) and the phase of the waveform of the second driven-side rotation angle θg2 (represented by the dashed line) deviate due to the difference in the number of teeth 61a of the first driven gear 32 and the number of teeth 63a of the second driven gear 33. Note that the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2 are relative angles that can be detected by the first rotation angle detection magnetic sensor 37 and the second rotation angle detection magnetic sensor 38, which are respectively relative angle sensors, i.e., the angle range from 0 degrees to 360 degrees. Therefore, the rotation angle θg1 of the first driven side alone or the rotation angle θg2 of the second driven side alone cannot be interpreted as how many revolutions have been made to reach the current rotation angle, and the absolute angle θpa of the rotation angle in the multiple revolutions of the pinion shaft 2 cannot be obtained.

[0044] The control device 110 calculates the angle difference between the first driven side rotation angle θg1 and the second driven side rotation angle θg2. Figure 5 The thick solid line in the graph represents the absolute value of the angle difference between the first driven side rotation angle θg1 and the second driven side rotation angle θg2.

[0045] The control device 110 calculates the number of rotations γ of the first driven gear 32 based on the angle difference between the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2, using a table omitted in the illustration. The number of rotations γ is an integer value representing how many cycles of electrical signals the first rotation angle detection magnetic sensor 37 has generated relative to the current cycle; that is, how many times the angle domain that the first rotation angle detection magnetic sensor 37 can detect has been repeated. The table defines the relationship between three items: the angle difference between the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2, the tolerance range of this angle difference, and the number of rotations γ of the first driven gear 32. This table defines these three items for each 360 degrees across the entire angle domain for calculating the absolute angle θpa, i.e., the angle domain that the first rotation angle detection magnetic sensor 37 can detect. Based on the angle difference between the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2, the control device 110 determines the item in the table to which the angle difference belongs and detects the corresponding number of rotations γ.

[0046] The control device 110 calculates the absolute angle θpa based on the first driven side rotation angle θg1 of the first driven gear 32 and the number of rotations γ of the first driven gear 32. The absolute angle θpa is the rotation angle of the pinion shaft 2 for more than 360 degrees of multiple rotations, for example, based on the following expression (1).

[0047] θpa=mα / z+(m / z)Ωγ (1)

[0048] Here, "m" is the number of teeth 61a of the first driven gear 32, "z" is the number of teeth 31a of the main drive gear 31, "Ω" is the angle range that the first rotation angle detection magnetic sensor 37 can detect, and "α" is the first driven-side rotation angle θg1. In this embodiment, "m" is 24, "z" is 48, and "Ω" is 360 degrees. "mα / z" represents the rotation angle of the main drive gear 31 relative to the first driven-side rotation angle θg1 of the first driven gear 32 within the detection range Ω of the first rotation angle detection magnetic sensor 37. The control device 110 calculates the absolute angle θpa based on expression (1).

[0049] The control device 110 acquires a first steering torque Th1 and a second steering torque Th2 calculated by the microcomputer 100. The control device 110 performs control, for example, to apply power to the motor of the steering device provided to the vehicle based on the absolute angle θpa, the first steering torque Th1 and the second steering torque Th2.

[0050] The first rotation angle detection and calculation unit 37a of the microcomputer 100 is equipped with a function to correct the first driven-side rotation angle θg1 in the angle range of 0 degrees to 360 degrees. On the other hand, the second rotation angle detection and calculation unit 38a of the microcomputer 100 is not equipped with a function to correct the second driven-side rotation angle θg2 in the angle range of 0 degrees to 360 degrees. The first driven gear 32 is used to calculate the rotation angle of the main drive gear 31, and the second driven gear 33 is used to calculate the number of rotations of the main drive gear 31.

[0051] When calculating the first driven-side rotation angle θg1, the first rotation angle detection and calculation unit 37a uses a correction angle θc to correct the first driven-side rotation angle θg1. The first rotation angle detection and calculation unit 37a stores the correction angle θc to be used to correct the first driven-side rotation angle θg1.

[0052] Figure 6 The correction angle θc stored in the first rotation angle detection calculation unit 37a is shown in solid line. The first rotation angle detection calculation unit 37a stores the correction angle θc in an angle range of 0 degrees to 360 degrees. The correction angle θc stored in the angle range of 0 degrees to 360 degrees corresponds to the first rotation angle detection magnetic sensor 37 as a relative angle sensor that detects the first driven side rotation angle θg1 of the first driven gear 32 in the angle range of 0 degrees to 360 degrees.

[0053] The first rotation angle detection and calculation unit 37a calculates the first driven-side rotation angle θg1 based on the electrical signal Sg1 before correction, and performs correction by adding the correction angle θc corresponding to the first driven-side rotation angle θg1 to the first driven-side rotation angle θg1, thereby calculating the corrected first driven-side rotation angle θg1. Figure 5 As shown, the first rotation angle detection and calculation unit 37a provides the corrected first driven side rotation angle θg1 to the control device 110.

[0054] The method for obtaining the correction angle θc will be described. Upon shipment from the factory, etc., the correction angle θc is stored in the first rotation angle detection and calculation unit 37a. To obtain the correction angle θc, firstly, the first driven gear 32 is rotated two revolutions, and the first driven-side rotation angle θg1 is obtained over its entire angular domain. The reason for rotating the first driven gear 32 two revolutions is that the number of teeth 61a of the first driven gear 32 is the number of teeth 31a of the main drive gear 31 divided by 2. Due to the relationship that the main drive gear 31 rotates one revolution for every two revolutions of the first driven gear 32, the meshing of the first driven gear 32 and the main drive gear 31 is the same during the first and third revolutions of the first driven gear 32, and also the same during the second and fourth revolutions of the first driven gear 32. The complete meshing of the first driven gear 32 with the main drive gear 31 occurs when the first driven gear 32 rotates two revolutions. Therefore, when the correction angle θc is obtained, the first driven gear 32 rotates two revolutions and obtains the first driven-side rotation angle θg1 over the entire angle domain. Note that the number "2" is the number of revolutions of the first driven gear 32 that obtains the first driven-side rotation angle θg1, and also the number of deviations used to obtain the average deviation described later. This number "2" is set to the number of revolutions corresponding to one revolution of the pinion shaft 2, which is the element with the longest period among all elements related to the rotation of the pinion shaft 2. In other words, "2" is a number obtained by dividing the number of teeth of the main drive gear 31 (which is set to rotate integrally with the input shaft of the pinion shaft 2) by the number of teeth of the first driven gear 32 (61a).

[0055] exist Figure 7 In the diagram, the first driven side rotation angle θg1, obtained through calculation when the correction angle θc is obtained, is represented by a solid line, and the actual rotation angle of the first driven gear 32 is represented by a dashed line. The actual rotation angle of the first driven gear 32 is not the designed rotation angle of the first driven gear 32, but rather the ideal angle when the actual rotation angle exhibited by the first driven gear 32 is ideally obtained. Figure 7 The diagram shows the first driven side rotation angle θg1 obtained when the first driven gear 32 rotates two revolutions, that is, rotates within the entire angular range of 0 degrees to 720 degrees, and the actual rotation angle of the first driven gear 32. For example... Figure 7 As shown, the obtained first driven side rotation angle θg1 is not completely consistent with the actual rotation angle of the first driven gear 32, and there is a difference between them.

[0056] Next, the deviation between the obtained first driven side rotation angle θg1 and the actual rotation angle of the first driven gear 32 is obtained over the entire angle domain. Figure 8The solid line shows the deviation between the obtained first driven-side rotation angle θg1 and the actual rotation angle of the first driven gear 32. This deviation can be the same in the angle range of 0 degrees to 360 degrees and in the angle range of 360 degrees to 720 degrees, but it can be different between the angle range of 0 degrees to 360 degrees and the angle range of 360 degrees to 720 degrees. Figure 8 As shown. In Figure 8 In practice, the following deviation often occurs: within the angular range of 0 to 360 degrees, the rotation angle θg1 of the first driven side before correction is greater than the actual rotation angle of the first driven gear 32, and therefore the overall deviation is usually negative. In contrast, in Figure 8 In practice, the following deviation often occurs: in the 360-720 degree angular range, compared to the 0-360 degree angular range, the rotation angle θg1 of the first driven side before correction is smaller than the actual rotation angle of the first driven gear 32, and therefore the overall deviation is usually positive. Note that factors causing this difference include electrical errors in the sensor output and mechanical errors in the gears. An example of electrical errors in the sensor output is the variance of the electrical signals Sg1 and Sg2 generated based on the input magnetic flux density. Examples of mechanical errors in the gears are breakage, wear, etc., of the teeth 31a of the main drive gear 31 and the teeth 61a of the first driven gear 32.

[0057] Next, the deviation is averaged so that the deviation over the entire angular range of 0 to 720 degrees is the same as the deviation over the angular range of 0 to 360 degrees. It is necessary to set the deviation over the angular range of 0 to 360 degrees to correspond to the first rotation angle detection magnetic sensor 37 being a relative angle sensor that detects the first driven side rotation angle θg1 of the first driven gear 32 over the angular range of 0 to 360 degrees.

[0058] Figure 6The deviations in the 0-360 degree angular range are shown by a long and a short dashed line, the deviations in the 360-720 degree angular range are shown by a long and a two short dashed line, and the average of these deviations is shown by a solid line, representing the midpoint between the deviations in the 0-360 degree angular range and the deviations in the 360-720 degree angular range. In other words, the average value is plotted as a solid line by averaging the two deviations corresponding to each identical relative rotation angle, such that the deviations in the entire 0-720 degree angular range are equal to the deviations in the 0-360 degree angular range. The average of these two deviations is obtained by dividing the sum of the deviations in the 0-360 degree angular range and the deviations in the 360-720 degree angular range for each identical relative rotation angle by 2. In this embodiment, the term "average" is used to refer to the arithmetic mean, and the average value is an arithmetic mean. As an example of the same relative rotation angle, the average value at 180 degrees is obtained using the deviation at an absolute rotation angle of 180 degrees and the deviation at an absolute rotation angle of 540 degrees. The first rotation angle detection calculation unit 37a stores the average value of the deviation obtained in this way as the correction angle θc.

[0059] The beneficial effects of this embodiment will be described. The correction angle θc stored in the first rotation angle detection and calculation unit 37a of the microcomputer 100 is an average value obtained by averaging two deviations corresponding to the same relative rotation angle. When obtaining the correction angle θc, deviations in the angle range from 0 degrees to 360 degrees are considered not only, but also deviations in the angle range exceeding 360 degrees. The first driven-side rotation angle θg1 is corrected based on the correction angle θc obtained by also considering deviations in the angle range exceeding 360 degrees, and therefore, the first driven-side rotation angle θg1 can be corrected more appropriately overall compared to correcting the first driven-side rotation angle θg1 based only on the correction angle obtained by considering deviations in the angle range from 0 degrees to 360 degrees.

[0060] For example, without considering the deviation when the rotation angle of the first driven gear 32 is 540 degrees, the correction angle when the rotation angle of the first driven gear 32 is 540 degrees is conventionally set based on the deviation when the rotation angle of the first driven gear 32 is 180 degrees. However, even if the relative rotation angle of the first driven gear 32 is the same 180 degrees at 180 degrees and at 540 degrees, the meshing positions of the main drive gear 31 and the first driven gear 32 are different, and therefore the rotation angle of the first driven gear 32 should be corrected with different correction angles respectively.

[0061] exist Figure 9In the diagram, the dashed line represents the deviation between the corrected first driven-side rotation angle θg1 and the actual rotation angle of the first driven-side gear 32 when the correction angle is obtained based only on the deviation within the angular range of 0 to 360 degrees. In this case, although the difference between the corrected first driven-side rotation angle θg1 and the actual rotation angle of the first driven-side gear 32 is small within the angular range of 0 to 360 degrees, the difference is large in the angular range exceeding 360 degrees.

[0062] In this embodiment, such as Figure 8 As shown, the first driven side rotation angle θg1 of the first driven gear 32 is corrected by considering both the deviation within 0 degrees to 360 degrees and the deviation exceeding 360 degrees. For example, in this embodiment, the correction angle θc when the rotation angle of the first driven gear 32 is 540 degrees is set as the average of the deviation when the rotation angle of the first driven gear 32 is 180 degrees and the deviation when the rotation angle of the first driven gear 32 is 540 degrees. In other words, the correction angle θc when the rotation angle of the first driven gear 32 is 540 degrees considers both the deviation when the rotation angle of the first driven gear 32 is 180 degrees and the deviation when the rotation angle of the first driven gear 32 is 540 degrees. Therefore, the following situation can be suppressed: the difference between the corrected first driven side rotation angle θg1 and the actual rotation angle of the first driven gear 32 is greater than the difference between the uncorrected first driven side rotation angle θg1 and the actual rotation angle of the first driven gear 32.

[0063] exist Figure 9 In the diagram, the solid line represents the difference between the corrected first driven side rotation angle θg1 and the actual rotation angle of the first driven gear 32 when the first driven side rotation angle θg1 is corrected based on the correction angle θc. In this case, compared to the case shown by the dashed line, the increase in the difference between the corrected first driven side rotation angle θg1 and the actual rotation angle of the first driven gear 32 in the angle range exceeding 360 degrees is suppressed. In other words, the following situation can be suppressed: when comparing the difference in the angle range from 0 degrees to 360 degrees with the difference in the angle range exceeding 360 degrees, the difference in the angle range exceeding 360 degrees is a larger difference compared to the difference in the angle range from 0 degrees to 360 degrees. Therefore, the difference between the corrected rotation angle of the first driven gear 32 and the actual rotation angle of the first driven gear 32 can be suppressed overall. Therefore, the first driven side rotation angle θg1 can be corrected more appropriately overall.

[0064] The advantages of this embodiment will be described. The first driven-side rotation angle θg1 can be corrected more appropriately, and therefore the detection accuracy of the first driven-side rotation angle θg1 can be improved.

[0065] By setting a second driven gear 33 with a different number of teeth compared to the first driven gear 32, information can be provided when obtaining the rotation angle or number of rotations of the main drive gear 31, i.e., the pinion shaft 2.

[0066] The second driven gear 33 is used to obtain the number of rotations of the first driven gear 32. Regarding the second driven gear 33, it is sufficient to obtain the rotation angle to a degree that the number of rotations of the first driven gear 21 can be distinguished, and whether the correction is performed based on the correction angle will not significantly affect the accuracy of detecting the rotation angle of the main drive gear 31. Therefore, the second rotation angle detection and calculation unit 38a of the microcomputer 100 is not given the function of correcting the detected second driven-side rotation angle θg2. Therefore, compared to correcting the second driven-side rotation angle θg2 in the same way as the first driven-side rotation angle θg1, the increase in computational load on the microcomputer 100 can be suppressed.

[0067] Biasing the first driven gear 32 and the second driven gear 33 toward the main drive gear 31 can adequately ensure meshing between the main drive gear 31 and the first driven gear 32 and the second driven gear 33. However, in the detection device 1 provided with the biasing member 36, biasing the first driven gear 32 and the second driven gear 33 toward the main drive gear 31 suppresses hysteresis at the first driven gear 32 and the second driven gear 33. Therefore, the calculation of the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2 tends to be more affected by the state of the teeth 61a of the main drive gear 31. Compared with not biasing the first driven gear 32 toward the main drive gear 31, when the first driven gear 32 is biased toward the main drive gear 31, the following states (A) and (B) tend to occur more easily. State (A) is characterized by the following: in the angular range of 0 to 360 degrees, the first driven side rotation angle θg1 before correction is greater than the actual rotation angle of the first driven gear 32; and in the angular range exceeding 360 degrees, the first driven side rotation angle θg1 before correction is less than the actual rotation angle of the first driven gear 32. State (B) is characterized by the following: in the angular range of 0 to 360 degrees, the first driven side rotation angle θg1 before correction is less than the actual rotation angle of the first driven gear 32; and in the angular range exceeding 360 degrees, the first driven side rotation angle θg1 before correction is greater than the actual rotation angle of the first driven gear 32. When these states occur, conventionally, the difference between the corrected first driven side rotation angle θg1 and the actual rotation angle of the first driven gear 32 increases in the angular range exceeding 360 degrees, as described above for the beneficial effects. Figure 9 As shown by the dashed line in the diagram, the detection device 1 with the bias member 36 has such a situation, and therefore, by using a correction angle θc that takes into account the deviation in the angular domain exceeding 360 degrees, the beneficial effect is achieved that the first driven-side rotation angle θg1 can be more properly corrected.

[0068] In addition to the first driven side rotation angle θg1, information related to the torque acting on the pinion shaft 2 can also be provided. The above embodiment can be modified as follows. Furthermore, the following other embodiments can be combined with each other without technical inconsistencies.

[0069] The microcomputer 100 can be used as a control device 110. In other words, the microcomputer 100 can receive electrical signals Sg1 and Sg2, calculate a first driven-side rotation angle θg1 and a second driven-side rotation angle θg2, and calculate an absolute angle θpa based on the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2. It is sufficient for the microcomputer 100 to have a portion that calculates the first driven-side rotation angle θg1 and also corrects for it during calculation; portions with other functions can be modified appropriately.

[0070] Although it has been described that the control device 110 obtains the number of rotations γ based on the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2, and obtains the absolute angle θpa based on the first driven-side rotation angle θg1 and the number of rotations γ according to expression (1), this is not limiting. Figure 5 As shown, the larger the absolute angle θpa, the larger the absolute value of the angle difference is proportionally to the absolute angle θpa. Therefore, for example, the control device 110 stores a mapping representing the relationship between the absolute value of the angle difference between the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2 and the absolute angle θpa. The control device 110 can calculate the angle difference between the first driven-side rotation angle θg1 and the second driven-side rotation angle θg2, and calculate the absolute angle θpa based on this angle difference.

[0071] Although this embodiment describes using an arithmetic mean to obtain the average of the deviations, this is not limiting. For example, a geometric mean can be used to obtain the average of the deviations.

[0072] Although the first rotation angle detection and calculation unit 37a of the microcomputer 100 is described in this embodiment as having the function of correcting the first driven side rotation angle θg1, the function of correcting the first driven side rotation angle θg1 can be given to another part of the microcomputer 100.

[0073] Although the first rotation angle detection and calculation unit 37a of the microcomputer 100 is described in this embodiment as storing the correction angle θc, the correction angle θc may be stored in another part of the microcomputer 100.

[0074] Although the microcomputer 100 is described in this embodiment as not being given the function of correcting the detected second driven side rotation angle θg2, this function can be given to the microcomputer 100. The number of teeth of the main drive gear 31, the first driven gear 32, and the second driven gear 33 can be appropriately changed.

[0075] Although this embodiment describes the number of teeth 61a of the first driven gear 32 as obtained by dividing the number of teeth 31a of the main drive gear 31 by 2, this is not limiting. The number of teeth 61a of the first driven gear 32 can also be obtained by dividing the number of teeth 31a of the main drive gear 31 by 3 or a larger integer.

[0076] The rotation angle sensor 30 can be configured with a single driven gear, or it can be configured with three or more driven gears. In other words, it is sufficient to provide the rotation angle sensor 30 with one or more driven gears, the number of teeth of which is obtained by dividing the number of teeth 31a of the main drive gear 31 by an integer.

[0077] Although this embodiment describes the use of a torsion coil spring as the biasing member 36 for biasing the first driven gear 32 and the second driven gear 33 toward the main drive gear 31, this is not limiting. Leaf springs or other coil springs may be used as biasing members. For example, the biasing member for biasing the first driven gear 32 toward the main drive gear 31 and the biasing member for biasing the second driven gear 33 toward the main drive gear 31 may be constructed as independent biasing members.

[0078] Although this embodiment describes the provision of a biasing member 36 that biases the first driven gear 32 and the second driven gear 33 toward the main drive gear 31, an arrangement without the biasing member 36 may be used. In this case, for example, the following arrangement is sufficient: the first driven gear 32 and the second driven gear 33 are rotatably supported relative to the first support hole 50 and the second support hole 51 provided in the support member 34.

[0079] In this embodiment, the detection device 1 can be a rotation angle sensor 30 that omits the torque sensor 20. The rotation angle sensor 30 also serves the same purpose as the detection device 1.

[0080] Although an example of a vehicle's steering mechanism has been given in this embodiment as the mounting location for the detection device 1, it can be applied to other vehicle-mounted devices with a rotating shaft. Furthermore, the detection device 1 is not limited to vehicle-mounted use.

Claims

1. A rotation angle detecting device (1) characterized by include: The correction target driven gear (32) is a driven gear that meshes with the main drive gear (31), which is mounted on the rotating shaft (2) so as to be able to rotate integrally with the rotating shaft (2); A first sensor (37) is configured to generate an electrical signal based on the rotation of the driven gear (32) of the calibration object; An electronic control unit (100) is configured to calculate a driven-side rotation angle based on an electrical signal generated by the first sensor (37), the driven-side rotation angle being the rotation angle of the driven gear (32) of the calibration object; The uncorrected driven gear (33) meshes with the main drive gear (31) and is a different driven gear from the corrected driven gear (32); as well as The second sensor (38) is configured to generate an electrical signal based on the rotation of the calibration-free driven gear (33), wherein The number of teeth of the driven gear (32) of the correction object is obtained by dividing the number of teeth of the main drive gear (31) by an integer. The number of teeth of the driven gear (32) to be calibrated and the number of teeth of the driven gear (33) to be exempted from calibration are different from each other. The electronic control unit (100) is configured to store a correction angle, which is used to correct the driven-side rotation angle when calculating the driven-side rotation angle. The correction angle is a predetermined deviation within a predetermined angle range. The correction angle is an average value obtained by averaging deviations equal to the integer value and corresponding to the same relative rotation angle, thus serving as the deviation within the angle range of 0 to 360 degrees. The predetermined deviation is the deviation obtained within the predetermined angle range and is the deviation between the driven-side rotation angle and the actual rotation angle of the driven gear (32) being corrected. The driven-side rotation angle is obtained over the entire angle range when the driven gear (32) being corrected has rotated a number of revolutions equal to the integer value. The electronic control unit (100) is configured to calculate the rotation angle of the uncorrected driven gear (33) based on the electrical signal generated by the second sensor (38), and is configured not to perform correction of the rotation angle of the uncorrected driven gear (33) based on the correction angle. The electronic control unit (100) calculates the number of rotations of the driven gear (32) to be corrected based on the angle difference between the rotation angle of the driven side and the rotation angle of the uncorrected driven gear (33).

2. The rotation angle detecting device (1) according to claim 1, characterized in that Also includes: A biasing member configured to bias the corrected object driven gear (32) toward the main drive gear (31).

3. The rotation angle detection device (1) according to claim 1, characterized in that... Also includes: A biasing member configured to bias the calibrated driven gear (32) and the uncalibrated driven gear (33) toward the main drive gear (31).

4. The rotation angle detecting device (1) according to any one of claims 1 to 3, characterized in that Also includes: a torque sensor (20) configured to detect a torque acting on the rotation shaft (2).

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